Forest floor water dynamics and root water uptake in four forest ecosystems in northwest Amazonia
Forest floor water dynamics and root water uptake in four forest ecosystems in northwest Amazonia
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DOI：
10.1016/s0022-1694(00)00302-4
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发表时间：
2000-11-21
影响因子：
6.4
通讯作者：
Dekker, S
中科院分区：
文献类型：
--
作者：
Marin, CT;Bouten, IW;Dekker, S
中卡克塔（哥伦比亚亚马逊河流域）未受干扰的森林生态系统的一个共同特点是，在高度风化和有效养分非常低的矿物质土壤上存在着厚的枯枝落叶层，有丰富的细根。在这些情况下，枯落物层或森林Boor（FF）可能在森林水分平衡中发挥重要作用，控制水分通量和养分循环。我们调查了四个代表性的森林生态系统在中部卡克塔，哥伦比亚亚马逊河流域（第三纪沉积平原，高阶地，低阶地和很少被淹没的洪泛平原）的森林地面水动态。每小时测量一次气象条件，在两年的时间内每天测量FF储水量、FF中的TDR含水量和凋落物流或FF排水量。建立了一个动态模型，模拟了根系储水、根系吸水和排水到矿质土壤的过程。四参数模型采用逐步程序进行校准。对收集到的数据的分析表明，沉积平原中FF含水量通常低于其他生态系统，而由于FF质量高，FF蓄水量最高。每单位EF厚度的平均存储容量为1.23 mm cm（-1）。敏感性分析和模型参数的校准突出了存储容量作为FF水动力学的最敏感参数的相关性。对于验证期，有一个很好的协议之间的预测和测量FF储水量，特别是预测总排水量从森林地面和测量凋落物流量。模型预测表明，在验证期间（190天）从FF的水吸收不同的生态系统之间，从15%到约28%的参考蒸腾。这似乎与每个生态系统中FF中细根的比例和水的可用性有关。另一方面，总排水量的矿质土壤是非常相似的生态系统之间，除了沉积平原，总排水量是最低的，约87%的传入穿透雨。(C)2000 Elsevier Science B. V.保留所有权利。
A common feature in the undisturbed forest ecosystems in the Middle Caqueta (Colombian Amazonia) is the presence of a thick litter layer with abundant fine roots over mineral soils which are highly weathered and very low in available nutrients. In these situations, the litter layer or the forest Boor (FF) may play an important role in the forest water balance, controlling water fluxes and nutrient cycling. We investigated the forest floor water dynamics in four representative forest ecosystems in the Middle Caqueta, Colombian Amazonia (tertiary sedimentary plain, high terrace, low terrace and the rarely inundated flood plain). Meteorological conditions were measured on hourly basis, FF water storage capacity, TDR water content in the FF and litterflow or FF drainage were measured daily over a two year period. A dynamic model was developed to simulate FF water storage, root water uptake and drainage to the mineral soil. The four-parameter model was calibrated applying a step-wise procedure. Analysis of collected data showed that FF water content was generally lower in the sedimentary plain than in the other ecosystems, whereas FF water storage was the highest due to a high FF mass. The average storage capacity per unit EF thickness was 1.23 mm cm(-1). The sensitivity analysis and calibration of model parameters highlighted the relevance of storage capacity as the most sensitive parameter for the FF water dynamics. For the validation period, there is a good agreement between predicted and measured FF water storage and especially between predicted total drainage from the forest floor and measured litterflow. Model predictions indicate that water uptake from the FF's during the validation period (190 days) differed between ecosystems, ranging from 15 to about 28% of the reference transpiration. This seems to be related to the fraction of fine roots in the FF in each ecosystem and to the water availability. On the other hand, total drainage to the mineral soil was very similar among ecosystems, except for the sedimentary plain, where total drainage was the lowest with about 87% of incoming throughfall. (C) 2000 Elsevier Science B.V. All rights reserved.