Abstract:

Ecological strategies related to the adaptation of plants to environmental stress have long been studied by ecologists, but few studies have systematically revealed the ecological process of plant adaptation to herbivores as a whole.

In this study, Stipa breviflora, the dominant species in the desert steppe of Inner Mongolia, was used to analyse its reproductive individual characteristics and seed traits as well as the soil seed bank and spatial patterns under heavy-grazing and no-grazing treatments.

The results showed that the number of reproductive branches positively affected the number of vegetative branches. The analysis of the soil seed bank showed that the density of S. breviflora seeds beneath reproductive S. breviflora individuals was significantly higher than that in bare land. The seed density was also significantly negatively correlated with the seed characteristics and the soil seed bank in bare land. The spatial distribution of S. breviflora was aggregated under heavy grazing. Our results suggest that under heavy grazing, reproductive activity plays a key role in resource allocation. Stipa breviflora evolved the ecological strategy of nearby diffusion by regulating the morphological characteristics of the seeds, which promotes a positive spatial correlation between the juvenile and adult populations at a small scale, thus leading to the formation of ‘safe islands’.

Key words: ecological strategy, grazing, reproductive individual, seed, spatial pattern