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1
Breitkreuz, Sarah, Laio Silva Sobrinho, Leah Stachniak, and Scott Chang. "Can the Adaptive Multi-Paddock Grazing System Increase Carbon Sequestration in Alberta's Grassland Soils?" Alberta Academic Review 2, no. 2 (September 11, 2019): 13–14. http://dx.doi.org/10.29173/aar52.
Full textAbstract:
Natural grasslands cover around 40% of the Earth’s surface and play an important role as a source of ecological goods and services. By sequestering around 30% of terrestrial global carbon, grasslands play a critical part in the alleviation of climate change. Despite their ecological significance, grasslands have been reduced to a fraction of their original extent. In Canada, up to 70% of grasslands have been destroyed, making it the most endangered ecosystem in North America. What remains is often intensely grazed and a diverse ecosystem of wild animals is replaced by domestic livestock. The continuous application of poor grazing management by ranchers is one of the main causes for the depletion of natural grasslands, resulting in the release of stored soil carbon back into the atmosphere. Fortunately, 60-70% of the depleted carbon can be re-sequestered through the adoption of improved grazing management, thus improving grassland ecosystems. The Adaptive Multi-Paddock (AMP) grazing system is an example of improved grazing management. AMP grazing is a system in which livestock is frequently rotated between multiple fenced paddocks. Compared to conventional grazing practices (Non-AMP), the AMP system is a favorable solution which can improve carbon sequestration in world wide grasslands soils– and in turn, contribute to the mitigation of climate change. By regenerating grassland ecosystems, AMP grazing could potentially aid in creating a more sustainable, resilient agroecosystem. Our goal is to study the effect of AMP grazing on soil organic carbon (SOC) sequestration in Canadian grasslands. First, we collected soil cores from 30 study sites located throughout the grassland ecoregions in Canada. Each site consisted of a pair of ranches: one AMP and one Non-AMP. Second, we analyzed the soil cores for total carbon using an elemental analyzer. There does not seem to be any substantial difference in total carbon between AMP and Non-AMP systems, however we have yet to differentiate between soil organic carbon and soil inorganic carbon. Once we distinguish the two variables we will be able to confirm the effectiveness of the AMP grazing system in increasing carbon sequestration in Canadian grasslands.
Literature Cited:
Derner, J. D., & Schuman, G. E. (2007). Carbon sequestration and rangelands: a synthesis of land management and precipitation effects. Journal of soil and water conservation, 62(2), 77-85.
Gauthier, D. A., & Wiken, E. B. (2003). Monitoring the conservation of grassland habitats, Prairie Ecozone, Canada. Environmental Monitoring and Assessment, 88(1-3), 343-364.
Samson, F., & Knopf, F. (1994). Roundtable: prairie conservation in North America. BioScience, 44(6), 418-421
Kraus, D. (2016). Why Canada’s Prairies are the World’s Most Endangered Ecosystem. Retrieved from: http://www.natureconservancy.ca/en/blog/archive/grasslands-the-most.html#.XUnsE-hKi70
Lal, R. (2002). Soil carbon dynamics in cropland and rangeland. Environmental pollution, 116(3), 353-362
Teague, W. R. (2018). Forages and pastures symposium: Cover crops in livestock production: Whole-system approach: Managing grazing to restore soil health and farm livelihoods. Journal of animal science, 96(4), 1519-1530.
2
Chang, J. F., N. Viovy, N. Vuichard, P. Ciais, T. Wang, A. Cozic, R. Lardy, et al. "Incorporating grassland management in ORCHIDEE: model description and evaluation at 11 eddy-covariance sites in Europe." Geoscientific Model Development 6, no. 6 (December 20, 2013): 2165–81. http://dx.doi.org/10.5194/gmd-6-2165-2013.
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Abstract. This study describes how management of grasslands is included in the Organizing Carbon and Hydrology in Dynamic Ecosystems (ORCHIDEE) process-based ecosystem model designed for large-scale applications, and how management affects modeled grassland–atmosphere CO2 fluxes. The new model, ORCHIDEE-GM (grassland management) is enabled with a management module inspired from a grassland model (PaSim, version 5.0), with two grassland management practices being considered, cutting and grazing. The evaluation of the results from ORCHIDEE compared with those of ORCHIDEE-GM at 11 European sites, equipped with eddy covariance and biometric measurements, shows that ORCHIDEE-GM can realistically capture the cut-induced seasonal variation in biometric variables (LAI: leaf area index; AGB: aboveground biomass) and in CO2 fluxes (GPP: gross primary productivity; TER: total ecosystem respiration; and NEE: net ecosystem exchange). However, improvements at grazing sites are only marginal in ORCHIDEE-GM due to the difficulty in accounting for continuous grazing disturbance and its induced complex animal–vegetation interactions. Both NEE and GPP on monthly to annual timescales can be better simulated in ORCHIDEE-GM than in ORCHIDEE without management. For annual CO2 fluxes, the NEE bias and RMSE (root mean square error) in ORCHIDEE-GM are reduced by 53% and 20%, respectively, compared to ORCHIDEE. ORCHIDEE-GM is capable of modeling the net carbon balance (NBP) of managed temperate grasslands (37 ± 30 gC m−2 yr−1 (P < 0.01) over the 11 sites) because the management module contains provisions to simulate the carbon fluxes of forage yield, herbage consumption, animal respiration and methane emissions.
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Bi, Xu, Bo Li, Xiangchao Xu, and Lixin Zhang. "Response of Vegetation and Soil Characteristics to Grazing Disturbance in Mountain Meadows and Temperate Typical Steppe in the Arid Regions of Central Asian, Xinjiang." International Journal of Environmental Research and Public Health 17, no. 12 (June 25, 2020): 4572. http://dx.doi.org/10.3390/ijerph17124572.
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Grazing is one of the most common causes of grassland degradation, therefore, an assessment of soil physicochemical properties and plant nutrients under grazing is important for understanding its influences on ecosystem nutrient cycling and for formulating appropriate management strategies. However, the effects of grazing on grassland soil physicochemical properties and plant nutrients in mountain meadow and temperate typical steppe in the arid regions are still unclear. Therefore, we investigated the vegetation nutrient concentrations of nitrogen, phosphorus and potassium (N, P, and K) as well as soil physicochemical properties in the topmost 40 cm depth soil, to evaluate how these factors respond to grazing disturbance in a mountain meadow and temperate typical steppe within a mountain basin system in arid regions. Our results revealed that the soil bulk density values at depth of 0–40 cm increased after grazing in the mountain meadow and temperate typical steppe, whereas the soil water content decreased in the mountain meadow and increased in the temperate typical steppe after grazing. In the mountain meadow, soil total N and available P in addition to vegetation N and P concentrations increased in response to high-intensity grazing, while soil available N, available K and vegetation K decreased after grazing; in addition, soil pH, soil total P and K showed no significant changes. In the temperate typical steppe, the soil total P, soil available N, P, and K, and vegetation N, P, and K increased under relatively low-intensity grazing, whereas soil pH and soil total K showed no significant changes except for the deceasing soil total N. Our findings showed the different responses of different grassland ecosystems to grazing. Moreover, we propose that further related studies are necessary to better understand the effects of grazing on grassland ecosystems, and thereby provide a theoretical basis for the sustainable use of animal husbandry and ecological restoration of grasslands.
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Gong, Y. M., A. Mohammat, X. J. Liu, K. H. Li, P. Christie, F. Fang, W. Song, et al. "Response of carbon dioxide emissions to sheep grazing and N application in an alpine grassland – Part 2: Effect of N application." Biogeosciences 11, no. 7 (April 3, 2014): 1751–57. http://dx.doi.org/10.5194/bg-11-1751-2014.
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Abstract. Widespread nitrogen (N) enrichment resulting from anthropogenic activities has led to great changes in carbon exchange between the terrestrial biosphere and the atmosphere. Grassland is one of the most sensitive ecosystems to N deposition. However, the effect of N deposition on ecosystem respiration (Re) in grasslands has been conducted mainly in temperate grasslands, which are limited largely by water availability, with few studies focused on alpine grasslands that are primarily constrained by low temperatures. Failure to assess the magnitude of the response in Re outside the growing season (NGS) in previous studies also limits our understanding of carbon exchange under N deposition conditions. To address these knowledge gaps we used a combination of static closed chambers and gas chromatography in an alpine grassland from 2010 to 2011 to test the effects of N application on ecosystem respiration (Re) both inside and outside the growing season. There was no significant change in CO2 emissions under N application. Re outside the growing season was at least equivalent to 9.4% of the CO2 fluxes during the growing season (GS). Annual Re was calculated to be 279.0–403.9 g CO2 m−2 yr−1 in Bayinbuluk alpine grasslands. In addition, our results indicate that soil temperature was the dominant abiotic factor regulating variation in Re in the cold and arid environment. Our results suggest that short-term N additions exert no significant effect on CO2 emissions in alpine grassland.
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Huang, Xiaotao, Li Ma, Geping Luo, Chunbo Chen, Gangyong Li, Yang Yan, Huakun Zhou, Buqing Yao, and Zhen Ma. "Human appropriation of net primary production estimates in the Xinjiang grasslands." PLOS ONE 15, no. 12 (December 2, 2020): e0242478. http://dx.doi.org/10.1371/journal.pone.0242478.
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The human appropriation of net primary production (HANPP) was developed to estimate the intensity of human activities in natural ecosystems, which is still unclear in the Xinjiang grasslands. Using the Biome-Biogeochemical Cycle (Biome-BGC) grazing model in combination with field data, we assessed the HANPP and explored its spatiotemporal patterns in the Xinjiang grasslands. Our results showed that (1) the HANPP increased from 38 g C/m2/yr in 1979 to 88 g C/m2/yr in 2012, with an average annual increase of 1.47%. The HANPP was 80 g C/m2/yr, which represented 51% of the potential net primary production (NPPpot), and the HANPP efficiency was 70% in this region. (2) The areas with high HANPP values mainly occurred in northern Xinjiang and northwest of the Tianshan Mountains, while areas with low HANPP values mainly occurred in southern Xinjiang and southwest of the Tianshan Mountains. (3) Interannual variations in HANPP and NPPpot were significantly positively correlated (P<0.01). Interannual variations in HANPP efficiency and grazing intensity were negatively correlated (P<0.01). These results can help identify the complex impacts of human activities on grassland ecosystems and provide basic data for grassland management.
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Gong, Y. M., A. Mohammat, X. J. Liu, K. H. Li, P. Christie, F. Fang, W. Song, et al. "Response of carbon dioxide emissions to sheep grazing and N application in an alpine grassland – Part 1: Effect of sheep grazing." Biogeosciences 11, no. 7 (April 3, 2014): 1743–50. http://dx.doi.org/10.5194/bg-11-1743-2014.
