Long-term Monitoring of Forest Carbon Dynamics in the East Asia Forest Dynamics Plots Network

V.N. Sukachev Institute of Forest, Siberian Branch, Russian Academy of Science, Russia

National University of Mongolia, Mongolia

Forestry Administration (FA), Cambodia

Universitas Mulawarman, Indonesia

Forest Research Institute Malaysia (FRIM), Malaysia

Chulalongkorn University, Thailand

Kasesart University, Thailand

FY 2014–2017 Global Environment Research Coordination System (Ministry of the Environment, Japan)

SATO, Tamotsu

Recent evidence of global warming has raised awareness about the importance of mitigation practices to reduce or avoid the threats of climate change. The reduction of emissions from deforestation and forest degradation and the fostering of conservation, the sustainable management of forests, and the enhancement of forest carbon stocks in developing countries (REDD+) is a cost-effective way of reducing greenhouse gas emissions. However, the measurement, reporting, and verification (MRV) of forest carbon change are indispensable for REDD+ implementation. Therefore, a robust, cost-efficient, and transparent MRV system is required to ensure that the benefits of REDD+ are realized.
The long-term monitoring of forest dynamics can help us to estimate changes in forest carbon stocks more accurately and can contribute to the development of MRV methodologies for the implementation of REDD+. Furthermore, networks of monitoring plots provide the opportunity for global comparisons and the synthesis of research that could not be accomplished with individual plots.

The aims of this project were to:
1) Collect highly accurate forest carbon stocks data in East Asia.
2) Compare annual fluctuations in forest carbon stocks using monitoring data.
3) Develop measuring methods for carbon stocks with low uncertainties.

In the last few decades, the Forestry and Forest Products Research Institute (FFPRI) has established large-scale and long-term research sites for monitoring forest dynamics in Japan and East Asia in collaboration with many foreign research institutes and universities. In 2009, FFPRI created the East Asia Forest Dynamics Plots Network (EA-FDPN), which encompasses four forest types (boreal forest, tropical dry forest, tropical rainforest, and tropical swamp forest) from Siberia to the Equator.
 The EA-FDPN data allowed us to make more precise estimates of the carbon pools in East Asian forest ecosystems, and the analysis of data from five carbon pools within a broad range of forest types provided us with new insights into both spatial and temporal variations in carbon pools under different climatic and site conditions. We estimated the carbon stocks in the above- and belowground (ABG) tree biomass and aboveground net primary production (ANPP) in 14 monitoring plots since FY2014, and also measured a non-tree species carbon pool, such as the herb layer or bamboo biomass, in tropical dry forests.

Carbon stocks in tree biomass varied among the monitoring sites, exhibiting a general tendency to decrease with increasing latitude. Thus, the boreal forest sites showed relatively low carbon stocks (e.g., 20 Mg C/ha in Tura, Russia; and 60 Mg C/ha in Udleg, Mongolia), while tropical rainforest ecosystems had high carbon stock values, ranging from 250 to 300 Mg C/ha. In addition, monitoring sites that lacked severe disturbances (e.g., Pasoh and Semangkok) showed fewer fluctuations in biomass (Fig.) and ANPP during the monitoring period. However, there were no clear differences in AGB or ANPP between non-selective and selective logging sites in Bukit Soeharto after 2015, which may have been due to the drought associated with the El Niño Southern Oscillation (ENSO) event in 2014–2015 causing tree mortality. Finally, our results implied that inclusion of the biomass of non-tree species such as bamboo, palm, and dense herbs is indispensable for making precise carbon stock estimates in tropical forest ecosystems.

Fig. Forest carbon pools in tropical dry forests

Twenty-five years of seed production monitoring in Pasoh Forest Reserve have shown that the number of water stress days in the first quarter (January to March) changes cyclically and generally triggers flowering. This masting cycle begins in a wet year when there is no water stress in the first quarter. The findings of the present study will contribute to the development of methods for selective logging and sustainable seedling production in nurseries.

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