摘要
应用2003年11月-2004年10月晴好天气涡度相关通量观测资料，对西双版纳热带季节雨林CO2交换的日变化和季节变化进行分析。结果表明：雾凉季、干热季和雨季的净生态系统CO2交换（NEE）均呈现出单峰型曲线的日变化趋势，昼间其变化规律较强，夜间呈波动状态。昼间NEE（取绝对值）雾凉季和雨季均显著大于干热季；夜间NEE雨季显著大于干热季，而干热季显著大于雾凉季。光合有效辐射是影响NEE日变化的主要因素，但不是造成季节差异的主要因素；饱和水汽压差和气温对NEE的季节差异有较大贡献。另外，应用Michaelis-Menten模型对昼间不同饱和水汽压差和气温下NEE对光合有效辐射的响应进行分析，结果表明：各季节较高饱和水汽压差下的表观最大光合速率（Pmax）、表观暗呼吸速率（Re）比较低饱和水汽压差下的Pmax、Re大，而表观光量子产额（α）则相反。各季节较高气温下的Re比较低气温下的Re大；雾凉季气温的差异对Pmax和α的影响较小；干热季和雨季较高气温下的α较小。
Tropical forests play an important role in altering the carbon budgets of terrestrial ecosystems. We examined patterns of diurnal and seasonal net ecosystem CO2 exchange （NEE） in a tropical seasonal minforest of Xishuangbanna on clear days between November 2003 and October 2004. We found that the diurnal dynamics of NEE showed a single-peaked curve. During daytime throughout the year, NEE increased with solar radiation after sunrise, but fluctuated after sunset. Values of NEE （absolute values） in the foggy-cool and wet seasons were greater than those in the dry-hot season during daytime. During the night, NEE values were dominated by soil temperature and soil water content and were highest in the wet season, followed by those in the dry-hot season and lowest in the foggy-cool season. NEE, water vapor deficit （VPD） and air temperature （Ta） curves all showed pronounced seasonal variation, but photosynthetically available radiation （ PAR ） did not vary significantly. Maximum photosynthesis rates （Pmax） and dark respiration rates （Re） were greater when VPD≥16 hPa than when VPD 〈 16 hPa, whereas photon density （α） was the opposite. Re was also greater when Ta≥ 25 ℃ than when Ta 〈 25 ℃ in the three seasons, a was reduced when Ta ≥ 25 ℃ in the dry-hot and wet seasons. The Pmax increased in the dry-hot season and decreased in the wet season when Ta≥ 25℃. Our data suggested that PAR is the main factor influencing NEE diurnal dynamics, whereas both VPD and Ta play a major role in regulating NEE seasonal dynamics.
出处
《植物生态学报》
CAS
CSCD
北大核心
2006年第2期295-301,共7页
Chinese Journal of Plant Ecology
基金
中国科学院知识创新重大项目(KZCX1_SW_01_01A4)
国家973项目(2002CB412501)
关键词
净生态系统CO2交换
涡度相关
日变化和季节变化
热带季节雨林
西双版纳
Xishuangbanna tropical seasonal rainforest, Net ecosystem CO2 exchange, Eddy covariance, Diurnal and seasonal variation
