江苏海州湾沿海沙滩植被的种类组成与群落变化

Species composition and community change of vegetation on coastal beaches of Haizhou Bay in Jiangsu Province

采用实地踏查方法调查了近年江苏海州湾沿海沙滩的分布状况、植被种类组成及群落变化,并与1980年代的相关调查结果进行了对比。结果表明:由于人为干扰严重,海州湾原有沙滩严重萎缩,沙生植被普遍遭到破坏、分布面积锐减,目前仅海头镇、大沙湾和苏马湾沙滩有植被分布,且只有海头镇沙滩分布的种类和群落数量较多。全部沙滩现有种类39种,比以前有所增加,并且新增的25种主要为内陆农田植物和山地植物,而典型沙生植物数量却有所减少;优势科、属不明显,其中只有1种的科数占总科数的70%左右;现存种类中植株数量在20株以下的有25种,占总种数的64.1%。植被组成种类的生活型没有明显变化,全部为冬季落叶性种类,且以地下芽植物和种子越冬植物占绝对优势,但生活型谱发生了变化。现存有7个群落,即砂引草群落(Tournefortia sibiricacommunity)、筛草群落(Carex kobomugi community)、肾叶打碗花群落(Calystegia soldanella community)、白茅群落(Imperata cylindrica community)、单叶蔓荆群落(Vitex rotundifolia community)、刺沙蓬群落(Salsola tragus community)和华黄耆群落(Astragalus chinensis community),其中华黄耆群落为新增群落;群落类型仍以草本群落为主(6个群落),建群种多为多年生草本植物、也是典型的沙生植物,且有些群落由共优种群落演变为单优种群落。群落原有的分布格局和演替序列有较大变化,群落分布面积明显减小;各沙滩拥有的群落数差异明显,其中海头镇沙滩分布有6个群落,而大沙湾和苏马湾沙滩则仅有1～2个群落;3个沙滩无共有群落,仅肾叶打碗花群落和单叶蔓荆群落分别为其中2个沙滩共有。在不同时期及不同沙滩各群落的各项多样性指数均有一定变化;各群落的丰富度指数均不同程度增加;多数群落的盖度和Shannon-Wiener多样性指数(SW指数)有所提高、Simpson多样性指数(SP指数)有所下降;在7个群落中,单叶蔓荆群落的丰富度指数、SP指数和SW指数均最高,白茅群落的SP指数和SW指数最低,刺沙蓬群落的丰富度指数最低。根据调查结果,对导致海州湾沙滩消失及植被变化的主因进行了分析,并提出相应的保护和改进措施。

The distribution status, species composition and community change of vegetation on coastal beaches of Haizhou Bay in Jiangsu Province in recent years were investigated by means of field survey, and those were compared with related investigation results in the 1980s. The results show that due to serious human interference, original beach in Haizhou Bay severely shrank, sand vegetation is generally destructed and its distribution area is sharply decreasing. At present, the vegetation only distributes in three beaches of Haitouzhen, Dashawan and Sumawan, in which, both of numbers of species and community distributing in Haitouzhen beach are relative more. There are 39 species existing in all beaches and species number increases than that of before, and newly added 25 snecies are mostlv inland farmland and mountain plants, while number of typical psammophyte decreases. Dominant families and genera are not obvious, in which number of family only containing one species accounts for about 70% of the total number of family. In existing species, there are 25 species with individual number below 20, which accounts for 64. 1% of total number of species. Life form of composition species in beach vegetation does not obviously change, they all are the winter deciduous species, and geophyte and seed overwintering plant are absolutely predominant, while only life form spectrum has changed. There are seven communities Vitex rotundifolia added community. of Tournefortia sibirica, Carex kobomugi, Calystegia soldanella, Imperata cylindrica, Salsola tragus and Astragalus chinensis, in which, A. chinensis community is a newly Community types are still mainly herbaceous community （6 communities） in which constructive species communities have c is mostly perennial herbaceous species, also is typical psammophyte, and some hanged There are larger changes from co-dominant species community to mono-dominant species community in original distribution pattern and succession series of these communities, and community distribution area obviously decreases. Community number in every beach differs obviously, in which, there are 6 communities in Haitouzhen beach, only 1-2 communities in Dashawan and Sumawan beaches. There are no common community among three beaches, only C. soldanella community and V. rotundifolia community are common for two beaches, respectively. There are some changes in every diversity index of all communities at different stages and in different beaches; the richness index of all communities increases with different degrees; the coverage and Shannon-Wiener diversity index （SW index） of most communities increase and Simpson diversity index （SP index） decreases. In seven communities, richness index, SP index and SW index are the highest in V. rotundifolia community, SP index and SW index are the lowest in I. cylindrica and richness index is the lowest in S. tragus community. According to the investigation results, main factors led to beach disappearance and vegetation change in Haizhou Bay are analyzed and the corresponding conservation and improvement measures are put forward.