Niche characteristics of rodents by diverse disturbance in Alashan desert, Inner Mongolia, China

Four diverse disturbance types, namely, farmland, rotationally grazed grassland, overgrazed grassland and forbidden grazing grassland, were identified in the Alashan desert region of Inner Mongolia. Rodents were sampled in April, July and October in 2002 and 2003 using the trap-day method. Their spatial and temporal niches among the four disturbance types were assessed using the Shannon-Wiener niche breadth index and the Pianka niche overlap index. The Shannon-Wiener niche breadth index was the highest for Allactaga sibirica and Meriones meridianus (0.925 and 0.908, respectively), intermediate for Cricetulus eversmanni, Phodopus roborovskii and Citellus dauricus (0.789, 0.782 and 0.711, respectively), and lowest for Cardiocranius paradoxus (0.003). The Pianka niche overlap indices of six-paired species were the highest and varied from 0.900 to 1.000, suggesting their spatial niche overlapped almost completely. Conversely, the spatial niche overlap index for Meriones unguiculatus, Cardiocranius paradoxus, and Salpingotus kozlovi was zero, thus indicating a complete absence of competition among them. In addition, the temporal niche breadth and overlap indices varied greatly in relation to disturbance types and season. The level of temporal niche overlap in spring and autumn was low while in summer it was high. For all disturbance types and for each season, the temporal niche overlap index of Meriones meridianus and Cricetulus barabansis was always highest but for Meriones unguiculatus and Salpingotus kozlovi always lowest. __________ Translated from Acta Ecologica Sinica, 2005, 25(10): 2,637–2,643 [译自: 生态学报]     

药用柴胡属植物产地与化学成分相关性研究

从柴胡属植物品种入手,着重介绍药用柴胡属植物的生境分布、不同产地环境因子与柴胡化学成分研究进展,并为将来控制柴胡质量,解决柴胡资源有效途径提供方案.     

Biological availability and humic properties of dissolved organic carbon in Lake Balaton (Hungary)

The nursery role of the Mondego estuary for marine fish species was studied between June 2003 and May 2004. The spatial and temporal distribution and abundance patterns of 0-group Dicentrarchus labrax (Linnaeus, 1758), Platichthys flesus (Linnaeus, 1758) and Solea solea (Linnaeus, 1758) were analyzed based on monthly sampling surveys in five stations along the estuarine gradient. Fishing took place during the night at low water of spring tides, using a 2 m beam trawl. The spatial patterns of estuarine colonization were different according to species. D. labrax showed a wider distribution, but the main nursery ground was the same as for S. solea. Highest densities of S. solea juveniles were found in oligohaline areas, with muddy bottoms and high benthic invertebrates availability, while P. flesus occurred mainly in the sandy uppermost areas. D. labrax was found in both these areas. Fish abundance in the estuary mainly reflected seasonal changes.     

Urbanization effects on different biological organization levels of an estuarine polychaete tolerant to pollution

Estuarine species exposed to diffuse contaminants might trigger either positive or negative feedbacks in many biological scales. Their life history traits performing at different biological organization levels could propose an organism as a useful indicator of environmental pollution, mainly addressed as sensitive or tolerant species. To track the effects of contaminants from the molecular to the population level of the polychaete Laeonereis acuta we utilize a framework of biomarkers. For this purpose we assessed the L. acuta frequency of micronuclei at the molecular level, the body size and biomass at individual level, and the production-to-biomass ratio at population level in five urbanized and five non-urbanized estuaries in southern Brazil. L. acuta had significantly varying positive and negative feedbacks between urbanized and non-urbanized estuaries at multiple biological scales. These generalized effects in all biological organization scales indicate a pollution impact on the polychaete. The main responses accounted for individuals becoming lengthy and weighty, but with molecular damage. The L. acuta allocation of energy to body enlargement in polluted environments, and a consequent reduced population turnover, contradicts the expected from an opportunist species. The damages in DNA and the internal strategies of individuals, as antioxidant defense mechanisms, could favor resistance of the population and tolerance to pollutants. All of these characteristics induce bioaccumulation and could cause bottom-up pollution transfer compromising the estuarine food web. These results, ascertain that L. acuta could be considered as a tolerant species, instead of an opportunistic, and as a useful indicator of environmental pollution in estuaries.     

