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蒸腾是植物重要的生理活动之一,受多种环境因子的影响。本文基于改进的Jarvis-Stewart模型研究洞庭湖流域3个树种(桂花树(Osmanthus fragrans)、樟树(Cinnamomum camphora)和枫香(Liquidambar formosana))的蒸腾对环境因子(太阳辐射、饱和水汽压差(VPD)和土壤水势)的响应,比较不同环境因子对3种树蒸腾的影响并讨论VPD对植物蒸腾的双重影响。结果表明:(1)桂花树和枫香的蒸腾对太阳辐射的反应比樟树迅速,樟树的蒸腾对VPD的敏感度明显高于桂花树和枫香,樟树和枫香对水势的响应比桂花树更敏感,说明植物蒸腾对环境因子的响应有树种之差。(2)从生长季的平均值来看,2013年影响植物蒸腾的主导因子是水分条件,2014和2015年是VPD,说明决定植物蒸腾的主要是不同年份间的水文气象条件差异,与树种无关。(3)VPD对植物蒸腾既有促进作用又有限制作用。2013年(夏季干旱)VPD对植物蒸腾的双重影响非常明显,随着VPD值增加,VPD对蒸腾的促进作用增强;增加到一定值,VPD对蒸腾的限制作用随之增大。2014和2015年(降水多),VPD值比较小,VPD对植物蒸腾主要是促进作用。
Transpiration is one of the important physiological activities of plants, affected by a variety of environmental factors. In this paper, based on the improved Jarvis-Stewart model, the effects of transpiration of three tree species (Osmanthus fragrans, Cinnamomum camphora and Liquidambar formosana) on the environmental factors (solar radiation, saturated vapor pressure difference VPD) and soil water potential. The effects of different environmental factors on the transpiration of three trees were compared and the dual effects of VPD on plant transpiration were discussed. The results showed that: (1) The transpiration of osmanthus fragrans and Liquidambar formosana responded faster to solar radiation than camphor, and the sensitivity of camphor to transpiration of VP was higher than that of osmanthus fragrans and sweetgum. More sensitive, indicating that the response of plant transpiration to the environmental factors species differences. (2) According to the average growth season, the dominant factor affecting plant transpiration in 2013 is the water condition, and the 2014 and 2015 are VPD, indicating that the main determinants of plant transpiration are differences in hydrometeorological conditions and tree species . (3) VPD has both promoting and limiting effects on plant transpiration. The dual effect of VPD on plant transpiration in 2013 (summer drought) is very obvious. With the increase of VPD, the promoting effect of VPD on transpiration is enhanced. When it reaches a certain value, the restriction effect of VPD on transpiration increases. In 2014 and 2015 (with heavy rainfall), the VPD value was relatively small, and VPD had a major role in promoting plant transpiration.