长白山6种阔叶树测定树木叶面积的最适叶片数量

Optimal Number of Leaves Required for Estimating Leaf Area of Six Specie Trees in Changbai Mountain

2019年7—8月份,在长白山阔叶红松林中选取假色槭(Acer pseudo-sieboldianum)、色木槭(Acer mono)、蒙古栎(Quercus mongolica)、紫椴(Tilia amurensis)、糠椴(Tilia mandshurica)、拧筋槭(Acer triflorum)6个阔叶树种为研究对象,在采集叶片前将树木大小划分为3个径级(小径树木(D_(1))、中径树木(D_(2))、大径树木(D_(3))),由于6种阔叶树的性状差异,树木大小3个等级对应的胸径(D)大小不一致(假色槭,D≤10 cm为D_(1)、10 cm<D≤15 cm为D_(2)、D>15 cm为D_(3);拧筋槭,D≤10 cm为D_(1)、10 cm<D≤20 cm为D_(2)、D>20 cm为D_(3);其余4个树种,D≤15 cm为D_(1)、15 cm<D≤30 cm为D_(2)、D>30 cm为D_(3)),每个等级选择3~4棵样树,每个树种选取10株;针对选取的样树、新鲜倒木,将树冠划分为上、中、下3部分,应用高枝剪等工具在树冠中部的东、西、南、北4个方位以及树冠底部、树冠上部2个方位,共6个方位,分别选取生长状况良好的叶片20片,每株树共计选取120片叶片,6个树种共采集叶片7165片(假色槭1193片、糠椴1162片、蒙古栎1139片、拧筋槭1216片、色木槭1311片、紫椴1144片),作为抽样总体。应用Excel进行数据基础分析,获取6个树种、3个胸径等级、6个取样方位的叶面积平均值和标准误差;应用R 4.2.3中的单因素方差分析法(ANOVA)对6个树种的叶面积进行方差分析,并通过多重比较法(Tukey HSD法)分析不同树种之间叶面积的差异性;应用t.test函数计算不同胸径等级、不同取样方位的差异性,分析不同树种在区分胸径等级和取样方位时叶面积均值与总体叶面积均值的差异;应用t检验法和随机抽样法,分析不同树种确定树木叶面积的最适叶片取样数量、6个树种在区分胸径和取样方位时确定树木叶面积的最适取样数量。结果表明:①不同树种的最适叶片取样数量不同,与种内的叶片变异系数密切相关。②6个树种的最适叶片取样数量分别为,假色槭644片、色木槭750片、蒙古栎677片、糠椴648片、紫椴697片、拧筋槭701片。③在径级和取样方位时对叶片取样,除了紫椴选择中等胸径树木的西方位取样,其余5个树种在野外工作环境时可选取中等胸径树木的下方位进行取样,最适叶片取样数量分别为,假色槭30片、色木槭46片、蒙古栎17片、糠椴65片、紫椴39片、拧筋槭66片。④综合试验研究结果,在野外采样时,应针对树种、胸径和取样方位,选择最适叶片取样数量,不应统一选择理论数据的25~40片叶片。

In July and August of 2019,six broadleaf tree species(Acer pseudo-sieboldianum,Acer mono,Quercus mongolica,Tilia amurensis,Tilia mandshurica and Acer triflorum)were selected as research subjects in the broad-leaved Korean pine forest of Changbai Mountain.Prior to leaf collection,the trees were divided into three diameter classes:small-sized(D_(1)),medium-sized(D_(2)),and large-sized(D_(3)).Due to the differences in traits among the six broadleaf tree species,the chest diameter(D)corresponding to the three diameter classes varied as follows:for A.pseudo-sieboldianum,D≤10 cm for D_(1),10 cm<D≤15 cm for D_(2),and D>15 cm for D_(3);for A.triflorum,D≤10 cm for D_(1),10 cm<D≤20 cm for D_(2),and D>20 cm for D_(3);and for the other four species,D≤15 cm for D_(1),15 cm<D≤30 cm for D_(2),and D>30 cm for D_(3).Three to four sample trees were selected from each diameter class,and ten individuals were selected for each tree species.The crown of each selected tree and fresh fallen logs were divided into three sections:upper,middle,and lower.High branch pruning tools were used to collect 20 wellgrown leaves from four cardinal directions in the middle section of the crown(east,west,south,north),as well as two directions from the upper and lower sections,for a total of six directions and 120 leaves per tree.A total of 7165 leaves were collected from the six tree species(A.pseudo-sieboldianum:1193 leaves,T.mandshurica:1162 leaves,Q.mongolica:1139 leaves,A.triflorum:1216 leaves,A.mono:1311 leaves,T.amurensis:1144 leaves).MS Excel was used for basic data analysis to obtain the average leaf area and standard error for each tree species,diameter class,and sampling direction.One-way analysis of variance(ANOVA)in R 4.2.3 was used to analyze the leaf area differences among the six tree species,and the Tukey HSD test was performed for post hoc multiple comparisons.The t-test function was used to calculate the differences in leaf area between different diameter classes and sampling directions,analyzing the differences between the mean leaf area of each tree species in distinguishing between diameter classes and sampling directions and the mean leaf area of the entire population.The t-test and random sampling method were applied to determine the optimal number of leaf samples for determining tree leaf area for different tree species,as well as the optimal number of samples for different tree species in distinguishing between diameter classes and sampling directions.The results showed:(1)The optimal number of leaf samples varied among different tree species and was closely related to the coefficient of variation within each species.(2)The optimal number of leaf samples for the six tree species were as follows:A.pseudo-sieboldianum:644 leaves,A.mono:750 leaves,Q.mongolica:677 leaves,T.mandshurica:648 leaves,T.amurensis:697 leaves,and A.triflorum:701 leaves.(3)When sampling leaves based on diameter class and sampling direction,apart from T.amurensis where samples from medium-sized trees in the western direction were chosen,the other five tree species can be sampled from the lower direction of medium-sized trees in fieldwork environments.The optimal number of leaf samples for each species in these cases were as follows:A.pseudo-sieboldianum:30 leaves,A.mono:46 leaves,Q.mongolica:17 leaves,T.mandshurica:65 leaves,T.amurensis:39 leaves,and A.triflorum:66 leaves.(4)Based on the comprehensive experimental results,the optimal number of leaf samples should be selected according to the tree species,diameter class,and sampling direction during field sampling,rather than uniformly selecting 25 to 40 theoretical leaf samples.