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Zhou, Yanqing, Yaoming Li, Wei Li, Feng Li e Qinchuan Xin. "Ecological Responses to Climate Change and Human Activities in the Arid and Semi-Arid Regions of Xinjiang in China". Remote Sensing 14, n. 16 (12 agosto 2022): 3911. http://dx.doi.org/10.3390/rs14163911.
Testo completoAbstract (sommario):
Understanding the impacts and extent of both climate change and human activities on ecosystems is crucial to sustainable development. With low anti-interference ability, arid and semi-arid ecosystems are particularly sensitive to disturbances from both climate change and human activities. We investigated how and to what extent climate variation and human activities influenced major indicators that are related to ecosystem functions and conditions in the past decades in Xinjiang, a typical arid and semi-arid region in China. We analyzed the changing trends of evapotranspiration (ET), gross primary productivity (GPP) and leaf area index (LAI) derived from the Moderate-Resolution Imaging Spectroradiometer (MODIS) satellite product and the Breathing Earth System Simulator (BESS) model in Xinjiang for different climate zones. We separated and quantified the contributions of climate forcing and human activities on the trends of the studied ecosystem indicators using the residual analysis method for different climate zones in Xinjiang. The results show that GPP and LAI increased and ET decreased from 2001 to 2015 in Xinjiang. Factors that dominate the changes in ecosystem indicators vary considerably across different climate zones. Precipitation plays a positive role in impacting vegetation indicators in arid and hyper-arid zones and temperature has a negative correlation with both GPP and LAI in hyper-arid zones in Xinjiang. Results based on residual analysis indicate that human activities could account for over 72% of variation in the changes in each ecosystem indicator. Human activities have large impacts on each vegetation indicator change in hyper-arid and arid zones and their relative contribution has a mean value of 79%. This study quantifies the roles of climate forcing and human activities in the changes in ecosystem indicators across different climate zones, suggesting that human activities largely influence ecosystem processes in the arid and semi-arid regions of Xinjiang in China.
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Cai, Peng, Chaofan Li, Geping Luo, Chi Zhang, Friday Uchenna Ochege, Steven Caluwaerts, Lesley De Cruz et al. "The Responses of the Ecosystems in the Tianshan North Slope under Multiple Representative Concentration Pathway Scenarios in the Middle of the 21st Century". Sustainability 12, n. 1 (6 gennaio 2020): 427. http://dx.doi.org/10.3390/su12010427.
Testo completoAbstract (sommario):
The arid ecosystem is fragile and sensitive to the changes in climate and CO2 concentration. Exploring the responses of the arid ecosystem to the changes under different representative concentration pathways (RCPs) is of particular significance for the sustainable development of the ecosystem. In this study, the dynamics of net primary productivity (NPP), evapotranspiration (ET), and water use efficiency (WUE) for arid ecosystems in Tianshan North Slope are explored by running the arid ecosystem model at 25 km resolution under RCP2.6, RCP4.5, and RCP8.5. The climate in Tianshan North Slope presents a wet-warming trend during 2006–2055 under each RCP scenario with temporal and spatial heterogeneity. In response to the changes in climate and CO2, the regional annual NPP and ET increased during 2006–2055 by a respectively maximum rate of 2.15 g C m−2 year−1 and 0.52 mm year−1 under RCP8.5. Both the NPP and ET share a similar temporal and spatial heterogeneity with climate change. Different vegetation types respond differently to the changes under different RCP scenarios with increasing WUE. Under each RCP, the non-phreatophyte, phreatophyte, and grass are more sensitive to the changes than in the others, and the broadleaf forest and cropland are less sensitive to the changes.
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Fan, Xue, Xingming Hao, Haichao Hao, Jingjing Zhang e Yuanhang Li. "Comprehensive Assessment Indicator of Ecosystem Resilience in Central Asia". Water 13, n. 2 (7 gennaio 2021): 124. http://dx.doi.org/10.3390/w13020124.
Testo completoAbstract (sommario):
The ecosystems in the arid inland areas of Central Asia are fragile and severely degraded. Understanding and assessing ecosystem resilience is a challenge facing ecosystems. Based on the net primary productivity (NPP) data estimated by the CASA model, this study conducted a quantitative analysis of the ecosystem’s resilience and comprehensively reflected its resilience from multiple dimensions. Furthermore, a comprehensive resilience index was constructed. The result showed that plain oasis’s ecosystem resilience is the highest, followed by deserts and mountainous areas. From the perspective of vegetation types, the highest resilience is artificial vegetation and the lowest is forest. In warm deserts, the resilience is higher in shrubs and meadows and lower in grassland vegetation. High coverage and biomass are not the same as the strong adaptability of the ecosystem. Moderate and slightly inelastic areas mainly dominate the ecosystem resilience of the study area. The new method is easy to use. The evaluation result is reliable. It can quantitatively analyze the resilience latitude and recovery rate, a beneficial improvement to the current ecosystem resilience evaluation.
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Fan, Xue, Xingming Hao, Haichao Hao, Jingjing Zhang e Yuanhang Li. "Comprehensive Assessment Indicator of Ecosystem Resilience in Central Asia". Water 13, n. 2 (7 gennaio 2021): 124. http://dx.doi.org/10.3390/w13020124.
Testo completoAbstract (sommario):
The ecosystems in the arid inland areas of Central Asia are fragile and severely degraded. Understanding and assessing ecosystem resilience is a challenge facing ecosystems. Based on the net primary productivity (NPP) data estimated by the CASA model, this study conducted a quantitative analysis of the ecosystem’s resilience and comprehensively reflected its resilience from multiple dimensions. Furthermore, a comprehensive resilience index was constructed. The result showed that plain oasis’s ecosystem resilience is the highest, followed by deserts and mountainous areas. From the perspective of vegetation types, the highest resilience is artificial vegetation and the lowest is forest. In warm deserts, the resilience is higher in shrubs and meadows and lower in grassland vegetation. High coverage and biomass are not the same as the strong adaptability of the ecosystem. Moderate and slightly inelastic areas mainly dominate the ecosystem resilience of the study area. The new method is easy to use. The evaluation result is reliable. It can quantitatively analyze the resilience latitude and recovery rate, a beneficial improvement to the current ecosystem resilience evaluation.
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Mugari, Ephias, Hillary Masundire, Maitseo Bolaane e Mark New. "Perceptions of ecosystem services provision performance in the face of climate change among communities in Bobirwa sub-district, Botswana". International Journal of Climate Change Strategies and Management 11, n. 2 (8 marzo 2019): 265–88. http://dx.doi.org/10.1108/ijccsm-09-2017-0178.
Testo completoAbstract (sommario):
PurposeBetween 2006 and 2016, local communities in semi-arid Bobirwa sub-district in the Limpopo Basin part of Botswana had endured notable fluctuations in the delivery of critical ecosystem services. These changes have been coupled with adverse effects on local people’s livelihood options and well-being. However, a few such studies have focussed on the semi-arid to arid landscapes. This study therefore aims to provide recent knowledge and evidence of consequences of environmental change on semi-arid arid landscapes and communities.MethodologyTo examine these recent changes in key ecosystem services, the authors conducted six participatory mapping processes, eight key informant interviews and several rapid scoping appraisals in three study villages. The analyses were centred on changes in seasonal quantities, seasonality, condition of ecosystem service sites, distance to ecosystem service sites and total area providing these services. Drivers of change in the delivery of key ecosystem services and the associated adverse impacts on human well-being of these recent changes in bundles of ecosystem services delivered were also analyzed.FindingsResults show that adverse weather conditions, drought frequency, changes in land-use and/or land-cover together with unsustainable harvesting because of human influx on local resources have intensified in the past decade. There was circumstantial evidence that these drivers have resulted in adverse changes in quantities and seasonality of key ecosystem services such as edible Mopane caterpillars, natural pastures, wild fruits and cultivated crops. Similarly, distance to, condition and total area of sites providing some of the key ecosystem services such as firewood and natural pastures changed adversely. These adverse changes in the key ecosystem services were shown to increasingly threaten local livelihoods and human well-being.Research limitations/implicationsThis paper discusses the importance of engaging rural communities in semi-arid areas in a participatory manner and how such information can provide baseline information for further research. The paper also shows the utility of such processes and information toward integrating community values and knowledge into decisions regarding the management and utilization of local ecosystem services under a changing climate in data-poor regions such as the Bobirwa sub-district of Botswana. However, the extent to which this is possible depends on the decision makers’ willingness to support local initiatives through existing government structures and programmes.Originality/valueThis study shows the importance of engaging communities in a participatory manner to understand changes in local ecosystem services considering their unique connection with the natural environment. This is a critical step for decision makers toward integrating community values in the management and utilization of ecosystem services under a changing climate as well as informing more sustainable adaptive responses in semi-arid areas. However, the extent to which decision makers can integrate such findings to inform more sustainable responses to declining capacity of local ecosystems in semi-arid areas depends on how they value the bottom-up approach of gaining local knowledge as well as their willingness to support local initiatives through existing government structures and programmes.
