Environment and plant traits explain shrub biomass allocation and species composition across ecoregions in North China

摘要

Questions: Interspecific differences in plant biomass allocation reflect plant nutrient use strategy, determining species fitness under different environmental conditions. However, plant biomass allocation may be affected by both habitat and plant traits. We asked how environmental conditions and plant traits jointly affect shrub biomass allocation. Specifically, how they further play roles in understanding community species composition as ecoregion changes. Location: Shaanxi province, North China. Methods: Plant biomass, plant traits and community composition were surveyed for 48 shrub sites distributed in five ecoregions. Species-specific allocation parameters (allometric constants and scaling exponents) and plant traits were weighted with species abundance to calculate the community biomass allocation and community traits. Linear mixed models were used to assess relative contributions of plant traits and environmental factors in explaining biomass allocation pattern. Their roles in explaining species composition were analyzed by canonical correspondence analysis (CCA). Results: We reported that shrub biomass allocation parameters of stems vs leaves and roots vs shoots varied significantly among ecoregions. Plant traits explained more variation in stem vs leaf biomass allocation than soil and climate factors, while climate factors played important roles in variation of root vs shoot biomass allocation. Combined with plant traits and environmental conditions, biomass allocation showed a synergistic role in explaining community species composition. Conclusions: Environment and plant traits explain different aspects of shrub biomass allocation, and species-specific biomass allocation strategy have the potential to predict community species composition and distribution across ecoregions. Our study sheds light on the biomass allocations significance in understanding species turnover and community distribution.