The Xia lab uses tools of field experiments, remote-sensing data products, national survey data, and process-based models to explore the responses and adaptation of terrestrial ecosystems (e.g., forests, grassland, and wetland) to climate change, especially the extreme climate events.
Our researches are driven by three primary questions:
(1) How the carbon sink capacity of terrestrial ecosystems changes with the shifting climate regime?
(2) How to improve the predict ability of climate-carbon cycle feedback in current Earth system models?
(3) How does nitrogen cycle interacted with carbon cycle in terrestrial ecosystem?
Our researches are driven by three primary questions:
(1) How the carbon sink capacity of terrestrial ecosystems changes with the shifting climate regime?
(2) How to improve the predict ability of climate-carbon cycle feedback in current Earth system models?
(3) How does nitrogen cycle interacted with carbon cycle in terrestrial ecosystem?
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The model projection of future climate change is highly uncertain. This largely stems from the large uncertainty of feedbacks between the carbon cycle and climate change in the Earth system models (ESMs). Reducing this uncertainty requires better diagnostic framework and benchmarking system. We are developing the “traceability framework” which aims to trace the uncertainty of simulated terrestrial biogeochemistry in ESMs to their sources in model structures and parameters. We are trying to incorporate the field experiments into the traceability framework.
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In terrestrial ecosystems, cycles of carbon and nitrogen are tightly linked. Thus, it is unrealistic that many current global models ignore the coupling between these two cycles. In those models alrealy incorporated C-N coupling, there are diverse hypotheses for the underline mechanisms. We are doing many data-driven analyses on the impacts of adding nitrogen on carbon processes. We are also developing models to better represent the coupling between carbon and nitrogen models. The different C-N coupling hypotheses are examined by case studies with process-based models and in-situ observations. We also design new experiments to improve our understanding in this area.
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Transitions (e.g., costal wetland and rangeland) are more sensitive to the rapid climate change than other regions. It is unclear whether and how the shifting climate regime would affect the ecosystem functions in those transitions areas. We are conducting field experiments and regional survey to explore the the mechanisms and general patterns. We have alrealy set up a long-term field experiment at the Yellow River Delta, which aims to study the response of a costal wetland to the increasing stresses of summer/autumn drought and winter/spring warming.
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