Flux Dynamics of CO<sub>2</sub> in a Rubber Plantation in Xishuangbanna <?A3B2 pi6?>and Its Influencing Factors

<p indent="0mm">Rubber plantations are important artificial forest ecosystems in tropical regions of China, and accurate assessment of their carbon source and sink status is crucial.Based on the carbon flux observation from Xishuangbanna rubber plantation ecosystem from 2012 to 2016, the dynamic of CO₂ flux in rubber plantations and its influencing factors using correlation analysis and multiple stepwise regression methods were analyzed. The results showed that: 1) net ecosystem carbon exchange (NEE) in the study area was positive (indicating carbon emission) from January to February and negative (indicating carbon absorption) from March to December. NEE, ecosystem respiration (<italic>R</italic>_eco), and gross primary productivity (GPP) exhibited obvious seasonal variations, with stronger values during the rainy season and weaker values during the dry season. 2) The rubber plantation ecosystem acted as a ″carbon sink″ status for five consecutive years, with the multi-year average NEE being <sc>–564.68±65.20 g C/(m²·a),</sc> indicating a higher carbon sink capacity compared to other tropical forests. <sc>3) Environmental</sc> driving factors of NEE varied in different seasons. At the monthly scale, vapor pressure explained 51.8% of NEE variations during the wet season, while soil temperature explained 38.9% of NEE variations during the dry season. Leaf area index did not adequately explain variations in NEE, <italic>R</italic>_eco, and GPP. NEE during the wet season in rubber plantations was almost three times that during the dry season, and the concentrated leaf turnover of rubber trees in January to February due to cold stress had a significant impact on NEE during the dry season.