Fine Root Biomass and Its Relationship with Aboveground Traits of Larix gmelinii Trees in Northeastern China

Shengwang Meng,Jian Yu,Hua Zhou,Qijing Liu,Quanquan Jia,Guang Zhou

doi:10.3390/f9010035

Abstract

Fine roots play a prominent role in forest carbon flux, nutrient and water acquisition; however, information on fine roots remains scarce due to the limitation of measuring methods. In this study, a nested regression method was used to estimate the biomass and surface area of fine roots of individual Larix gmelinii trees that dominate northernmost China. Aboveground traits including leaf biomass, leaf area, stem volume and aboveground biomass were also investigated. In particular, the relationships between leaves and fine roots, in terms of biomass and area, were examined. The results revealed that allometric models of fine roots, total roots, and leaves consistently fit well with Adj. R2 = 0.92–0.97. The root-shoot ratio at the individual tree level was approximately 0.28. There were robust positive linear correlations between absorption (fine root biomass, fine root surface area) and production (leaf biomass, leaf area) (Adj. R2 = 0.95, p < 0.001). In conclusion, the close coupling between fine roots and leaves presented in this study provides support for the theory of functional equilibrium.

Highlights

Boreal forests play a critical role with respect to their contribution to global carbon dynamics [1].Mid- and high-latitude forests contain approximately 63% of the total carbon pool contained in global forest vegetation, and soils contain more than 66% of the carbon in forest ecosystems [2]
The specific objectives of the present study were to develop allometric models for aboveground and belowground traits regressed against dbh by taking advantage of nested regression, to examine whether aboveground biomass and stem volume are good predictors of fine root biomass and fine root surface area, and in particular, to test the correlation between fine root and leaf biomass and area
Piecewise power functions wereArea fitted to the first-order root branch biomass, fine root biomass

Summary

Introduction

Boreal forests play a critical role with respect to their contribution to global carbon dynamics [1].Mid- and high-latitude forests contain approximately 63% of the total carbon pool contained in global forest vegetation, and soils contain more than 66% of the carbon in forest ecosystems [2]. Accurate determination of carbon sequestration in forest ecosystems has been limited by the difficulty of finding an appropriate method to acquire a credible estimate of the production and turnover rate of fine roots [3]. Fine roots (diameter ≤ 2 mm) may only represent a small amount of the total forest biomass [4,5] Due to their short lifespan and rapid turnover rate, the production of fine roots accounts for approximately 33~60% of annual net primary production (NPP) in forest ecosystems [6,7,8]. Accurate estimation of fine root biomass and comprehensively understanding their dynamics are crucial for evaluating carbon and nutrient budgets of the whole terrestrial ecosystem [7]

Objectives

Methods

Results

Discussion

Conclusion