沈阳市3种行道树冠层孔隙度研究

为了深入研究树木的冠层特性，从冠层孔隙度方面入手，利用半球摄影法获取沈阳市常用行道树银杏、国槐、银中杨的冠层孔隙度图像，通过Gap Light AnalyzerV2.0计算出冠层孔隙度，并同步测绘树木的胸径、树高、冠幅；对3种乔木的孔隙度和生长参数分别进行单因素方差分析、回归分析。结果表明:1）3种乔木的孔隙度具有显著差异，Q_银中杨＜Q_国槐＜Q_银杏（Q为冠层孔隙度）；2）冠幅和胸径分别与冠层孔隙度呈极显著负相关（P＜0.01），高度与冠层孔隙度呈显著负相关（P<0.05），相关系数表明孔隙度受冠幅的影响大于受胸径的影响；3）对与冠层孔隙度相关系数较高的冠幅和胸径构建多元线性回归模型，分别为Q_国槐=44.808-2.218×W_国槐-50.545×D_国槐；Q_银杏= 45.637-2.613×W_银杏-43.156×D_银杏；Q_银中杨=33.084-3.834×W_银中杨+41.105×D_银中杨。本研究提供了冠层孔隙度与生长参数的关系，可为林下光环境、反演叶面积指数以及树木数字模拟提供有效参数和数据基础。

Canopy Porosity of Three Greening Tree Species in the Streets of Shenyang City

In order to deeply study the canopy characteristics of trees,based on the canopy porosity,hemisphere photography was used to obtain canopy porosity images of three common street trees in Shenyang,including mature Ginkgo biloba,Sophora japonica,and Populus alba×P.berolinensis.The canopy porosity was calculated by Gap Light Analyzer V2.0,the DBH,height and canopy width of the trees were measured simultaneously.The porosity and growth parameters of the three arbors were analyzed by one-way ANOVA and regression analysis.The results showed that 1) the porosity of the three types of trees showed significantly differences,with the level of Q _{P.alba×P.berolinensis}<Q_S.japonica<Q_G.biloba (Q represented canopy porosity).2) Canopy width and DBH were extremely,significantly,and negatively correlated with canopy porosity (P<0.01),and height was significantly and negatively correlated with canopy porosity (P<0.05),the correlation coefficient indicated that the influence of canopy width on porosity was greater than DBH.3) Linear regression models were constructed for the canopy width and DBH with high correlation coefficient of canopy porosity:
Q_S.japonica=44.808-2.218×W_S.japonica-50.545×D_S.japonica;Q_G.biloba=45.637-2.613×W_G.biloba-43.156×D_G.biloba; Q_{P.alba×P.berolinensis}=33.084-3.834×W_{P.alba×P.berolinensis}+41.105×D_{P.alba×P.berolinensis}.This study provides the relationship between canopy porosity and growth parameters,which can provide effective parameters and data basis for understory light environment,leaf area index inversion and digital simulation of trees.