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1
Gorobtsova, Olga, Viktoria Chadaeva, Fatima Gedgafova, Tatyana Uligova, Rustam Tembotov et 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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Liu, Yang, Qianmei Chen, Zexi Wang, Haifeng Zheng, Yamei Chen, Xian Chen, Lifeng Wang, Hongjie Li et Jian Zhang. « Nitrogen Addition Alleviates Microbial Nitrogen Limitations and Promotes Soil Respiration in a Subalpine Coniferous Forest ». Forests 10, no 11 (16 novembre 2019) : 1038. http://dx.doi.org/10.3390/f10111038.
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Soil microbes are an important component of soil ecosystems that influence material circulation and are involved in the energy flow of ecosystems. The increase in atmospheric nitrogen (N) deposition affects all types of terrestrial ecosystems, including subalpine forests. In general, alpine and high-latitude ecosystems are N limited. Increased N deposition could therefore affect microbial activity and soil respiration. In this study, four levels of N addition, including CK (no N added), N1 (2 g m−2 a−1), N2 (5 g m−2 a−1), and N3 (10 g m−2 a−1), were carried out in a Sichuan redwood forest at the eastern edge of the Tibetan Plateau. The dynamics of soil respiration, major microbial groups, ecoenzymatic stoichiometry, and microbial biomass carbon and nitrogen (MBC and MBN, respectively) were investigated over a year. The results showed that N application significantly increased soil respiration (11%–15%), MBC (5%–9%), MBN (23%–34%), N-acetylglucosidase (56.40%–204.78%), and peroxidase (42.28%–54.87%) activities. The promotion of soil respiration, N-acetylglucosidase, and peroxidase was highest under the N2 treatment. The carbon, nitrogen, and phosphorus metabolism of soil microbes in subalpine forests significantly responded to N application. In the latter stages of N application, microbial metabolism changed from being N restricted to phosphorus restricted, especially under the N2 treatment. Soil bacteria (B) and gram-positive (G+) bacteria were the dominant microbial groups affecting soil respiration. Structural equation modelling indicated that N application significantly promoted soil respiration and microbial biomass, whereas the main microbial groups did not significantly respond to N application. Therefore, we conclude that short-term N addition alleviates microbial nitrogen limitation and promotes soil respiration in the subalpine forest ecosystem that accelerates soil carbon (C) and N cycling. Continuous monitoring is needed to elucidate the underlying mechanisms under long-term N deposition, which may help in forecasting C, N, and P cycling in the alpine region under global climate change.
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Stanton, Nancy, Steven Buskirk et Steve Miller. « Habitat Distribution of Small Mammal Communities in Grand Teton National Park ». UW National Parks Service Research Station Annual Reports 14 (1 janvier 1990) : 109–15. http://dx.doi.org/10.13001/uwnpsrc.1990.2903.
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Since Grand Teton National Park adopted a natural fire policy in the early 1970's, four major fires have burned within the park which created a chronosequence of post-burn successional ecosystems. The burns encompassed forests varying in composition from Englemann spruce (Picea englemanil) /subalpine fir (Abies lasiocarpa) /lodgepole pine (Pinus contorta) (Beaver Creek, Mystic Isle) to Englemn spruce / subalpine fir (Waterfalls Canyon) to primarily lodgepole pine (Huckleberry Mountain).
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Gray, Paul A. « Impacts of climate change on diversity in forested ecosystems : Some examples ». Forestry Chronicle 81, no 5 (1 septembre 2005) : 655–61. http://dx.doi.org/10.5558/tfc81655-5.
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Ecological diversity (the product of ecosystem, species, and genetic diversity) will change significantly in the 21st Century in response to the combined influence of climate, human activities, the movement of indigenous and non-indigenous species, and natural disturbances like fire (also modified by climate). Many species will acclimate (phenotypic variation) and/or adapt (genotypic variation) to changing conditions. Many will not. Species with a high rate of reproduction that are able to move long distances, rapidly colonize new habitats, tolerate humans, and survive within a broad range of biophysical conditions will be most successful in finding new niches. Large changes in ecosystem composition, structure, and function are expected to occur at northern latitudes and higher altitudes. In some areas novel ecosystems likely will replace existing subalpine, alpine, boreal forest, and tundra ecosystems. Key words: climate change, ecodiversity, forest, ecosystem diversity, species diversity, genetic diversity
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Chadaeva, V. A., N. L. Tsepkova et R. H. Pshegusov. « Climatogenic changes in meadow ecosystems in the Central Caucasus on the example of specially protected natural areas ». REPORTS ADYGE (CIRCASSIAN) INTERNATIONAL ACADEMY OF SCIENCES 22, no 1 (2022) : 57–70. http://dx.doi.org/10.47928/1726-9946-2022-22-1-57-70.
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The basic trends of vegetation dynamics in meadow ecosystems of the Central Caucasus under the impact of current climatic changes were revealed on the example of sub-alpine meadows of the National Park <<Prielbrusye>> and Sukan plot of the Kabardino-Balkarian State High-Mountain Reserve. In the past 20 years, in the mountains of the Central Caucasus, during the period of active vegetation, the temperature increased by 0,46~С and precipitation by 16,24 mm, respectively. Humid subalpine meadows, which are indicators of climatic changes, are therewith more susceptible to climatic changes. Significant changes were registered in the following geobotanical and ecological parameters per 6--7 years. Mesophytous subalpine meadows are less susceptible. Steppe subalpine meadows are insignificantly responsive to current climatic changes.
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JENKINS, MEAGHAN, et MARK A. ADAMS. « Vegetation type determines heterotrophic respiration in subalpine Australian ecosystems ». Global Change Biology 16, no 1 (janvier 2010) : 209–19. http://dx.doi.org/10.1111/j.1365-2486.2009.01954.x.
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Price, Karen, Rachel F. Holt et Dave Daust. « Conflicting portrayals of remaining old growth : the British Columbia case ». Canadian Journal of Forest Research 51, no 5 (mai 2021) : 742–52. http://dx.doi.org/10.1139/cjfr-2020-0453.
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Old growth is disappearing globally, with implications for biodiversity, forest resilience, and carbon storage; yet uncertainty remains about how much exists, partly because assessments stratify ecosystems differently, sometimes obscuring relevant patterns. This paper compares portrayals of British Columbia’s (BC) old-growth forest stratified in two ways: by biogeoclimatic variant, as per policy, and by relative site productivity. Our analyses confirm provincial government claims that about a quarter of BC’s forests are old growth but find that most of this area has low realized productivity, including subalpine and bog forests, and that less than 1% is highly productive old growth, growing large trees. Within biogeoclimatic variant, nearly half of high-productivity forest landscapes have less than 1% of the expected area of old forest. Low-productivity ecosystems are over-represented in protected forest. We suggest that the experiment of managing old growth solely by biogeoclimatic variant has failed and that current forest policy, in combination with timber harvesting priorities, does not maintain representative ecosystems, counter to the intent of both policy and international conventions. Stratifying old growth by relative productivity within biogeoclimatic variant seems an appropriate method to portray ecosystem representation, potentially increasing the probability of maintaining ecosystem resilience.
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Gedgafova, Fatima, Olga Gorobtsova, Tatyana Uligova, Rustam Tembotov et Elena Khakunova. « Biological activity of mountain meadow subalpine soils of Central Caucasus ». BIO Web of Conferences 35 (2021) : 00008. http://dx.doi.org/10.1051/bioconf/20213500008.
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Indicators of biological activity (humic content and stock, Cmic content and stock, hydrolytic and redox enzymes activity) were measured for the first time in the upper horizons of mountain meadow subalpine soils of Central Caucasus (elbrus altitudinal zonality in Kabardino-Balkaria). The comparative assessment was performed for the biological characteristics together with soil density and acid-base properties for soils of natural and pasture ecosystems. The integral index of ecological and biological soil state (IIEBSS) was calculated to estimate the level of changes in biological activity. It was shown that pasture degradation leads to 30% decrease of IIEBSS compared to the undisturbed soil. The defined biological parameters of natural undisturbed mountain meadow soils could be used as diagnostic indicators for the ecological studies of ecosystems under anthropogenic load.
