对深圳马峦山郊野公园、田头山自然保护区和排牙山自然保护区中苏铁蕨[ Brainea insignis ( Hook.) J. Sm.]群落的组成、种群垂直结构和年龄结构进行了调查分析,并对 3 个群落物种的频度、多样性和均匀度进行了比较。根据群落中优势种的重要值与乔、灌木的分层,马峦山郊野公园、田头山自然保护区和排牙山自然保护区的苏铁蕨群落可分别命名为鸭脚木-豺皮樟-苏铁蕨群落、山乌桕-毛棉杜鹃-苏铁蕨群落和红鳞蒲桃+鸭脚木-豺皮樟-苏铁蕨群落。 3 个群落中,中低层(高度小于 10 m)的个体数均占群落个体总数的 90% 以上,随高度增加个体数量急剧减少。 以胸径反映优势种群的年龄结构,除苏铁蕨种群外,3 个群落的优势种群大都含有一定比例的Ⅰ级( DBH<2. 5 cm)幼树、Ⅱ级(2. 5 cm≤DBH<7. 5 cm)小树和Ⅲ级(7. 5 cm≤DBH<22. 5 cm)壮树,而Ⅳ级(DBH≥22. 5 cm)大树较少,显示 3 个群落具有不断更新的趋势。 马峦山郊野公园、田头山自然保护区和排牙山自然保护区苏铁蕨群落中频度级(FR)为 A 级(0% ≤FR<20% ) 的种类均占绝对优势,比例分别为 57. 50% 、63. 16% 和 61. 70% ,E 级(80% ≤FR≤100% )种类所占比例均较小,但马峦山郊野公园苏铁蕨群落 E 级种类比例大于 D 级(60% ≤FR<80% )种类,符合 Raunkiaer 群落频度分布定律。 3 个群落中,田头山自然保护区苏铁蕨群落的 Simpson 和 ShannonWiener 多样性指数和均匀度指数均最高,马峦山郊野公园苏铁蕨群落均最低。 研究结果表明,3 个苏铁蕨群落都处于演替中期,尚未达到顶极、亚顶极状态。


 

The composition, population vertical structure and population age structure of three communities of Brainea insignis (Hook.) J. Sm. in Maluanshan Country Park, Tiantou Mountain Nature Reserve and Paiyashan Mountain Nature Reserve in Shenzhen were investigated and analyzed, and frequency, diversity and evenness of species in three communities were compared. According to important value of dominant species and layer of arbor and shrub, B. insignis community in three regions above mentioned are named on Comm. Schefflera octophylla-Litsea rotundifolia var. oblongifolia-B. insignis, Comm. Sapium discolor-Rhododendron moulmainense-B. insignis and Comm. Syzygium hancei + S. octophylla-L. rotundifolia var. oblongifolia-B. insignis, respectively. Among the three communities, individual number in middle-low layer ( height less than 10 m) is more than 90% of total individual number of communities, and with increasing of height, individual number decreases sharply. Taking DBH to reflect age structure of dominant population, except B. insignis population, dominant populations of three communities almost have a certain proportion of Ⅰclass (DBH<2. 5 cm) saplings, Ⅱ class (2. 5 cm≤DBH<7. 5 cm) arborets andⅢ class (7. 5 cm≤DBH<22. 5 cm) adult trees, and a small proportion of Ⅳclass (DBH≥22. 5 cm) big trees, showing that three communities have a trend of constant renewing. Species with frequency rank ( FR ) A ( 0% ≤FR < 20% ) take an dominating advantage in the three communities above mentioned with a percentage of 57. 50% , 63. 16% and 61. 70% , respectively, but species with frequency rank E ( 80% ≤ FR ≤ 100% ) take a lower percentage. While the percentage of frequency rank E species is higher than that of frequency rank D (60% ≤FR<80% ) species in B. insignis community in Maluanshan Country Park, it is accorded with Raunkiaer’s law. Simpson’ s and Shannon-Wiener’ s diversity indexes and evenness index are all the highest in B. insignis community of Tiantou Mountain Nature Reserve in the three communities, while those are the lowest in Maluanshan Country Park. It is sugggested that three B. insignis communities all are in the middle stage of succession and don’t up to status of climax or sub-climax communities.