Large plants enhance aboveground biomass in arid natural forest and plantation along differential abiotic and biotic conditions

Bai-Yu Yang; Arshad Ali; Ming-Shan Xu; Min-Sha Guan; Yan Li; Xue-Ni Zhang; Xue-Min He; Xiao-Dong Yang

doi:10.3389/fpls.2022.999793

Large plants enhance aboveground biomass in arid natural forest and plantation along differential abiotic and biotic conditions

Front Plant Sci. 2022 Oct 13:13:999793. doi: 10.3389/fpls.2022.999793. eCollection 2022.

Authors

Bai-Yu Yang^{1

2}, Arshad Ali³, Ming-Shan Xu², Min-Sha Guan¹, Yan Li², Xue-Ni Zhang², Xue-Min He², Xiao-Dong Yang^{1

2

4}

Affiliations

¹ Department of Geography & Spatial Information Technology, Ningbo University, Ningbo, China.
² Institute of Resources and Environment Science, Xinjiang University, Urumqi, China.
³ Forest Ecology Research Group, College of Life Sciences, Hebei University, Baoding, China.
⁴ Institute of East China Sea, Ningbo University, Ningbo, China.

Abstract

Big-sized trees, species diversity, and stand density affect aboveground biomass in natural tropical and temperate forests. However, these relationships are unclear in arid natural forests and plantations. Here, we hypothesized that large plants (a latent variable of tall-stature and big-crown, which indicated the effect of big-sized trees on ecosystem function and structure) enhance aboveground biomass in both arid natural forests and plantations along the gradients of climate water availability and soil fertility. To prove it, we used structural equation modeling (SEM) to test the influences of large plants located in 20% of the sequence formed by individual size (a synthetical value calculated from tree height and crown) on aboveground biomass in natural forests and plantations while considering the direct and indirect influences of species diversity as well as climatic and soil conditions, using data from 73 natural forest and 30 plantation plots in the northwest arid region of China. The results showed that large plants, species diversity, and stand density all increased aboveground biomass. Soil fertility declined aboveground biomass in natural forest, whereas it increased biomass in plantation. Although climatic water availability had no direct impact on aboveground biomass in both forests, it indirectly controlled the change of aboveground biomass via species diversity, stand density, and large plants. Stand density negatively affects large plants in both natural forests and plantations. Species diversity positively affects large plants on plantations but not in natural forests. Large plants increased slightly with increasing climatic water availability in the natural forest but decreased in plantation, whereas soil fertility inhibited large plants in plantation only. This study highlights the extended generality of the big-sized trees hypothesis, scaling theory, and the global importance of big-sized tree in arid natural forests and plantations.

Keywords: big-sized trees effect; climate water availability; niche complementarity effect; scaling theory; soil fertility.