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Abstract. Previous work has failed to address fully the response of (autotrophic and heterotrophic) respiration to grazing in different ecosystems, particularly in alpine grasslands outside the growing season. From 2010 to 2011 a field experiment combined two methods (static closed chambers and a closed dynamic soil CO2 flux system) in alpine grasslands located in the Tianshan Mountains. We examined the effects of grazing regime on ecosystem respiration (Re) both outside (NGS) and during (GS) the growing season and determined the pattern of Re in relation to climate change. There was no significant change in CO2 emissions under grazing. Heterotrophic respiration (Rh) accounted for 78.5% of Re with short-term grazing exclusion and 93.2% of Re with long-term grazing exclusion. Re, Rh and autotrophic respiration (Ra) fluxes outside the growing season were equivalent to 12.9%, 14.1% and 11.4% of the respective CO2 fluxes during the growing season. In addition, our results indicate that soil water content played a critical role in Ra in the cold and arid environment. Both Rh and Re were sensitive to soil temperature. Moreover, our results suggest that grazing exerted no significant effect on CO2 emissions in these alpine grasslands.
7
Zhai, Xiajie, Tingting Lu, Shiming Tang, Xiaojuan Liu, Xiuzhi Ma, Guodong Han, Andreas Wilkes, and Chengjie Wang. "Methane Emission from Sheep Respiration and Sheepfolds During the Grazing Season in a Desert Grassland." Open Atmospheric Science Journal 9, no. 1 (December 22, 2015): 23–28. http://dx.doi.org/10.2174/1874282301509010023.
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Methane (CH4) emissions from ruminants should be accounted for the natural grazed rangeland ecosystems when devising greenhouse gas budget inventory, in particular, their contribution to global warming. In this study, CH4 emission from sheep respiration at different grazing intensities (light grazing, 0.75 sheep/ha, LG; moderate grazing, 1.50 sheep/ha, MG; and heavy grazing, 2.25 sheep/ha, HG) and in sheepfolds were evaluated in a desert grassland of Inner Mongolia. Results indicated that daily CH4 emission from sheep was not significantly different between treatments. When CH4 emission was expressed emission per 100g daily, there was a significant difference of LG vs HG and MG vs HG, with the values of 15.64g, 20.00g and 28.63g for LG, MG and HG, respectively, during the grazing season. There was no significant difference among CH4 fluxes in sheepfolds (mean 39.0 ug m-1 h-1). Considering CH4 emissions from the grazing ecosystem, net CH4 emissions from LG, MG and HG plots were -18.33, -1.91 and 21.19 g/ha/day, respectively. The digestibility of forage had a positive correlation with CH emission expressed on daily and metabolic body weight basis. It is concluded that MG will improve the balance between CH emission from grassland and grazing livestock in the desert grasslands of Inner Mongolia.
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Soubry, Irini, Thuy Doan, Thuan Chu, and Xulin Guo. "A Systematic Review on the Integration of Remote Sensing and GIS to Forest and Grassland Ecosystem Health Attributes, Indicators, and Measures." Remote Sensing 13, no. 16 (August 18, 2021): 3262. http://dx.doi.org/10.3390/rs13163262.
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It is important to protect forest and grassland ecosystems because they are ecologically rich and provide numerous ecosystem services. Upscaling monitoring from local to global scale is imperative in reaching this goal. The SDG Agenda does not include indicators that directly quantify ecosystem health. Remote sensing and Geographic Information Systems (GIS) can bridge the gap for large-scale ecosystem health assessment. We systematically reviewed field-based and remote-based measures of ecosystem health for forests and grasslands, identified the most important ones and provided an overview on remote sensing and GIS-based measures. We included 163 English language studies within terrestrial non-tropical biomes and used a pre-defined classification system to extract ecological stressors and attributes, collected corresponding indicators, measures, and proxy values. We found that the main ecological attributes of each ecosystem contribute differently in the literature, and that almost half of the examined studies used remote sensing to estimate indicators. The major stressor for forests was “climate change”, followed by “insect infestation”; for grasslands it was “grazing”, followed by “climate change”. “Biotic interactions, composition, and structure” was the most important ecological attribute for both ecosystems. “Fire disturbance” was the second most important for forests, while for grasslands it was “soil chemistry and structure”. Less than a fifth of studies used vegetation indices; NDVI was the most common. There are monitoring inconsistencies from the broad range of indicators and measures. Therefore, we recommend a standardized field, GIS, and remote sensing-based approach to monitor ecosystem health and integrity and facilitate land managers and policy-makers.
9
Gong, Y. M., A. Mohammat, X. J. Liu, K. H. Li, P. Christie, F. Fang, W. Song, et al. "Response of carbon dioxide emissions to sheep grazing and nitrogen application in an alpine grassland." Biogeosciences Discussions 10, no. 7 (July 22, 2013): 12285–311. http://dx.doi.org/10.5194/bgd-10-12285-2013.
Full textAbstract:
Abstract. Previous work has failed to address fully the response of (autotrophic and heterotrophic) respiration to grazing and nitrogen (N) addition in different ecosystems, particularly in alpine grasslands outside the growing season. From 2010 to 2011, we combined two methods (static closed chambers and a closed dynamic soil CO2 flux system) in a controlled field experiment in an alpine grassland in the Tianshan Mountains. We examined the effects of grazing and N application on ecosystem respiration (Re) both outside (NGS) and during (GS) the growing season and determined the pattern of Re in relation to climate change. There was no significant change in CO2 emissions under grazing or N application. Heterotrophic respiration (Rh) accounted for 78.5% of Re. Re, Rh and autotrophic respiration (Ra) outside the growing season were equivalent to 12.9, 14.1 and 11.4% of the respective CO2 fluxes during the growing season. In addition, our results indicate that precipitation (soil water content) plays a critical role in Ra in this cold and arid environment. Both Rh and Re were sensitive to soil temperature. Moreover, our results suggest that grazing and N addition exert no significant effect on CO2 emissions in alpine grassland but may alter soil carbon stocks in alpine grassland.
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Yan, Dongqing, Jing Ren, Jiamei Liu, Yu Ding, and Jianming Niu. "De novo assembly, annotation, marker discovery, and genetic diversity of the Stipa breviflora Griseb. (Poaceae) response to grazing." PLOS ONE 15, no. 12 (December 22, 2020): e0244222. http://dx.doi.org/10.1371/journal.pone.0244222.
Full textAbstract:
Grassland is one of the most widely-distributed ecosystems on Earth and provides a variety of ecosystem services. Grasslands, however, currently suffer from severe degradation induced by human activities, overgrazing pressure and climate change. In the present study, we explored the transcriptome response of Stipa breviflora, a dominant species in the desert steppe, to grazing through transcriptome sequencing, the development of simple sequence repeat (SSR) markers, and analysis of genetic diversity. De novo assembly produced 111,018 unigenes, of which 88,164 (79.41%) unigenes were annotated. A total of 686 unigenes showed significantly different expression under grazing, including 304 and 382 that were upregulated and downregulated, respectively. These differentially expressed genes (DEGs) were significantly enriched in the “alpha-linolenic acid metabolism” and “plant-pathogen interaction” pathways. Based on transcriptome sequencing data, we developed eight SSR molecular markers and investigated the genetic diversity of S. breviflora in grazed and ungrazed sites. We found that a relatively high level of S. breviflora genetic diversity occurred under grazing. The findings of genes that improve resistance to grazing are helpful for the restoration, conservation, and management of desert steppe.
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Fayiah, Moses, ShiKui Dong, Sphiwe Wezzie Khomera, Syed Aziz Ur Rehman, Mingyue Yang, and Jiannan Xiao. "Status and Challenges of Qinghai–Tibet Plateau’s Grasslands: An Analysis of Causes, Mitigation Measures, and Way Forward." Sustainability 12, no. 3 (February 4, 2020): 1099. http://dx.doi.org/10.3390/su12031099.
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Grassland ecosystems on the Qinghai–Tibet Plateau (QTP) provide numerous ecosystem services and functions to both local communities and the populations living downstream through the provision of water, habitat, food, herbal medicines, and shelter. This review examined the current ecological status, degradation causes, and impacts of the various grassland degradation mitigation measures employed and their effects on grassland health and growth in the QTP. Our findings revealed that QTP grasslands are continually being degraded as a result of complex biotic and abiotic drivers and processes. The biotic and abiotic actions have resulted in soil erosion, plant biomass loss, soil organic carbon loss, a reduction in grazing and carrying capacity, the emergence of pioneer plant species, loss of soil nutrients, and an increase in soil pH. A combination of factors such as overgrazing, land-use changes, invasive species encroachment, mining activities, rodent burrowing activities, road and dam constructions, tourism, migration, urbanization, and climate change have caused the degradation of grasslands on the QTP. A conceptual framework on the way forward in tackling grassland degradation on the QTP is presented together with other appropriate measures needed to amicably combat grassland degradation on the QTP. It is recommended that a comprehensive and detailed survey be carried out across the QTP to determine the percentage of degraded grasslands and hence, support a sound policy intervention.
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Wang, Ling, Manuel Delgado-Baquerizo, Deli Wang, Forest Isbell, Jun Liu, Chao Feng, Jushan Liu, et al. "Diversifying livestock promotes multidiversity and multifunctionality in managed grasslands." Proceedings of the National Academy of Sciences 116, no. 13 (March 8, 2019): 6187–92. http://dx.doi.org/10.1073/pnas.1807354116.
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Increasing plant diversity can increase ecosystem functioning, stability, and services in both natural and managed grasslands, but the effects of herbivore diversity, and especially of livestock diversity, remain underexplored. Given that managed grazing is the most extensive land use worldwide, and that land managers can readily change livestock diversity, we experimentally tested how livestock diversification (sheep, cattle, or both) influenced multidiversity (the diversity of plants, insects, soil microbes, and nematodes) and ecosystem multifunctionality (including plant biomass production, plant leaf N and P, above-ground insect abundance, nutrient cycling, soil C stocks, water regulation, and plant–microbe symbiosis) in the world’s largest remaining grassland. We also considered the potential dependence of ecosystem multifunctionality on multidiversity. We found that livestock diversification substantially increased ecosystem multifunctionality by increasing multidiversity. The link between multidiversity and ecosystem multifunctionality was always stronger than the link between single diversity components and functions. Our work provides insights into the importance of multitrophic diversity to maintain multifunctionality in managed ecosystems and suggests that diversifying livestock could promote both multidiversity and ecosystem multifunctionality in an increasingly managed world.
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Evans, Edward W., Lisa M. Ellsworth, and Creighton M. Litton. "Impact of grazing on fine fuels and potential wildfire behaviour in a non-native tropical grassland." Pacific Conservation Biology 21, no. 2 (2015): 126. http://dx.doi.org/10.1071/pc14910.
