天目山自然保护区柳杉种群种内和种间竞争

Intra- and inter-specific competition within Cryptomeria fortunei populations in the Mountain Tianmu national nature reserve

调查了天目山自然保护区老殿、大树王和禅源寺3个柳杉典型样地,以研究竞争在柳杉种群衰退中的作用。结果表明,柳杉基本上是柳杉群落的单一优势种,相对优势度占58.79%～93.34%;单位面积内柳杉胸高截面积达59.96m2·hm-2,材积达904.9m3·hm-2。柳杉群落存在较严重的竞争,单木竞争指数以老殿最大,平均达4.35;大树王最小,平均为0.58。以竞争指数测度的竞争强度表明,种内竞争大于种间竞争。柳杉单株竞争强度与胸径成反比。认为种内竞争是导致柳杉种群衰退的重要原因之一。

Cryptomeria fortunei plays a critical role in the vegetation of the Mountain Tianmu national nature reserve.However,decline has been observed in the Cryptomeria fortunei forests in recent years.Three typical plots of C.fortunei forests were set for surveys in order to understand the role of competition in the decline.C.fortunei was the sole dominant species,accounting for 58.79%-93.34% of the total area at breast height in the surveyed communities.C.fortunei in Laodian plot suffered the most serious competition with a mean competition index per tree(CI)being 4.35.The mean competition index per tree of Dashuwang plot was 0.58,the lowest among the three.Intra-specific competition of C.fortunei,which contributed 57.3%-69.6% of the total CI,was higher than the inter-specific.Dashuwang CI was negatively correlated with diameter at breast height.The present study indicates that competition,especially intra-specific,plays an important role in the decline of C.fortunei in the Mountain Tianmu national nature reserve.