Plant Functional Diversity and Species Diversity in the Mongolian Steppe

Background

The Mongolian steppe is one of the most important grasslands in the world but suffers from aridization and damage from anthropogenic activities. Understanding structure and function of this community is important for the ecological conservation, but has seldom been investigated.

Methodology/Principal Findings

In this study, a total of 324 quadrats located on the three main types of Mongolian steppes were surveyed. Early-season perennial forbs (37% of total importance value), late-season annual forbs (33%) and late-season perennial forbs (44%) were dominant in meadow, typical and desert steppes, respectively. Species richness, diversity and plant functional type (PFT) richness decreased from the meadow, via typical to desert steppes, but evenness increased; PFT diversity in the desert and meadow steppes was higher than that in typical steppe. However, above-ground net primary productivity (ANPP) was far lower in desert steppe than in the other two steppes. In addition, the slope of the relationship between species richness and PFT richness increased from the meadow, via typical to desert steppes. Similarly, with an increase in species diversity, PFT diversity increased more quickly in both the desert and typical steppes than that in meadow steppe. Random resampling suggested that this coordination was partly due to a sampling effect of diversity.

Conclusions/Significance

These results indicate that desert steppe should be strictly protected because of its limited functional redundancy, which its ecological functioning is sensitive to species loss. In contrast, despite high potential forage production shared by the meadow and typical steppes, management of these two types of steppes should be different: meadow steppe should be preserved due to its higher conservation value characterized by more species redundancy and higher spatial heterogeneity, while typical steppe could be utilized moderately because its dominant grass genus Stipa is resistant to herbivory and drought.     

Peculiarities of the biotopic distribution of orthoptera in the typical steppe of European Russia

The taxonomic composition, ecological and spatial distribution of orthopterans were studied in different vegetation types of the typical steppe on the left bank of the Volga River basin (Saratov Prov.). Some species showed clear selectivity with respect to specific features of the soil and vegetation, despite significant annual fluctuations in the taxonomic composition and abundance of local populations. Two groups can be distinguished: the polytopic species and those inhabiting intrazonal communities but not typical steppe habitats. The orthopteran complexes of the zonal and halophytic habitats show a relatively high similarity; they differ well from those of mesophytic plant communities, restricted to the lower mesorelief areas. Intrazonal habitats with mesophytic conditions comprise almost 45% of the species diversity of orthopterans in the typical steppe subzone, and reveal the greatest diversity of life forms of these insects. The data obtained are of interest for monitoring the successive changes in steppe ecosystems affected by both climatic and anthropogenic factors.     

草地群落放牧干扰梯度β多样性研究

放牧过程通过牲畜的啃食、践踏作用干扰草场环境,使草地群落的物种组成发生变化,植物种群的优势地位发生更替。结果表明,随放牧干扰强度加重,从盐湿化草甸到典型草原,群落植物种丰富度呈下降趋势。β多样性测度结果显示,盐湿化草甸和羊草杂类草草甸群落物种变化的中度干扰出现在轻牧→中牧阶段,并在整个放牧干扰进程中,表现较低的稳定性;草甸草原和典型草原群落出现在中牧→重牧阶段;而荒漠草原物种变化表现出高度的稳定性,从轻牧到过牧物种替代仅1～3种。各群落放牧干扰植物多样性的稳定性次序是:荒漠草原>典型草原≥草甸草原>盐湿化草甸.     

Plant cover associated with aboveground net primary productivity (ANPP) mediates insect community composition in steppes of Northwest China

Temperate steppe is one of the most important natural habitats for the conservation of arthropod and bird biodiversity across the Eurasian Tectonic Plate. Since 1950, fragmentation of the steppe habitat has caused a loss of biodiversity and degradation of the species communities found in natural steppe. Therefore, in this study, both plants and insects were sampled at 56 sites in the steppe biome of northwestern China to explore the effects of plant community on insect community composition and diversity. The insect community structure varied in the four different steppe types (meadow steppe, typical steppe, desert steppe, and steppe desert). Plant cover (diversity) was an important driving force, which could enhance number of families and abundance of an insect community. Aboveground net primary productivity and water content of plants had no significant effects on insect community, although the plant community as a whole did mediate insect composition and community structure. Future research should explore the ecological role of particular functional groups in plant and insect communities. Supplemental sowing to improve plant diversity in steppe habitat may be another strategy to enhance biodiversity and achieve sustainable management.     

