Mountains are key features of the Earth's surface and host a substantial proportion of the world's species. However, the links between the evolution and distribution of biodiversity and the formation of mountains remain poorly understood. Here, we integrate multiple datasets to assess the relationships between species richness in mountains, geology and climate at global and regional scales. Specifically, we analyse how erosion, relief, soil and climate relate to the geographical distribution of terrestrial tetrapods, which include amphibians, birds and mammals. We find that centres of species richness correlate with areas of high temperatures, annual rainfall and topographic relief, supporting previous studies. We unveil additional links between mountain-building processes and biodiversity: species richness correlates with erosion rates and heterogeneity of soil types, with a varying response across continents. These additional links are prominent but under-explored, and probably relate to the interplay between surface uplift, climate change and atmospheric circulation through time. They are also influenced by the location and orientation of mountain ranges in relation to air circulation patterns, and how species diversification, dispersal and refugia respond to climate change. A better understanding of biosphere-lithosphere interactions is needed to understand the patterns and evolution of mountain biodiversity across space and time.

The importance of facilitation to local community dynamics is becoming increasingly recognized. However, the predictability of positive interactions in stressful environments, the balance of competition and facilitation along environmental gradients, and the scaling of local positive interactions to regional distributions are aspects of facilitation that remain unresolved. I explored these questions in a habitat specialist, Delphinium uliginosum, and a moss, Didymodon tophaceus, both found in small serpentine wetlands. I tested three hypotheses: (1) moss facilitates germination, growth, and/or fecundity of D. uliginosum; (2) facilitation is stronger at the harsher ends of gradients in soil moisture, toxicity, and/or biomass; and (3) facilitation is reflected in positive associations at the levels of local abundance and regional occurrence. Although considerable competitive interactions occurred in later life stages, moss strongly facilitated D. uliginosum seedling emergence. There was no evidence that this facilitative effect weakened, or switched to competition, in benign environments. D. uliginosum was more locally abundant and more frequently present, across a large portion of its range, with than without moss, indicating a net facilitative effect in the face of competitive influences. Facilitated recruitment, possibly by seed retention, was found to be an important control on abundance and distribution in this rare species.

For niche differences to maintain coexistence of sympatric species, each species must grow and/or survive better than each of the others in at least one set of conditions (i.e., performance trade-offs). However, the extent of niche differentiation in tropical forests remains highly debated. We present the first test of performance trade-offs for wild seedlings in a tropical forest. We measured seedling relative growth rate (RGR) and survival of four common native woody species across 18 light, substrate, and topography microhabitats over 2.5 years within Hawaiian montane wet forest, an ideal location due to its low species diversity and strong species habitat associations. All six species pairs exhibited significant performance trade-offs across microhabitats and for RGR versus survival within microhabitats. We also found some evidence of performance equivalence, with species pairs having similar performance in 26% of comparisons across microhabitats. Across species, survival under low light was generally positively associated with RGR under high light. When averaged over all species, topography (slope, aspect, and elevation) explained most of the variation in RGR attributable to microhabitat variables (51-53%) followed by substrate type (35-37%) and light (11-12%). However, the relative effects of microhabitat differed among species and RGR metric (i.e., RGR for height, biomass, or leaf area). These findings indicate that performance trade-offs among species during regeneration are common in low-diversity tropical forest, although other mechanisms may better explain the coexistence of species with small performance differences.

Aims Our study aimed to understand the effects and the relative importance of biotic neighborhood and habitat heterogeneity for tree seedling survival in a secondary mixed conifer and broad-leaved forest in Changbai Mountain, north-eastern China. Methods The generalized mixed linear model was used to examine the relative effects of biotic neighborhood and habitat heterogeneity on seedling survival over two years. Important findings Our results showed that both biotic neighborhood and habitat heterogeneity had significant effects on the seedling survival at community level. The local environment suitable for the adult growth was also suitable for seedling survival. The soil moisture and soil available nitrogen exhibited significant positive effects on seedling survival. On the other hand, seedling density had significant negative effects on seedling survival due to the individual competition. Particularly, we found significant negative density-dependent effects on seedling survival which was caused by conspecific adult and seedling neighbors. As expected, with the increasing of seedling survival age, the habitat heterogeneity became more important on seedling survival. These results suggest that both local biotic neighborhood and habitat heterogeneity drive seedling survival in this temperate forest, and their relative importance varies with different seedling age classes and species traits.