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Non-native grass invasion has increased fuel loads and fire frequency in areas throughout the tropics, resulting in a non-native grass–wildfire cycle with negative impacts on native biodiversity and ecological processes. Megathyrsus maximus (guinea grass) invades dry and mesic ecosystems throughout the tropics, increasing fuel loads and wildfire intensity. Eradication of M. maximus is difficult, making effective wildfire management critical to the protection of adjacent developed areas and remnant native ecosystems. The use of domestic livestock grazing in non-native grass ecosystems may be effective at decreasing fine fuel loads and potential wildfire behaviour. Our objectives were to: (1) quantify live and dead fine fuel loads and moistures in a M. maximus–dominated ecosystem before and after cattle grazing, and (2) use these data to model potential wildfire behaviour in grazed and ungrazed M. maximus grasslands with the BehavePlus fire modelling system. Fine fuel loads and moistures, climate variables, and predicted wildfire behaviour were quantified at the same site (n = 1) over two 5-month periods (March–July 2009, ungrazed; March–July 2010, grazed) in the Wai‘anae Kai Forest Reserve on the Island of O‘ahu, Hawai‘i. Strong to conclusive evidence existed that cattle grazing in this system decreased dead and total fuel loads, but did not alter live fuel loads, or live and dead fuel moistures. Modelled wildfire behaviour under both low and average fuel moisture scenarios revealed that grazing decreased the potential rate of spread by 44–52% and flame length by 36–41%. These results demonstrate that cattle grazing may be an effective approach for reducing fuel loads and potential wildfire behaviour in non-native-dominated grasslands on tropical islands.
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Gracheva, Raisa, Elena Belonovskaya, and Vera Vinogradova. "Mountain grassland ecosystems on abandoned agricultural terraces (Russia, North Caucasus)." Hacquetia 17, no. 1 (June 1, 2018): 61–71. http://dx.doi.org/10.1515/hacq-2017-0010.
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Abstract Terraces represent one of the most common agricultural landscape elements in the mountainous regions of the North Caucasus. In the Central and West Caucasus, most of the arable terraces were converted into grasslands for grazing and haymaking 60-70 years ago and then abandoned or underused during the last 20-25 years. The role of abandoned terraces in maintaining the diversity of grasslands of the mountain slopes was studied in the case of eight terraces of different types. Plant communities of subalpine meadows and meadow steppes were distinguished on the terraces depending mainly on slope steepness at the same altitudes and to a lesser extent on the slope aspect. In general, the grasslands of the terrace platforms and those of original unterraced slopes had similar traits. At that, the mesophilous communities on the rich soils of terrace edges and scarp communities similar to vegetation of steep slopes with eroded soils create regular patterns on the terraced slopes. Thus, former agricultural terraces conditioning geodiversity also contribute to the diversity of plant communities and landscape fragmentation. The current increase of temperature and humidity may lead to a reduction of climatic differences of the slopes, and the further convergence of grassland communities can be assumed.
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Guo, Zheng Gang, Tian Gang Liang, Xing Yuan Liu, and Fu Jun Niu. "A new approach to grassland management for the arid Aletai region in Northern China." Rangeland Journal 28, no. 2 (2006): 97. http://dx.doi.org/10.1071/rj05018.
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Land degradation in the arid Aletai Region in northern China is not only detrimental to animal production, but also reduces the ability to conserve water resources by destabilising the catchments of rivers which affects runoff, thus, threatening the sustainable use of these grasslands. A new approach to grassland management based on carrying capacity and ecological services value of grassland types, using an index of classification management (ICG), was designed to ensure the sustainability of grassland ecosystems. In this approach, grassland is classified into 3 management sectors. The first is conservation grassland, which is mainly devoted to ecological and social values; the second is the moderately productive grassland, dedicated to multiple benefits by rational use; and the third is intensively productive grassland, focusing on maximum economic effect. For the arid Aletai region, no intensively productive grassland was available. Conservation grassland occupied 2.5 million ha, accounted for 25.4% of grassland area, and included alpine meadow, mountain meadow, mountain meadow steppe, mountain steppe and flat meadow. In these grasslands, grazing should be eliminated to allow restoration of degenerated areas, protect grasslands with important ecological values from destruction, and to further improve the environment. Moderately productive grassland covered 7.3 million ha, and the grassland types were alpine steppe, mountain desert steppe, plain desert steppe, steppe desert, and plain desert. Agricultural measures, such as fertiliser and irrigation application, should be used to enhance the productivity of these grasslands.
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Carter, John, Allison Jones, Mary O’Brien, Jonathan Ratner, and George Wuerthner. "Holistic Management: Misinformation on the Science of Grazed Ecosystems." International Journal of Biodiversity 2014 (April 23, 2014): 1–10. http://dx.doi.org/10.1155/2014/163431.
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Over 3 billion hectares of lands worldwide are grazed by livestock, with a majority suffering degradation in ecological condition. Losses in plant productivity, biodiversity of plant and animal communities, and carbon storage are occurring as a result of livestock grazing. Holistic management (HM) has been proposed as a means of restoring degraded deserts and grasslands and reversing climate change. The fundamental approach of this system is based on frequently rotating livestock herds to mimic native ungulates reacting to predators in order to break up biological soil crusts and trample plants and soils to promote restoration. This review could find no peer-reviewed studies that show that this management approach is superior to conventional grazing systems in outcomes. Any claims of success due to HM are likely due to the management aspects of goal setting, monitoring, and adapting to meet goals, not the ecological principles embodied in HM. Ecologically, the application of HM principles of trampling and intensive foraging are as detrimental to plants, soils, water storage, and plant productivity as are conventional grazing systems. Contrary to claims made that HM will reverse climate change, the scientific evidence is that global greenhouse gas emissions are vastly larger than the capacity of worldwide grasslands and deserts to store the carbon emitted each year.
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Chanasyk, David S., and M. Anne Naeth. "Grazing impacts on bulk density and soil strength in the foothills fescue grasslands of Alberta, Canada." Canadian Journal of Soil Science 75, no. 4 (November 1, 1995): 551–57. http://dx.doi.org/10.4141/cjss95-078.
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Alberta foothills fescue grasslands are very productive ecosystems but there is concern that the traditional season-long (continuous) grazing regimes may be leading to soil deterioration due to compaction and increased soil strength. The objectives of this study were to quantify grazing effects on soil bulk density and soil strength of sloped areas in the Alberta foothills fescue grasslands at the Agriculture Canada Stavely Range Substation. The effects of two grazing intensities (heavy and very heavy) for two treatments (short duration and continuous) on these two parameters were compared to an ungrazed control. Soil bulk density and soil water to a depth of 7.5 cm were measured with a surface water/density gauge. Soil strength was measured with a hand-pushed cone penetrometer to a depth of 45 cm. Cone index, the maximum penetration resistance in a given depth interval, was used as a measurement parameter for soil strength.Grazing affected both soil bulk density and penetration resistance. Even short-duration treatments affected these soil properties, although their effects were similar for both heavy and very heavy grazing intensities. Distinction between heavy and very heavy continuous grazing treatments was clear for both bulk density and penetration resistance, with the very heavy treatment having the greatest detrimental effect on these two soil parameters for all treatments. Bulk density and soil strength values were always lowest in the spring after snowmelt and highest late in the growing season, reflecting the water status of these ecosystems. Identical treatment rankings were obtained using bulk density and penetration resistance, but cone index was a more sensitive indicator of the effects of grazing than bulk density. Key words: Grazing, fescue grasslands, bulk density, soil strength
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Guangyu, Zhu, Tang Zhuangsheng, Chen Lei, Shangguan Zhouping, and Deng Lei. "Overgrazing depresses soil carbon stock through changing plant diversity in temperate grassland of the Loess Plateau." Plant, Soil and Environment 64, No. 1 (January 16, 2018): 1–6. http://dx.doi.org/10.17221/610/2017-pse.
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This study mainly estimates the effect of grazing on plant diversity and soil storages on the northern Loess Plateau of China. Four grazing intensities of ungrazed (UG), light (LG), moderate (MG), and heavy (HG) grassland were selected according to the vegetation utilization across the study area, in which plant diversity, heights, above- and belowground biomass, and soil carbon (C) stock were investigated. The results showed that overgrazing negatively affected plant growth and soil C stock. Plant cover, height, litter, above- and belowground productivity, as well as soil C stock significantly decreased with the increasing grazing intensity. Meanwhile, the UG and LG had higher grasses biomass together with lower forbs (P < 0.01) compared with MG and HG. The abundance of dominating grasses species, such as Stipa bungeana and S. grandis were decreased through long-term grazing as grasses species are palatable for herbivores, and the dominating forbs species, such as Artemisia capillaries and Thymus mongolicus were significantly increased with increasing grazing intensities. The results indicated that grazing exclusion or light grazing had positive effects on the sustainable development of grassland ecosystems. Therefore, a balanced use and a long-term efficient management of grasslands were better measures to counteract their local degradations.
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Ahmed, Ahmed Ibrahim, Lulu Hou, Ruirui Yan, Xiaoping Xin, and Yousif Mohamed Zainelabdeen. "The Joint Effect of Grazing Intensity and Soil Factors on Aboveground Net Primary Production in Hulunber Grasslands Meadow Steppe." Agriculture 10, no. 7 (July 3, 2020): 263. http://dx.doi.org/10.3390/agriculture10070263.
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The management practices required for grazing management will continue to increase, as necessitated by the reported rate of reduction in productivity, coupled with the degradation of Inner Mongolian steppe ecosystems. The current study was conducted to (i) examine the responses of aboveground net primary production (ANPP) to different grazing intensities and its relationship with soil factors and (ii) study the effects of grazing intensity on herbage growth and dry matter intake in Hulunber grasslands, Northeastern China. Six grazing rate treatments (G0.00, G0.23, G0.34, G0.46, G0.69, and G0.92 animal unit (AU ha−1) for zero, two, three, four, six, and eight young cows with ranging weight of 250–300 kg/plot), with three replications, were established during two consecutive growing seasons in 2017 and 2018. Our study concentrated on the grazing-induced degradation processes by different intensities of grazing. The highest decrease in aboveground biomass (AGB) was 64.1% and 59.3%, in 2017 and 2018, respectively, by the G0.92 treatment as compared with the G0.00 treatment. There was a positive relationship between yearly precipitation and ANPP. The grazing tolerance and growth rate of forage were higher in the wet year than in the dry year. Understanding the ecological consequences of grazing intensity provides useful information for assessing current grazing management scenarios and taking timely adaptation measures to maintain grassland capacity in a short and long-term system.
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Cao, Juan, Ruirui Yan, Xiaoyong Chen, Xu Wang, Qiang Yu, Yunlong Zhang, Chen Ning, Lulu Hou, Yongjuan Zhang, and Xiaoping Xin. "Grazing Affects the Ecological Stoichiometry of the Plant–Soil–Microbe System on the Hulunber Steppe, China." Sustainability 11, no. 19 (September 24, 2019): 5226. http://dx.doi.org/10.3390/su11195226.
