Water consumption and carbon capture by trees of an evergreen and a deciduous mountain forest as functional indicators of slow environmental changes in South Ecuador

这一转让项目开发了厄瓜多尔南部一片常绿山林中全球变化影响的多因素指标原型模块。它使用树木的水和碳关系作为微妙的环境变化的主要功能指标，这是无法直接观察到的。树木对碳的吸收和蒸腾作用引起的水分损失被耦合为水分利用效率(WUE)，作为一个参数，它集成了两个生态生理过程，应该对环境条件表现出高度的敏感性。项目C5基于一个新的模型，允许计算整个树冠的净二氧化碳吸收。模型的参数化用了树叶气体交换数据、树木总耗水量和树冠结构数据(由项目C6提供)。与C6项目合作，在森林中建立了一个研究地块(10x100米)，包括两个塔(30米和36米高)，每个塔有两个平台。这些平台用于在八棵树的树冠上进行气体交换测量。这些树和塔之间延伸的另外13棵树都配备了树液流量传感器，用于连续长期测量日常用水量。对不同树种的水分利用效率(WUE)等重要生理参数进行了测定，不同树种因其功能类型不同对环境变化表现出不同的敏感性。此外，树冠比WUE和树木的总耗水量将被用来计算总的光合净碳收益。所描述的测量将得到关于茎生长、叶片寿命和长期水分关系的数据的补充(13C辨别数据)。由于行政和后勤问题，第一次测量仅在1.5年前开始。对于长期的季节性比较以及对短期变化和长期趋势的区分，至少需要连续两年的测量。已有18个月数据的三个树种的用水量减少，这可能归因于降雨量和相对湿度的增加。这一趋势和树种的不同敏感性应该用剩余的8个树种(18棵树)来证明，这些树种的数据到目前为止已经有9个月或11个月了。项目C6借助闪烁计调查了两个塔之间的树冠上的蒸散，这一方法需要项目C5的数据来解释。项目C5和C6的结合将导致制定山地热带雨林指标。

This transfer project develops a module of a multifactorial indicator prototype for global change effects in an evergreen mountain forest in South Ecuador. It uses water and carbon relations of trees as primary functional indicators of subtle environmental changes, which cannot be observed directly. Acquisition of carbon by a tree and its concomitant water loss by transpiration is coupled as water use efficiency (WUE), which as a parameter integrates two ecophysiological processes and should exhibit a high sensitivity to environmental conditions. The project C5 is based on a new model allowing computation of the net CO2 uptake by the entire crown. Parameterization of the model is by data of leaf gas exchange, total water consumption of the tree, and structural data of the crown (provided by project C6). In collaboration with project C6, a study plot (10 x 100 m) was established in the forest, including two towers (30 and 36 m high) with two platforms each. The platforms are used for campaigns of gas exchange measurements in the crowns of eight trees. These trees and 13 more on the stretch between the towers are equipped with sap flow sensors for continuous long-term measurements of the daily water consumption. WUE and other tree-specific physiological important parameters like the unexpected high nocturnal transpiration are measured on different tree species which according to their functional type exhibit different sensitivity to environmental changes. Furthermore, the crown specific WUE and the total water consumption of the trees will be used to calculate total photosynthetic net carbon gain. The described measurements will be supplemented by data on stem growth, longevity of leaves and long-term water relations (13C discrimination data). Due to administrative and logistic problems, first measurements started only 1.5 years ago. For the long-term seasonal comparison and the differentiation between transitory changes and long-term tendencies, continuous measurements are required for at least two years. The three tree species where data are already available over 18 months showed a decreasing water consumption which could be attributed to an increase in precipitation and relative humidity. This tendency and the different sensitivities of tree species should be proven with the remaining 8 tree species (18 trees) from which data are available so far for 9 or 11 months.Project C6 investigates evapotranspiration above the canopy on the stretch between the two towers with the help of a scintillometer, an approach which requires the data from project C5 for interpretation. The combination of the projects C5 and C6 will result in the development of the indicator for the mountain rain forest.