Detecting the Competition between Moso Bamboos and Broad-Leaved Trees in Mixed Forests Using a Terrestrial Laser Scanner

Meichun Zhan,Shaohui Fan,Yingjie Yan,Mingpeng Xia,Fengying Guan

doi:10.3390/f9090520

Abstract

The growth of individual trees in a forest is affected by many factors, a crucial one being the intensity of competition among trees, because it affects the spatial structure of the forest and is in turn influenced by silvicultural practices. In a mixed forest in particular, the growth of trees is affected by multiple interactions. To analyse the competition between moso bamboo (Phyllostachys pubescens (Pradelle) Mazel ex J.Houz.) and broad-leaved trees in a mixed forest, data were extracted by sampling six spots within such a forest using terrestrial laser scanning (TLS). The convex hull algorithm was used for calculating the overlap volume between the crowns of the broad-leaved trees and the bamboo canopy. Bamboos growing at least 3 m away from any of the broad-leaved trees were the most numerous and the diameter at breast height (DBH) is larger than those growing closer than that, which suggests that broad-leaved trees suppressed the growth of bamboo if they are closer but promote it beyond 3 m up to a point at which the distance is too great for any such effect. The modified Hegyi’s competition index was constructed based on the canopy factor, which may better describe the competitive interaction among the trees and bamboos. Using TLS can enhance our understanding of the competition among trees in mixed forests and help in planning the spatial structure of such forests in general and provide a benchmark for choosing planting distances in particular.

Highlights

Moso bamboo (Phyllostachys pubescens (Pradelle) Mazel ex J.Houz.) is extensively distributed in south-eastern and southern Asia, important to the global carbon cycle and water conservation, and an important forest species because it grows fast and has a short life cycle
Traditional ways of managing forests of pure bamboo have resulted in the decline of the sites of such forests, lower soil fertility, and increasing damage by pests and diseases, whereas many recent studies have shown that mixed forests comprising bamboo and broad-leaved trees are conducive to maintaining ecosystem balance, improving stand structure, and increasing soil fertility [1]
Using multi-station scanning to extract the original point-cloud data in the sample plots and splicing the data for each sample gave an overall recognition rate for trees of 97.71%, while the single station recognition rate is 82.56% (Table 4). These results show that the values of the diameter at breast height (DBH) as estimated by terrestrial laser scanning (TLS) were similar to those arrived at through artificial measurement

Summary

Introduction

Moso bamboo (Phyllostachys pubescens (Pradelle) Mazel ex J.Houz.) is extensively distributed in south-eastern and southern Asia, important to the global carbon cycle and water conservation, and an important forest species because it grows fast and has a short life cycle. Improving the operating efficiency and economic returns from bamboo forests is, important, which among other things, requires suitable methods to examine and monitor bamboos growing in forests—methods that are efficient, feasible, and accurate. Traditional ways of managing forests of pure bamboo have resulted in the decline of the sites of such forests, lower soil fertility, and increasing damage by pests and diseases, whereas many recent studies have shown that mixed forests comprising bamboo and broad-leaved trees are conducive to maintaining ecosystem balance, improving stand structure, and increasing soil fertility [1]. Studying the relationship between broad-leaved trees and bamboo in such mixed forests will help to manage them efficiently and to obtain higher economic returns.

Methods

Results

Discussion

Conclusion