水盐变化对荒漠植物功能多样性与物种多样性关系的影响

研究植物功能多样性与物种多样性关系对土壤水盐环境的响应规律,有助于掌握胁迫环境下植物多样性的维持机理.本研究分析了艾比湖高、低土壤水盐环境下荒漠植物功能多样性、物种多样性差异及二者间关系在不同水盐环境下的变化规律.结果表明:(1)高水盐环境下植物功能离散度显著低于低水盐环境(P<0.05),物种多样性指数Fish-α显著高于低水盐环境;(2)一元与多元回归分析均表明,高水盐环境下物种多样性对功能多样性RaoQ与FRic指数有显著促进作用,低水盐环境下物种多样性对功能多样性和均匀度有显著促进作用,但对功能离散度具有显著抑制作用(P<0.05);(3)物种多样性对功能多样性的影响在低水盐环境下更显著,预测力更强;(4)功能丰富度、离散度与均匀度能较敏感地反映出荒漠植物功能多样性对水盐变化的响应.本研究有助于理解荒漠植物群落构建机制,并为荒漠植物恢复与管理提供理论参考.     

山西太原市综合公园植物多样性研究

城市公园绿地是城市园林绿地系统的主体,是集中体现城市植物多样性的场所,研究其植物多样性可为城市生物多样性保护提供基础。以山西太原市 17 个综合公园为研究对象,从植物应用的重要值、 Margalef 丰富度、Shannon-Wiener 多样性和 Pielou 均匀度分析其植物多样性,为太原市公园植物多样性保护及公园绿地建设提供参考。研究表明太原市综合公园的植物种类有 78 科 164 属 285 种。植物应用重要值排名前五的种类为大叶黄杨 > 紫叶小檗 > 圆柏 > 国槐 > 金叶女贞。植物丰富度指数为 26.42,乔木层 > 草本层 > 灌木层;多样性指数为 3.13,乔木层 >灌木层;均匀度指数为 0.60,乔木层 >灌木层。木本植物多样性总体评价较高的公园为汾河公园、玉门河公园和晋祠公园;较低的为映山湖公园、长风商务区大平台景观绿化、南海子公园。     

Effects of livestock grazing on an Afromontane grassland bird community in the Bale Mountains of Ethiopia

Livestock grazing has been considered to be one of the major causes for biodiversity degradation worldwide. In this study, we examined this effect on Afromontane grassland birds by comparing their diversity between ungrazed and grazed grassland sites in the northern Bale Mountains, Ethiopia. We counted birds and recorded vegetation height and cover along 28 (14 in each land‐use type) 1 km transects. We used six different diversity measures (richness, evenness, Shannon diversity, taxonomic diversity and taxonomic distinctness) to express bird diversity and explored which of these measures better reveal the diversity pattern. Vegetation structure differed significantly between the two sites; the first two principal components accounted for 78% of the variation. Discriminant function analysis (DFA) showed bird diversity to differ significantly between the two sites; taxonomic diversity (Delta) contributed the most to the difference between the two sites, while species richness contributed the least. The results of ANOVA indicated that all diversity measures, except species richness, were significantly higher in the protected site compared to the unprotected site. In general, this study showed that grazing had negatively affected bird diversity in the study area and the use of taxonomic diversity measures had enabled us to reveal the impact better.     

First insights into fern matK phylogeny

MatK, the only maturase gene in the land plant plastid genome, is a very popular phylogenetic marker that has been extensively applied in reconstructing angiosperm phylogeny. However, the use of matK in fern phylogeny is largely unknown, due to difficulties with amplification: ferns have lost the flanking trnK exons, typically the region used for designing stable priming sites. We developed primers that are either universal or lineage-specific that successfully amplify matK across all fern families. To evaluate whether matK is as powerful a phylogenetic marker in ferns as in angiosperms, we compared its sequence characteristics and phylogenetic performance to those of rbcL and atpA. Among these three genes, matK has the highest variability and substitution evenness, yet shows the least homoplasy. Most importantly, applying matK in fern phylogenetics better resolved relationships among families, especially within eupolypods I and II. Here we demonstrate the power of matK for fern phylogenetic reconstruction, as well as provide primers and extensive sequence data that will greatly facilitate future evolutionary studies of ferns.     

Genetic diversity of Ranunculus acris L. (Ranunculaceae) populations in relation to species diversity and habitat type in grassland communities

Correlates between genetic diversity at intra- and interpopulation levels and the species diversity in plant communities are rarely investigated. Such correlates may give insights into the effect of local selective forces across different communities on the genetic diversity of local plant populations. This study has employed amplified fragment length polymorphism to assess the genetic diversity within and between 10 populations of Ranunculus acris in relation to the species diversity (richness and evenness) of grassland communities of two different habitat types, 'seminatural' and 'agriculturally improved', located in central Germany. Within-population genetic diversity estimated by Nei's unbiased gene diversity (HE) was high (0.258-0.334), and was not correlated with species richness (Pearson's r = -0.17; P = 0.64) or species evenness (Pearson's r = 0.15; P = 0.68) of the plant communities. However, the genetic differentiation between R. acris populations was significantly correlated with the difference in species evenness (Mantel's r = 0.62, P = 0.02), but not with difference in species richness of plant communities (r = -0.17, P = 0.22). Moreover, we also found that populations of R. acris from the 'seminatural' habitat were genetically different (amova, P < 0.05) from those in 'agriculturally improved' habitats, suggesting that gene flow between these habitat types is limited. The results reported in this study may indicate that habitat characteristics influence the genetic diversity of plant species.     

