摘要
通过实地观测和模型模拟的方法,研究了云杉林地的CO2源汇的日变化和年变化,结果表明:(1)云杉光合速率在白天呈现明显的双峰曲线,即存在明显的光合“午休”现象。光合速率最高出现在10时和15时,分别达到了13.96和13.24μmol·m-2·s-1,白天光合速率的最低点出现在20时,为2.52μmol·m-2·s-1。晚间植物呼吸的平均速率为2.65μmol·m-2·s-1。(2)云杉林地土壤呼吸速率在白天明显要高于夜间,最高土壤呼吸速率出现在19时,达到了CO21.42g·m-2·h-1。土壤呼吸速率最低值出现在22时,CO2为0.48g·m-2·h-1。夜间土壤呼吸速率相对较为稳定,维持在CO20.6～0.8g·m-2·h-1之间,平均值为CO20.70g·m-2·h-1。(3)夜间云杉生态系统总的来说是碳源,白天随着气温、光强等环境因素的变化,碳源/碳汇关系有着一定的不确定性。总体来看云杉林地生态系统24小时净释放CO24.22g·m-2·d-1,因此8月份,云杉林地生态系统应该是一个碳源;通过模型预测的结果表明云杉林地生态是一个极弱的碳源,年释放量为CO28.20t/hm2。
In this paper,the daily and annual changes of CO2 source/sink of the forestland ecosystem of Picea schrenkiana in the Tianshan Mountains are researched through the field observation and simulation with a model by measuring the photosynthesis rate of Picea schrenkiana with CIRAS-1 photosynthetic meters. The study area is located in the southwest from the Tianchi Lake in the Tianshan Mountains,the height and age of the tress of Picea schrenkiana vary in ranges of 20~25 m and 30~100 years respectively,and the average canopy density is 0.75; the slope direction and degree are NE and 35°,and the elevation is 2 120 m a.s.l. The soil is gray-brown forest soil with a thickness of about 40 cm. The under-forest plants are dominated by Agegopodium alpestre, Poe nemoralis,Polygonum viviparum,Alchemila tianschanica,etc,and the height varies in a range of 2~20 cm. The result shows that the net CO2 release of the forestland ecosystem of Picea schrenkiana in 24 hours in August is 4.22 g/m2. So it is considered that the forestland ecosystem of Picea schrenkiana is a CO2 source in August. The predicted result with the model shows that the forestland ecosystem of Picea schrenkiana is an extremely poor carbon source,and the annual CO2 release is 8.20 t /hm2.
出处
《干旱区地理》
CSCD
北大核心
2005年第2期244-247,共4页
Arid Land Geography
基金
国家自然基金(40071009)
中科院创新项目KZCX3-SW-326/327
国家重点基础研究发展规划项目2002CB12508
土壤学自治区重点学科资助
