中国滨海湿地互花米草群落甲烷通量研究的综述

A review on methane fluxes of Spartina alternifloracommunities in coastal wetlands of China

互花米草(Spartina alterniflora)具有较强的固碳作用,了解互花米草群落的甲烷通量可为评估互花米草的净碳汇功能提供重要参数。本文分析了我国滨海湿地互花米草群落CH4通量的总体特点和机制,结果表明:(1)不同地区互花米草群落CH4通量无明显规律且差异较大。不同生长环境下的环境因子对CH4排放有综合调控作用,其中很大部分是通过影响土壤中与CH4产生有关的微生物影响CH4通量。(2)互花米草群落CH4通量夏季最高、冬春较低;日通量则处于不规则的波动中,但总体白天通量高于夜晚。CH4通量季节差异与温度、生物量和光照呈正相关,温度影响参与CH4生成的微生物的活性,生物量为CH4产生提供有机质原料,光照则通过光合作用影响有机质的合成;日通量差异除与温度和光照有关外,最主要还受到潮汐变化的影响。(3)无潮水覆盖时CH4通量远大于有潮水覆盖时。有潮水覆盖时互花米草下部作为CH4排向大气的重要通道受阻,同时CH4被储存于土壤或排放到潮水中,落潮后才进入大气,因此CH4通量更低。(4)刈割会降低CH4通量。互花米草植株为CH4的产生提供了重要原料,同时利用通气组织将CH4排放到大气,刈割切断了CH4传输途径并减少了地上生物量,因此降低了CH4通量。

Spartina alterniflora has strong carbon sequestration.Understanding the methane fluxes of S.alterniflora communities can provide important parameters for assessing the net carbon sink function of S.alterniflora.This paper systematically summarizes the general characteristics and mechanism of CH 4 emission by S.alterniflora communities in coastal wetlands of China.Results show that(1)CH 4 flux in different regions shows no obvious patterns and differed significantly.Environmental factors in different environments have a comprehensive regulatory effect on CH 4 emission,and most of them affect CH 4 flux by affecting microorganisms related to CH 4 production in soil.(2)CH 4 flux is the highest in summer and lower in winter and spring.The diurnal flux is in irregular fluctuation,but the total daytime flux is higher than that at night.The seasonal difference of CH 4 flux is positively correlated with temperature,biomass and light.Temperature affects the activity of microorganisms involved in CH 4 production.Biomass provides organic matter for CH 4 production,while light affects the synthesis of organic matter through photosynthesis.In addition to temperature and light,the diurnal difference is mainly affected by tidal changes.(3)The CH 4 flux without water flooding is much greater than that with water flooding.In the tide stage,the lower part of S.alterniflora is blocked as an important channel for CH 4 emission to the atmosphere.At the same time,CH 4 is stored in the soil or discharged into the tide,and then to the atmosphere after ebbing tide.Therefore,the CH 4 flux is lower during flooding.(4)Mowing would reduce CH 4 flux.S.alterniflora provides an important raw material for CH 4 production,and simultaneously uses aerenchyma to release CH 4 into the atmosphere.Mowing cuts off the CH 4 transmission path and reduces the aboveground biomass and thus the CH 4 flux.