Winter forest soil respiration controlled by climate and microbial community composition

Most terrestrial carbon sequestration at mid-latitudes in the Northern Hemisphere occurs in seasonal, montane forest ecosystems. Winter respiratory carbon dioxide losses from these ecosystems are high, and over half of the carbon assimilated by photosynthesis in the summer can be lost the following winter. The amount of winter carbon dioxide loss is potentially susceptible to changes in the depth of the snowpack; a shallower snowpack has less insulation potential, causing colder soil temperatures and potentially lower soil respiration rates. Recent climate analyses have shown widespread declines in the winter snowpack of mountain ecosystems in the western USA and Europe that are coupled to positive temperature anomalies. Here we study the effect of changes in snow cover on soil carbon cycling within the context of natural climate variation. We use a six-year record of net ecosystem carbon dioxide exchange in a subalpine forest to show that years with a reduced winter snowpack are accompanied by significantly lower rates of soil respiration. Furthermore, we show that the cause of the high sensitivity of soil respiration rate to changes in snow depth is a unique soil microbial community that exhibits exponential growth and high rates of substrate utilization at the cold temperatures that exist beneath the snow. Our observations suggest that a warmer climate may change soil carbon sequestration rates in forest ecosystems owing to changes in the depth of the insulating snow cover.     

Are lemmings prey or predators?

Large oscillations in the populations of Norwegian lemmings have mystified both professional ecologists and lay public. Ecologists suspect that these oscillations are driven by a trophic mechanism: either an interaction between lemmings and their food supply, or an interaction between lemmings and their predators. If lemming cycles are indeed driven by a trophic interaction, can we tell whether lemmings act as the resource ('prey') or the consumer ('predator')? In trophic interaction models, peaks of resource density generally have a blunt, rounded shape, whereas peaks of consumer density are sharp and angular. Here we have applied several statistical tests to three lemming datasets and contrasted them with comparable data for cyclic voles. We find that vole peaks are blunt, consistent with their cycles being driven by the interaction with predators. In contrast, the shape of lemming peaks is consistent with the hypothesis that lemmings are functional predators, that is, their cycles are driven by their interaction with food plants. Our findings suggest that a single mechanism, such as interaction between rodents and predators, is unlikely to provide the 'universal' explanation of all cyclic rodent dynamics.     

Stability of alpine meadow ecosystem on the Qinghai- Tibetan Plateau

THE QINGHAI-TIBETAN PLATEAU PLAYS AN IMPORTANT ROLE IN THE ATMOSPHERIC CIRCULATION AND REGIONAL MONSOON CLIMATE, WHICH HAS GREAT INFLUENCE ON THE REGIONAL AND GLOBAL CLIMATE. THUS, THE CHANGE OF THE QINGHAI-TIBETAN PLATEAU ECOSYSTEM IS EXPECTED TO AFFECT …     

Single-species models for many-species food webs

Most species live in species-rich food webs; yet, for a century, most mathematical models for population dynamics have included only one or two species. We ask whether such models are relevant to the real world. Two-species population models of an interacting consumer and resource collapse to one-species dynamics when recruitment to the resource population is unrelated to resource abundance, thereby weakening the coupling between consumer and resource. We predict that, in nature, generalist consumers that feed on many species should similarly show one-species dynamics. We test this prediction using cyclic populations, in which it is easier to infer underlying mechanisms, and which are widespread in nature. Here we show that one-species cycles can be distinguished from consumer resource cycles by their periods. We then analyse a large number of time series from cyclic populations in nature and show that almost all cycling, generalist consumers examined have periods that are consistent with one-species dynamics. Thus generalist consumers indeed behave as if they were one-species populations, and a one-species model is a valid representation for generalist population dynamics in many-species food webs.     

青藏铁路工程对高寒草地生态系统的影响

分析了青藏铁路冻土区段高寒生态系统主要分布类型及其变化背景，利用对青藏公路工程的类比调查数据，研究了不同高寒生态系统对工程扰动的抗干扰能力和受损后的自然恢复能力，以及不同生态系统与冻土环境的相互关系。综合考虑干扰场地土壤环境，冻土条件以及不同生态系统对干扰的抵抗与恢复能力等要素，提出了评价青藏铁路对生态环境影响的综合干扰度方法和定量评价模型，基于未来不同气候演变情境及其与人类工程活动耦合下冻土环境变化及其对高寒生态系统的影响。结合青藏铁路施工方案，定量评价了青藏铁路工程对高寒生态系统的可能影响。结果表明：大部分严重干扰施工地带对高寒草甸草地只有中等程度影响，影响区高寒草地植被覆盖度将维持在50％以上，高寒草原区重工程扰动地带除了局部有明显影响外，大部分地区只有中等至轻度影响，而中度与轻度工程扰动区域，工程对高寒生态系统的影响轻微。     

