Community richness and stability in agricultural landscapes: The importance of surrounding habitats

In this paper, the role played by habitat diversity in the landscape on species richness and on the stability of farmland bird communities was investigated. Species richness was estimated on 374 samples monitored in farmland by the French breeding bird survey during the 2001–2005 period. A capture–recapture approach was used to estimate species richness accounting for the variation in detection probability among species of the 100 most common species detected in farmland. Landscape structure and composition were measured both in farmland and in adjacent habitats. The independent effect of each variable on community richness and stability was further assessed using hierarchical variance partitioning and taking spatial autocorrelation into account. A strong matrix effect was detected: non-cropped land deeply influenced richness and stability of bird assemblages.     

采煤塌陷对地表植物群落特征的影响

为了研究采煤塌陷对地表植被组成及其多样性的影响,对陕西省神府-东胜补连塔煤矿采煤塌陷区不同塌陷年限(2、7、12、17 a)区域和未塌陷区域(对照)植被进行抽样调查与分析. 结果表明:该区域共有14科39属46种植物,主要为草本植物;采煤塌陷对植被种类组成、物种分布有很大影响,导致植物种类显著减少31.03%~44.83%. 塌陷区优势种较对照区有较大变化,优势种由多年生草本植物演变为一二年生草本植物;但是不同塌陷年限区域植物优势种基本稳定,主要为看麦娘(Alopecurus aequalis)、烛台虫实(Corispermum candelabrum)、刺叶藜(Chenopodium aristatum)等. 采煤塌陷导致植株密度显著下降58.62%~68.00%、物种丰富度显著下降17.43%~27.00%、Margalef丰富度指数显著降低4.07%~22.76%,但植被盖度差异不显著. 采煤塌陷显著影响植物群落多样性,其中,塌陷12和17 a样地植被Margalef丰富度指数和Shannon-Wiener多样性指数较塌陷2 a样地显著提高. 群落排序结果表明,物种分布与塌陷有明显相关性. 塌陷区植株密度及其植被组成中多年生草本种数很难恢复到对照区水平,植被恢复进程十分缓慢.      

Vegetation patterns and nature reserve construction in an extremely-arid desert in Anxi,NW China's Gansu Province

Anxi County is located in the northwestern part of the Hexi Corridor in gansu Province and has the sole national level nature reserve of extremely-arid desert in China.Phytosociological methods (Braun-Blanquet,1964) are used to classify plant community types in this area.Eleven are disting uished,including six of deserts,four of oases and one transitional type between deserts and oases.Direct gradient analysis (DCA) is employed to correlate the distribution of plant communities to physiogeographic conditions.This study makes clear that water is the most important ecological factor for the distribution of plant species and communities in this area.The effects of water have been demonstrated in different ways.A vegetation gradient from lower altitude to higher altitude in the southern part of the reserve is driven by a precipitation gradient.The effects of the depth of ground water table contribute to the differentiation of vegetation from desert to oasis in the flat area.In a finer scale,the washed gullies have obviously higher species richness and also higher vegetation cover than the surround gobi surfaces,possibly caused by the effects of floods.The vegetation patterns demonstrate that the area of Anxi County is a complete landscape unit.The range of the current nature reserve is not large enough for the purpose of conserving the unique biodiversity in this area.     

Endemic pollinator response to organic vs. conventional farming and landscape context in the Cape Floristic Region biodiversity hotspot

The effects of organic management and landscape context on two highly endemic and important pollinator taxa (bees and monkey beetles) were studied in the Cape Floristic Region (CFR) biodiversity hotspot, where a quarter of the land is intensively managed mostly for grape production. This functional group was chosen as there is concern worldwide over pollinator decline, particularly in regions of high levels of endemism of both flora and fauna such as the CFR. Species richness and abundance of bees and monkey beetles were sampled and compared between organic and conventional vineyards, with natural vegetation as reference habitat. Species richness of monkey beetles, but not the species richness of bees, benefited from organic compared to conventional vineyard management. Our findings support the hypothesis that the effects of landscape context and management may be taxon dependent. Monkey beetles have been suggested as strong indicators of disturbance. These beetles are among the most important pollinator guilds in the CFR, as they help to sustain the endemic vegetation of this region. Protection of the remaining natural habitat in close proximity to farmland is an imperative conservation strategy in this region.     

