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1.
Recent work in seasonally snow covered ecosystems has identifiedthawed soil and high levels of heterotrophic activity throughout the winterunder consistent snow cover. We performed measurements during the winter of1994 to determine how the depth and timing of seasonal snow cover affectsoil microbial populations, surface water NO loss during snowmelt, and plant Navailability early in the growing season. Soil under early accumulating,consistent snow cover remained thawed during most of the winter and bothmicrobial biomass and soil inorganic N pools gradually increased under thesnowpack. At the initiation of snowmelt, microbial biomass N pools increasedfrom 3.0 to 5.9 g n m-2,concurrent with a decrease in soil inorganic N pools. During the latterstages of snowmelt, microbial biomass N pools decreased sharply without aconcurrent increase in inorganic N pools or significant leaching losses. Incontrast, soil under inconsistent snow cover remained frozen during most ofthe winter. During snowmelt, microbial biomass initially increased from 1.7to 3.1 g N m-2 and thendecreased as sites became snow-free. In contrast to smaller pool sizes,NO export during snowmeltfrom the inconsistent snow cover sites of 1.14 (±0.511) g N m-2 was significantly greater (p< 0.001) than the 0.27 (±0.16) g N m-2 exported from sites with consistent snowcover. These data suggest that microbial biomass in consistentlysnow-covered soil provides a significant buffer limiting the export ofinorganic N to surface water during snowmelt. However, this buffer is verysensitive to changes in snowpack regime. Therefore, interannual variabilityin the timing and depth of snowpack accumulation may explain the year toyear variability in inorganic N concentrations in surface water theseecosystems. 相似文献
2.
Mohammad Bagher Erfanian Hamid Ejtehadi Jamil Vaezi Hamid Moazzeni Farshid Memariani Mohammad Firouz‐Jahantigh 《Ecology and evolution》2019,9(14):8193-8200
It is well‐known that pistes have adverse effects on alpine ecosystems. Previous studies urged that pistes should be installed and managed in the ways to minimize negative impacts on natural habitats. However, the impacts of this type of management on the plant communities are not widely studied. The aim of this study was to examine species composition and biodiversity changes in an environmentally friendly managed piste in northeast Iran. This piste has been established in a previously degraded alpine landscape. For the vegetation survey, we sampled 44 within and 28 off‐piste plots. Except for the piste management, other environmental factors were similar between the piste and off‐piste plots. Dominant species were determined, and variation in community composition of the two areas was visualized. Also, native species, phylogenetic, and functional Hill diversity of the two areas were compared. The results showed that there was a moderate differentiation in the species composition of the piste and off‐piste. Two palatable species (i.e., Bupleurum falcatum and Melica persica) were dominant in the piste and were not recorded in the off‐piste. The diversity calculations results showed that the species diversity of the piste was higher than that of the off‐piste. Phylogenetic diversity at the level of frequent and dominant plants showed a similar result. The piste had a higher functional diversity in terms of functional richness, and functional diversity of frequent and dominant plants. Our findings imply, after 10 years, species, phylogenetic, and functional diversity of the piste is significantly improved. Environmentally friendly piste management (EFPM) induced species composition change that led to emerging species that were absent in the off‐piste. We can conclude that EFPM led to restoration of a degraded landscape. Long‐term impacts of EFPM are still unknown, therefore, caution should be undertaken regarding the installation of new environmentally friendly pistes in other areas. 相似文献
3.
