Ecological-water requirement of vegetation and its driving factors in karst peek-cluster area

A suitable ecological-water requirement of vegetation model was developed based on field observations in the karst peak-cluster depression area in Tiandong County of Guangxi Province. The ecological-water requirement and ecological water deficiency of vegetation in different seasons were estimated,and the main driving factors were analyzed. The results showed that the greatest ecological-water requirement of 4 dominant vegetation was in August,and the least was in January.The ecological-water requirement of Miscanthus floridulus is the greatest; the monthly average maximum,optimal,and minimum water requirements for this species were 36.85 mm,25.80 mm,and 23.95 mm,respectively. The ecological-water requirement of Cipadessa cinerascens is the least; the average maximum,optimal,and minimum water requirements for this species were 23.99 mm,16.80 mm,and 15.60 mm,respectively. The pattern of ecological-water deficiency is the same with the ecological-water requirement. The ecological-water requirement of vegetation has a significant positive correlation with vegetation coverage,leaf area index,air temperature,and soil bulk density; however,there is a significant negativecorrelation between ecological-water requirement and field water holding capacity. Vegetation coverage,soil bulk density,soil moisture content,and potential evapotranspiration are the main driving factors affecting the ecological-water requirement of vegetation.