浑太河流域鱼类生物完整性指数构建与应用

为了解决在不同区域和不同河流类型间等大尺度范围内F-IBI(鱼类生物完整性指数)评价方法体系的建立问题,以浑河-太子河(下称浑太河)流域为研究区域,构建符合区域性特征的生物完整性评价体系并进行应用研究. 于2014年5月对浑太河流域32个采样点的鱼类进行采样调查,根据鱼类群落特征的空间差异和浑太河流域水生态分区,将采样点分为中上游和下游区域两种类型. 通过综合栖息地和水质的标准化方法确定参照点和受损点,依据候选指标分布范围检验、敏感性分析和相关性检验,筛选出浑太河流域中上游F-IBI核心指标包括总物种数、Shannon-Wiener多样性指数、鲤形目鱼类物种数百分比、雅罗鱼亚科个体数百分比、鳅科鱼类物种数百分比、鲈形目鱼类物种数百分比、杂食性鱼类物种数百分比、肉食性鱼类物种数百分比、敏感性鱼类个体数百分比等9个指标;下游筛选出F-IBI核心指标包括总物种数、Shannon-Wiener多样性指数、鮈亚科鱼类物种数百分比、鲈形目鱼类物种数百分比、虾虎鱼科鱼类物种数百分比、中上层鱼类物种数百分比、东北特有鱼类物种数百分比、无脊椎动物食性鱼类物种数百分比、耐受性鱼类个体数百分比等9个指标. 分别提出了浑太河流域中上游和下游的参数标准化公式和健康评价标准,依此将浑太河流域健康状态划分为极好、好、一般、差和极差5个健康等级. 评价结果表明,浑太河流域健康状况整体偏差,在32个采样点中,健康状况处于差和极差的采样点占采样点总数的37.5%,一般的采样点占21.88%,仅有6.25%的采样点处于极好状态. Pearson相关性分析结果显示,F-IBI分值与电导率、ρ(BOD₅)、ρ(COD_Cr)、ρ(NH₃-N)和ρ(TN)均呈显著负相关,而与栖息地综合指数呈显著正相关,表明F-IBI可有效评估浑太河流域的健康状况.      

Comparison of riparian plant communities under four land management systems in southwestern Wisconsin

Riparian plant community composition is influenced by moisture, erosion, original native plant communities, and current and past land use. This study compared riparian plant communities under four types of management: woody buffer strip, grassy buffer strip, rotational grazing, and continuous grazing. Study sites were located along spring-fed streams in the unglaciated region of southwestern Wisconsin, USA. At each site, plant community surveys were conducted using a point transect method. Among the treatments, woody buffer strips, rotationally grazed and continuously grazed riparian areas had greater plant species richness than grassy buffer strips, and woody buffer strips had the greatest native plant species richness. Reed canarygrass (Phalaris arundinacea L.) was prevalent in grassy buffer strips (44% of all observations), common in woody buffer strips (15%), and rare in sites that were rotationally or continuously grazed (3 and 5%, respectively). Pasture sites had greater proportions of native grasses and grass relatives and moderate levels of overall native species richness. Considered a water quality best management practice, well-managed rotational grazing may be a reasonable alternative to buffer strips which can contribute to protection and enhancement of native vegetation biodiversity.     

Small-scale response of plant species to land-use intensification

Plant communities are affected by land-use and landscape heterogeneity and can be used as indicators of environmental change. At small-scale, species composition and species richness of plant communities are influenced by local environment and by diaspores from the surroundings. Thus, they reflect the influence of both land-use type and land-use diversity. Plant community composition was studied along a gradient of agricultural disturbance in the Morvan Regional Natural Park (Burgundy, France). Six landscape units of 1 km² were selected along a range of increasing land-use intensity. Sixteen 0.2 m² sampling plots per unit were selected according to a grid-based design to estimate the percent cover of all plant species. Pattern analysis showed that local species richness increased from woodland to crop to grassland, and also increased with land-use diversity. Local plant biodiversity was maximized under intermediate disturbance intensity and minimized at low (woodland) and high (crop) disturbance levels.     

The influence of grassland management on ground beetles (Carabidae, Coleoptera) in Swiss montane meadows

Effects of grassland management type and intensity on carabid species richness, number of individuals and species composition were studied in the Swiss Prealps. Carabids were censused in 2001 and 2002 in 21 mown and 20 grazed meadows by means of pitfall traps.Mean species richness was significantly higher in mown plots than in grazed plots and species composition was significantly different between these two management types. Additionally, different species characteristic for mown and grazed plots were found. These results suggest that mown meadows and grazed meadows represent two habitat types for carabid beetles.Within both habitats, management intensity was quantified by fertilizing intensity, the number of cuts, cattle density and/or grazing intensity. The relationship between management intensity and the number of individuals and species was positive. Higher fertilizing intensity was the most important factor for higher species richness and had a significant influence on species composition in both habitats. Other variables positively related to the number of individuals, were the number of cuts in mown meadows and grazing intensity and altitude in grazed meadows. Additionally to fertilizing intensity, cattle density was positively related to the number of species in grazed meadows. These results illustrate that in the extensive management systems found in the Swiss Alps and Prealps, even intensively managed meadows can sustain high carabid diversity and abundance.     