高山积雪：母亲河之源——积雪分布时空演化的多物理过程、多尺度研究

 雪是地球上最为活跃的自然要素之一,是组成极地冰盖和高山冰川的重要物质来源,同时也是地表径流的主要补给。积雪的时空分布和演变深刻影响着全球的水文循环、生态系统、气候演化以及其他自然过程,在高寒山区水文过程中扮演着重要的角色。高山积雪与冰川融水是黄河源头水源补给的主要形式,因此亟需开展黄河源区积雪水资源综合科学研究,在准确评估黄河源区水资源现状及其变化规律和发展趋势的基础上提出科学合理的保护和开发黄河水资源的策略。积雪分布研究涉及大气湍流与颗粒相互作用等具有挑战性的科学前沿及热点问题,以及多场耦合、多尺度等科学共性问题,还涉及力学学科与地理学、大气物理、气候变化等相关学科的交叉问题。目前对积雪分布的研究手段包括野外观测、遥感反演和基于动力学过程的模式研究。鉴于前两种手段的局限性,开展多物理过程、多尺度、多场耦合的积雪分布时空演化模拟已成为积雪水资源研究的重要手段之一。介绍了积雪分布研究现状及进展,指出了面临的挑战以及下一步研究方向。     

Potential impacts of a warming climate on water availability in snow-dominated regions

All currently available climate models predict a near-surface warming trend under the influence of rising levels of greenhouse gases in the atmosphere. In addition to the direct effects on climate--for example, on the frequency of heatwaves--this increase in surface temperatures has important consequences for the hydrological cycle, particularly in regions where water supply is currently dominated by melting snow or ice. In a warmer world, less winter precipitation falls as snow and the melting of winter snow occurs earlier in spring. Even without any changes in precipitation intensity, both of these effects lead to a shift in peak river runoff to winter and early spring, away from summer and autumn when demand is highest. Where storage capacities are not sufficient, much of the winter runoff will immediately be lost to the oceans. With more than one-sixth of the Earth's population relying on glaciers and seasonal snow packs for their water supply, the consequences of these hydrological changes for future water availability--predicted with high confidence and already diagnosed in some regions--are likely to be severe.     

Dietary overlap of snow leopard and other carnivores in the Pamirs of Northwestern China

Information about competition between carnivore species for food within high altitude regions is limited.Data collected from the Taxkorgan Nature Reserve,China revealed important interactions between snow leopard(Panthera uncia),grey wolf(Canis lupus),red fox(Vulpes vulpes)and their prey species,including domestic livestock.Sixty-four line transects were conducted in order to identify field signs of habitat occupancy and collect scats for diet analysis.High dietary overlap was observed between all three carnivore species:snow leopard and red fox(Pianka’s index=0.96),red fox and grey wolf(Pianka’s index=0.90),snow leopard and grey wolf(Pianka’s index=0.87).Snow leopard and grey wolf showed significant predation on livestock(36.8%for snow leopard and 29.4%for grey wolf in diet composition).As a pioneering exploration of the endangered snow leopard and its relationship with other species within the alpine ecosystem under livestock grazing pressure,this study contributes a greater understanding of the relationship within carnivore guild in the Pamirs whilst providing implications for conservation planning and project implementation activities in China.     

短效不育剂对成年害鼠控制的建模与分析

建立短效不育剂控制下害鼠种群的动态模型,模型中害鼠分为成体和幼体,不育控制只对成体起作用.对模型的性态以及不育率、恢复率等参数对种群发展的影响进行分析.结果表明:较高的不育率会达到更好的控制效果,使种群规模较小,甚至灭绝;不育剂的短效性限制了不育剂在控制害鼠上的作用,也限制了控制的效果;不育控制不改变种群的稳定年龄分布.     

高寒草甸生态系统中轮牧实验的系统分析

采用高寒草甸放牧生态统的分室模型对高寒草甸生态系统轮牧实验进行系统分析。结果表明：１）轮牧并不一定能节约牧草。它可以在有限的草甸上控制绵羊生长速度或牧草消耗速度；使绵羊顺利地渡过冬春季，２）绵羊体重达到最大值的时间与放牧强度成反比。     

Spatiotemporal variation in alpine grassland phenology in the Qinghai-Tibetan Plateau from 1999 to 2009

