西双版纳热带山地雨林群落乔木树种多样性研究

根据块样地资料对西双版纳热带山地雨林树种多样性特征进行了分析.结果表明,在2 500m²的样地上,随着起测胸径递增,各样地乔木个体数和树种丰富度均表现为依次递减;低海拔带上(850～1000 m)的山地雨林(1、2号样地)的各指数值无一定变化规律,较高海拔带上(1200～2000 m)的山地雨林(3～6号样地)的Shannon-Wiener指数和Simpson指数均表现为依次递减,而Pielou均匀度指数则呈依次递增的趋势.较高海拔带上的山地雨林在较小乔木起测胸径(≥2 cm、≥5 cm、≥10 cm)的树种丰富度、多样性和均匀度指数均要明显大于低海拔带上的山地雨林,而两者在较大乔木起测胸径(≥20 cm、≥30 cm、≥50 cm)的各指数值无明显差异.随着取样面积的递增,各样地树种丰富度、多样性和均匀度指数在取样面积递增到2 000m²处均已趋于平缓.     

Influence of tree hollow characteristics and forest structure on saproxylic beetle diversity in tree hollows in managed forests in a regional comparison

Tree hollows are among the rarest habitats in today''s Central European managed forests but are considered key structures for high biodiversity in forests. To analyze and compare the effects of tree hollow characteristics and forest structure on diversity of saproxylic beetles in tree hollows in differently structured managed forests, we examined between 41 and 50 tree hollows in beech trees in each of three state forest management districts in Germany. During the two‐year study, we collected 283 saproxylic beetle species (5880 individuals; 22% threatened species), using emergence traps. At small spatial scales, the size of hollow entrance and the number of surrounding microhabitat structures positively influenced beetle diversity, while the stage of wood mould decomposition had a negative influence, across all three forest districts. We utilized forest inventory data to analyze the effects of forest structure in radii of 50–500 m around tree hollows on saproxylic beetle diversity in the hollows. At these larger spatial scales, the three forest management districts differed remarkably regarding the parameters that influenced saproxylic beetle diversity in tree hollows. In Ebrach, characterized by mostly deciduous trees, the amount of dead wood positively influenced beetle diversity. In the mostly coniferous Fichtelberg forest district, with highly isolated tree hollows, in contrast, only the proportion of beech trees around the focal tree hollows showed a positive influence on beetle diversity. In Kelheim, characterized by mixed forest stands, there were no significant relationships between forest structure and beetle diversity in tree hollows. In this study, the same local tree hollow parameters influenced saproxylic beetle diversity in all three study regions, while parameters of forest structure at larger spatial scales differed in their importance, depending on tree‐species composition.     

Changes in beta diversity and species functional traits differ between saplings and mature trees in an old‐growth forest

Invasion by generalist tree species can cause biotic homogenization, and such community impoverishment is likely more important in rare forest types. We quantified changes in tree diversity within Carolinian (range in Central Hardwood Forest), central (range in Central Hardwood Forest and Northern Hardwood‐Conifer Forest), and northern species [range reached Northern‐Conifer‐Hardwood/closed Boreal (spruce‐Fir) Forest] in an old forest tract in southern Canada at points surveyed 24 years apart. We asked: How did mature tree and sapling composition and abundance change for the three species’ groups? Did those changes lead to biotic homogenization? Can species’ changes be explained by community traits? We tested for differences in temporal and spatial tree β‐diversity, as well as forest composition and structure, using univariate/multivariate analyses and a community trait‐based approach to identify drivers of change. Major increases occurred in abundance for mature Acer rubrum (northern), while other species decreased (Fraxinus americana, Populus grandidentata); declines were found in A. saccharinum (central) and Cornus florida (Carolinian). Species composition of saplings, but not mature trees, changed due to replacement; no evidence for biotic homogenization existed in either cohort. As a group, northern mature tree species increased significantly, while central species decreased; saplings of pooled Carolinian species also declined. Shade tolerance in mature trees increased, reflecting successional changes, while drought tolerance decreased, perhaps due to changing temperatures, altered precipitation or ground water levels. Saplings showed declines in all traits, probably because of compositional change. Our results demonstrated that saplings can more closely reflect change in forest dynamics than mature trees, especially over short time periods. Based on sapling trends, this remnant could ultimately transition to a mesophytic hardwood stand dominated by A. rubrum and other shade‐tolerant species, creating a more homogeneous forest. While encouraging regeneration for Carolinian and central tree species could ensure high levels of diversity are conserved in the future, it is important to balance this with the primary management goal of maintaining the forest''s old‐growth characteristics.     

