Re-estimating the changes and ranges of forest biomass carbon in China during the past 40 years

Abstract

Background: In recent decades the future of global forests has been a matter of increasing concern, particularly in relation to the threat of forest ecosystem responses under potential climate change. To the future predictions of these responses, the current forest biomass carbon storage (FCS) should first be clarified as much as possible, especially at national scales. However, few studies have introduced how to verify an FCS estimate by delimiting the reasonable ranges. This paper addresses an estimation of national FCS and its verification using two-step process to narrow the uncertainty. Our study focuses on a methodology for reducing the uncertainty resulted by converting from growing stock volume to above-and below-ground biomass (AB biomass), so as to eliminate the significant bias in national scale estimations. Methods: We recommend splitting the estimation into two parts, one part for stem and the other part for AB biomass to preclude possible significant bias. Our method estimates the stem biomass from volume and wood density (WD), and converts the AB biomass from stem biomass by using allometric relationships. Results: Based on the presented two-step process, the estimation of China's FCS is performed as an example to explicate how to infer the ranges of national FCS. The experimental results demonstrate a national FCS estimation within the reasonable ranges (relative errors: + 4.46% and − 4.44%), e.g., 5.6-6.1 PgC for China's forest ecosystem at the beginning of the 2010s. These ranges are less than 0.52 PgC for confirming each FCS estimate of different periods during the last 40 years. In addition, our results suggest the upper-limits by specifying a highly impractical value of WD (0.7 t•m − 3 ) on the national scale. As a control reference, this value decides what estimate is impossible to achieve for the FCS estimates.Conclusions: Presented methodological analysis highlights the possibility to determine a range that the true value could be located in. The two-step process will help to verify national FCS and also to reduce uncertainty in related studies. While the true value of national FCS is immeasurable, our work should motivate future studies that explore new estimations to approach the true value by narrowing the uncertainty in FCS estimations on national and global scales.

Reconciliation of research on forest carbon sequestration and water conservation

“…On the ecosystem service of forest carbon sequestration, research to date well supports the scaling up of forest carbon stock and fluxes from stand level to regional and global scales (Law et al 2004;Pan et al 2011;Zhou et al 2019).…”

“…Traditional estimations of forest carbon stock and its changes include harvesting and modeling methods. Direct harvesting of trees involves measurements of different tree components, such as trunk, leaves, branches, and roots (Zhou et al 2019;Sun and Liu 2020). Soils were also sampled to provide full accounting of forest ecosystem carbon stock (Tang et al 2018).…”

“…Many factors affect the density and partitioning of carbon in forest stands. Continentally and globally, climate appears to the most important factor shaping the spatial patterns of forest carbon stocks (Pan et al 2011;Zhou et al 2019), and locally and regionally, the density and partitioning of forest carbon varies with tree species, forest structure and types, stand development, management, and soil conditions (Giardina and Ryan 2000;Law et al 2004;Sun et al 2004;Li et al 2019). Marked differences can been found in forest carbon in relation to forest types, development, and site conditions regionally (Law et al 2004) and at landscape-scale (Li et al 2019), and between natural and planted forests (Yu et al 2019).…”

New Forest Aboveground Biomass Maps of China Integrating Multiple Datasets

“…The forest AGB stock in China was 7.73 Pg C for the WT estimates and 8.13 Pg C for the RF estimates. Unlike the previous studies that used field measurements from multiple sources with variable quality over different periods, our field measurements were acquired over the same period using a unified measurement protocol, minimizing inconsistency and measurement errors [7,85]. Moreover, the WT method used here accounted for both the performance against field measurement and error dependences in the participating AGB datasets.…”

Dynamics of Carbon Storage and Its Drivers in Guangdong Province from 1979 to 2012

“…Biomass expansion factor method can accurately estimate forest biomass. In summary of previous studies [25][26][27][28][29][30][31], we selected the commonly recognized biomass expansion factor method in this work.…”