新疆东部天山蝶类多样性及其垂直分布

2006-2008年研究了新疆东部天山蝶类多样性和垂直分布.结果表明:研究区域内共记录蝴蝶7科43属63种,占新疆已记录蝶类种数的24.80％,区系组成主要是古北种,占73％;其次是广布种,占27％,没有发现东洋种.其中蛱蝶科的物种数最多,为11属19种,蚬蝶科的物种数最少,只有1属1种.按海拔将生境分为5个垂直自然带,包括低山灌木草原带、山地森林草原带、亚高山草甸带、高山草甸带、垫状植被带.蝶类物种数和个体数排序为亚高山草甸带＞山地森林草原带＞低山灌木草原带＞高山草甸带＞垫状植被带.采用Shannon-Wiener指数和G-F指数对蝶类物种和科、属的多样性进行了分析评价,结果显示亚高山草甸带的蝶类多样性最为丰富,其次是山地森林草原带和低山灌木草原带,而高山草甸带和垫状植被带的蝶类多样性相对较低,物种和科、属多样性分析结果均一致.蝶类垂直分布明显,物种数和个体数随海拔变化的趋势类似,均为先增加后下降.蝶类区系成分随着海拔升高发生改变,广布种的比例逐渐降低,高山草甸带和垫状植被带只有古北种分布.研究结果显示,生境改变对蝴蝶群落影响明显,保护生境是保护蝴蝶生存的最主要措施.     

内蒙古荒漠草原37种植物氮与灰分含量的特征

本文报告了内蒙古荒漠草原地区37种植物氮、硅与灰分含量的组成特征。结果表明,荒漠草原区植物的平均含硅量(1.019%),灰分含量(12.85%)都高于草甸草原与典型草原,而其含氮量(2.16%)都低于草甸草原与典型草原。在内蒙古草原区,植物化学元素组成呈现了地带性分异的特征。     

Changes in the orthopteran population over plant cover restoration in the fallow lands of the European steppe

A comparative analysis of the Orthopteran population in virgin and fallow lands of the European steppe has allowed finding out the colonization sources of the fallow lands: the inhabitants of the mesophytic intrazonal plant communities, including the formations of steppe bushes and polytopic species living in intact and disturbed steppe habitats have been found there. It has been shown that the structure of the Orthopteran population in the fallow lands in determined more by the composition of their plant cover than by the actual age of fallow lands or their zonal position. Fundamental changes in the structure of Orthopteran population are associated with the replacement of tall weed communities by an herb-grass cover; the faunistic similarity between the old fallow lands and zonal plots therewith increases. The abundance of Orthopteras in the fallow lands increases southward, while in zonal communities a reverse tendency is observed. The Orthopteran populations in the fallow lands of all the subzones are characterized by higher diversity and evenness if compared to zonal biotopes. A wide distribution of fallow lands with weed cover turns out to increase the faunistic and ecological diversity of the Orthopteran populations in the European steppe.     

内蒙古荒漠草原37种植物氮与灰分含量的特征

本文报告了内蒙古荒漠草原地区37种植物氮、硅与灰分含量的组成特征,结果表明,荒漠草原区植物的平均含硅量(1.019%),灰分含量(12.85%)都高于草甸草原与典型草原,而其含氮量(2.16%)都低于草甸草原与典型草原。在内蒙古草原区,植物化学元素组成呈现了地带性分异的特征。     

The relationship between species richness and productivity in four typical grasslands of northern China

The relationship between plant species richness and primary productivity has long been acentral topic in biodiversity research.In this paper,we examine the relationship between species richness and productivity in four typical grasslands of Northern China at different spatial scales.At the community scale,a positive correlation was found for six of seven communities.A unimodal pattern was found only for one community (Stipa glareosa community),while at a large scale (vegetation type or landscape/region),the relationship was also found significantly positive.Species richness ranged from 4 to 35 species,and community aboveground productiand aboveground productivity were found in alpine meadow,followed by meadow steppe,typical steppe and desert steppe.     

The latitude-zonal and spatial-successional trends in the distribution of yeasts

The distribution of yeasts in natural habitats is analyzed in the different nature zones of the former USSR (from tundra to desert) using the results of long-term research. Yeast community structure is changing in parallel to different stages of plant debris decay as well as to latitude-zonal gradient. These changes are not fluctuating but trend ones. As mineralization of plant debris proceeds the availability of sugars decreases and habitat become more extremal for yeasts which are typical saccharolytics. It causes decrease in species abundance and species diversity. At the same time in zonal gradient the most significant changes take place in the relative abundance of dominant species, genera or higher taxonomic groups. The thermotolerant species occurred more often in the southern regions while psychrophilic species dominate in the north. Soil yeast communities become more polytrophic in the north latitudes where mineralization of organic matter is rather low. Species inhabiting climatic pessimum areas usually form chlamidospores.     