Individual‐level leaf trait variation and correlation across biological and spatial scales

Even with increasing interest in the ecological importance of intraspecific trait variation (ITV) for better understanding ecological processes, few studies have quantified ITV in seedlings and assessed constraints imposed by trade‐offs and correlations among individual‐level leaf traits. Estimating the amount and role of ITV in seedlings is important to understand tree recruitment and long‐term forest dynamics. We measured ten different size, economics, and whole leaf traits (lamina and petiole) for more than 2,800 seedlings (height ≥ 10 cm and diameter at breast height < 1 cm) in 283 seedling plots and then quantified the amount of ITV and trait correlations across two biological (intraspecific and interspecific) and spatial (within and among plots) scales. Finally, we explored the effects of trait variance and sample size on the strength of trait correlations. We found about 40% (6%–63%) variation in leaf‐level traits was explained by ITV across all traits. Lamina and petiole traits were correlated across biological and spatial scales, whereas leaf size traits (e.g., lamina area) were weakly correlated with economics traits (e.g., specific lamina area); lamina mass ratio was strongly related to the petiole length. Trait correlations varied among species, plots, and different scales but there was no evidence that the strength of trait relationships was stronger at broader than finer biological and spatial scales. While larger trait variance increased the strength of correlations, the sample size was the most important factor that was negatively related to the strength of trait correlations. Our results showed that a large amount of trait variation was explained by ITV, which highlighted the importance of considering ITV when using trait‐based approaches in seedling ecology. In addition, sample size was an important factor that influenced the strength of trait correlations, which suggests that comparing trait correlations across studies should consider the differences in sample size.     

Mass‐ratio and complementarity effects simultaneously drive aboveground biomass in temperate Quercus forests through stand structure

Forests play a key role in regulating the global carbon cycle, a substantial portion of which is stored in aboveground biomass (AGB). It is well understood that biodiversity can increase the biomass through complementarity and mass‐ratio effects, and the contribution of environmental factors and stand structure attributes to AGB was also observed. However, the relative influence of these factors in determining the AGB of Quercus forests remains poorly understood. Using a large dataset retrieved from 523 permanent forest inventory plots across Northeast China, we examined the effects of integrated multiple tree species diversity components (i.e., species richness, functional, and phylogenetic diversity), functional traits composition, environmental factors (climate and soil), stand age, and structure attributes (stand density, tree size diversity) on AGB based on structural equation models. We found that species richness and phylogenetic diversity both were not correlated with AGB. However, functional diversity positively affected AGB via an indirect effect in line with the complementarity effect. Moreover, the community‐weighted mean of specific leaf area and height increased AGB directly and indirectly, respectively; demonstrating the mass‐ratio effect. Furthermore, stand age, density, and tree size diversity were more important modulators of AGB than biodiversity. Our study highlights that biodiversity–AGB interaction is dependent on the regulation of stand structure that can be even more important for maintaining high biomass than biodiversity in temperate Quercus forests.     

