长白山高山苔原带雪斑地段牛皮杜鹃群落的土壤氮矿化与净初级生产力

采用土壤温度连续观测和土壤原位培养,研究了长白山高山苔原带雪斑地段牛皮杜鹃群落的土壤温度、土壤氮矿化及净初级生产力.结果表明: 在非生长季的积雪期(10月下旬-5月上旬),土壤养分呈上升趋势,土壤以氮矿化为主,为翌年植物的生长提供了充足的氮素.其中雪斑地段土壤(平均温度-3.0 ℃)的氮矿化能力更强,速效氮增加量为3.88 g·m^-2,非雪斑地段(平均温度-7.5 ℃)为1.21 g·m^-2. 在生长季节(5月中旬-8月下旬),土壤氮素含量下降,以固持为主;秋季植物停止生长后,土壤速效氮又呈上升趋势;到冬季,由于积雪的作用,雪斑地段土壤温度维持在0 ℃左右或略低,促进了土壤氮的矿化,而非雪斑地段土壤温度则处于冻结状态.氮素矿化能力的差异是雪斑地段牛皮杜鹃群落净初级生产力高于非雪斑地段群落的主要原因,也是植被空间分异的重要驱动因子.     

长白山高山苔原季节性雪斑土壤呼吸对温度响应的模拟研究

利用LI-8100土壤呼吸测定系统, 在室内控制温度条件下测定了长白山高山苔原季节性雪斑大白花地榆(Sanguisorba sitchensis (=S. stipulata))群落土壤呼吸对温度的响应过程, 并根据野外连续测定的全年温度, 估算了雪斑群落土壤呼吸的季节变化, 同时模拟气温升高对土壤呼吸的影响。雪斑土壤温度全年大部分时间维持在0 ℃以上, 极端温度变动幅度不超过20 ℃。模拟计算了10 cm深土壤的呼吸强度, 海拔2 036 m处为307.1 g C·m^-2·a^-1, 海拔2 260 m处的呼吸量为270.9 g C·m^-2·a^-1。由于积雪时间长, 冬季呼吸占很大比例, 而且随着海拔的升高比例加大。从海拔2 036 m到2 260 m, 积雪期土壤呼吸分别占全年的42.5% (125.4 g C·m^-2·a^-1)和49.7% (128.7 g C·m^-2·a^-1)。模拟气温升高1 ℃并假设积雪时间减少20天, 冬天的呼吸量减少8%左右, 但全年总呼吸量增加8%左右。升温后, 平均增加的呼吸量为0.25 g C·kg^-1·a^-1 (或22.65 g C·m^-2·a^-1), 冬季呼吸量减少0.118 g C·kg^-1·season^-1 (或10.81 g C·m^-2·season^-1)。     

高山带雪斑对牛皮杜鹃群落生产力的影响

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.     

长白山苔原带土壤碳、氮矿化对氮沉降的响应

高山苔原生态系统的土壤无机氮含量较低,对氮的缓冲性弱而易受外源氮输入的影响.本研究以长白山北坡苔原带土壤为研究对象,通过室内培养试验,以NH₄NO₃为外加氮源,设置3个施氮水平:对照(CK,0 kg·hm^-2),低氮(N₁,25 kg·hm^-2),高氮(N₂,50 kg·hm^-2),分析长白山苔原带土壤碳、氮矿化对氮沉降的响应.结果表明: 氮添加处理对长白山苔原带土壤碳矿化速率影响不显著,但对土壤碳矿化累积矿化量影响显著,N₂抑制了土壤的碳矿化作用.培养40 d后,氮添加处理提高了土壤无机氮含量;而培养80 d后,N₂与N₁的无机氮含量差异不显著,但都明显高于CK,氮输入促进了土壤氮的矿化.培养过程中,N₁处理下的微生物生物量碳、氮高于N₂和CK处理,说明低氮输入对土壤微生物活性的促进作用更明显.在未来氮沉降增加的背景下,长白山苔原土壤碳、氮周转可能加快,提高土壤无机氮含量.土壤中无机氮含量增加,虽然可以为植物生长提供更多生长所需的氮素,但也提高了土壤氮素的流失风险.     