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Brunswig, Robert H., et James P. Doerner. « Lawn Lake, a high montane hunting camp in the Colorado (USA) rocky mountains : Insights into early Holocene Late Paleoindian hunter-gatherer adaptations and paleo-landscapes ». North American Archaeologist 42, no 1 (14 septembre 2020) : 5–44. http://dx.doi.org/10.1177/0197693120958352.
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The Lawn Lake site is a stratified hunting camp situated on a glacial lake outlet river terrace in Rocky Mountain National Park’s upper subalpine forest zone. Its archaeological assemblage represents 9,000 years of hunter-gatherer use as a summer game and plant processing camp for subalpine forest and nearby alpine tundra resource areas. This article’s focus is on the site’s earliest camp levels which contain artifacts and AMS radiocarbon dated hearth charcoal between 8,900 and 7,900 cal yr BP, placing them among the region’s earliest high montane (3,353 m ASL) Paleoindian hunting camps, once part of a network of such sites designed to support systematic high altitude procurement of summer migratory game animals and plant foods in Southern Rocky Mountain subalpine forest and tundra ecosystems. Lawn Lake paleoclimate and paleoecology studies produced long-term pollen records and climate-proxy sediment data for modeling the site’s prehistoric climate and ecology history, useful for interpreting its high-altitude Late Paleoindian hunter-gatherer adaptations.
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Peterson, David W., David L. Peterson et Gregory J. Ettl. « Growth responses of subalpine fir to climatic variability in the Pacific Northwest ». Canadian Journal of Forest Research 32, no 9 (1 septembre 2002) : 1503–17. http://dx.doi.org/10.1139/x02-072.
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We studied regional variation in growth-limiting factors and responses to climatic variability in subalpine forests by analyzing growth patterns for 28 tree-ring growth chronologies from subalpine fir (Abies lasiocarpa (Hook.) Nutt.) stands in the Cascade and Olympic Mountains (Washington and Oregon, U.S.A.). Factor analysis identified four distinct time series of common growth patterns; the dominant growth pattern at any site varied with annual precipitation and temperature (elevation). Throughout much of the region, growth is negatively correlated with winter precipitation and spring snowpack depth, indicating that growth is limited primarily by short growing seasons. On the driest and warmest sites, growth is negatively correlated with previous summer temperature, suggesting that low summer soil moisture limits growth. Growth patterns in two regions were sensitive to climatic variability associated with the Pacific Decadal Oscillation, apparently responding to low-frequency variation in spring snowpack and summer soil moisture (one negatively, one positively). This regional-scale analysis shows that subalpine fir growth in the Cascades and Olympics is limited by different climatic factors in different subregional climates. Climategrowth relationships are similar to those for a co-occurring species, mountain hemlock (Tsuga mertensiana (Bong.) Carrière), suggesting broad biogeographic patterns of response to climatic variability and change by subalpine forest ecosystems in the Pacific Northwest.
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Scanes, Peter Raymond, Adam McSorley et Adrian Dickson. « Feral horses (Equus caballus) increase suspended sediment in subalpine streams ». Marine and Freshwater Research 72, no 9 (2021) : 1290. http://dx.doi.org/10.1071/mf20353.
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Feral horses preferentially utilise aquatic landscape elements. Damage to stream banks by feral horses potentially degrades water quality and affects aquatic ecosystems. Despite the global predominance of horse activity in or near water, there is poor understanding of in-stream impacts. Motion-sensing cameras were used near subalpine streams to quantify frequency and behaviour of horses interacting with streams. Deployed turbidity loggers were used to indicate the presence of suspended sediment from interactions and to assess long-term (3 year) seasonal suspended sediment regime at sites with very small and large amounts of horse activity. In summer, 99.9% of large grazer interactions with streams were horses and we estimate 130 horse interactions per kilometre of stream per day, resulting in stream turbidity increases up to 100 NTU. Long-term turbidity at sites with greater riparian damage from horses was significantly greater than at control sites. Turbidity in horse-affected streams peaked at 50 times the national turbidity guideline and, in summer, averaged eight times the guideline. Suspended sediment leads to a high risk of loss of aquatic diversity and impairment of ecosystem function. Linear relationships between turbidity and riparian damage suggest that any level of horse presence affects subalpine waterways.
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Hamilton, Evelyn H., et Sybille Haeussler. « Modeling stability and resilience after slashburning across a sub-boreal to subalpine forest gradient in British Columbia ». Canadian Journal of Forest Research 38, no 2 (février 2008) : 304–16. http://dx.doi.org/10.1139/x07-098.
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Stability and resilience of conifer-dominated vegetation communities following clear-cutting and slashburning in central British Columbia, were modeled across gradients of resource availability, fire return interval (FRI), and fire severity. We hypothesized that high resource availability and long fire-free intervals would enhance stability, whereas high resource availability and short fire-free intervals would confer resilience. Fire weather indices and pre- and post-burn fuel loads were recorded and vegetation regrowth monitored for 5–11 years at 12 sites. Stepwise regression was used to model rates of revegetation, increases in vascular species richness, and pre- and post-burn similarity of species composition as a function of the environmental variables. Predicted stability for four sub-boreal to subalpine vegetation communities with contrasting resource availability and FRI corresponded closely to our hypotheses. Rates of revegetation were more strongly correlated with resource availability, whereas composition-based response variables were more strongly correlated with the FRI. Based on revegetation rates, all ecosystems were predicted to have equal resilience. However, based on vegetation composition, mesic sub-boreal ecosystems were predicted to be more resilient than mesic subalpine ecosystems because the degree of change in species composition was less sensitive to increasing burn severity. More slashburned sites with a broader range of burn severities are needed to verify these preliminary models.
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Klenner, Walt, et Thomas P. Sullivan. « Partial and clear-cut harvesting of high-elevation sprucefir forests : implications for small mammal communities ». Canadian Journal of Forest Research 33, no 12 (1 décembre 2003) : 2283–96. http://dx.doi.org/10.1139/x03-142.
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Subalpine spruce (Picea) fir (Abies) forests occur throughout the Cordillera of western North America. A variety of alternative silvicultural systems to clear-cutting are being investigated in these high-elevation forests in terms of their impacts on ecosystem components. We tested the hypotheses that abundance, reproduction, and survival of populations of (i) southern red-backed voles (Clethrionomys gapperi Vigors) will decline, (ii) long-tailed voles (Microtus longicaudus Merriam) and northwestern chipmunks (Tamias amoenus J.A. Allen) will increase, and (iii) deer mice (Peromyscus maniculatus Wagner) will be similar, with respect to decreasing levels of tree retention. Small mammal populations were live-trapped from 1994 to 1998 in replicated sites of uncut forest, single tree selection, 0.1-ha patch cuts, 1.0-ha patch cuts, a 10.0-ha clearcut, and edges in an Engelmann spruce (Picea engelmannii Parry ex Engelm.) subalpine fir (Abies lasiocarpa (Hook.) Nutt.) forest near Sicamous, British Columbia, Canada. Clethrion omys gapperi dominated the small mammal community, reaching a peak abundance of 80 animals/ha with mean values ranging from 31 to 50 animals/ha. Over the 4 postharvest years, abundance, reproduction, and survival of C. gapperi populations were consistently similar among uncut forest, single tree selection, and patch cut treatments compared with clear-cut sites where this species declined to extirpation. Microtus longicaudus and T. amoenus occurred predominantly in clearcut sites, whereas P. maniculatus was present in low numbers on all sites. With respect to small mammals, partial harvesting systems appear to provide a means for combining timber extraction with maintenance of mature forest habitat in these subalpine ecosystems.
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Heinrichs, Markus L., Martin G. Evans, Richard J. Hebda, Ian R. Walker, Samantha L. Palmer et Sandra M. Rosenberg. « Holocene Climatic Change and Landscape Response at Cathedral Provincial Park, British Columbia, Canada ». Géographie physique et Quaternaire 58, no 1 (26 juin 2006) : 123–39. http://dx.doi.org/10.7202/013113ar.
