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

• Published in: Ecology and evolution Vol. 9; no. 21; pp. 12193 - 12201
• Main Authors: Li, Changbin, Zheng, Zhi, Peng, Yunfeng, Nie, Xiuqing, Yang, Lucun, Xiao, Yuanming, Zhou, Guoying
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.11.2019; John Wiley and Sons Inc; Wiley
• Subjects: aboveground biomass; belowground biomass; Biomass; Carbon; Climate change; Ecosystems; Experiments; Flowers & plants; Global climate; Grasslands; Hypotheses; Isometric; Nitrates; Nitrogen; nitrogen addition; Original Research; Plant biomass; Plant communities; Precipitation; precipitation changes; Soils; Steppes; Studies; Tibetan alpine steppe; Tibetan Plateau; China; belowground biomass; aboveground biomass; precipitation changes; Tibetan alpine steppe; nitrogen addition
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.5706

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. In summary, we demonstrated that altered precipitation and N addition led to changes in the relationship between aboveground and belowground biomass allocation. Moreover, we demonstrated that reduced precipitation had little impacts on aboveground and belowground biomass allocation, while it enhanced more biomass into deep soil. Therefore, our finding provides a novel insight into N and precipitation‐induced changes in the aboveground and belowground biomass allocation in the alpine steppe.