Plant phenology is the most salient and sensitive indicator of terrestrial ecosystem response to climate change.Studying its change is significantly important in understanding and predicting impressively changes in terrestrial ecosystem.Based on NDVI from SPOT VGT,this paper analyzed the spatiotemporal changes in alpine grassland phenology in Qinghai-Tibetan Plateau from 1999 to 2009.The results are enumerated as follows:(1) The spatial distribution of the average alpine grassland phenology from 1999 to 2009 is closely related to water and heat conditions.Accompanying the deterioration in heat and water conditions from southeast to northwest,the start of growth season(SOG) was delayed gradually,the end of growth season(EOG) advanced slowly,and the length of growth season(LOG) shortened gradually.Elevation played an important role in the regional differentiation of phenology,but a dividing line of approximately 3500 m existed.Below this line,the phenology fluctuated irregularly with altitude change,whereas above the line,the phenology is closely related to altitude change.(2) From 1999 to 2009,SOG of the alpine grassland came earlier by six days per decade(R2=0.281,P=0.093),EOG was late by two days per decade(R2=0.031,P=0.605),and LOG lengthened by eight days per decade(R2=0.479,P=0.018).The early SOG,the late EOG,and the extended LOG mainly occurred at the center and east of the Plateau.SOG in most of the Plateau advanced significantly,especially in the eastern Plateau.(3) The inter-annual phenology changes of the alpine grassland in the Qinghai-Tibetan Plateau exhibited significant differentiation at different elevation and natural zones.The inter-annual changes at high altitude were more complicated than that at low altitude.The most significant phenology changes were found in the eastern Qinghai-Qilian montane steppe zone,and non-significant changes occurred in the Southern Tibet montane shrub-steppe zone.     

保定城区越冬长耳鸮的食性研究

通过对保定城区越冬的长耳鸮种群食性分析,观察到其食物组成中以鼠类为主,黑线仓鼠、黑线姬鼠、大仓鼠、褐家鼠、小家鼠和田鼠等占其食物总量76.29％。借此分析保定城郊鼠的种类及动态,指出黑线仓鼠为该地各月份中的优势种。越冬长耳鹗捕食的鼠主要是亚成体、成体,占捕食总鼠量的68.58％,能有效地起到控制鼠类种群数量增殖的作用。     

The effect of aggressiveness on the population dynamics of a territorial bird

A central issue in ecology lies in identifying the importance of resources, natural enemies and behaviour in the regulation of animal populations. Much of the debate on this subject has focused on animals that show cyclic fluctuations in abundance. However, there is still disagreement about the role of extrinsic (food, parasites or predators) and intrinsic (behaviour) factors in causing cycles. Recent studies have examined the impact of natural enemies, although spatial patterns resulting from restricted dispersal or recruitment are increasingly recognized as having the potential to influence unstable population dynamics. We tested the hypothesis that population cycles in a territorial bird, red grouse Lagopus lagopus scoticus, are caused by delayed density-dependent changes in the aggressiveness and spacing behaviour of males. Here we show that increasing aggressiveness experimentally for a short period in autumn reduced recruitment and subsequent breeding density by 50%, and changed population trajectories from increasing to declining. Intrinsic processes can therefore have fundamental effects on population dynamics.     

Relationship between El Nino /South Oscillation (ENSO) and population outbreaks of some lemmings and voles in Europe

Ecologists have been puzzled by population cycles of lemmings and voles for the over 70 years. At present, our understanding and explanation to this phenomenon remain controversial. Recently, El Ni?o/South Oscillation has attracted attention of ecologists on its links with population outbreaks of terrestrial animals. This paper aims to investigate the statistical relationship between outbreaks of microtine rodents and ENSO events by scanning available literature. During 1862—1894, outbreaks of Norway lemmings in Norway tended to occur in the Southern Oscillation Index (SOI) peak years or 1 year after the SOI peak years with an approximate significance level ( p = 0.057). During 1885—1931, outbreaks of voles in France tended to occur 1 year before the SOI peak years (p = 0.01). During 1946—1993, outbreaks of lemmings and voles in North Finland tended to occur 1 year before the SOI peak years with a significant level (p = 0.022); the peaks of population abundance corresponded well to the SOI trough years (equal to 1 year before the SOI peak years). Outbreaks of common voles in Poland during 1946—1975 tended to occur in the SOI peak years or 1 year before the SOI peak years (p = 0.011), and also tended to occur 1 year before the SOI peak years (p = 0.030). It was also found that the rodent outbreaks in Norway and France, rodent outbreaks in Finland and Poland synchronized well. It was suggested that the ENSO-related climate or food were key factors in causing outbreaks of microtine rodents in Europe.     

Diversity of Plant Species of Alpine Grassland in Nakchu of Tibet, China

0Introduction Biologicaldiversityconcernedwiththesumofvariouslivingbeingsandtheirprocesses,aswellasthebasisofharmonious coexistencebetweenmanandnatureplaysanimportantroleinecology,economy,esthetics,ethics,etc.Duetodeteriorationofglobal environment,acceler…     

Evolutionary change in the insulin receptors of hystricomorph rodents

INSULIN receptors have been thought to have remained unaltered despite evolutionary changes in the hormone(1). Because insulins from hystricomorph rodents are known to be highly substituted compared with other mammalian insulins, we decided to investigate the insulin receptor of some hystricomorphs to determine whether evolutionary change had occurred within the receptor itself. Here we present the first evidence that hystricomorph rodent insulin receptors have undergone evolutionary change.     