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Abstract Environmental sensitivity to temperature change was established by comparing pollen, plant macrofossils, macroscopic charcoal, and sediment yield data from Lake of the Woods, Cathedral Provincial Park in the Cascade Mountains of southern British Columbia, Canada, to an independent record of midge-inferred paleotemperature. Steppe vegetation with some spruce and fir occurred initially, developing into pine forests in the warm early Holocene. These forests burned often, preventing spruce and fir succession. Once established, the forests retained an Engelmann Spruce-Subalpine Fir character. After 8000 cal BP, in warm but wetter conditions, the forest contained less pine and fires burned less frequently. About 4000 cal BP, cooler temperatures resulted in closure of the Engelmann Spruce-Subalpine Fir forests and a further reduction in fire frequency. Sediment yield results suggest a stable environment throughout the Holocene, likely due to sediment trapping in two upstream lakes. Midge-inferred temperatures correspond closely with a consensus reconstruction of temperatures from southern British Columbia, however Cathedral Provincial Park terrestrial ecosystems were not as sensitive to past climate change when compared to other nearby Engelmann Spruce-Subalpine Fir sites.
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Risch, Anita C., Martin F. Jurgensen, Deborah S. Page-Dumroese, Otto Wildi et Martin Schütz. « Long-term development of above- and below-ground carbon stocks following land-use change in subalpine ecosystems of the Swiss National Park ». Canadian Journal of Forest Research 38, no 6 (juin 2008) : 1590–602. http://dx.doi.org/10.1139/x08-014.
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Vegetation changes following agricultural land abandonment at high elevation — which is frequent in Europe — could have a major impact on carbon (C) sequestration. However, most information on the effects of vegetation changes on ecosystem C stocks originates from low-elevation studies on reforestation or early successional forests, and little is known about how these stocks change during long-term secondary forest succession and at high elevation. We assessed aboveground, belowground, and ecosystem organic matter and C stocks in high-elevation ecosystems that represent the long-term development (centuries) following land abandonment: short- and tall-grass pastures, Swiss mountain pine (Pinus mugo Turra), mixed-conifer, and Swiss stone pine ( Pinus cembra L.) – European larch ( Larix decidua P. Mill.) forests. Aboveground C stocks were lowest in the short-grass pastures (0.1 Mg C·ha–1) and reached a maximum in the mixed-conifer and stone pine – larch forests (166 Mg C·ha–1). Belowground C stocks did not differ among the ecosystems studied. We only detected ecosystem C sequestration during reforestation; whereas no significant differences in ecosystem C stocks were found during long-term secondary forest development. Our calculations showed that only an additional 1733–3032 Mg C·year–1 would be sequestered owing to natural reforestation in high-elevation Switzerland, which likely can be considered negligible compared with total annual C sequestration calculated for Swiss forests in other studies.
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Gharun, Mana, Lukas Hörtnagl, Eugénie Paul-Limoges, Shiva Ghiasi, Iris Feigenwinter, Susanne Burri, Kristiina Marquardt et al. « Physiological response of Swiss ecosystems to 2018 drought across plant types and elevation ». Philosophical Transactions of the Royal Society B : Biological Sciences 375, no 1810 (7 septembre 2020) : 20190521. http://dx.doi.org/10.1098/rstb.2019.0521.
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Using five eddy covariance flux sites (two forests and three grasslands), we investigated ecosystem physiological responses to the 2018 drought across elevational gradients in Switzerland. Flux measurements showed that at lower elevation sites (below 1000 m.a.s.l.; grassland and mixed forest) annual ecosystem productivity (GPP) declined by approximately 20% compared to the previous 2 years (2016 and 2017), which led to a reduced annual net ecosystem productivity (NEP). At the high elevation sites, however, GPP increased by approximately 14% and as a result NEP increased in the alpine and montane grasslands, but not in the subalpine coniferous forest. There, increased ecosystem respiration led to a reduced annual NEP, despite increased GPP and lengthening of the growing period. Among all ecosystems, the coniferous forest showed the most pronounced negative stomatal response to atmospheric dryness (i.e. vapour pressure deficit, VPD) that resulted in a decline in surface conductance and an increased water-use efficiency during drought. While increased temperature enhanced the water-use efficiency of both forests, de-coupling of GPP from evapotranspiration at the low-elevation grassland site negatively affected water-use efficiency due to non-stomatal reductions in photosynthesis. Our results show that hot droughts (such as in 2018) lead to different responses across plants types, and thus ecosystems. Particularly grasslands at lower elevations are the most vulnerable ecosystems to negative impacts of future drought in Switzerland. 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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Chadaeva, Victoria, Olga Gorobtsova, Rustam Pshegusov, Nelli Tsepkova, Rustam Tembotov, Zalim Khanov, Fatima Gedgafova et al. « Stages of grassland degradation in subalpine ecosystems of the Central Caucasus, Russia ». Chilean journal of agricultural research 81, no 4 (décembre 2021) : 630–42. http://dx.doi.org/10.4067/s0718-58392021000400630.
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Brigham, Laurel M., Ellen H. Esch, Christopher W. Kopp et Elsa E. Cleland. « Warming and shrub encroachment decrease decomposition in arid alpine and subalpine ecosystems ». Arctic, Antarctic, and Alpine Research 50, no 1 (1 janvier 2018) : e1494941. http://dx.doi.org/10.1080/15230430.2018.1494941.
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Novruzov, V., et G. Kulieva. « Floristic Diversity of the Intrazonal Ecosystem of the Tovuzchay Basin Subalpine Belt ». Bulletin of Science and Practice 7, no 5 (15 mai 2021) : 18–23. http://dx.doi.org/10.33619/2414-2948/66/02.
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The preservation of the biodiversity of mountain ecosystems is one of the independent problems of mountain regions. The formation and development of vegetation in the subalpine belt is largely determined by the ecological conditions of their habitat. Strongly sparse groups of cold-resistant plants, represented by hyperkryophytes and hemicryophytes: perennials of short stature, pillows, mosses and lichens, adapted to various habitats, are of predominant importance. The flora of the studied meadow communities is distributed according to the main taxonomic groups as follows: lichens 25%, spore 2%, conifers 13%, flowering 58%. Of the higher vascular plants, 45 species grow here, all flowering plants are combined into 20 families and 38 genera. In terms of life expectancy, all species are perennials, the main part of which, in terms of the rhythm of development, belongs to summer-green species. The article describes the flora of the subalpine belt of the Tovuzchay basin.
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Zhou, Hongyang, Kaiwen Pan, Xiaoming Sun, Belayneh Azene, Piotr Gruba, Xiaogang Wu, Lin Zhang, Meng Zhang, Tianwen Tang et Renhuan Zhu. « Environmental Factors Indirectly Impact the Nematode Carbon Budget of Subalpine Spruce Forests ». Forests 13, no 3 (16 mars 2022) : 462. http://dx.doi.org/10.3390/f13030462.
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Nematodes play a significant role in soil biogeochemical cycling. However, our understanding of their community carbon budget response for a shift in the environmental conditions of natural and planted forests is limited. Therefore, we investigated the nematode community composition, daily carbon used in production and daily carbon budget, environmental variables, and the interaction among trophic groups in the moss, litter and 0–5 cm soil layers of natural subalpine spruce forest and plantations in western Sichuan, China. The result revealed that plantations increased the total nematode daily carbon budget by approximately 52% through the herbivore channel in the 0–5 cm soil layer. The herbivorous nematodes’ daily carbon budget and production in the moss layer of plantations decreased by approximately 60% compared to natural forests. Nematode daily carbon used in production and carbon budget had a strong negative correlation with genus richness. The water content and total carbon was the most important environmental factor that affected the nematode carbon budget and production, respectively. However, the environmental factors indirectly affect the daily carbon budget of herbivore nematodes through omnivore top-down control in subalpine forest ecosystems. Our findings highlight that the planted ecosystems have a certain capacity to maintain abundance, richness, and carbon budget of soil nematode but increase the risk of herbivorous pests.