Floristic diversity of meadow steppes in the Western Siberian Plain: effects of abiotic site conditions,management and landscape structure

Temperate grasslands have suffered from severe habitat loss and degradation worldwide. In Russia, vast areas of forest-steppe grasslands have been converted to cropland during Soviet times, whilst remaining grasslands were often intensively grazed. Contrastingly, the collapse of the Soviet Union have resulted in a massive reduction in livestock numbers and cessation of management. Albeit relatively large natural grassland areas remained in the Western Siberian Plain, their present condition is poorly studied. We analysed plant species composition, functional structure and richness of grassland communities and tested for the effect of local factors (management, abiotic site conditions) and landscape factors (patch size, proportion of land cover types) on diversity patterns. Abiotic site conditions, mainly soil moisture and salinity, differentiated distinct community types. Overall, species richness was highest in meadow steppe communities with lower soil moisture and salinity. Grazing intensity and litter accumulation due to cessation of management were significant negative related to species richness and shaped the functional structure. At the landscape scale, diversity in meadow steppe grasslands was higher in forest-grassland mosaics and in small remnants isolated in a matrix of cropland. Our findings highlight that meadow steppes suffered massively under the historical habitat loss and high grazing pressure. Small species-rich remnants are evidence of the former extent of meadow steppe habitats in agricultural landscape, but are likely threatened by an extinction debt. Low intense, irregular mowing maintained species-rich meadow steppe in forest- grassland mosaics, but currently such practices are declining.     

中昆仑山北坡及内部山原的植被类型

 中昆仑山西始乌鲁乌斯河,东迄安迪河,东西迤逦600余公里,平均海拔高度6000m。该区有野生种子植物52科,211属,398种。植物区系以种类成份单纯、地理成份复杂为特征。北坡中山带和高山带下部年降水量300—500mm,草原带发育完整,尤以中段的策勒山地草原发育最好。草原带以上高寒荒漠不存在,高寒草甸则有一定发育。中昆仑山北坡植被类型的垂直带谱是：1)山地荒漠,自山麓线多在2200—2500m,个别在3000m;2)山地荒漠草原在3000—3200m;3)山地真草原在3200—3600m;4)高寒草原在3600—3800m(阳坡上升到4200m以上);5)高寒草甸在3800—4200m;6)高山垫状植被仅见于东段山地和高寒草甸复合分布;7)高山流石坡稀疏植被在4200—5000m。中昆仑山内部山原极端寒冷干旱,多为砾漠所占据,高寒荒漠和高寒荒漠草原呈片状星散分布。     

Responses of Plant Community Composition and Biomass Production to Warming and Nitrogen Deposition in a Temperate Meadow Ecosystem

Climate change has profound influences on plant community composition and ecosystem functions. However, its effects on plant community composition and biomass production are not well understood. A four-year field experiment was conducted to examine the effects of warming, nitrogen (N) addition, and their interactions on plant community composition and biomass production in a temperate meadow ecosystem in northeast China. Experimental warming had no significant effect on plant species richness, evenness, and diversity, while N addition highly reduced the species richness and diversity. Warming tended to reduce the importance value of graminoid species but increased the value of forbs, while N addition had the opposite effect. Warming tended to increase the belowground biomass, but had an opposite tendency to decrease the aboveground biomass. The influences of warming on aboveground production were dependent upon precipitation. Experimental warming had little effect on aboveground biomass in the years with higher precipitation, but significantly suppressed aboveground biomass in dry years. Our results suggest that warming had indirect effects on plant production via its effect on the water availability. Nitrogen addition significantly increased above- and below-ground production, suggesting that N is one of the most important limiting factors determining plant productivity in the studied meadow steppe. Significant interactive effects of warming plus N addition on belowground biomass were also detected. Our observations revealed that environmental changes (warming and N deposition) play significant roles in regulating plant community composition and biomass production in temperate meadow steppe ecosystem in northeast China.     

