海南岛吊罗山蕨类植物的多样性及其保育

Biodiversity and conservation of pteridophytes from Diaoluo Mountain, Hainan Island

对海南岛吊罗山的蕨类植物进行了专题研究。吊罗山有蕨类植物 4 3科 10 0属 2 13种及 4变种 ,其中 5种为海南新记录。蕨类物种密度高达 5 5 .8种 / 10 0km2 ,为海南蕨类多样性中心之一。该地蕨类植物区系以水龙骨科和膜蕨科为优势科 ,表现出明显的热带性质 ,热带分布的科、属、种分别达到 10 0 %、93.2 %和 95 .3%。在垂直分布上 ,蕨类植物的生态特点与植被类型相关 ,随着海拔升高 ,阳生性蕨类减少 ,阴生性蕨类、附生与石生蕨类增多 ,蕨类物种多样性在海拔 6 0 0～ 10 0 0m地段最为丰富。按照 2 0 0 1年IUCN红色名录等级及标准评估 ,在海南岛范围内 ,吊罗山有 36种受威胁蕨类植物 ,其中 6种为极危物种 ,13种为濒危物种 ,17种为渐危物种 ,这 36种受威胁蕨类中有 8种属于国家II级保护植物。导致这 36种蕨类植物受威胁的原因主要有 :人为直接破坏。

We studied the pteridophyte flora of Diaoluo Mountain in SE Hainan. In total, 213 species and 4 varieties of 100 genera in 43 families of pteridophytes were recognized. The two dominant families of the flora were Polypodiaceae with 12 genera and 24 species, and Hymenophyllaceae with 11 genera and 17 species. Five species collected recently from Diaoluo Mountain, i.e. Lygodium subareolatum, Pteris longipinnula, Pteris longipes, Allantodia deoderleinii and Dryopteris fuscipes, are new records to Hainan Island. Diaoluo Mountain is one of the centres of pteridophyte diversity in Hainan with a high species density of 55.8 species per centum square kilometer. Its pteridophyte flora is characterized by tropical distribution elements, represented by 100% tropical families, 93.2% tropical genera and 95.3% tropical species (excluding cosmopolitan taxa). Its flora is closely related with that of Indo China and that of Guangdong and Guangxi Provinces of China. The altitudinal distribution of pteridophyte can be divided into three zones: 30% of the pteridophytes are distributed in tropical rain forests and open area below 600 m, while 60.6% are mainly distributed in montane rain forests between 600～1000 m, and 9.4% are distributed in montane evergreen short forests above 1000 m. Most of the pteridophytes below 600 m are heliophytes, while those between 600～1000 m are sciophytes, and those above 1000 m are mainly epiphytes or lithophytes. According to 2001 IUCN Red List Categories and Criteria, 36 species are threatened on Hainan Island. Among them, six species are CR (Critically Endangered), 13 species are EN (Endangered) and 17 species are VU (Vulnerable). Eight of the 36 species are second class protected wild plants in China. The threatened species are mainly caused by drying of habitats. Because the primary forests had been destroyed on a large scale throughout the whole island, the water retaining capacity of the vegetation and soil has been decreasing for decades. In addition, human disturbance also accounts for some threatened species.