Allocation pattern and accumulation potential of carbon stock in natural spruce forests in northwest China

Jun-Wei Yue; Jin-Hong Guan; Lei Deng; Jian-Guo Zhang; Guoqing Li; Sheng Du

doi:10.7717/peerj.4859

Allocation pattern and accumulation potential of carbon stock in natural spruce forests in northwest China

PeerJ. 2018 May 25:6:e4859. doi: 10.7717/peerj.4859. eCollection 2018.

Authors

Jun-Wei Yue^{1

2

3}, Jin-Hong Guan², Lei Deng⁴, Jian-Guo Zhang⁵, Guoqing Li^{1

2}, Sheng Du^{1

2}

Affiliations

¹ State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi, People's Republic of China.
² Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi, People's Republic of China.
³ University of Chinese Academy of Sciences, Beijing, People's Republic of China.
⁴ Academy of Agriculture and Forestry Sciences, Qinghai University, Xining, Qinghai, People's Republic of China.
⁵ Upper and Middle Yellow River Bureau, Yellow River Conservancy Commission of the Ministry of Water Resources, Xi'an, Shaanxi, People's Republic of China.

Abstract

Background: The spruce forests are dominant communities in northwest China, and play a key role in national carbon budgets. However, the patterns of carbon stock distribution and accumulation potential across stand ages are poorly documented.

Methods: We investigated the carbon stocks in biomass and soil in the natural spruce forests in the region by surveys on 39 plots. Biomass of tree components were estimated using allometric equations previously established based on tree height and diameter at breast height, while biomass in understory (shrub and herb) and forest floor were determined by total harvesting method. Fine root biomass was estimated by soil coring technique. Carbon stocks in various biomass components and soil (0-100 cm) were estimated by analyzing the carbon content of each component.

Results: The results showed that carbon stock in these forest ecosystems can be as high as 510.1 t ha^-1, with an average of 449.4 t ha^-1. Carbon stock ranged from 28.1 to 93.9 t ha^-1 and from 0.6 to 8.7 t ha^-1 with stand ages in trees and deadwoods, respectively. The proportion of shrubs, herbs, fine roots, litter and deadwoods ranged from 0.1% to 1% of the total ecosystem carbon, and was age-independent. Fine roots and deadwood which contribute to about 2% of the biomass carbon should be attached considerable weight in the investigation of natural forests. Soil carbon stock did not show a changing trend with stand age, ranging from 254.2 to 420.0 t ha^-1 with an average of 358.7 t ha^-1. The average value of carbon sequestration potential for these forests was estimated as 29.4 t ha^-1, with the lower aged ones being the dominant contributor. The maximum carbon sequestration rate was 2.47 t ha^-1 year^-1 appearing in the growth stage of 37-56 years.

Conclusion: The carbon stock in biomass was the major contributor to the increment of carbon stock in ecosystems. Stand age is not a good predictor of soil carbon stocks and accurate evaluation of the soil carbon dynamics thus requires long-term monitoring in situ. The results not only revealed carbon stock status and dynamics in these natural forests but were helpful to understand the role of Natural Forest Protection project in forest carbon sequestration as well.

Keywords: Carbon sequestration potential; Carbon stock; Spruce forests; Stand age.

Grants and funding

The study was supported by the Strategic Priority Research Project of the Chinese Academy of Sciences (XDA05050202): Current stocks, sequestration rate and potential of forest carbon in the temperate western China. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.