The Dynamic Land Ecosystem Model (DLEM): Coupling of biophysical, biogeochemical, hydrological, vegetation dynamical and land use processes for multi-scale ecological forecasting

Background/Question/Methods

Each process in ecosystem is connected to other processes, which makes a unified whole.  Ecosystem model has been considered as an essential tool for understanding and predicting how ecosystems as a whole respond to multifactor global changes at multiple scales from site to global. The purpose of models, however, is to simplify the complexity of whole system so that we have to decouple the interrelated processes.  To make model more mechanistic and predictive, on the other hand, ecosystem modeling needs to couple various processes that are responsible for the spatial and temporal patterns of ecosystems across the land surface. Due to accumulating data and increasing understanding on how ecosystem works, it is possible to make our models more mechanistic. Although a number of process-based models exist, it is still a big challenge to couple multiple processes and patterns in an ecosystem model for ecological forecasting.

Results/Conclusions

Based on our improved knowledge of the fundamental mechanisms, from molecular systems to the planetary ecosystem, and supported by the rapidly developing technology from high speed computer systems to the high resolution remote sensing sources of global coverage, we have developed the Dynamic Land Ecosystem Model (DLEM), which couples biophysical, hydrological, major biogeochemical processes (C, N,  and P cycling) including trace gases emissions such as CO₂, N₂O, CH₄ , vegetation dynamics, natural and anthropogenic disturbances (e.g. land-use/land-cover change, intensive management on crops and forests, wild fire, insect and disease etc.) ,  and works at multiple scales in time step from daily to yearly and spatial coverage from meters to kilometers, from region to globe across Earth’s land surface and in adjacent ocean regions.  The DLEM model consists of five core components: 1) biophysics, 2) plant physiology, 3) soil biogeochemistry, 4) dynamic vegetation, and 5) disturbances, land use and management. Here we present the key features of DLEM and its applications at multiple scales from site to global, including quantifying global and regional patterns of terrestrial gross and net primary productivity, evapotranspiration, land-to-atmosphere exchange of major greenhouse gases (CO₂, CH₄ and N₂O), land-to-ocean delivery of water, carbon and nutrient, etc.