长白山苔原植被变化对土壤呼吸影响研究

气候变化导致长白山苔原由灌木苔原向灌草苔原演化,对土壤呼吸及碳循环造成了重要影响。为了明确植被变化对苔原土壤呼吸的影响,该研究选取了长白山苔原典型的群落,测定分析了不同草本植物盖度下的土壤呼吸的季节动态变化及差异。结果表明：(1)在生长季,3个群落下不同变化阶段样地的土壤呼吸速率均有明显的动态变化,均呈单峰型变化特征;草本植物盖度增加没有改变土壤呼吸的季节动态变化趋势。(2)草本植物盖度增加对土壤呼吸速率有显著影响,随着草本植物盖度的增加,土壤呼吸速率也逐渐增大。(3)不同植物群落下土壤呼吸不同,在草本植物盖度相同的条件下土壤呼吸速率依次为：牛皮杜鹃 小叶章群落>牛皮杜鹃 地榆群落>笃斯越桔 苔草群落。(4)不同群落草本植物盖度增加对土壤呼吸的增速效应不同,牛皮杜鹃 小叶章群落的土壤呼吸增速最快,笃斯越桔 苔草群落的次之,牛皮杜鹃 地榆群落最小;草本植物盖度的增加也使3个群落之间土壤呼吸的差值出现明显的变化。     

高山森林土壤微生物群落结构和功能对模拟增温的响应

将高山森林土壤装入PVC管中(土壤有机层在上、矿质土壤层在下)培养10周,以高山森林土壤年均温为对照,采用室内人工气候箱分别模拟增温2和4 ℃,研究土壤微生物群落和土壤酶活性对温度升高的响应.结果表明: 温度升高显著降低了土壤有机层中细菌、矿质土壤层中革兰氏阴性菌(G^-)PLFAs含量,但对土壤真菌无显著影响.温度升高引起革兰氏阳性菌和阴性菌比值(G⁺/G^-)升高,改变了微生物群落结构.增温对漆酶、β-葡萄糖酶、酸性磷酸酶和N-乙酰葡糖胺糖苷酶活性没有显著影响.土壤微生物群落之间呈现出协同增长的趋势,真菌、细菌、G⁺、G^-等微生物群落之间均呈显著正相关.土壤有机层中β-葡萄糖苷酶与土壤微生物群落对碳源利用的竞争,导致β-葡萄糖苷酶活性与土壤有机层细菌、真菌、G⁺呈显著负相关.高山森林不同土壤微生物类群对增温的响应不同,细菌比真菌对温度的响应更敏感,真菌对增温有一定的耐受能力.     

干旱区琵琶柴群落细根周转对土壤有机碳循环的贡献

尽管干旱区生态系统的脆弱性受到了广泛的关注, 但目前关于干旱区植物细根有机碳与土壤碳循环关系的研究还比较少见。在2010年整个生长季节内, 采用土钻法和内生长法, 对新疆干旱区的琵琶柴(Reaumuria soongorica)群落土壤特性、细根的生物量月动态、生产量和周转进行了研究。结果表明: 琵琶柴群落表层土壤含水量最低, 土壤含水量表现出从浅层到深层逐渐增加的趋势; 而表层土壤的有机碳含量最高, 随着土壤深度的加深, 有机碳含量逐渐降低。细根生物量的月平均值为54.51 g·m^-2, 群落细根生产量在82.76-136.21 g·m^-2·a^-1之间, 琵琶柴群落的细根周转率为2.08 times·a^-1, 通过细根死亡进入土壤中的有机碳为17 g·m^-2·a^-1。这些结果表明: 由于灌丛细根高的周转速率, 细根是干旱区土壤有机碳输入的重要部分。     