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Zhu, Guiqing, Chaoxiang Yuan, Hede Gong, Yanling Peng, Changjiang Huang, Chuansheng Wu et Huachao Duan. « Effects of short-term grazing prohibition on soil physical and chemical properties of meadows in Southwest China ». PeerJ 9 (8 juin 2021) : e11598. http://dx.doi.org/10.7717/peerj.11598.
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Background Grassland plays an important role in the ecosystem, but overgrazing harms the grassland system in many places. Grazing prohibition is an effective method to restore grassland ecosystems, and it plays a great role in realizing the sustainable development of grassland systems. Therefore, it is necessary to carry out research on the influence of regional grazing prohibition on the physical and chemical properties of different grassland systems. Methods In Potatso National Park, Southwest China, we selected experimental plots in the artificial grazing meadow area to study the effects of grazing prohibition on plant and soil indexes in subalpine meadows and swamp meadows. We investigated the biomass and species diversity of grazing prohibition treatment and grazing treatment plots and sampled and tested the soil index. The variation percentage was used to remove the original heterogeneity and yearly variation, allowing us to compare differences in plant index and soil index values between grazing prohibition and grazing treatments. Results Grazing prohibition increased the aboveground biomass, total biomass, total meadow coverage, average height, richness index, Shannon diversity index and evenness index and reduced the belowground biomass and root/shoot ratio in the subalpine meadow and swamp meadow. Additionally, grazing prohibition reduced the pH and soil bulk density and increased the soil total carbon, soil organic carbon, soil total nitrogen, soil hydrolyzable nitrogen, soil total phosphorus and soil available phosphorus in the subalpine meadow and swamp meadow. Nonmetric multidimensional scaling (NMDS) analysis showed that both plant indexes and soil indexes were significantly different between grazing and grazing prohibition treatments and between meadow types. Short-term grazing prohibition had a great impact on improving the fertility of meadow soil in the study area. We suggest that long-term and extensive research should be carried out to promote the restoration and sustainable development of regional grassland systems.
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Makishima, Daichi, Rui Sutou, Akihito Goto, Yutaka Kawai, Naohiro Ishii, Hayami Taniguchi, Kei Uchida et al. « Potential extinction debt due to habitat loss and fragmentation in subalpine moorland ecosystems ». Plant Ecology 222, no 4 (24 février 2021) : 445–57. http://dx.doi.org/10.1007/s11258-021-01118-4.
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Sangüesa‐Barreda, Gabriel, Jan Esper, Ulf Büntgen, J. Julio Camarero, Alfredo Di Filippo, Michele Baliva et Gianluca Piovesan. « Climate–human interactions contributed to historical forest recruitment dynamics in Mediterranean subalpine ecosystems ». Global Change Biology 26, no 9 (13 juillet 2020) : 4988–97. http://dx.doi.org/10.1111/gcb.15246.
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Higuera, Philip E., Bryan N. Shuman et Kyra D. Wolf. « Rocky Mountain subalpine forests now burning more than any time in recent millennia ». Proceedings of the National Academy of Sciences 118, no 25 (14 juin 2021) : e2103135118. http://dx.doi.org/10.1073/pnas.2103135118.
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The 2020 fire season punctuated a decades-long trend of increased fire activity across the western United States, nearly doubling the total area burned in the central Rocky Mountains since 1984. Understanding the causes and implications of such extreme fire seasons, particularly in subalpine forests that have historically burned infrequently, requires a long-term perspective not afforded by observational records. We place 21st century fire activity in subalpine forests in the context of climate and fire history spanning the past 2,000 y using a unique network of 20 paleofire records. Largely because of extensive burning in 2020, the 21st century fire rotation period is now 117 y, reflecting nearly double the average rate of burning over the past 2,000 y. More strikingly, contemporary rates of burning are now 22% higher than the maximum rate reconstructed over the past two millennia, during the early Medieval Climate Anomaly (MCA) (770 to 870 Common Era), when Northern Hemisphere temperatures were ∼0.3 °C above the 20th century average. The 2020 fire season thus exemplifies how extreme events are demarcating newly emerging fire regimes as climate warms. With 21st century temperatures now surpassing those during the MCA, fire activity in Rocky Mountain subalpine forests is exceeding the range of variability that shaped these ecosystems for millennia.
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Hiramatsu, Shinichi, et Nisikawa Usio. « Assemblage Characteristics and Habitat Specificity of Carabid Beetles in a Japanese Alpine-Subalpine Zone ». Psyche : A Journal of Entomology 2018 (2018) : 1–15. http://dx.doi.org/10.1155/2018/9754376.
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In lowland areas of the world and high-altitude European mountains, the species compositions, body sizes, and wing forms of carabid beetles are known to change according to vegetation structures. However, little is known regarding the assemblage structure and habitat associations of carabid beetles in Japanese alpine-subalpine areas. We surveyed carabid beetles in four habitats (snow beds, alpine meadows, Pinus scrub, and fell-fields) in the alpine-subalpine zone on Mt. Hakusan, Japan. We surveyed carabid beetles six times between mid-July and late September. Nonmetric multidimensional scaling (NMDS) and analysis of similarities (ANOSIM) revealed three distinct carabid beetle assemblages in snow beds and alpine meadows, Pinus scrub, and fell-fields. The carabid beetle assemblages in the four habitats consisted predominantly of small and/or wingless species with differential spatiotemporal variability in abundance. Biota-environment (BIO-ENV) analyses showed that the percentage coverage by Pinus scrub, soil water content, and ground surface temperature were among the most significant variables affecting carabid beetle compositions. Given their small sizes and reduced wings, which are characteristic traits for limited mobility, and high-level habitat specificity, carabid beetles in the alpine-subalpine zone may serve as an important target group to monitor the impacts of global environmental change on mountain ecosystems.
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Volk, Matthias, Jan Enderle et Seraina Bassin. « Subalpine grassland carbon balance during 7 years of increased atmospheric N deposition ». Biogeosciences 13, no 12 (1 juillet 2016) : 3807–17. http://dx.doi.org/10.5194/bg-13-3807-2016.
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Abstract. Air pollution agents interact when affecting biological sinks for atmospheric CO2, e.g., the soil organic carbon (SOC) content of grassland ecosystems. Factors favoring plant productivity, like atmospheric N deposition, are usually considered to favor SOC storage. In a 7-year experiment in subalpine grassland under N- and O3-deposition treatment, we examined C fluxes and pools. Total N deposition was 4, 9, 14, 29 and 54 kg N ha−1 yr−1 (N4, N9, etc.); annual mean phytotoxic O3 dose was 49, 65 and 89 mmol m−2 projected leaf area. We hypothesized that between years SOC of this mature ecosystem would not change in control treatments and that effects of air pollutants are similar for plant yield, net ecosystem productivity (NEP) and SOC content, leading to SOC content increasing with N deposition. Cumulative plant yield showed a significant N and N × N effect (+38 % in N54) but no O3 effect. In the control treatment SOC increased significantly by 9 % in 7 years. Cumulative NEP did show a strong, hump-shaped response pattern to N deposition with a +62 % increase in N14 and only +39 % increase in N54 (N effect statistically not significant, N × N interaction not testable). SOC had a similar but not significant response to N, with highest C gains at intermediate N deposition rates, suggesting a unimodal response with a marginal (P = 0.09) N × N interaction. We assume the strong, pollutant-independent soil C sink developed as a consequence of the management change from grazing to cutting. The non-parallel response of SOC and NEP compared to plant yield under N deposition is likely the result of increased respiratory SOC losses, following mitigated microbial N-limitation or priming effects, and a shift in plant C allocation leading to smaller C input from roots.
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Alados, C. L., H. Saiz, P. Nuche, M. Gartzia, B. Komac, Á. De Frutos et Y. Pueyo. « Clearing vs. burning for restoring Pyrenean grasslands after shrub encroachment ». Cuadernos de Investigación Geográfica 45, no 2 (4 septembre 2019) : 441. http://dx.doi.org/10.18172/cig.3589.