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Grazing affects nutrient cycling processes in grasslands, but little is known by researchers about effects on the nutrient stoichiometry of plant–soil–microbe systems. In this study, the influence of grazing intensity (0, 0.23, 0.34, 0.46, 0.69, and 0.92 AU ha−1) on carbon (C), nitrogen (N) and phosphorus (P) and their stoichiometric ratios in plants, soil, and microbes was investigated in a Hulunber meadow steppe, Northeastern China. The C:N and C:P ratios of shoots decreased with grazing increased. Leaf N:P ratios <10 suggested that the plant communities under grazing were N-limited. Heavy grazing intensities increased the C:N and C:P ratios of microbial biomass, but grazing intensity had no significant effects on the stoichiometry of soil nutrients. The coupling relationship of C:N ratio in plant–soil–microbial systems was tightly significant compared to C:P ratio and N:P ratio according to the correlation results. The finding suggested grazing exacerbated the competition between plants and microorganisms for N and P nutrition by the stoichiometric changes (%) in each grazing level relative to the no grazing treatment. Therefore, for the sustainability of grasslands in Inner Mongolia, N inputs need to be increased and high grazing intensities reduced in meadow steppe ecosystems, and the grazing load should be controlled within G0.46.
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Alados, C. L., H. Saiz, P. Nuche, M. Gartzia, B. Komac, Á. De Frutos, and Y. Pueyo. "Clearing vs. burning for restoring Pyrenean grasslands after shrub encroachment." Cuadernos de Investigación Geográfica 45, no. 2 (September 4, 2019): 441. http://dx.doi.org/10.18172/cig.3589.
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Anthropogenic activities have modified vegetation on subalpine belts for a long time, lowering the treeline ecotone and influencing the landscape mainly through grazing and fire. The abandonment of these traditional land use practices during the last decades and global warming are contributing largely to the colonization of woody species in subalpine grasslands, causing irreversible changes in ecosystem functioning. A variety of management strategies requiring the use of fire and/or clear-cutting are carried out to prevent the expansion of highly encroaching shrubs and improve the conservation status of subhumid high-productive grasslands ecosystems. However, it is still poorly understood how different management strategies affect the recovery of subalpine grasslands, which is influenced concurrently by the vegetation community involved. In this study we used field experiments to test the impact of management treatments on soil properties and vegetation responses in subalpine Bromion erecti grassland communities colonized by the pyrophyte shrub Echinospartum horridum (Vahl) Rothm. on the southern Pyrenees. Vegetation was monitored for 5 years in E. horridum plots (two plots per treatment) where the vegetation was removed by prescribed fire (Burnt treatment) or by mechanical removal (Clear-cut treatment). Undisturbed E. horridum plots were used as a control (C-Erizón) for shrub removal treatments and a Bromion erecti grassland community regularly grazed (C-Grass) was used as a control for subalpine grassland. Clear-cut treatment of E. horridum community was more effective to control E. horridum colonization than Burnt treatment and contributed to a higher extent to recover original grassland vegetation, because E. horridum seedling performed worse (lower germination rates) and plant species were more similar to the original grassland (legumes, non-legume forbs, and grasses). Shrubs and sub-shrubs cover in Burnt areas increased faster than in Clear-cut areas during the 5 years following the treatment, although it did not reach the level of C-Erizón. Species richness and diversity increased in comparison with C-Erizón in both treatments, but they were significantly lower than those in the C-Grass. Network connectivity was larger in well preserved grasslands, i.e, C-Grass, than in any other treatments, mainly dominated by negative plant-plant association. Soils nutrients declined in Burnt sites 4 years after the fire treatment and no difference was observed between Clear-cut and C-Erizón sites, although they did not reach the soil fertility values of C-Grass in terms of organic matter and C/N ratio. This study showed that grazing favors plant diversity and community complexity in subalpine grasslands. It also demonstrated that clearing is a better strategy than burning to restore grasslands after shrub encroachment because burning entails deeper soil degradation and faster recovering of the pyrophyte shrub, E. horridum.
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Carbajal-Morón, Nallely A., Mario G. Manzano, and Ricardo Mata-González. "Soil hydrology and vegetation as impacted by goat grazing in Vertisols and Regosols in semi-arid shrublands of northern Mexico." Rangeland Journal 39, no. 4 (2017): 363. http://dx.doi.org/10.1071/rj17061.
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Shrubland ecosystems are less studied than grasslands regarding the role of domestic grazing on ecosystem degradation in the world, but particularly in Mexico. Of special concern is the paucity of research on soil hydrological responses to the impact of livestock. Here, we assessed the role that specific soil and surface characteristics play in soil hydrology as a response to goat grazing intensity in two different soil types, Regosol and Vertisol, in the Tamaulipan thornscrub of north-eastern Mexico. At each soil unit, a set of grazing regimes was identified, including heavy grazing (HG), moderate grazing (MG) and a no-grazing (NG) reference area, and selected soil properties and plant cover were evaluated. In Regosol sites, soil organic matter varied among all grazing regimes (4.6% higher on NG and 2.1% higher on MG with respect HG) and no dissimilarities on bulk density were recorded. For Vertisol sites, soil bulk density increased with grazing intensity (16% higher on MG and 37% higher on HG with respect to NG) whereas plant cover linearly decreased from 86% in NG to 29% in MG and 9% in HG sites. Soil organic matter content for Regosol, and plant cover and soil bulk density for Vertisol appeared as the best indicators of water infiltration and moisture retention for the grazing conditions assessed. Differences in those key driving variables may help explain surface hydrology responses to goat grazing in rangeland soils of Tamaulipan thornscrub ecosystems and possibly on similar rangelands around the world. Clear signs of vegetation degradation were also observed, manifested by a loss in species diversity and plant cover, especially under heavy grazing. This reflects unsustainable livestock management practices that should be avoided. This study contributes to improve our understanding of rangeland degradation processes and justifies devising more sustainable grazing management schemes.
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Mavromihalis, J. A., J. Dorrough, S. G. Clark, V. Turner, and C. Moxham. "Manipulating livestock grazing to enhance native plant diversity and cover in native grasslands." Rangeland Journal 35, no. 1 (2013): 95. http://dx.doi.org/10.1071/rj12074.
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Temperate perennial grasslands globally have been subject to extensive biodiversity loss. Identifying livestock grazing regimes that maintain and enhance the diversity and cover of native plant species in these ecosystems remains a key challenge. The responses of vegetation to different sheep grazing regimes were assessed over 3 years in grasslands of south-eastern Australia. An open communal experimental design was used to assess the effects of varying season and duration of exclusion of grazing by sheep, replicated at three locations. Manipulation of season and duration of exclusion of grazing led to few major changes in the cover of native perennial grasses or forbs, although seasonal variation was considerable. Exclusion of grazing in the spring did increase the likelihood of occurrence of grazing-sensitive native forb species but also lead to an increase in the cover of exotic annual species. However, cover of exotic annual species tended to decline with increasing duration of exclusion, while the abundance of native, grazing-sensitive forbs and the cover of perennial grasses increased. Small-scale richness of native perennial forb species increased with a 3-month period of exclusion of grazing, but declined with year-round exclusion of sheep. Total species richness also declined in response to year-round exclusion of sheep and rates of decline were correlated with the rate at which herbage mass accumulated. While strategic grazing did not result in major vegetation changes in the short term, it is suggested that some grazing exclusion may enhance the survival of infrequent species most sensitive to sheep grazing. Caution, however, should be taken when grazing regimes implemented benefit both desirable (native forbs) and undesirable (exotic annuals) species. Having a mosaic of flexible grazing management regimes across the landscape is likely to be beneficial for native plant diversity.
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Van Oijen, Marcel, Zoltán Barcza, Roberto Confalonieri, Panu Korhonen, György Kröel-Dulay, Eszter Lellei-Kovács, Gaëtan Louarn, et al. "Incorporating Biodiversity into Biogeochemistry Models to Improve Prediction of Ecosystem Services in Temperate Grasslands: Review and Roadmap." Agronomy 10, no. 2 (February 12, 2020): 259. http://dx.doi.org/10.3390/agronomy10020259.
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Multi-species grasslands are reservoirs of biodiversity and provide multiple ecosystem services, including fodder production and carbon sequestration. The provision of these services depends on the control exerted on the biogeochemistry and plant diversity of the system by the interplay of biotic and abiotic factors, e.g., grazing or mowing intensity. Biogeochemical models incorporate a mechanistic view of the functioning of grasslands and provide a sound basis for studying the underlying processes. However, in these models, the simulation of biogeochemical cycles is generally not coupled to simulation of plant species dynamics, which leads to considerable uncertainty about the quality of predictions. Ecological models, on the other hand, do account for biodiversity with approaches adopted from plant demography, but without linking the dynamics of plant species to the biogeochemical processes occurring at the community level, and this hampers the models’ capacity to assess resilience against abiotic stresses such as drought and nutrient limitation. While setting out the state-of-the-art developments of biogeochemical and ecological modelling, we explore and highlight the role of plant diversity in the regulation of the ecosystem processes underlying the ecosystems services provided by multi-species grasslands. An extensive literature and model survey was carried out with an emphasis on technically advanced models reconciling biogeochemistry and biodiversity, which are readily applicable to managed grasslands in temperate latitudes. We propose a roadmap of promising developments in modelling.
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Lunt, Ian D. "Grazed, burnt and cleared: how ecologists have studied century-scale vegetation changes in Australia." Australian Journal of Botany 50, no. 4 (2002): 391. http://dx.doi.org/10.1071/bt01044.
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Ecological studies of century-scale vegetation changes in Australia were quantitatively reviewed by assessing relevant papers according to a range of methodological and environmental attributes. In general, century-scale vegetation dynamics are rarely studied by Australian ecologists. Most studies of century-scale changes are short-term studies with one sampling period, and few long-term experimental studies exist. Century-scale changes are well documented in open forests, grassy woodlands, tussock grasslands and rainforests, but little information is available from lowland heathlands, herblands or hummock grasslands. Tall open forests and rainforests have received the most comprehensive attention. Five major genres of research were recognised from a multivariate analysis of methodological attributes: (1) single-species tree-ring and fire-scar studies; (2) forest dynamics and age-structure studies; (3) floristic degradation studies (usually caused by stock grazing); (4) archival benchmarking studies; and (5) palynological research. These genres tend to focus on different ecosystems and ecosystem attributes, giving incomplete pictures of vegetation changes even in some well-studied ecosystems. In all genres other than forest dynamics studies, century-scale changes are commonly described by comparing present conditions with a pre-European reference point, and few studies have documented successive vegetation changes within the period of European occupation. Considerable opportunity exists to document long-term ecosystem responses to successive disturbances resulting from European disturbance regimes.
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Liu, Tianzeng, Zhibiao Nan, and Fujiang Hou. "Culturable autotrophic ammonia-oxidizing bacteria population and nitrification potential in a sheep grazing intensity gradient in a grassland on the Loess Plateau of Northwest China." Canadian Journal of Soil Science 91, no. 6 (November 2011): 925–34. http://dx.doi.org/10.4141/cjss2010-003.
