茂兰喀斯特森林梓叶槭种群结构与数量动态

Population Structure and Its Quantity Dynamics of Acer catalpifolium of Karst Forest in Maolan National Natural Reserve

梓叶槭是中国特有的珍稀濒危树种,国家二级保护植物,为了明确梓叶槭种群的结构特征及其种群生存现状,该研究在黔、桂交界处的茂兰国家级喀斯特森林自然保护区选取典型森林群落,应用每木调查法从梓叶槭高度(H)、径级结构、静态生命表、存活曲线和寿命期望等方面分析梓叶槭种群结构及其数量动态规律,为退化喀斯特森林生态系统的恢复重建提供理论依据。结果表明:(1)茂兰喀斯特森林中梓叶槭在群落中的重要值较低[槽谷(0.255),漏斗(0.243),坡地(0.188)]为非优势种。(2)梓叶槭种群主要分布在槽谷森林、漏斗森林和坡地森林等3种不同地形部位的群落类型中,在槽谷森林中分布数量最多,其次是漏斗森林,坡地森林中长势较差且数量最少。(3)梓叶槭在不同生境均严重缺乏Ⅰ径级[胸径(DBH)<2.5cm,H <33cm]个体,但Ⅱ径级(DBH <2.5cm,H=33cm)个体占较大的比例,中、大径个体较少,表现为稳定型种群。(4)不同生境梓叶槭种群存活数(除Ⅰ径级)随着径级增加而降低,死亡率(qx)和致死力(Kx)曲线大致呈上升趋势,生命期望单调下降,且Ⅰ径级在不同生境的死亡率均为负数,说明其幼苗严重不足,存活曲线趋于DeeveyⅡ型。研究认为,茂兰喀斯特森林中梓叶槭种群幼苗在发育过程中死亡率较高,而且受到的种间竞争较为激烈,加之茂兰喀斯特生境的严酷性和土壤营养空间缺乏,造成梓叶槭生长速度缓慢,故梓叶槭种群的衰退与严酷的喀斯特生境、人为干扰有关。

Acer catalpifolium is a rare and endangered tree species endemic to China,and is the second important protected plant in the country.In order to clarify the structure of A.catalpifolium population and analyze its current survival situation,we selected the typical forest communities in karst forest of Maolan National Natural Reserve were selected located at the junction of Guizhou and Guangxi.In this study,Using method of censusing every individual to analyze the population structure and population dynamics of A.catalpifolium we studied the aspects of height,diameter class,static life table,survival curve and life expectancy,providing theoretical basis for the population restoration,and reconstruction of forest ecosystems in degraded karst area.The results showed that:(1)the importance value of A.catalpifolium in the community is low[valley(0.255),funnel(0.243),hillside(0.188)],which is a non-dominant species in the Maolan karst forest of Guizhou.(2)A.catalpifolium population distributes in three community types of different topography sites:they are valley forest,funnel forest and hillside forest.A.catalpifolium grows the best with the most amount in valley forest,followed by funnel forest,but the worst and least in hillside forest.(3)A.catalpifolium in different habitats were serious shortage ofⅠdiameter class(DBH<2.5 cm,H<33 cm)individuals,butⅡdiameter class(DBH<2.5cm,H=33 cm)individuals accounted for a large proportion,the number of middle and large trees were less,characterized by a stable population.(4)In different habitats,the survival numbers of A.catalpifolium population(exceptⅠdiameter class)decreased with the increase of diameter.The curves of mortality(q x)and killing power(K x)showed an increasing trend,life expectancy decreased monotonically,and the mortality ofⅠdiameter class in different habitats was negative,indicating a serious shortage of seedlings.The survival curve tended to be the type DeeveyⅡ.As a result,the seedlings of A.catalpifolium have higher mortality during the development process in Maolan karst forest,and the interspecific competition is fierce.In addition,the harshness of the Maolan karst habitat and the lack of soil nutrient space cause the growth of A.catalpifolium to be slow.Therefore,the decline of A.catalpifolium population is related to the harsh karst habitat and human interference.