以判別分析探討香山溼地台灣招潮蟹棲地特性

Abstract

台灣招潮蟹為一瀕臨絕種之台灣特有種，香山溼地的三姓公溪與 海山罟一帶為目前僅存之少數台灣招潮蟹棲地。本研究以網格式採 樣，比較該區域不同類型棲地之土壤粒徑組成、土壤飽和液電導度及 酸鹼度、土壤氧化還原電位、土壤溶液重金屬含量、土壤有機碳、土 壤全氮、土壤假比重、土壤飽和孔隙率、現地含水量、現地假比重、 土壤應力、植物覆蓋面積百分比、浸沒時間百分比等環境因子，並以 判別分析區別台灣招潮蟹可能棲地。 此區域台灣招潮蟹棲地主要分佈在年平均浸沒時間5.1%的高潮 位地帶。地表植物覆蓋度平均值為1.4%，近乎為裸露灘地。土壤質 地為坋質粘土，平均粘粒含量為40.4%，平均砂粒含量15.8%。判別 結果顯示裸露灘地面積10.9 公頃、草本植物區2.9 公頃、紅樹林區 18.1 公頃、台灣招潮蟹棲地8.1 公頃。

Uca formosensis is an endemic fiddler crab in Taiwan. Hsiang-Shan Wetland is one of the few habitats left for Uca formosensis. Construction of wastewater treatment station in the wetland between Sanhsingkung river and Dachuang river may deteriorate habitats for Uca formosensis in that area. Soil sampling were taken with 100 meter intervals by grid, and particle size distribution, electrical conductivity and pH of saturated soil water, oxidation-reduction potential, heavy metal concentration, total organic content, total nitrogen, bulk density, porosity, in-situ bulk density and water content were measured in the laboratory. Soil penetration were measured in situ. Percentage of vegetation coverage were measured by aerial photograph. Average submerged time were measured by in-situ investigation and tidal records. Four types of habitats were classified by discriminant analysis. We found Uca formosensis live in the upper intertidal zone with a mean submerged time of 5.1%. Vegetation coverage percentage on the ground is less than 1.4%. Soil contains 40.4% of clay and 15.8% of sand. Penetration force is 41.6N/cm2. Discriminant analysis shows that there are 10.9 ha., 2.9 ha., 18.1 ha., 8.2 ha. classified for bare area, herbaceous plant area, mangrove area and Uca formosensis habitat, respectively.