桉树林和马占相思林的林下植物多样性及其与环境因子的关系

Relationship between understory plant diversity and environmental factors in Eucalyptus robusta and Acacia mangium forests

2021年因海南热带雨林国家公园的建立,园内部分人工林停止经营并进入次生自然演替状态,使其林下植物较往年更为丰富,亟待研究.通过研究该区域林下植物组成、性状构成以及植物群落特征与环境因子的关系,在马占相思林设置了60个10 m×10 m的样方,桉树林设置了53个10 m×10 m的样方,详细记录了林下植物的信息,同时采用典范分析分析了桉树林与马占相思林林下植物群落的分布格局及其与环境因子的关系.主要结果如下:(1)马占相思林下维管束植物共计109科312属530种,桉树林林下维管束植物共计96科302属445种;(2)通过对研究区域的植物群落与环境因子进行典范分析(CCA),解释率达58%,能够较好地反映林下植物群落与环境因子的关系,其中年降水量、年平均气温、海拔、平均气温日较差、郁闭度对林下植物群落的影响显著(P<0.05);(3)林下植物多样性受多种环境因素相互作用的影响,海拔和郁闭度是影响热带雨林人工林林下植物群落特征最显著的生境因子,雨林的高湿高温环境对林下植物多样性有负面影响.这一研究结果深化了对马占相思和桉树林林下植物群落的了解,同时为该区域生态系统功能和生物多样性保护提供了科学基础.

In 2021,the Hainan Tropical Rainforest National Park was established,within which the operations of certain plantation forests were discontinued,the natural succession was happened,and the understory vegetation is exceptionally abundant.In the report,60 sample squares(10 m×10 m)were designated in the Acacia mangium forest,while 53 sample squares of the same size were designated in the Eucalyptus robusta forest.The findings are as follows:(1)The A.mangium forest harbors a total of 109 families,312 genera,and 530 species of vascular plants in the understory,whereas the eucalyptus forest encompasses 96 families,302 genera,and 445 species.(2)The canonical correspondence analysis(CCA)was performed,and the eigenvalues of Axis 1 and Axis 2 were determined to be 0.4954 and 0.3954,respectively,accounting for 58%of the total eigenvalues(1.5341),which elucidate the relationship between the understory plant communities and environmental factors.When annual precipitation,mean annual temperature,elevation,mean daily temperature variation were used as individual explanatory variable,the depression exhibited significant effects(P<0.05).(3)As the elevation increased,both the Shannon-Wiener and Simpson indices initially rose and then declined.Similarly,the Shannon-Wiener index,species richness,Simpson index,and species richness showed an initial increase followed by a decrease with increasing depression.With the increase of average annual temperature,the Shannon-Wiener index,Simpson index,and species richness all exhibited an initial increase followed by a decrease.The Shannon-Wiener index,Simpson index,and species richness decreased with increasing annual precipitation.