植物多样性与生态系统土壤保持功能关系及其生态学意义

测定物种丰富度呈梯度变化的半湿润常绿阔叶林不同次生演替阶段小区地表径流、土壤侵蚀和总磷流失及影响这些过程的植物群落郁闭度、个体密度、胸高断面积、植物叶吸附水,分析物种多样性与生态系统土壤保持功能、稳定性及直接影响土壤保持功能的群落结构、树冠截留间的关系。结果表明,在降雨、坡度、坡向、坡位、土壤类型等水土保持影响因子相同条件下,随着各小区物种多样性的增加,地表产流次数不断下降;在3个降雨季节,物种多样性最低的小区产生地表径流77次,而物种多样性最高小区产生地表径流才9次;系列小区地表径流、土壤侵蚀和总磷流失随着物种多样性增加呈幂指数下降;物种多样性最低的小区地表径流、土壤侵蚀和总磷流失分别为960.20 m³·hm^-2·a^-1,11.4 t·hm^-2·a^-1,127.69 kg·hm^-2·a^-1,而物种多样性最高的小区为75.55 m³·hm^-2·a^-1、0.28 t·hm^-2·a^-1、4.71 kg·hm^-2·a^-1,分别相差12、50和25倍;地表径流、土壤侵蚀和总磷流失变异系数也呈幂指数下降,物种多样性最高的小区地表径流、土壤侵蚀和总磷流失的变异系数分别为57.93、187.94和 59.2,而物种多样性最低的小区变异系数高达287.6、534.21、315.47,分别相差4、3和5倍。物种多样性与影响土壤保持功能的群落郁闭度、密度和胸高断面积呈正相关关系。不同演替阶段植物叶吸附水量差异显著,吸附水量最高的演替阶段是次生半湿润常绿阔叶林,为12.28 t·hm^-2·a^-1, 最低是云南松(Pinus yunnanensis)林, 为4.15 t·hm^-2·a^-1。“植物多样性-土壤保持功能相关群落结构因子及树冠截留效应-生态系统土壤保持功能”的耦合关系表明了植物多样性通过植物群落结构削弱了降雨动能,减少了地表径流,减轻了土壤及营养元素的流失,以间接方式调控生态系统土壤保持功能,维持系统营养的持续性,在不同尺度上实现生态系统生产力。物种多样性的提高,促进了生态系统土壤保持功能的稳定性。植物多样性-生态系统土壤保持过程的研究可能是生态系统稳定性研究的好方法。用植物叶吸附水测定可评价群落树冠截留效应。由于植物多样性与生态系统土壤保持功能间存在相关关系,基于植物多样性对生态系统土壤保持功能作用模式,可增进对生命系统和地球系统界面间相互作用关系的了解。     

落叶松幼苗碳素和氮素的获取与分配对供氮水平的响应

落叶松(Larix gmelinii)是中国东北林区最重要的工业用材树种,而且在北温带森林中具有重要的生态学意义。落叶松的种植区域内气温低、冬季长,氮素矿化速度低,供氮不足常常成为落叶松生长的限制因素。为揭示落叶松生长与氮素营养的关系,采用沙培法设置了1、4、8和16 mmol·L^-1 4个供氮水平,研究了不同供氮条件下落叶松一年生幼苗对碳和氮的获取与分配的规律。结果显示,落叶松幼苗的生物量、全株氮浓度、氮含量、比氮吸收速率均随供氮水平的增加而升高,叶重比(LWR)、茎重比(SWR)及叶氮比(LNR)、茎氮比(SNR)亦随供氮水平的增加而增加,而根重比(RWR)和根氮比(RNR)则随供氮水平的增加而降低。当供氮水平从1 mmol·L^-1增加至8 mmol·L^-1时,落叶松幼苗相对生长速率呈线性增加,而全株氮生产力几乎未受供氮水平的影响;当供氮水平从8 mmol·L^-1增加至16 mmol·L^-1时,全株相对生长速率不再增加,全株氮生产力则显著下降。与全株氮生产力的变化不同,落叶松幼苗的叶氮生产力与供氮水平呈负相关。     

生物结皮-土壤呼吸对冬季低温及模拟增温的响应

以腾格里沙漠东南缘天然植被区藓类结皮和藻-地衣结皮-土壤为研究对象,利用开顶式生长室(OTC),采用Li-8150系统连续测定了冬季(2015年11月—2016年1月)低温环境下两类结皮-土壤呼吸的变化,分析了低温及模拟增温对两类结皮-土壤呼吸的影响.结果表明: 观测期内,藓类结皮、藻-地衣结皮-土壤呼吸速率分别为-0.052～0.418、-0.032～0.493 μmol·m^-2·s^-1,且藓类结皮显著高于藻-地衣结皮-土壤系统.不同类型结皮-土壤呼吸速率与5 cm土壤温度和土壤体积含水量均呈显著线性正相关,增温主要是通过加速土壤水分蒸散而抑制生物结皮-土壤呼吸速率.在整个观测期,藓类结皮-土壤系统累计排放9.90 g C·m^-2,显著高于藻-地衣结皮-土壤系统的7.00 g C·m^-2.研究区生物结皮-土壤系统冬季累计排放7.40 g C·m^-2,是该荒漠生态系统全年碳收支的重要组成部分.     