Diversity investigation by application of DNA barcoding: A case study of lepidopteran insects in Xinjiang wild fruit forests,China

To investigate the species diversity of lepidopteran insects in Xinjiang wild fruit forests, establish insect community monitoring systems, and determine the local species pool, we test the applicability of DNA barcoding based on cytochrome c oxidase subunit I (COI) gene for accurate and rapid identification of insect species. From 2017 to 2019, a total of 212 samples with ambiguous morphological identification were selected for DNA barcoding analysis. Five sequence‐based methods for species delimitation (ABGD, BINs, GMYC, jMOTU, and bPTP) were conducted for comparison to traditional morphology‐based identification. In total, 2,422 samples were recorded, representing 143 species of 110 genera in 17 families in Lepidoptera. The diversity analysis showed that the richness indices for Noctuidae was the highest (54 species), and for Pterophoridae, Cossidae, Limacodidae, Lasiocampidae, Pieridae, and Lycaenidae were the lowest (all with 1 species). The Shannon–Wiener species diversity index (H′) and Pielou''s evenness (J′) of lepidopteran insects first increased and then decreased across these 3 years, while the Simpson diversity index showed a trend of subtracted then added. For molecular‐based identification, 67 lepidopteran species within 61 genera in 14 families were identified through DNA barcoding. Neighbor‐joining (NJ) analysis showed that conspecific individuals were clustered together and formed monophyletic groups with a high support value, except for Lacanobia contigua (Denis & Schiffermüller, 1775) (Noctuidae: Hadeninae). Sixty‐seven morphospecies were classified into various numbers of MOTUs based on ABGD, BINs, GMYC, jMOTU, and bPTP (70, 96, 2, 71, and 71, respectively). In Xinjiang wild fruit forests, the family with the largest number of species is Noctuidae, followed by Geometridae, Crambidae, and the remaining families. The highest Shannon diversity index is observed for the family Noctuidae. Our results indicate that the distance‐based methods (ABGD and jMOTU) and character‐based method (bPTP) outperform GMYC. BINs is inclined to overestimate species diversity compared to other methods.     

密度制约对宝天曼落叶阔叶林锐齿栎死亡前后分布格局的影响

为了在温带和亚热带的过渡带中验证森林树木死亡是否受密度制约的影响, 我们在宝天曼国家级自然保护区选择1个100 m×100 m的暖温带落叶阔叶林样地, 用双变量函数g(r)(the pair-correlation function)研究了锐齿栎(Quercus aliena var. acuteserrata)死亡前(活树和枯木统称为死亡前树木)和死亡后(活树为死亡后树木)的分布格局。把样地中的锐齿栎分为幼树(1 cm ≤ DBH<10 cm)、小树(10 cm ≤ DBH<20 cm)和成年树(DBH≥20 cm)3个不同的生长阶段来研究密度制约对空间分布格局的影响机制。结果表明: (1)死亡前锐齿栎在r>5 m尺度呈聚集分布, 死亡后幼树(1 cm≤DBH<10 cm)和成年树(DBH≥20 cm)在1-25 m尺度呈现随机分布, 死亡后小树(10 cm≤DBH< 20 cm)在r<1.5 m和2.5-4.5 m的尺度为随机分布, 在r>5 m的尺度呈聚集分布; (2)采用随机标签零模型和案例-对照设计的方法, 排除生境异质性影响后, 将幼树和小树的分布格局作为案例, 将成年树的分布格局作为对照, 并代表生境异质性的作用, 通过小径级树木与成年树分布格局的对比发现, 密度制约效应对死亡前后的锐齿栎分布格局均具有影响; (3)幼树和小树在成年树周围的分布死亡前为显著聚集分布格局, 死亡后剩余树木的聚集强度下降; 随着与成年树之间距离的增加, 死亡后的幼树(仅包括现存的活树)逐渐向随机分布格局演替。本研究初步表明锐齿栎空间格局受生境异质性的影响并呈现出显著的聚集效应, 排除生境异质性影响后, 锐齿栎死亡前后的空间格局受到密度制约的影响, 这一结果为Janzen-Connell假说提供了支持。     

