Effects of Stand Origin and Near-Natural Restoration on the Stock and Structural Composition of Fallen Trees in Mid-Subtropical Forests

Chunsheng Wu,Liangying Liu,Yuanqiu Liu,Chunjie Shu,Qinglin Li,Xiaodong Li,Qifeng Mo,Xiaohua Wei

doi:10.3390/f6124380

Abstract

Fallen trees comprise an important part of forest ecosystems and serve a central role in maintaining the biodiversity and tree regeneration of forests. However, the effects of stand origin and near-natural restoration on the biomass and carbon stock of fallen trees remain unclear. Based on 60 sampling plots of field surveys of mid-subtropical forests in Jiangxi Province, we investigated the stock and structural composition of fallen trees in artificial coniferous forests (Acf), natural coniferous forests (Ncf) (e.g., different stand origins) and natural evergreen broadleaf forests (Nebf) (e.g., near-natural restoration). The following results were obtained: (1) the largest biomass and carbon stocks of fallen trees among three forest types (Nebf, Ncf and Acf) were measured for Nebf; (2) the fallen tree biomass and carbon stock in natural Cunninghamia lanceolata forest (Nclf) were significantly larger than that in artificial Cunninghamia lanceolata forest (Aclf), and the fallen tree biomass and carbon stock in natural Pinus massoniana forest (Npf) were also significantly larger than those in artificial Pinus massoniana forest (Apf); (3) the diameter class allocation in natural forests was more uniform than that in artificial forests; (4) the biomass of fallen trees with mild decay was not significantly different among forest types within stand origin or among the stand origin within forest types; however, the biomass of fallen trees with moderate and heavy decay significantly differed among stand origin (Aclf vs. Nclf, Apf vs. Npf), but was not significant among the forest types (Aclf vs. Apf, Nclf vs. Apf) within a stand origin. Our results suggested that the large biomass and carbon stock of fallen trees in Nebf may serve a significant role in mitigating global warming and carbon cycles in mid-subtropical forests. Therefore, stand origin and near-natural restoration exert significant effects on the carbon stock and structural composition of fallen trees in mid-subtropical forests.

Highlights

Fallen trees are an important part of forests and can be regarded as carbon and nutrient pools, which serve a crucial role in the biogeochemical cycles and global carbon balance in forest ecosystems
The biomass of fallen trees in natural coniferous forests (Ncf) (1.625 ̆ 0.22 t/hm2) was significantly higher than that in artificial coniferous forests (Acf) (0.813 ̆ 0.25 t/hm2), and Acf yielded a significant reduction compared with the natural evergreen broadleaf forests (Nebf) climax forests (11.061 ̆ 1.15 t/hm2) (Figure 1)
Our results indicated that the biomass of fallen trees in Nebf was significantly higher than the biomass of fallen trees in Acf and Ncf

Summary

Introduction

Fallen trees are an important part of forests and can be regarded as carbon and nutrient pools, which serve a crucial role in the biogeochemical cycles and global carbon balance in forest ecosystems. The carbon storage of fallen trees in global forests is (2.0–16.0) ˆ 1010 mg, which accounts for 1.75%–13.96% of the carbon stock in the global forest ecosystem (114.6 ˆ 1011 mg) [6]. In order to make a complete estimation of carbon storage in forest ecosystem, the biomass of fallen trees must be considered [7]. Investigation of the direct and indirect effects of external factors (disturbance, competition, forest type and stand age) on the biomass, decomposition and structure of fallen trees is relatively important for the carbon storage and functional balance in forest ecosystems

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Discussion

Conclusion