Allocation of forest biomass across broad precipitation gradients in China\u2019s forests

Zhiyang Lie,Douglass F Jacobs,Li Xue

doi:10.1038/s41598-018-28899-5

Zhiyang Lie, Douglass F Jacobs + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-28899-5

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Abstract

Forests act as major sinks for atmospheric CO2. An understanding of the relationship between forest biomass allocation and precipitation gradients is needed to estimate the impacts of changes in precipitation on carbon stores. Biomass patterns depend on tree size or age, making it unclear whether biomass allocation is limited by tree age at regional scales. Using a dataset of ten typical forest types spanning a large age scale, we evaluated forest biomass allocation–precipitation correlations with the aim of testing whether biomass allocation patterns vary systematically in response to altered precipitation. With increasing mean annual precipitation, a significant quadratic increase occurred in ≤30 yr and >60 yr groups in stem biomass, >60 yr group in branch biomass, and >60 yr groups in leaf biomass; and a significant cubic increase occurred in 30–60 yr and all age forest groups in stem biomass, ≤30 yr, 30–60 yr and all age forest groups in branch biomass, ≤30 yr and all age forest groups in leaf biomass, and in each group in root biomass, indicating that organ biomass is strongly limited by precipitation. Thus, forest biomass responds predictably to changes in mean annual precipitation. The results suggest that forest organ biomass–precipitation relationships hold across independent datasets that encompass a broad climatic range and forest age.

Highlights

Over the past several decades, the earth has experienced profound climatic change[1,2], which affects forest growth
A growing number of studies have proposed that annual precipitation governs forest biomass[20], but many forest biomass studies are based on empirical correlations restricted to a single forest type[21]
Many other environmental and climatic factors affect biomass allocation, we focused our analysis on mean annual precipitation (MAP) because of the availability of comprehensive data on this variable

Summary

Introduction

Over the past several decades, the earth has experienced profound climatic change[1,2], which affects forest growth. Some researchers suggested that biomass distribution can be influenced by climate[6,12], whereas Cairns et al.[14] found no relationship between global root biomass and climate Whether these allocation patterns vary systematically across climatic gradients remains unknown, which represents a critical knowledge gap[15,16]. Mean annual precipitation (mm) leaf and root, with precipitation It is often unclear how the relative balance among organ biomass varies across a precipitation gradient. Such information is necessary for fine-tuning or constraining carbon stock estimates by vegetation type and precipitation zone[23] and for improving our understanding of how precipitation affects forest biomass[4]. Despite the importance of these forests for carbon cycling in China, influences of precipitation on biomass allocation among organs in these forests remain unclear

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