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Liu, T., Nan, Z. and Hou, F. 2011. Culturable autotrophic ammonia-oxidizing bacteria population and nitrification potential in a sheep grazing intensity gradient in a grassland on the Loess Plateau of Northwest China. Can. J. Soil Sci. 91: 925–934. Grazing is known to enhance the activity of soil microbial communities in many types of grasslands; however, the potential impacts of rotational grazing activity on soil microbial functional groups remain poorly understood. We investigated the effects of 9 yr of rotational grazing by livestock on culturable autotrophic ammonia-oxidizing bacteria (AOB) population size, nitrification potential and soil properties in a semi-arid grassland of the Loess Plateau in Northwest China. Three stocking rate treatments of 2.7, 5.3 and 8.7 wether lambs ha−1were evaluated in geographically separated paddocks. Grazing increased nitrification potential and culturable AOB populations compared with ungrazed treatments. Ammonia-oxidizing bacteria populations increased from 155 bacteria g−1dry soil with 0 sheep ha−1to 16 218 bacteria g−1dry soil with 8.7 sheep ha−1. Grazing led to an increase in population of AOB at 0–10 cm soil depth, but had no effect on AOB at 10–20 cm soil depth. Nitrification potential increased from 1.21 mg NO3-N kg−1soil d−1in ungrazed treatments to 2.86 mg NO3-N kg−1soil d−1at the highest stocking rate. Soil ammonium and nitrate concentrations increased; however, total soil nitrogen and soil moisture content decreased with increased stocking rate for both sampling depths (0–10 cm and 10–20 cm). Soil organic matter was not affected by grazing treatments. Soil nitrification potential and the size of culturable AOB populations were dependent on grazing intensity, soil depth and season. This information is potentially important for the optimal selection of stocking rate for grazed ecosystems.
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Topalidou, Eleni, Alexandra D. Solomou, Susana S. Santos, Evdokia Krystallidou, Styliani Kakara, and Konstantinos Mantzanas. "Dynamic Role and Importance of Multi-Kingdom Communities in Mediterranean Wood-Pastures." Sustainability 13, no. 18 (September 11, 2021): 10179. http://dx.doi.org/10.3390/su131810179.
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Wood-pastures are among the most valuable types of farmland for ecosystem services, including biodiversity, landscape, soil protection, water management and cultural values. This paper reviews the scientific literature regarding the dynamic role and importance of plant, fungal and ruminant communities in Mediterranean wood-pastures and assesses the favorable and unfavorable aspects of their occurrence through grazing management. The grasslands of the Mediterranean region play an important role both in forage material production and the conservation of biodiversity in plant communities and at the landscape level. These two management purposes are not conflicting but complementary when the management is based upon the knowledge of the effect of grazing on the ecology of these ecosystems. Conclusively, vascular plant, fungal and ruminant communities have a strong influence on ecosystem structure and functioning and they play a key role in many ecological services. Hence, integrated studies which combine multi-level ecological research are essential in order to identify regional and/or national needs in terms of biodiversity, genetic resources, sustainable rural development and conservation policies.
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Vivian, L. M., K. A. Ward, D. J. Marshall, and R. C. Godfree. "Pseudoraphis spinescens (Poaceae) grasslands at Barmah Forest, Victoria, Australia: current distribution and implications for floodplain conservation." Australian Journal of Botany 63, no. 6 (2015): 526. http://dx.doi.org/10.1071/bt15090.
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Floodplain grasslands are highly productive ecosystems that are becoming increasingly degraded and fragmented because of changes to natural flood regimes. In this work, we mapped and quantified the distribution of Pseudoraphis spinescens – an ecologically important mat-forming grass – in treeless floodplain grasslands in the Barmah Forest, Victoria, Australia, across two seasons. Although P. spinescens was once widespread in the forest, there has been a decline in its extent, particularly since the Millennium Drought (2001–09) and subsequent unseasonal and prolonged La Niña-associated flooding from late 2010 to 2012. Our detailed on-ground surveys show that only 182 ha of P. spinescens grassland remain in treeless areas of Barmah Forest, representing ~12% of the total area of treeless plains and lakes. Critically, just 51 ha of the thick monospecific P. spinescens swards that were a historically important part of the floodplain vegetation was located and mapped. Although there was a small increase in the area of P. spinescens in some treeless areas following a favourable flood season in 2013–14, the boundaries of most grassland patches remained relatively stable during this period. Potential drivers of the overall decline in P. spinescens across Barmah Forest include the direct and indirect impacts of altered flood regimes, drought, and grazing pressure. Improved understanding of these drivers and their interactions, as well as the status of the seedbank, will be crucial for future management and conservation of these floodplain grasslands.
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Villalobos, Soraya, and Jana C. Vamosi. "Increasing land use drives changes in plant phylogenetic diversity and prevalence of specialists." PeerJ 4 (March 1, 2016): e1740. http://dx.doi.org/10.7717/peerj.1740.
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Increased human land use has resulted in the increased homogenization of biodiversity between sites, yet we lack sufficient indicators to predict which species decline and the consequence of their potential loss on ecosystem services. We used comparative phylogenetic analysis to (1) characterize how increasing conversion of forest and grasslands to grazing pasturelands changes plant diversity and composition; (2) examine how changes in land use relate to declines in functional trait diversity; and (3) specifically investigate how these changes in plant composition affect the prevalence of zygomorphy and the possible consequences that these changes may have on pollinator functional groups. As predicted, we found that the conversion to grazing pasturelands negatively impacted species richness and phylogenetic composition. Clades with significantly more represented taxa in grasslands (GL) were genera with a high representation of agricultural weeds, while the composition was biased towards clades of subalpine herbaceous wildflowers in Mixed Forest (MF). Changes in community composition and structure had strong effects on the prevalence of zygomorphic species likely driven by nitrogen-fixing abilities of certain clades with zygomorphic flowers (e.g., Fabaceae). Land conversion can thus have unexpected impacts on trait distributions relevant for the functioning of the community in other capacities (e.g., cascading effects to other trophic levels (i.e., pollinators). Finally, the combination of traits represented by the current composition of species in GL and MF might enhance the diagnostic value of productivity and ecosystem processes in the most eroded ecosystems.
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Yan, Huimin, Lihu Pan, Zhichao Xue, Lin Zhen, Xuehong Bai, Yunfeng Hu, and He-Qing Huang. "Agent-Based Modeling of Sustainable Ecological Consumption for Grasslands: A Case Study of Inner Mongolia, China." Sustainability 11, no. 8 (April 15, 2019): 2261. http://dx.doi.org/10.3390/su11082261.
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Sustainable ecosystem services consumption is of vital importance to the survival and development of human society. How to balance the conflicts between ecosystem protection and ecosystem services consumption by local residents has been a serious challenge, especially in ecologically vulnerable areas. To explore the reasonable ecosystem services consumption approaches of grassland ecosystems for sustainable land system management, this study takes Hulun Buir of the Inner Mongolia Autonomous Region as a case study region and develops an EcoC-G (ecological consumption of grassland) model based on herders’ livelihood behaviors using the agent-based model technique to simulate the dynamics of ecosystem pressure, livestock production, and living quality of herders under different grassland management scenarios over the next 30 years. The EcoC-G model links the supply and consumption of grassland ecosystem services by calculating the ecosystem net primary productivity (NPP) supply and household NPP consumption. The model includes three sub-models, namely, the individual status transferring sub-model, the households’ grassland-use decision sub-model, and the ecosystem pressure sub-model. In accordance with multi-objective grassland management practices, the following four land management scenarios were simulated: (1) baseline scenario, (2) increasing household’s living standard, (3) ecosystem protection, and (4) balancing living standard improvement with the protection of the ecosystem. The result indicates that by focusing on the NPP supply and consumption of the grassland ecosystem, the EcoC-G is capable of simulating the impacts of herders’ livelihood behaviors on grassland ecosystems. If timely grassland management strategies are implemented, it is possible to relieve the ecosystem pressure and improve the livelihood of local herders. The specific scenario simulation results are: (1) Under the current grassland management mode, the pasture could never be overgrazed, and herders could achieve the basic living standard, but the accumulated wealth decreased due to the decline of livestock. (2) With grazing control, herders can accumulate wealth by increasing the breeding amount and reducing the marketing rate, but the ecosystem consumption pressure can reach a maximum of 2.3 times. (3) With strict restrictions on the livestock number, the pressure on the ecosystem decreases; however, herders might not achieve basic living standards. (4) Modest regulation leads to rational ecological consumption intervals, meaning the ecosystem pressure will become stable and herders can gradually accumulate wealth with the achievement of basic living standards in advance.
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Yao, Xixi, Jianping Wu, Xuyin Gong, Xia Lang, and Cailian Wang. "Grazing exclosures solely are not the best methods for sustaining alpine grasslands." PeerJ 7 (February 22, 2019): e6462. http://dx.doi.org/10.7717/peerj.6462.
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BackgroundGrazing is widely regarded as a critical factor affecting the vegetation structure, productivity and nutritional value of natural grasslands. To protect and restore degraded grasslands, non-grazed exclosures are considered as a valuable tool. However, it is not clear whether long term non-grazed exclosures of grazers can improve the condition and nutritional value of vegetation and soil properties.MethodsWe have compared the impact of long-term non-grazed and continuous grazed management strategy on vegetation structure, nutritional values and soil properties of alpine meadow of the Qinghai-Tibet Plateau by field investigation (11–13 years) and indoor analysis during 2015–2017.ResultsOur results showed that long-term non-grazed exclosures clearly increased the aboveground biomass and coverage of plant functional types. Long-term non-grazed exclosures improved the development of all vegetation types, except NG (GG, grass species type; SG, sedge species type; LG, leguminous species type; FG, forbs species type and NG, noxious species type). Long-term non-grazed exclosures significantly improved all six measured soil properties (TN, total nitrogen; TP, total phosphorus; TK, total potassium; AN, available nitrogen; AP, available phosphorus and AK, available potassium) in 0–10 cm soil layer, considerable effect on the improvement of all measured soil properties, except TK in 10–20 cm soil layer and all measured soil properties, except TN and TK in 20–30 cm soil layer were observed. However, long-term non-grazed exclosures significantly decreased biodiversity indicators i.e., species richness, Shannon diversity index and Evenness index of vegetation. A substantial decrease in the density, biodiversity and nutritional values (CP (crude protein), IVTD (in vitroture digestibility) and NDF (neutral detergent fiber)) of all vegetation types, except NG were recorded. While a downward trend in aboveground biomass and all measured soil properties except TP and TK were observed during 2015–2017 in alpine meadows due to long-term grazed treatment. The density, diversity and nutritional value (CP and IVTD) of long-term non-grazed alpine meadows showed a downward trend over time (2015–2017). By considering the biodiversity conservation and grassland livestock production, long-term non-grazed exclosures are not beneficial for the improvement of density, biodiversity and nutritional values of plant functional types. Thus, our study suggests that rotational non-grazed and grazed treatment would be a good management strategy to restore and improve the biodiversity and nutritional values of plant functional types in natural grassland ecosystems.
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Hidy, Dóra, Zoltán Barcza, Hrvoje Marjanović, Maša Zorana Ostrogović Sever, Laura Dobor, Györgyi Gelybó, Nándor Fodor, et al. "Terrestrial ecosystem process model Biome-BGCMuSo v4.0: summary of improvements and new modeling possibilities." Geoscientific Model Development 9, no. 12 (December 7, 2016): 4405–37. http://dx.doi.org/10.5194/gmd-9-4405-2016.