Shading out species richness: edge effect of a pine plantation on the Orthoptera (Tettigoniidae and Acrididae) assemblage of an adjacent dry grassland

Edge effects are increasingly recognised as a threat to interior species, but the influence of edges on open habitats has rarely been addressed so far. We investigated the diversity pattern of the Orthoptera fauna across a habitat edge between a pine plantation and a natural steppe ecosystem. Thirty pitfall traps were positioned along a transect line from 80 m in the forest to 208 m in the grassland at 10 fixed distances from the edge. The orthopteran assemblage of the pine plantation was depauperate in species and individuals and, with a few exceptions, lacked steppe species. We found no increase in species richness at the forest–grassland edge. In the grassland, Orthoptera species numbers increased steadily with increasing distance from the forest edge. Two-phase regression analysis revealed a traceable edge effect up to about 30 m into the grassland. This effect was exclusively caused by an increase in acridid species numbers, while tettigoniid species numbers showed no clear relation to edge distance. Correlation analysis of the habitat variables suggested that this pattern is a result of irradiance and soil temperature sums. Since acridids show species-specific temperature requirements for their development, shading of the soil surface prevents a number of species from completing their life cycle. We suggest that present trends of shrub encroachment and eutrophication of dry grassland habitats in eastern Austria are serious threats for a large part of the orthopteran fauna.     

长期围封对疏勒河源区高寒草甸地表节肢动物多样性的影响

围封会促进退化高寒草甸植被和土壤环境恢复,长期围封也会导致生物多样性及其功能下降,影响高寒草甸生态系统的稳定,但这种影响会随着季节和生境条件变化而异。为了探究不同退化程度高寒草甸地表节肢动物群落变化对围封禁牧的响应,利用陷阱法调查了疏勒河源区沼泽化草甸、草甸和草原化草甸3种不同退化梯度高寒草甸围封禁牧和自由放牧处理下地表节肢动物群落结构变化。结果表明：围封禁牧对高寒草甸地表节肢动物群落组成及多样性的影响随生境条件不同而异。禁牧降低了沼泽化草甸地表节肢动物的物种丰富度,而提高了草甸和草原化草甸地表节肢动物的物种丰富度;围封禁牧对沼泽化草甸地表节肢动物群落结构影响较小,显著降低了草甸生境地表节肢动物活动密度、提高了地表节肢动物多样性和均匀度,相反,禁牧显著提高了草原化草甸生境地表节肢动物活动密度、降低其多样性和均匀度;豹蛛属1种是高寒草甸主要的地表节肢动物类群（相对多度为67.0%）,高寒草甸土壤水分有效性等生境条件不同影响了豹蛛属1种对围封禁牧的响应模式,进而影响了地表节肢动物群落结构变化。总之,高寒草甸退化程度影响了地表节肢动物多样性对禁牧和放牧的响应模式,沼泽化草甸适度放牧有利于提高地表节肢动物多样性及其功能。     

塔里木荒漠河岸林异质生境物种多样性比较与其测度指标筛选及评价

选择合适的物种多样性测度指标与多样性指数是进行群落多样性研究的基础工作。依据塔里木河上游荒漠河岸林样地调查资料,分别采用重要值、盖度和多度为测度指标比较了反映群落物种丰富度、多样性、均匀度和优势度12种多样性指数与异质生境群落多样性特征,并对多样性指数进行了相关分析与评价。结果表明,荒漠河岸林异质生境群落物种组成种类差异明显,轮南镇胡杨群落物种丰富度与多样性指数最高,水工三连灰胡杨群落多样性最低,土壤水盐的空间异质性是引起荒漠植被空间分布与群落多样性差异的主导因子。表征荒漠群落多样性以重要值和盖度为测度指标优于多度指标,其中以重要值为测度指标来反映群落多样性更为合理。相关与主成分分析表明,均匀度与多样性指数间的相关性高于丰富度与多样性指数,且多样性指数受均匀度、优势度指数受丰富度影响较大,反映出荒漠河岸林群落多样性主要决定于物种分布的均匀程度。12种多样性指数中Margalef丰富度指数（Ma）、Shannon-Weiner多样性指数（H）与Simpson多样性指数（D）能客观真实地反映异质生境荒漠植物群落多样性。同时,针对高度生境异质性的荒漠植物群落,还应综合考虑群落物种组成与生境特征,选择合适的多样性指数组合可更客观地反映荒漠河岸林群落多样性变化。     

Terrestrial bugs (Heteroptera) in high mountains of the Suntar-Khayata Range (Eastern Yakutia)