云冷杉天然次生林死木分布格局及空间关联性

为揭示天然次生林群落演替规律,以吉林省汪清林业局金沟岭林场的云冷杉天然次生林为对象,采用相邻网格法调查样地(100 m×100 m)内每株林木(DBH≥1 cm)的基本特征及坐标位置,研究死木的分布格局及空间关联性。结果表明: 死木的径级分布呈左偏单峰山状分布,其中枯倒木呈多峰山状分布;各树种的死木株数与该树种的总株数没有必然联系;树种死木株数与树种混交度之间存在显著负指数关系;死木主要在0～8 m尺度上呈聚集分布,随着尺度的增大,逐渐转变为随机分布或均匀分布,以随机分布为主;中(10 cm≤DBH＜20 cm)、小径级(1 cm≤DBH＜10 cm)死木在8 m以下的小尺度上的聚集分布是造成死木总体在小尺度上呈聚集分布的主要原因。不同径级死木与不同径级活立木的空间关联性差异较大,死木与幼树(1 cm≤DBH＜5 cm)的关系较为明显,尤其是大径级死木与幼树在2～25 m尺度上呈显著正关联性;死木与小树(5 cm≤DBH＜15 cm)没有明显的关联性;中、小径级死木与中树(15 cm≤DBH＜25 cm)在0～3 m尺度上呈正关联性,与大树(DBH≥25 cm)分别在9、11～14 m以及15、42～45 m尺度上呈负关联性。树种在生物学特性、径级分布和空间布局上的差异影响着死木的株数和径级分布;混交程度低的树种可能出现较多的死木;死木空间分布格局随林木径级和研究尺度的大小产生变化;死木与活立木的空间关联性在不同径级和不同尺度上呈现出明显差异。     

Tree species richness decreases while species evenness increases with disturbance frequency in a natural boreal forest landscape

Understanding species diversity and disturbance relationships is important for biodiversity conservation in disturbance‐driven boreal forests. Species richness and evenness may respond differently with stand development following fire. Furthermore, few studies have simultaneously accounted for the influences of climate and local site conditions on species diversity. Using forest inventory data, we examined the relationships between species richness, Shannon''s index, evenness, and time since last stand‐replacing fire (TSF) in a large landscape of disturbance‐driven boreal forest. TSF has negative effect on species richness and Shannon''s index, and a positive effect on species evenness. Path analysis revealed that the environmental variables affect richness and Shannon''s index only through their effects on TSF while affecting evenness directly as well as through their effects on TSF. Synthesis and applications. Our results demonstrate that species richness and Shannon''s index decrease while species evenness increases with TSF in a boreal forest landscape. Furthermore, we show that disturbance frequency, local site conditions, and climate simultaneously influence tree species diversity through complex direct and indirect effects in the studied boreal forest.     

Spatial heterogeneity of tree diversity response to climate warming in montane forests

Many studies reported biotic change along a continental warming gradient. However, the temporal and spatial change of tree diversity and their sensitivity to climate warming might differ from region to region. Understanding of the variation among studies with regard to the magnitude of such biotic changes is minimal, especially in montane ecosystems. Our aim is to better understand changes in spatial heterogeneity and temporal dynamics of mountain tree communities under climate warming over the past four decades. In 2017, we resurveyed and recorded all tree species from 107 long‐term monitoring plots that were first studied between 1974 and 1976. These plots were located in montane forests in the Giant Panda National Park (GPNP), China. Our results showed that spatial differences were found in tree species diversity changes response to mean annual temperature change over the past four decades. Tree species richness increased significantly under climate warming in Minshan (MS) and Xiaoxiangling (XXL) with higher warming rate than Qionglai (QLS) and Liangshan (LS). The trees species diversity in MS and XXL were more sensitive to climatic warming. MS and XXL should receive priority protection in the next conservation plan of the GPNP. The GPNP should avoid taking a “one‐size‐fits‐all” approach for diversity conservation due to spatial heterogeneity in plant community dynamics.     

