Abstract: Based on the investigation data from 12 plots in Landqi Island of Minjiang Estuary, and by using age structure and aggregation indices, this paper analyzed the population structure, spatial pattern, and recruitment mechanism of Celtis sinensis forest on the island. The results showed that the C. sinensis population was stable, with an expanding age structure, and the seedlings were abundant, exhibiting stronger regeneration ability. The sprouts, accounting for 78% of the total seedlings, played an important role in maintaining population regeneration. There was a high mortality rate in seedling stage and small tree stage, but there were certain adult individuals. The population structure in different plots presented stable or decline type, and the spatial pattern had somewhat differences, with random distribution in plots 2 and 4, even distribution in plot 11, and clumped distribution in the others. The spatial pattern of C. sinensis population differed with developmental stages, showing a tendency of gradual transition from aggregation pattern to random pattern with the growth of C. sinensis seedlings.

Key words: Winter wheat, Potassium fertilizer, Grain filling stage, Photosynthetic characteristics