Long-term trends in the abundance of Mediterranean wetland vertebrates: From global recovery to localized declines

Biodiversity loss is unevenly distributed in space and time. Species have reached critically low population sizes in some areas, and remain abundant in others. Similarly, some species may benefit from successful conservation plans, while others still experience severe population depletions driven by negative impacts of human activities. Although several indicators have been proposed to measure the fate of biodiversity, they are generally only implemented globally so their relevance for regional assessment is still unclear. Here, we calculated the first regional trend in the Living Planet Index for the Mediterranean wetlands (Med LPI), an indicator that summarizes the fate of global biological diversity based on the temporal trends in abundance of vertebrate populations. The Med LPI was based on 1641 vertebrate populations of 311 species recorded in Mediterranean wetlands from 1970–2008, in 27 different countries. We investigated whether trends in the Med LPI differed between eastern and western Mediterranean countries, which have different socio-economic contexts. Finally, we assessed whether and how the trend in the Med LPI was robust to changes in the number and identity of species considered. We found that, at the Mediterranean scale, the Med LPI increased steeply, which could be taken at first sight, as a general recovery of wetland biodiversity in this biogeographical region. However, we found highly contrasting spatial trends within the Mediterranean region: the average trend was positive for western and negative for eastern countries. Moreover, we showed that depending on the method used to estimate the trend in Med LPI, it can be sensitive to the number and identity of the species considered. We suggest that understanding the regional discrepancies of the trend in biodiversity indicators as well as their robustness to the species represented in the index will enhance progress assessment towards global and regional conservation strategies.     

中国高等级旅游资源数量与旅游人数、旅游收入的关系研究

旅游资源是旅游业发展的基础,其数量与质量直接影响区域旅游业发展的水平与规模.但在旅游资源质量基本一致的情况下,其数量对旅游发展的影响如何的研究较少,故文中选取全国及31个省区(不包括香港、澳门与台湾)17种世界级、国家级旅游资源数量、旅游人数、旅游收入的数据,对旅游资源数量与旅游人数、旅游收入的关系进行了实证分析.结果...     

Fungal abundance and distribution as influenced by clearing and land use in a vertic soil of Argentina

The influence of native vegetation clearing and different further soil managements on fungal propagule population diversity was studied in the present work. In each of the 3 years (1998, 1999, and 2000), soil samples were collected at the depth of 0–7.5 cm from sites under native vegetation (V0); naturalized prairie, cleared in 1982 (P16); conventional tillage, cleared in 1972 (T26); and direct drilling, cleared in 1958 (D40). Fungal population size and relative abundance of fungal genera were studied by plate counts and further identification of isolates on potato dextrose agar. The undisturbed site and the other sites with increasing time elapsed since native vegetation clearing and different management history showed a distinctive distribution of fungal genera. There were significant differences (p<0.05) among the sites in the abundance of fungal genera analyzed in all the 3 years. Principal component analysis based on relative fungal genus abundance differentiated the sites with 75% variance explained by the first and second components. Diversity and abundance of isolated fungal genera were increased as density of Penicillium spp. decreased, suggesting a competitive effect of this fungal genus. The largest diversity was found in the site under no-till management. The different distribution and relative abundance of the fungal genera studied seemed to be influenced strongly by the management and the presence of surface residue in the no-tilled site.     

Isotopic fractionation during N2 fixation by four tropical legumes

To quantify the contribution of biological nitrogen fixation (BNF) to legume crops using the ¹⁵N natural abundance technique, it is necessary to determine the ¹⁵N abundance of the N derived from BNF—the B value. In this study, we used a technique to determine B whereby both legume and non-N₂-fixing reference plants were grown under the same conditions in two similar soils, one artificially labelled with ¹⁵N, and the other not. The proportion of N derived from BNF (%Ndfa) was determined from the plants grown in the ¹⁵N-labelled soil and it was assumed that the %Ndfa values of the legumes grown in the two soils were the same, hence the B value of the legumes could be calculated. The legumes used were velvet bean (Mucuna pruriens), sunnhemp (Crotalaria juncea), groundnut (Arachis hypogaea) and soybean (Glycine max) inoculated, or not, with different strains of rhizobium. The values of %Ndfa were all over 89%, and all the legumes grown in unlabelled soil showed negative δ¹⁵N values even though the plant-available N in this soil was found to be approximately +6.0‰. The B values for the shoot tissue (B_s) were calculated and ranged from approximately −1.4‰ for inoculated sunnhemp and groundnut to −2.4 and −4.5‰ for soybean inoculated with Bradyrhizobium japonicum strain CPAC 7 and Bradyrhizobium elkanii strain 29W, respectively. The B (B_wp) values for the whole plants including roots, nodules and the original seed N were still significantly different between the soybean plants inoculated with CPAC 7 (−1.33‰) and 29W (−2.25‰). In a parallel experiment conducted in monoxenic culture using the same soybean variety and Bradyrhizobium strains, the plants accumulated less N from BNF and the values were less negative, but still significantly different for soybean inoculated with the two different Bradyrhizobium strains. The results suggest that the technique utilized in this study to determine B with legume plants grown in soil in the open air, yields B values that are more appropriate for use under field conditions.     

