香山濕地台灣招潮蟹棲地類型底質特性研究

Research of Habitat Type and Sediment Properties of Uca formosensis in Hsiang-Shan Wetland

林世偉(Shih-Wei Lin) ； 廖少威(Shao-Wei Liao) ； 張文亮(Wen-Liang Chang)

《農業工程學報》 52卷4期 (2006/12) Pp. 1-14

摘要

台灣招潮蟹為一瀕臨絕種之台灣特有種招潮蟹，而香山溼地三姓公溪與海山罟一帶為目前僅存少數台灣招潮蟹棲地。本研究以台灣招潮蟹棲地底質特性等環境因子，配合現地觀察選定四種棲地地貌類型，以判別分析方法歸類台灣招潮蟹可能棲地。經由典型判別分析的結果，三個判別函數解釋了香山濕地底質的變異性，建構出底質特性對於不同地貌棲地分佈之函數，判別能力分別為49.5%、32.8%及17.7%，累積判別能力高達100%。以因子結構係數來說明整個資料結構的變異，此三個判別函數主要是「土壤質地影響因子」、「潮汐影響因子」、「營養源影響因子」、「氧化還原影響因子」等所組成。對於台灣招潮蟹喜好的底質棲息特性；土壤質地為平均砂粒含量34.05%、紛粒含量29.72%、粕粒含量32.35%，屬粕質壤土特性。棲地年平均浸沒時問百分比為8%，顯示其習性喜好棲息於較高潮位灘地。棲地植物覆蓋度為2.20%，顯示其棲地植物量相當少，喜好近乎裸露之灘地。在巢穴位置的選擇上，土壤應力過高的區域會增加台灣招潮蟹挖洞的困難性。在本研究其20公分土壤應力值為51.11N/平方公分。透過對底質資料的監測，結合所建立的判別函數模式即可明確瞭解地貌可能演替趨勢，再透過復育以控制改變此些影響參數，進而控制棲地地貌類型的改變，以復育及保護瀕臨絕種的台灣招潮蟹。

關鍵字

台灣招潮蟹 ； 底質特性 ； 典型判別分析 ； 香山濕地

並列摘要

Uca formosensis is an endemic fiddler crab in Taiwan. And Hsiang-Shan wetland is one of the few habitats left for U. formosensis. This work investigated soil samples collected from Hsiang-Shan wetland, Taiwan to identify the favorite habitats for U. formosensis. Canonical discriminant analysis is applied to identify an existing habitat type scheme by investigating the physical-chemical properties of sediment in Hsiang-Shan wetland. We recognized habitat types by field visual reconnaissance and indicated that the habitat could be classified into four regions-bare area, mangrove area, U. formosensis living habitat, and herbaceous plant area. There are three constructed discriminant functions (CDFs) showed markedly contributions to most of the discriminant variables, and their recognition capacities were 49.5%, 32.8% and 17.7%, respectively. The result shows that the most important latent factors in Hsiang-Shan wetland are the soil texture impact factor, tidal impact factor, the nutrient impact factor, and the oxidation-reduction impact factor. The most favorate sediment properties for U. formosensis in soil texture are sand (34.05%), silt (29.72%), and clay (32.35%), namely clay loam. In addition, we found that U. formosensis liked to live in the upper intertidal zone with a mean yearly submerged time of 8%. According to a very low vegetation coverage percentage on the ground (less than 2.20%), we conclude that it preferred living in coverless areas. Regarding the nest choosing, higher soil stress will enhance the difficulty for digging. In this study, we found that soil penetration force in 20-cm depth is 51.11N/cm^2. Integrating these CDFs with sediment monitoring data can control habitat evolution, and can feasibly conserve a suitable habitat for U. formosensis by processing these unstable predictor variables. The methodology and results provide some useful information on the conservation of habitats for endemic U. formosensis in Hsiang-Shan. It may also be applicable to other wetlands with similar properties that are experiencing similar environmental issues.

並列關鍵字

Uca formosensis ； Sediment properties ； Canonical discriminant analysis ； Hsiang-Shan wetland