Seasonal variation in the leaf gas exchange of tropical forest trees in the rain forest–savanna transition of the southern Amazon Basin
Seasonal variation in the leaf gas exchange of tropical forest trees in the rain forest–savanna transition of the southern Amazon Basin
复制标题
亚马逊盆地南部雨林-稀树草原过渡区热带森林树木叶片气体交换的季节变化
DOI：
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发表时间：
2005
影响因子：
1.4
通讯作者：
Shozo Shiraiwa
中科院分区：
文献类型：
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作者：
E. Miranda;G. Vourlitis;N. P. Filho;Pedro Correto Priante;J. H. Campelo;G. S. Suli;C. L. Fritzen;F. Lobo;Shozo Shiraiwa
在2000年7月至2003年9月期间，对巴西马托格罗索州锡诺普雨林-稀树草原过渡区亚马逊半落叶林树木的光合光响应进行了测量，以检验适应不同生长光环境的树木在旱季的光合能力会下降的假设。最大光合作用（Amax）和气孔导度（gmax）显着较高，在潮湿的季节，但对干旱的生理反应是不明确的功能的生长光环境。对于某些物种，如生长在树冠中部的九节属，在旱季内部叶片CO2浓度（Ci）低于30%以上，这表明Amax的下降部分是由于气孔限制CO2扩散造成的。对于其他物种，如生长在树冠顶部的Brosimum lactescens，生长在树冠中部的Tovomita schomburgkii和生长在下层的Dinizia excelsa，旱季Ci下降<20%，表明与CO2扩散无关的因素在限制Amax方面更重要。干旱季节gmax的下降似乎对维持某些物种更一致的叶水势很重要（T。schomburgkii和D. excelsa），而不是其它（Psychotria sp.）。这些结果表明，虽然季节性干旱对半落叶亚马逊森林树木的生理能力产生了重要的限制，但这种限制的机制可能因物种而异。
The photosynthetic light response of Amazonian semi-deciduous forest trees of the rain forest–savanna transition near Sinop Mato Grosso, Brazil was measured between July 2000 and September 2003 to test the hypothesis that the photosynthetic capacity of trees acclimated to different growth light environments will decline during the dry season. Maximum photosynthesis (Amax) and stomatal conductance (gmax) were significantly higher during the wet season; however, the physiological response to drought was not a clear function of growth light environment. For some species, such as Psychotria sp. growing in the mid-canopy, internal leaf CO2 concentration (Ci) was >30% lower during the dry season suggesting that declines in Amax were caused in part by stomatal limitations to CO2 diffusion. For other species, such as Brosimum lactescens growing at the top of the canopy, Tovomita schomburgkii growing in the mid-canopy, and Dinizia excelsa growing in the understorey, dry season Ci declined by <20% suggesting that factors independent of CO2 diffusion were more important in limiting Amax. Dry-season declines in gmax appeared to be important for maintaining a more consistent leaf water potential for some species (T. schomburgkii and D. excelsa) but not others (Psychotria sp.). These results indicate that while seasonal drought exerts an important limitation on the physiological capacity of semi-deciduous Amazonian forest trees, the mechanism of this limitation may differ between species.