Studies on the response of trees to drought- and heat-stress under climate changes

1.对光合作用过程的影响研究了马尾松(Sp)、马尾松(Sm)、佛罗里达角果(Cf)、鹅掌柴(Lt)和锯缘栎树(Qs)对高温和水分胁迫的响应。在40ﾟC作用下，Sp的碳氧基化效率和光子产率下降，Cf和Th的气孔电导受到抑制，处理后恢复。这种作用在Qs上很少观察到。由于高温和水分胁迫的综合作用，Sm和Cf的光合作用在较单一胁迫条件下受到抑制。2.高温40ﾟC处理生殖器官的热效应不影响辣椒的营养生长，但降低了其生殖生长。3.干旱伤害数学模型该模型由蒸散、吸水、土壤水分变化和叶片热收支四个子模型组成。据推测，这种伤害是由叶温和脱水引起的。在假定白杨生理参数的基础上，当气温高于38ﾟC时，白杨林分叶面积指数为6，有效土层厚度为50 cm时，经过2周的无雨期，即可发生干旱危害。4.利用高分辨率卫星数据，研究了树木的应力监测方法。水热胁迫处理使Sp 15 nm红边向短波方向移动。胁迫指数的增加与光合作用速率和气孔导度的降低有关。

1.Effects on photosynthetic processes The responses to heat and water stress were studied for Stewartia pseudocamellia (Sp), Stewartia monadelpha (Sm), Cornus florida (Cf), Liriodendron tulipifera (Lt) and Quercus serrata (Qs). Carbo-oxylation efficiency and photon yield of Sp decreased on 40ﾟC.Stomatal conductance of Cf and Lt was suppressed and recovered after treatment. The effect was seldom observed on Qs. Due to complex effect of heat and water stress, the photosynthetic processes of Sm and Cf were inhibited under the more mild condition than single stress.2.Heat effects on reproductive organ Treatment of high temperature 40ﾟC did not affected the vegetative growth of Capsicum frutescens, but decreased the reproductive growth. The mechanism of the effects on reproductive organ was studied through the analysis of assimilation and allocation.3.Mathematical model on drought injury The model was composed of the sub-models of evapo-transpiration, water uptake, changes of soil moisture and heat budget of leaf. The injury was assumed to be caused by leaf temperature and dehydration. On the assumption of the physiological parameters of Populus alba, heat injury was caused on the higher air temperature than 38ﾟC.If LAI of stand of Populus alba is 6 and available soil thickness is 50cm, drought damage was caused after 2 weeks of rainless period.4.Stress-monitoring The method of stress-monitoring of trees was studied for the use of the high-resolution satellite data. The treatment of water- and heat-stress shifted the red edge of Sp 15nm to the side of short wave region. The increase of stress index was correlated to the decrease of photosynthetic rate and stomatal conductance.