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Guan, K., S. P. Good, K. K. Caylor, H. Sato, E. F. Wood e H. Li. "Continental-scale impacts of intra-seasonal rainfall variability on simulated ecosystem responses in Africa". Biogeosciences 11, n. 23 (11 dicembre 2014): 6939–54. http://dx.doi.org/10.5194/bg-11-6939-2014.
Testo completoAbstract (sommario):
Abstract. Climate change is expected to modify intra-seasonal rainfall variability, arising from shifts in rainfall frequency, intensity and seasonality. These intra-seasonal changes are likely to have important ecological impacts on terrestrial ecosystems. Yet, quantifying these impacts across biomes and large climate gradients is largely missing. This gap hinders our ability to better predict ecosystem services and their responses to climate change, especially for arid and semi-arid ecosystems. Here we use a synthetic weather generator and an independently validated vegetation dynamic model (SEIB-Dynamic Global Vegetation Model, DGVM) to virtually conduct a series of "rainfall manipulation experiments" to study how changes in the intra-seasonal rainfall variability affect continent-scale ecosystem responses across Africa. We generate different rainfall scenarios with fixed total annual rainfall but shifts in (i) frequency vs. intensity, (ii) rainy season length vs. frequency, (iii) intensity vs. rainy season length. These scenarios are fed into SEIB-DGVM to investigate changes in biome distributions and ecosystem productivity. We find a loss of ecosystem productivity with increased rainfall frequency and decreased intensity at very low rainfall regimes (<400 mm year−1) and low frequency (<0.3 event day−1); beyond these very dry regimes, most ecosystems benefit from increased frequency and decreased intensity, except in the wet tropics (>1800 mm year−1) where radiation limitation prevents further productivity gains. This result reconciles seemingly contradictory findings in previous field studies on the impact of rainfall frequency/intensity on ecosystem productivity. We also find that changes in rainy season length can yield more dramatic ecosystem responses compared with similar percentage changes in rainfall frequency or intensity, with the largest impacts in semi-arid woodlands. This study demonstrates that intra-seasonal rainfall characteristics play a significant role in influencing ecosystem function and structure through controls on ecohydrological processes. Our results suggest that shifts in rainfall seasonality have potentially large impacts on terrestrial ecosystems, and these understudied impacts should be explicitly examined in future studies of climate impacts.
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Alqallaf, Ahmed, Bader Al-Anzi e Meshal Alabdullah. "Assessing the Effectiveness of Supplemental Irrigation to Improve Soil Moisture in an Arid Ecosystem with an Emphasis on Climate Change: A Case Study from the State of Kuwait". Sustainability 12, n. 21 (1 novembre 2020): 9104. http://dx.doi.org/10.3390/su12219104.
Testo completoAbstract (sommario):
Arid ecosystems are extremely vulnerable to climate change, which is considered one of the serious global environmental issues that can cause critical challenges to the hydrological cycle in arid ecosystems. This work focused on assessing the effectiveness of supplemental irrigation to improve the actual soil moisture content in arid ecosystems and considering climate change impacts on soil moisture. The study was conducted at two fenced protected sites in Kuwait. The first site is naturally covered with Rhanterietum epapposum, whereas the other study site is a supplemented irrigated site, containing several revegetated native plants. The results showed that supplemental irrigation highly improved soil moisture (∆SM) during the winter season by >50%. However, during the summer season, the rainfed and irrigated site showed low ∆SM due to the high temperature and high evapotranspiration (ET) rates. We also found that ∆SM would negatively get impacted by climate change. The climate change projection results showed that temperature would increase by 12%–23%, ET would increase by 17%–19%, and precipitation would decrease by 31%–46% by 2100. Such climate change impacts may also shift the current ecosystem from an arid to a hyper-arid ecosystem. Therefore, we concluded that irrigation is a practical option to support the ∆SM during the low-temperature months only (spring and winter) since the results did not show any progress during the summer season. It is also essential to consider the possibility of future shifting in ecosystems and plant communities in restoration and revegetation planning.
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Sun, Yihan, Guang Zhao, Zhoutao Zheng, Yixuan Zhu, Juntao Zhu, Yangping Di, Jie Gao, Mengke Cai e Yangjian Zhang. "Wetting-warming climate increases ecosystem carbon use efficiency of Chinese arid and semi-arid ecosystem". Agricultural and Forest Meteorology 351 (maggio 2024): 110018. http://dx.doi.org/10.1016/j.agrformet.2024.110018.
Testo completo
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Fan, Xin, Haoran Yu, Damien Sinonmatohou Tiando, Yuejing Rong, Wenxu Luo, Chan Eme, Shengya Ou, Jiangfeng Li e Zhe Liang. "Impacts of Human Activities on Ecosystem Service Value in Arid and Semi-Arid Ecological Regions of China". International Journal of Environmental Research and Public Health 18, n. 21 (22 ottobre 2021): 11121. http://dx.doi.org/10.3390/ijerph182111121.
Testo completoAbstract (sommario):
The quantitative and spatial–temporal variations in the characteristics of ecosystem value can be helpful to improve environmental protection and climate adaptation measures and adjust the balance between economic development and the ecological environment. The arid and semi-arid regions of China are undergoing the effects of climate change across the entire northern hemisphere. Their ecological environments are fragile and in conflict with anthropogenic activities, which significantly altered more ecosystems services in these regions. Therefore, estimating the effects of anthropogenic activities on ecosystem services is important for formulating ecological policy and regional environmental mitigation plans of these regions. This study employed the model of ecosystem service value (ESV) assessment and the bivariate spatial autocorrelation method to reveal the spatiotemporal variations in the characteristics of ecosystem value in the arid and semi-arid ecological regions of China and its interaction with human activities. Results showed that (1) the total value of ES of the study area increased from USD 487,807 billion in 2000 to USD 67,831,150 billion 2020; (2) the ES value provided by forest land first increased by 5.60% from 2000 to 2020; (3) the ESV provided by grassland showed an overall decline over the 20 years. Food and raw material production showed the lowest ES value, and climate regulation and soil conservation decreased from 2000 to 2020; (4) the index of human footprint patches decreased from 45.80% in 2000 to 17.63% in 2020, while the high and very high human footprint index areas increased significantly, mainly due to the rapid urbanization and improvement of railway networks in these areas. Spatially, the regions with high human footprint were mostly dispersed in the northeastern of China such as Shanxi and Gansu, whereas the regions with a low human footprint remained mainly located in the central and southwestern parts of China; (5) significant spatial dependencies between changes in ESV and the human footprint index were recorded. Our study could provide a scientific basis for ecosystem functions regulation and land development security in arid and semi-arid ecological regions.
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Luković, Milica, e Urban Šilc. "Management of continental saline ecosystems in the Republic of Serbia: Are these ecosystems suitable for nature-based tourism?" Menadzment u hotelijerstvu i turizmu 9, n. 2 (2021): 37–49. http://dx.doi.org/10.5937/menhottur2102037l.
Testo completoAbstract (sommario):
Continental saline habitats represent unique, authentic and rare ecosystems. These ecosystems are typically distributed in arid and semi-arid regions; however, they are also found in inland areas in temperate climate zones. Usually, the general public is not familiar with this particular type of ecosystem. In order to present saline habitats to tourists, a broadly applied method of ecosystem suitability assessment (ESI-ecosystem suitability index) was used and adjusted to the purposes of this research. The research aims to estimate the nature-based tourism potentials of selected sites. Thus, six representative halophytic habitats distributed along the geographic gradient, from the Pannonian Plain to the south of Serbia, were chosen. In terms of each site, seven indicators (e.g., flora and vegetation, bird fauna, landscape, protection status, accessibility, and ecotourism facilities), important for nature-based tourism, were analyzed. The results show that the Pannonian saline habitats have greater opportunities for development of this type of tourism in almost all categories compared to southern sites.
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Zou, Jie, Jianli Ding, Shuai Huang e Bohua Liu. "Ecosystem Resistance and Resilience after Dry and Wet Events across Central Asia Based on Remote Sensing Data". Remote Sensing 15, n. 12 (18 giugno 2023): 3165. http://dx.doi.org/10.3390/rs15123165.
Testo completoAbstract (sommario):
Climate change forecasts indicate that the frequency and intensity of extreme climate events will increase in the future; these changes will have important effects on ecosystem stability and function. An important arid region of the world, Central Asia has ecosystems that are extremely vulnerable to extreme weather events. However, few studies have investigated the resistance and resilience of this region’s ecosystems to extreme weather events. In this study, first, the extreme drought/wet threshold was calculated based on the 113-year (1901–2013) standardized precipitation–evapotranspiration index (SPEI); second, moderate resolution imaging spectroradiometer (MODIS) remote sensing data were applied to calculate ecosystem water use efficiency (WUE) and quantify ecosystem resistance and resilience after different extreme climate events; and finally, differences in the changes of various ecosystem types before and after climate events were assessed. The results showed the following: (1) The average SPEI was 0.073, and the thresholds of extreme wetness and drought were 0.91 and −0.67, respectively. Central Asia experienced extreme wet periods in 2002 and 2003 and a drought period in 2008. (2) Suitable wetness levels can increase the resistance of an ecosystem; however, continuous wetness reduces ecosystem resistance, as does drought. Wet areas had strong resilience after wet events, and arid areas had strong resilience after drought events. (3) During both wet and drought years, the transition between shrubland and grassland caused changes in ecosystem resistance and resilience. These findings are important for understanding the impact of future climate change on ecosystem stability.