基于结构方程模型分析林分空间结构对草本物种多样性的影响

林分空间结构的改变直接影响林下草本物种的多样性。以针叶纯林、针阔混交林和常绿阔叶林为研究对象,采用结构方程模型研究了林分空间结构对林下草本物种多样性的影响,并探讨了林分水平空间结构,垂直空间结构以及林木竞争态势对林下草本物种多样性的影响的相对重要性。结果表明,林分水平空间结构对林下草本的物种多样性指数和物种均匀性指数均存在极显著的影响(P<0.001),影响系数高达0.96和0.89,对林下草本物种丰富度存在显著影响(P<0.01),影响系数为0.22;林分垂直空间结对林下草本丰富度和物种均匀性指数均存在极显著的影响(P<0.001),影响系数分别为0.86和0.43,对林下草本物种多样性指数存在显著影响(P<0.01),影响系数为0.16;林木竞争指数与林下草本丰富度和物种多样性指数也均存在极显著的影响(P<0.001),但影响系数较小,分别为-0.47和-0.30,而对林下草本物种均匀性指数未达到显著影响作用(P>0.05),影响系数仅为-0.04。整体上看,林分水平空间结构、垂直空间结构和林木竞争态势均对林下草本物种多样性有较强的影响作用,但从...     

Edge disturbance shapes liana diversity and abundance but not liana‐tree interaction network patterns in moist semi‐deciduous forests,Ghana

Edge disturbance can drive liana community changes and alter liana‐tree interaction networks, with ramifications for forest functioning. Understanding edge effects on liana community structure and liana‐tree interactions is therefore essential for forest management and conservation. We evaluated the response patterns of liana community structure and liana‐tree interaction structure to forest edge in two moist semi‐deciduous forests in Ghana (Asenanyo and Suhuma Forest Reserves: AFR and SFR, respectively). Liana community structure and liana‐tree interactions were assessed in 24 50 × 50 m randomly located plots in three forest sites (edge, interior and deep‐interior) established at 0–50 m, 200 m and 400 m from edge. Edge effects positively and negatively influenced liana diversity in forest edges of AFR and SFR, respectively. There was a positive influence of edge disturbance on liana abundance in both forests. We observed anti‐nested structure in all the liana‐tree networks in AFR, while no nestedness was observed in the networks in SFR. The networks in both forests were less connected, and thus more modular and specialised than their null models. Many liana and tree species were specialised, with specialisation tending to be symmetrical. The plant species played different roles in relation to modularity. Most of the species acted as peripherals (specialists), with only a few species having structural importance to the networks. The latter species group consisted of connectors (generalists) and hubs (highly connected generalists). Some of the species showed consistency in their roles across the sites, while the roles of other species changed. Generally, liana species co‐occurred randomly on tree species in all the forest sites, except edge site in AFR where lianas showed positive co‐occurrence. Our findings deepen our understanding of the response of liana communities and liana‐tree interactions to forest edge disturbance, which are useful for managing forest edge.     

Habitat fragmentation and logging affect the occurrence of lesser mouse‐deer in tropical forest reserves

Due to rapid urbanization, logging, and agricultural expansion, forest fragmentation is negatively affecting native wildlife populations throughout the tropics. This study examined the effects of landscape and habitat characteristics on the lesser mouse‐deer, Tragulus kanchil, populations in Peninsular Malaysia. We conducted camera‐trap survey at 315 sampling points located within 8 forest reserves. An assessment of site‐level and landscape variables was conducted at each sampling point. Our study provides critical ecological information for managing and conserving understudied populations of T. kanchil. We found that the detection of T. kanchil was attributed to forest fragmentation in which forest patches had four times greater detection of T. kanchil than continuous forest. The detection of T. kanchil was nearly three times higher in peat swamp forest compared to lowland dipterocarp forests. Surprisingly, the detection of T. kanchil was higher in logged forests (logging ceased at least 30 years ago) than unlogged forests. The detection of T. kanchil increased with the presence of trees, particularly those with DBH of 5 cm to 45 cm, canopy cover, number of saplings and palms, number of dead fallen trees, and distance from nearest roads. However, detection decreased with a greater number of trees with DBH greater than 45 cm and higher elevations, and greater detections where creeping bamboo was abundant. We recommend that conservation stakeholders take the necessary steps (e.g., eradicating poaching, habitat degradation, and further deforestation) to support the conservation of mouse‐deer species and its natural habitats.     

