银叶树群落优势树种分布与土壤环境、群落竞争的关系研究

The Relationship between Dominant Species Distribution and Soil Condition and Competition in A Heritiera littoralis Community

古树群落对研究群落演替和物种更新具有重要的研究价值。森林群落中,土壤环境和群落竞争是影响物种生长和分布的重要因子。为探究古树群落优势树种对土壤环境和种间竞争的响应差异,以深圳盐灶银叶树(Heritiera littoralis)群落为研究对象,设立样方进行群落和土壤性质调查,分析银叶树群落乔木层和灌木层的5种优势树种分布与土壤环境、种间竞争的关系。结果表明:土壤pH值、盐分、磷元素和钾元素含量是影响银叶树群落树种分布的主要土壤因子;乔木层优势树种的分布与群落多样性显著相关,且乔木层优势树种个体的分布显著影响灌木层个体的分布;银叶树对群落多样性和土壤环境的响应与其他优势树种呈相反趋势,随着群落多样性的增加和土壤盐分及pH值的降低,除银叶树外的其他优势树种重要值均呈上升趋势,银叶树重要值则呈下降趋势;银叶树幼树生长显著受群落多样性的影响。阴香(Cinnamomumburmanni)、假苹婆(Sterculia lanceolata)、海杧果(Cerbera manghas)、多毛茜草树(Aidia pycnantha)、九节(Psychotria rubra)和罗伞树(Ardisia quinquegona)等优势树种随着土壤养分,尤其是磷和钾元素含量的提高以及群落正向演替而稳定更新和生长,而银叶树幼树对群落竞争的敏感度很可能影响其种群在山坡、邻海海岸等土壤环境较好的生境中的更新和维持。因此,银叶树种群保育应考虑改善沼泽土壤环境以缓解土壤pH值和盐分过高产生的潜在胁迫,同时应持续跟踪银叶树幼苗幼树个体在山坡和邻海海岸生境中的生长状况。

Ancient forest is of great value in studying community succession and species regeneration. In forest community, soil condition and interspecific competition are two major factors influencing species development and distribution. To explore the response difference of dominant tree species to soil condition and competition in ancient forest, we set up plots in three habitats, i.e., inland swamp, hill and coast, in ancient Heritiera littoralis community in Yanzao, Shenzhen, and analyzed the relationship of 5 dominant species with soil and competition in tree and shrub layers based on field investigation. The results showed that:(1) Soil pH, salinity, the content of phosphorus and potassium were the major factors influencing tree individual distribution in this community;(2) In tree layer the distribution of dominant tree species were significantly correlated with community diversity, and the species distribution in tree layer greatly influenced that in shrub layer;(3) The response of H. littoralis to soil and competition was different from that of other dominant species. With increasing community diversity and decreasing soil pH and salinity, important value of H. littoralis decreased but increased for other measured species;And(4) the growth of H. littoralis saplings was significantly influenced by community diversity. The results suggest that many dominant species, such as Cinnamomum burmanni, Sterculia lanceolata, Cerbera manghas, Aidia pycnantha, Psychotria rubra and Ardisia quinquegona, are likely to have a better growth and regeneration with increasing soil nutrients especially phosphorus and potassium, and community succession. The results also suggest that H. littoralis saplings are sensitive to competition so that likely hinder the development of H. littoralis population, especially in habitats with good soil conditions such as hill and coast. This study provides insights on H. littoralis conservation. To relieve the stress of high soil pH and salinity on the growth of H. littoralis, actions should be taken to improve the soil condition in swamp habitat where soil pH and salinity are high. In addition, continuous monitoring of sapling individuals in hill and coast should be conducted to understand H. littoralis population dynamics in these habitats.