Mowing succession of species composition is determined by plant growth forms, not photosynthetic pathways in Leymus chinensis grassland of Inner Mongolia

Previous studies demonstrate that mowing inhibits tall species but facilitates short species and C-4 species. However, as each species has a growth-form and simultaneously a C-pathway, it is important to know whether the effects of mowing on a species is determined only or majorly by its growth-from or C-pathway. We test the hypothesis that mowing facilitates the growth of short species and of C-4 species, and disentangle the interactive effects of plant growth-forms and C-pathways on plant responses to mowing. We monitored plant production species by species in the grassland under mowing versus intact natural conditions over 30 years. We clustered all species into six plant growth-form groups and two C-pathways, and examined their dynamics. Mowing significantly (P < 0.05) increased short bunchgrasses (SG) and annual and biannual (AB) species and decreased tall grasses; mowing also significantly increased C-4 species (P < 0.01). However, as the C-4 species in the grassland are majorly SG and AB, and the mowing enhancement on C-4 SG and AB are respectively not greater than that on C-3 SG and AB, the C-4-pathway does not show a growth advantage under mowing, which suggests other plant traits such as phenology my also play an important role in plant response to mowing. Plant growth-forms instead of C-pathways play a dominant role in determining plant response to mowing disturbance in the grassland dominated by C-3-species. Our results provide new insights into the mechanisms of grassland succession, and have implications for management of the Inner Mongolia grassland.