The effects of agricultural fields and human settlements on the use of rivers by wildlife in the mid-Zambezi valley,Zimbabwe

After the eradication of the Tse-Tse fly in the Mid-Zambezi valley, human settlements and fields extended mainly along the main rivers. In order to investigate the consequences of this human development on wildlife diversity we monitored three rivers of the Mid-Zambezi valley in Zimbabwe: Angwa, Manyame and Kadzi. The rivers were divided in segments of 200 m which were checked for spoors in order to assess the number of species and the number of individuals that used the segments. Human settlements were also recorded. We used a GIS to define the spatial characteristics of the fields present along the rivers, and related them to the distribution and abundance of wild species spoors in the river beds and banks. Our results show that the number of species in one segment of the river decreased with the increasing size of the field area bordering the segment. For all the major ungulate species, the numbers of individuals recorded per segment decreased with increasing field area. A similar trend was observed for small and medium-sized carnivores, though they were in lower numbers when present. Our analyses thus confirm that the extension of human agriculture in wildlife areas has an impact on most wild species, but we also define some threshold value of field size above which there seem to be an acceleration of the decrease in wildlife density and diversity: 3.2 ha for medium and small herbivores and carnivores; only the elephant seem to tolerate larger field area with a threshold value of 32 ha.This revised version was published online in May 2005 with corrections to the Cover Date.     

抚育间伐对燕山北部山区山杨林物种多样性的影响

为了了解抚育间伐对燕山北部山区山杨林物种多样性的影响,对山杨林抚育间伐前后的物种多样性进行了调查和分析,结果表明:抚育后林地草本植物的物种多样性高于未抚育林地,抚育间伐林地草本植物的Patrick指数、Margarlef指数、Simpson指数和Shannon-Wiener指数分别为35.0、6.13、0.89和2.76,未抚育样地分别为29.0、4.90、0.32和1.91;抚育林地灌木的Patrick指数、Margarlef指数、Simpson指数和Shannon-Wiener指数分别为9.0、1.41、0.43和0.98,未抚育林地则分别为8.0、1.48、0.68和1.51,除Patrick指数外,抚育林地的其他多样性指数都低于未抚育林地;抚育间伐使乔木层优势种的优势更为明显。由此得出结论,抚育间伐对山杨林的物种多样性有明显影响,但草本、灌木与乔木对抚育间伐的响应有所不同。     

局地尺度高寒草原土壤真菌多样性对地上植物多样性与生产力关系的调控作用

为研究局地尺度高寒草原土壤真菌多样性对地上植物多样性与生产力关系的调控作用，本研究以青海省湟源县局地尺度高寒草原为研究对象，对不同植物多样性梯度的地上生产力、土壤理化性状和土壤真菌多样性等指标进行调查、采样和分析。通过偏回归分析（partial least squares regression，PLSR）、方差分解分析（variance partitioning analysis，VPA）、构建结构方程模型（structural equation model，SEM）等分析手段，分析了土壤真菌多样性对地上植物多样性与生产力关系的调控作用。结果表明，高寒草原植物多样性与地上生产力存在显著线性正相关关系；土壤真菌多样性分别与植物多样性和地上生产力呈显著正相关关系；通过PLSR，VPA，SEM等方法控制土壤非生物因子效应后，真菌多样性与二者的显著正相关关系仍存在。综上所述，局地尺度下青海省湟源县高寒草原土壤真菌多样性是调控地上植物多样性与生产力正向关系的关键生物因子。     

Soil fauna across Central European sandstone ravines with temperature inversion: From cool and shady to dry and hot places

