桂林岩溶石山落叶阔叶林种类组成及其环境解释

Species composition and environmental analysis of deciduous broad-leaved forests in karst hills of Guilin

关键词:  群落类型, 落叶阔叶林, 环境因子, 数量分类, 岩溶石山

Key words:  community type, deciduous broad-leaved forests, environmental factors, quantitative classification, karst hills

摘要:

为了解落叶阔叶林森林植被的群落类型和组成结构,该文在桂林阳朔县和灵川县岩溶生境典型的落叶阔叶林内设置49个20 m × 20 m的随机样方,在野外调查基础上进行群落数量分类和排序,对其群落类型进行划分,并对不同类型的群落种类组成、结构及其分布与环境因子的耦合关系进行分析。结果表明:(1)桂林岩溶石山落叶阔叶林可划分为3个群丛组类型,即群丛组A:南酸枣-喜树+巴豆群丛组(ASS. Choerospondias axillaris-Camptotheca acuminata+Croton tiglium),群丛组B:光皮梾木-喜树群丛组(ASS. Swida wilsoniana-Camptotheca acuminata),群丛组C:麻栎-檵木群丛组(ASS. Quercus acutissima-Loropetalum chinense)。(2)不同群落类型中常绿和落叶物种的丰富度、多度、胸高断面积及重要值的变化:在乔木层中,3个群丛组均为落叶物种占优势; 在灌木层中,群丛组A、B以落叶物种占优势,群丛组C以常绿物种占优势。(3)在1～5 cm和5～10 cm径级内,群丛组A、B的落叶物种在4个度量指标上均大于常绿物种,群丛组C除物种丰富度外,均为常绿物种大于落叶物种; 在 ≥10 cm径级中,除群丛组B的物种丰富度外,3个群丛组中的各项指标均为落叶物种占主导地位。(4)岩石裸露率、海拔、坡向、土壤含水量、土壤pH、土壤有机质、全氮、速效氮、速效钾、林冠开阔度和人为干扰是影响研究区不同类型群落分布的主要环境因子。

Abstract:

Deciduous broad-leaved forests are one of the typical forest vegetation types in the subtropical karst hills. In order to understand the community type and composition structure of this type of forest vegetation, we established forty-nine 20 m × 20 m random plots in deciduous broad-leaved forests with typical karst habitats in Yangshuo County and Lingchuan County of Guilin. We conducted an in-depth analysis of the coupling relationship from different community types, structures, and environmental factors. The results were as follows:(1)The deciduous broad-leaved forests in the karst hills could be classified into three community types based on quantitative methods, Ass. Choerospondias axillaris-Camptotheca acuminata+ Croton tiglium (Association Group A), Ass. Swida wilsoniana-Camptotheca acuminata(Association Group B), Ass. Quercus acutissima-Loropetalum chinense(Association Group C).(2)The species richness, species abundance, basal area, and the importance value for evergreen and deciduous species were different for each community type. Deciduous species were dominant in the tree layer for all three association groups. Shrub layer for Association Group A and Group B were also dominated by deciduous species, while Association Group C was dominated by evergreen species.(3)The species richness, species abundance, basal area and importance value of deciduous species in Association Group A and Group B were greater than evergreen species within the 1-5 cm and 5-10 cm diameter classes. In Association Group C, all indicators were greater for evergreen species than deciduous species for the 1-5 cm and 5-10 cm diameter classes. For the ≥10 cm diameter class, deciduous species were dominant for all indicators in all three association groups except for the species richness in Association Group B.(4)The rock bare rate, soil water content, elevation, aspect, pH, soil organic matter, total nitrogen, available nitrogen, available potassium, canopy openness and human disturbance gradient were the dominant factors affecting the distribution of different types of communities in the study.