Texte intégralRésumé :
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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Xu, Zhenfeng, Qing Liu et Huajun Yin. « Effects of temperature on soil net nitrogen mineralisation in two contrasting forests on the eastern Tibetan Plateau, China ». Soil Research 52, no 6 (2014) : 562. http://dx.doi.org/10.1071/sr13298.
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Intact soil cores from two adjacent forest ecosystems (natural coniferous forest and dragon spruce plantation) were incubated in the laboratory to examine effects of temperature, reforestation and their interactions on rates of nitrogen (N) mineralisation, nitrification and ammonification in the subalpine forest of the eastern Tibetan Plateau. Two contrasting soils were incubated at five temperatures (–5, 0, 5, 15 and 25°C) for 4 weeks. Rates of N mineralisation and nitrification were insensitive to temperature at lower temperatures (0°C and 5°C) but increased over higher temperatures (15°C and 25°C). Large amounts of ammonium were released for each incubation time in both soils when the incubation temperature was –5°C. Therefore, the rates of mineralisation and ammonification at –5°C were significantly higher than at the other temperatures. Both the accumulations of inorganic N and rates of N transformation were significantly higher in the natural forest than in the plantation. Moreover, temperature sensitivity of net nitrification and N mineralisation were greater in the natural forest than the spruce plantation. Effects of temperature on accumulations of inorganic N and rates of N transformation were dependent on incubation time and forest ecosystem. Our results suggested that –5°C might be a key low temperature for N mineralisation in subalpine forest on the eastern Tibetan Plateau; the effect of projected warming on soil N transformation rate may be less significant in plantation forests than natural forests in this specific region.
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Varricchione, Marco, Maria Laura Carranza, Valter Di Cecco, Luciano Di Martino et Angela Stanisci. « Warmer and Poorer : The Fate of Alpine Calcareous Grasslands in Central Apennines (Italy) ». Diversity 14, no 9 (23 août 2022) : 695. http://dx.doi.org/10.3390/d14090695.
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Global change threatens alpine biodiversity and its effects vary across habitat types and biogeographic regions. We explored vegetation changes over the last 20 years on two Mediterranean alpine calcareous grasslands in central Apennines (Italy): stripped grasslands (EUNIS code E4.436) with Sesleria juncifolia growing on steep slopes, and wind edge swards (EUNIS code E4.42) with Carex myosuroides. Based on a re-visitation of 25 vegetation plots of 4 × 4 m, we assessed changes in overall and endemic plant species cover and richness by nonparametric Kruskal–Wallis test. We explored changes in structure and ecology using growth forms and Landolt indicators for temperatures. We identified species’ contribution to temporal changes using the similarity percentage procedure (SIMPER). The results evidenced a significant decline in all species cover and richness on both plant communities with a significant decline in alpine and endemic species and in hemicryptophytes with rosette and scapose ones on stripped grasslands, as well as a decline in subalpine and suffruticose chamaephytes species on wind edge swards. Such biodiversity loss, so far observed only in the warmest and Southern Mediterranean summits of Europe, is likely attributable to the combined effect of higher temperatures; the increase in the vegetative period; and the decrease in water availability, which is particularly severe in calcareous regions. Our study suggested the vulnerability of the analyzed alpine ecosystems to global change and the importance of monitoring activities to better understand vegetation trends and adaptation strategies in subalpine, alpine, and nival ecosystems.
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Courtney Mustaphi, Colin J., et Michael F. J. Pisaric. « Holocene climate–fire–vegetation interactions at a subalpine watershed in southeastern British Columbia, Canada ». Quaternary Research 81, no 2 (mars 2014) : 228–39. http://dx.doi.org/10.1016/j.yqres.2013.12.002.
Texte intégralRésumé :
AbstractVegetation assemblages and associated disturbance regimes are spatially heterogeneous in mountain ecosystems throughout the world due to the complex terrain and strong environmental gradients. Given this complexity, numerous sites describing postglacial vegetation and fire histories are needed to adequately understand forest development and ecosystem responses to varying climate and disturbance regimes. To gain insight into long-term historical climate–fire–vegetation interactions in southeastern British Columbia, Canada, sedimentological and paleoecological analyses were performed on a sediment core recovered from a small subalpine lake. The pollen assemblages, stomata, and macroremains indicate that from 9500 to 7500 cal yr BP, Pinus-dominated forests occurred within the catchment and Alnus was also present. Climate was an important control of fire and fire frequency was highest at this time, peaking at 8 fires 1000 yr− 1, yet charcoal accumulation rates were low, indicative of low terrestrial biomass abundance. From 7500 to 4600 cal yr BP, Pinus decreased as Picea, Abies and Larix increased and fire frequencies decreased to 3–6 fires 1000 yr− 1. Since 7500 cal yr BP the fire regime varied at a millennial scale, driven by forest biomass abundance and fuel accumulation changes. Local scale (bottom-up) controls of fire increased in relative importance since at least 6000 cal yr BP.
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Hou, Jianfeng, Fei Li, Zhihui Wang, Xuqing Li et Wanqin Yang. « Budget of Plant Litter and Litter Carbon in the Subalpine Forest Streams ». Forests 12, no 12 (13 décembre 2021) : 1764. http://dx.doi.org/10.3390/f12121764.
Texte intégralRésumé :
Investigations on the budget of plant litter and litter carbon in forest streams can provide a key scientific basis for understanding the biogeochemical linkages of terrestrial–aquatic ecosystems and managing forest catchments. To understand the biogeochemical linkages among mountain forests, riparian vegetation, and aquatic ecosystems, the changes in litter input and output from the subalpine streams with stream characteristics and critical periods were investigated in an ecologically important subalpine coniferous forest catchment in the upper reaches of the Yangtze River. The annual litter input to the stream was 20.14 g m−2 and ranged from 2.47 to 103.13 g m−2 for 15 streams during the one-year investigation. Simultaneously, the litter carbon input to the stream was 8.61 mg m−2 and ranged from 0.11 to 40.57 mg m−2. Meanwhile, the annual litter output varied from 0.02 to 22.30 g m−2, and the average value was 0.56 g m−2. Correspondingly, the litter carbon output varied from 0.01 to 1.51 mg m−2, and the average value was 0.16 mg m−2. Furthermore, the average ratio of litter carbon input to output was 270.01. The maximum and minimum values were observed in the late growing season and the snowmelt season, respectively. Additionally, seasonal variations in temperature, together with the stream length, dominated the input of litter and litter carbon to the stream, while the precipitation, temperature, water level, and sediment depth largely determined their output. Briefly, the seasonal dynamics of litter and litter carbon were dominated by stream characteristics and precipitation as well as temperature patterns.
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Chen, Youchao, Ji Luo, Wei Li, Dong Yu et Jia She. « Comparison of soil respiration among three different subalpine ecosystems on eastern Tibetan Plateau, China ». Soil Science and Plant Nutrition 60, no 2 (4 mars 2014) : 231–41. http://dx.doi.org/10.1080/00380768.2013.873991.
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Fréjaville, Thibaut, Christopher Carcaillet et Thomas Curt. « Calibration of charcoal production from trees biomass for soil charcoal analyses in subalpine ecosystems ». Quaternary International 289 (mars 2013) : 16–23. http://dx.doi.org/10.1016/j.quaint.2012.02.043.
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Wang, Xueying, Guixiang Li, Yuxin Zhang et Keming Ma. « Contrasting Patterns and Drivers of Soil Fungal Communities between Two Ecosystems Divided by the Treeline ». Microorganisms 9, no 11 (2 novembre 2021) : 2280. http://dx.doi.org/10.3390/microorganisms9112280.
Texte intégralRésumé :
The treeline is a sensitive region of the terrestrial ecosystem responding to climate change. However, studies on the composition and formation mechanisms of soil fungal communities across the treeline are still lacking. In this study, we investigated the patterns of soil fungal community composition and interactions among functional guilds above and below the treeline using Illumina high-throughput sequencing and ecological network analysis. The results showed that there were significant differences in the soil environment and soil fungal community composition between the two ecosystems above and below the treeline. At the local scale of this study, geographic distance and environmental factors affected the composition of the soil fungal community. Soil temperature was an important environmental predictor of soil fungal community composition. Species in soil fungal communities in the subalpine meadow were more closely related to each other compared to those in the montane forest. Furthermore, the soil fungal community in montane forest was more stable. Our findings contribute to a better understanding of how mountain ecological functions respond to global climate change.