Sandstone massifs with their deep ravines or gorges offer the instructive opportunity to study the response of organisms to steep environmental gradients. In 2008–2010, many groups of soil fauna were studied along transects across three ravines in the Bohemian Switzerland National Park (north-western Czech Republic), a part of the Elbe Sandstone Massif. Each transect included five sampling positions: two opposite edges, two opposite mid-slope positions, and the ravine bottom. The ravines had a specific microclimate characterized by temperature inversion. In general, the cooler and more humid ravine bottoms had also less acid soil with lower carbon content but enriched by litter of deciduous trees and herbs. The other transect positions were characterized by spruce (mid-slopes) and pine (edges) stands with mor humus, exposed to drought in the upper parts. The soil animal communities (identified to species level) differed substantially in dependence on their position along the transects. Ravine bottoms hosted a diverse soil fauna, including a rich macrofauna. The thick duff layer of acid soils on the slopes and edges hosted a poorer fauna but supported high densities of important decomposers such as enchytraeids, oribatid mites and microbivorous nematodes. In general, these were higher on the slopes, presumably due to the drought exposure of the edges. Vertical position in the ravine and soil pH were the most important factors explaining community composition. This confirmed that the area's high geomorphological diversity, leading to steep microclimatic gradients and heterogenous soil conditions, is a major cause of its high biodiversity. A shift in community structure in the lower parts of the ravines, observed after the first half of the study period, was possibly caused by summer flash floods. An increased frequency and severity of dry spells and flash floods due to heavy rains, predicted by relevant climate warming scenarios, will probably have an detrimental effect on the ravines'soil fauna.     

Livestock grazing has minimal effect on the species richness and diversity of semi-arid shrubland in the Western Little Karoo,South Africa

The Succulent Karoo, one of two arid biodiversity hotspots in the world, is known for its high plant species richness, but little is known about the influence of topography and how it mediates the potentially deleterious effects of grazing. Changes in vegetation species composition, cover and species diversity were examined along piosphere gradients on northerly slopes, bottomlands and low-lying plains on 45 farms. Landscapes differed in the plant speciesand life-form composition, species richness and cover, with the more species-rich, heterogeneous grassy northerly slopes distinct from the plains and bottomlands, which were dominated by Pteronia pallens, Psilocaulon junceum and Drosanthenum spp. with more annual and ephemeral species. Overall, species richness declined linearly with decreasing rangeland condition. A weak grazing effect was detected only on the north-facing slopes, where shrubs and grass decreased with intense grazing. Years of overgrazing have resulted in the widespread dominance of P. pallens, especially on the plains and bottomlands, rendering them insensitive to grazing. The current condition of the northern slopes should be maintained and managed such that palatable species can spread to more degraded areas of the landscape.     

Spatiotemporal dynamics of plant diversity in response to farmers’ evolved settlements in Shanghai

The expansion of the Shanghai metropolitan region has caused a substantial amount of farmland to become urbanized. Most farmers have lost their land and have been relocated from villages to new collective settlements, resulting in dramatic changes in the landscape pattern. This study explores the effects of this transformation on the spatiotemporal dynamics of plant diversity. We randomly sampled 22 plots comprising 294 subplots within two crossed transects that pass through 5 traditional villages and 17 new settlements. The results show that resettlement has exerted significant effects on plant species diversity, both temporally and spatially. Temporally, the Gleason index (GI) of total species over time could be ordered as 1990s > 2000s > 1980s, while Shannon’s diversity index (SHDI) was ordered as 2000s > 1990s > 1980s. Spatially, the GI of total species decreased from the urban center to the exurbs or from the inside to the outside of the built-up areas. SHDI was highest in suburbs or ecotones. Furthermore, the GI of total species had significant correlations with those of indigenous species, exotic species, and planted species (r > 0.90, p < 0.01) as well as with the region and location of settlement (r < −0.48, p < 0.01). Both indigenous and exotic species had significant positive correlations with total species richness at 0.01 levels. Generally, compared with traditional settlements, new settlements displayed greater richness and diversity of plant species, primarily because of the exotic species present in new settlements. The farmers’ socio-economic status was found to be the primary cause of differences in species richness. To protect indigenous and wild species, it is necessary to take into account local knowledge in villages to encourage Chinese farmers to participate actively in community greening. A bridge should be built between traditional villages and modern settlements and between the past and future for farmers.     

