Tree diversity as a control of whole tree water use in experimentally assembled mixtures in Panama

随着天然热带森林的减少和前雨林地区的退化，可能会建立更多的热带树木种植园。到目前为止，它们通常由单一的外来快速生长的物种组成。人们对这类种植园的高用水率和不可持续的土壤养分耗竭非常关注，而且最近越来越关注。最近在热带地区重新造林的办法强调在混交林中建立本地物种。在巴拿马的一个实验性种植园中，以不同的多样性水平种植了在天然林中表现出不同相对生长率的本土树种。拟议的项目打算分析这些物种在不同的多样性水平（1-，3-，和6-物种混合物）的地块的全树水分利用，并分析土壤水分分配共存物种。这些方法包括土壤水文测量、树液流量分析和稳定同位素技术的应用。我们计划与一个研究树木养分收支的项目密切合作。总的来说，我们希望在树种多样性以及水和营养资源方面增加对退化热带地区生态无害的重新造林的了解。

As natural tropical forests diminish and former rain forest areas are being degraded, more tropical tree plantations may be established. Up to now, they usually consist of a single exotic fast growing species. There is much, and recently increasing concern about high water use rates and non-sustainable soil nutrient depletion by such plantations. Recent approaches to reforestation in the tropics emphasize the establishment of native species in mixed stands. In an experimental plantation in Panama, native tree species, which in natural forest exhibit different relative growth rates, were planted at different diversity levels. The proposed project intends to analyze the whole tree water use of these species in plots of different diversity levels (1-, 3-, and 6-species mixtures), and to analyze the soil water partitioning among cooccurring species. The methods include soil hydrological measurements, tree sap flux analyses and the application of stable isotope techniques (¿D). We plan to cooperate closely with a project studying the tree nutrient budget. Overall, we wish to increase the knowledge for an ecologically sound reforestation of degraded tropical areas with respect to tree species diversity and water and nutrient resources.