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Esch, Evan D., John R. Spence et David W. Langor. « Saproxylic beetle (Coleoptera) diversity in subalpine whitebark pine and lodgepole pine (Pinaceae) trees killed by mountain pine beetles (Coleoptera : Curculionidae) ». Canadian Entomologist 148, no 5 (11 mars 2016) : 556–68. http://dx.doi.org/10.4039/tce.2016.3.
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AbstractWhitebark pine,Pinus albicaulisEngelmann (Pinaceae), a foundational species of North American subalpine ecosystems, is endangered across its range and continued decline is inevitable. Little is known about the invertebrate fauna associated with this species which, if specific to whitebark pine, may also be threatened or endangered. We compared the composition of saproxylic beetle assemblages associated with whitebark pine and co-occurring lodgepole pine,Pinus contorta latifolia(Engelmann) Critchfield (Pinaceae), recently killed by mountain pine beetle (MPB),Dendroctonus ponderosaeHopkins (Coleoptera: Curculionidae), in subalpine forests in Alberta, Canada. Redundancy and rarefaction analyses revealed that beetle assemblage composition was influenced by snag class (i.e., time since death) but differed little among the two pine species within snag classes. However, a subset of the assemblage known to be associated with the MPB differed significantly in composition between the two pines. No common species were exclusively associated with whitebark pines; however, seven species were rarely collected only on whitebark pine. With the possible exception of these rare species, felling and burning infested whitebark pines to control the MPB will not likely endanger saproxylic beetles associated with this tree.
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He, Heliang, Lan Yu, Xiaocheng Yang, Lin Luo, Jia Liu, Jing Chen, Yongping Kou, Wenqiang Zhao et Qing Liu. « Effects of Different Soils on the Biomass and Photosynthesis of Rumex nepalensis in Subalpine Region of Southwestern China ». Forests 13, no 1 (5 janvier 2022) : 73. http://dx.doi.org/10.3390/f13010073.
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The performance of Rumex nepalensis, an important medicinal herb, varies significantly among subalpine grasslands, shrublands and forest ecosystems in southwestern China. Plant–soil feedback is receiving increasing interest as an important driver influencing plant growth and population dynamics. However, the feedback effects of soils from different ecosystems on R. nepalensis remain poorly understood. A greenhouse experiment was carried out to identify the effects of different soil sources on the photosynthesis and biomass of R. nepalensis. R. nepalensis was grown in soils collected from the rooting zones of R. nepalensis (a grassland soil, RS treatment), Hippophae rhamnoides (a shrub soil, HS treatment), and Picea asperata (a forest soil, PS treatment). The chlorophyll contents, net photosynthetic rates, and biomasses of R. nepalensis differed significantly among the three soils and followed the order of RS > HS > PS. After soil sterilization, these plant parameters followed the order of RS > PS > HS. The total biomass was 16.5 times higher in sterilized PS than in unsterilized PS, indicating that the existence of soil microbes in P. asperata forest ecosystems could strongly inhibit R. nepalensis growth. The root to shoot biomass ratio of R. nepalensis was the highest in the sterilized PS but the lowest in the unsterilized PS, which showed that soil microbes in PS could change the biomass allocation. Constrained redundancy analysis and path analysis suggested that soil microbes could impact the growth of R. nepalensis via the activities of soil extracellular enzymes (e.g., β-1,4-N-acetylglucosaminidase (NAG)) in live soils. The soil total soluble nitrogen concentration might be the main soil factor regulating R. nepalensis performance in sterilized soils. Our findings underline the importance of the soil microbes and nitrogen to R. nepalensis performance in natural ecosystems and will help to better predict plant population dynamics.
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Hou, Jianfeng, Fei Li, Zhihui Wang, Xuqing Li, Rui Cao et Wanqin Yang. « Dynamics of Dissolved Carbon in Subalpine Forest Streams ». Forests 13, no 5 (19 mai 2022) : 795. http://dx.doi.org/10.3390/f13050795.
Texte intégralRésumé :
Dissolved carbon (DC) in forest streams plays a crucial role in maintaining the structure and productivity of adjoining aquatic ecosystems as well as informing biogeochemical links between mountain forests and adjoining rivers. Nevertheless, the functions of forest stream DC dynamics are rarely incorporated into river management. To better understand the biogeochemical links between subalpine forests and adjoining streams, the seasonal dynamics of DC in 15 representative forest streams were investigated in a geographically fragile subalpine-gorge catchment in the upper reaches of the Yangtze River. Depending on stream characteristics and critical periods, the DC stocks in the streams ranged from 0.22 to 2.35 mg m−2 for total DC, from 0.10 to 1.66 mg m−2 for dissolved inorganic carbon (DIC), and from 0.12 to 1.27 mg m−2 for dissolved organic carbon (DOC). Moreover, the annual stocks of DC, DIC, and DOC were 1.01, 0.56, and 0.45 mg m−2, respectively. Correspondingly, the averaged export rates for DC, DIC, and DOC from the forest streams ranged from 0.27 to 1.98 mg s−1, from 0.24 to 1.48 mg s−1, and from 0.18 to 0.90 mg s−1, respectively, in the subalpine forest catchment. The annual export rates of total DC, DIC, and DOC were 1.06, 0.75, and 0.31 mg C s−1, respectively. In particular, the highest rates of export were 4.67, 3.53, and 1.34 mg s−1 for DC, DIC, and DOC, respectively, in the snowmelt period. The average ratios of DOC to DIC stock in the export water ranged from 0.23–2.41 for the 15 streams, and the average value was 0.85 during this one-year investigation. In addition, the maximum and minimum values of the DC stocks, their exports, and the DIC:DOC ratio were consistently observed during the snowmelt season and the late growing period. In summary, precipitation, temperature, water discharge rate, and sediment depth regulated the stocks and export rates of DC and its components. In general, forest streams are important links between the carbon biogeochemical cycle of subalpine forests and adjoining streams.
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Morris, Jesse L., R. Justin DeRose, Thomas Brussel, Simon Brewer, Andrea Brunelle et James N. Long. « Stable or seral ? Fire-driven alternative states in aspen forests of western North America ». Biology Letters 15, no 6 (juin 2019) : 20190011. http://dx.doi.org/10.1098/rsbl.2019.0011.
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As important centres for biological diversity, aspen forests are essential to the function and aesthetics of montane ecosystems in western North America. Aspen stands are maintained by a nuanced relationship with wildfire, although in recent decades aspen mortality has increased. The need to understand the baseline environmental conditions that favour aspen is clear; however, long-term fire history reconstructions are rare due to the scarcity of natural archives in dry montane settings. Here, we analyse a high-resolution lake sediment record from southwestern, Utah, USA to quantify the compositional and burning conditions that promote stable (or seral) aspen forests. Our results show that aspen presence is negatively correlated with subalpine fir and that severe fires tend to promote persistent and diverse aspen ecosystems over centennial timescales. This information improves our understanding of aspen disturbance ecology and identifies the circumstances where critical transitions in montane forests may occur.
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Calder, William John, Ivanka Stefanova et Bryan Shuman. « Climate–fire–vegetation interactions and the rise of novel landscape patterns in subalpine ecosystems, Colorado ». Journal of Ecology 107, no 4 (22 février 2019) : 1689–703. http://dx.doi.org/10.1111/1365-2745.13138.
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Liu, Shun, Da Luo, Hongguo Yang, Zuomin Shi, Qianli Liu, Li Zhang et Ying Kang. « Fine Root Dynamics in Three Forest Types with Different Origins in a Subalpine Region of the Eastern Qinghai-Tibetan Plateau ». Forests 9, no 9 (27 août 2018) : 517. http://dx.doi.org/10.3390/f9090517.
