Spatial and temporal dynamics of forest aboveground carbon stocks in response to climate and environmental changes

Abstract

Purpose Climate change, especially global warming due to rising atmospheric carbon dioxide (CO2) concentration, has attracted much attention in the past century. Increasing efforts have been made to find solutions to mitigate the CO2 emission and sequester the existing CO2 in the atmosphere into land-based ecosystems. Forest ecosystems are the best effective way to fix the atmospheric CO2 by photosynthesis and allocate to tree biomass and into soils. Meanwhile, trees or forests will also respond to gradually increasing CO2 concentration and environment changes. It is important to quantify the dynamic interaction between the changing environment and activities of carbon (C) accumulation by forests with a proper method and also assess the status of the forest C stocks in response to climate and environmental changes. Results and discussion Estimation of forest aboveground C stock still experiences much uncertainty, even for the same forest ecosystem such as in the tropics, due to the different methods used. Most of the work has been based on inventory data and allometric equations to estimate biomass and calculate C stock by multiplying a C content coefficient. Great uncertainties exist because of the representativeness of the allometric equations, the differences in C content for different tree species, and the spatial heterogeneous nature of C distribution in the forest ecosystems. The development of remote sensing has stimulated applications of the technology in estimating forest aboveground C stocks at a larger scale. Remote sensing can reduce the uncertainty of spatial variations caused by extrapolation with the inventory methods, but it has the limitation of lacking the ability to express the processes involved in C accumulation and their responses to the changing environment. Tree growth and climate change information embedded in tree rings can be a good supplement to interpret the results acquired by the remote sensing technique. Conclusions and perspectives The application of remote sensing techniques offers a practical method for C stock estimates in forest ecosystems in the context of spatial variations. However, the long-term responses of forest C accumulation to the gradually changing environment and climate are still not well understood. Integrated study of combining remote sensing and ecological research techniques in forest ecosystems is necessary for future study to explore the mechanisms of interaction between forest development and the gradual changing environment and also to assess the C sequestration status and potential of forest ecosystems under climate change.