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Maestre, Fernando T., Matthew A. Bowker, Cristina Escolar, María D. Puche, Santiago Soliveres, Sara Maltez-Mouro, Pablo García-Palacios, Andrea P. Castillo-Monroy, Isabel Martínez e Adrián Escudero. "Do biotic interactions modulate ecosystem functioning along stress gradients? Insights from semi-arid plant and biological soil crust communities". Philosophical Transactions of the Royal Society B: Biological Sciences 365, n. 1549 (12 luglio 2010): 2057–70. http://dx.doi.org/10.1098/rstb.2010.0016.
Testo completoAbstract (sommario):
Climate change will exacerbate the degree of abiotic stress experienced by semi-arid ecosystems. While abiotic stress profoundly affects biotic interactions, their potential role as modulators of ecosystem responses to climate change is largely unknown. Using plants and biological soil crusts, we tested the relative importance of facilitative–competitive interactions and other community attributes (cover, species richness and species evenness) as drivers of ecosystem functioning along stress gradients in semi-arid Mediterranean ecosystems. Biotic interactions shifted from facilitation to competition along stress gradients driven by water availability and temperature. These changes were, however, dependent on the spatial scale and the community considered. We found little evidence to suggest that biotic interactions are a major direct influence upon indicators of ecosystem functioning (soil respiration, organic carbon, water-holding capacity, compaction and the activity of enzymes related to the carbon, nitrogen and phosphorus cycles) along stress gradients. However, attributes such as cover and species richness showed a direct effect on ecosystem functioning. Our results do not agree with predictions emphasizing that the importance of plant–plant interactions will be increased under climate change in dry environments, and indicate that reductions in the cover of plant and biological soil crust communities will negatively impact ecosystems under future climatic conditions.
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Zhu, Tianyu, Chengzhi Li, Xiaocao Liu e Xiaobing Zhao. "Assessing Ecological Restoration in Arid Mining Regions: A Progressive Evaluation System". Sustainability 16, n. 6 (8 marzo 2024): 2266. http://dx.doi.org/10.3390/su16062266.
Testo completoAbstract (sommario):
The mining activities in arid regions have resulted in significant ecological environmental issues, exacerbating the already challenging ecological conditions and leading to severe ecosystem damage. Merely relying on natural recovery processes proves inadequate, thus necessitating the implementation of artificial restoration measures to facilitate ecosystem recovery in these arid mining regions. However, it is difficult to scientifically answer the questions of how artificial restoration can be effectively combined with natural recovery, and to what extent can artificial assistance can define the beginning of natural recovery in ecosystems. To address this issue, this study proposed a stepwise ecological restoration model for arid mining regions. The model delineated the ecological restoration process in arid mining regions into three phases: “artificial reconstruction”, “auxiliary ecological restoration”, and “natural recovery”, and constructed an evaluation index system of the stepwise ecological restoration process. Taking an example of a mining ecological restoration in Aksu, Xinjiang, this study examined the evaluation effects of the stepwise ecological restoration model on ecological restoration projects in arid mining regions. The research showed that adopting the stepwise ecological restoration model in arid mining regions can achieve scientific and moderate artificial restoration, better clarify ecological restoration goals, and facilitate the implementation of ecological restoration projects.
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Xu, Lili, Tianyu Chen, Baolin Li, Yecheng Yuan e Nandin-Erdene Tsendbazar. "Spatiotemporal Evolution of Arid Ecosystems Using Thematic Land Cover Products". Remote Sensing 15, n. 12 (19 giugno 2023): 3178. http://dx.doi.org/10.3390/rs15123178.
Testo completoAbstract (sommario):
The pathway, direction, and potential drivers of the evolution in global arid ecosystems are of importance for maintaining the stability and sustainability of the global ecosystem. Based on the Climate Change Initiative Land Cover dataset (CCILC), in this study, four indicators of land cover change (LCC) were calculated, i.e., regional change intensity (RCI), rate of change in land cover (CR), evolutionary direction index (EDI), and artificial change percentage (ACP), to progressively derive the intensity, rate, evolutionary direction, and anthropogenic interferences of global arid ecosystems. The LCC from 1992 to 2020 and from 28 consecutive pair-years was observed at the global, continental, and country scales to examine spatiotemporal evolution in the Earth’s arid ecosystems. The following main results were obtained: (1) Global arid ecosystems experienced positive evolution despite complex LCCs and anthropogenic interferences. Cautious steps to avoid potential issues caused by rapid urbanization and farmland expansion are necessary. (2) The arid ecosystems in Australia, Central Asia, and southeastern Africa generally improved, as indicated by EDI values, but those in North America were degraded, with 41.1% of LCCs associated with urbanization or farming. The arid ecosystems in South America also deteriorated, but 83.4% of LCCs were in natural land covers. The arid ecosystems in Europe slightly improved with overall equivalent changes in natural and artificial land covers. (3) Global arid ecosystems experienced three phases of change based on RCI values: ‘intense’ (1992–1998), ‘stable’ (1998–2014), and ‘intense’ (2014–2020). In addition, two phases of evolution based on EDI values were observed: ‘deterioration’ (1992–2002) and ‘improvement’ (2002–2020). The ACP values indicated that urbanization and farming activities contributed increasingly less to global dryland change since 1992. These findings provide critical insights into the evolution of global arid ecosystems based on analyses of LCCs and will be beneficial for sustainable development of arid ecosystems worldwide within the context of ongoing climate change.
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Santana, Otacilio Antunes, José Imaña Encinas, Bárbara Alves de Sousa, Sandra Razana Silva do Monte e Valéria Sandra de Oliveira Costa. "Aridy index over time in five ecosystems on semiarid". Journal of Hyperspectral Remote Sensing 9, n. 3 (11 dicembre 2019): 138. http://dx.doi.org/10.29150/jhrs.v9.3.p138-145.
Testo completoAbstract (sommario):
The local climate change was registered over time (1992-2018) on different land use ecosystems, in Brazilian Semiarid area. The aimed of this work was to analyze aridity index in five ecosystems (Wild Caatinga, Caatinga on management, Cactaceae field, Eucalyptus reforestation, and Fabaceae crop), and to compare this index with environment variables. Meteorological towers and measures with porometer and psychrometers were carried out to collect the data. The main result was that the studied areas are hotter and drier. The Fabaceae crop and Eucalyptus reforestation studied ecosystems already are on Arid classification according with registered aridity index. Wild Caatinga and Cactaceae field ecosystems are on Semiarid classification, and over time Caatinga on management ecosystem pass from Semiarid to Arid classification. The five ecosystems together are classified on Arid climate. The VPD and Ψsoil were the variables more directly proportional with Aridity index to analyzed ecosystems.
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Gu, Qing, Hui Zheng, Li Yao, Min Wang, Mingguo Ma, Xufeng Wang e Xuguang Tang. "Performance of the Remotely-Derived Products in Monitoring Gross Primary Production across Arid and Semi-Arid Ecosystems in Northwest China". Land 9, n. 9 (22 agosto 2020): 288. http://dx.doi.org/10.3390/land9090288.
Testo completoAbstract (sommario):
As an important component to quantify the carbon budget, accurate evaluation of terrestrial gross primary production (GPP) is crucial for large-scale applications, especially in dryland ecosystems. Based on the in situ data from six flux sites in northwestern China from 2014 to 2016, this study compares seasonal and interannual dynamics of carbon fluxes between these arid and semi-arid ecosystems and the atmosphere. Meanwhile, the reliability of multiple remotely-derived GPP products in representative drylands was examined, including the Breathing Earth System Simulator (BESS), the Moderate Resolution Imaging Spectroradiometer (MODIS) and data derived from the OCO-2 solar-induced chlorophyll fluorescence (GOSIF). The results indicated that the carbon fluxes had clear seasonal patterns, with all ecosystems functioning as carbon sinks. The maize cropland had the highest GPP with 1183 g C m−2 y−1. Although the net ecosystem carbon exchange (NEE) in the Tamarix spp. ecosystem was the smallest among these flux sites, it reached 208 g C m−2 y−1. Furthermore, distinct advantages of GOSIF GPP (with R2 = 0.85–0.98, and RMSE = 0.87–2.66 g C m−2 d−1) were found with good performance. However, large underestimations in three GPP products existed during the growing seasons, except in grassland ecosystems. The main reasons can be ascribed to the uncertainties in the key model parameters, including the underestimated light use efficiency of the MODIS GPP, the same coarse land cover product for the BESS and MODIS GPP, the coarse gridded meteorological data, and distribution of C3 and C4 plants. Therefore, it still requires more work to accurately quantify the GPP across these dryland ecosystems.
