成都市绿地常见乔木降雨再分配及其穿透雨的空间异质性

Rainfall Redistribution of Common Tree Species in Chengdu City and Its Throughfall’s Spatial Heterogeneity

探讨成都市绿地常用8种乔木(杜英、天竺桂、金桂、桢楠、紫叶李、水杉、垂柳和银杏)的冠层水文特征,定量评价其冠层雨水再利用效率,可为节约型景观植物的选择及生态水文优化提供依据。于2021年随机监测10场降雨,收集总降雨量(TP)、穿透雨(TF)、树干茎流(SF)和冠层截留量(I)数据,结合乔木特征进行相关和回归分析,探究8种乔木冠层降雨再分配特征。结果显示:1)10场降雨总量为137.20 mm,穿透雨率(TF_(V))占降雨量的62.35%,树干茎流率(SF_(V))占2.00%,冠层截留率(I_(C))占35.66%;树种间I值差异虽不显著,但金桂和桢楠I_(C)值较高且显著高于杜英I_(C)值;金桂和桢楠的冠层截留能力强于其他乔木,杜英冠层截留能力最弱。2)TF、SF和I值均与TP呈极显著正相关(P<0.01),TP是乔木TF及TF_(V)的决定性因素;胸径与SF_(V)、树高与SF及SF_(V)之间均呈显著负相关,I、I_(C)与叶面积指数(LAI)呈显著正相关。3)乔木林下不同位置(1/3R、2/3R、3/3R)的TF及TF_(V)值差异显著,为3/3R>2/3R>1/3R,但其TF变异系数差异不显著,TF变异系数与TP值呈显著负相关(P<0.01)。可见,城市绿地中推广金桂和桢楠的种植更有利于增强绿地的雨水截留能力,有效抑制地表径流的产生。

This study of the characteristics of canopy hydrology of 8 species of arbor in Chengdu City,including Elaeocarpus decipiens,Cinnamomum japonicum,Osmanthus fragrans,Phoebe zhennan,Prunus cerasifera,Metasequoia glyptostroboides,Salix babylonica and Ginkgo biloba,and the quantitative evaluation of their canopy rainfall re-utilization efficiency,can provide basis for the selection of saving-oriented landscape plants and the optimization of ecological hydrology.Data about the total rainfall(TP),throughfall(TF),stemflow(SF),and canopy interception(I)of 10 rainfalls are monitored in 2021.Based on the correlation and regression analyses of arbor characteristics,the rainfall redistribution characteristics of the 8 tree species’canopy are generated.The results show that:1)Total amount of the 10 rainfalls is 137.20 mm,with the throughfall ratio(TF_(V)),stemflow ratio(SF_(V)),and canopy interception ratio(I_(C))at 62.35%,2.00%and 35.66%,respectively.Although there is no significant difference among I values of the 8 tree species,the I_(C)value of O.fragrans and P.zhennan is the highest,and significantly higher than that of E.decipiens.The canopy rainwater interception capacity of O.fragrans and P.zhennan is stronger than that of other trees,while that of E.decipiens is the weakest;2)TF,SF and I values are extremely significantly positively correlated with TP(P<0.01),which is the key factor affecting TF and TF_(V).The significantly negative correlations are observed between DBH and SF_(V),and between tree height and SF and SF_(V).Both I and I_(C)are significantly positively correlated with LAI_(C)and 3)There are significant differences in TF and TF_(V)values at different locations(1/3R,2/3R,3/3R)under arbor forest,which is 3/3R>2/3R>1/3R.However,there is no significant difference in the variation coefficient of TF,and TF’s coefficient of variation is negatively correlated with TP(P<0.01).To sum up,the extensive promotion of O.fragrans and P.zhennan in urban green spaces is more conducive to enhancing the interception ability of green space to rainwater,and effectively inhibiting the generation of surface runoff.