云南省六个国家级自然保护区外来入侵草本植物与本地植物的关系

为明确不同自然保护区外来入侵草本植物及其与本地植物多样性之间的关系,以我国生物多样性丰富的云南省为研究对象,于2014年对云南省6个国家级自然保护区的82个1 m2小样方(78个100 m2大样方)中外来入侵草本植物和本地植物物种丰富度和密度进行调查,并分析外来入侵草本植物物种丰富度与本地草本植物物种丰富度、外来入侵草本植物密度与本地草本植物密度的关系及对不同自然保护区外来入侵草本植物物种丰富度的差异进行分析。结果显示,共调查发现22种外来入侵草本植物,其中纳板河流域国家级自然保护区种类最多,达14种,金平分水岭国家级自然保护区仅有2种;6个国家级自然保护区本地草本植物的物种丰富度与外来入侵草本植物的物种丰富度之间、本地草本植物密度与外来入侵草本植物密度之间均呈现正、负2种相关关系,其中哀牢山国家级自然保护区本地草本植物的物种丰富度与外来入侵草本植物物种丰富度呈显著负相关,其它5个国家级自然保护区的相关性均不显著。简单回归分析表明自然保护区外来入侵草本植物物种丰富度与本地草本植物物种丰富度、本地草本植物盖度、本地乔灌木物种丰富度呈显著负相关,多元回归分析结果表明乔灌木物种丰富度和经纬度是造成不同自然保护区外来入侵草本植物物种多样性差异的主要原因。     

Changes in the relationship between species richness and belowground biomass among grassland types and along environmental gradients in Xinjiang,Northwest China

The association between biodiversity and belowground biomass (BGB) remains a central debate in ecology. In this study, we compared the variations in species richness (SR) and BGB as well as their interaction in the top (0-20 cm), middle (20-50 cm) and deep (50-100 cm) soil depths among 8 grassland types (lowland meadow, temperate desert, temperate desert steppe, temperate steppe desert, temperate steppe, temperate meadow steppe, mountain meadow and alpine steppe) and along environmental gradients (elevation, energy condition (annual mean temperature (AMT) and potential evapotranspiration (PET)), and mean annual precipitation (MAP)) based on a 2011-2013 survey of 379 sites in Xinjiang, Northwest China. The SR and BGB varied among the grassland types. The alpine steppe had a medium level of SR but the highest BGB in the top soil depth, whereas the lowland meadow had the lowest SR but the highest BGB in the middle and deep soil depths. The SR and BGB in the different soil depths were tightly associated with elevation, MAP and energy condition; however, the particular forms of trends in SR and BGB depended on environmental factors and soil depths. The relationship between SR and BGB was unimodal in the top soil depth, but SR was positively related with BGB in the middle soil depth. Although elevation, MAP, energy condition and SR had significant effects on BGB, the variations in BGB in the top soil depth were mostly determined by elevation, and those in the middle and deep soil depths were mainly affected by energy condition. These findings highlight the importance of environmental factors in the regulations of SR and BGB as well as their interaction in the grasslands in Xinjiang.     

桉树人工林昆虫群落结构及其多样性初步调查

对桉树人工林系统昆虫种类进行调查和鉴定,记录了桉树人工林昆虫种类共有16目63科106种．从群落物种数来看．鞘翅目的物种丰富度最高（20．56％）;从物种的个体数量看,鳞翅目昆虫的数量最多（30．71％）;桉树林昆虫总的群落多样性指数为1．3933,均匀性指数为0．9301,鞘翅目的群落多样性指数（0．2937）和均匀性指数（0．2108）都最大．文中就昆虫群落多样性与稳定性的关系以及如何抑制害虫发生等问题进行了讨论．