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Fine roots play a crucial role in plant survival potential and biogeochemical cycles of forest ecosystems. Subalpine areas of the Eastern Qinghai-Tibetan Plateau have experienced different forest re-establishment methods after clear-cutting primary forest. However, little is known about fine root dynamics of these forests originating from artificial, natural and their combined processes. Here, we determined fine root traits (biomass, production and turnover rate) of three subalpine forest types, i.e., Picea asperata Mast. plantation forest (artificial planting, PF), natural secondary forest (natural without assisted regeneration, NF) and P. asperata broadleaved mixed forest (natural regeneration after artificial planting, MF) composed of planted P. asperata and naturally regenerated native broadleaved species. At the soil depth of 0–30 cm, fine root biomass was the highest in PF and fine root production was the highest in NF, and both were the lowest in MF. Fine root dynamics of the three forest types tended to decrease with soil depth, with larger variations in PF. Fine root biomass and production were the highest in PF in 0–10 cm soil layer but were not significantly different among forest types in the lower soil layers. There were positive correlations between these parameters and aboveground biomass across forest types in soil layer of 0–10 cm, but not in the lower soil layers. Fine root turnover rate was generally higher in mixed forests than in monocultures at all soil depths. In conclusion, the natural regeneration procedure after clear-cutting in the subalpine region of western Sichuan seems to be superior from the perspective of fine root dynamics.
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Jabrayilov, Emil A. « Monitoring of Fragile Ecosystems with Spectral Indices Using Sentinel-2A MSI Data in Shahdagh National Park ». GEOGRAPHY, ENVIRONMENT, SUSTAINABILITY 15, no 1 (28 mars 2022) : 70–77. http://dx.doi.org/10.24057/2071-9388-2021-006.
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Studying ecosystems using remote sensing technologies is very relevant since it checks the accuracy of the results of modern research. This study aims to monitor environmental changes in ecosystems of the Shahdagh National Park and its surrounding areas in Azerbaijan using Sentinel 2A MSI data. The study aimed to examine and monitor changes in vegetation, water resources, and drought conditions of the study area in recent years. For analyzing and observing these ecosystems Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), and Normalized Difference Drought Index (NDDI) were calculated using multi-band methods. Obtained indices were compared and changes were investigated analyzing satellite-derived methods. For proper monitoring and assessment of relevant ecosystems, there had been determined 3,825 fishnet points for the study area. This made it possible to compare and coordinate the results of the indices more accurately. After linking fishnet points to raster indices, classification had been made for measuring ecosystems indicators. Vegetation assessments revealed a partial expansion of sparse vegetation or bare rocks, river valleys, as well as nival, subnival, and partial subalpine meadows from 15.1% to 18.1%. Another growth indicator is a significant increase of dense forest ecosystems from 2.3% to 9.2%. According to the results decreases are observed in sparse forests, arable lands, pastures, and shrubs, which are more sensitive to anthropogenic factors. Monitoring of the indices shows that low-humidity areas increase as droughts intensify, especially in plain areas. Finally, the study revealed that the introduction of a specially protected regime within the national park makes ecosystems more sustainable.
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Brovelli, M. A., M. Cannata et M. Rogora. « SIMILE, A GEOSPATIAL ENABLER OF THE MONITORING OF SUSTAINABLE DEVELOPMENT GOAL 6 (ENSURE AVAILABILITY AND SUSTAINABILITY OF WATER FOR ALL) ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4/W20 (15 novembre 2019) : 3–10. http://dx.doi.org/10.5194/isprs-archives-xlii-4-w20-3-2019.
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Abstract. The paper presents SIMILE (Italian acronym for “Integrated monitoring system for knowledge, protection and valorization of the subalpine lakes and their ecosystems), a cross-border Italian-Swiss project whose general objectives are the strengthening of the coordinated management of the water of the great subalpine lakes in the so-called Insubric region and the intensification of stakeholder participation in the processes of knowledge and monitoring of the water resource. The project fits the purpose of SDG 6 and involves administrations, monitoring agencies, universities and research centers, and citizens.SIMILE is a system where geospatial data, information, and techniques play a pivotal role. The system strongly benefits the information derived from the analysis of Sentinel 1 and Sentinel 3 imagery, in situ authoritative data, and user-contributed georeferenced data. A Business Intelligence (BI) platform, i.e. a web data-driven decision support system, will allow the integration, analysis, and synthesis of the information derived from the different types of data, heterogeneous in format, coordinate system, information content, and access method. The technologies that will be used are based on open software so as to guarantee the replicability and sustainability of the system.
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Cheng, Rui, Troy S. Magney, Debsunder Dutta, David R. Bowling, Barry A. Logan, Sean P. Burns, Peter D. Blanken et al. « Decomposing reflectance spectra to track gross primary production in a subalpine evergreen forest ». Biogeosciences 17, no 18 (15 septembre 2020) : 4523–44. http://dx.doi.org/10.5194/bg-17-4523-2020.
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Abstract. Photosynthesis by terrestrial plants represents the majority of CO2 uptake on Earth, yet it is difficult to measure directly from space. Estimation of gross primary production (GPP) from remote sensing indices represents a primary source of uncertainty, in particular for observing seasonal variations in evergreen forests. Recent vegetation remote sensing techniques have highlighted spectral regions sensitive to dynamic changes in leaf/needle carotenoid composition, showing promise for tracking seasonal changes in photosynthesis of evergreen forests. However, these have mostly been investigated with intermittent field campaigns or with narrow-band spectrometers in these ecosystems. To investigate this potential, we continuously measured vegetation reflectance (400–900 nm) using a canopy spectrometer system, PhotoSpec, mounted on top of an eddy-covariance flux tower in a subalpine evergreen forest at Niwot Ridge, Colorado, USA. We analyzed driving spectral components in the measured canopy reflectance using both statistical and process-based approaches. The decomposed spectral components co-varied with carotenoid content and GPP, supporting the interpretation of the photochemical reflectance index (PRI) and the chlorophyll/carotenoid index (CCI). Although the entire 400–900 nm range showed additional spectral changes near the red edge, it did not provide significant improvements in GPP predictions. We found little seasonal variation in both normalized difference vegetation index (NDVI) and the near-infrared vegetation index (NIRv) in this ecosystem. In addition, we quantitatively determined needle-scale chlorophyll-to-carotenoid ratios as well as anthocyanin contents using full-spectrum inversions, both of which were tightly correlated with seasonal GPP changes. Reconstructing GPP from vegetation reflectance using partial least-squares regression (PLSR) explained approximately 87 % of the variability in observed GPP. Our results linked the seasonal variation in reflectance to the pool size of photoprotective pigments, highlighting all spectral locations within 400–900 nm associated with GPP seasonality in evergreen forests.
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Oddi, Ludovica, Edoardo Cremonese, Lorenzo Ascari, Gianluca Filippa, Marta Galvagno, Davide Serafino et Umberto Morra di Cella. « Using UAV Imagery to Detect and Map Woody Species Encroachment in a Subalpine Grassland : Advantages and Limits ». Remote Sensing 13, no 7 (24 mars 2021) : 1239. http://dx.doi.org/10.3390/rs13071239.
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Woody species encroachment on grassland ecosystems is occurring worldwide with both negative and positive consequences for biodiversity conservation and ecosystem services. Remote sensing and image analysis represent useful tools for the monitoring of this process. In this paper, we aimed at evaluating quantitatively the potential of using high-resolution UAV imagery to monitor the encroachment process during its early development and at comparing the performance of manual and semi-automatic classification methods. The RGB images of an abandoned subalpine grassland on the Western Italian Alps were acquired by drone and then classified through manual photo-interpretation, with both pixel- and object-based semi-automatic models, using machine-learning algorithms. The classification techniques were applied at different resolution levels and tested for their accuracy against reference data including measurements of tree dimensions collected in the field. Results showed that the most accurate method was the photo-interpretation (≈99%), followed by the pixel-based approach (≈86%) that was faster than the manual technique and more accurate than the object-based one (≈78%). The dimensional threshold for juvenile tree detection was lower for the photo-interpretation but comparable to the pixel-based one. Therefore, for the encroachment mapping at its early stages, the pixel-based approach proved to be a promising and pragmatic choice.