Characterization of moorland vegetation and the prediction of bird abundance using remote sensing

Aims To characterize and identify upland vegetation composition and height from a satellite image, and assess whether the resulting vegetation maps are accurate enough for predictions of bird abundance. Location South‐east Scotland, UK. Methods Fine‐taxa vegetation data collected using point samples were used for a supervised classification of a Landsat 7 image, while linear regression was used to model vegetation height over the same image. Generalized linear models describing bird abundance were developed using field‐collected bird and vegetation data. The satellite‐derived vegetation data were substituted into these models and efficacy was examined. Results The accuracy of the classification was tested over both the training and a set of test plots, and showed that more common vegetation types could be predicted accurately. Attempts to estimate the heights of both dwarf shrub and graminoid vegetation from satellite data produced significant, but weak, correlations between observed and predicted height. When these outputs were used in bird abundance–habitat models, bird abundance predicted using satellite‐derived vegetation data was very similar to that obtained when the field‐collected data were used for one bird species, but poor estimates of vegetation height produced from the satellite data resulted in a poor abundance prediction for another. Conclusions This pilot study suggests that it is possible to identify moorland vegetation to a fine‐taxa level using point samples, and that it may be possible to derive information on vegetation height, although more appropriate field‐collected data are needed to examine this further. While remote sensing may have limitations compared with relatively fine‐scale fieldwork, when used at relatively large scales and in conjunction with robust bird abundance–habitat association models, it may facilitate the mapping of moorland bird abundance across large areas.     

Gradients of life-history variation: an intercontinental comparison of fishes

Multivariate analysis identified atwo-dimensional continuum of life-historyvariation among 301 fish species from Europe,North America, South America and the Atlanticand Pacific coasts of North America. The firstaxis was associated with larger body size,higher fecundity, delayed maturation, fewerreproductive events, and shorter breedingseason on one end and small size, lowfecundity, early maturity, multiplereproductive events per year, and prolongedbreeding season on the other. The second axiscontrasted fishes having larger eggs and moreparental care against fishes with the oppositesuite of traits.Phylogenetic affiliations of species wereapparent in the general patterns of ordinationof species within orders, indicatingevolutionary divergences in life-historypatterns. In fact, partitioning the variance oflife-history traits showed that taxonomic orderand latitude were the most important factorsand geographic region and habitat the least.Despite phylogenetic constraints, basiclife-history patterns showed consistencybetween distantly geographical regions,latitudinal ranges and basic adult habitats,indicating convergences in life-historypatterns. Although the basic life-historypatterns seemed repeatable among distantlyrelated taxa, geographical and latitudinalaffiliations were apparent. Species from SouthAmerica are skewed toward the opportunisticendpoint, whereas North American marine speciesare skewed toward the periodic endpoint of thetrilateral continuum model. Most of the fishspecies from South American data set came fromfluctuating environments, so an opportunisticstrategy of early maturation and continuousspawning permits efficient recolonization ofhabitats over small spatial scales. Incontrast, most species in the North Americanand European data sets came from seasonalhabitats that are nonetheless more hydrologicalstable, so a periodic strategy of delayingmaturation to attain large clutches enhancesadult survivorship during suboptimalenvironmental conditions and recruitment whenearly life stages encounter suitableenvironmental conditions. Similarly,latitudinal affiliations were also observed:opportunistic strategists more common intropical latitudes and periodic strategistsmore common in temperate and Arctic latitudes.     