Evaluating otter reintroduction outcomes using genetic spatial capture–recapture modified for dendritic networks

Monitoring the demographics and genetics of reintroduced populations is critical to evaluating reintroduction success, but species ecology and the landscapes that they inhabit often present challenges for accurate assessments. If suitable habitats are restricted to hierarchical dendritic networks, such as river systems, animal movements are typically constrained and may violate assumptions of methods commonly used to estimate demographic parameters. Using genetic detection data collected via fecal sampling at latrines, we demonstrate applicability of the spatial capture–recapture (SCR) network distance function for estimating the size and density of a recently reintroduced North American river otter (Lontra canadensis) population in the Upper Rio Grande River dendritic network in the southwestern United States, and we also evaluated the genetic outcomes of using a small founder group (n = 33 otters) for reintroduction. Estimated population density was 0.23–0.28 otter/km, or 1 otter/3.57–4.35 km, with weak evidence of density increasing with northerly latitude (β = 0.33). Estimated population size was 83–104 total otters in 359 km of riverine dendritic network, which corresponded to average annual exponential population growth of 1.12–1.15/year since reintroduction. Growth was ≥40% lower than most reintroduced river otter populations and strong evidence of a founder effect existed 8–10 years post‐reintroduction, including 13–21% genetic diversity loss, 84%–87% genetic effective population size decline, and rapid divergence from the source population (F _ST accumulation = 0.06/generation). Consequently, genetic restoration via translocation of additional otters from other populations may be necessary to mitigate deleterious genetic effects in this small, isolated population. Combined with non‐invasive genetic sampling, the SCR network distance approach is likely widely applicable to demogenetic assessments of both reintroduced and established populations of multiple mustelid species that inhabit aquatic dendritic networks, many of which are regionally or globally imperiled and may warrant reintroduction or augmentation efforts.     

湖南八大公山25 ha常绿落叶阔叶混交林动态监测样地群落组成与空间结构

湖南八大公山国家级自然保护区位于武陵山系北缘, 区内分布有大面积的常绿落叶阔叶混交林, 物种多样性丰富, 群落结构复杂。中国科学院武汉植物园按CTFS (Center for Tropical Forest Sciences)建设规范于2010-2011年在保护区内建设了一个25 ha的动态监测样地, 为亚热带山地森林群落多样性长期动态监测提供了理想的平台。本文初步分析了八大公山25 ha样地的群落组成与空间结构。结果表明: 群落内共有木本植物存活个体186,575株, 隶属于53科114属232种; 个体数超过1,000株的有38个物种(贡献87%的个体数), 个体数最多的物种为黄丹木姜子(Litsea elongata); 样地内稀有种(≤ 25株)种数占样地总物种数的44%, 而个体数仅为样地总个体数的0.4%。样地内个体平均胸径为5.41 cm, 其中68.4%的个体DBH ≤ 5 cm, DBH ≥ 20 cm的个体数(7,474株)仅约占总个体数的4%; 个体胸径直方图呈倒“J”形, 表明样地处于良好更新与正常生长状态。样地的种-面积关系图显示物种数随样地面积的增加而同步增加, 其增长速度由迅速增长逐渐趋于稳定, 取样面积10 ha时可以涵盖90%以上的物种; 1 ha小样地个体数平均为7,261.8 ± 974.8 (SD), 物种数平均为128.2 ± 8.2 (SD), Shannon-Wiener指数平均为3.56 ± 0.11 (SD), Pielou均匀度指数变异最小, 平均为1.69 ± 0.06 (SD); 个体数与各多样性指数均无显著相关, 表明在该样地中物种多样性的取样效应不明显, 物种数量增加的原因可能来自于其他因素的控制。     

The value of scattered trees for wildlife: Contrasting effects of landscape context and tree size

Aim

The biodiversity value of scattered trees in modified landscapes is often overlooked in planning and conservation decisions. We conducted a multitaxa study to determine how wildlife abundance, species richness and community composition at individual trees are affected by (1) the landscape context in which trees are located; and (2) the size of trees.

