Grasshopper plagues have seriously disturbed grassland ecosystems in Inner Mongolia, China. The accurate prediction of grasshopper infestations and control of grasshopper plagues have become urgent needs. We sampled 234, 342, 335, and 369 plots in Xianghuangqi County of Xilingol League in 2010, 2011, 2012, and 2013, respectively, and measured the density of the most dominant grasshopper species, Oedaleus decorus asiaticus, and the latitude, longitude, and associated relatively stable habitat factors at each plot. We used Excel-GeogDetector software to explore the effects of individual habitat factors and the two-factor interactions on grasshopper density. We estimated the membership of each grasshopper density rank and determined the weights of each habitat category. These results were used to construct a model system evaluating grasshopper habitat suitability. The results showed that our evaluation system was reliable and the fuzzy evaluation scores of grasshopper habitat suitability were good indicators of potential occurrence of grasshoppers. The effects of the two-factor interactions on grasshopper density were greater than the effects of any individual factors. O. d. asiaticus was most likely to be found at elevations of 1300-1400 m, flat terrain or slopes of 4-6°, typical chestnut soil with 70-80% sand content in the top 5 cm of soil, and medium-coverage grassland. The species preferred temperate bunchgrass steppe dominated by Stipa krylovii and Cleistogenes squarrosa. These findings may be used to improve models to predict grasshopper occurrence and to develop management guidelines to control grasshopper plagues by changing habitats.
-Incompletely known fish assemblages and species diversity are substantial obstacles in fish conservation, particularly when their aquatic habitats are under threat due to rapid human-induced changes. Fish assemblages and diversity in three tributaries of the upper Irrawaddy River in China (the Dulong, Daying and Ruili rivers) were examined based on field collections and literature resources. The newly compiled fish assemblage recorded 85 species (in 8 orders, 20 families and 51 genera) distributed in the upper Irrawaddy. The fish compositions in the Daying (67 species, 44 genera, 19 families, 7 orders) and Ruili rivers (65 species, 44 genera, 19 families, 8 orders) were more similar to each other and more speciose than that in the Dulong River (14 species, 10 genera, 4 families, 3 orders). Two indices of taxonomic diversity (the average taxonomic distinctness (Δ + ), and the variation in taxonomic distinctness (Λ + )) were used to discriminate four collections spanning a ten-year period. A decrease in taxonomic diversity and an increase in unevenness of the fish assemblages were found in both the Daying River and Ruili rivers, which indicated that the impacts were accumulated gradually during this decade, when dams and the spread of non-native species were major threats. Comparatively speaking, the Dulong River is still in a near-natural state, and thus the fish community has experienced less disturbance. In situ conservation (nature reserves and tributary protection) and ex situ conservation (artificial propagation and release) should be combined and managed to promote fish conservation in the future. Key-words:Freshwater fish / taxonomic diversity / threats / dams / Irrawaddy Résumé -La diversité et les communautés de poissons dans trois affluents de la rivière Irrawaddy en Chine : changements, menaces et perspectives de conservation. Les assemblages de poissons et leur diversité spécifique incomplètement connus sont d'importants obstacles à la conservation des poissons, en particulier lorsque leurs habitats aquatiques sont menacés en raison des rapides changements induits par l'homme. Les assemblages de poissons et leur diversité dans trois affluents de la rivière Irrawaddy supérieure en Chine (les rivières Dulong, Daying et Ruili) ont été étudiés sur la base de collectes sur le terrain et des ressources de la littérature. L'assemblage de poissons nouvellement compilé comporte 85 espèces (8 ordres, 20 familles et 51 genres) répartis dans l'Irrawaddy supérieure. Les compositions de poissons dans les rivières Daying (67 espèces, 44 genres, 19 familles, 7 ordres) et Ruili (65 espèces, 44 genres, 19 familles, 8 ordres) sont plus semblables les uns aux autres et plus riches en espèces que dans la rivière Dulong (14 espèces, 10 genres, 4 familles, 3 ordres). Deux indices de diversité taxonomique (la taxonomique moyenne (Δ + ), et la variation de la distance taxonomique (Λ + )) ont été utilisés pour discriminer quatre échantillonnages couvrant une période de dix ans. Une diminution de la diversité taxonomi...
The biogeographic distribution of plants and animals on the Qinghai–Tibetan Plateau (QTP) has been extensively studied; however, the biogeographic patterns and factors affecting bacterial communities in alpine grassland ecosystems over large scales were not fully understood. In this paper, we explored the biogeographic patterns of soil bacterial communities in wet meadow, meadow, and steppe. The results showed that bacterial α‐diversity was similar in the three grassland types, while bacterial β‐diversity differed significantly. The dominant bacteria were Proteobacteria (29.86%), Acidobacteriota (17.76%), and Actinobacteriota (16.42%), which were caused by the changes in soil pH, C/N, and soil moisture. In addition, the significant distance–decay of bacterial communities was found across environmental and geographical distances. Partial Mantel test showed that the differences of bacterial community in wet meadow and meadow were influenced by environmental and geographical factors, while the difference of bacterial community in steppe was only affected by geographical distance. The MRM accounted for 38.7%, 37.2%, and 11.8% of the variability in wet meadow, meadow, and steppe, respectively. In wet meadow and meadow, geographic distance was the most powerful factor in explaining the similarity of bacterial communities, while soil moisture was the most critical factor in steppe. It was obvious that environmental and geographical factors played different roles in shaping structures of bacterial community in wet meadow, meadow, and steppe, which provided new insights for the effective management of alpine grassland.
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