Landscape patterns of litter decomposition in alpine tundra

A two-year study of the decomposition of alpine avens (Acomastylis rossii) foliage in alpine tundra of the Front Range of Colorado demonstrated a strong landscape-mediated effect on decay rates. Litter on sites with intermediate amounts of snowpack decayed more rapidly than litter on sites with larger or smaller amounts of snow. Annual decay constants (k-values) of this foliage ranged from-0.33 in dry tundra to-0.52 in moist tundra to-0.47 in the wettest habitat. No site differences in mass loss of litter were detected until late winter-early spring of the first year of decomposition, when significantly faster decomposition was observed for litter beneath the snowpack. In spite of obvious landscape-related patterns in rates of litter decomposition, total microarthropod densities in the top 5 cm of soil did not differ among habitats. However, the relative abundance of the oribatid and prostigmatid mites did vary significantly across the landscape in relation to the moisture gradient. Oribatid mites comprised a greater proportion of total mites in wetter areas. Microarthropod densities and composition, as well as patterns of decomposition, were compared with previous alpine, as well as arctic tundra, studies. The effects of soil invertebrates on decomposition rates in the alpine were evaluated with a mushroom litterbag decomposition experiment. Naphthalene was used to exclude fauna from a subset of litterbags placed in mesic and xeric habitats. Mushrooms without naphthalene additions decayed significantly faster in the mesic sites. Densities of invertebrates were also greater on mushrooms in these mesic sites. Mushrooms placed in xeric sites generally lacked fauna. Thus, both the activities and the composition of the detritus-based food web appear to change substantially across the moisture gradient found in alpine tundra.     

The consequences of multiple resource shifts on the productivity and composition of alpine tundra communities: inferences from a long-term snow and nutrient manipulation experiment

Background: Gradients in the amounts and duration of snowpack and resulting soil moisture gradients have been associated with different plant communities across alpine landscapes.

Aims: The extent to which snow additions could alter plant community structure, both alone and in combination with nitrogen (N) and phosphorus (P) additions, provided an empirical assessment of the strength of these variables on structuring the plant communities of the alpine tundra at Niwot Ridge, Colorado Front Range.

Methods: A long-term snow fence was used to study vegetation changes in responses to snowpack, both alone and in conjunction with nutrient amendments, in plots established in dry and moist meadow communities in the alpine belt. Species richness, diversity, evenness and dissimilarity were evaluated after 20 years of treatments.

Results: Snow additions, alone, reduced species richness and altered species composition in dry meadow plots, but not in moist meadow; more plant species were found in the snow-impacted areas than in nearby controls. Changes in plant community structure to N and N + P additions were influenced by snow additions. Above-ground plant productivity in plots not naturally affected by snow accumulation was not increased, and the positive responses of plant species to nutrient additions were reduced by snow addition. Plant species showed individualistic responses to changes in snow and nutrients, and indirect evidence suggested that competitive interactions mediated responses. A Permanova analysis demonstrated that community dissimilarity was affected by snow, N, and P additions, but with these responses differing by community type for snow and N. Snow influenced community patterns generated by N, and finally, the communities impacted by N + P were significantly different than those affected by the individual nutrients.

Conclusions: These results show that changes in snow cover over a 20-year interval produce measureable changes in community composition that concurrently influence and are influenced by soil nutrient availability. Dry meadow communities exhibit more sensitivity to increases in snow cover whereas moist meadow communities appear more sensitive to N enrichment. This study shows that the dynamics of multiple limiting resources influence both the productivity and composition of alpine plant communities, with, species, life form, and functional traits mediating these responses.     