长白山苔原是我国乃至欧亚大陆东部独有的高山苔原,根据前人调查植被以灌木苔原为主要类型。在全球变暖背景下,近30年来,长白山岳桦林下的草本植物侵入苔原带,原生灌木苔原分化为灌木苔原、灌草苔原和草本苔原,形成了灌木、灌草混合和草本3种不同类型的凋落物,凋落物数量和质量发生显著改变。与此同时长白山苔原氮沉降量也在逐年增加,导致了土壤中氮的累积,势必影响凋落物的分解。凋落物作为连接植物和土壤的纽带,其分解过程中碳（C）、氮（N）、磷（P）等化学组分和化学计量比的变化直接和间接影响着土壤养分有效性和植物养分利用策略。为揭示氮沉降增加对长白山苔原带不同类型凋落物化学组分及生态化学计量特征早期变化的影响,开展了为期8个月的模拟氮沉降室内凋落物分解实验。在苔原带采集灌木优势种牛皮杜鹃和草本优势种小叶章的凋落物带回实验室,模拟灌木牛皮杜鹃群落、灌草混合的牛皮杜鹃-小叶章群落和草本小叶章群落的3种不同类型凋落物,设置三个施氮处理：对照（CK,0 g N m-2 a-1）、低氮（LN,10 g N m-2 a-1）、高氮（HN,20 g N m-2 a-1）。研究表明：（1）不施氮处理时,3种凋落物的C、P均呈释放状态,木质素（Li）呈先累积再略有降解趋势;牛皮杜鹃凋落物的N元素富集而其余两种凋落物N元素呈释放状态;灌草混合和草本凋落物比原生的灌木凋落物C和N元素释放快、Li累积少;而灌木凋落物的P释放略快于灌草和草本凋落物。3种植被类型凋落物的C/N、C/P、Li/N大小表现为：牛皮杜鹃凋落物>牛皮杜鹃-小叶章混生群落凋落物>小叶章凋落物;N/P表现为：小叶章凋落物>牛皮杜鹃凋落物>牛皮杜鹃-小叶章混生群落凋落物。（2）氮沉降促进3种类型凋落物分解过程中C、N和P化学组分的释放,且氮浓度越高促进作用越显著。在牛皮杜鹃凋落物分解过程中,氮素添加到达某一阈值后,其C/N、C/P、N/P、Li/N的降幅最大,后续若再增加氮素,其对化学计量比的影响均会减弱;本实验中的氮素添加量增加促进了小叶章凋落物的C/N、Li/N下降。（3）草本植物入侵引起凋落物类型的变化带来凋落物分解加快,将导致长白山苔原带养分循环的变化;氮沉降增加对小叶章凋落物化学组分的释放及C/N、Li/N的下降更为促进,小叶章凋落物内难分解化合物减少,分解受到促进。高氮沉降加快了小叶章凋落物与土壤、草本植物之间的养分循环。因此,随着未来苔原带氮沉降量的增加,将更有利于小叶章在与牛皮杜鹃的竞争中获胜,使苔原带呈现草甸化趋势。 相似文献
4.
A.E. West P.D. Brooks M.C. Fisk L.K. Smith E.A. Holland C.H. Jaeger III S. Babcock R.S. Lai S.K. Schmidt 《Biogeochemistry》1999,45(3):243-264
We measured CH4 fluxes from three major plant communities characteristic of alpine tundra in the Colorado Front Range. Plant communities in this ecosystem are determined by soil moisture regimes induced by winter snowpack distribution. Spatial patterns of CH4 flux during the snow-free season corresponded roughly with these plant communities. InCarex-dominated meadows, which receive the most moisture from snowmelt, net CH4 production occurred. However, CH4 production in oneCarex site (seasonal mean=+8.45 mg CH4 m–2 d–1) was significantly larger than in the otherCarex sites (seasonal means=–0.06 and +0.05 mg CH4 m–2 d–1). This high CH4 flux may have resulted from shallower snowpack during the winter. InAcomastylis meadows, which have an intermediate moisture regime, CH4 oxidation dominated (seasonal mean=–0.43 mg CH4 m–2 d–1). In the windsweptKobresia meadow plant community, which receive the least amount of moisture from snowmelt, only CH4 oxidation was observed (seasonal mean=–0.77 mg CH4 m–2 d–1). Methane fluxes correlated with a different set of environmental factors within each plant community. In theCarex plant community, CH4 emission was limited by soil temperature. In theAcomastylis meadows, CH4 oxidation rates correlated positively with soil temperature and negatively with soil moisture. In theKobresia community, CH4 oxidation was stimulated by precipitation. Thus, both snow-free season CH4 fluxes and the controls on those CH4 fluxes were related to the plant communities determined by winter snowpack. 相似文献
5.
通过多次对长白山高山冻原的实地考察,统计得到冻原种子植物共计34科、94属、146种,有6种属的分布区类型(包括3个变型),北温带分布类型最多,占总属数的68.09%。在整个冻原上,草本有125种,占总数的85.62%,其中多年生草本124种。高山冻原植物中具有多种生态,生理适应方式,低矮平卧状植株、极矮小草本、密集丛生是植物的重要适应方式,细长密集须根是冻原上主要的适应方式,占植物总数的54.94%。果实中干果共计137种,其中蒴果56种。由于高山冻原上生态环境十分残酷,极易受人为因素的影响。 相似文献
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Katharine N. Suding Emily C. Farrer Andrew J. King Lara Kueppers Marko J. Spasojevic 《Plant Ecology & Diversity》2015,8(5-6):713-725
Background: High-elevation mountain systems may be particularly responsive to climate change.Aims: Here we investigate how changes along elevation gradients in mountain systems can aid in predicting vegetation distributional changes in time, focusing on how changing climatic controls affect meso-scale transitions at the lower and upper boundaries of alpine vegetation (with forest and subnival zones, respectively) as well as micro-scale transitions among plant communities within the alpine belt. We focus on climate-related drivers, particularly in relation to climate change, but also consider how species interactions, dispersal and responses to disturbance may influence plant responses to these abiotic drivers.Results: Empirical observations and experimental studies indicate that changing climatic controls influence both meso-scale transitions at the upper and lower boundaries of alpine vegetation and micro-scale transitions among plant communities within tundra. Micro-scale heterogeneity appears to buffer response in many cases, while interactions between climate and other changes may often accelerate change.Conclusions: Interactions with microtopography and larger edaphic gradients have the capacity to both facilitate rapid changes and reinforce stability, and that these interactions will affect the responsiveness of vegetation to climate change at different spatial scales. 相似文献
7.
