The Plant-mediated Methane Transport From Mangrove In Zhangjiang River Estuary

Trees are the important pathway of atmospheric methane transport form nature wetland and are known to contribute significently to methane emissions in wetland ecosystem.In this study,by using closed static chambers,we measured plant-mediated methane transport from the mangrove trees in Zhangjiang River estuary,which contained Kandelia obovata,Aegiceras corniculatum and Avicennia marina.Our results showed that:?1?The methane transport via stem from different mangrove species are different significently.The DBH?diameter at breast height?had significent effects to stem methane transport,which was positively correlated with the DBH.There was a significent power function relationships between the rate of tree-stem methane transport and wood specific density.The soil physicochemical property had significent effects on the stem methane transport rates.?2?Methane transport rates were decreased along the heigit of tree and there was a significent power function relationships between the rate of tree-stem methane transport rates and height.The methane transport rates of the stem,pneumatophore and the individual tree played significent season variation.The soil temperature,pH,TC,TN and pore water NO₃^--N,SO₄^2-,Cl^-contents had significent effects on the methane transport via mangrove plants.The methane transport rate from individual tree was positively correlated with air temperature.?3?The methane were transported via different parts of mangrove plants.The buttress roots of Kandelia obovata and pneumatophore of Avicennia marina accounted for82.7%and 95.8%of methane transport of the whole plant,respectively.The stem of Aegiceras corniculatum in 0.05²0cm had the strongest methane transport capacity and accounted for 32.3%of the whole plant methane transport.?4?The methane transport capacity of the mangrove populations and the ecosystem methane emission played significent season variation.The methane transport capacity of the mangrove populations from Kandelia obovata,Aegiceras corniculatum and Avicennia marina are 2.35±0.36 g·hm^-2·h^-1,1.28±0.47 g·hm^-2·h^-1,13.61±2.34 g·hm^-2·h^-1 and3.80±0.64 g·hm^-2·h^-1,1.59±0.45 g·hm^-2·h^-1,18.54±2.76 g·hm^-2·h^-1,respectively.The contributions of plant-mediated methane transport to ecosystem methane emissoin from different mangrove populations had significent season variation.The contribution of Kandelia obovata was highest?73.66%?in winter and Aegiceras corniculatum and Avicennia marina were highest?90.61%,84.49%?in summer.The contributions of plant-mediated methane transport to ecosystem methane emissoin from Kandelia obovata,Aegiceras corniculatum and Avicennia marina were 58.8%,42.1%and 59.7%.