退化中的长白山西坡灌木苔原优势种分布差异

长白山苔原带植被正在发生显著变化,灌木苔原中灌木植物分布范围萎缩,重要值下降。通过样方调查数据,分析灌木苔原中优势种的变化,灌木分布格局和灌木群落结构特征沿海拔的差异,旨在揭示长白山灌木苔原退化的区域差异,为明确其退化机理提供基础数据。研究表明:(1)长白山西坡灌木苔原退化严重,多种草本植物已经侵入,并成为优势种。目前7个优势种中灌木仅占2席,草本植物占据5席,与1979年的样方调查结果相比灌木优势种的数量和地位都明显下降。7个优势种均为聚集分布,各优势种分布呈现斑块化、分离化,统一的灌木苔原面临解体;大部分灌木苔原群落中,出现了草本层,苔原带下部灌木苔原中草本层高于灌木层,物种组成和群落形态接近草木苔原。(2)灌木在各海拔均仍有广泛分布,但其空间分布格局明显不同。在海拔2300m以下,灌木的分布产生较强的聚集现象,特别是在海拔2100m以下这种聚集分布现象更为突出;在海拔2300m以上灌木的聚集程度较弱。(3)长白山西坡灌木苔原退化的区域分异明显,在海拔2100m以下灌木苔原退化严重,成为草-灌苔原;在海拔2100—2300m之间,灌木苔原退化较严重,成为灌-草苔原;在海拔2300m以上,退化较轻,仍为灌木苔原。由此推断,长白山西坡灌木苔原的退化机理应包括两个方面:草本植物入侵,种间竞争导致灌木退化,以及环境变化导致灌木退化,二者皆可能是全球气候变化的结果。     

高寒草甸地下根系生长动态对积雪变化的响应

2013年11月至2014年8月在青藏高原东缘红原县高寒草甸通过人工堆积的方法,进行了积雪量野外控制试验。以自然降雪的积雪量为对照(CK),设置了S1、S2和S3(积雪量分别为自然对照的2倍、3倍和4倍)3个处理,运用微根窗法追踪研究了积雪量改变后高寒草甸植被根系生长动态,并测定了积雪变化对土壤温度的影响。结果表明:高寒草甸植被根系生长存在明显的季节性变化,随着时间的推移,根系表面积、根尖数量及现存量逐渐增加并在8—9月达到最大值;当冬季积雪量达到143.4mm(S1),对根系生长最为有利(根系表面积、根尖数量、现存量及生产量最大),根系生长旺盛期(净生产速率较高)有所提前和延长,但随着积雪量进一步增加,积雪对根系生长的正效应逐渐降低,根系生长旺盛期逐渐推迟甚至消失;研究还发现,随着积雪量增加,0—10 cm土层土壤温度逐渐降低,相似的变化规律也出现在10—20 cm土层,但在时间上有所延迟;相关性分析表明,在不同土层中,根系生长与土壤温度均呈正相关。因此,积雪变化通过改变土壤温度影响高寒草甸植物根系的生长发育,最终可能会影响高寒草甸生态系统的碳分配与碳循环过程。     

Where do the treeless tundra areas of northern highlands fit in the global biome system: toward an ecologically natural subdivision of the tundra biome

According to some treatises, arctic and alpine sub‐biomes are ecologically similar, whereas others find them highly dissimilar. Most peculiarly, large areas of northern tundra highlands fall outside of the two recent subdivisions of the tundra biome. We seek an ecologically natural resolution to this long‐standing and far‐reaching problem. We studied broad‐scale patterns in climate and vegetation along the gradient from Siberian tundra via northernmost Fennoscandia to the alpine habitats of European middle‐latitude mountains, as well as explored those patterns within Fennoscandian tundra based on climate–vegetation patterns obtained from a fine‐scale vegetation map. Our analyses reveal that ecologically meaningful January–February snow and thermal conditions differ between different types of tundra. High precipitation and mild winter temperatures prevail on middle‐latitude mountains, low precipitation and usually cold winters prevail on high‐latitude tundra, and Scandinavian mountains show intermediate conditions. Similarly, heath‐like plant communities differ clearly between middle latitude mountains (alpine) and high‐latitude tundra vegetation, including its altitudinal extension on Scandinavian mountains. Conversely, high abundance of snowbeds and large differences in the composition of dwarf shrub heaths distinguish the Scandinavian mountain tundra from its counterparts in Russia and the north Fennoscandian inland. The European tundra areas fall into three ecologically rather homogeneous categories: the arctic tundra, the oroarctic tundra of northern heights and mountains, and the genuinely alpine tundra of middle‐latitude mountains. Attempts to divide the tundra into two sub‐biomes have resulted in major discrepancies and confusions, as the oroarctic areas are included in the arctic tundra in some biogeographic maps and in the alpine tundra in others. Our analyses based on climate and vegetation criteria thus seem to resolve the long‐standing biome delimitation problem, help in consistent characterization of research sites, and create a basis for further biogeographic and ecological research in global tundra environments.     

