红树林植被对大型底栖动物群落的影响

大型底栖动物是红树林生态系统的重要组成部分,从红树林大型底栖动物种类、红树林与其周边生境大型底栖动物群落的比较,以及生境变化对动物群落的影响等方面阐述了红树林植被与大型底栖动物群落的关系.从物种数量上看,软体动物和甲壳类动物构成了红树林大型底栖动物的主要部分.影响大型底栖动物分布的环境因素包括海水盐度、潮位和土壤特性等,但在小范围区域,林内动物的分布更多地与红树林植被特性和潮位有关.因此,由于红树林植被破坏或者恢复引起的生境变化,将导致大型底栖动物群落和常见物种种群的变化,尤其对底上动物影响明显；随着人工恢复红树林的发育,林内底栖动物的多样性相应增加,优势种也发生变化.相比位于相同潮位的无植被滩涂,红树林可促进潮间带生物多样性.

Impacts of mangrove vegetation on macro-benthic faunal communities

Mangrove ecosystems, found on marine coasts of the sub-tropics and tropics, have high biological productivity and rich faunal diversity. Mangrove ecosystems provide organic matter and nutrients critical to marine benthic fauna, primarily through litter-fall which is a major component of the detrital food chain. The macro benthic fauna, in turn, provide an important link between mangrove detritus at the base of the mangrove food web and consumers at higher trophic levels. Benthic fauna also may modify the physical and vegetation structure of mangrove ecosystems. Thus, the community of macro benthic fauna needs to be considered in mangrove restoration if holistic ecosystem restoration is to be achieved. This overview examines the current knowledge of macro benthic fauna in mangroves, and the effects of mangrove vegetation on the faunal community in China. In mangroves, mollusks and crustaceans are the major components of the benthic fauna, and this is a common phenomenon all over the world. In China, the mollusks are represented by more species in most studies; this is similar to that in east coast of the Americas, but different from those in other geographic regions. Dominant fauna varies with mangrove regions, but some species such as Cerithidea cingulata, Littoraia elanostoma, sesarmid crabs and fiddler crabs are common, and some of them are dominant. The community structure of macro benthos seems to be influenced by environmental conditions such as hydroperiod, salinity and sediment texture, but the small-scale distribution pattern of benthic fauna mainly depends on the factors with respect to tidal regime and mangrove vegetation. This is due, in part, to the effects mangrove vegetation has on the chemical characteristics of sediment like the organic matter content, total N and pH. Perhaps more important is the role that mangroves play in providing a solid substrate for gastropods and shade that ameliorates the harsh conditions caused by high temperatures and high evaporation rates. These factors are responsible for making levels of secondary biological productivity and faunal diversity in mangroves comparable to those in seagrass meadows and salt marshes. Recent studies carried out in Jiulongjiang Estuary, showed that the total number of animal species within mangrove forests was greater than that of adjacent non-vegetated tidal flats with similar hydrological, topographical and edaphic conditions, indicating that mangrove vegetation promotes intertidal biodiversity. Studies in Jiulongjiang Estuary also demonstrated that mangrove areas with different vegetation ages or species can support different macro benthic assemblages, and the natural/mature mangroves generally support higher faunal biodiversity than the young or disturbed forest. Studies on mangrove rehabilitation and deforestation have further shown that Uca crabs are more abundant in open areas, while gastropods and sesarmid crabs are likely to prefer closed canopy, suggesting that some of these well represented families of macro benthic fauna (e.g. Phascolosoma esculenta, Metaplax elegans, Uca arcuata, Sesarma plicata and L. elanostoma in Jiulongjiang Estuary) could be valuable indicators of ecological change as part of a long term mangrove monitoring. Despite these advances in knowledge of macro benthic fauna communities in mangroves, our understanding is still limited compared to other components of the mangrove ecosystem. Much of the earlier research has focused on the community structure or the biology of individual species, and continued research on inter-specific interactions and the inter-relationship between habitat and the biota is needed. Studies on the relationship between mangrove rehabilitation and macro benthic fauna also are limited and are important for coastal management.