Soil Diversity as Affected by Land Use in China: Consequences for Soil Protection

Rapid land-use change in recent decades in China and its impact on terrestrial biodiversity have been widely studied, particularly at local and regional scales. However, the effect of land-use change on the diversity of soils that support the terrestrial biological system has rarely been studied. Here, we report the first effort to assess the impact of land-use change on soil diversity for the entire nation of China. Soil diversity and land-use effects were analyzed spatially in grids and provinces. The land-use effects on different soils were uneven. Anthropogenic soils occupied approximately 12% of the total soil area, which had already replaced the original natural soils. About 7.5% of the natural soil classes in China were in danger of substantial loss, due to the disturbance of agriculture and construction. More than 80% of the endangered soils were unprotected due to the overlook of soil diversity. The protection of soil diversity should be integrated into future conservation activities

Salinity appears to be the main factor shaping spatial COI diversity of Corbicula lineages within the Chinese Yangtze River Basin

info:eu-repo/semantics/publishe

Nutrient enrichment homogenizes taxonomic and functional diversity of benthic macroinvertebrate assemblages in shallow lakes

Eutrophication alters the trophic dynamics in lakes and may result in biotic homogenization. How nutrient enrichment drives patterns of taxonomic and functional (i.e., trait‐based) homogenization of macroinvertebrate assemblages at within‐lake (local) and among‐lake (regional) scales is, however, not well understood. Taxonomic and functional compositions of macroinvertebrate assemblages in 41 lakes of the middle and lower reaches of the Yangtze River and Huaihe River were analyzed at within‐lake and among‐lake scales. Our results indicated that there was a significant difference in macroinvertebrate assemblages among lakes under different trophic status, and that total phosphorus was the major environmental factor that regulated both taxonomic and functional beta diversity of macroinvertebrate assemblages. That the abundances of pollution‐tolerant species (e.g., Limnodrilus hoffmeisteri and Microchironomus tabarui) increased with trophic state contributed the most to among‐lake dissimilarity. Functional beta diversity was significantly positively correlated with taxonomic beta diversity, while functional beta diversity was on average lower than taxonomic beta diversity. A combination of univariate and multivariate techniques revealed that nutrient enrichment homogenized taxonomic and functional diversity of benthic macroinvertebrate assemblages in shallow lakes at within‐lake and among‐lake scales, and that there was an overall trend toward taxonomic homogenization that exceeded the trend of functional homogenization. Thus, taxonomic and functional compositions should be considered simultaneously to improve understanding of the response of aquatic communities to anthropogenic disturbance, as the loss and gain of species may be influenced by species‐specific features, and functional composition may exhibit a relatively high correspondence with changes in environmental conditions

Metacommunity ecology meets bioassessment : Assessing spatio-temporal variation in multiple facets of macroinvertebrate diversity in human-influenced large lakes

Highlights • We examined drivers of 6 biotic metrics in a metacommunity context in two large lakes. • The relative roles of spatial, human-induced and natural factors were quantified. • The roles of spatial variables are comparable with local environmental conditions. • The relative roles of different drivers varied substantially among seasons. • Spatial processes, natural conditions and temporal variation should be considered.Metacommunity theory emphasizes that local communities are jointly affected by environmental filtering and spatial processes. However, the roles of spatial processes are often given insufficient attention in bioassessment practices, which may bias the assessments of ecological status based on biotic metrics. Here, we quantified the relative importance and the seasonal stability of spatial processes, natural conditions and human-induced factors in structuring variation in different bioassessment metrics based on macroinvertebrate communities. Our study systems were two extensively sampled large and shallow lakes with strong nutrient gradients related to human disturbance. The roles of different drivers were examined for three kinds of indicators: general diversity, trait-based and taxonomic distinctness metrics, and their performance in characterizing human disturbance was evaluated. Overall, human-induced and spatial factors were all important in explaining variation in the three types of bioassessment metrics. Contrary to our expectations, however, we found that the importance of spatial processes on bioassessment metrics can be comparable to the effects of local environmental conditions at the within-lake scale. Furthermore, the results showed substantial seasonal variability in the relative roles of different drivers, which might be linked to life-cycle seasonality of macroinvertebrates. As expected, trait-based metrics generally were best associated with human-induced variables in both lakes, whereas general diversity and taxonomic distinctness metrics performed poorly. The low effectiveness of taxonomic distinctness metrics might due to low species richness associated with high nutrient levels. To conclude, our results suggest that bioassessment cannot exclusively rely on the idea of environmental filtering even if we focus on fine spatial scales. We hence strongly urge that spatial processes, natural drivers and temporal variability should be better considered in combination in the development and application of bioassessment approaches. In addition, taxonomic distinctness measures should be used with caution, especially for the ecosystems and organism groups typically characterized by low species richness

Effects of Land Use Characteristics, Physiochemical Variables, and River Connectivity on Fish Assemblages in a Lowland Basin