基于长白山次生针阔混交林样地, 以520个1 m × 1 m幼苗样方中胸径小于1 cm的乔木幼苗为研究对象, 选取2013年和2014年的幼苗调查数据, 运用广义线性混合模型(GLMM)分析了生物邻体和生境异质性对幼苗存活的影响, 探讨了次生针阔混交林幼苗存活影响因素及物种共存机制。结果表明: (1)适宜大树生长的局域生境同样也适宜幼苗的存活, 幼苗存活率与土壤含水量和有效氮等土壤养分显著正相关。(2)幼苗个体之间存在明显的竞争, 较多的幼苗邻体显著降低幼苗的存活率。同种大树邻体和同种幼苗邻体与幼苗存活显著负相关, 表明存在负密度制约效应。(3)随着幼苗年龄的增加, 生境异质性对幼苗存活的影响逐渐增大。该研究证实了密度制约效应和生境异质性对幼苗存活有着重要影响, 其相对重要性随着幼苗年龄级、功能群以及物种种类而变化。

原始林在全球碳收支中具有重要的意义，其细根在地下碳循环过程中发挥着重要作用。本研究采用连续土钻法对川西亚高山岷江冷杉原始林0～30 cm土层细根（≤2 mm）生物量及其季节动态进行了测定，并采用决策矩阵法对细根生产量和周转速率进行了估算。结果表明：岷江冷杉原始林0～30 cm土层活细根生物量和年生产量分别为286.89 g·m^-2和168.94 g·m^-2·a^-1，平均细根周转速率为0.56 a^-1；细根生物量、生产量和死亡量在生长期内具有明显的动态特征；活细根生物量和生产量总体呈现单峰曲线特征，以9月最大；死细根生物量和死细根/活细根生物量在生长期内总体呈“U型”变化趋势，而死亡量总体呈增加的趋势；土层深度是影响细根动态的重要因素，活细根生物量、死细根生物量、生产量和周转速率随着土层深度的增加呈现下降的变化趋势，而死细根/活细根生物量略有增加。

<EM>Aims</EM> Subalpine dark coniferous forests in western Sichuan, China include natural old-growth forests and successional forests that regenerated mainly following logging over the past 50 years. Both the bamboo and moss forest types are comprised of three different restoration stages: broad-leaved forest 20–40 years old, conifer/broad-leaved mixed forest 50 years old and old-growth dark coniferous forest 160–200 years old. Our objectives were to understand how subalpine dark coniferous forests naturally regenerated following disturbance and determine key factors influencing natural regeneration. <BR><EM>Methods</EM> We investigated densities of seedlings, saplings and small trees of the climax dominant tree species <EM>Abies faxoniana</EM> in 50 quadrats along a gradient of the different successional stages in both the bamboo and moss forest types located at 3 100–3 600 m elevation on north or northwest aspects. <BR><EM>Important findings</EM> The densities of seedlings, saplings and small trees of <EM>A. faxoniana </EM>were generally relatively low in both the bamboo and moss forest types, but higher than that in moss forest types. Key factors enhancing natural regeneration of <EM>A. faxoniana</EM> in the bamboo forest types were density of seed-bearing trees and the stock of fallen wood. Negative factors were coverage of bamboo and thickness of moss. In the moss forest types, the coverage of shrubs and thickness of moss enhanced the occurrence of seedlings of <EM>A. faxoniana</EM> but limited the development of saplings and small trees. <BR>