棉区夏玉米田节肢动物群落的研究

系统研究了夏玉米田节肢动物群落的相对多度,丰富度、生态优势度,多样性指散和均匀度的变动。分析提出了以保护利用天敌为主的综合防治对策。     

桃园节肢动物群落的多样性、均匀度和相对稳定性季节动态

对桃园节肢动物群落进行了系统调查,并对数据进行了数学分析．结果表明,群落与植食动物亚群落的多样性指数相关系数为0．9480,两者极显著相关;群落与捕食动物亚群落的多样性指数相关系数为0．7855,两者极显著相关;两个亚群落的多样性均与群落多样性有关,两个亚群落多样性指数间相关系数为0．6741,两者显著相关;群落多样性指数与群落均匀度指数问相关系数为0．7870,两者极显著相关;群落多样性指数与两个亚群落均匀度指数之间均不相关．群落多样性指数(H’),与捕食性动物个体数(Sd)和植食性动物个体数(Sz)之比值(Sd／Sz)相关系数为0．8112,两者极显著相关;与群落物种数(Sz)和个体数(Si)之比值(Sz／Si)相关系数为0．9188,两者极显著相关;与捕食动物类群(科)数(Spl)和植食动物类群(科)数(Szl)之比值(Spl／Szl)不相关。     

Tree biodiversity in protected and logged Bornean tropical rain forests and its measurement by satellite remote sensing

Aim Conservation activities have increasingly focused on issues at the level of the landscape but are constrained by limited data and knowledge relating to biodiversity at this scale. Satellite remote sensing has considerable, but under‐exploited, potential as a source of information on biodiversity at the landscape level. Remote sensing has generally been used to assess biodiversity indirectly, using approaches that often fail to fully exploit the information content of the imagery and typically only with regard to the species richness component of biodiversity. The aim of this paper was to assess the potential of remote sensing as a source of information on the richness, evenness and composition of tree species in a tropical rain forest. Location The test site was a c. 225 km² region centred on the Danum Valley Field Centre, Borneo. This test site contained regions of undisturbed and differentially logged rain forest. Methods Data on tree biodiversity had been acquired for fifty‐two sample plots by standard field survey methods and were used to derive summary indices of biodiversity for seedlings, saplings and mature trees. Differences between logged and unlogged sites were evaluated by comparison of the indices and species accumulation curves. A Landsat Thematic Mapper (TM) image of the site acquired close to the date of the field survey was obtained and rigorously pre‐processed. Feedforward neural networks were used to derive predictions of biodiversity indices from the imagery. A Kohonen self organizing map neural network was used to ordinate the field data to derive classes of forest defined by relative similarity in species composition. The separability of the defined classes in the Landsat TM image was evaluated with a discriminant analysis. Results Analyses of the field data revealed considerable variation in the biodiversity of seedlings, saplings and trees at the site, associated, in part, with differences in logging activities. This variation in biodiversity was manifest in the remotely sensed data. The analyses indicated an ability to (1) predict biodiversity indices, with the highest correlation between predicted and actual index observed for evenness described by Shannon entropy (r = 0.546), but especially to (2) classify nine forest classes defined on the basis of similarity in tree species composition (accuracy 95.8%). Main conclusions Logging activities impacted on biodiversity and the resulting variation in biodiversity was reflected in the remotely sensed imagery. Using methods that exploit more fully the information content of the imagery than those used in other previous studies, a richer representation of biodiversity may be derived. This representation includes estimates of key summary indices of biodiversity, notably richness and evenness, as well as information on species composition. The results indicate that remotely sensed data may be used as a source of information on biodiversity at the landscape scale that may be used to inform conservation science and management.     

Do species evenness and plant density influence the magnitude of selection and complementarity effects in annual plant species mixtures?

Abstract Plant species richness influences primary productivity via mechanisms that (1) favour species with particular traits (selection effect) and (2) promote niche differentiation between species (complementarity). Influences of species evenness, plant density and other properties of plant communities on productivity are poorly defined, but may depend on whether selection or complementarity prevails in species mixtures. We predicted that selection effects are insensitive to species evenness but increase with plant density, and that the converse is true for complementarity. To test predictions, we grew three species of annuals in monocultures and in three‐species mixtures in which evenness of established plants was varied at each of three plant densities in a cultivated field in Texas, USA. Above‐ground biomass was smaller in mixtures than expected from monocultures because of negative ‘complementarity’ and a negative selection effect. Neither selection nor complementarity varied with species evenness, but selection effects increased at the greatest plant density as predicted.