中亚热带丝栗栲群落物种-个体关系的研究

对中亚热带丝栗栲群落物种 个体关系研究结果表明 ,剩余标准差 (RSE)、偏差绝对值平均值 (AAD)和相对偏差绝对值平均值 (AARD) 3个评价指标之间存在极强正秩相关 ,表明它们对物种 个体关系模型评价结果具很强一致性 ,乔木层 5种曲线拟合效果最佳为y =1.85 18x2 - 7.84 86x 14 .5 ,灌木层 5种曲线拟合效果最佳为y =12 4 84e0 .1572x;群落中乔木层和灌木层物种多度分布均遵从对数正态分布 ,表明该丝栗栲群落发展较成熟 ,稳定性和生物多样性较高     

重庆市土壤有机碳库的估算及其空间分布特征

基于重庆市第二次土壤普查的1411个土壤剖面数据，结合重庆市土壤图、土地利用现状图和行政区划图，在地理信息系统技术的支持下，对重庆市土壤有机碳密度及储量进行了估算、同时引入有机碳丰度指数这一指标，对有机碳在不同土壤、不同区域以及不同景观中的分布特征进行了分析。结果表明：重庆市20cm和100cm深度的土壤有机碳储量分别为0．27Tg和1．0Tg；20cm深度的土壤有机碳密度介于0．33～30．36kg／m^2之间．100cm深度的土壤有机碳密度介于1．27～72．69kg／m^2之间；重庆市土壤有机碳库在不同土壤、不同区域以及不同景观的分布具有高度的空间变异性，100cm深度的土壤、区域和景观有机碳丰度指数分别为0．58～1．95，0．55～1．39和0．46～1．58．与气候、植被、人类活动等因素密切相关。     

Bacteria and fungi on roots of different barley varieties (Hordeum vulgare L.)

Summary We investigated the abundance of bacteria and fungi on roots of different barley varieties grown in soil and in a nutrient solution. Measurements were made on the rhizoplane and, for soil-grown plants, also in the rhizosphere soil. Further, the influence of plant age was investigated. Barley variety, had a significant influence both for plants grown in soil and in the nutrient solution, and the effects were most pronounced on the rhizoplane. There were no significant differences among varieties in fungal hyphal lengths on the roots. Bacterial abundance on the rhizoplane was significantly decreased with increasing plant age. Varietal differences were maintained over different plant ages.     

种子贮藏蛋白质丰度研究进展

种子贮藏蛋白质丰度研究是种子蛋白质组学研究的重要领域,对于明确蛋白质丰度与种子进化、结构和萌发的分子机制等具有重要意义,同时可应用于种质的分子改良,并能将种子作为转基因产物生产的优良平台。对不同类型种子发育和萌发过程中的贮藏蛋白质丰度研究进展进行了概述,同时介绍了蛋白质丰度研究中贮藏蛋白质的样品制备方法。     

Fish assemblages as influenced by environmental factors in streams in protected areas of the Czech Republic

Abstract –  Three streams of comparable size located in different landscape-protected areas were selected for studying the effect of environmental factors on fish assemblages using indirect (detrended correspondence analysis, DCA) and direct (canonical correspondence analysis, CCA) gradient analysis. DCA of species showed well a gradient of assemblage changes in the longitudinal profile. DCA of sites stressed the variability between the fish assemblages of the three streams. This pattern was then confirmed by the highly significant between-stream CCA. In the within-site CCA, environmental factors explained 50.7% variability for presence–absence data and 58.3% for the relative abundance data. The analysis revealed that number of ponds and land use are the most influential factors of the strongest environmental gradient. However, in the partial CCAs, factor substratum type explained the largest proportion of the variability affecting fish in their habitat choice. Generally, presence–absence and relative abundance data of fish gave similar results in both DCA and CCA analyses; the same environmental factors proved to be important in both data type analyses. The environmental factors explain more variability than the regional (between-stream) one. The total proportion of variability explained by the presence–absence data analysis was 71.9% and in the relative abundance analysis even 80.8%. The environmental factors measured during the field survey explain 2.1- and 3.4-times more assemblages' variability than factors measured from a hydrological map.     

Discrimination and abundance estimation of wild and released abalone Haliotis diversicolor using stable carbon and oxygen isotope analysis in north-eastern Taiwan

The discrimination between wild and released Taiwan abalone Haliotis diversicolor was performed by stable carbon isotope analysis. Abalone samples were collected from Mao Aw Gulf in north-eastern Taiwan. Live abalone and dead shells were collected by divers with an 80 × 80 cm frame. The densities and amounts of wild and released abalone, as well as the survival rates of released abalone, in 1997 and 1998 were estimated. The age of the specimens was also determined from the specific temperature of each month and the inverse relationship between oxygen isotope values and temperatures. Results show that examining stable isotopic profiles proves to be a practical and feasible method for stock discrimination as well as density and abundance estimation. These data would be helpful in assessing the success of abalone culture and release programs, which aim to enhance this valuable marine resource.