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Shi, Ming, Fei Lin, Xia Jing, Bingyu Li, Yang Shi e Yimin Hu. "Ecological Environment Quality Assessment of Arid Areas Based on Improved Remote Sensing Ecological Index—A Case Study of the Loess Plateau". Sustainability 15, n. 18 (18 settembre 2023): 13881. http://dx.doi.org/10.3390/su151813881.
Testo completoAbstract (sommario):
Ecosystems in arid and semi-arid areas are delicate and prone to different erosive effects. Monitoring and evaluating the environmental ecological condition in such areas contribute to the governance and restoration of the ecosystem. Remote sensing ecological indices (RSEIs) are widely used as a method for environmental monitoring and have been extensively applied in various regions. This study selects the arid and semi-arid Loess Plateau as the research area, in response to existing research on ecological monitoring that predominantly uses vegetation indices as monitoring indicators for greenness factors. A fluorescence remote sensing ecological index (SRSEI) is constructed by using monthly synthesized sun-induced chlorophyll fluorescence data during the vegetation growth period as a new component for greenness and combining it with MODIS product data. The study generates the RSEI and SRSEI for the research area spanning from 2001 to 2021. The study compares and analyzes the differences between the two indices and explores the evolution patterns of the ecosystem quality in the Loess Plateau over a 21-year period. The results indicate consistent and positively correlated linear fitting trend changes in the RSEI and SRSEI for the research area between 2001 and 2021. The newly constructed ecological index exhibits a higher correlation with rainfall data, and it shows a more significant decrease in magnitude during drought occurrences, indicating a faster and stronger response of the new index to drought in the research area. The largest proportions are found in the research area’s regions with both substantial and minor improvements, pointing to an upward tendency in the Loess Plateau’s ecosystem development. The newly constructed environmental index can effectively evaluate the quality of the ecosystem in the research area.
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Chen, Ying Ying, Huan Yang, Gen Sheng Bao, Xiao Pan Pang e Zheng Gang Guo. "Effect of the presence of plateau pikas on the ecosystem services of alpine meadows". Biogeosciences 19, n. 18 (19 settembre 2022): 4521–32. http://dx.doi.org/10.5194/bg-19-4521-2022.
Testo completoAbstract (sommario):
Abstract. The activity of small mammalian herbivores influences grassland ecosystem services in arid and semi-arid regions. Plateau pika (Ochotona curzoniae) was considered to be a focal organism to investigate the effect of small mammalian herbivores on meadow ecosystem services in alpine regions. In this study, a home-range scale was used to measure the forage available to livestock, water conservation, carbon sequestration and soil nutrient maintenance (total nitrogen, phosphorus and potassium) in the topsoil layer, and a quadrat scale was used to assess the biodiversity conservation of alpine meadows. This study showed that the forage available to livestock and water conservation was 19 % and 16 % lower in the presence of plateau pikas than in their absence, and biodiversity conservation, carbon sequestration, soil nitrogen and phosphorus maintenance was 15 %, 29 %, 10 % and 8.9 % higher in the presence of plateau pikas than in their absence. In contrast, it had no impact on soil potassium maintenance of meadow ecosystems in alpine regions. The forage available to livestock, biodiversity conservation and soil nutrient maintenance of meadow ecosystems in alpine regions had maximum values as the disturbance intensity of plateau pikas increased; the water conservation tended to decrease linearly with the increasing disturbance intensity of plateau pikas. These results present a pattern of plateau pikas influencing the ecosystem services of meadow ecosystems in alpine regions, enriching our understanding of the small mammalian herbivores in relation to grassland ecosystem service.
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Azizah, Isnaniar Rahmatul, Rahmatia Harahap, Betty Natalie Fitriatin, Nadia N. Kamaluddin e Tualar Simarmata. "ABUNDANCE OF N2-FIXING RHIZOBACTERIA OF DIFFERENT DRYLAND AGRICULTURE ECOSYSTEMS IN DRY CLIMATE ZONE OF LOMBOK-INDONESIA". International Journal of Agriculture, Environment and Bioresearch 07, n. 05 (2022): 24–35. http://dx.doi.org/10.35410/ijaeb.2022.5761.
Testo completoAbstract (sommario):
Soil microbial communities are crucial in ecosystem diversity and are directly related to soil fertility. Lombok is an island in central Indonesia that has low soil fertility and a limited amount of available water. Beneficial microorganisms can be used as a low-cost and environmental friendly tool to increase productivity in dryland agriculture systems. Screening to obtain superior rhizosphere bacteria is one of the options to support the nutrient supply in arid soils. Composites soil samples were taken from five ecosystems in Lombok, West Nusa Tenggara, an arid region in the eastern part of Indonesia to obtain the isolates of nitrogen-fixer rhizobacteria (NFR). Nine Azotobacter and Azopirillium spp were isolated from, rainfed, maize, mixed crop, natural forests, and savanna ecosystems. Abundance of total bacteria and N2-fixers in all ecosystems was relatively high (more than 108 cfu g-1), and the highest total population was recorded in the natural forest. The abundance of N2-fixer rhizobacteria recorded the highest Azotobacter population at 2.64 x 108 cfu g-1 in the maize ecosystem and the highest Azospirillum population at 2.32 x 108 cfu g-1 in the natural forest ecosystem. Additionally, the highest contain of organic C and total nitrogen were obtained in natural forest and savanna ecosystem. Eighteen isolates were obtained and characterized microscopic and macroscopically, consisted of nine Azotobacter sp and nine Azospirillium isolates which are potentially to be used as biogent for improving the growth of upland rice on dry climate zone.
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Li, Shuaishuai, Jiahua Zhang, Sha Zhang, Yun Bai, Dan Cao, Tiantian Cheng, Zhongtai Sun, Qi Liu e Til Prasad Pangali Sharma. "Impacts of Future Climate Changes on Spatio-Temporal Distribution of Terrestrial Ecosystems over China". Sustainability 13, n. 6 (10 marzo 2021): 3049. http://dx.doi.org/10.3390/su13063049.
Testo completoAbstract (sommario):
Understanding the response of terrestrial ecosystems to future climate changes would substantially contribute to the scientific assessment of vegetation–climate interactions. Here, the spatiotemporal distribution and dynamics of vegetation in China were projected and compared based on comprehensive sequential classification system (CSCS) model under representative concentration pathway (RCP) RCP2.6, RCP4.5, and RCP8.5 scenarios, and five sensitivity levels were proposed. The results show that the CSCS model performs well in simulating vegetation distribution. The number of vegetation types would increase from 36 to 40. Frigid–perhumid rain tundra and alpine meadow are the most distributed vegetation types, with an area of more than 78.45 × 104 km2, whereas there are no climate conditions suitable for tropical–extra-arid tropical desert in China. Some plants would benefit from climate changes to a certain extent. Warm temperate–arid warm temperate zone semidesert would expand by more than 1.82% by the 2080s. A continuous expansion of more than 18.81 × 104 km2 and northward shift of more than 124.93 km in tropical forest would occur across all three scenarios. However, some ecosystems would experience inevitable changes. More than 1.33% of cool temperate–extra-arid temperate zone desert would continuously shrink. Five sensitivity levels present an interphase distribution. More extreme scenarios would result in wider ecosystem responses. The evolutionary trend from cold–arid vegetation to warm–wet vegetation is a prominent feature despite the variability in ecosystem responses to climate changes.
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Wei, Maohong, Hailing Li, Muhammad Adnan Akram, Longwei Dong, Ying Sun, Weigang Hu, Haiyang Gong et al. "Quantifying Drought Resistance of Drylands in Northern China from 1982 to 2015: Regional Disparity in Drought Resistance". Forests 13, n. 1 (11 gennaio 2022): 100. http://dx.doi.org/10.3390/f13010100.
Testo completoAbstract (sommario):
Drylands are expected to be affected by greater global drought variability in the future; consequently, how dryland ecosystems respond to drought events needs urgent attention. In this study, the Normalized Vegetation Index (NDVI) and Standardized Precipitation and Evaporation Index (SPEI) were employed to quantify the resistance of ecosystem productivity to drought events in drylands of northern China between 1982 and 2015. The relationships and temporal trends of resistance and drought characteristics, which included length, severity, and interval, were examined. The temporal trends of resistance responded greatest to those of drought length, and drought length was the most sensitive and had the strongest negative effect with respect to resistance. Resistance decreased with increasing drought length and did not recover with decreasing drought length in hyper-arid regions after 2004, but did recover in arid and semi-arid regions from 2004 and in dry sub-humid regions from 1997. We reason that the regional differences in resistance may result from the seed bank and compensatory effects of plant species under drought events. In particular, this study implies that the ecosystem productivity of hyper-arid regions is the most vulnerable to drought events, and the drought–resistance and drought–recovery interactions are likely to respond abnormally or even shift under ongoing drought change.
