| The island forest community is a major vegetation landscape of the Sanjiang Plain in northeastern China. Study on plant diversity is significant to local biodiversity conservation and marsh resource using rationally. However, the species diversity is confronted with a stress leading to forfeiture. Our objective were to 1) describe the flora characteristics, 2) clarify the level of plant diversity in the island forest community and 3) open out the relation between diversity indices and patch characteristics(area, perimeter and shape index ).Based on the Quick Bird satellite image data was used to identify a 6500hm2 area as study site. The quadrat method was used to investigate community patch characteristics such as area, perimeter and shape index. Four indices were selected to describe the plant diversity: richness index (R), Simpson index (D), Shannon-Wiener index (H′), and Pielou index (Jsw). Shape index (SI) was used to describe the shape of patches.The results demonstrated that, in 41 island forest communities, there were 161 species of vascular plants belonging to 45 families(102 genus), which comprised 8.9% of total vascular plant species in Heilongjiang Province and the compositions of plant flora were very complicated and rich. The seed plants with 98 genera are divided into 11 distribution types. There were the compositions of the temperate genera with 64 genera in 65.3%. The genera of single-species and fewer species had a large proportion of the plant flora, and distribution of families and genera were more decentralized. The polarization of diversity was different significantly. The plant flora reflects the areal-type of genera of seed plants were dominated by the temperate genera, the cosmopolitan genera also accounted for a considerable distribution advantages, and the tropical and subtropical flora have a certain proportion.The diversity indices R (p < 0.01), H′(p < 0.01) and D (p < 0.05) were significantly different among shrub layers of the Ass. Populus davidiana, Ass. Betula platyphylla and Ass. P. davidiana + B. platyphylla communities. But, they were not different among herb layer. Additionally, R, D and H′indices of different layers were as follows: herb layer > shrub layer > tree layer, with significant differences among them (p < 0.01). While significant correlation were observed between plant species richness and patch area (r = 0.406, p < 0.01), perimeter (r = 0.426, p < 0.01) and shape index (r = 0.367, p < 0.05), between D and patch area(r=0.331, p < 0.05) and between H′and patch area (r = 0.384, p < 0.05), perimeter (r = 0.312, p < 0.05). R,D and H′presented ascending trend with increasing of patch area, perimeter and shape index. The diversity levels were still higher relatively after human disturbance. The greatest diversity among different patches was noted in herb layers. Our data also suggested that gap disturbances were an important cause of higher underlayer diversity. Plant species richness increased with patch area, perimeter and shape index, most likely resulting from edge effects. Our results demonstrated that the island forest plays an important role in preserving plant diversity in the region. In the island communities, some plants had disappeared by comparing with the same communities in the Honghe Nature Reserve, such as Acer mono, Fraxinus mandshurica, Phellodendron amurense, Tilia amurensis, Acanthopanax senticosus, Lonicera maximowiczii, Deutzia amurensis, Schisandra chinensis and Actinidia kolomikta.
|
PDF Full Text Request