中国的红树林

<正> 在我国南部热带和亚热带海岸的盐滩,或海湾内河川出口的冲积盐性土上,广泛生着一片片深绿色的稠密的灌木或小乔木林,枝桠密布,涨潮时淹没过半或仅见顶部的树冠在海浪中漂荡,有如海上森林;退潮时则可见它的特有拱形支柱根和曲膝状的呼吸根,纵横交错,弯弯曲曲伸入浅水的淤泥中,形成一片特殊的植物群落,这就是植物生态学上所称的红树林(图1)。

Mangroves in China

SummaryMangroves are widely distributed along the seacoast of South China,inhabiting on the muddy tidal coasts of Guangxi and Guangdong. Because of the warm current of the Kuro Siwo, the mild climate enables them to grow as far north as Xiamen ( Amoy, 24°18'N)of Fujian Province and the Xinzhu harbour (25°10'N) of Taiwan Province. Those inhabiting on the coast of Hainan Island are the most exuberant, including 28 species belonging to 15 families. They are categorized as the eastern formation.According to their structure, phenotype and ecological environment, they may be classified into 3 communities.(1) The Dwarf Shrub Community, mostly distributed among the areas of higher latitudes. The dominant species of this community is Avicennia marina on the outer front of the sea beach. On the river outlet where the fresh water and the saline water meet is Aegiceras corniculatum.(2) The Dense Large Shrub Community, Because of the difference of temperature and variation of soil properties, the species that constitute this community are various. Nevertheless, they are all having the Rhizophoraceae as their dominant family, having the viviparous features. On the eastern sea coast of Hainan Island, where the temperature is high and the rainfall is ab-undant,Rhizophora stylosa is the absolute dominant species. On the flat muddy beaches or. the river outlets of Guangdong and Guangxi, Kandelia candel is dominant.(3) Tree Community, mainly distributed along the east and northeast coasts of Hainan Island. Their sites are of higher elevation, but still having sea water approaching the outer front of the site during the daily rising tide. Only during high tide can sea water approach the inner part of the site. The species that constitute the community are Bruguiera gymnorrhiza, B.sexangu-la and B. sexangula var. rhynchopetala. The trees may reach a height of 8 -10 meters with DBH of 30-40 centimeters. They are the Mangroves that yield highest volume of timber and have the most economic value among the mangroves of China.The mangroves of China are just like those in the other parts of the world, the dominant species are distributed distinctly in zones. Usually on the outer edges of the beaches and river outlets Sonneratia alba and Avicennia marina appear as pioneer species. On the middle parts where the sites are more favorable are-Rhizophora and Kandelia candel inhabiting. On the inner parts, Bruguiera is the main species, with some Xylocarpus granatum and Excoecaria agallocha constituting a mixed stand.The vast areas of mangroves in China are rich in resources , they may contribute large quantities of timber, fuel wood, tannin and also many kinds of medical materials. The mangroves will also act as buffer zones to protect the coastal banks from sea wave. Therefore it is necessary for the government to pass a law to protect the mangroves from denudation.