Relative sea‐level change regulates organic carbon accumulation in coastal habitats

Because coastal habitats store large amounts of organic carbon (C_org), the conservation and restoration of these habitats are considered to be important measures for mitigating global climate change. Although future sea‐level rise is predicted to change the characteristics of these habitats, its impact on their rate of C_org sequestration is highly uncertain. Here we used historical depositional records to show that relative sea‐level (RSL) changes regulated C_org accumulation rates in boreal contiguous seagrass–saltmarsh habitats. Age–depth modeling and geological and biogeochemical approaches indicated that C_org accumulation rates varied as a function of changes in depositional environments and habitat relocations. In particular, C_org accumulation rates were enhanced in subtidal seagrass meadows during times of RSL rise, which were caused by postseismic land subsidence and climate change. Our findings identify historical analogs for the future impact of RSL rise driven by global climate change on rates of C_org sequestration in coastal habitats.     

蝗虫生境监测方法研究进展

蝗虫是一种能对农业生产带来毁灭性打击的害虫。预测、监测蝗虫的发生、发展对于防治蝗虫、减轻蝗灾具有重要意义。在分析蝗虫的发生和消长与其生存环境的关系基础上,概述了以往蝗虫发生、发展预测、监测的主要方法。然后,从监测蝗虫生境采用的指标、卫星数据、算法等方面进一步阐述了运用现代遥感、地理信息系统技术监测蝗虫生境、预测蝗虫发生、发展的理论基础和最新进展;最后,结合现代对地观测技术、网络、快速计算和模拟等技术的发展探讨了蝗虫生境监测的发展方向。     

Species richness and endemism of birds in Bioko

The status of 50 taxonomically unique bird taxa found in Bioko is described. A complete updated species list for birds in Bioko is also given. Notes on habitat occupied and altitudinal distribution of each species as well as information on their general abundance is also included. Species distributions may have been affected by habitat modifications brought about by humans but most taxonomically unique forms are found in the montane areas. Comparisons are made with the neighbouring Mount Cameroon area.     

陕北黄土丘陵沟壑区坡沟立地环境下幼苗的存活特征

幼苗是植被恢复演替的基础, 在生态系统中具有非常重要的作用。为了探索黄土丘陵沟壑区坡沟立地环境下幼苗的存活特征, 在陕西省安塞县宋家沟和纸坊沟流域设置15个固定样地进行定点动态监测, 运用单因素方差分析法和系统聚类分析法对不同立地环境下的幼苗密度和幼苗存活率进行了分析。结果表明: 1)不同坡沟立地环境下, 幼苗存活特征差异明显, 整体表现为阳坡幼苗密度较小而存活率较高, 阴坡幼苗密度较大但存活率较低。2)细裂叶莲蒿(Artemisia gmelinii)、菊叶委陵菜(Potentilla tanacetifolia)、阿尔泰狗娃花(Heteropappus altaicus)等物种具有较高的幼苗存活率, 在生存竞争中幼苗是以“质”取胜; 而猪毛蒿(Artemisia scoparia)、中华苦荬菜(Ixeris chinensis)、阴行草(Siphonostegia chinensis)等物种具有较高的幼苗密度, 在生存竞争中是以“量”取胜。3)同一物种在坡沟立地环境下表现出不同的存活曲线, 不同物种在不同立地环境下也可呈现同一存活曲线; 细裂叶莲蒿、菊叶委陵菜、长芒草(Stipa bungeana)、阿尔泰狗娃花、兴安胡枝子(Lespedeza davurica)等物种, 幼苗不仅在雨季存活能力强且具有较强的越冬能力; 猪毛蒿、香青兰(Dracocephalum moldavica)、臭蒿(Artemisia hedinii)等物种在雨季前幼苗存活能力较强, 但冬季存活能力弱。4)坡面不同微环境下幼苗存活特征也存在差异, 即微环境的改变在一定程度上影响着幼苗的生长、存活和越冬。因此, 在黄土丘陵沟壑区应根据物种幼苗存活特性对幼苗进行适当的抚育管理, 这将有利于幼苗的建植和植被更新。