Response Of Seed Regeneration To Microsite In Natural Grassland

The study was conducted to test the response of seed regeneration to gap and litter disturbance in Bashang Agricultural ecotone grassland community, it aimed to find the safe site or safe microhabitat for each studied species, to verify the rare species’ seedling establishment showed low resource competition ability in existed vegetation than the common species, and to examine the suitable litter and seed position might be promote the seedling establishment of species in natural grassland. The study would clarify the reason of community structure change and dynamics of natural grassland during the rehabilitation succeed, enrich theory of species coexistence and species diversity maintenance, and provide theory basis for China northern grassland restoration, management and species diversity maintenance. The results indicated that,1. Gaps improved the seedling establishment of grassland species, and the seedling frequency for rare species and the low frequency species in grassland gap showed the higher values than those in the existed vegetation. Seedling establishment of most species need gap microsites, especially for small seed species, they usually need large gaps to establish, eg. rare species Adenophora stenanthina and Gentiana dahurica only established succeed in largest gap and the root gap.2. Gap obtain ability was related to characterize such as seed size, seed quantity, seed dispersal pattern. The establishment of rare species and the escape species were restricted by seed dispersal. Large seed species, Scabiosa comosa and Melissitus ruthenicus, and the long distance seed dispersal species eg. Cleistogenes quarrosa showed the higher gap obtain ability.3. Insect herbivory to seedling played an important role to seedling establishment in gaps. And the probability of seedling herbivore increased with the gap size increased. Seedling survival decreased significantly due to insect herbivory in gaps, especially for A. Stenanthina, Allium condensatum, G. Dahurica,and S. Comosa, over50%lost seedlings were found.4. Seedling emergence and survival of the4species (Saposhnikovia divaricat, G. Dahurica, S. comosa and A. stenanthina) was significantly promoted by100g m-2-200g m2litter. And biomass, height and leaves number of seedlings were much higher than those in the control by100-200g/m2litter cover. Therefore, conserving100g m-2-200g m-2of litter was benefit to seed regeneration in the enclosing management of nature grassland in Bashang area.5. Suitable seed position favored seedling emergence, survival and earlier growth performance. Seedling emergence and survival rates of the4species were higher in soil buried treatment. For earlier growth performance, G. Dahurica, S. divaricata S. comosa and A. stenanthina grew better soil buried treatment, while A. Stenanthina and S. divaricata showed better performance in between litter and soil treatment. In summary, seeds scattering on the litter surface were adverse to germination in the enclosed grassland, thus in order to maintain community structure and species diversity of natural grassland, appropriate disturbance should be provided in the course of enclosure to favor seed into soil and to promote seedling establishment.