Exploratory quantification of 3D spatial competition in ecotone of trees and bamboos using terrestrial laser scanner

•TLS was effective to scan point cloud and quantify 3D spatial competition between trees and bamboos.•Mechanical damage, shading effect and group-synergetic pressure were considered in designing CIs.•Survival Index was calculated combining Survival Intersection Angle Index and Crown Distance Index.•Minimum final SI was caused by group-synergetic pressure exerted by competitive bamboos around.