Effect of dung deposition on small-scale patch structure and seasonal vegetation dynamics in mountain pastures

Cattle activity greatly influences plant species composition and biomass production of grassland ecosystems. Dung deposition by cattle together with grazing and trampling can be considered as one of the important factors driving vegetation dynamics in pastures. The objective of this study was to investigate at 10-cm and 1-month resolution the plant community dynamics induced by dung deposition in two plant communities (a mesotrophic and an oligotrophic grassland) in a pasture of the Swiss Jura Mountains. Vegetation was sampled four or three times during the vegetation period in contiguous 10 cm × 10 cm quadrats from the centre of the dung pat to a distance of 60 cm. A lower grazing intensity near the dung pat was recorded for all observation periods. In the mesotrophic grassland the canopy was higher near the dung pat already one week after dung deposition. Vegetation around dung pats was submitted to two opposite fertilizing and grazing gradients, which induced changes in vegetation texture and structure at fine scale and short term. We observed a positive rank correlation between species turnover and distance to the dung for both communities, suggesting a seasonal stabilizing effect of dung on the plant composition of their direct surroundings (0–10 cm) likely due to cattle avoidance. Since dung pats are dropped every year in different locations, they create in the pasture a shifting mosaic of nutrient availability and grazing intensity inducing at seasonal scale micro-successions in plant communities.     

岩性对喀斯特灌丛土壤固氮菌与丛枝菌根真菌群落结构及丰度的影响

运用末端限制性片段长度多态性(terminal restriction fragment length polymorphism,T-RFLP)和荧光定量PCR(real-time PCR)法,检测喀斯特灌丛生态系统中不同岩性条件下土壤固氮菌与丛枝菌根(arbuscular mycorrhizal,AM)真菌群落结构与丰度的变化,揭示岩性对灌丛生态系统土壤中固氮菌与AM真菌群落结构与丰度的影响.结果表明不同岩性条件下,土壤固氮菌与AM真菌丰度存在显著差异,其中,固氮菌与AM真菌丰度在石灰岩土壤中最大,白云岩土壤中最小,石灰岩-白云岩夹层土壤介于两者之间;同样,不同岩性土壤中固氮菌与AM真菌群落结构存在显著性差异.土壤Olsen-P、有机碳、黏粒含量与固氮菌丰度存在显著正相关关系,而土壤全氮、黏粒含量与AM真菌丰度存在显著正相关.RDA分析表明,植物均匀度影响固氮菌群落组成结构,而植物均匀度、香农多样性指数及丰富度指数影响AM真菌群落组成结构.以上的研究结果表明:岩性主要是通过影响植物与土壤养分来影响土壤固氮菌与AM真菌群落组成结构及丰度.     

随机森林算法在新疆物种丰富度影响因素研究中的应用

基于多源遥感数据及其产品,以2010年新疆地区鸟类与哺乳动物物种丰富度空间分布数据为基础,结合土地利用、植被、气候、地形等遥感数据产品,探讨了影响新疆地区鸟类和哺乳动物物种丰富度的各环境因子空间分布及其差异.通过随机森林算法对影响鸟类和哺乳动物种数的环境解释变量进行了重要性评估,同时采用探索性回归分析对物种丰富度与环境...     

