吊罗山热带天然林物种多样性的海拔分布格局

Altitude distribution pattern of species diversity in tropical natural forest in Diaoluo Mountain

海拔梯度是影响物种多样性格局的关键因素。为探究吊罗山热带天然林物种多样性的海拔分布格局,该研究对吊罗山245~1130 m海拔内的6个热带天然林样地进行植被调查,从群落物种组成、物种多样性、区系组成和叶性质等方面分析沿海拔梯度吊罗山热带天然林物种多样性与群落特征变化规律。结果表明:(1)随海拔升高、温度降低、湿度升高、人为干扰减少,吊罗山热带天然林物种组成以及Margalef、Shannon-Wiener、Simpson、Pielou多样性指数均呈现先升高后降低的格局;中海拔群落水热条件最为适宜、人为干扰适中、α物种多样性最高。(2)随海拔升高,优势种重要值占比呈现先降低后升高的格局,且优势种具有明显的更替现象,中海拔群落呈现低地雨林与山地雨林的过渡性质。(3)群落间S rensen群落相似度和海拔高度差呈显著负相关(P<0.05)。(4)区系组成以热带区分布为绝对优势,并以热带亚洲(印度-马来西亚)分布为主;热带区分布比例和海拔呈极显著负相关(P<0.01),温带区分布比例和海拔呈极显著正相关(P<0.01)。(5)叶性质呈现出以中型叶、单叶、革质叶、全缘叶为主的热带地区显著特点;小型叶、单叶比例和海拔呈极显著正相关(P<0.01),革质叶、非全缘叶比例和海拔相关性不显著(P>0.05)。综上所述,吊罗山低海拔群落水热条件和人为干扰程度都与高海拔群落存在较大差异,从而导致了物种分布和群落特征的差异性,体现出热带植物与其生境条件相适应的特点。

Altitude is the key factor affecting species diversity pattern.In order to explore the altitude distribution pattern of species diversity in tropical natural forest in Diaoluo Mountain,vegetation survey was conducted in six tropical natural forest plots from 245 to 1130 m.The species diversity and community characteristics of tropical natural forest along the altitude of Diaoluo Mountain were analyzed from the aspects of species composition,species diversity,flora composition and leaf characteristics.The results were as follows:(1)With the increase of altitude,the temperature decreased,the humidity increased and the human disturbance decreased.The species composition of tropical natural forest in Diaoluo Mountain and the diversity indexes of Margalef,Shannon-Wiener,Simpson,and Pielou all showed a pattern of first increase and then decrease.The middle-altitude community had the most suitable hydrothermal conditions and moderate human disturbance,and theαspecies diversity was the highest.(2)With the increase of altitude,the proportion of important value(IV)of dominant species decreased first and then increased,and the dominant species had obvious replacement phenomenon.The middle altitude community showed the transition nature of lowland rain forest and mountain rain forest.(3)The S rensen community similarity coefficient between communities was significantly negatively correlated with altitude difference(P<0.05).(4)The floristic composition was dominated by tropical elements and mainly distributed in tropical Asia(India-Malaysia).The proportion of tropical distribution was significantly negatively correlated with altitude(P<0.01),and the proportion of temperate distribution was significantly positively correlated with altitude(P<0.01).(5)The leaf characteristics showed the obvious indigenous characteristics in tropical regions mainly with mesophyll leaves,single leaves,leathery leaves and entire leaves.The proportion of microphyll leaves and single leaves was significantly positively correlated with altitude(P<0.01),while the proportion of leathery leaves and non-entire leaves was not significantly correlated with altitude(P>0.05).To sum up,the hydrothermal conditions and human disturbance degree of low altitude community in Diaoluo Mountain are quite different from those of high altitude community,which leads to the difference of species distribution and community characteristics,and reflects the characteristics of tropical plants adapting to their habitat conditions.