【半干旱草原土壤微生物群落】Ming Nie Elise Pendall Colin Bell Caley K. Gasch Swastika Raut Shanker Tamang Matthew D. Wallenstein. Positive climate feedbacks of soil microbial communities in a semi-arid grassland. Ecology Letters 201316(2): 234–241

Abstract

Soil microbial communities may be able to rapidly respond to changing environments in ways that change community structure and functioning which could affect climate–carbon feedbacks. However detecting microbial feedbacks to elevated CO₂ (eCO₂) or warming is hampered by concurrent changes in substrate availability and plant responses. Whether microbial communities can persistently feed back to climate change is still unknown. We overcame this problem by collecting microbial inocula at subfreezing conditions under eCO₂ and warming treatments in a semi-arid grassland field experiment. The inoculant was incubated in a sterilised soil medium at constant conditions for 30 days. Microbes from eCO₂ exhibited an increased ability to decompose soil organic matter (SOM) compared with those from ambient CO₂ plots and microbes from warmed plots exhibited increased thermal sensitivity for respiration. Microbes from the combined eCO₂ and warming plots had consistently enhanced microbial decomposition activity and thermal sensitivity. These persistent positive feedbacks of soil microbial communities to eCO₂ and warming may therefore stimulate soil C loss.

【微生物菌组成和多样性预测植物生产力及植-土反馈】James D. Bever Linda M. Broadhurst Peter H. Thrall. Microbial phylotype composition and diversity predicts plant productivity and plant–soil feedbacks. Ecology Letters 201316(2): 167–174

Abstract

The relationship between ecological variation and microbial genetic composition is critical to understanding microbial influence on community and ecosystem function. In glasshouse trials using nine native legume species and 40 rhizobial strains we find that bacterial rRNA phylotype accounts for 68% of amoung isolate variability in symbiotic effectiveness and 79% of host specificity in growth response. We also find that rhizobial phylotype diversity and composition of soils collected from a geographical breadth of sites explains the growth responses of two acacia species. Positive soil microbial feedback between the two acacia hosts was largely driven by changes in diversity of rhizobia. Greater rhizobial diversity accumulated in association with the less responsive host species Acacia salicina and negatively affected the growth of the more responsive Acacia stenophylla. Together this work demonstrates correspondence of phylotype with microbial function and demonstrates that the dynamics of rhizobia on host species can feed back on plant population performance.

【不同气候带森林多样性】Jonathan A. Myers Jonathan M. Chase Iván Jim&eacut