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Abstract. The process-based biogeochemical model Biome-BGC was enhanced to improve its ability to simulate carbon, nitrogen, and water cycles of various terrestrial ecosystems under contrasting management activities. Biome-BGC version 4.1.1 was used as a base model. Improvements included addition of new modules such as the multilayer soil module, implementation of processes related to soil moisture and nitrogen balance, soil-moisture-related plant senescence, and phenological development. Vegetation management modules with annually varying options were also implemented to simulate management practices of grasslands (mowing, grazing), croplands (ploughing, fertilizer application, planting, harvesting), and forests (thinning). New carbon and nitrogen pools have been defined to simulate yield and soft stem development of herbaceous ecosystems. The model version containing all developments is referred to as Biome-BGCMuSo (Biome-BGC with multilayer soil module; in this paper, Biome-BGCMuSo v4.0 is documented). Case studies on a managed forest, cropland, and grassland are presented to demonstrate the effect of model developments on the simulation of plant growth as well as on carbon and water balance.
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Moinardeau, Cannelle, François Mesléard, Hervé Ramone, and Thierry Dutoit. "Short-Term Effects on Diversity and Biomass on Grasslands from Artificial Dykes under Grazing and Mowing Treatments." Environmental Conservation 46, no. 2 (October 2, 2018): 132–39. http://dx.doi.org/10.1017/s0376892918000346.
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SummaryFew studies document the impacts of conservation management practices such as extensive grazing or mowing on the new ecosystems created by industrial conversions. In southern France, the Rhône channelling led to the construction of dykes to protect the Tricastin industrialized area from floods. Aiming to control plant dynamics for safety reasons and to favour plant biodiversity, mowing or extensive grazing by cattle were recently tested. Monitoring from both permanent plots and aerial photographs shows that three years of extensive grazing and annual mechanical mowing have modified plant composition, significantly increasing plant species richness, evenness and heterogeneity. The increase in evenness and beta-diversity from grazing was significantly higher than from mowing. Only grazing was able to reduce the height and cover of the dominant tussock perennial grass species (Brachypodium phoenicoides), while increasing bare soil cover and thus the contribution of annual species. The Normalized Difference Vegetation Index (NDVI) obtained through aerial photographic analyses confirmed the correlation between NDVI, aboveground biomass and plant species richness for the grazed site alone, allowing the results obtained from quadrats to be generalized to the scale of the grazed site. On the Rhône’s artificial dykes, extensive grazing appears to be a better management tool than mowing to enhance plant biodiversity and meet safety objectives.
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Imer, D., L. Merbold, W. Eugster, and N. Buchmann. "Temporal and spatial variations of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O fluxes at three differently managed grasslands." Biogeosciences Discussions 10, no. 2 (February 14, 2013): 2635–73. http://dx.doi.org/10.5194/bgd-10-2635-2013.
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Abstract. A profound understanding of temporal and spatial variabilities of CO2, CH4 and N2O fluxes between terrestrial ecosystems and the atmosphere is needed to reliably quantify these fluxes and to develop future mitigation strategies. For managed grassland ecosystems, temporal and spatial variabilities of these three greenhouse gas (GHG) fluxes are due to environmental drivers as well as to fertilizer applications, grazing and cutting events. To assess how these affect GHG fluxes at Swiss grassland sites, we studied three sites along an altitudinal gradient that corresponds to a management gradient: from 400 m a.s.l. (intensively managed) to 1000 m a.s.l. (moderately intensive managed) to 2000 m a.s.l. (extensively managed). Temporal and spatial variabilities of GHG fluxes were quantified along small-scale transects of 16 static soil chambers at each site. We then established functional relationships between drivers and the observed fluxes on diel and annual time scales. Furthermore, spatial variabilities and their effect on representative site-specific mean chamber GHG fluxes were assessed using geostatistical semivariogram approaches. All three grasslands were N2O sources, with mean annual fluxes ranging from 0.15 to 1.28 nmol m−2 s−1. Contrastingly, all sites were net CH4 sinks, with uptake rates ranging from −0.56 to −0.15 nmol m−2 s−1. Mean annual respiration losses of CO2, as measured with opaque chambers, ranged from 5.2 to 6.5 μmol m−2 s−1. While the environmental drivers and their respective explanatory power for N2O emissions differed considerably among the three grasslands (adjusted r2 ranging from 0.19 to 0.42), CH4 and CO2 fluxes were much better constrained (adjusted r2 ranging from 0.41 to 0.83), in particular by soil water content and air temperature, respectively. Throughout the year, spatial heterogeneity was particularly high for N2O and CH4 fluxes. We found permanent hot spots for N2O emissions and CH4 uptake at the extensively managed site. Including these hot spots in calculating the mean chamber flux was essential to obtain a representative mean flux for this ecosystem. At the intensively managed grassland, management effects clearly dominated over effects of environmental drivers on N2O fluxes. For CO2 and CH4, the importance of management effects did depend on the status of the vegetation.
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Gorobtsova, Olga, Viktoria Chadaeva, Fatima Gedgafova, Tatyana Uligova, Rustam Tembotov, and Elena Khakunova. "The current state of mountain meadow soils of subalpine pasture ecosystems of the Central Caucasus (elbrus altitudinal zonality)." BIO Web of Conferences 35 (2021): 00009. http://dx.doi.org/10.1051/bioconf/20213500009.
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Intensive recreational, agricultural and logistics land use in uplands leads to their transformation and degradation. Subalpine meadow ecosystems of Central Caucasus are traditionally used for grazing and mowing. The work determined the current state of soils on pastures (mountain meadow-steppe subalpine soil and mountain meadow subalpine soil) and the level of changes of their properties under different stages of pasture degradation were defined. The efficacy of 4-stage assessment system for evaluating the pasture degradation of grasslands dominated by Bromus variegatus M. Bieb. was shown for the assessment of soil cover condition. The reduce of estimated soil indicators and degradation of soils under pastures with maximal degradation stage (DS3) of meadow ecosystems was statistically significant.
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Sanderson, M. A., S. C. Goslee, K. J. Soder, R. H. Skinner, B. F. Tracy, and A. Deak. "Plant species diversity, ecosystem function, and pasture Management—A perspective." Canadian Journal of Plant Science 87, no. 3 (July 1, 2007): 479–87. http://dx.doi.org/10.4141/p06-135.
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Grassland farmers face many challenges in pasture management including improving sustainability, reducing inputs of fertilizers and pesticides, and protecting soil resources. In this paper we provide our perspective on managing plant diversity within and among pastures as one tool to aid producers in meeting these challenges. Pasture ecosystems can be highly diverse, with a complex array of organisms contributing to ecosystem functioning. Within the broad range of plant and animal biodiversity in pastures, plant species diversity may be the most amenable to manipulation or management. Reported benefits of plant diversity in grasslands include: increased forage production, greater ecosystem stability in response to disturbance, and reduced invasion by exotic species such as weeds. Some view diversity as a sort of insurance policy where different species contribute in their own time or can take the place of species that fail from stress or mismanagement. Using mixtures of several forages in pastures, in some instances, can improve forage yield and reduce weed invasions. Pasture management for increased plant species diversity, however, is not simply mixing and planting as many forage species as possible. The kinds and amounts of different forage species along with their arrangement within and among pastures at the farm scale are critical features that must be considered. Tools must be developed to determine the appropriate species mixtures for varying soils, landscapes, climate and purposes to fulfill multiple functions for producers. Key words: Grazing ecosystem; forages; diversity; ecosystem function; ecosystem services
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Imer, D., L. Merbold, W. Eugster, and N. Buchmann. "Temporal and spatial variations of soil CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O fluxes at three differently managed grasslands." Biogeosciences 10, no. 9 (September 10, 2013): 5931–45. http://dx.doi.org/10.5194/bg-10-5931-2013.
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Abstract. A profound understanding of temporal and spatial variabilities of soil carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes between terrestrial ecosystems and the atmosphere is needed to reliably quantify these fluxes and to develop future mitigation strategies. For managed grassland ecosystems, temporal and spatial variabilities of these three soil greenhouse gas (GHG) fluxes occur due to changes in environmental drivers as well as fertilizer applications, harvests and grazing. To assess how such changes affect soil GHG fluxes at Swiss grassland sites, we studied three sites along an altitudinal gradient that corresponds to a management gradient: from 400 m a.s.l. (intensively managed) to 1000 m a.s.l. (moderately intensive managed) to 2000 m a.s.l. (extensively managed). The alpine grassland was included to study both effects of extensive management on CH4 and N2O fluxes and the different climate regime occurring at this altitude. Temporal and spatial variabilities of soil GHG fluxes and environmental drivers on various timescales were determined along transects of 16 static soil chambers at each site. All three grasslands were N2O sources, with mean annual soil fluxes ranging from 0.15 to 1.28 nmol m−2 s−1. Contrastingly, all sites were weak CH4 sinks, with soil uptake rates ranging from −0.56 to −0.15 nmol m−2 s−1. Mean annual soil and plant respiration losses of CO2, measured with opaque chambers, ranged from 5.2 to 6.5 μmol m−2 s−1. While the environmental drivers and their respective explanatory power for soil N2O emissions differed considerably among the three grasslands (adjusted r2 ranging from 0.19 to 0.42), CH4 and CO2 soil fluxes were much better constrained (adjusted r2 ranging from 0.46 to 0.80) by soil water content and air temperature, respectively. Throughout the year, spatial heterogeneity was particularly high for soil N2O and CH4 fluxes. We found permanent hot spots for soil N2O emissions as well as locations of permanently lower soil CH4 uptake rates at the extensively managed alpine site. Including hot spots was essential to obtain a representative mean soil flux for the respective ecosystem. At the intensively managed grassland, management effects clearly dominated over effects of environmental drivers on soil N2O fluxes. For CO2 and CH4, the importance of management effects did depend on the status of the vegetation (LAI).
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De Vroey, Mathilde, Julien Radoux, and Pierre Defourny. "Grassland Mowing Detection Using Sentinel-1 Time Series: Potential and Limitations." Remote Sensing 13, no. 3 (January 20, 2021): 348. http://dx.doi.org/10.3390/rs13030348.
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Grasslands encompass vast and diverse ecosystems that provide food, wildlife habitat and carbon storage. Their large range in land use intensity significantly impacts their ecological value and the balance between these goods and services. Mowing dates and frequencies are major aspects of grassland use intensity, which have an impact on their ecological value as habitats. Previous studies highlighted the feasibility of detecting mowing events based on remote sensing time series, a few of which using synthetic aperture radar (SAR) imagery. Although providing encouraging results, research on grassland mowing detection often lacks sufficient precise reference data for corroboration. The goal of the present study is to quantitatively and statistically assess the potential of Sentinel-1 C-band SAR for detecting mowing events in various agricultural grasslands, using a large and diverse reference data set collected in situ. Several mowing detection methods, based on SAR backscattering and interferometric coherence time series, were thoroughly evaluated. Results show that 54% of mowing events could be detected in hay meadows, based on coherence jumps. Grazing events were identified as a major confounding factor, as most false detections were made in pastures. Parcels with one mowing event in the summer were identified with the highest accuracy (71%). Overall, this study demonstrates that mowing events can be detected through Sentinel-1 coherence. However, the performances could probably be further enhanced by discriminating pastures beforehand and combining Sentinel-1 and Sentinel-2 data for mowing detection.