在川西亚高山米亚罗林区海拔3 100~3 600 m 阴坡、半阴坡, 以立地条件基本一致的箭竹和藓类林型不同恢复阶段 (20~40 a生的箭竹阔叶林、50 a生的箭竹针阔混交林、160~200 a生的箭竹原始暗针叶老龄林; 20~40 a生的藓类阔叶林、50 a生的藓类针阔混交林、160~200 a生的藓类原始暗针叶老龄林) 的群落为研究对象, 共设置了50个样方 (20 m×20 m ), 采用空间代时间的方法分析了岷江冷杉(Abies faxoniana)的天然更新状况, 并采用通径分析法对其影响因子进行分析。结果表明: 箭竹和藓类两种森林类型岷江冷杉幼苗、幼树和小树的密度偏低。对于箭竹林型不同恢复阶段, 岷江冷杉幼苗密度＜幼树密度＜小树密度; 对于藓类林型不同恢复阶段, 藓类阔叶林幼树密度大于幼苗和小树密度, 藓类针阔混交林小树密度大于幼苗和幼树密度, 而藓类原始暗针叶老龄林幼苗密度大于幼树和小树密度。藓类林型岷江冷杉天然更新状况好于箭竹林型。对箭竹林型而言, 影响岷江冷杉天然更新的关键因子为母树密度、倒木蓄积量、箭竹盖度和苔藓层厚度, 其中母树密度和倒木蓄积量对岷江冷杉天然更新起着促进作用, 箭竹盖度和苔藓层厚度对岷江冷杉天然更新起着阻碍作用; 对于藓类林型而言, 影响岷江冷杉天然更新的关键因子为灌木盖度和苔藓层厚度。灌木和苔藓有利于幼苗的发生, 但不利于幼苗向幼树、小树的过渡。

通过模拟增温和功能群去除试验,研究不同功能群的草本植物在岷江冷杉幼苗更新定植过程的作用,分析其在温度升高条件下生理指标的变化.结果表明: 增温提高了岷江冷杉幼苗的存活率和植物体内非结构性碳水化合物含量,但抑制了幼苗的生长和根冠比.岷江冷杉幼苗的非结构性碳水化合物含量,尤其是可溶性糖含量与存活率呈显著正相关.不增温处理中,草本植物降低了幼苗的存活率,促进幼苗的株高生长和地上生物量积累,禾本科植物和杂类草抑制了幼苗根系生长和地下生物量的积累;增温处理中,杂类草的存在提高了幼苗的存活率,莎草科则显著抑制了幼苗根系生长和地下生物量的积累,禾本科植物和杂类草抑制了幼苗的高生长和地上生物量积累.模拟增温提高了林线树种岷江冷杉幼苗的存活率,但使其面临来自草本植物更剧烈的竞争,抑制其生长.

植物光合产物分配受环境因子和生物因子的共同影响。为增进对植物对全球变化响应的理解, 从植物个体水平与群落/生态系统水平综述了植物光合产物分配的影响因子与影响机理的最新研究进展。植物个体在光照增强及受水分和养分胁迫时, 会将光合产物更多地分配到根系; CO₂浓度升高对植物光合产物分配的影响受土壤氮素的制约, 植物受氮素胁迫时, CO₂浓度升高会促进光合产物更多地分配到根系; 反之, 对植物光合产物分配没有影响。植物群落/生态系统的光合产物分配对环境因子的响应不敏感; 光合产物向根系的分配比例随其生长阶段逐渐降低。功能平衡假说、源汇关系假说和相关生长关系假说分别从环境因子、个体发育和环境因子与个体发育协同作用方面阐述了植物光合产物分配的影响机理。在此基础上,指出了未来拟重点加强的研究方向: 1)生态系统尺度的光合产物向呼吸部分的分配研究; 2)地下净初级生产力(belowground net primary productivity, BNPP)研究; 3)温室和野外条件下及幼苗和成熟林光合产物分配对环境因子响应的比较研究; 4)生态系统尺度的多因子控制试验; 5)整合环境因子和个体发育对植物光合产物分配格局的影响研究。

Whether the fraction of total forest biomass distributed in roots, stems, or leaves varies systematically across geographic gradients remains unknown despite its importance for understanding forest ecology and modeling global carbon cycles. It has been hypothesized that plants should maintain proportionally more biomass in the organ that acquires the most limiting resource. Accordingly, we hypothesize greater biomass distribution in roots and less in stems and foliage in increasingly arid climates and in colder environments at high latitudes. Such a strategy would increase uptake of soil water in dry conditions and of soil nutrients in cold soils, where they are at low supply and are less mobile. We use a large global biomass dataset (>6,200 forests from 61 countries, across a 40 °C gradient in mean annual temperature) to address these questions. Climate metrics involving temperature were better predictors of biomass partitioning than those involving moisture availability, because, surprisingly, fractional distribution of biomass to roots or foliage was unrelated to aridity. In contrast, in increasingly cold climates, the proportion of total forest biomass in roots was greater and in foliage was smaller for both angiosperm and gymnosperm forests. These findings support hypotheses about adaptive strategies of forest trees to temperature and provide biogeographically explicit relationships to improve ecosystem and earth system models. They also will allow, for the first time to our knowledge, representations of root carbon pools that consider biogeographic differences, which are useful for quantifying whole-ecosystem carbon stocks and cycles and for assessing the impact of climate change on forest carbon dynamics.

