Changes in plant debris and carbon stocks across a subalpine forest successional series

Zhihui Wang,Wanqin Yang,Yurui Jiang,Fei Li,Lianjun Zhao,Jianfeng Hou,Xuqing Li,Bingqian Zheng,Yuyue Deng,Yi Bai

doi:10.1186/s40663-021-00320-0

Abstract

BackgroundAs a structurally and functionally important component in forest ecosystems, plant debris plays a crucial role in the global carbon cycle. Although it is well known that plant debris stocks vary greatly with tree species composition, forest type, forest origin, and stand age, simultaneous investigation on the changes in woody and non-woody debris biomass and their carbon stock with forest succession has not been reported. Therefore, woody and non-woody debris and carbon stocks were investigated across a subalpine forest successional gradient in Wanglang National Nature Reserve on the eastern Qinghai-Tibet Plateau.ResultsPlant debris ranged from 25.19 to 82.89 Mg∙ha− 1 and showed a global increasing tendency across the subalpine forest successional series except for decreasing at the S4 successional stage. Accordingly, the ratios of woody to non-woody debris stocks ranged from 26.58 to 208.89, and the highest and lowest ratios of woody to non-woody debris stocks were respectively observed in mid-successional coniferous forest and shrub forest, implying that woody debris dominates the plant debris. In particular, the ratios of coarse to fine woody debris stocks varied greatly with the successional stage, and the highest and lowest ratios were found in later and earlier successional subalpine forests, respectively. Furthermore, the woody debris stock varied greatly with diameter size, and larger diameter woody debris dominated the plant debris. Correspondingly, the carbon stock of plant debris ranged from 10.30 to 38.87 Mg∙ha− 1 across the successional series, and the highest and lowest values were observed in the mid-coniferous stage and shrub forest stage, respectively. Most importantly, the carbon stored in coarse woody debris in later successional forests was four times higher than in earlier successional forests.ConclusionsThe stock and role of woody debris, particularly coarse woody debris, varied greatly with the forest successional stage and dominated the carbon cycle in the subalpine forest ecosystem. Thus, preserving coarse woody debris is a critical strategy for sustainable forest management.

Highlights

Plant debris consists of woody debris (WD) and nonwoody debris (NWD), both of which play crucial roles in nutrient cycling and biodiversity conservation and in the global carbon cycle (Pan et al 2011; Zhu et al 2017)
Plant debris stock across the successional series Plant debris stock ranged from 25.19 to 82.89 Mg∙ha− 1 across the subalpine forest successional series, and the highest and lowest stocks of plant debris were observed in the later successional stage (S5) and earlier forest stage (S1), respectively (Table 1)
When all plant debris components were considered together, the stocks of plant debris represented a total tendency of increasing from the S1 to S6 stands except for the sudden decrease observed in S4 medium-aged earlier coniferous forest

Summary

Introduction

Plant debris consists of woody debris (WD) and nonwoody debris (NWD), both of which play crucial roles in nutrient cycling and biodiversity conservation and in the global carbon cycle (Pan et al 2011; Zhu et al 2017). Thereby, an investigation of the changes in plant debris stock characteristics with tree species composition determined by forest type is crucial to understand the process and function of forest ecosystems. It is well known that plant debris stocks vary greatly with tree species composition, forest type, forest origin, and stand age, simultaneous investigation on the changes in woody and non-woody debris biomass and their carbon stock with forest succession has not been reported. The ratios of coarse to fine woody debris stocks varied greatly with the successional stage, and the highest and lowest ratios were found in later and earlier successional subalpine forests, respectively. The carbon stock of plant debris ranged from 10.30 to 38.87 Mg∙ha− 1 across the successional series, and the highest and lowest values were observed in the mid-coniferous stage and shrub forest stage, respectively. The carbon stored in coarse woody debris in later successional forests was four times higher than in earlier successional forests

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Discussion

Conclusion