Collaborative research: Controls over decomposition by microbial communities under climate change

点击翻译按钮获取中文摘要

One way that microbes, including bacteria and fungi, play a critical role in the global carbon cycle is by recycling dead plant matter into nutrients and carbon dioxide. Although necessary for plant growth, carbon dioxide is also a greenhouse gas, so changes in activities of the Earth's tiniest life forms could have affects on a global scale. Warming temperatures, in turn, could affect microbial activities. If warming increases microbial activities and carbon dioxide production, there could be a positive feedback that compounds the severity of environmental changes. The goal of this project is to study the effects of temperature warming on natural communities of microorganisms in soil. The research team will use cutting-edge experimental and computational tools to analyze the importance of microbial diversity. The project investigators have designed an experiment to test how well microbes from one climate do in another. For example, they will transplant microbes from a cool, wet mountaintop and measure how fast they can recycle dead plant matter in a desert. It's plausable that the mountaintop microbes will lack essential genes for survival in a desert - genes that desert microbes already have. To test this possibility, the investigators will use DNA sequencing to identify the genes present in nearly all of the microbes from each climate condition. The study will also test whether all microbes are equivalent and speed up their metabolism when the temperature rises. The investigators will apply a sophisticated computer model to extend their experimental findings. The broad societal impacts of this project include training for a postdoctoral researcher and four graduate students, new computational infrastructure, and an outreach-education program for visitors to a California state park. Student and postdoctoral training will focus on interdisciplinary research that links microbial diversity with environmental change. The investigators will make their computer models available on the Web so that they are easily accessible to the scientific community. This project will train a postdoctoral scientist and four graduate students, develop computational infrastructure, and establish an outreach-education program for visitors to a California state park. Training will focus on interdisciplinary research that links microbial ecology and genomics with ecosystem function. A specific aim of this project is to develop a web-based version of the microbial community model for dissemination to the scientific community. On the local scale, the PIs will partner with a University of California-Irvine outreach internship program and the non-profit Crystal Cove Alliance to develop an interactive research education station for visitors to Crystal Cove State Park, CA. Park visitors will have the opportunity to learn about the ecosystem process of litter decomposition and the consequences of microbial diversity in the context of climate change.Conventional ecosystem models assume that biogeochemical rates are independent of microbial community composition, yet emerging empirical evidence contradicts this assumption. In light of this new evidence, the investigators hypothesize that litter decomposition rates and responses to climate change depend on microbial community composition. They will test this hypothesis by manipulating microbial community composition and transplanting communities across a climate gradient in southern California. The hypothesis would be supported if different communities transplanted into the same location decompose litter at different rates. Similarly, the response of litter decomposition rate to climate variation across the gradient should vary for different microbial communities. This project will also analyze the microbial traits underlying differences (or similarities) in microbial community function. The investigators hypothesize that variation in decomposition rates across different microbial communities will be driven by extracellular enzyme traits. Likewise, variation in the microbial community response to climate change should relate to differences in 'response traits' such as drought and temperature tolerance. These hypotheses will be tested by sequencing the metagenomes of litter microbial communities and extracting functional traits using bioinformatics analyses. The taxonomic composition of the microbial communities will be quantified with high-throughput sequencing of 16S and ITS markers for bacteria and fungi. Finally, the investigators aim to examine the consequences of their experimental results under future climate change predictions. Molecular and ecosystem data will be incorporated into a simulation model that accounts for microbial community composition. The transplant manipulation results will be compared to model simulations with and without diverse microbial communities to test the importance of composition for function. Following a model selection procedure, the investigators will simulate litter decomposition under climate change scenarios in southern California. These efforts will reveal the consequences of microbial community composition for ecosystem responses to future climate change.