Human disturbances can have severe environmental impacts on freshwater ecosystems. The main aim of this study is to detect the influences of physiochemical variables, land-cover characteristics, and river connectivity on fish assemblages in the Lake Chaohu Basin, China. A cluster analysis of river connectivity variables identified four groups of sites characterized by significantly different connectivity gradients at a local scale. These four groups of sites showed increasing connectivity from the upper reaches to the lower reaches. At the same time, among the four groups, the values of environmental variables generally increased from the upper reaches with less human activities towards the lower reaches with more human activities. For instance, some main physiochemical variables (e.g., river width, water depth, nitrate, phosphate) significantly increased among the four groups. In contrast, fish taxa richness and diversity indices were not significantly different among the four connectivity groups. However, fish assemblages showed significant variations among the connectivity groups (p = 0.026). In addition, the study determined that upper riparian land uses (e.g., woodland and grassland), flow velocity, and elevation were environmental variables regulating the variance of fish communities. As for the connectivity variables, only river order and the number of branches along a path to the left of the main stem affected the variance of fish communities. Therefore, new practices aimed at maintaining and even increasing riparian canopy coverage and the flow velocity of rivers should be integrated into local conservation planning for freshwater ecosystems, especially in the upper reaches of the basin

Design on the Control System of a Gait Rehabilitation Training Robot Based on Brain-Computer Interface and Virtual Reality Technology

In this paper a control system of a gait rehabilitation training robot based on Brain-Computer Interface (BCI) and virtual reality technology is proposed, which makes the patients' rehabilitation training process more interesting. A technique for measuring the mental states of the human and associated applications based on normal brain signals are examined and evaluated firstly. Secondly, the virtual game starts with the information from the BCI and then it runs in the form of a thread, with the singleton design pattern as the main mode. Thirdly, through the synergistic cooperation with the main software, the virtual game can achieve quick and effective access to blood oxygen, heart rate and other physiological information of the patients. At the same time, by means of the hardware control system, the start-up of the gait rehabilitation training robot could be controlled accurately and effectively. Therefore, the plantar pressure information and the velocity information, together with the physiological information of the patients, would be properly reflected in the game lastly and the physical condition of the patients participating in rehabilitation training would also be reflected to a great extent

Geographical gradients in the biodiversity of Chinese freshwater molluscs: Implications for conservation

Aim: Large-scale diversity patterns are generated by different but not mutually exclusive mechanisms. However, understanding of multiple facets of diversity and their determinants in the freshwater realm remains limited. Here, we characterized the geographical gradients, hotspots and spatial congruence of three facets of freshwater molluscan diversity and evaluated the relative importance of three different underlying mechanisms related to the energy, area/environmental heterogeneity and dispersal/historical hypotheses. Location: China. Methods: Species richness (SR), functional richness (FR) and taxonomic distinctness (TD, a proxy of phylogenetic diversity) were calculated for 212 drainage basins with a total of 313 molluscan species. Spatial congruence between the diversity facets was evaluated with Pearson correlation coefficient and overlap among hotspots. Multiple linear regression models and variation partitioning were used to assess the relative importance of different mechanisms. Results: Hotspots of SR and FR were mainly concentrated in the Yangtze River and Huai River basins, while high TD values were patchily distributed across China. We found extremely low spatial congruence between TD and both SR and FR, while there was relatively high concordance between SR and FR. All diversity facets were best explained by the dispersal/historical hypothesis with strong unique effects, followed by the factors related to the energy hypothesis. The area/environmental heterogeneity hypothesis was only weakly supported. Main conclusions: We found a potentially strong influence of dispersal limitation and evolutionary history on the geographical diversity gradients of Chinese molluscs. This finding contrasts with the general finding that energy-related factors are the strongest correlates of diversity patterns at large spatial scales. Moreover, our results do not support the idea that using any one diversity component as a surrogate of the others in developing conservation strategies. Instead, an integrative approach embracing multiple facets of diversity should be adopted in the conservation of freshwater biodiversity

Optimal response to habitat linkage of local fish diversity and mean trophic level

Spatially segregated ecosystems are frequently subsidized by cross-habitat linkages, but the extent to which the functional links between habitats influence local community attributes, such as consumer and food web structure is still poorly understood. Using the bidirectional linkage between benthic and pelagic habitats in floodplain lakes, we address this important question by looking for evidence of an optimal extent of habitat linkage supporting maximum taxonomic richness and mean trophic level. We then ask if there are significant changes in these local community attributes between historical and current communities, and if these reflect the history of species loss resulting from the intense human alteration of these lakes. We found a strong optimal response of maximum richness and mean trophic level along the pelagic-benthic gradient, both across and within individual lakes. This is consistent with the expectation of optimal resource availability along the habitat linkage gradient supporting more and taxonomically richer communities. Comparison between historical and current assemblages revealed a significant decrease in the optimal linkage for maximum richness in response to the history of species loss, but not for maximum mean trophic level, probably a response to the increased habitat homogenization and enhanced productivity caused by the recent history of nutrient-enrichment and habitat alteration. Our study provides strong evidence of high diversity and trophic level occurring at intermediate levels of coupling between pelagic and benthic resources, suggesting assemblage reliance on multiple production sources, and offers novel insight into the responses of this relationship to species loss due to human activities