Improving riparian greenspace established in river watersheds

Abstract

The purpose of this study was to analyze the propriety of establishing riparian greenspace for watersheds of four major rivers in South Korea and suggest strategies for improving the analyzed problems. Growth environments, vegetation structures, planting techniques, and tree growth and management conditions were analyzed targeting 45 sites. Soils at the sites had organic matter of 1.3 % and cation exchange capacity of 4.4 cmol⁺/kg, which are poor conditions for tree growth. A tree diameter at breast height of <7 cm accounted for 77 % of all trees planted, and mean tree cover was only 28 % due to planting of mainly small trees. Planting techniques were represented by single-layered planting (84 %) consisting of a single species or a few species in similar size. Approximately 11 % of all planted trees withered, and many trees had poor growth. The growth ratios for shoot and leaf length in planted trees compared with normally growing trees were 57 and 77 %, respectively. Oppression by invasion of herbaceous and climbing plants associated with negligent maintenance hindered normal tree growth at some sites. Strategies to improve these problems and promote the function of riparian greenspaces suggest securing a minimum width and connectivity of greenspace, analyzing growth ground prior to planting, improving the soil environment, woodchip mulching on ground surfaces, middle/high density plantings mixed with fast-growing trees, edge planting to protect internal growth environment, and multilayered and grouped ecological planting reflecting natural riparian forest structures.