Role of plant health parameters in understanding spatial heterogeneity of hydraulic conductivity of vegetated soil: A case study of urban green infrastructure monitoring

Abstract

Development of green infrastructure is widely adopted as a key strategy for enhancing socio-ecological benefits in urban areas. Generally, four categories of vegetation exist in urban green infrastructure. Those are (i) vegetated soil under tree shade during entire daylight period, (ii) vegetated soil under tree shade during 3–4 h of daylight period, (iii) vegetated soil under light during entire daylight period and (iv) soil surface covered by mix grass and shredded leaves. Previous studies have shown that presence of vegetation may influence hydraulic conductivity. The main factors those govern such influence are found to be growth of vegetation, which is directly related to photosynthesis and stomatal conductance. Stomatal conductance is the measure of passage of carbon dioxide or water vapor through stomata of leaf. The objective of this study is to investigate role of plant health parameters in understanding spatial heterogeneity of hydraulic conductivity in urban green infrastructure. Field monitoring of mix vegetated soil was conducted for about three months. Plant health is investigated in terms of vegetation growth and stomatal conductance. Stomatal conductance and hydraulic conductivity were measured in 150 locations in selected site once every month. Stomatal conductance was measured using an electronic sensor (leaf porometer). Mini disk infiltrometer was used to measure hydraulic conductivity. Stomatal conductance of mix grass under light for longer duration (around 8 h) was found to be higher than that under light for shorter duration (3–4 h) and shade. Hydraulic conductivity of mix grass cover under shade was found to be relatively low. As compared to stomatal conductance, preferential flow is found to be more dominant in governing the hydraulic conductivity.