Scientists reveal trends in carbon storage and sequestration across Chinese ecosystems

Climate change is a one of the biggest challenges facing humanity. The Paris Agreement, adopted in December 2015, became the second legally binding climate agreement after the Kyoto Protocol, and coordinates global efforts to combat climate change.

As a party to the Paris Agreement and the largest developing country, China has adjusted economic development models and promoted technological progress in energy conservation.

However, with rapid economic development, it is difficult to achieve deeper cuts in greenhouse gas emissions. China is facing growing pressure to achieve its goals associated with the Paris Agreement.

Carbon sequestration by terrestrial ecosystems is one of the most economically and environmentally friendly ways to mitigate atmospheric CO₂ concentrations. How to improve carbon storage and carbon sequestration of terrestrial ecosystems is not only a cutting edge field within global change research, but also the key scientific foundation for the mitigation of climate change.

Led by Professor FANG Jingyun from the Institute of Botany of the Chinese Academy of Sciences (CAS), together with collaborators, the ecosystem carbon sequestration project team was set up.

Under the framework of the five-year Strategic Priority Research Program "Climate Change: Carbon Budget and Relevant Issues" initiated by CAS in January 2011, the team aims to quantify the magnitude and distribution of ecosystem carbon pools and sequestration in China's terrestrial ecosystems.

From 2011 to 2015, the project team conducted an intensive nationwide field study of vegetation, soils and habitats using consistent research designs and protocols.

This study involved more than 350 researchers, covered more than 17,000 quadrats of China's terrestrial ecosystem, including forests, grasslands, shrubs, and farmland, and collected approximate 600,000 vegetation and soil samples.

Since January 2015, Prof. FANG has led the research group to use datasets from the study to answer questions of interest to scientists and policymakers in the fields of global change, the carbon cycle and general ecology.

The group recently published seven papers for a special feature in PNAS entitled "Climate change, human impacts, and carbon sequestration in China." The work represented a prodigious effort and important scholarly accomplishment.

In this special feature, the research group clarified the structure and function of China's terrestrial ecosystem and its response to climate change and human activity; quantified the intensity and spatial distribution of carbon sequestration capacity in China's terrestrial ecosystem; and quantified the effects of biodiversity and nutrient conditions on the productivity of the ecosystem on a macro scale.

They showed that four major terrestrial ecosystems (forest, grassland, shrubland, and cropland) stored a total of 94.4 petagrams (Pg) of carbon and sequestered a total of 201.1 teragrams (Tg) of carbon per year from 2001-2010.

The forest, shrubland, and cropland ecosystems are significant carbon sinks, but the grassland ecosystem is a very weak carbon source. These carbon stock changes are largely attributed to climate change, ecological restoration projects, and cropland management.

The team also showed that species diversity and species traits play a strong role in managing soil carbon storage and gross primary production is closely coupled with patterns of nitrogen and phosphorus stoichiometry.

Studies described in this special feature demonstrate that climate and land-use changes have profoundly altered the structure and function of China's terrestrial ecosystems and their carbon storage.

Restoration regimes and agricultural management practices that integrate economic and policy-incentives were particularly effective in facilitating ecosystem carbon sequestration.

These findings provide new insights into the role of human intervention in facilitating ecosystem carbon storage and offer useful lessons to other developing countries that are experiencing similar economic and social transformation.

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The work was supported by the five-year Strategic Priority Research Program "Climate Change: Carbon Budget and Relevant Issues" initiated by CAS.

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