Strategy of fine root expansion of Phyllostachys pubescens population into evergreen broad-leaved forest

Abstract

Aims Roots, particularly fine roots, play an important role in interspecies competition. Our objective was to study the spatial distribution, morphological characteristics and growth rates of fine roots in both bamboo (Phyllostachys pubescens) and broad-leaved trees to better understand the mechanisms of expansion of bamboo into evergreen broad-leaved forest. Methods We continuously sampled P. pubescens forest (PPF), bamboo-broad-leaved mixed forest (BMF) and evergreen broad-leaved forest (EBF) perpendicular to a bamboo-broad-leaved forest interface on Dagang Mountain, Jiangxi Province, China. The live fine root biomass, specific root length (SRL), root length density (RLD), fine root growth and turnover rates were comparatively analyzed by soil core and ingrowth methods. Important findings Fine root biomass of PPF (1 201.60 g·m –2 ) was much larger than that of BMF (601.18 g·m –2 ) and EBF (204.88 g·m –2 ). Vertical stratification of bamboo fine roots in BMF was found to shift from lower to upper soil layers, SRL of bamboo significantly increased by 123.42% and average RLD of bamboo was 210.0% greater than that of broad-leaved trees. In addition, both growth and turnover rates of bamboo fine roots were faster than those of trees. Findings indicated that P. pubescens, with wide, precise, flexible and fast nutrient access and space-occupation abilities, would outcompete trees belowground, resulting in expansion of its population into evergreen broad-leaved forest.