崇明岛新围垦区不同土地利用条件下的土壤呼吸研究

Research on soil respiration of different use-lands in new reclaimed soils in the Chongming Island

土地利用方式是影响温室气体减排的关键因子之一。新围垦土地因其土壤本底均一、土地利用历史简单短暂,使得评价短期土地利用对温室气体排放的影响成为可能。为此,在崇明东滩湿地新围垦区选取了本底均匀、利用历史简单的几种土地利用类型(旱田、水旱轮作农田、人工林带),研究其土壤呼吸的变化及其与土壤环境间的关系,以期评价其各自的固碳和温室气体减排潜力。研究表明,2009年整个春季,土壤呼吸速率强度的顺序为水旱轮作[(0.30±0.08)mol.m-2.d-1]>旱田[(0.18±0.04)mol.m-2.d-1]>林带[(0.09±0.01)mol.m-2.d-1];春季各月份,水旱轮作田土壤呼吸速率变化波动较大,旱田较平稳,4、5月份最先达到日最高值,人工林带最为平稳,且始终具有较低的呼吸强度;旱田土壤呼吸速率均不能简单用土壤5 cm处温度及湿度进行解释,林带与水旱轮作田土壤呼吸速率与土壤5 cm处温度显著相关(P<0.05);整个春季,林带土壤呼吸与5 cm处温度及湿度均显著相关,其中与温度极显著相关(P=0.01),水旱轮作田与旱田的土壤呼吸速率与两者均不相关。

Land-use change is a crucial factor in regulating soil C processes with a potential to mitigate green house gases emission by fossil fuel combustion.The soils of new reclaimed wetland have a relatively homogeneous background and short and clear history of land-use.These make the evaluation of the effect caused by short-time land use on greenhouse gas emissions possible.Various sites（new reclaimed） in eastern Chongming Island of different land use,including dry-land,flood drought rotation field（rotation of barley and paddy rice）,forest belt（Citrus reticulata） were selected.In the whole spring,our results suggest that the order of the rate of soil respiration is flood drought rotation field（0.38±0.08） mol.m-2.d-1 dry-land（0.18±0.04） mol.m-2.d-1 forest belt（0.09±0.01） mol.m-2.d-1.It was found that the daily rate of soil respiration of flood drought rotation field fluctuated obviously,which of forest belt was more stable and lower,the daily rate of soil respiration of dry land was the first to reach the daily maximum in May and April.The daily rates of soil respiration of forest belt and flood drought rotation field were completely consistent with the temperatures under soil 5 cm,while dry-land had no obvious correlation with the temperature.In the whole spring,the rate of soil respiration of forest was consistent with the temperature under soil 5 cm and soil moisture but both dry-land and flood drought rotation field couldn’t explained well by them.