Dominant role of hyperdominance and large-sized trees in standing biomass and productivity of evergreen and deciduous broadleaf mixed forests in southwestern Hubei

This study systematically investigated the compositional characteristics of hyperdominance and large-sized trees, as well as their key roles in maintaining forest biomass and productivity, within the natural forest ecosystems of southwestern Hubei. The aim is to provide a theoretical basis and practical guidance for the conservation and sustainable management of forest vegetation in subtropical mountainous and hilly regions.

We used biophysical tree data from 6-hectare large plot in southwestern Hubei, China. We systematically analyzed the relative contributions of hyperdominance and large-sized trees to biomass and productivity, exploring the potential impact of these dominant tree species on regional forest carbon cycling and their key roles in maintaining forest ecosystem functions and stability.

A small number of hyperdominance contributed approximately 50% of species abundance (8 species), biomass (2 species) and productivity (5 species). The ranking of species abundance does not align with their biomass and productivity rankings, with notable differences observed. Species abundance showed a significant positive correlation with both biomass and productivity (R²>0.62, P<0.001), with higher species abundance contributing more to biomass and productivity. Approximately 1.00% to 3.39% of the big-sized trees contributed 34.29% to 68.94% of the biomass and 19.99% to 50.05% of the productivity. Species abundances of large trees were excellent predictors of their biomass (R²>0.98, P<0.001) and productivity (R²>0.86, P<0.001). Phylogenetic trees showed that hyperdominance and large-sized trees exhibited evolutionary clustering, primarily concentrated within specific families. These species played a key role in maintaining ecosystem functions.

Hyperdominance and big-sized trees play a crucial role in sustaining forest biomass and productivity. These dominant trees not only potentially affect regional forest carbon cycling but also have far-reaching implications for the long-term health and stability of forest ecosystems.