Above- and belowground biomass allocation in Tibetan grasslands

• Published in: Journal of vegetation science Vol. 20; no. 1; pp. 177 - 184
• Main Authors: Yang, Yuanhe, Fang, Jingyun, Ji, Chengjun, Han, Wenxuan
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.02.2009
• Subjects: Alpine grasslands; alpine plants; Alpine steppes; Belowground biomass; Biomass; dry matter accumulation; dry matter partitioning; Grassland soils; grasslands; Isometric Allocation; Meadows; nitrogen content; Optimal Partitioning; Plants; Qinghai-Tibetan Plateau; Root:Shoot Ratio; roots; shoots; Soil nitrogen; Soil water; soil water content; Steppe soils; Vertical Distribution; China
• ISSN: 1100-9233; 1654-1103
• DOI: 10.1111/j.1654-1103.2009.05566.x

Question: Optimal partitioning and isometric allocation are two important hypotheses in plant biomass allocation. We tested these two hypotheses at the community level, using field observations from Tibetan grasslands. Location: Qinghai-Tibetan Plateau, China. Methods: We investigated allocation between above-and belowground biomass in alpine grasslands and its relationship with environmental factors using data collected from 141 sites across the plateau during 2001-2005. We used reduced major axis (RMA) regression and general linear models (GLM) to perform data analysis. Results: The median values of aboveground biomass (\[M_A \]), belowground biomass (\[M_B \]), and root: shoot (R: S) ratio in alpine grasslands were 59.7, 330.5gm⁻², and 5.8, respectively. About 90% of total root biomass occurred in the top 30 cm of soil, with a larger proportion in the alpine meadow than in the alpine steppe (96 versus 86%). As soil nitrogen and soil moisture increased, both\[M_A \]and\[M_B \]increased, but R: S ratio did not show a significant change.\[M_A \]scaled as 0.92 the power of\[M_B \], with 95% confidence intervals of 0.82-1.02. The slope of the isometric relationship between log\[M_A \]and log\[M_B \]did not differ significantly between alpine steppe and alpine meadow. The isometric relationship was also independent of soil nitrogen and soil moisture. Conclusions: Our results support the isometric allocation hypothesis for the\[M_A \]versus\[M_B \]relationship in Tibetan grasslands.