滇西北与滇东南干热河谷植物群落物种多样性研究

环境变迁下生物多样性格局形成及维持机制研究是生物多样性研究的核心科学问题之一. 滇西北和滇东南两地曾在地质历史上具有相似森林植被,随着板块运移,两地出现明显环境区化,植被类型亦产生巨大变化,仅在两地干热河谷生长着相似外貌和类型的植物群落,而其物种组成和生物多样性格局有何异同尚不清晰. 该研究分别在怒江和元江干热河谷设置100 km样带,每间隔4 km布设样地,对其植被进行群落学调查. 通过计算两地不同生活型植物重要值、Alpha及Beta多样性指标,拟阐明起源相近、外貌相似的两地植被在环境变迁后群落物种组成及生物多样性的变化规律. 结果表明:①滇西北干热河谷共调查到维管植物125种(51科104属),滇东南干热河谷共调查到114种维管植物(44科102属). 滇西北乔木和灌木物种丰富度均略高于滇东南,草本反之. 滇西北乔木多度极显著高于滇东南(P<0.01),灌木多度未出现显著性差异,草本多度滇东南显著高于滇西北(P<0.05). ②从科水平分析,滇西北和滇东南乔木和草本优势科组成种类相似,但灌木优势科组成种类差异性较大. 从种水平分析发现,两地乔木优势种种类差异较大,而灌木和草本组成相似. ③滇西北植物群落Shannon-Wiener指数、Simpson指数均略低于滇东南,但无显著性差异,而Pielou指数显著低于滇东南(P<0.05). 滇西北干热河谷植物群落中优势种单一,物种分布具有聚集性;滇东南植物群落物种分布较均匀,物种多样性丰富. ④两地植物群落之间相异性系数较高,处于极不相似水平,群落间生境差异性较大,不同生活型植物Beta多样性差异极显著(P<0.001),其中以灌木物种组成的相异性最大. 研究显示,起源相近、外貌相似的滇西北与滇东南干热河谷的植物群落物种组成存在明显差异,Alpha多样性差异不明显,Beta多样性存在显著性差异,环境变迁后区域环境差异改变了植物群落结构.      

Degradation of Populus euphratica community in the lower reaches of the Tarim River, Xinjiang, China

IntroductionRiparian systems are aquatic-terrestrial ecotones withunique biotic , biophysical and landscape characteristics(Gregory, 1991 ; Naiman, 1997 ; Wiens , 2002) and areshaped by fluvial geomorphic processes . Riparian plantcommunities perform an i…     

植被演替下植物组成多样性和群落稳定性与土壤团聚体的关系

为揭示植被自然恢复过程中植物组成多样性和群落稳定性与土壤团聚体的关系,防治水土流失,提高土壤质量.通过野外调查采样,确定并分析黄土高原近150年植被演替不同阶段的植被特征与土壤团聚体数据.结果表明:该过程共有种子植物39科99属128种,优势科是菊科、蔷薇科、禾本科和豆科,优势属是蒿属,单种属是该过程植物属的主体,出现频率较高的植物有大披针薹草、胡枝子、白刺花、水栒子、青蒿、虎榛子、辽东栎、茶条枫、油松、绣线菊、狗娃花等.植物地理成分在属级水平上有11个分布区类型8个变型,温带性质明显,热带性质（R值）与温带性质（T值）的比值（R/T）随恢复年限的增加而降低,R值与R/T值显著正相关,热带成分扩散分布受到限制.植物丰富度呈单峰曲线,在恢复年限为40～70年时最高.依照不同恢复年限对群落稳定性进行排序:70>120>135>150>40>10>20>0年.R值与植物种系分化度（SD值）极显著正相关,T值与稳定性极显著正相关.>5mm粒径团聚体与受热带性质物种驱动的植物丰富度有关.>0.25mm粒径团聚体总体上与群落稳定性保持一致,均受...     

Climate change is predicted to negatively influence Moroccan endemic reptile richness. Implications for conservation in protected areas

The identification of species-rich areas and their prognosticated turnover under climate change are crucial for the conservation of endemic taxa. This study aims to identify areas of reptile endemicity richness in a global biodiversity hot spot (Morocco) under current and future climatic conditions and to investigate the role of protected areas in biodiversity conservation under climate change. Species distribution models (SDM) were performed over the distribution of 21 endemic reptiles, combined to estimate current species richness at 1?×?1 km resolution and projected to years 2050 and 2080 according to distinct story lines and ensemble global circulation models, assuming unlimited and null dispersion ability. Generalized additive models were performed between species richness and geographic characteristics of 43 protected areas. SDM found precipitation as the most important factor related to current species distributions. Important reductions in future suitable areas were predicted for 50 % of species, and four species were identified as highly vulnerable to extinction. Drastic reductions in species-rich areas were predicted for the future, with considerable variability between years and dispersal scenarios. High turnover rates of species composition were predicted for eastern Morocco, whereas low values were forecasted for the Northern Atlantic coast and mountains. Species richness for current and future conditions was significantly related to the altitude and latitude of protected areas. Protected areas located in mountains and/or in the Northern Atlantic coast were identified as refugia, where population monitoring and conservation management is needed.

