Effects of seed morphology on seed removal and plant distribution in the Chinese hill-gully Loess Plateau region

Seed was regarded as a limited factor of vegetation regeneration, and seed removal by water erosion may affect plant distribution on eroded slopes. This study aimed at understanding how seed morphology affects seed removal, consequently, interacts with plant distribution. Rainfall simulation experiments were conducted over 1 m2 plots with slope of 20° at intensity of 120 mm/h for 30 min, accompanying with vegetation survey of 70 sample plots from 16 eroded slopes. The seed loss ratio (SLR) of 60 species ranged 0–100%, while the seed displacement ratio (SDR) was 3.3–100% and the seed displacement distance (SDD) was 3.2–157.5 cm. Seed mass played a key role in the seed removal process, while seed shape, seed appendages, and seed ability to segregate mucilage could modify seed removal sometimes. Seed morphology resisting water erosion like big mass, extreme elongated shape, appendages, and mucilage segregation was useful for species to develop on eroded slopes. However, there was no uniform relationship between species distribution and seed removal by water erosion. Some species with seeds resisting water erosion prefer gentle slope to eroded slope, while some species with high seed removal can develop on eroded slope. Some species that distribute on eroded slope maybe mainly determined by plant strategies or soil surface characteristics.