高寒草甸及湿地是青藏高原上最为重要的生态系统,它的状况直接关系到我国江河源头的蓄水量.也关系到我国中部和东部广大地区的工农业及人民生活用水．因此对青藏高原高寒草甸与湿地的保护具有重要的现实意义。本研究对青藏高原东北缘黄河源头地区甘南藏族自治州的玛曲县高寒草甸及湿地进行调查,揭示了该地区的植被生物多样性情况与组成结构,利用解析层次方法分析了高寒草甸及湿地的退化原因及恢复手段,同时还从集合种群竞争原理出发对该地区植被生物多样性的维持机理进行了讨论。结果显示出两个现存的主要矛盾：在生物多样性保护与高寒草甸质量提高方面存在矛盾;在地区发展与高寒草甸质量提高方面也存在矛盾。前者表明为了提高物种多样性,必须存在一定干扰．包括人为干扰与自然生态系统干扰,这些干扰会在高寒草甸中形成一定数量的空斑块．这些空斑块为先锋种的繁殖提供了暂时的场所从而使多样性得到提高与维持。但由于先锋种普遍为杂草类而非优良牧草．因此这种多样性维持只能以牺牲草甸质量为代价。第二个矛盾说明为了提高当地经济与社会发展．必然会增加人为干扰,而这些干扰会首先对优良牧草造成不利,从而使杂草比例增加并进一步抑制牧场质量从而限制地区以畜牧业为主的经济发展。 相似文献
8.
Analysis of nitrogen saturation potential in Rocky Mountain tundra and forest: implications for aquatic systems 总被引：2，自引：1，他引：2
Jill S. Baron Dennis S. Ojima Elisabeth A. Holland William J. Parton 《Biogeochemistry》1994,27(1):61-82
We employed grass and forest versions of the CENTURY model under a range of N deposition values (0.02–1.60 g N m–2 y–1) to explore the possibility that high observed lake and stream N was due to terrestrial N saturation of alpine tundra and subalpine forest in Loch Vale Watershed, Rocky Mountain National Park, Colorado. Model results suggest that N is limiting to subalpine forest productivity, but that excess leachate from alpine tundra is sufficient to account for the current observed stream N. Tundra leachate, combined with N leached from exposed rock surfaces, produce high N loads in aquatic ecosystems above treeline in the Colorado Front Range. A combination of terrestrial leaching, large N inputs from snowmelt, high watershed gradients, rapid hydrologic flushing and lake turnover times, and possibly other nutrient limitations of aquatic organisms constrain high elevation lakes and streams from assimilating even small increases in atmospheric N. CENTURY model simulations further suggest that, while increased N deposition will worsen the situation, nitrogen saturation is an ongoing phenomenon. 相似文献
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对长白山高山冻原生态系统中 3种养分 (N、P和 S)在植被 -凋落物 -土壤中的空间分布规律进行了研究。结果表明 :(1)在长白山高山冻原植被亚系统中 ,3种养分总含量分布规律是石质高山冻原 (ST) >典型高山冻原 (TT) >沼泽高山冻原 (WT) >草甸高山冻原 (MT) >石海高山冻原 (RT) ;3种养分积累总量为 72 .4 6 kg· hm- 2 ,其中 N、P和 S分别是 4 8.5 5 kg· hm- 2 ,10 .33kg· hm- 2 和 13.6 1kg· hm- 2 ;生物量与养分积累分布规律是 WT>TT>MT>ST>RT。 (2 )在长白山高山冻原凋落物亚系统中 ,平均凋落物量是 1.96 kg· hm- 2 ;3种养分积累总量为 :82 .5 kg· hm- 2 ,其中 N、P和 S分别是 4 6 .2 8kg· hm- 2 ,2 1.14 kg· hm- 2 和 15 .0 8kg· hm- 2 ;养分积累总量分布规律是 TT>WT>RT>MT>ST。 (3)长白山高山冻原土壤 (0～ 2 0cm)亚系统中 ,养分积累总量为 39.6 t· hm- 2 ,其中 N、P和 S分别是 2 3.76 t· hm- 2 ,5 .86 t· hm- 2和 9.98t· hm- 2。 4 )在长白山高山冻原生态系统中 ,3种养分总积累量为 4 0 6 4 4 .98kg· hm- 2 ,其中 N、P和 S分别是 2 4 734.85 kg· hm- 2 ,10 0 18.7kg·hm- 2 和 5 891.4 3kg· hm- 2 ,土壤库是长白山高山冻原的主要养分储存库 相似文献
11.
