Different biomass allocation strategies of geophytes and non-geophytes along an altitude gradient

Abstract

Biomass allocation strategies among geophytes and non-geophytes generally determine the ecological adaptation and impacts of herbaceous plants. Although geophytes and non-geophytes are key components of the biodiversity of subtropical forest ecosystems, strategies for biomass allocation of both remain unknown. In this study, 695 individual herbaceous plants were collected from low, middle, and high altitude regions in Qianjiangyuan National Park. We analyzed the biomass and allometric trajectories of the leaves, stems, roots, and underground storage organs of whole herbs, geophytes, and non-geophytes. The results showed that: (1) The overall allometric trajectory of understory herbs changed with increase in altitude. Allocation was reduced to stems and leaves and increased to roots. (2) In geophytes, the allocation was reduced to leaves and stems and increased to underground storage organs and roots, which follows the optimal partitioning theory. In the biomass trade-off of the aboveground parts, the stem is preferred. (3) However, the allometric trajectories of non-geophytes are less susceptible to changes in the altitude, and the biomass allocation strategy depends only on plant size which follows allometric partitioning theory. In the biomass trade-off of the aboveground parts, the leaves are preferred. Totally, geophytes and non-geophytes adopted different biomass allocation strategies as adaptations to altitudinal changes in the environment. The plant functional type is the major determinant of biomass allocation in herb species. This study has implications for the management practices of herbaceous plants and predicting changes in understory vegetation.