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Zhong, Lei, Shiping Wang, Xingliang Xu, Yanfen Wang, Yichao Rui, Xiaoqi Zhou, Qinhua Shen, et al. "Fungi regulate the response of the N<sub>2</sub>O production process to warming and grazing in a Tibetan grassland." Biogeosciences 15, no. 14 (July 20, 2018): 4447–57. http://dx.doi.org/10.5194/bg-15-4447-2018.
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Abstract. Lack of understanding of the effects of warming and winter grazing on soil fungal contribution to the nitrous oxide (N2O) production process has limited our ability to predict N2O fluxes under changes in climate and land use management, because soil fungi play an important role in driving terrestrial N cycling. A controlled warming and winter grazing experiment that included control (C), winter grazing (G), warming (W) and warming with winter grazing (WG) was conducted to investigate the effects of warming and winter grazing on soil N2O production potential in an alpine meadow on the Tibetan Plateau. Our results showed that soil bacteria and fungi contributed 46 ± 2 % and 54 ± 2 % to nitrification, and 37 ± 3 % and 63 ± 3 % to denitrification in the control treatment, respectively. We conclude that soil fungi could be the main source of N2O production potential for the Tibetan alpine grasslands. In our results, neither warming nor winter grazing affected the activity of enzymes responsible for overall nitrification and denitrification. However, warming significantly increased the enzyme activity of bacterial nitrification and potential of N2O production from denitrification to 53 ± 2 % and 55 ± 3 %, respectively, but decreased them to 47 ± 2 % and 45 ± 3 %, respectively. Winter grazing had no such effects. Warming and winter grazing may not affect the soil N2O production potential, but climate warming can alter biotic pathways responsible for N2O production process. These findings confirm the importance of soil fungi in the soil N2O production process and how they respond to environmental and land use changes in alpine meadow ecosystems. Therefore, our results provide some new insights into ecological controls on the N2O production process and contribute to the development of an ecosystem nitrogen cycle model.
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Dovrat, Guy, Efrat Sheffer, Serge Yan Landau, Tova Deutch, Haim Gorelik, and Zalmen Henkin. "Can Grazing Moderate Climatic Effects on Herbage Nutritional Quality?" Agronomy 11, no. 4 (April 7, 2021): 700. http://dx.doi.org/10.3390/agronomy11040700.
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In Mediterranean grasslands, the composition of vegetation and its nutritional quality for animals are strongly affected by the climatic conditions prevailing during winter and spring. Therefore, these seasonal ecosystems provide an opportunity to examine how variability in climatic conditions affects the regeneration and quality of pasture vegetation. The intensity of grazing in this seasonal system can moderate, or alternatively exacerbate, climatic effects on the nutritional quality of the vegetation. Herein, we analyzed the interactive effects of climate variables, grazing intensity, and grazing exclusion on herbage quality parameters using long-term vegetation and climate data collected during 2005–2018 from an extensive experiment in Galilee, Israel. We evaluated the contribution of different climate variables to the prediction of herbage quality parameters. Our results showed that climate variables have a dramatic effect on herbage quality and that this effect interacts with grazing intensity. Herbage quality improved in temperate rainy years compared to warm and dry years. High grazing intensity improved herbage quality under temperate climate conditions, but this effect was moderated or completely disappeared as winter conditions become warmer and drier. The results of the study foresee negative effects of warming and drying on the carrying capacity of natural pastures.
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Geremia, Chris, Jerod A. Merkle, Daniel R. Eacker, Rick L. Wallen, P. J. White, Mark Hebblewhite, and Matthew J. Kauffman. "Migrating bison engineer the green wave." Proceedings of the National Academy of Sciences 116, no. 51 (November 21, 2019): 25707–13. http://dx.doi.org/10.1073/pnas.1913783116.
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Newly emerging plants provide the best forage for herbivores. To exploit this fleeting resource, migrating herbivores align their movements to surf the wave of spring green-up. With new technology to track migrating animals, the Green Wave Hypothesis has steadily gained empirical support across a diversity of migratory taxa. This hypothesis assumes the green wave is controlled by variation in climate, weather, and topography, and its progression dictates the timing, pace, and extent of migrations. However, aggregate grazers that are also capable of engineering grassland ecosystems make some of the world’s most impressive migrations, and it is unclear how the green wave determines their movements. Here we show that Yellowstone’s bison (Bison bison) do not choreograph their migratory movements to the wave of spring green-up. Instead, bison modify the green wave as they migrate and graze. While most bison surfed during early spring, they eventually slowed and let the green wave pass them by. However, small-scale experiments indicated that feedback from grazing sustained forage quality. Most importantly, a 6-fold decadal shift in bison density revealed that intense grazing caused grasslands to green up faster, more intensely, and for a longer duration. Our finding broadens our understanding of the ways in which animal movements underpin the foraging benefit of migration. The widely accepted Green Wave Hypothesis needs to be revised to include large aggregate grazers that not only move to find forage, but also engineer plant phenology through grazing, thereby shaping their own migratory movements.
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Wei, Xiaoxu, Changzhen Yan, and Wei Wei. "Grassland Dynamics and the Driving Factors Based on Net Primary Productivity in Qinghai Province, China." ISPRS International Journal of Geo-Information 8, no. 2 (February 2, 2019): 73. http://dx.doi.org/10.3390/ijgi8020073.
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Qinghai province is an important part of the Tibetan Plateau, and is characterized by extremely fragile ecosystems. In the last few decades, grasslands in this province have been influenced profoundly by climate change, as well as human activities. Here, we use the Carnegie-Ames-Stanford Approach (CASA) model to assess the dynamics of temperate steppe, alpine steppe, temperate meadow, alpine meadow, sparse grassland and herbaceous wetland via actual net primary productivity (NPPa). Our findings showed that: (1) From 2001 to 2016, the average NPPa in Qinghai province showed a fluctuation presented a generally increasing trend. The mean value of NPPa was 114.27 g C m−2 year−1, and the increase rate was 0.47 g C cm−2 year−1. (2) There were NPPa increase rate discrepancies among the six typical grassland biomes. Herbaceous wetland had the highest change rate, closely followed by alpine steppe, temperate steppe, alpine meadow, temperate meadow and sparse grassland. (3) The largest area of restoration mainly impacted by climate change reached 47.08% of the total grassland area, with human activities accounting for 21.74%. By contrast, the deteriorated area induced by human activities accounted for 9.78% of the total grassland. (4) Temperature may have been a greater factor than precipitation in driving grassland change during the study period. Decreasing grazing intensity and implementing effective protection measures were favorable to grassland restoration.
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Pettigrew, Melissa, and C. Michael Bull. "The impact of heavy grazing on burrow choice in the pygmy bluetongue lizard, Tiliqua adelaidensis." Wildlife Research 38, no. 4 (2011): 299. http://dx.doi.org/10.1071/wr11052.
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Context Grazing pressure has directly altered and indirectly influenced natural ecosystems worldwide, and has affected and displaced many native species. The endangered pygmy bluetongue lizard Tiliqua adelaidensis is endemic to the mid-north of South Australia. It inhabits remnant native grasslands where it is reliant on the presence of natural spider burrows constructed by lycosid and mygalomorph spiders as refuge sites. These lizards spend the majority of the day associated with their burrow either in the burrow itself or basking at its entrance. The remnant native grasslands of South Australia have endured 200 years of agricultural changes and the introduction of domestic stock has meant that grazing pressure has substantially increased. The vegetation around a burrow is considered to be important in providing shelter for the lizard. However, too much vegetation may reduce basking opportunities and visibility of prey. Stock grazing has been maintained on the majority of sites that contain pygmy bluetongue populations and it is presumed that the lizards can tolerate some form of grazing. However, the level of grazing intensity directly influences the vegetation structure that surrounds the lizard burrows. Aims We aimed to investigate the consequences of severe grazing pressure on the choice of burrows by lizards, and on their burrow related behaviour. Methods We simulated heavy grazing pressure by manually removing aboveground vegetation in the field in replicated quadrats that contained artificial burrows, and by providing bare substrate in half of experimental enclosures in the laboratory. Key results In the field, lizards only occupied the artificial burrows in control quadrats, where vegetation had been left intact. In the laboratory, lizards that occupied both burrows basked for longer at the burrow entrance where vegetation was present. Conclusions Heavy grazing management that results in the majority of vegetation being removed could have a negative impact on pygmy bluetongue lizard recruitment and sustainability. Implications Grazing regimes should be carefully monitored to consider the needs of species that rely heavily on microhabitat structure for their persistence. For the endangered pygmy bluetongue lizard, heavy grazing should be avoided to promote amounts of vegetation suitable to sustain viable populations.
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Thomas, Andrew D. "Impact of grazing intensity on seasonal variations in soil organic carbon and soil CO 2 efflux in two semiarid grasslands in southern Botswana." Philosophical Transactions of the Royal Society B: Biological Sciences 367, no. 1606 (November 19, 2012): 3076–86. http://dx.doi.org/10.1098/rstb.2012.0102.
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Biological soil crusts (BSCs) are an important source of organic carbon, and affect a range of ecosystem functions in arid and semiarid environments. Yet the impact of grazing disturbance on crust properties and soil CO 2 efflux remain poorly studied, particularly in African ecosystems. The effects of burial under wind-blown sand, disaggregation and removal of BSCs on seasonal variations in soil CO 2 efflux, soil organic carbon, chlorophyll a and scytonemin were investigated at two sites in the Kalahari of southern Botswana. Field experiments were employed to isolate CO 2 efflux originating from BSCs in order to estimate the C exchange within the crust. Organic carbon was not evenly distributed through the soil profile but concentrated in the BSC. Soil CO 2 efflux was higher in Kalahari Sand than in calcrete soils, but rates varied significantly with seasonal changes in moisture and temperature. BSCs at both sites were a small net sink of C to the soil. Soil CO 2 efflux was significantly higher in sand soils where the BSC was removed, and on calcrete where the BSC was buried under sand. The BSC removal and burial under sand also significantly reduced chlorophyll a , organic carbon and scytonemin . Disaggregation of the soil crust, however, led to increases in chlorophyll a and organic carbon. The data confirm the importance of BSCs for C cycling in drylands and indicate intensive grazing, which destroys BSCs through trampling and burial, will adversely affect C sequestration and storage. Managed grazing, where soil surfaces are only lightly disturbed, would help maintain a positive carbon balance in African drylands.