     

Effects of landscape complexity on farmland birds in the Baltic States

Data on birds occurring in farmland in the Baltic States of Estonia, Latvia and Lithuania were related to the spatial organisation of farmed habitats in three different agricultural landscape types. Species richness, abundance, and diversity of farmland bird communities, as well as abundance of the most frequently observed species were positively related to the number of residual non-cropped elements within farmland, the local mixture of annual crop and grass fields, and the variety of field types. The positive association of the species richness and abundance of the farmland bird community with richness in residual habitats and crops was most prominent in open landscapes. The results suggest that, by simplifying farmland structure and making it more homogenous, EU agricultural policies will have a detrimental effect on farmland bird populations in Eastern Europe. Ways of better targeting of the agri-environment schemes are suggested.     

Development of plant communities on set-aside in England

A survey of land taken out of production from the early 1990s onwards under the European Union's set-aside policy in England was carried out in 2008, to record plant communities in set-aside of different ages, effects of distance from the field edge, sowing and soil type. Communities were classified using the Countryside Vegetation System (CVS), Ellenberg indicators and Grime CSR strategy. Species richness declined with distance from the field boundary. Annuals declined with age of set-aside. In older set-aside, perennials dominated, 40-50% of species were grasses, and grasses covered over 70% of the area. Sown areas had a higher proportion of grass species and a lower proportion of wind-dispersed species. Perennial forbs increased over time in naturally regenerated swards but decreased on sown swards. Annuals and grasses were more prevalent on light soils, with more bare ground on heavy soils. Most transects fell into CVS aggregate classes ‘tall grassland/herb’ and ‘fertile grassland’. Ellenberg fertility values decreased initially but then stabilised. Competitor scores increased, and ruderal scores declined, with age. In general, the rate of change declined with age. Although few sites had plant communities of significant conservation interest, the value of set-aside is likely to be primarily to maintain botanical diversity in intensively farmed areas, as well as providing food and habitat for fauna.     

Habitat selection by breeding waterbirds at ponds with size-structured fish populations

Fish may significantly affect habitat use by birds, either as their prey or as competitors. Fish communities are often distinctly size-structured, but the consequences for waterbird assemblages remain poorly understood. We examined the effects of size structure of common carp (Cyprinus carpio) cohorts together with other biotic and abiotic pond characteristics on the distribution of breeding waterbirds in a seminatural system of monocultured ponds, where three fish age classes were separately stocked. Fish age corresponded to a distinct fish size gradient. Fish age and total biomass, macroinvertebrate and amphibian abundance, and emergent vegetation best explained the differences in bird density between ponds. Abundance of animal prey other than fish (aquatic macroinvertebrates and larval amphibians) decreased with increasing carp age in the ponds. Densities of ducks and smaller grebes were strongly negatively associated with fish age/size gradient. The largest of the grebes, the piscivorous great crested grebe (Podiceps cristatus), was the only species that preferred ponds with medium-sized fish and was positively associated with total fish biomass. Habitat selection by bitterns and most rallids was instead strongly influenced by the relative amount of emergent vegetation cover in the ponds. Our results show that fish size structure may be an important cue for breeding habitat choice and a factor affording an opportunity for niche diversification in avian communities.     

Biodiversity,profitability, and vegetation structure in a Mexican coffee agroecosystem

We studied the relationships of bird and small mammal species richness, composition, and abundance to vegetation structure and economic profitability across a coffee intensification gradient in central Veracruz, Mexico. We conducted 2 years of point count censuses for summer resident birds, 2 years of Sherman live trapping for small mammals, and gathered vegetation structure data at 147 sampling points distributed over 16 sites spanning a cultivation intensification gradient. We calculated net annual revenue per hectare as an index of profitability from economic and management data collected during interviews with plantation owners/managers. Both the species richness and abundance of forest-affiliated birds were significantly greater in floristically and structurally diverse ‘bajo monte’ coffee and forest compared with commercial polyculture coffee, which was, in turn, significantly richer than statistically indistinguishable specialized shade and sun coffee. Mammal capture rates were extremely low at all but two sites. Forest bird species richness and abundance were explained by multiple linear regression models that included statistically significant effects of shade cover, percent of trees with epiphytes, and canopy height. We found no clear relationship between profitability and biodiversity, with biodiverse bajo monte coffee plantations ranking among the most profitable under all price scenarios. The high profitability of biodiverse bajo monte coffee systems was not dependent on the inclusion of long-term environmental costs or premium pricing systems. Our results demonstrate that high-biodiversity coffee cultivation can be compatible with high profitability, and has significant potential for conserving biodiversity in coffee-growing regions, but only as a substitute for low-biodiversity coffee cultivation, not forest.