ABSTRACT
Plant transpiration has been shown to have significant effects on soil hydrological changes in terms of soil moisture and matric suction in flat vegetated soil under controlled-atmosphere conditions (Chapter 2). This chapter aims to extend the discussion of the effects of plant community (e.g., mixed tree?grass planting) and vegetation management (e.g., tree spacing) on plant growth, soil infiltrability and transpiration-induced changes in slope hydrology under natural field conditions. Assuming that the behaviour of unsaturated soil is governed by two independent stress-state variables (net stress and matric suction; Fredlund and Rahardjo, 1993; Ng and Menzies, 2007), the effects of transpiration-induced changes in suction, soil stress and slope movement are investigated by interpreting three well-documented field case studies. The three field cases include (1) a compacted sandy ground at HKUST Eco-Park; (2) a cut slope in expansive clay in Zaoyang, China, and (3) a natural saprolitic hillslope in Hong Kong.
