Precipitation and nitrogen addition enhance biomass allocation to aboveground in an alpine steppe

Changbin Li; Zhi Zheng; Yunfeng Peng; Xiuqing Nie; Lucun Yang; Yuanming Xiao; Guoying Zhou

doi:10.1002/ece3.5706

Precipitation and nitrogen addition enhance biomass allocation to aboveground in an alpine steppe

Ecol Evol. 2019 Oct 4;9(21):12193-12201. doi: 10.1002/ece3.5706. eCollection 2019 Nov.

Authors

Changbin Li^{1

2

3}, Zhi Zheng^{1

2}, Yunfeng Peng⁴, Xiuqing Nie^{1

2

3}, Lucun Yang^{1

2}, Yuanming Xiao^{1

2

3}, Guoying Zhou^{1

2}

Affiliations

¹ Key Laboratory of Tibetan Medicine Research Northwest Institute of Plateau Biology Chinese Academy of Science Xining China.
² Qinghai Key Laboratory of Qing-Tibet Biological Resources Xining China.
³ University of Chinese Academy of Science Beijing China.
⁴ State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing China.

Abstract

There are two important allocation hypotheses in plant biomass allocation: allometric and isometric. We tested these two hypotheses in an alpine steppe using plant biomass allocation under nitrogen (N) addition and precipitation (Precip) changes at a community level. An in situ field manipulation experiment was conducted to examine the two hypotheses and the responses of the biomass to N addition (10 g N m^-2 y^-1) and altered Precip (±50% precipitation) in an alpine steppe on the Qinghai-Tibetan Plateau from 2013 to 2016. We found that the plant community biomass differed in its response to N addition and reduced Precip such that N addition significantly increased aboveground biomass (AGB), while reduced Precip significantly decreased AGB from 2014 to 2016. Moreover, reduced Precip enhanced deep soil belowground biomass (BGB). In the natural alpine steppe, the allocation between AGB and BGB was consistent with the isometric hypotheses. In contrast, N addition or altered Precip enhanced biomass allocation to aboveground, thus leading to allometric growth. More importantly, reduced Precip enhanced biomass allocation into deep soil. Our study provides insight into the responses of alpine steppes to global climate change by linking AGB and BGB allocation.

Keywords: Tibetan alpine steppe; aboveground biomass; belowground biomass; nitrogen addition; precipitation changes.