Vegetation of Mangroves: Spatial and Temporal Pattern of its Dominant Populations in Futian National Nature Reserve

The community characteristics of mangroves in the Futian Nature Reserve, Shenzhen, China are given based on surveying of 33 quadrats in 4 transects which stretch from the higher tidal zone to the lower tidal zone. The results show that there are 6 community types in this area: Kandelia candel association, Avicennia marina association, Aegiceras corniculatum association, Kandelia candel + Aegiceras corniculatum association, Aegiceras corniculatum + Kandelia candel association and Acanthus ilicifolius association. Kandelia candel, Aegiceras corniculatum and Avicennia marina dominate the typical quadrats. Kandelia candel can be seen at almost all quadrats, Aegiceras corniculatum distributes mostly toward the estuary and the higher tidal zone, Avicennia marina distributes mostly toward the bay and the lower tidal zone, Bruguiera gymnorrhiza occasionally occurs toward the Estuary with one or several individuals, Acanthus ilicifolius was common toward the higher tidal zone, as an accompanying species, Derris trifoliata was common in many mature quadrats. Totally, 6 species of mangrove plants and 3 species of semi-mangrove plants appear in this research area. From the higher tidal zone to the lower tidal zone, the average diameter and basal area of mangrove trees increase gradually. According to the results, the Avicennia marina dominates in average diameter and basal area, and the Aegiceras corniculatum trees are on the contrary. From the transect 1 to the transect 4, the importance value of Avicennia marina, Bruguiera gymnorrhiza and Kandelia candel decreases, and Aegiceras corniculatum increases. In this area, the Kandelia candel population and Aegiceras corniculatum population are developing populations with many seedlings and saplings, but the Avicennia marina population is in a mature stage with few seedlings and not so many total individuals. According to this research, we suppose that Aegiceras corniculatum should be developed toward the estuary and the Avicennia marina association should be protected.

Feature Analysis and Modeling of the Network Community Structure

Community structure has an important influence on the structural and dynamic characteristics of the complex systems.So it has attracted a large number of researchers.However,due to its complexity,the mechanism of action of the community structure is still not clear to this day.In this paper,some features of the community structure have been discussed.And a constraint model of the community has been deduced.This model is effective to identify the communities.And especially,it is effective to identify the overlapping nodes between the communities.Then a community detection algorithm,which has linear time complexity,is proposed based on this constraint model,a proposed node similarity model and the Modularity Q.Through some experiments on a series of real-world and synthetic networks,the high performances of the algorithm and the constraint model have been illustrated.