Publication Date:
2014-09-24
Description:
Seed size had been advanced as a key factor that influences the dynamics of plant communities, but there are few empirical or theoretical predictions of how community dynamics progress based on seed size patterns. Information on the abundance of adults, seedlings, soil seed banks and seed rains, and the seed weight of 96 species was collected in alpine meadows of the Qinghai-Tibetan Plateau (China), which had different levels of grazing disturbance. The relationships between seed weight-abundance patterns for adults, seedlings, the soil seed bank and seed rain in the plant community were evaluated using regression models. Results showed that grazing levels affected the relationship between seed size and abundance properties of adult species, seedlings and the soil seed bank, suggesting that there is a shift in seed size-species abundance relationships as a response to the grazing gradient. Grazing had no effect on the pattern of seed size-seed rain abundance at four grazing levels. Grazing also had little effect on the pattern of seed size-species abundance and pattern of seed size-soil seed bank abundance at levels a-c (no-grazing meadow, lightly-grazing meadow and moderately-grazing meadow), but there was a significant negative effect at level d (heavily-grazing meadow). Grazing had little effect on the pattern of seed size-seedling abundance at level a, but had significant negative effects at levels b-d, and the |r| values increased with grazing levels. This indicated that increasing grazing pressure enhanced the advantage of smaller-seeded species in terms of the abundances of adult species, seedlings, and soil seed banks, whereas only the lightly-grazing level promoted the seed rain abundance of larger-seeded species in the plant communities. This study suggests that grazing disturbances are favorable for increasing the species abundance for smaller-seeded species but not for the larger-seeded species in an alpine meadow community. Hence, there is a clear advantage of the smaller-seeded species over the larger-seeded species with increases in the grazing level. # doi:10.1890/14-0135.1
Print ISSN:
1051-0761
Electronic ISSN:
1939-5582
Topics:
Biology
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