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Kulik, K. N., e A. N. Salugin. "Arid ecosystem dynamics and self-pulse processes". Russian Agricultural Sciences 41, n. 2-3 (giugno 2015): 183–86. http://dx.doi.org/10.3103/s1068367415020135.
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Marsh, Paul C., e Stuart G. Fisher. "Metabolism of an arid region canal ecosystem". Journal of Arid Environments 12, n. 3 (maggio 1987): 255–67. http://dx.doi.org/10.1016/s0140-1963(18)31170-4.
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Frank, Douglas A., e Peter M. Groffman. "Denitrification in a semi-arid grazing ecosystem". Oecologia 117, n. 4 (22 dicembre 1998): 564–69. http://dx.doi.org/10.1007/s004420050693.
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Hou, Zhufeng, Guanghui Lv e Lamei Jiang. "Functional Diversity Can Predict Ecosystem Functions Better Than Dominant Species: The Case of Desert Plants in the Ebinur Lake Basin". Sustainability 13, n. 5 (6 marzo 2021): 2858. http://dx.doi.org/10.3390/su13052858.
Testo completoAbstract (sommario):
Studying the impact of biodiversity on ecosystem multifunctionality is helpful for clarifying the ecological mechanisms (such as niche complementary effects and selection) of ecosystems providing multiple services. Biodiversity has a significant impact on ecosystem versatility, but the relative importance of functional diversity and dominant species to ecosystem functions needs further evaluation. We studied the desert plant community in Ebinur Lake Basin. Based on field survey data and experimental analysis, the relationship between the richness and functional diversity of dominant species and the single function of ecosystem was analyzed. The relative importance of niche complementary effect and selective effect in explaining the function of plant diversity in arid areas is discussed. There was no significant correlation between desert ecosystem functions (soil available phosphorus, organic matter, nitrate nitrogen, and ammonium nitrogen) and the richness of the dominant species Nitraria tangutorum (p < 0.05). Soil organic matter and available phosphorus had significant effects on specific leaf area and plant height (p < 0.05). Functional dispersion (FDis) had a significant effect on soil available phosphorus, while dominant species dominant species richness (SR) had no obvious effect on single ecosystem function. A structural equation model showed that dominant species had no direct effect on plant functional diversity and ecosystem function, but functional diversity had a strong direct effect on ecosystem function, and its direct coefficients of action were 0.226 and 0.422. The results can help to explain the response mechanism of multifunctionality to biodiversity in arid areas, which may provide referential significance for vegetation protection and restoration for other similar areas.
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García-Llorente, Marina, Antonio J. Castro, Cristina Quintas-Soriano, Elisa Oteros-Rozas, Irene Iniesta-Arandia, José González, David García del Amo et al. "Local Perceptions of Ecosystem Services Across Multiple Ecosystem Types in Spain". Land 9, n. 9 (18 settembre 2020): 330. http://dx.doi.org/10.3390/land9090330.
Testo completoAbstract (sommario):
Combining socio-cultural valuations of ecosystem services with ecological and monetary assessments is critical to informing decision making with an integrative and multi-pronged approach. This study examined differences in the perceptions of ecosystem service supply and diversity across eight major ecosystem types in Spain and scrutinized the social and ecological factors shaping these perceptions. First, we implemented 1932 face-to-face questionnaires among local inhabitants to assess perceptions of ecosystem service supply. Second, we created an ecosystem service diversity index to measure the perceived diversity of services considering agroecosystems, Mediterranean mountains, arid systems, two aquatic continental systems, coastal ecosystems and two urban ecosystems. Finally, we examined the influence of biophysical, socio-demographic and institutional factors in shaping ecosystem service perceptions. Overall, cultural services were the most widely perceived, followed by provisioning and regulating services. Provisioning services were most strongly associated with agroecosystems, mountains and coastal systems, whereas cultural services were associated with urban ecosystems and regulating services were specifically linked with agroecosystems, mountains and urban recreational areas. The highest service diversity index values corresponded to agroecosystems, mountains and wetlands. Our results also showed that socio-demographic factors, such as place of origin (urban vs. rural) and educational level, as well as institutional factors, such as management and access regimes, shaped the perception of ecosystem services.
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Atazadeh, Ehsan, Andrew Barton, Mozhgan Shirinpour, Mahdi Zarghami e Abbas Rajabifard. "River management and environmental water allocation in regulated ecosystems of arid and semi-arid regions – A review". Fundamental and Applied Limnology / Archiv für Hydrobiologie 193, n. 4 (23 giugno 2020): 327–45. http://dx.doi.org/10.1127/fal/2020/1286.
Testo completoAbstract (sommario):
Rivers make a significant contribution in providing goods and services for human well-being. Today, many rivers and streams have been heavily regulated to ensure adequate provision of water resources for anthropogenic uses. Riverine ecosystems, especially those in arid and semi-arid regions, are experiencing severe stress due to the increasing demands on the ecosystem services they provide, coupled with anthropogenic catchment-scale impacts and factors associated with natural and human-induced climate variability and change. In this paper, the various flow components in regulated riverine ecosystems and the methods to determine environmental flows are reviewed. The review also focuses on the concurrent developments of eco-hydrological models and on the new opportunities for improving environmental flows of rivers by sustainably adjusting consumptive flows to fine-tune environmental flows and maximize the ecological benefit. In fact, the present paper highlights the role of consumptive flows, towards improving environmental flows, which has largely been neglected by river scientists and water managers. Indeed, consumptive flows can provide an opportunity to improve and support environmental flows in regulated riverine ecosystems. Addressing these challenges may aid water management efforts in finding sustainable solutions in riverine ecosystems by balancing environmental/ecological and human water requirements.
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Feng, Siyuan, Xin Liu, Wenwu Zhao, Ying Yao, Ao Zhou, Xiaoxing Liu e Paulo Pereira. "Key Areas of Ecological Restoration in Inner Mongolia Based on Ecosystem Vulnerability and Ecosystem Service". Remote Sensing 14, n. 12 (7 giugno 2022): 2729. http://dx.doi.org/10.3390/rs14122729.
Testo completoAbstract (sommario):
Inner Mongolia is located in China’s arid and semi-arid regions, with sensitive and fragile ecosystems at risk of increased desertification, necessitating ecological restoration. However, economic resources for large-scale ecological restoration are often scarce, so it is vital to identify key areas for ecological restoration. Previous desertification research has focused mainly on the condition and changes in soil or vegetation. However, not all changes in soil or vegetation directly impact humans. New perspectives are increasingly needed to bridge the gap between biophysical and human well-being. We construct a framework to identify priority restoration areas based on ecosystem services and ecosystem vulnerability over a long time series. The results show that: (1) soil conservation services in northeast and southwest Inner Mongolia have degraded. Sand fixation services in central and eastern Inner Mongolia have shown a degradation trend. Habitat quality has been generally stable and sporadic in the past 20 years. (2) The areas with higher ecosystem vulnerability are concentrated in the northeast, mainly due to higher climate exposure and climate sensitivity but relatively lower climate resilience in the northeast. (3) Compared with the results of ecological restoration areas identified based on the trends of traditional vegetation indicators (fractional vegetation cover and net primary productivity), we found a greater proportion of land in northeastern Inner Mongolia in need of restoration. Additionally, there was identified a decreased restoration proportion in southwestern Inner Mongolia to ensure the self-restoration and regulation of desert ecosystems, which is conducive to realizing nature-based solutions.
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Wu, Dan, Wei Wei, Zongshan Li e Qindi Zhang. "Coupling Effects of Terracing and Vegetation on Soil Ecosystem Multifunctionality in the Loess Plateau, China". Sustainability 15, n. 2 (16 gennaio 2023): 1682. http://dx.doi.org/10.3390/su15021682.
Testo completoAbstract (sommario):
In semi-arid and arid terrestrial ecosystems, terracing and vegetation may improve soil conditions and enhance habitats. Considerable recent works have focused on evaluating how terracing and vegetation affect individual ecosystem function, but none of these evaluations included soil ecosystem multifunctionality (SEMF), which has a positive significance for optimizing soil ecosystem management. Based on the survey data of six different combinations of terracing and vegetation in the Chinese Loess Plateau, 15 functional indicators related to soil fertility, nutrient transformation/cycling, and water conservation were selected. The maximum conversion of the mean value method was employed to quantify SEMF. Concerning individual ecosystem services, the capacities of half-moon terraces-Pinus tabulaeformis (Ht-P. tabulaeformis) and level benches-Caragana korshinskii (Lb-C. korshinskii) to maintain soil fertility were 43.25% and 42.01% higher than those of counter-slope terraces-Platycladus orientalis (Ct-P. orientalis). On the contrary, Ct-P. orientalis showed better nutrient transformation and cycling services, which was 9.23% higher than those of Ht-P. tabulaeformis, therefore, we observed the highest SEMF in the Ht-P. tabulaeformis. Terracing, with a 29.2% explained variation, had a greater influence than that of vegetation (12.6%), while the coupling effect of terracing and vegetation (37.9%) was the most important factor that determined the SEMF. Thus, Ht-P. tabulaeformis and Lb-C. korshinskii should be promoted in the Loess Plateau area. The results of this study have significance in terms of understanding the interactions between terracing, vegetation, and soil ecosystems.
