Effects of warming and grazing on resource allocation strategies in alpine grasslands of the Tibetan Plateau: a meta-analysis

Abstract We screened 161 eligible papers of experimental data across the Tibetan Plateau for meta-analysis, in order to systematically assess and validate potential application of plant resource allocation strategies, such as the optimal allocation hypothesis, the isometric allocation hypothesis, and the allometric allocation hypothesis under environmental changes, and to explore the effects of environmental factors (temperature change, grazing intensity) on plant resource allocation strategies in alpine grassland ecosystems on the Tibetan Plateau. Overall, we found that the aboveground and belowground growth relationship in alpine grasslands follows the allometric growth hypothesis, which was unaffected by warming, grazing and their interactions. In addition, the biomass transferred between aboveground and belowground, the former was decreased, while the latter was increased under warming conditions in alpine steppe implies that the resource allocation strategy in alpine steppe grassland may potentially follow the optimal allocation hypothesis. We further found that the effect of soil properties on biomass, not the biomass allocation, was different under warming and grazing conditions in alpine grasslands, which further confirms the above conclusion. In addition, warming helped to mitigate the negative effects of grazing, which indicated that the interaction between warming and grazing is important in alpine grassland ecosystems. Overall, the results of this study are of theoretical significance for understanding how moderate grazing affects the growth of plants in alpine grasslands under changing climate.