红树林景观空间结构分析方法

红树林是一种分布于潮间带的特殊森林,其生态系统与陆地生态系统无论在功能、作用,还是在物质和能量交换机制等方面都存在着很大的差异。为了探讨更适用于红树林景观空间结构的分析方法,笔者从红树林功能和作用方面,尤其是其消浪护岸作用的角度,讨论了海湾内理想的红树林空间分布,在此基础上定义了红树林丰度、空间分布均匀度、红树林岸线长度比例、高效护岸红树林面积比例4个红树林景观空间结构分析指标,介绍了根据红树林和海岸线空间分布图通过空间叠置分析计算这些指标的方法,并利用此方法对广西珍珠港、茅尾海和铁山港的红树林空间结构进行了分析。结果表明:这4个指标不但与红树林数量有关,也与其空间分布状态(斑块位置、形状、大小)以及与海岸线长度和空间位置有关,反映了红树林在海湾内的空间结构状态,既可用于同一时期不同海湾红树林数量的比较分析,也可用于同一海湾不同年度红树林数量的比较分析,并可对红树林景观空间结构进行优化。

An analysis method for landscape spatial structure of mangrove forest

The landscape pattern indexes were usually used to analyze the spatial structure characteristics of mangrove landscape, as the mangrove is a kind of special forest distributing only in the intertidal zone. Its ecological system is much different from the land ecological system in terms of function and role, the exchange mechanism of matter and energy, and so on. Therefore, it is necessary to develop a suitable method for analyzing its spatial structure in landscape level. In this paper, the Pearl bay, Maoweihai bay and Tieshangang bay in Guangxi were used as the study sites. We discussed the ideal distribution of mangrove within a bay or gulf by considering their function and role, especially their function of wave reduction and coastal protection.Four indexes were defined for analyzing their spatial structure in landscape level, including abundance of mangrove(AM,c_AM), evenness of mangrove distribution(EMD,c_EMD), ratio of mangrove coastline length to the total coastline length(RMCL,r_RMCL), and ratio of area of high efficiency coastal protection mangrove to the total area of mangrove(RAHP,r_RAHP). Then their calculation methods were developed based on the spatial overlay of maps of mangrove distribution and coastline. These four indexes related not only to the area and patch-number of mangrove, but also to their distribution state(patch location, shape and size)as well as the length and spatial position of coastline. With explicit physical meanings, they reflected the spatial structure of mangroves in a gulf or bay. These four indexes could not only be used for comparing the spatial structure of mangrove landscape of different bays in the same period, but also be used for analyzing the dynamic of spatial structure of mangrove landscape of the same bay in different period, and would be helpful for optimizing the spatial structure of mangrove landscape. Finally, the Pearl bay, Maoweihai bay and Tieshangang bay in Guangxi were used as the study sites for an empirical research.