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Eamus, D., S. Zolfaghar, R. Villalobos-Vega, J. Cleverly e A. Huete. "Groundwater-dependent ecosystems: recent insights, new techniques and an ecosystem-scale threshold response". Hydrology and Earth System Sciences Discussions 12, n. 5 (4 maggio 2015): 4677–754. http://dx.doi.org/10.5194/hessd-12-4677-2015.
Testo completoAbstract (sommario):
Abstract. Groundwater-dependent ecosystems (GDEs) are at risk globally due to unsustainable levels of groundwater extraction, especially in arid and semi-arid regions. In this review, we examine recent developments in the ecohydrology of GDEs with a focus on three knowledge gaps: (1) how do we locate GDEs, (2) how much water is transpired from shallow aquifers by GDEs; and (3) what are the responses of GDEs to excessive groundwater extraction? The answers to these questions will determine water allocations that are required to sustain functioning of GDEs and to guide regulations on groundwater extraction to avoid negative impacts on GDEs. We discuss three methods for identifying GDEs: (1) fluctuations in depth-to-groundwater that are associated with diurnal variations in transpiration, (2) stable isotope analysis of water sources in the transpiration stream; and (3) remote sensing methods. We then discuss several methods for estimating rates of GW use, including direct measurement using sapflux or eddy covariance technologies, estimation of a climate wetness index within a Budyko framework, spatial distribution of ET using remote sensing, groundwater modelling and stable isotopes. Remote sensing methods often rely on direct measurements to calibrate the relationship between vegetation indices and ET. ET from GDEs is also determined using hydrologic models of varying complexity, from the "White method" to fully coupled, variable saturation models. Combinations of methods are typically employed to obtain clearer insight into the components of groundwater discharge in GDEs, such as the proportional importance of transpiration vs. evaporation (e.g., using stable isotopes) or from groundwater vs. rainwater sources. Groundwater extraction can have severe consequences on structure and function of GDEs. In the most extreme cases, phreatophytes experience crown dieback and death following groundwater drawdown. We provide a brief review of two case studies of the impacts of GW extraction and discuss the use of C isotope ratios in xylem to reveal past influences of GW extraction. We conclude with a discussion of a depth-to-groundwater threshold in mesic and semi-arid GDEs. Across this threshold, significant changes occur in ecosystem structure and function.
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LAL JAKHAR, BHANWAR, AS BALODA, MD CHOUDHARY, KK SAINI, ML JAKHAR e T. YADAV. "Biodiversity of white grub, (Coleoptera: Scaraeidae) in semi arid agro-ecosystem of Rajasthan". Journal of AgriSearch 8, n. 2 (30 giugno 2021): 112–16. http://dx.doi.org/10.21921/jas.v8i2.7293.
Testo completoAbstract (sommario):
White grubs are the major insect pests of cultivated plants in semi arid agro-ecosystem of Rajasthan. It is important to understand diversity, abundance and distribution of scarabaeid beetles for planning effective pest management programme. The experimental data were collected from nine locations in three different ecosystems in Kharif season of year 2019. Species identification revealed that there was total nine species were recorded from 18885 specimens collected. The identified species were belongs under two subfamilies of Scarabaeidae family. Maximum specimens were collected in the month of July from selected sites. When species diversity was compared among different locations, it was found that Shannon Wiener diversity index varied from 1.235 to 1.095, which indicates that species were less diverse but frequently present. The present study can be used to formulate the integrated pest management strategies based on most abundance and diverse scarabaeids in semi-arid agro-ecosystem of Rajasthan.
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Chen, Zheng, Jieyu Liu, Zhonghua Qian, Li Li, Zhiseng Zhang, Guolin Feng, Shigui Ruan e Guiquan Sun. "Monitoring Land Degradation through Vegetation Dynamics Mathematical Modeling: Case of Jornada Basin (in the U.S.)". Remote Sensing 15, n. 4 (10 febbraio 2023): 978. http://dx.doi.org/10.3390/rs15040978.
Testo completoAbstract (sommario):
Arid ecosystems are known to be sensitive to climate change. The Jornada Basin in the USA, as one representative of arid land, has suffered from land degradation in recent decades. In order to disentangle the climate–vegetation feedback, we analyzed the vegetation dynamics under the effects of climate change via a mathematical model based on the reaction–diffusion mechanism. Using this model, we conducted a sensitive analysis of climate factors and concluded that the ecosystem might experience a catastrophic shift with the climatic deterioration. We considered the non-local interaction term to explain the competition among plants. Additionally, the PLR (power law range) metric was used to quantify the extent of the degradation and to compare the results of the vegetation patterns from the remote sensing data and the simulations. From the results, this model could simulate the trends of land degradation in this area. We found that the land degradation could be mainly attributed to climate changes in recent years. This approach suggests that vegetation patterns can provide hints as to whether the ecosystem is approaching desertification. These results can help with mapping vulnerable arid areas around the world through model simulation and satellite images.
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Xu, Shiqin, e Zhongbo Yu. "Environmental Control on Transpiration: A Case Study of a Desert Ecosystem in Northwest China". Water 12, n. 4 (24 aprile 2020): 1211. http://dx.doi.org/10.3390/w12041211.
Testo completoAbstract (sommario):
Arid and semi-arid ecosystems represent a crucial but poorly understood component of the global water cycle. Taking a desert ecosystem as a case study, we measured sap flow in three dominant shrub species and concurrent environmental variables over two mean growing seasons. Commercially available gauges (Flow32 meters) based on the constant power stem heat balance (SHB) method were used. Stem-level sap flow rates were scaled up to stand level to estimate stand transpiration using the species-specific frequency distribution of stem diameter. We found that variations in stand transpiration were closely related to changes in solar radiation (Rs), air temperature (T), and vapor pressure deficit (VPD) at the hourly scale. Three factors together explained 84% and 77% variations in hourly stand transpiration in 2014 and 2015, respectively, with Rs being the primary driving force. We observed a threshold control of VPD (~2 kPa) on stand transpiration in two-year study periods, suggesting a strong stomatal regulation of transpiration under high evaporative demand conditions. Clockwise hysteresis loops between diurnal transpiration and T and VPD were observed and exhibited seasonal variations. Both the time lags and refill and release of stem water storage from nocturnal sap flow were possible causes for the hysteresis. These findings improve the understanding of environmental control on water flux of the arid and semi-arid ecosystems and have important implications for diurnal hydrology modelling.
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Liang, Siqi, Shouzhang Peng e Yunming Chen. "Carbon Cycles of Forest Ecosystems in a Typical Climate Transition Zone under Future Climate Change: A Case Study of Shaanxi Province, China". Forests 10, n. 12 (16 dicembre 2019): 1150. http://dx.doi.org/10.3390/f10121150.
Testo completoAbstract (sommario):
As global climate change has a large effect on the carbon cycle of forests, it is very important to understand how forests in climate transition regions respond to climate change. Specifically, the LPJ-GUESS (Lund-Potsdam-Jena General Ecosystem Simulator) model was used to simulate net ecosystem productivity (NEP) and soil heterotrophic respiration (Rh) dynamics of two forest ecosystems of different origins between 1951 and 2100, to quantitatively analyze the carbon source and sink functions and potential changes in soil carbon dynamics in arid and humid regions under future climate change, simulate the dynamics of forest net primary productivity (NPP) under different climatic factors, and analyze the sensitivity of forests in arid and humid regions to temperature, precipitation, and carbon dioxide (CO2) concentration. We found that: (1) in both the historical and future periods, the average NEP of both studied forests in the humid region was larger than that in the arid region, the carbon sink function of the humid region being predicted to become stronger and the arid zone possibly becoming a carbon source; (2) between 1951 and 2100, the forest soil Rh in the arid region was lower than that in the humid region and under future climate change, forest in the humid region may have higher soil carbon loss; (3) increasing temperature had a negative effect and CO2 concentration had a positive effect on the forests in the study area, and forests in arid areas are more sensitive to precipitation change. We believe our research could be applied to help policy makers in planning sustainable forest management under future climate change.
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Cheng, Kaili, Zhongmin Hu, Shenggong Li, Qun Guo, Yanbin Hao e Wenping Yuan. "Improvement of predicting ecosystem productivity by modifying carbon–water–nitrogen coupling processes in a temperate grassland". Journal of Plant Ecology 14, n. 1 (9 novembre 2020): 10–21. http://dx.doi.org/10.1093/jpe/rtaa072.
