青藏高原东部生态系统土壤碳排放

在青藏高原探讨不同生态系统碳平衡规律及其影响因子并揭示其对全球含碳温室气体变化的影响与响应,有重要的现实意义和理论价值。分别在海北高寒草甸生态站、贡嘎山森林生态站和拉萨农业生态站用静态箱法进行了土壤CO₂排放的试验研究。土壤CO₂排放速率日平均值为草甸215.87～329.68mgCO₂m^-2h^-1,森林713.72～2102.56mgCO₂m^-2h^-1,农田913.05～1135.83mgCO₂m^-2h^-1。土壤碳排放速率日变化,在农田和高寒草甸区表现为单峰型,均以地方时8∶00～16∶00最高,0∶00～8∶00最低。草甸、农田土壤碳排放随着牧草、作物生长发育的加速而逐渐增加,越接近成熟(或枯黄期)其值越低,林区以6～9月的生长旺季为最高。土壤碳排放与温度之间有较好的相关性,温度是影响土壤碳排放的重要因子,全球变暖有可能引起高原土壤碳排放的增加。

Soil carbon emission from ecosystems of eastern Qinghai Tibet Plateau

It is of practical significance and important scientific value to probe into carbonic balance in different ecosystems and its environmental factors affecting it,and to reveal its influence on and response to the changes of global carbonic greenhouse.Experimental studies of soil CO2 emission flux by enclosed chamber technique were conducted at Haibei Frigid Meadow Ecological Station,Gongga Mountain Alpine Forest Ecological Station,and Lhasa Agroecological Station.The diurnal mean value of soil CO2 emission flux was 215.87～329.68 mg CO2m－ 2h－ 1 in highland meadows,713.72～2,102.56mgCO2m－ 2 h－ 1 in alpine forests,and 913.05～1,135.83mgCO2m－ 2h－ 1 in farmlands.Daily change of soil CO2 emission flux showed a single peak in farmlands and growing frigid meadows,both reached the highest at local time of 8∶ 00 to 16∶ 00,and the lowest from 0∶ 00 to 8∶ 00. In farmland and meadow,soil CO2 emission increased along with the accelerating growth of crops and pasturage.Before closing to the ripening period,the value went down.However in forest area,the highest value of soil CO2 emission reached to a peak from June to September.We found that there was a good correlation between temperature and soil CO2 emission,and temperature appears an important factor affecting soil CO2 emission,so the global warming will very likely increase soil CO2 emission.