Abstract: Plant spatial pattern and coexistence between different life forms have contributed to understanding species adaptation. Inter-dune low land is a key stage of Horqin Sandy Land ecosystem, with different life forms. Linetransect method was applied for vegetation investigation on 100 quadrats with a size of 1 m×1 m. Then, we chose fifteen species, which belong to three life forms and four families as research objects, to study their pattern and coexistence mechanism. Pattern indexes, ttest and χ²test showed that the spatial patterns of fifteen species were of aggregation; but there was much discrepancy in the intensity of aggregation, which may be related to seed dispersal, plant morphology and development and soil condition. The correlations among DI, CI, m^*, and GI were significantly positive, indicating that these indexes had same ecological meaning and could replace each other. The perennial species had more coexistence within the perennial life form but had less coexistence with other life forms, which might be due to the reason that the same life forms have more ecological niche overlap. Both Spearman correlation analysis and Pearson correlation analysis showed that a few leguminous plants had more coexistence with other families of perennial, which may benefit from the soil improvement and plant disease decline by legume. The species aggregation and species coexistence in different life forms resulted from the species’ adaptation to the environment. Further research on significant correlation of species could provide a support for sandy vegetation restoration.

Key words: resource distribution, offshore water of southern Zhejiang, Larimichthys polyactis, environmental factor.