Testo completoAbstract (sommario):
Abstract Aims Prediction of changes in ecosystem gross primary productivity (GPP) in response to climatic variability is a core mission in the field of global change ecology. However, it remains a big challenge for the model community to reproduce the interannual variation (IAV) of GPP in arid ecosystems. Accurate estimates of soil water content (SWC) and GPP sensitivity to SWC are the two most critical aspects for predicting the IAV of GPP in arid ecosystems. Methods We took a widely used model Biome-BGC as an example, to improve the model performances in a temperate grassland ecosystem. Firstly, we updated the estimation of SWC by modifying modules of evapotranspiration, SWC vertical profile and field capacity. Secondly, we modified the function of controlling water–nitrogen relation, which regulates the GPP–SWC sensitivity. Important Findings The original Biome-BGC overestimated the SWC and underestimated the IAV of GPP sensitivity, resulting in lower IAV of GPP than the observations, e.g. it largely underestimated the reduction of GPP in drought years. In comparison, the modified model accurately reproduced the observed seasonal and IAVs in SWC, especially in the surface layer. Simulated GPP–SWC sensitivity was also enhanced and became closer to the observations by optimizing parameter controlling nitrogen mineralization. Consequently, the model’s capability of reproducing IAV of GPP has been largely improved by the modifications. Our results demonstrate that SWC in the surface layer and the consequent effects on nitrogen availability should be among the first considerations for accurate modeling IAV of GPP in arid ecosystems.
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El-Madany, Tarek S., Arnaud Carrara, M. Pilar Martín, Gerardo Moreno, Olaf Kolle, Javier Pacheco-Labrador, Ulrich Weber, Thomas Wutzler, Markus Reichstein e Mirco Migliavacca. "Drought and heatwave impacts on semi-arid ecosystems' carbon fluxes along a precipitation gradient". Philosophical Transactions of the Royal Society B: Biological Sciences 375, n. 1810 (7 settembre 2020): 20190519. http://dx.doi.org/10.1098/rstb.2019.0519.
Testo completoAbstract (sommario):
The inter-annual variability (IAV) of the terrestrial carbon cycle is tightly linked to the variability of semi-arid ecosystems. Thus, it is of utmost importance to understand what the main meteorological drivers for the IAV of such ecosystems are, and how they respond to extreme events such as droughts and heatwaves. To shed light onto these questions, we analyse the IAV of carbon fluxes, its relation with meteorological variables, and the impact of compound drought and heatwave on the carbon cycle of two similar ecosystems, along a precipitation gradient. A four-year long dataset from 2016 to 2019 was used for the FLUXNET sites ES-LMa and ES-Abr, located in central (39°56'25″ N 5°46'28″ W) and southeastern (38°42'6″ N 6°47'9″ W) Spain. We analyse the physiological impact of compound drought and heatwave on the dominant tree species, Quercus ilex. Our results show that the gross primary productivity of the wetter ecosystem was less sensitive to changes in soil water content, compared to the dryer site. Still, the wetter ecosystem was a source of CO 2 each year, owing to large ecosystem respiration during summer; while the dry site turned into a CO 2 sink during wet years. Overall, the impact of the summertime compound event on annual CO 2 fluxes was marginal at both sites, compared to drought events during spring or autumn. This highlights that drought timing is crucial to determine the annual carbon fluxes in these semi-arid ecosystems. This article is part of the theme issue ‘Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale’.
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Khosravi Mashizi, Azam, e Mohsen Sharafatmandrad. "Assessing the effects of shrubs on ecosystem functions in arid sand dune ecosystems". Arid Land Research and Management 34, n. 2 (2 luglio 2019): 171–87. http://dx.doi.org/10.1080/15324982.2019.1634655.
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Zhu, Ping, Wei Cao, Lin Huang, Tong Xiao e Jun Zhai. "The Impacts of Human Activities on Ecosystems within China’s Nature Reserves". Sustainability 11, n. 23 (23 novembre 2019): 6629. http://dx.doi.org/10.3390/su11236629.
Testo completoAbstract (sommario):
Protected areas (PAs) provide refuges for threatened species and are considered to be the most important approach to biodiversity conservation. Besides climate change, increasing human population is the biggest threat to biodiversity and habitats in PAs. In this paper, the temporal and spatial variations of land cover changes (LCC), vegetation fraction (VFC), and net primary productivity (NPP) were studied to present the ecosystem dynamics of habitats in 6 different types of national nature reserves (NNRs) in 8 climate zones in China. Furthermore, we used Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) nighttime light datasets and the human disturbance (HD) index estimated from LCC to quantify the living and developing human pressures within the NNRs in the period 2000–2013. The results showed that (1) the living human activities of NNRs increased apparently in the humid warm-temperate zone, Qinghai-Tibet Plateau, mid-temperate semi-arid zone, and mid-temperate humid zone, with the highest increase of nighttime light observed in inland wetlands; (2) the developing human activities in NNRs indicated by the HD index were higher in the humid warm-temperate zone and mid-temperate semi-arid zone as a result of increasing areas of agricultural and built activities, and lower in the sub-tropics due to improved conservation of forest ecosystems; (3) the relationship between HD and VFC suggests that ecosystems in most NNRs of south-subtropics, mid-temperate arid zone and Qinghai-Tibet Plateau were predominantly impacted by climate change. However, HDs were the prevalent factor of ecosystem dynamics in most NNRs of north-subtropics, mid-temperate semi-arid and humid zones.
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Hou, Jian, Menghan Wu e Haobo Feng. "Applying Trait-Based Modeling to Achieve Functional Targets during the Ecological Restoration of an Arid Mine Area". Agronomy 12, n. 11 (13 novembre 2022): 2833. http://dx.doi.org/10.3390/agronomy12112833.
Testo completoAbstract (sommario):
(1) Background: Because ecosystem degradation has become a global phenomenon which seriously affects the health of natural ecosystems and human well-being, restoration of degraded ecosystems has attracted increasing attention. However, many of the methods used in current ecological restoration work have rarely combined ecological restoration practices with the quantitative goal of restoring ecosystem function. (2) Methods: In this study, based on the conceptual framework of response-effect traits and Community Assembly by Trait Selection model (CATS model), a restoration strategy for a degraded abandoned mine in Wuhai City, China has been provided. This restoration strategy connected the ecosystem function targets to the appropriate recovery species and their required abundances. (3) Results: The results showed that a relative abundance ratio of 8:2 for S. grandis to B. dasyphylla was best for a shady slope, while a 6:4 ratio of K. tragus to B. dasyphylla was best for repair on a sunny slope of the degraded mine area. (4) Conclusion: This study provides a typical example of applying ecological theory in practice that will be useful for current and future studies and applications. This approach will ensure that governance efforts to restore degraded ecosystems are effective and efficient.
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Snyman, H. A., e W. L. J. Van Rensburg. "Hydrological cycle of natural veld in the Central Orange Free State". Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie 5, n. 4 (18 marzo 1986): 181–85. http://dx.doi.org/10.4102/satnt.v5i4.999.
Testo completoAbstract (sommario):
The hydrological cycle, which determines the water balance of the grazing ecosystem, is discussed. This cycle can be separated into a number of intermediate processes, each of which influences the water balance. These intermediate processes include surface runoff, evapotranspiration, percolation, infiltration and the storage of water in the ecosystem. Practical guidelines to increase the effectivity of the available rainfall for aboveground phytomass production, in arid and semi-arid regions, are discussed.
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Yang, Ting Ting, Peng Li, Peng Tao Liu e Xin Hong Wu. "Distribution of Grassland Biomass Carbon Storage in China". Advanced Materials Research 518-523 (maggio 2012): 183–88. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.183.
Testo completoAbstract (sommario):
Grassland ecosystems plays a very important role in the global carbon cycle，But measured data is very lack. In this paper, based on the ground survey data of grassland in fourteen provinces in 2008 and satellite remote sensing data, biomass carbon storage in grassland ecosystem in China is estimated. The main conclusions are as follows: China's total grassland area is about 331.41×104 km2, the total biomass carbon storage in grassland ecosystem in China in 2008 was 951.73 TgC, The carbon storage in aboveground and belowground were 161.99 and 789.74 TgC respectively. Carbon storage of Underground was about 5 times more than that of aboveground. China's grasslands are mainly located in the northern arid and semi-arid regions and Qinghai-Tibet Plateau. Inner Mongolia has the highest total vegetation carbon storage. Heilongjiang province is the area which has the highest above-ground biomass density, while the lowest area is Ningxia province. warm-temperate shrub-tussock provides the largest portion of carbon storage in Chinese grassland vegetation (29.66%).
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Bernardino, Paulo N., Wanda De Keersmaecker, Rasmus Fensholt, Jan Verbesselt, Ben Somers e Stéphanie Horion. "Global‐scale characterization of turning points in arid and semi‐arid ecosystem functioning". Global Ecology and Biogeography 29, n. 7 (7 aprile 2020): 1230–45. http://dx.doi.org/10.1111/geb.13099.
