Estimation of bark water storage capacity of broad- and needle-leaved trees planted in a semi-arid climate zone

In forest ecosystems, measurement of bark water storage capacity (BWSC) is required for determining the amount of rainfall interception and understanding throughfall and stemflow processes. We compared the bark roughness coefficient (BRC) and BWSC of even-aged, widely-planted, broad-leaved and needle-leaved species in the Chitgar Forest Park, near Tehran, Iran. Bark samples (n = 10 per species) were extracted from three needleleaved species (Cupressus arizonica, Thuja orientalis, and Pinus eldarica) and two broad-leaved species (Acer velutinum and Robinia pseudoacacia). The highest and lowest BWSC was found to be for A. velutinum and P. eldarica trees, respectively (0.63 vs. 0.32 g cm-3). Among the studied species, R. pseudoacacia had the highest BRC (0.69), and the lowest was found to be for A. velutinum species (0.03). The whole tree bole BWSC ranged from 156.8 L for P. eldarica to 14.6 L for A. velutinum. The results suggested that A. velutinum may provide more stemflow to the forest floor due to its small size, low BRC and subsequent low whole tree bole BWSC. These findings significantly contribute to our understanding of rainfall partitioning dynamics and ecohydrological processes associated with stemflow from trees. This improved understanding will help managers in selecting tree hydrologic characteristics that align with their objectives in forestry treatments, afforestation plans and establishment of vegetation in urban park settings within drylands.