琅岐岛3类森林群落的最小取样面积研究

Minimum sample area of three forest communities in Langqi Island

为科学设定琅岐岛森林群落物种多样性调查的最小面积,提高研究结果的准确性和节约调查成本,本研究在福州市琅岐岛采用巢式样方法开展海岛森林群落的种-面积曲线调查,设置20 m×20 m的样方,选择对数函数、幂函数和逻辑斯蒂3种模型分别拟合3种类型森林群落,即台湾相思(Acacia confusa Merr.)、柠檬桉(Eucalyptus citriodora Hook.f.)和朴树(Celtis sinensis Pers.)林,及其灌木层、草本层共3个对象的种-面积关系,利用赤池信息准则(AIC)选择出最优拟合模型计算3类群落3个对象最小取样面积。结果显示:(1)3类森林群落3个对象的种-面积关系的最优拟合模型都是幂函数拟合模型。(2)在满足精度为50%~90%时,台湾相思林群落及其灌木层、草本层的最小取样面积分别为113.5、68.9和24.4 m^(2);柠檬桉林群落及其灌木层、草本层的最小取样面积分别为153.1、69.6和41.4 m^(2);朴树林群落及其灌木层、草本层的最小取样面积分别为65.5、38和15.2 m^(2)。(3)可将琅岐岛森林群落的最小取样面积设置为10 m×15 m,灌木层最小取样面积设置为10 m×10 m,草本层最小取样面积设置为6 m×6 m。(4)最小样方面积与群落物种数量存在一定的正相关性,还会受群落差异、取样面积、人为干扰、偶见种等因素的影响。

This study aimed to establish the minimum area required for surveys of species diversity in forest communities in Langqi Island,Fuzhou,to improve research accuracy and reduce survey costs.Nest sampling of 20 m×20 m quadrats was employed to investigate species-area curves of forest communities on the island.Three models(logarithmic function,power function,and logistic function)were selected to fit three types of forest communities,namely Acacia confusa Merr.,Eucalyptus citriodora Hook.f.,and Celtis sinensis Pers.,as well as the species-area relationships of the shrub and herb layers.The optimal fitting model was selected using the Akaike Information Criterion(AIC)to calculate the minimum sampling area for the three species in the three communities.Results showed that:(1)Power function fit models were the best fitting models for the species-area relationships of the three target species in the three forest communities.(2)The minimum sam-pling areas for the A.confusa community,shrub layer,and herb layer were 113.5,68.9,and 24.4 m^(2),respec-tively,when sampling precision was set to 50%-90%.The minimum sampling areas for the E.citriodora com-munity,shrub layer,and herb layer were 153.1,69.6,and 41.4 m^(2),respectively.The minimum sampling areas for the C.sinensis community,shrub layer,and herb layer were 65.5,38.0,and 15.2 m^(2),respectively.(3)The minimum sampling areas for the forest community,shrub layer,and herb layer in Langqi Island were 10 m×15 m,10 m×10 m,and 6 m×6 m,respectively.(4)A positive correlation was found between the minimum sampling area and number of species in the community,which was also influenced by community differences,sampling area,human disturbance,occasional species,and other factors.