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Li, Meng, Jianshuang Wu, Chunqiao Song, Yongtao He, Ben Niu, Gang Fu, Paolo Tarolli, Britta Tietjen, and Xianzhou Zhang. "Temporal Variability of Precipitation and Biomass of Alpine Grasslands on the Northern Tibetan Plateau." Remote Sensing 11, no. 3 (February 11, 2019): 360. http://dx.doi.org/10.3390/rs11030360.
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The timing regimes of precipitation can exert profound impacts on grassland ecosystems. However, it is still unclear how the peak aboveground biomass (AGBpeak) of alpine grasslands responds to the temporal variability of growing season precipitation (GSP) on the northern Tibetan Plateau. Here, the temporal variability of precipitation was defined as the number and intensity of precipitation events as well as the time interval between consecutive precipitation events. We conducted annual field measurements of AGBpeak between 2009 and 2016 at four sites that were representative of alpine meadow, meadow-steppe, alpine steppe, and desert-steppe. Thus, an empirical model was established with the time series of the field-measured AGBpeak and the corresponding enhanced vegetation index (EVI) (R2 = 0.78), which was used to estimate grassland AGBpeak at the regional scale. The relative importance of the three indices of the temporal variability of precipitation, events, intensity, and time interval on grassland AGBpeak was quantified by principal component regression and shown in a red–green–blue (RGB) composition map. The standardized importance values were used to calculate the vegetation sensitivity index to the temporal variability of precipitation (VSIP). Our results showed that the standardized VSIP was larger than 60 for only 15% of alpine grassland pixels and that AGBpeak did not change significantly for more than 60% of alpine grassland pixels over the past decades, which was likely due to the nonsignificant changes in the temporal variability of precipitation in most pixels. However, a U-shaped relationship was found between VSIP and GSP across the four representative grassland types, indicating that the sensitivity of grassland AGBpeak to precipitation was dependent on the types of grassland communities. Moreover, we found that the temporal variability of precipitation explained more of the field-measured AGBpeak variance than did the total amount of precipitation alone at the site scale, which implies that the mechanisms underlying how the temporal variability of precipitation controls the AGBpeak of alpine grasslands should be better understood at the local scale. We hypothesize that alpine grassland plants promptly respond to the temporal variability of precipitation to keep community biomass production more stable over time, but this conclusion should be further tested. Finally, we call for a long-term experimental study that includes multiple natural and anthropogenic factors together, such as warming, nitrogen deposition, and grazing and fencing, to better understand the mechanisms of alpine grassland stability on the Tibetan Plateau.
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Vacchiano, Giorgio, Cristiano Foderi, Roberta Berretti, Enrico Marchi, and Renzo Motta. "Modeling anthropogenic and natural fire ignitions in an inner-alpine valley." Natural Hazards and Earth System Sciences 18, no. 3 (March 23, 2018): 935–48. http://dx.doi.org/10.5194/nhess-18-935-2018.
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Abstract. Modeling and assessing the factors that drive forest fire ignitions is critical for fire prevention and sustainable ecosystem management. In southern Europe, the anthropogenic component of wildland fire ignitions is especially relevant. In the Alps, however, the role of fire as a component of disturbance regimes in forest and grassland ecosystems is poorly known. The aim of this work is to model the probability of fire ignition for an Alpine region in Italy using a regional wildfire archive (1995–2009) and MaxEnt modeling. We analyzed separately (i) winter forest fires, (ii) winter fires on grasslands and fallow land, and (iii) summer fires. Predictors were related to morphology, climate, and land use; distance from infrastructures, number of farms, and number of grazing animals were used as proxies for the anthropogenic component. Collinearity among predictors was reduced by a principal component analysis. Regarding ignitions, 30 % occurred in agricultural areas and 24 % in forests. Ignitions peaked in the late winter–early spring. Negligence from agrosilvicultural activities was the main cause of ignition (64 %); lightning accounted for 9 % of causes across the study time frame, but increased from 6 to 10 % between the first and second period of analysis. Models for all groups of fire had a high goodness of fit (AUC 0.90–0.95). Temperature was proportional to the probability of ignition, and precipitation was inversely proportional. Proximity from infrastructures had an effect only on winter fires, while the density of grazing animals had a remarkably different effect on summer (positive correlation) and winter (negative) fires. Implications are discussed regarding climate change, fire regime changes, and silvicultural prevention. Such a spatially explicit approach allows us to carry out spatially targeted fire management strategies and may assist in developing better fire management plans.
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Smith, Alistair M. S., Alan F. Talhelm, Crystal A. Kolden, Beth A. Newingham, Henry D. Adams, Jack D. Cohen, Kara M. Yedinak, and Robert L. Kremens. "The ability of winter grazing to reduce wildfire size and fire-induced plant mortality was not demonstrated: a comment on Davies et al. (2015)." International Journal of Wildland Fire 25, no. 4 (2016): 484. http://dx.doi.org/10.1071/wf15163.
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A recent study by Davies et al. sought to test whether winter grazing could reduce wildfire size, fire behaviour and intensity metrics, and fire-induced plant mortality in shrub–grasslands. The authors concluded that ungrazed rangelands may experience fire-induced mortality of native perennial bunchgrasses. The authors also presented several statements regarding the benefits of winter grazing on post-fire plant community responses. However, we contend that the study by Davies et al. has underlying methodological errors, lacks data necessary to support their conclusions, and does not provide a thorough discussion on the effect of grazing on rangeland ecosystems. Importantly, Davies et al. presented no data on the post-fire mortality of the perennial bunchgrasses or on the changes in plant community composition following their experimental fires. Rather, Davies et al. inferred these conclusions based on their observed fire behaviour metrics of maximum temperature and a term described as the ‘heat load’. However, we contend that neither metric is appropriate for describing the heat flux impacts on plants. This lack of post-fire data, several methodological errors and the use of inappropriate thermal metrics limit the authors’ ability to support their stated conclusions.
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Foreman, Paul Warrick. "Recovery of the Northern Plains Grassland Community – an overview." Proceedings of the Royal Society of Victoria 122, no. 2 (2010): 92. http://dx.doi.org/10.1071/rs10018.
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The grasslands of the northern plains of Victoria have long been recognised to be among the most threatened and poorly-reserved ecosystems in Victoria and Australia with only an estimated 3.8% remaining. As the protected area network (PAN) has greatly expanded in the last decade, there has been a commensurate loss of unprotected grasslands due to legal and illegal clearing. Whether or not the PAN continues to grow, there is now a significant on-going conservation management liability that must be underpinned by an improved understanding of ecosystem function and the role of disturbance. Some encouraging progress has been made by recent research. For instance, only partial recovery from cultivation is possible with long (cultivation) resting and that further improvement requires intervention to overcome the limits in seed dispersal of key functional groups. And although more has been learnt about how patterns in productivity/species-richness interactions can be managed/influenced by biomass manipulation, the use of stock grazing as a sustainable conservation management tool has still not been demonstrated. The interim regime of ‘status quo’ (stock) management persists despite the fact that it has failed to: (a) differentiate itself from standard pastoral practices, and (b) define the pathway to discovering better alternatives. A new technical advisory group has been established to oversee recovery strategy and has chosen the development of a ‘conceptual model of how the system works’, as a key priority. A further priority will be to pursue the renomination of the community under the Environment Protection and Biodiversity Conservation Act 1999 following the recent publication of research suggesting these grasslands are naturally treeless, floristically unique and geographically confined to the southern Riverina.
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Norbury, Grant, Richard Heyward, and John Parkes. "Short-term ecological effects of rabbit haemorrhagic disease in the short-tussock grasslands of the South Island, New Zealand." Wildlife Research 29, no. 6 (2002): 599. http://dx.doi.org/10.1071/wr00085.
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Rabbit haemorrhagic disease (RHD) has reduced populations of rabbits (Oryctolagus cuniculus) across most rabbit-prone short-tussock grasslands of New Zealand, at scales rarely seen there before. Flow-on effects to other parts of these ecosystems will be inevitable. We report evidence for increases in pasture biomass, increases in abundance of other exotic herbivores, declines in abundance of rabbit-specialist predators, and short-term increases in predation rates of some native birds by these predators. At one site in Central Otago, RHD reduced an index of rabbit abundance by 88%, and an index of their grazing impacts by 77%. Recovered biomass consisted mostly of fast-growing exotic pasture species of moderate palatability to livestock. Spotlight counts and hunters' returns suggest increases in possum (Trichosurus vulpecula) and hare (Lepus europeaus) abundance, but their grazing pressure is unlikely to replace that originally imposed by rabbits. The apparent increase in possum numbers poses an increased risk from the spread and maintenance of bovine tuberculosis (Tb), although this risk may be offset by declines in the counts of ferrets (Mustela furo), which also carry Tb. Declines in predator numbers (including feral cats, Felis catus) may also, in the longer term, benefit some native fauna that are secondary prey of these predators. There is evidence for increased predation of some native birds' eggs since RHD arrived. It is not possible at this stage to generalise the effects of RHD-induced declines in rabbit abundance on New Zealand ecosystems. Effects are highly variable, and their implications for pastoral production, management of bovine Tb, and conservation of native species are likely to vary locally according to the suite of plant and animal species originally present.
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Théau, Jérôme, Étienne Lauzier-Hudon, Lydiane Aubé, and Nicolas Devillers. "Estimation of forage biomass and vegetation cover in grasslands using UAV imagery." PLOS ONE 16, no. 1 (January 25, 2021): e0245784. http://dx.doi.org/10.1371/journal.pone.0245784.
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Grasslands are among the most widespread ecosystems on Earth and among the most degraded. Their characterization and monitoring are generally based on field measurements, which are incomplete spatially and temporally. The recent advent of unmanned aerial vehicles (UAV) provides data at unprecedented spatial and temporal resolutions. This study aims to test and compare three approaches based on multispectral imagery acquired by UAV to estimate forage biomass or vegetation cover in grasslands. The study site is composed of 30 pasture plots (25 × 50 m), 5 bare soil plots (25 x 50), and 6 control plots (5 × 5 m) on a 14-ha field maintained at various biomass levels by grazing rotations and clipping over a complete growing season. A total of 14 flights were performed. A first approach based on structure from motion was used to generate a volumetric-based biomass estimation model (R2 of 0.93 and 0.94 for fresh biomass [FM] and dry biomass [DM], respectively). This approach is not very sensitive to low vegetation levels but is accurate for FM estimation greater than 0.5 kg/m2 (0.1 kg DM/m2). The Green Normalized Difference Vegetation Index (GNDVI) was selected to develop two additional approaches. One is based on a regression biomass prediction model (R2 of 0.80 and 0.66 for FM and DM, respectively) and leads to an accurate estimation at levels of FM lower than 3 kg/m2 (0.6 kg DM/m2). The other approach is based on a classification of vegetation cover from clustering of GNDVI values in four classes. This approach is more qualitative than the other ones but more robust and generalizable. These three approaches are relatively simple to use and applicable in an operational context. They are also complementary and can be adapted to specific applications in grassland characterization.