Location

Canberra, south‐eastern Australia.

Methods

Trunk arthropod, bat and bird surveys were undertaken over 3 years (2012–2014) at 72 trees of three sizes (small (20–50 cm DBH), medium (51–80 cm), large (≥80 cm)) located in four landscape contexts (reserves, pasture, urban parklands, urban built‐up areas).

Results

Landscape context affected all taxa surveyed. Trunk arthropod communities differed between trees in urban built‐up areas and reserves. Bat activity and richness were significantly reduced at trees in urban built‐up areas suggesting that echolocating bats may be disturbed by high levels of urbanization. Bird abundance and richness were highest at trees located in modified landscapes, highlighting the value of scattered trees for birds. Bird communities also differed between non‐urban and urban trees. Tree size had a significant effect on birds but did not affect trunk arthropods and bats. Large trees supported higher bird abundance, richness and more unique species compared to medium and small trees.

Main conclusions

Scattered trees support a diversity of wildlife. However, landscape context and tree size affected wildlife in contrasting ways. Land management strategies are needed to collectively account for responses exhibited by multiple taxa at varying spatial scales. We recommend that the retention and perpetuation of scattered trees in modified landscapes should be prioritized, hereby providing crucial habitat benefits to a multitude of taxa.     

帽儿山天然次生林内主要木本植物空间格局及更新特点

基于帽儿山次生林1 hm²样地的调查数据,将林分分为幼苗(树高H<30 cm)、幼树(H在30～130 cm或H>130 cm同时胸径DBH<5 cm)、中树(DBH 5～10 cm)、大树(DBH≥10 cm)4个大小级,运用O-ring点格局分析方法,分析帽儿山地区次生林内主要木本植物整体及树种人工补植红松、三大硬阔(水曲柳、胡桃楸、黄菠萝),以及榆树的各大小级空间格局及其关联性,探讨该地区次生林更新演替动向,为该地区森林的可持续经营提供依据.结果表明: 样地内更新幼苗2894株·hm^-2,幼树3337株·hm^-2,林分整体更新情况一般.对林分整体而言,幼苗分别与大树、中树和幼树在0～25 m、0～15 m、0～40 m的空间尺度上呈显著正相关,而在其余尺度上均呈显著负相关;幼树与大树、中树分别在0～15 m、0～25 m空间尺度上呈显著正相关,而在其余尺度上无显著关联;大树与中树则在所有尺度上均无相关性.对林分内优势树种而言,红松大树与幼树在所有尺度上主要呈负相关,而三大硬阔、榆树大树与幼树均以不相关为主.人工补植红松幼树与三大硬阔及榆树的各大小级在研究尺度上表现为以负相关为主,三大硬阔和榆树幼树与其他优势种各大小级只在20 m尺度内呈现负相关;三者两两之间在中树及大树阶段在20 m以上的尺度均不相关.帽儿山天然次生林还处于演替的进程当中,在今后的森林资源管理过程中,应当采取积极的人工干预措施促进林分更新,并适时对不合理的空间格局进行调整.     

Functional rarity of plants in German hay meadows — Patterns on the species level and mismatches with community species richness

Functional rarity (FR) — a feature combining a species'' rarity with the distinctiveness of its traits — is a promising tool to better understand the ecological importance of rare species and consequently to protect functional diversity more efficiently. However, we lack a systematic understanding of FR on both the species level (which species are functionally rare and why) and the community level (how is FR associated with biodiversity and environmental conditions). Here, we quantify FR for 218 plant species from German hay meadows on a local, regional, and national scale by combining data from 6500 vegetation relevés and 15 ecologically relevant traits. We investigate the association between rarity and trait distinctiveness on different spatial scales via correlation measures and show which traits lead to low or high trait distinctiveness via distance‐based redundancy analysis. We test how species richness and FR are correlated, and use boosted regression trees to determine environmental conditions that are driving species richness and FR. On the local scale, only rare species showed high trait distinctiveness while on larger spatial scales rare and common species showed high trait distinctiveness. As infrequent trait attributes (e.g., legumes, low clonality) led to higher trait distinctiveness, we argue that functionally rare species are either specialists or transients. While specialists occupy a particular niche in hay meadows leading to lower rarity on larger spatial scales, transients display distinct but maladaptive traits resulting in high rarity across all spatial scales. More functionally rare species than expected by chance occurred in species‐poor communities indicating that they prefer environmental conditions differing from characteristic conditions of species‐rich hay meadows. Finally, we argue that functionally rare species are not necessarily relevant for nature conservation because many were transients from surrounding habitats. However, FR can facilitate our understanding of why species are rare in a habitat and under which conditions these species occur.     

