Study on Response of Physical Phenomena to Wetland Ecosystem in Large River Mouth

1)对我国7个县的河口滩涂进行了近危种类招潮蟹的生境分布调查。利用神经网络分析方法，研究了底质性质与栖息密度之间的关系。2）对吉野河口的水质和浮游动物进行了观测，为验证数值模拟积累了基础数据。同时，改进了二维河床变化模拟程序和准三维水流模拟程序，并对程序的精度进行了检验。3）在植被调查的基础上，编制了详细的植被网格图。提出了两种预测植物群落分布的方法。4）1999 - 2000年对吉野河口5个湿地进行了野外观测，并对5个湿地的生境特征进行了分析。对该地区的分布进行了调查，并建立了分布型预测模型。对一种常见的大眼沙鼠（Ocypodidae Macrophthalmus）的有机质同化功能进行了定量研究，并对其中一种湿地生态系统的生态功能进行了评价。5）提出了利用主成分分析（PCA）方法获得的特征函数的新的实用方法。它们可以成功地提取出泥沙运动的时间周期性和空间路径，这对于理解地形变化具有重要意义。

1) Field survey of the habitat distribution of Genus Uca that is classified "Near Threatened species" were carried out on river-mouth flats in seven prefectures. The relationship between bed material properties and inhabiting density was examined by using the neural network analysis.2) To accumulate the basic data for verifying the numerical simulation, water qualities and zooplankton were observed in the Yoshino river mouth. To investigate the response of physical phenomena to wetland ecosystems, at the same time, 2D river-bed variation program and quasi-3D flow simulation program were improved and examined their accuracy.3) A detailed meshed vegetation map is presented based on the results of a full vegetation survey. Two methods to predict plant community distribution were proposed. One is a method using the preference curve developed the concept of PHABSIM (Physical Habitat Simulation System) and the other is the neural network analysis.4) Field observations were carried out in five wetlands in the Yoshino river estuary during 1999 and 2000. The distribution of Ocypodidae was investigated and a distribution pattern prediction model was developed. The assimilation function of organic matter by a common Ocypodidae Macrophthalmus japonicus was examined quantitatively to evaluate one of the wetland ecosystems worth.5) New practical methods to utilize the eigen functions obtained by Principal Component Analysis (PCA) were proposed. They can be succeeded to extract the temporal periodicity and the spatial path of sand movement, which are important for understanding the topography change.