研究了长白山高山带雪斑牛皮杜鹃(Rhododendron aureum)群落的生产力特征及其同微生境条件的关系,以阐明寒冷条件下碳蓄积特征.结合土壤温度连续观测,测定了雪斑不同部位的群落生产力以及土壤养分特征.牛皮杜鹃群落的积雪时间超过240d,土壤温度在-1～0℃的时间长达150d,是非雪斑地段的3倍以上.尽管雪斑的热量条件不如周围优越,但是群落生产力相对高出很多.雪斑中心的牛皮杜鹃群落近3a的现存量(1707g/m2)是边缘无雪地段(288g/ m2)的6倍.雪斑中心的土壤养分水平比周围高,雪斑同时为植物提供了极端低温条件下的避难场所.苔原生态系统生产力的维持依赖于寒冷季节的相对温暖环境,而不是生长季节的热量水平. 相似文献
12.
Jack M. Averett Robert A. Klips Lucas E. Nave Serita D. Frey Peter S. Curtis 《Restoration Ecology》2004,12(4):568-574
Restoration of tallgrass prairie on former agricultural land is often impeded by failure to establish a diverse native species assemblage and by difficulties with nonprairie, exotic species. High levels of available soil nitrogen (N) on such sites may favor fast‐growing exotics at the expense of more slowly growing prairie species characteristic of low‐N soils. We tested whether reducing N availability through soil carbon (C) amendments could be a useful tool in facilitating successful tallgrass prairie restoration. We added 6 kg/m2 hardwood sawdust to experimental plots on an abandoned agricultural field in the Sandusky Plains of central Ohio, United States, increasing soil C by 67% in the upper 15 cm. This C amendment caused a 94% reduction in annual net N mineralization and a 27% increase in soil moisture but had no effect on total N or pH. Overall, plant mass after one growing season was reduced by 64% on amended compared with unamended soil, but this effect was less for prairie forbs (?34%) than for prairie grasses (?67%) or exotics (?62%). After the second growing season, only exotics responded significantly to the soil C amendment, with a 40% reduction in mass. The N concentration of green‐leaf tissue and of senescent leaf litter was also reduced by the soil C treatment in most cases. We conclude that soil C amendment imparts several immediate benefits for tallgrass prairie restoration––notably reduced N availability, slower plant growth, and lower competition from exotic species. 相似文献
13.
Climate change is expected to increase woody vegetation abundance in the Arctic, yet the magnitude, spatial pattern and pathways of change remain uncertain. We compared historical orthophotos photos (1952 and 1979) with high-resolution satellite imagery (2015) to examine six decades of change in abundance of white spruce Picea glauca and tall shrubs (Salix spp., Alnus spp.) near the Agashashok River in northwest Alaska. We established ~3000 random points within our ~5500 ha study area for classification into nine cover types. To examine physiographic controls on tree abundance, we fit multinomial log-linear models with predictors derived from a digital elevation model and with arctic tundra, alpine tundra and ‘tree’ as levels of a categorical response variable. Between 1952 and 2015, points classified as arctic and alpine tundra decreased by 31% and 15%, respectively. Meanwhile, tall shrubs increased by 86%, trees mixed with tall shrubs increased by 385% and forest increased by 84%. Tundra with tall shrubs rarely transitioned to forest. The best multinomial model explained 71% of variation in cover and included elevation, slope and an interaction between slope and ‘northness’. Treeline was defined as the elevation where the probability of tree presence equaled that of tundra. Mean treeline elevation in 2015 was 202 m, corresponding with a June–August mean air temperature > 11°C, which is > 4°C warmer than the 6–7°C isotherm associated with global treeline elevations. Our results show dramatic increases in the abundance of trees and tall shrubs, question the universality of air temperature as a predictor of treeline elevation and suggest two mutually exclusive pathways of vegetation change, because tundra that gained tall shrubs rarely transitioned to forest. Conversion of tundra to tall shrubs and forest has important and potentially contrasting implications for carbon cycling, surface energy exchange and wildlife habitat in the Arctic. 相似文献