High functional diversity in deep‐sea fish communities and increasing intraspecific trait variation with increasing latitude

Variation in both inter‐ and intraspecific traits affects community dynamics, yet we know little regarding the relative importance of external environmental filters versus internal biotic interactions that shape the functional space of communities along broad‐scale environmental gradients, such as latitude, elevation, or depth. We examined changes in several key aspects of functional alpha diversity for marine fishes along depth and latitude gradients by quantifying intra‐ and interspecific richness, dispersion, and regularity in functional trait space. We derived eight functional traits related to food acquisition and locomotion and calculated seven complementary indices of functional diversity for 144 species of marine ray‐finned fishes along large‐scale depth (50–1200 m) and latitudinal gradients (29°–51° S) in New Zealand waters. Traits were derived from morphological measurements taken directly from footage obtained using Baited Remote Underwater Stereo‐Video systems and museum specimens. We partitioned functional variation into intra‐ and interspecific components for the first time using a PERMANOVA approach. We also implemented two tree‐based diversity metrics in a functional distance‐based context for the first time: namely, the variance in pairwise functional distance and the variance in nearest neighbor distance. Functional alpha diversity increased with increasing depth and decreased with increasing latitude. More specifically, the dispersion and mean nearest neighbor distances among species in trait space and intraspecific trait variability all increased with depth, whereas functional hypervolume (richness) was stable across depth. In contrast, functional hypervolume, dispersion, and regularity indices all decreased with increasing latitude; however, intraspecific trait variation increased with latitude, suggesting that intraspecific trait variability becomes increasingly important at higher latitudes. These results suggest that competition within and among species are key processes shaping functional multidimensional space for fishes in the deep sea. Increasing morphological dissimilarity with increasing depth may facilitate niche partitioning to promote coexistence, whereas abiotic filtering may be the dominant process structuring communities with increasing latitude.     

Effective distance of volatile cues for plant–plant communication in beech

In response to volatiles emitted from a plant infested by herbivorous arthropods, neighboring undamaged conspecific plants become better defended against herbivores; this is referred to as plant‒plant communication. Although plant‒plant communication occurs in a wide range of plant species, most studies have focused on herbaceous plants. Here, we investigated plant‒plant communication in beech trees in two experimental plantations in 2018 and one plantation in 2019. Approximately 20% of the leaves of a beech tree were clipped in half in the spring seasons of 2018 and 2019 (clipped tree). The damage levels to leaves in the surrounding undamaged beech trees were evaluated 90 days after the clipping (assay trees). In both years, the damage levels decreased with a reduction in the distance from the clipped tree. In 2019, we also recorded the damage levels of trees that were not exposed to volatiles (nonexposed trees) as control trees and found that those that were located <5 m away from clipped trees had significantly less leaf damage than nonexposed trees. By using a gas chromatograph–mass spectrometer, ten and eight volatile compounds were detected in the headspaces of clipped and unclipped leaves, respectively. Among them, the amount of (Z)‐3‐hexenyl acetate in clipped leaves was significantly higher than that in nonclipped leaves. Our result suggests that green leaf volatiles such as (Z)‐3‐hexenol and (Z)‐3‐hexenyl acetate and other volatile organic compounds emitted from clipped trees induced defenses in the neighboring trees within the 5 m radius. The effective distances of plant‒plant communication in trees were discussed from the viewpoint of the arthropod community structure in forest ecosystems.