Study on evolution of hydrobiogeochemistry with forest succession in humid temperate region

湿温带森林演替的水生生物地球化学演化研究

基本信息

批准号：
10660146
负责人：
OHTE Nobuhito
金额：
$ 2.18万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

In order to examine the various impacts of the forest growth on the acid buffering processes, hydrochemical observations were carried out in three different temperate catchments, each shares the same granitic bedrock , but having a forest different in growth conditions and soil depth. Hydrological processes in those watersheds were classified as; (1) the throughfall process, (2) soil infiltration process, (surface and subsurface soil layer infiltration sub-process, and the saturated groundwater transfer sub-process) and (3) the stream runoff process. The spatial distribution of pH, proton fluxes, and the changes of the proton producing and consuming processes were clarified. Specifically observed as changes accompanied by the vegetation growth were; (1) the decomposition of organic matters generated protons and (2) in addition to the chemical weathering , the cation exchange process started to consume protons in surface soil layer. (3) as a result, the proton production was relatively … More greater than consumption the surface soil layer, and some of the protons left unconsumed were transferred down to the subsurface soil layer and consumed. Specifically observed changes relating to soil depth were ; (1) pCOィイD22ィエD2 level at the groundwater is increased, as the soil layer is thicker. (2) As a result, pH after degassing is increased as the soil depth increased. Second, to quantify the impacts of forest vegetation on the acid buffering processes, hydrochemical observation data for two separate years were used to calculate the proton budgets in three small catchments, each consisting of the same granitic bedrock, but differing in vegetation development conditions. The increase in biological activity in the forested catchments, increased the net proton production by mineralization of organic matters and N transformation. In the forested catchments, the increase in transpiration reduced stream runoff. As a result, proton production by the dissociation of COィイD22ィエD2 decreased. When the estimated value for the cation uptake by vegetation was included in the proton budget, forest development increased the sum of these net proton productions by 2.3 to 4.0 times that of bare catchments. However, more than 96% of these proton productions were consumed by weathering and cation exchange within the catchments. It became apparent that the sum of these net proton productions by atmospheric input, N transformation, assimilation of cations, and dissociation of COィイD22ィエD2 is strongly affected by the amount of annual precipitation and annual runoff. The variance of proton production due to the fluctuation of annual precipitation almost equals the range of the increase in proton production by forest growth. Less

为了研究森林生长对酸缓冲过程的各种影响，在三个不同的温带流域进行了水化学观测，每个流域都有相同的花岗岩基岩，但森林的生长条件和土壤水文过程不同。这些流域被分类为：（1）穿流过程，（2）土壤入渗过程，（地表和地下土壤层入渗子过程，以及饱和地下水输送子过程）和（3）河流明确了 pH 值、质子通量的空间分布以及质子产生和消耗过程的变化，具体观察为：（1）有机物分解产生的质子。除了化学风化之外，阳离子交换过程开始消耗表土层中的质子（3），因此，产生的质子相对大于消耗表土层，并且留下了一些质子。未消耗的物质被转移到地下土壤层并被消耗，观察到的与土壤深度相关的变化是：（1）随着土壤层变厚，pCO22D2 水平增加。其次，为了量化森林植被对酸缓冲过程的影响，使用了两个不同年份的水化学观测数据来计算三个小流域的质子预算，每个流域包括相同的花岗岩基岩，但植被发育条件不同。森林流域生物活动的增加，通过有机物矿化和氮转化增加了净质子产量。在森林流域中，蒸腾作用的增加减少了溪流径流。结果，COiiD22diéD2 解离产生的质子产量减少。当植被吸收的阳离子的估计值包含在质子预算中时，森林开发增加了这些净质子产量的总和。是裸流域的 2.3 至 4.0 倍，然而，超过 96% 的质子产量被流域内的风化和阳离子交换所消耗，很明显，这些净质子产量的总和是由大气输入、氮转化、同化所消耗的。 COID22D2 的阳离子和解离受到年降水量和年径流的强烈影响，质子产量的变化几乎由于年降水量的波动而变化。等于森林生长导致的质子产量增加的幅度。