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研究了长白山高山冻原生态系统中凋落物量及其养分空间分布特征 ,并对凋落物在养分生物循环中的功能进行了讨论。结果表明 :长白山高山冻原植被凋落物量为 1.378～ 2 .4 76 t/hm2 ,通过对不同海拔凋落物量的数量特征进行分析 ,海拔是影响长白山高山冻原植被凋落物量的主要因子。长白山高山冻原生态系统凋落物中 S、N和 P含量分别为 0 .14 % ,0 .4 9%和0 .2 1% ;3种营养元素在凋落物中积累量为 81.99kg/hm2 ,其中 S、N和 P积累量分别是 15 .0 4 kg/hm2 ,4 5 .93kg/hm2 和2 1.0 2 kg/hm2 。长白山高山冻原生态系统中 5种植被型 (FA,L A,TA,MA和 SA)年归还量依次为 0 .72 ,1.35 ,14 .6 5 ,10 .88和 11.91kg/(hm2· a) ;平均归还率依次 0 .33,0 .4 2 ,0 .39,0 .39和 0 .4 8。典型高山冻原植被型的归还量最大 ,而归还率却较低。长白山高山冻原生态系统内 S、N和 P的利用效率分别是 7.14、2 .0 4和 4 .76。在整个长白山高山冻原生态系统中 S和P的利用效率大于 N的利用效率 相似文献
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Plant species can influence nitrogen (N) cycling indirectly through the feedbacks of litter quality and quantity on soil
N transformation rates. The goal of this research was to focus on small-scale (within-community) variation in soil N cycling
associated with two community dominants of the moist meadow alpine tundra. Within this community, the small-scale patchiness
of the two most abundant species (Acomastylis rossii and Deschampsia caespitosa) provides natural variation in species cover within a relatively similar microclimate, thus enabling estimation of the effects
of plant species on soil N transformation rates. Monthly rates of soil N transformations were dependent on small-scale variation
in both soil microclimate and species cover. The relative importance of species cover compared with soil microclimate increased
for months 2 and 3 of the 3-month growing season. Growing-season net N mineralization rates were over ten times greater and
nitrification rates were four times greater in Deschampsia patches than in Acomastylis patches. Variability in litter quality [carbon:nitrogen (C:N) and phenolic:N], litter quantity (aboveground and fine-root
production), and soil quality (C:N) was associated with three principal components. Variability between the species in litter
quality and fine-root production explained 31% of the variation in net N mineralization rates and 36% of net nitrification
rates. Site variability across the landscape in aboveground production and soil C:N explained 33% of the variation in net
N mineralization rates and 21% of net nitrification rates. Within the moist meadow community, the high spatial variability
in soil N transformation rates was associated with differences in the dominant species' litter quality and fine-root production.
Deschampsia-dominated patches consistently had greater soil N transformation rates than did Acomastylis-dominated patches across the landscape, despite site variability in soil moisture, soil C:N, and aboveground production.
Plant species appear to be an important control of soil N transformation in the alpine tundra, and consequently may influence
plant community structure and ecosystem function. 相似文献
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长白山高山冻原植物群落的生态优势度 总被引：14，自引：1，他引：14
生态优势度(ecological dominance)或称集中优势度(dominance concentration),是综合群落中各个种群的重要性,反映各种群优势状况的指标,是群落结构的一个度量值。 相似文献
20.
通过野外调查、文献查阅、专家咨询及市场调查等手段获得长白山高山苔原带植物生存状况、分布数量的基本数据。在查阅文献的基础上,借助专家咨询构建了长白山高山苔原带植物受危等级、优先保护定量评估体系。该体系包含3个子系统,每个子系统下设不同指标共计12个。通过专家咨询法和层次分析法相结合的方法确定各子系统及各指标的权重。共评估植物94种,其中极危种3种,濒危种6种,易危种22种,近危种42种,无危种21种;在保护的缓急程度上,属于特级保护的有5种,一级保护的有6种,二级保护的有34种,三级保护的有30种,暂缓保护的有19种。评估结果与以往的红色名录进行了比较,一些从未列入红色目录的种类在本研究结果中有所体现。相反,有些曾被列入红色名录的物种在本次评估中被列为\"无危\"。对评估结果与以往红色名录之间产生差异种类及原因进行了讨论。 相似文献