Designing near-natural planting patterns for plantation forests in China

Abstract

Background: China has a long tradition of managing planted forests. Different species of Populus, Eucalyptus, Larix, Cunninghamia and Pinus are planted to satisfy the local demand for wood products and provide ecological services at the same time. Evidence of the greater resilience of natural forests provides the motivation to develop asymmetric planting patterns, which is the focus of this study. We present a new method for designing plantation patterns that follow those observed in natural ecosystems and to maintain some regularity for operational convenience. Methods: Based on the uniform angle index, we analyzed the spatial structure of six natural forests in different regions of China. The uniform angle index describes the degree of spatial uniformity of the n nearest neighbors of a given reference tree. Accordingly, we identified all possible patterns of a neighborhood group within a regular planting pattern and developed a method to optimize planting point arrangements that contain some randomness as well as a minimum degree of regularity. Results: (1) There are 13 types of structural units in a regular planting, including seven random units, five even units and one cluster unit; (2) Five near-natural arrangements are presented with a minimum proportion of 50% of random units. These five arrangements represent a combination of regularity for operational convenience and asymmetry. Conclusions: The new planting patterns developed in this study are expected to increase the asymmetric competition and resilience of these important ecosystems. Some experimental plantings, based on our findings, have already been established, e.g., in Pinus tabulaeformis plantations in Tianshui, Gansu Province, and in a Populus deltoides plantation in Fangshan near Beijing.

Random Trees Are the Cornerstones of Natural Forests

“…However, plantations, especially new artificial forests, did not show the same result. The symmetrical and orderly arrangement of individuals in plantations makes the spatial pattern different from the natural forests [19]. However, we only know the quantity advantage of random trees, but its importance in natural forests is unknown.…”

A simple and effective approach to quantitatively characterize structural complexity

“…Each W i value matches a different pattern of neighbours 40 . For convenience, we named the small pattern formed by the reference tree and its nearest four neighbours the structural unit 50 . Each structural unit is composed of five trees: one reference tree and four nearest neighbours.…”

Clumped or regular? the role of thinning pattern on pine growth and soil water content in dense Aleppo pine post-fire stands

“…However, restoring Aleppo pine forest resilience and overall functioning could be better achieved by treatments that seek to promote structural and functional complexity within the stands, mimicking natural and healthy forests (Boyden et al 2005;Churchill et al 2013), while maintaining similar levels of residual tree growth and productivity. Similarly, it has been suggested that near-natural arrangements of planted trees could increase the resilience of forest stands as compared with regularly spaced stands (Zhang et al 2019). Furthermore, an aggregated pattern of pine thinning creates a mosaic of tree patches and gaps where understory vegetation can thrive, particularly if resprouter species are present in the area, contributing to increase the structural complexity and heterogeneity of the ecosystem, thus providing niches for biodiversity and promoting higher functional diversity of plants.…”