Ecosystems worldwide are undergoing rapid change due to human activities. In order to protect and sustain altered ecosystems, better understanding of the nature of the changes and how fast they are happening is needed. This type of research inherently crosses traditional science discipline boundaries; knowledge of chemistry or ecology or physics alone will not enable adequate understanding. Students and faculty receiving disciplinary training also need to learn how to communicate across disciplines as part of scientific teams. The significance of this CAREER project is that it will address both an important scientific issue, as well as helping foster new interdisciplinary research in global change ecology. The primary research goal of the project is to understand when, or whether, carbon sequestered in soils will act as a positive feedback to increasing carbon dioxide (CO2) in the atmosphere, thus reinforcing climate warming. Specifically, the research team will quantify the response of soil decomposer micro-organisms to climate change and measure CO2 output from the soil. The education goal of the project is to support interdisciplinary training for ecologists interested in global change issues.
The broader societal significance of the project will be the impacts on interdisciplinary graduate student training and faculty development, as well as its potential importance for predicting ecosystem response to climate warming. Current predictions of changes in atmospheric CO2 do not include detailed treatment of the decomposer community. However, the response of the microbial community to warming could act as an important control over release of greenhouse gases to the atmosphere. This integrated research and education project will substantially increase our understanding of that control.
The majority of the work supported by this award was conducted in Prof. Teri Balser’s lab at UW-Madison before transferral in fall 2011 to the Marin-Spiotta lab, who oversaw the project's completion. The role of soils as a net carbon source or sink in response to changes in climate is currently a matter of intense interest in global change policy and research. Because soils store more than twice the amount of carbon in the atmosphere, even small changes in the quantity of carbon added and released from soils can have a significant impact on atmospheric carbon dioxide, an important greenhouse gas, which contributes to increased global mean temperatures. The overarching goals of the project were (1) to increase our understanding of and ability to predict soil carbon responses to global ecological changes by investigating the role of microbes in driving changes in soil carbon, and (2) to improve interdisciplinary environmental graduate and undergraduate education. To better understand the responses, processes and factors relating to carbon sequestration and loss from soils, our approach included field and laboratory studies as well as broad synthesis and modeling activities. This work has resulted in 23 scientific and 2 educational publications, over 20 scientific presentations at national and international conferences, and almost 20 educational and public outreach presentations. New collaborations across multiple labs and institutions were established through this work, and funding supported the training of graduate students, undergraduate students, and a postdoctoral researcher. To address environmental and interdisciplinary education we organized and delivered a workshop, created and offered a graduate course focused on active learning in large classrooms, and developed an undergraduate environmental literacy course. Research activities focused on understanding the long-term response of soil microbes and soil carbon to changes in climate and other environmental factors, such as vegetation type and land use. We studied microbial community composition and activity in soils from a variety of geographic locations under different temperature and precipitation as well as plant cover types to test if the temperature sensitivity of soil carbon is uniform across environments. Many models often assume that the identity of the microbes is not important for predicting the response of certain soil processes, but our results indicated different responses to changing climatic conditions by different microbes. Our work in temperate and tropical forests and grasslands revealed that plant type can influence the amount and composition of microbes in soils, which affects carbon sequestration, soil fertility and plant growth. We developed a method for using amino sugars as a chemical signature to track changes in the contribution of bacteria and fungi to soil carbon, which differentially affect how long carbon persists in soils. We created a framework for predicting the response of soil C under warming experimental manipulations and corresponding changes in microbial communities. We found that persistent soil carbon is particularly vulnerable to being released from warmed soils, and that this vulnerability can depend on the process responsible for long-term carbon retention in the soil. We found strong geographic differences in the types of microbes in soils and in their response to warming, with stronger responses seen for arctic/subarctic soils compared to temperate or tropical soils. We produced a model that relates soil microbial community make-up with the types of carbon consumed, as well as a model quantifying how soil microbial biomass is incorporated into the soil carbon pool. In summary, this work has contributed to improving our understanding about the interactions between environmental change, soil microbes and carbon cycling in soils, which can improve modeling efforts to predict feedbacks between rising air temperatures and atmospheric carbon dioxide concentrations. The educational activities supported through this grant contributed to new approaches to teaching environmental science at the undergraduate and graduate level.
