崩塌地次級演替初期階段近地表水分與環境因子之關係

Relationships Between Near-Surface Soil Moisture and Environmental Features in the Early Stage of Secondary Succession after a Landslide

杜欣庭(Hsin-Ting Tu) ； 梁偉立(Wei-Li Liang)

《台灣林業科學》 36卷1期 (2021/03) Pp. 35-49

https://doi.org/10.7075/TJFS.202103_36(1).0003

摘要

崩塌是臺灣常見的自然擾動，常造成坡地水文環境的改變，並成為坡地後續植生發展或生態系恢復的潛在影響因子。本研究於林試所福山研究中心一處崩塌後3年的源頭集水區，調查地形、土壤、植生與近地表含水率的空間分布，以瞭解在次級演替初期時，坡地水土環境因子空間分布的相關性，以及控制近地表含水率的主要因子為何。調查結果顯示，在崩塌干擾後，坡地上半部擾動程度低（低干擾區），主要擾動區域位於坡地下半部（高干擾區），並發現有地表湧水的存在。相較於低干擾區，崩塌後的高干擾區有較低的土壤孔隙率及飽和水力傳導度，同時有較少的植生留存，近地表含水率的平均值也較低。其中，地表湧水處為低孔隙率和低飽和水力傳導度的區域，但因有水分的湧出而長期維持濕潤。比較近地表含水率與環境因子的空間分布可發現，全樣區範圍之近地表含水率與土壤孔隙率具顯著正相關；低干擾區之近地表含水率則分別與土壤孔隙率、飽和水力傳導度具顯著正、負相關；高干擾區之近地表含水率與環境因子間的空間分布尚無顯著的相關性。根據相關性的差異可得知，崩塌後3年的演替初期，擾動程度大的區域，其近地表含水率與環境因子間的連結尚未重建，進而限制崩塌後的植生恢復。

關鍵字

崩塌地 ； 次級演替 ； 土壤含水率 ； 土壤物理性質 ； 植生恢復

並列摘要

Landslides are common natural disturbances in Taiwan, and they usually change the hydrological conditions on hillslopes and influence subsequent vegetation development or ecosystem restoration. To explore the main environmental features controlling the near-surface soil water content after a landslide, this study investigated spatial distributions of topographic and edaphic features, vegetation, and near-surface soil water content. Investigations were conducted in a headwater catchment at the Fushan Research Center of the Taiwan Forestry Research Institute, northern Taiwan in the third year after a landslide had occurred in the headwater. The headwater was partitioned into 2 areas based on disturbance levels. A low-disturbed area was located in the upslope area, and a highly-disturbed area was located in the downslope area where springs were found. Compared to the low-disturbed area, the highly-disturbed area had lower soil porosity, lower saturated hydraulic conductivity, less remaining vegetation, and a lower mean near-surface soil water content. At locations near the springs, both soil porosity and saturated hydraulic conductivity were low, but the near-surface soil water content was consistently high due to being supplied by the springs. As to correlations between spatial distributions of the near-surface soil water content and environmental features, the soil water content was significantly correlated with soil porosity for the entire site. In the low-disturbed area, soil water content was positively correlated with soil porosity and negatively correlated with saturated hydraulic conductivity. In the highly-disturbed area, no significant spatial correlations were found between soil water content and environmental features. The results indicated that connections between the near-surface soil water content and environmental features had not been reestablished in the highly-disturbed area in the initial stage of secondary succession. This could limit subsequent vegetative development after a landslide.

並列關鍵字

landslide ； secondary succession ； soil moisture ； soil physical property ； vegetation recovery