Co-dominant species fail to compensate after 13-year of dominant species removal in a Tibetan alpine grassland

Abstract

To better understand the dynamics of community resilience, it is crucial to examine the role of dominant species in maintaining ecosystem functions. Dominant species, due to their high abundance, are considered to maintain productivity after species loss. However, it remains unclear whether the community productivity can be maintained or restored by the remaining co-dominant species after the loss of the dominant species. Therefore, we hypothesized that after the loss of dominant species, the lost productivity would be maintained by the co-dominant species in the remaining community. This study, conducted over 13 years in an alpine grassland, investigates the compensatory responses of remaining species following the removal of each of two dominant species, Kobresia pygmaea (sedge) and Stipa purpurea (grass), both individually and in combination, under two nitrogen level scenarios. We found that while partial compensation (compensation index < 1) occurred in the remaining community, neither of the remaining dominant species effectively compensated for the loss of the removed species. Leguminous plants showed the most obvious positive response to the removal of dominant species, whereas forbs and sedges showed the most marked negative responses. In addition, fertilization does not promote the recovery of community productivity following removal of the dominant species. Our findings underscore the critical role of dominant species in sustaining productivity. In the face of the accelerating crisis of biodiversity extinction, priority should be given to protecting the dominant species and key functional groups in the region.