森林生态系统叶片暗呼吸时空动态及其影响因子

作为森林生态系统一个重要的呼吸通量，叶片呼吸在森林碳循环中扮演着重要的角色。开展叶片呼吸的机理及其影响因子研究，有助于构建大气和植被之间的呼吸通量模型，预测分析气候变化对森林生态系统生产力和碳源汇功能的影响。通常采用Li - 6400光合测定系统和LAI - 2000树冠分析仪测定森林生态系统叶片呼吸速率。叶片呼吸是一个复杂的生物化学过程，受到大气温度、CO₂浓度、土壤水分、叶片寿命、叶龄、比叶面积、叶片氮含量等多种因子的影响。叶片呼吸的日变化通常呈单峰曲线，与温度变化大体一致; 生长季早期和晚期的呼吸速率通常高于中期; 叶片在冠层着生位置影响其呼吸速率，冠层上部叶片的呼吸速率要高于冠层下部叶片。今后叶片呼吸研究应围绕以下4个关键问题:1) 模型构建时需要考虑叶片呼吸的温度驯化;2) 叶片呼吸在昼夜交替时内在调节机制;3) 从叶片呼吸到冠层呼吸的尺度转化;4) 加强和完善叶片呼吸影响因子研究。

Leaf Respiration Variations and Its Controlling Factors in Forest Ecosystem

Plant leaves respiration plays an important role in forest carbon cycle as a vital respiration flux of forest ecosystem. The study on the mechanism mechanism of leaf respiration and its controlling factors will help establish the respiration flux model between air and vegetation and predict the impact of global climate change on productivity and carbon balance of forest ecosystem. Leaf respiration rate of forest ecosystem is usually measured using Li-6400 photosynthetic measurement system and LAI-2000 plant canopy analyzer. Leaf respiration is a complex biochemistry process, which is controlled by atmospheric temperature, CO₂ concentration, soil water content, leaf life-span, leaf age, leaf specific area, leaf nitrogen content and other factors. The daily variations of leaf respiration presents in unimodal curve, which is in line with the temperature change; the respiration rate is higher in the early and late growing season than in the middle; the position of leaf at canopy can influence the respiration rate, which is higher at the upper canopy than at the lower canopy. In the future, the study on leaf respiration is supposed to focus on following 4 critical points:(1) temperature acclimation of leave respiration, which need to be considered when modeling;(2) respiratory metabolism at the turn of day or night;(3) the shift of scaling from leaf to canopy;(4) strengthening the study on controlling factors to leaf respiration.