![]() ![]() ![]() Mean annual CH 4 uptake in tropical forest ecosystems ranged from 3.33 kg C ha −1 year −1 to 57.49 kg C ha −1 year −1, and net CH 4 sinks in tropical Montane tree forests ranged from 0.6 kg C ha −1 year −1 to 5.9 kg C ha −1 year −1 in southern Ecuador. Average soil N 2O emissions varied from 1.5 kg N ha −1 year −1 to 6.07 kg N ha −1 year −1 in tropical forests. For instance, soil CO 2 emissions ranged from 1.45 t C ha −1 year −1 to 13.74 t C ha −1 year −1 in subtropical forests of China, to 10.80 t C ha −1 year −1 to 11.75 t C ha −1 year −1 in subtropical Australian rainforests, and 25.60 t C ha −1 year −1 in tropical Thailand forests. To further our understanding of the patterns of C and N cycles and influential factors, we need to study the soil GHG emissions and their ability to mitigate global warming.Ī large number of studies have been conducted about tropical forest soil GHG emissions. In China, the plantation area increased by 5.1 million ha per year during the period from 2004–2008 it is expected that 40 million hectares plantation will be established within the period from 2005 to 2020. China accounts for 24% of the global forest plantations. In some countries (e.g., China, India, Russian Fedration, US, Japan, etc.), plantations represent an important part of the national forested areas, and are increasing at the rate of 3–4.5 million hectare per year. On the contrary, they are also the source of N 2O. Forest soils are the sink of carbon in the world and contain about 704 Pg C, with varying C densities under different environmental conditions. The emissions of greenhouse gases (GHGs) are mostly related to the carbon (C) and nitrogen (N) cycle from forest soils. These results implied that older forest stands might cause more GHG emissions from the soil into the atmosphere because of higher litter/root biomass and soil carbon/nitrogen content compared with younger stands.Įstablishment and management of forest plantations play an increasingly important role in sequestrating carbon from the atmosphere as one of the major strategies for mitigating global warming. Soil temperature had a significantly positive effect on CH 4 uptake and N 2O emission, whereas no significant correlation was found between CH 4 uptake and soil water content, and N 2O emission and soil water content. A clear exponential correlation was found between soil temperature and CO 2 emission, but a negative linear correlation was found between soil water content and CO 2 emission. The soil was a source of CO 2 and N 2O and a sink of CH 4 with annual emissions of 5.5–7.1 Mg C ha −1 year −1, 0.15–0.36 kg N ha −1 year −1, and 1.7–4.5 kg C ha −1 year −1, respectively. To elucidate the effect of plantation age and environmental factors on soil GHG emissions, we used static chamber/gas chromatography (GC) system to measure soil GHG emissions in an alluvial island in eastern China for two consecutive years. However, soil greenhouse gas emissions in dawn redwood ( Metasequoia glyptostroboides) stands of different ages are poorly understood. Greenhouse gas (GHG) emissions are an important part of the carbon (C) and nitrogen (N) cycle in forest soil. ![]()
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