白鹤在鄱阳湖越冬生境特性及其对湖水位变化的响应

鄱阳湖是世界上重要的白鹤越冬栖息地,白鹤越冬主要集中在鄱阳湖国家级自然保护区。从保护区地形地貌和气象水文特征分析入手,研究了这一区域的湿地植物生态系统的结构和白鹤越冬期的生境与取食情况。结果表明,保护区的浅碟形湖生物多样性丰富,对白鹤在鄱阳湖越冬具有重要意义;碟形湖保持适当水深、并缓慢下降是影响取食歇息的重要条件;食物丰富性与取食可及性是白鹤选择取食地的重要因素;辽阔的水域、较好的水环境和适宜的水深是白鹤越冬的基本前提。白鹤在鄱阳湖越冬与鄱阳湖水位变化及湿地生态系统的结构和演变相适应,对鄱阳湖水位极端变化具有一定的调节能力,但这种能力较为有限。     

青海河南高寒草地生态系统健康评价

以青海省河南县高寒草地为研究区域,从"植被状况-土壤状况-干扰状况-生态系统价值"4个方面的17个指标构建高寒草地生态系统健康评价体系(目标层A、准则层B、因子层C).利用层次分析法确定评价体系中各指标权重,最后利用综合指数法进行高寒草地生态系统健康评价.结果表明:准则层中植被和土壤状况所占权重较大,分别为0.453 4和0.298 4,在高寒草地生态系统健康评价体系中占有主要地位,其中,因子层土壤有机质、地上生物量和植被盖度权重较大,分别为0.168 2,0.164 9,0.164 9,对高寒草地生态系统健康影响显著,虫口密度、土壤碳储能力和牧草生产对草地生态系统健康影响较小,其权重分别为0.007 5,0.010 5,0.010 5.青海河南高寒草地生态系统健康状况评价较好,除样地7外皆属于健康之列.但样地3和样地5评分较低,偏向恶化.应在草地处于初级退化阶段时,积极采取保护措施.     

2003—2020年新疆北部积雪因子时空变化分析

积雪作为冰冻圈的活跃因子之一,对气候环境的敏感性使其能够快速反映出与气温、降水等气候因素的关系变化,并影响着全球水文变化。对新疆北部地区2003年6月—2021年6月的中分辨率成像光谱仪(moderate resolution imaging spectrometer, MODIS)逐日积雪数据进行去云处理,并基于像元计算了积雪覆盖比例(snow cover percentage, SCP)、积雪覆盖日数(snow cover days, SCD)、积雪开始时间(snow onset day, SOD)和积雪结束时间(snow end day, SED)。实验结果表明：积雪产品相对于气象站点数据的总精度达到91.47%,有利于提高对积雪因子的时空变化分析。新疆北部地区SCD空间分布差异较大,SCD随海拔的升高而增加,SOD随海拔升高而提前,主要在11月和12月出现;SED随海拔升高而推迟,主要在2月和3月出现;夏季平均SCD最少,主要分布于天山中部以及阿尔泰山北部区域,约占3.35%,冬季平均SCD最为明显,大于60 d的区域占46.3%;而SCP在1月达到最大,7月和8月最小。趋势变...     

Relationship between El Niño /South Oscillation (ENSO) and population outbreaks of some lemmings and voles in Europe

Ecologists have been puzzled by population cycles of lemmings and voles for the over 70 years. At present, our understanding and explanation to this phenomenon remain controversial. Recently, El Niño/South Oscillation has attracted attention of ecologists on its links with population outbreaks of terrestrial animals. This paper aims to investigate the statistical relationship between outbreaks of microtine rodents and ENSO events by scanning available literature. During 1862–1894, outbreaks of Norway lemmings in Norway tended to occur in the Southern Oscillation Index (SOI) peak years or 1 year after the SOI peak years with an approximate significance level (p = 0.057). During 1885–1931, outbreaks of voles in France tended to occur 1 year before the SOI peak years (p = 0.01). During 1946–1993, outbreaks of lemmings and voles in North Finland tended to occur 1 year before the SOI peak years with a significant level (p = 0.022); the peaks of population abundance corresponded well to the SOI trough years (equal to 1 year before the SOI peak years). Outbreaks of common voles in Poland during 1946–1975 tended to occur in the SOI peak years or 1 year before the SOI peak years (p = 0.011), and also tended to occur 1 year before the SOI peak years (p = 0.030). It was also found that the rodent outbreaks in Norway and France, rodent outbreaks in Finland and Poland synchronized well. It was suggested that the ENSO-related climate or food were key factors in causing outbreaks of microtine rodents in Europe.