直翅目昆虫对不同石漠化草地生境的指示作用

在贵州黔西南州晴隆县孟寨小流域,根据不同石漠化治理(即不同人为干扰条件下)选择4种草地生境类型。这4种生境为桃园宽叶雀稗套种人工牧草地、皇竹草套种人工牧草地、荒坡灌丛草地、自然草地,每个生境设置3个样方。于2015年4月至9月,以网捕法对直翅目昆虫多样性及其对不同草地生境的指示作用进行调查,共捕获6822头直翅目昆虫,总计9科17属22种。调查结果表明,小稻蝗(Oxya hyla intricate)(38.60%)及短额负蝗(Atractomorpha sinensis)(18.42%)为该地区的优势种,另有12种常见种以及8种稀有种。其中自然草地多样性指数最高(2.323),其他的群落指数也较高,表明该生境物种最为丰富,直翅目昆虫群落结构最为复杂。其次是荒坡灌丛草地和皇竹草套种人工牧草地,桃园宽叶雀稗套种人工牧草地的多样性指数最低。利用指示值法筛选不同生境的特征指示种,结果表明,宽叶雀稗套种人工牧草地生境中有山稻蝗(O.agavisa)等3种指示生物。荒坡灌丛草地生境中有疣蝗(Trilophidia annulata)等3种指示物种。自然草地生境中有青脊竹蝗(Ceracris nigricornis)等4指示物种。皇竹草套种人工牧草地没有明显的指示物种,但存在丰富的监测物种。

国内外草本植物在沙化草地生境应用的研究进展

全面梳理了国内外沙化草地生境草本植物生长适应性、草本植物群落建植和生态修复效应3方面的研究进展,并通过对比进行了综合分析。结果表明:国外对沙化草地生境草本植物群落的研究起步较早,在野生草本植物在沙化草地生境中的引种应用、植物群落设计、群落构建机理、生物多样性等方面具有较为充分的研究成果;国内对沙化草地生境草本植物群落的相关研究起步较晚,且多以一二年生草本植物、牧草为主,研究更多侧重在单株草本植物对土壤、水分等的修复效应,缺少草本植物群落的景观应用方面的研究。在既有研究综述基础上,提出了草本植物在沙化草地生境应用研究中亟待深入的4个方面问题:关注野生草本植物在沙化草地生境中的引种与应用研究;演绎不同模式的草本植物群落组合与配置研究;探究草本植物群落的正向演替机制研究;加强草本植物群落生态服务功能评价研究,以期为沙化草地生境草本植物应用研究提供思路和方向,推进未来沙化草地生境的生态修复研究工作。

β-diversity Patterns of Plant Community in Fragmented Habitat in a Degenerated Meadow in Songnen Plain,China

A number of isolated islands of Leymus chinensis ＋ herbosa community were investigated in fragmented habitat islands, by Braun-Blanquet field survey approach, in a degenerated meadow in the Songnen Plain, China in 2007. These islands were classified as large, medium, and small scales on the basis of the island area （100-1000m2, large island; 50-100m2, middle island; 10-50m2, small island）. Each scale of the investigation involved eight islands. The responses ofβ-diversity patterns of plant taxon to the habitat fragmentation at local community and metacommunity levels were analyzed on different scales of 24 isolated islands. The results indicated that at the local community level, there were 57 species belonging to 20 families and 49 genera in large islands, 49 species belonging to 16 families and 40 genera in middle islands, and 27 species belonging to eight families and 23 genera in small islands, β-diversity indexes for species, genus and family in large, middle, and small islands varied greatly, and the highest value of the indexes was not noted in the largest island. However, the average of the data obtained at the three scales showed that across large islands, Whittaker indexes were low and Bray-Curtis similarity indexes were high, while across small islands, Whittaker indexes were high and Bray-Curtis similarity indexes were low. At the metacommunity level, Whittaker indexes for species and genus showed a great significantly negative double logarithmic correlation （p〈0.01） with the island area, whereas the Bray-Curtis indexes for species, genus and family showed a great significantly positive double logarithmic correlation （p〈0.01） with the island area. At both local community and metacommunity levels, tumovers of species and genus could respond more sensitively to spatial changes of plant diversity patterns than that of family. Hence, the species and the genus could be used for the analysis offl-diversity patterns of plant community.

Microhabitat Effect on Iron Distribution and Transfer in Carex pseudocuraica in Sanjiang Plain Wetlands

Ten clonal units of Carex pseudocuraica growing in four different microhabitats (perennial flooded ditch water,perennial flooded ditch sediment,seasonal flooded ditch sediment and perennial flooded soil) of the Sanjiang Plain,Northeast China,were collected randomly for phenotypic plasticity analysis.Iron content,chemical and physical properties of substrates and the total Fe of nine plant modules were measured as well.The results show that the performance of the C.pseudocuraica is affected by the microhabitat,with the greatest performance score in perennial flooded ditch water,and the lowest in perennial flooded soil.The biomass allocation indexes indicate that much more mass is allocated to stems and roots to expand colonization area.The distribution of the total Fe in plant modules appears as pyramids from the tip to the root,while marked differences are observed in the distribution proportion of stems,tillering nodes and roots that are allometrically growing.Iron transfer from substrates to the plant is mainly controlled by the substrate type.The differences of iron distribution and transfer in the plant in different microhabitats are attributed to the iron contents of the substrates as well as the phenotypic plasticity of the plant.

Responses of Grassland Net Primary Productivity to Environmental Variables in Northern China

Various environmental factors affect net primary productivity （NPP） of grassland ecosystem. Extensive reports on the effects of environmental variables on NPP can be found in literature. However, the agreement on the relative importance of various factors in shaping the spatial pattern of grassland NPP has not yet been reached. Here a grassland in situ NPP database comprising 602 samples in northern China for 1980-1999 was developed based on a literature review of published biomass and forage yield field measurements. Correlation analyses and dominance analysis were used to quantify the separate and combined effects of environmental variables （climate topography and soil） on spatial variation in NPP separately. Grassland NPP ranged from 4.76 g C m-2a-1 to 975.94gCm-2a-1, showing significant variations in space. NPP increased with annual precipitation and declined with annual mean temperature significantly. Specifically, precipitation had the greatest impact on deserts, followed by steppes and meadows. Grassland NPP decreased with increasing altitude because of water limitation, and positively correlated with slope, but weakly correlated with aspect. Soil quality showed positive effects on NPP. Annual precipitation was the dominant factor affecting the spatial variability of net primary productivity, followed by elevation.