Seedling demography in an alpine ecosystem

Seedling establishment has long been believed to be rare on alpine tundra because of predicted life history trade-offs, the clonality of alpine species, and the harshness of the alpine climate. Contrary to the idea that seedlings are rare on alpine tundra, a 4-yr demographic study of seedlings at Niwot Ridge, Colorado, USA, found seedlings at high densities, particularly in wetter plant communities. Higher germination densities were associated with higher soil moistures both across communities and across time. Mortality of seedlings was highest in the first year and decreased in subsequent years. Species' abundances differed between seedling and adult populations. Many forbs that lacked vegetative reproduction were significantly more abundant among seedling populations, and many monocots and clonal forbs were more abundant among adult populations. In a comparison with published demographic rates, seedling recruitment and mortality rates of Niwot Ridge species fell above or within rates for a wide range of perennial species. Therefore, germination and seedling establishment stages are no more limiting to sexual reproduction in alpine plants than in other perennial plants.     

长白山高山冻原植物群落的数量分类和排序

本文用目前在国际上比较先进的双向指示种分析(TWINSPAN)多元等级分划分类方法和无趋势对应分析(DCA)排序方法对长自山高山冻原植物群落进行了研究。研究结果表明:DCA的第2轴与长白山高山冻原59个植物群落类型的土壤水分梯度紧密相关, TWINSPAN将长白山高山冻原59个植物群落分为12组。此外, 本文还对长白山高山冻原植物群落的TWINSPAN和DCA分类结果与经典分类方法对其分类的结果进行了比较。     

Tundra plant structure and production in relation to the environment

The alpine and polar climatic limit for growth of woody plants is very much dependent on the mean temperatures of the warmest three or four summer months. Tundra plants with perennating buds close to the ground are sheltered by insulating snow cover. Many tundra plants can grow at temperatures 5–10°C below 0°C and also have low optimum temperatures. Total net production of tundra plants may be as high as 900 g/m²/yr as dry weight in moist and eutrophic low alpine shrub tundra and in antarctic moss mats. The variation in tundra plant production is often observed to be greater between different stands (communities) within one locality than between localities, because of very important variation in soil moisture and nutrients between the stands. On a global scale the biomass of vascular plants increases by an order of magnitude from the climatic severe polar desert to semidesert and again from there to moist shrub tundra. The cryptogam biomass increases only 2–10 fold from polar desert to low arctic shrub tundra. To a certain limit unfavourable climatic conditions are worse to above- than to belowground plant parts. Highest root biomass compared to top (up to 20 times higher) is observed in wet monocotyledonous polar and alpine communities. In polar desert root biomass is small again, as compared to tops and also in lower latitudes and altitudes of temperate regions.Presented at he Eighth International Congress of Biometeorology, 9–14 September 1979, Shefayim, Israel.     

Scavenger community structure along an environmental gradient from boreal forest to alpine tundra in Scandinavia

Scavengers can have strong impacts on food webs, and awareness of their role in ecosystems has increased during the last decades. In our study, we used baited camera traps to quantify the structure of the winter scavenger community in central Scandinavia across a forest–alpine continuum and assess how climatic conditions affected spatial patterns of species occurrences at baits. Canonical correspondence analysis revealed that the main habitat type (forest or alpine tundra) and snow depth was main determinants of the community structure. According to a joint species distribution model within the HMSC framework, species richness tended to be higher in forest than in alpine tundra habitat, but was only weakly associated with temperature and snow depth. However, we observed stronger and more diverse impacts of these covariates on individual species. Occurrence at baits by habitat generalists (red fox, golden eagle, and common raven) typically increased at low temperatures and high snow depth, probably due to increased energetic demands and lower abundance of natural prey in harsh winter conditions. On the contrary, occurrence at baits by forest specialists (e.g., Eurasian jay) tended to decrease in deep snow, which is possibly a consequence of reduced bait detectability and accessibility. In general, the influence of environmental covariates on species richness and occurrence at baits was lower in alpine tundra than in forests, and habitat generalists dominated the scavenger communities in both forest and alpine tundra. Following forecasted climate change, altered environmental conditions are likely to cause range expansion of boreal species and range contraction of typical alpine species such as the arctic fox. Our results suggest that altered snow conditions will possibly be a main driver of changes in species community structure.