极小种群野生植物坡垒的生境特征及其对幼苗多度的影响

Habitat characteristics and its effects on seedling abundance of Hopea hainanensis,a Wild Plant with Extremely Small Populations

极小种群野生植物坡垒(Hopea hainanensis)曾经是热带低地雨林的优势种,但由于商业采伐和刀耕火种等严重人类干扰及自然更新困难,致使其种群数量急剧下降到最小可存活的界限,急需开展种群的拯救恢复工作。而对于坡垒生境适宜性及更新限制的了解,是进行种群保护及恢复的基础。本文在对野生坡垒种群及其生境因子调查测定的基础上,分析了生物与非生物生境特征及其对坡垒种群更新幼苗多度的影响。结果表明:坡垒种群从幼苗至幼树阶段存在着严重的增补限制。坡度小、土壤含水量和有效磷含量高、母株胸径和冠幅较大、伴生种胸高断面积中等的环境是坡垒幼苗较为适宜的生境,且坡垒幼苗多度与坡度及土壤pH值显著负相关,与土壤含水量及土壤全磷含量显著正相关。这些研究结果为极小种群野生植物坡垒的就地保护与种群复壮提供了科学依据。

Hopea hainanensis,a Wild Plant with Extremely Small Populations(WPESP),is a dominant species in the lowland rainforest on Hainan Island,China.Hopea hainanensis has populations well below minimum viable limits and is now at high extinction risk due to difficulties in regeneration and severe anthropogenic disturbances,such as commercial logging and shifting cultivation.Understanding the habitat requirements and regeneration limitations of H.hainensis is a critical first step to rescue and restore its natural population sizes.Here,based on observations and measurements of wild populations of H.hainanensis,we analyzed the effects of abiotic and biotic environmental factors on seedling abundance.Hopea hainanensis populations exhibited a severe recruitment limitation from the seedling to sapling lifestage.Seedlings occurred most often in habitats with low slope,high soil water content and soil available phosphorus with nearby mother trees with large DBH or crowns and around various species with moderate basal areas.Seedling abundance was negatively correlated with slope and soil pH.Our results provide rationale and direction for proper in situ conservation and population restoration of H.hainanensis.