Thirty-nine species of bugs, representing meso-and xerophilic inhabitants of open tundra, meadow, and steppe landscapes, were collected within the altitude range of 1260–1850 m above sea level in the upper Kyubyume River basin (63°13′N, 139°36′E, the Indigirka River basin). In the sub-golets sparse forest zone (up to 1550 m), 37 species were recorded, the dominant form being Chlamydatus pullus. The bugs were rare in most of the habitats; their species richness and abundance increased distinctly only on the south-facing slopes, reaching the maximum in the cryophytic steppe. The specific features of these complexes manifested themselves in the prevalence of Capnoda nigroaenea, a xerophilic species of alpine mountain steppes. The rest of the dominants comprised the ecologically flexible Emblethis brachynotus, Chlamydatus pullus, and Galeatus spinifrons. In the goletstundra zone, 8 species were found, half of them being arctic forms (Calacanthia trybomi, Orthotylus artemisiae, Ch. wilkinsoni, and Ch. opacus). Ch. wilkinsoni was the most common species. The species composition of bug groups in the dry lichen-dryad communities within this zone resembled that of similar communities of zonal tundra, whereas the humid habitats remained unpopulated, unlike their plain analogues. Comparison of the heteropteran fauna of mountain tundras in different regions of the Verkhoyansk-Kolyma mountain country attests to significant variations of its species composition. The possible reasons for these differences are discussed.     

内蒙古高原针茅草原群落土壤水分和碳、氮分布的小尺度空间异质性

用地统计学的方法,研究比较了内蒙古高原4类地带性针茅草原群落,贝加尔针茅（Stipa baicalensis)群落,大针茅（S.grandis)群落,克氏针茅（S.krylovii)群落和小针茅（S.kelemenzii)群落0-20cm土壤水分和碳,氮的小尺度空间异质性特征,结果表明;4类群落土壤水分,有机碳和全氮均表现出显著的小尺度空间结构特征。自相关尺度为1.91m-10.81m,结构性方差占样本方差的35.31%-99.74%。从贝加尔针茅群落到小针茅群落空间自相关的尺度逐渐增大,纹理有逐渐变粗的趋势,土壤水分,碳和氮的小尺度空间格局共同作用于群落的生态学过程,即土壤水分格局→植物种群格局（基本斑块的大小）→土壤碳空间格局→土壤氮空间格局,同时,由于生态学过程的反馈作用,土壤氮空间格局→种群格局→土壤水分格局,土壤属性空间自相关尺度的改变可能是导致群落演替的驱动力,草原退化可能与土壤异质性尺度的改变相关。     

Gradients in the number of species at reef-seagrass ecotones explained by gradients in abundance

Gradients in the composition and diversity (e.g. number of species) of faunal assemblages are common at ecotones between juxtaposed habitats. Patterns in the number of species, however, can be confounded by patterns in abundance of individuals, because more species tend to be found wherever there are more individuals. We tested whether proximity to reefs influenced patterns in the composition and diversity ('species density' = number of species per area and 'species richness' = number of species per number of individuals) of prosobranch gastropods in meadows of two seagrasses with different physiognomy: Posidonia and Amphibolis. A change in the species composition was observed from reef-seagrass edges towards the interiors of Amphibolis, but not in Posidonia meadows. Similarly, the abundance of gastropods and species density was higher at edges relative to interiors of Amphibolis meadows, but not in Posidonia meadows. However, species richness was not affected by proximity to reefs in either type of seagrass meadow. The higher number of species at the reef-Amphibolis edge was therefore a consequence of higher abundance, rather than species richness per se. These results suggest that patterns in the composition and diversity of fauna with proximity to adjacent habitats, and the underlying processes that they reflect, likely depend on the physiognomy of the habitat.     

A comparison of flooded forest and floating meadow fish assemblages in an upper Amazon floodplain

Matched sets of gillnets of different mesh-sizes were used to evaluate the degree to which contiguous and connected flooded forest and floating meadow habitats are characterized by distinct fish faunas during the flooding season in the Peruvian Amazon. For fishes between 38–740 mm standard length ( L _S) (the size range captured by the gear), an overriding pattern of faunal similarity emerged between these two habitats. The mean species richness, diversity, abundance, fish mass, mean and maximum L _S, and maximum mass did not differ significantly between flooded forest and floating meadows. Species abundances followed a log-normal distribution in which three species accounted for 60–70% of the total abundance in each habitat. Despite these similarities, multivariate analyses demonstrated subtle differences in species composition between flooded forest and adjacent floating macrophytes. In addition, the absolute number of species was higher in flooded forest, reflecting a higher percentage of rare species. The day–night species turnover was found to be greater in flooded forests than floating meadows. Further, nocturnal samples had higher abundances and greater species richness than diurnal samples in both habitats. Differences in habitat structural complexity between flooded forest and floating meadows may result in a higher abundance and species richness of day-active species in floating meadows.