木本植物幼苗是高山林线生态交错区的重要组成部分,其更新对气候变化背景下树线的移动至关重要.本研究通过对近几十年来全球范围内林线生态交错区的木本植物幼苗分布特征、更新机制及其对气候变化响应的研究总结得出:林线生态交错区木本植物幼苗的空间分布类型主要为渐变型和聚集型,且不同分布类型对树线动态的指示意义各异.在全球尺度上,其分布的海拔高限通常与生长季长度、均温和物种特性等有关,而在区域尺度上则多受降水影响.在幼苗更新初期,种源在很大程度上决定了种子的萌发及分布位置,之后微环境的促进作用为幼苗的定植提供庇护,提高其存活率,而在更新后期多种生物和非生物因素及其相互作用则非常关键.气候变暖促使林线生态交错区气温升高、降水充沛,有利于幼苗生长,使其向高海拔区域扩张而成为树线上移的先兆,但部分物种受遗传特性或适应策略影响,仅表现为密度增加,使树线保持相对稳定.未来应借助树轮、¹⁴C等精确定年技术,通过长期的野外定位观测和室内模拟,加强多时空尺度下林线幼苗的空间分布特征和更新机制研究,分析不同类型林线内木本植物幼苗的适应策略,预测气候变化背景下的树线动态,为山地生态系统恢复及保护提供科学依据.

This study quantifies biomass, aboveground and belowground net productivity, along with additional environmental factors over a 2-3year period in Barnawapara Sanctuary of Chhattisgarh, India through satellite remote-sensing and GIS techniques. Ten sampling quadrates 20x20, 5x5 and 1x1m were randomly laid for overstorey (OS), understorey (US) and ground vegetation (GS), respectively. Girth of trees was measured at breast height and collar diameters of shrubs and herbs at 0.1m height. Biomass was estimated using allometric regression equations and herb biomass by harvesting. Net primary productivity (NPP) was determined by summing biomass increment and litter crop values. Aspect and slope influenced the vegetation types, biomass and NPP in different forests. Standing biomass and NPP varied from 18.6 to 101.5Mgha(-1) and 5.3 to 12.7Mgha(-1) a(-1), respectively, in different forest types. The highest biomass was found in dense mixed forest, while net production recoded in Teak forests. Both were lowest in degraded mixed forests of different forest types. OS, US and GS contributed 90.4, 8.7 and 0.7%, respectively, for the total mean standing biomass in different forests. This study developed spectral models for the estimation of biomass and NPP using Normalized Difference Vegetation Index and other vegetation indices. The study demonstrated the potential of geospatial tools for estimation of biomass and net productivity of dry tropical forest ecosystem.

采用开顶式生长室(Open-top chamber, OTC)模拟增温对植被影响的研究方法, 研究了川西亚高山林线交错带糙皮桦(Betula utilis) 和岷江冷杉(Abies faxoniana)幼苗物候及生长特性对模拟增温的响应。结果表明, 温度升高使岷江冷杉幼苗芽开放时间显著提前(15.2 d); 糙 皮桦春季芽物候期变化不显著, 而落叶时间明显推迟(19.7 d), 叶寿命延长(22.8 d)。与对照(CK)相比, OTC内糙皮桦叶面积和岷江冷杉叶片长度及两者侧枝生长速率都显著加快。模拟增温对两物种基径相对生长速率都表现为正效应, 增温对两物种枝叶特性及分布格局表现为不同程度 的正效应、负效应或无影响。不同功能型两物种对模拟增温响应方式存在一定程度差异。