【河流中的反硝化作用】Corianne Tatariw 1 Elise L. Chapman 1 Ryan A. Sponseller 2 Behzad Mortazavi 13 and Jennifer W. Edmonds 14. Denitrification in a large river: consideration of geomorphic controls on microbial activity and community structure. Ecology 94:2249–2262.
Abstract
Ecological theory argues that the controls over ecosystem processes are structured hierarchically with broader-scale drivers acting as constraints over the interactions and dynamics at nested levels of organization. In river ecosystems these interactions may arise from broadscale variation in channel form that directly shapes benthic habitat structure and indirectly constrains resource supply and biological activity within individual reaches. To evaluate these interactions we identified sediment characteristics water chemistry and denitrifier community structure as factors influencing benthic denitrification rates in a sixth-order river that flows through two physiographic provinces and the transitional zone between them each with distinct geomorphological properties. We found that denitrification rates tracked spatial changes in sediment characteristics and varied seasonally with expected trends in stream primary production. Highest rates were observed during the spring and summer seasons in the physiographic province dominated by fine-grained sediments illustrating how large-scale changes in river structure can constrain the location of denitrification hotspots. In addition nirS and nirK community structure each responded differently to variation in channel form possibly due to changes in dissolved oxygen and organic matter supply. This shift in denitrifier community structure coincident with higher rates of N removal via denitrification suggests that microbial community structure may influence biogeochemical processes.
【降水对土壤微生物群落功能和组成的影响】L. H. Zeglin P. J. Bottomley A. Jumpponen C. W. Rice M. Arango A. Lindsley A. McGowan P. Mfombep and D. D. Myrold 2013. Altered precipitation regime affects the function and composition of soil microbial communities on multiple time scales. Ecology 94:2334–2345.
Abstract
Climate change models predict that future precipitation patterns will entail lower-frequency but larger rainfall events increasing the duration of dry soil conditions. Resulting shifts in microbial C cycling activity could affect soil C storage. Further microbial response to rainfall events may be constrained by the physiological or nutrient limitation stress of extended drought periods; thus seasonal or multiannual precipitation regimes may influence microbial activity following soil wet-up. We qu