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Lu, Yayan, Xiaoliang Xu, Junhong Zhao e Fang Han. "Spatiotemporal Evolution of Mountainous Ecosystem Services in an Arid Region and Its Influencing Factors: A Case Study of the Tianshan Mountains in Xinjiang". Land 11, n. 12 (30 novembre 2022): 2164. http://dx.doi.org/10.3390/land11122164.
Testo completoAbstract (sommario):
Mountainous ecosystems provide humans with multiple ecosystem services (ESs), but global changes and anthropogenic activities threaten the supply of such services in arid regions. To maintain regional ecological security and achieve ecosystem sustainability, it is quite essential to understand the spatiotemporal characteristics of mountainous ESs in arid regions and clarify the main driving factors of different ESs. Using the integrated valuation of ecosystem services and tradeoffs (InVEST) and revised universal soil-loss equation (RUSLE) models, we evaluated the ESs provided by the Tianshan Mountains of Xinjiang from 2000 to 2020. The research showed that: (i) over the 20 years in question, habitat quality and carbon storage remained relatively stable, while soil retention and water yield fluctuated significantly. (ii) All ES pairs exhibited synergies. Spatial synergy areas were concentrated in the northwestern and southwestern areas; spatial trade-off areas alternated with spatial synergy areas. (iii) Hotspots with at least two ESs covered 73% of the study region. Middle- and high-altitude areas were the main supply areas of ES. (iv) Land-use types were the dominant driving factor of habitat quality and carbon storage, while mean annual precipitation had the strongest explanatory power for water yield. Soil retention was mainly affected by mean annual temperature and the normalized difference vegetation index. Our findings could provide guidance for policymakers when developing measures for ecosystem conservation and management.
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Rathore, Indira, e Jagadish Chandra Tarafdar. "Modified Labile Phosphorus Estimation Method for Arid Ecosystem". Communications in Soil Science and Plant Analysis 43, n. 11 (giugno 2012): 1542–49. http://dx.doi.org/10.1080/00103624.2012.675391.
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Kumar, Sudeep, e D. N. Sen. "Survival adaptations of threeEuphorbia spp. in arid ecosystem". Folia Geobotanica et Phytotaxonomica 20, n. 1 (marzo 1985): 57–66. http://dx.doi.org/10.1007/bf02856465.
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Salugin, A. N. "Simulation Modeling Grassland Ecosystem Degradation in Arid Regions". Russian Agricultural Sciences 49, n. 3 (giugno 2023): 233–36. http://dx.doi.org/10.3103/s106836742303014x.
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Zhang, Jinliang, Chao Zhang, Wensi Ma, Wei Wang e Haofei Li. "Improving the Model Performance of the Ecosystem Carbon Cycle by Integrating Soil Erosion–Related Processes". Atmosphere 14, n. 12 (23 novembre 2023): 1724. http://dx.doi.org/10.3390/atmos14121724.
Testo completoAbstract (sommario):
Soil erosion is a key factor in soil quality degradation and carbon balance in arid ecosystems. However, many models ignore the soil erosion process in arid regions, which may lead to limits in our understanding of ecosystem processes in arid regions. In this study, we added the soil erosion process according to field observed data of soil hydrothermal regimes and carbon flux. We validated this coupling version of IBIS (Integrated Biosphere Simulator) and RUSLE (RU–IBIS) by examining four different vegetation types and the carbon budget in the arid region on the Loess Plateau (LP). Our results indicated that the coupling model (RU–IBIS) produced more reliable simulations of the soil water content (with the r from 0.23–0.90 to 0.71–0.97) and evaporation (ET) (the average r was 0.76) and significantly improved the simulation of the leaf area index (LAI) (the average r was 0.95) and net primary production (NPP) (the average r was 0.95). We also conducted sensitivity experiments to determine how soil texture and aerodynamic roughness (Z0m) affect the soil water content. Moreover, it was revealed that specific leaf area (SLA) plays a key role in the simulation of NPP and NEE. Our study suggests that the coupled soil erosion process and parameterization can effectively improve the performance of IBIS in arid regions. These results need to be considered in future Earth system models.
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Jia, Zhi Feng, e Wen Bin Li. "Theoretical Study on Establishing Hydro-Eco Dynamic Monitoring System in Large-Scale and Arid Irrigation District". Advanced Materials Research 726-731 (agosto 2013): 3787–91. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.3787.
Testo completoAbstract (sommario):
As for some large-scale and arid irrigation district in China, such as Jinghuiqu irrigation district and Shihezi reclamation district, hydro-ecosystem was gradually degenerated and imbalanced due to water shortage and unreasonable exploitation. In order to study hydrological elements, water cycle process and ecological response caused by human activities and other factors, and improve the quality of hydro-ecosystem, scientific connotation of establishing hydro-eco dynamic monitoring system in large-scale and arid irrigation district was defined. Hydro-ecosystem dynamic monitoring indexes including meteorological elements, hydrological elements, ecological elements closely related to hydrological elements and cycle, and socio-economic elements were proposed. Comprehensive monitoring methods based on automatic monitoring net, remote sensing satellite monitoring, field test and investigation were determined, and overall framework of hydro-eco dynamic monitoring was designed, which provided a theoretical basis for establishing hydro-eco dynamic monitoring system in large-scale and arid irrigation district.
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Franco, André L. C., Laureano A. Gherardi, Cecilia M. de Tomasel, Walter S. Andriuzzi, Katharine E. Ankrom, E. Ashley Shaw, Elizabeth M. Bach, Osvaldo E. Sala e Diana H. Wall. "Drought suppresses soil predators and promotes root herbivores in mesic, but not in xeric grasslands". Proceedings of the National Academy of Sciences 116, n. 26 (11 giugno 2019): 12883–88. http://dx.doi.org/10.1073/pnas.1900572116.
Testo completoAbstract (sommario):
Precipitation changes among years and locations along gradients of mean annual precipitation (MAP). The way those changes interact and affect populations of soil organisms from arid to moist environments remains unknown. Temporal and spatial changes in precipitation could lead to shifts in functional composition of soil communities that are involved in key aspects of ecosystem functioning such as ecosystem primary production and carbon cycling. We experimentally reduced and increased growing-season precipitation for 2 y in field plots at arid, semiarid, and mesic grasslands to investigate temporal and spatial precipitation controls on the abundance and community functional composition of soil nematodes, a hyper-abundant and functionally diverse metazoan in terrestrial ecosystems. We found that total nematode abundance decreased with greater growing-season precipitation following increases in the abundance of predaceous nematodes that consumed and limited the abundance of nematodes lower in the trophic structure, including root feeders. The magnitude of these nematode responses to temporal changes in precipitation increased along the spatial gradient of long-term MAP, and significant effects only occurred at the mesic site. Contrary to the temporal pattern, nematode abundance increased with greater long-term MAP along the spatial gradient from arid to mesic grasslands. The projected increase in the frequency of extreme dry years in mesic grasslands will therefore weaken predation pressure belowground and increase populations of root-feeding nematodes, potentially leading to higher levels of plant infestation and plant damage that would exacerbate the negative effect of drought on ecosystem primary production and C cycling.
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Yan, Junjie, Guangpeng Zhang, Xiaoya Deng, Hongbo Ling, Hailiang Xu e Bin Guo. "Does Climate Change or Human Activity Lead to the Degradation in the Grassland Ecosystem in a Mountain-Basin System in an Arid Region of China?" Sustainability 11, n. 9 (7 maggio 2019): 2618. http://dx.doi.org/10.3390/su11092618.
Testo completoAbstract (sommario):
In mountain-basin systems in the arid region, grasslands are sensitive to the impacts of climate change and human activities. In this study, we aimed to resolve two key scientific issues: (1) distinguish and explain the laws of grassland ecosystem deterioration in a mountain-basin system and identify the key factors related; and (2) evaluate whether damaged grasslands ecosystem have the potential for natural revegetation. Hence, by combining spatial analysis with statistical methods, we studied the trends of the deterioration of the grassland ecosystem and its spatial characteristics in Kulusitai, a mountain-basin system in the arid region of Northwest China. According to our results, vegetation coverage and productivity exhibited significant decreasing trends, while the temperature vegetation drought index (TVDI) exhibited a significant increasing trend. Drainage of groundwater, because of increase in irrigation for the expanded irrigated area around Kulusitai, and climate warming were the critical triggers that leaded to the soil drought. Soil drought and overgrazing, resulting from the impact of human activities, were the main factors responsible for the deterioration of the grassland ecosystems. However, limiting the number of livestock to a reasonable scale and reducing the irrigated area may help to increase the soil moisture, thus promoting the germination of soil seed banks and facilitating the normal growth of grassland vegetation. Furthermore, based on analysis of the phenology of the grassland vegetation, the reasonable period for harvesting and storage is from July 29 to August 5. The results of this study provide a scientific basis and practical guide for restoring mountain-basin grassland systems in arid regions.