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Tamahina, Aida, et Urfa Turan Ogly Turabov. « Production potential of the Kabardino-Balkarian Republic pasture ecosystems ». E3S Web of Conferences 262 (2021) : 03023. http://dx.doi.org/10.1051/e3sconf/202126203023.
Texte intégralRésumé :
The pasture digression of meadows followed by soil deflation is one of the pressing environmental problems. This problem is typical for mountain pastures that are constantly in economic circulation. The article presents the results of a geobotanical survey of the Zolsky pastures on the territory of the Kabardino-Balkarian Republic in 2018-2020. The results of a geobotanical survey show that the pasture phytocenoses are characterized by high floristic diversity due to the heterogeneity of edaphic and orographic factors. The flora of the pastures is represented by postwood moist sedgy-and-tussock-grass, mesophilic woodreed-and-agrostidinic grass, cereal forb, forbs cereal mesophilic and subalpine meadows, low sedgy meadow steppes. The average yield for the pasture period varies from 7.2 to 16.6 centners/ha of dry eaten mass. The consequence of prolonged pasturage and excessive pasture load was a decrease in alpha and beta diversity, the formation of low-productive secondary plant communities of non-food, poisonous and weed grasses, the destruction of sod and soil outcropping. Restoration of degraded pasture ecosystems is possible on the basis of ecological intensification, which provides for the regulation of pasture loads, adherence to grazing terms, phytomelioration using perennial grasses, and short-term isolation of pastures from grazing. This will prevent erosion processes, increase biodiversity, productivity, forage value of grass stand and stability of pasture ecosystems.
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Gracheva, Raisa, Elena Belonovskaya et Vera Vinogradova. « Mountain grassland ecosystems on abandoned agricultural terraces (Russia, North Caucasus) ». Hacquetia 17, no 1 (1 juin 2018) : 61–71. http://dx.doi.org/10.1515/hacq-2017-0010.
Texte intégralRésumé :
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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Bigler, Christof, et Thomas T. Veblen. « Changes in litter and dead wood loads following tree death beneath subalpine conifer species in northern Colorado ». Canadian Journal of Forest Research 41, no 2 (février 2011) : 331–40. http://dx.doi.org/10.1139/x10-217.
Texte intégralRésumé :
Litter and dead wood affect important processes in forest ecosystems such as nutrient and carbon cycling and are key influences on biodiversity and fire behavior. Increased tree mortality rates in western North America associated with climate trends and increased bark beetle activity highlight the need to better understand the dynamics of litter and dead wood following tree death. For eight old-growth stands in a subalpine forest landscape in northern Colorado (USA), we compared litter and dead wood loads beneath more than 200 dead and live Engelmann spruce (Picea engelmannii Parry ex Engelm.), subalpine fir (Abies lasiocarpa (Hook.) Nutt.), and lodgepole pine (Pinus contorta Douglas ex Loudon). The dynamics of litter and dead wood were analyzed using chronosequences of tree death dates over >100 years that we determined from tree rings. Immediately following tree death, high loads of litter accumulated, particularly for the biggest spruces, which accumulated 10 times more litter than live spruces (five times more for fir, two times more for pine). We estimated a higher decay rate of litter for spruce (half-life of four years) than for pine (15 years) and fir (19 years). The accumulation rates for dead wood following tree death were highly variable among trees, but maximum accumulation was attained during the first 50–60 years.
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Li, Han, Ting Du, Yulian Chen, Yu Zhang, Yulian Yang, Jiaping Yang, Qing Dong, Li Zhang et Qinggui Wu. « Effects of Forest Gaps on Abies faxoniana Rehd. Leaf Litter Mass Loss and Carbon Release along an Elevation Gradient in a Subalpine Forest ». Forests 13, no 8 (29 juillet 2022) : 1201. http://dx.doi.org/10.3390/f13081201.
Texte intégralRésumé :
Changes in the microenvironment induced by forest gaps may affect litter decomposition, yet it is unclear how the gap effects respond to altitudinal and seasonal differences. Here, a four-year litterbag decomposition experiment along an elevation gradient (3000, 3300, 3600 m) was conducted in an Abies faxoniana Rehd. subalpine forest of southwestern China, to assess the potential seasonal effects of forest gaps (large: ≈250 m2, middle: ≈125 m2, small: ≈40 m2 vs. closed canopy) on litter mass loss and carbon release at different elevations. We found that the A. faxoniana litter mass loss and carbon release reached 50~53 and 58~64% after four years of decomposition, respectively. Non-growing seasons (November to April) had a greater decline than the growing seasons (May to October). Litter in the forest gaps exhibited significantly higher mass loss than that under the closed canopy, and the decomposition constant (k) exhibited a gradually declining trend from large gaps, middle gaps, small gaps to closed canopy. Moreover, more significant differences of gap on both carbon content and release were observed at the 3600 m site than the other two elevations. Our findings indicate that (i) a rather high mass loss and carbon release during the decomposition of A. faxoniana litter was observed at high elevations of the subalpine forest subjected to low temperatures in the non-growing seasons and (ii) there were stimulative effects of forest gaps on litter mass loss and carbon release in early decomposition, especially in the non-growing seasons, driven by fewer freeze–thaw cycles when compared to the closed canopy, which diminished at the end of the experiment. The results will provide crucial ecological data for further understanding how opening gaps as a main regeneration method would induce changes in carbon cycling in subalpine forest ecosystems.
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Zeidler, Miroslav, Martin Duchoslav et Marek Banaš. « Effect of altered snow conditions on decomposition in three subalpine plant communities ». Open Life Sciences 9, no 8 (1 août 2014) : 811–22. http://dx.doi.org/10.2478/s11535-014-0312-3.
Texte intégralRésumé :
AbstractSnow cover and its spatio-temporal changes play a crucial role in the ecological functioning of mountains. Some human activities affecting snow properties may cause shifts in the biotic components of ecosystems, including decomposition. However, these activities remain poorly understood in subalpine environments. We explored the effect of human-modified snow conditions on cellulose decomposition in three vegetation types. Snow density, soil temperature, and the decomposition of cellulose were studied in Athyrium, Calamagrostis, and Vaccinium vegetation types, comparing stands intersected by groomed ski slope and natural (outside the ski slope) stands. Increased snow density caused the deterioration of snow insulation and decreased the soil temperature inside the ski slope only slightly in comparison with that outside the ski slope in all vegetation types studied. The decomposition was apparently lower in Athyrium vegetation relative to the other vegetation types and strongly (Athyrium vegetation) to weakly lower (other vegetation types) in groomed than in ungroomed stands. Wintertime, including the melting period, was decisive for overall decomposition. Our results suggest that differences in decomposition are influenced by ski slope operations and vegetation type. Alterations in snow conditions appeared to be subtle and long-term but with important consequences for conservation management.
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Barrett, SW. « Fire Regimes on Andesitic Mountain Terrain in Northeastern Yellowstone-National-Park, Wyoming ». International Journal of Wildland Fire 4, no 2 (1994) : 65. http://dx.doi.org/10.1071/wf9940065.
Texte intégralRésumé :
A fire history investigation was conducted for three forest community types in the Absaroka Mountains of Yellowstone National Park, Wyoming. Master fire chronologies were based on fire-initiated age classes and tree fire scars. The area's major forest type, lodgepole pine (Pinus contorta Dougl. var. latifolia) ecosystems, revealed a predominant pattern of stand replacing fires with a 200 year mean interval-nearly half the length estimated in previous studies of lodgepole pine on less productive subalpine plateaus in YNP. High elevation whitebark pine (P. albicaulis Engelm.) forests had primarily stand replacing fires with >350 year mean intervals, but some stands near timberline also occasionally experienced mixed severity- or non-lethal underburns. Before nearly a century of effective fire suppression in Yellowstone's northern range, lower elevation Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco.) communities adjacent to Artemesia tridentata (Nutt.) grasslands experienced primarily non-lethal underburns at 30 year mean intervals. While short interval fire regimes have been altered by longterm fire suppression, fire exclusion apparently had only limited influence on the area's infrequently burned ecosystems prior to widespread stand replacement burning in 1988.