Comprehensive Evaluation Of Landscape And Ecological Service Function Of Urban Greening Shrubs In Northern China

In the past,landscape greening mainly relied on the landscape service functions of tree species as the basis for selection,while neglecting their ecological service functions to improve the environment.At present,environmental issues such as particulate matter pollution,urban heat island effect and noise pollution occur frequently,so it is urgent to choose and apply tree species with strong comprehensive service functions to alleviate urban environmental pressure.In view of this,this article takes 26 common green shrubs in the northern China as the research object,and investigates and measures the functions of shrub species from both ecological and landscape services.The main content includes water conservation,dust retention,CO₂fixation,cooling and humidifying,noise reduction,green density,leaf viewing time（green leaf period）,and tree aesthetics.Then,a comprehensive evaluation model is constructed using principal component analysis to evaluate the tree species,And based on the evaluation results,cluster analysis is used to classify shrubs,in order to guide the selection and application of urban greening tree species.The major conclusions obtained are as follows:（1）In terms of specific functions of landscape services,the leaf density,thickness,viewing time and overall aesthetics of the tested shrub species are different.In terms of increasing the amount of green（referring to the amount of green per unit crown）,Chaenomeles speciosa,Ligustrum quihoui,Viburnum odoratissinum and Photinia fraseri are the best,Both leaf area density（>8.5 m²/m³）and leaf biomass density（>1.0 kg/m³）are relatively high;In terms of extending viewing time,except for evergreen shrubs,Spiraea thunbergii,Kolkwitzia amabilis and Rosa xanthina are the best（≥250 days）,while Berberis thunbergii’Atropurpuria’,Kerria japonica and Deutzia scabra are preferable（240-250 days）;In terms of improving the aesthetics of urban landscapes,Forsythia suspensa,Spiraea thunbergii,Amygdalus triloba,Photinia fraseri,Cerasus japonica and Chaenomeles speciosa are the best（>10 points）,Sorbaria sorbifolia,Viburnum odoratissinum,Cercis chinensis,Hibiscus syriacus,Weigela florida,Kolkwitzia amabilis,Kerria japonica,Deutzia scabra and Pittosporum tobira are good（9-10 points）.（2）According to the comprehensive evaluation and classification results of landscape service functions,in terms of improving urban landscape,Viburnum odoratissinum,Ligustrum quihoui and Photinia fraseri are the best（Y≥1.63）,and are the preferred tree species to decorate and beautify urban landscapes;The stem attached Chaenomeles speciosa and Buxus megalophylla are better（0.99≤Y<1.63）and can be used as secondary tree species;Nandina domestica,Pittosporum tobira,Euonymus japonicus’Aureo-marginatus’,Mahonia fortunei,Pyracantha fortuneana and Buxus bodinieri are moderate（0.24≤Y<0.99）and can be used to create multilevel landscapes and increase tree species diversity;Deutzia scabra,Cerasus japonica and Forsythia suspensa are general（-0.28≤Y<0.24）,and can be selected based on the characteristics of the trees and the purpose of greening;Berberis thunbergii’Atropurpurea’,Cornus alba,Kerria japonica,Punica granatum,Weigela florida,Weigela florida,Spiraea thunbergii,Hibiscus syriacus,Amygdalus triloba,Sorbaria sorbifolia and Cercis chinensis are relatively poor（Y<-0.28）,and can be used as backup tree species.（3）In terms of specific ecological service functions,there are also differences in the ecological service functions of different shrub species.In terms of effective water holding capacity of tree planting soil,Pittosporum tobira,Weigela florida,Viburnum odoratissinum,Pyracantha fortuneana and Ligustrum quihoui have the best（improvement rate>10.0%）,while Spiraea thunbergii,Punica granatum,Chaenomeles speciosa,Photinia fraseri,Kerria japonica and Weigela florida are better（9.0-10.0%）;In terms of the maximum water holding capacity of tree planting soil,Buxus bodinieri,Pittosporum tobira,Ligustrum quihoui and Viburnum odoratissinum have the best（with an increase rate of more than 14%）,while Nandina domestica,Weigela florida,Cerasus japonica,Pyracantha fortuneana,Cornus alba and Hibiscus syriacus are better（11-14%）;In terms of dust retention potential,Amygdalus triloba,Ligustrum quihoui and Viburnum odoratissinum have the best（>500 g/m³）,while Kolkwitzia amabilis and Pyracantha fortuneana are better（300-500 g/m³）;In terms of carbon sequestration capacity,the best ones are Chaenomeles speciosa,Photinia fraseri,Ligustrum quihoui and Viburnum odoratissinum（>500 g/m³）,while better ones are Pittosporum tobira（300-500 g/m³）;In terms of cooling and humidifying capacity,the best one is Chaenomeles speciosa（>200g/m²）,while better ones are Cerasus japonica,Pyracantha fortuneana and Ligustrum quihoui（100-200 g/m²）;In terms of noise reduction ability,Buxus megistophylla,Photinia fraseri,Chaenomeles speciosa,Viburnum odoratissinum and Ligustrum quihoui have the best noise reduction ability（≥14 d B/m³）,while Pittosporum tobira,Weigela florida,Kolkwitzia amabilis,Deutzia scabra,Forsythia suspensa and Hibiscus syriacus have better noise reduction ability（12-14 d B/m³）.（4）According to the comprehensive evaluation and classification results of ecological service functions,Ligustrum quihoui has the best ecological environment improvement（T≥3.04）and is the preferred tree species for ecological greening;Chaenomeles speciosa and Viburnum odoratissinum are better（1.52≤T<3.04）and can be used as secondary tree species;Pittosporum tobira,Pyracantha fortuneana and Photinia fraseri are moderate（0.70≤T<1.52）and can be used to improve the environment and increase tree species diversity;Deutzia scabra,Berberis thunbergii’Atropurpurea’,Kolkwitzia amabilis,Buxus bodinieri,Forsythia suspensa,Buxus megistophylla,Kerria japonica,Cerasus japonica,Hibiscus syriacus,Euonymus japonicus’Aureo-marginatus’,Nandina domestica,Weigela florida,Amygdalus triloba,Spiraea thunbergii,Cornus alba and Punica granatum are generally（-0.68≤T<0.70）,and can be selectively developed and applied according to their characteristics;Mahonia fortunei,Sorbaria sorbifolia and Cercis chinensis are relatively poor（T<-0.68）and can be used as backup tree species.（5）The comprehensive evaluation of the landscape service function and ecological service function of shrubs shows that in terms of enhancing the urban landscape effect and improving the ecological environment,Ligustrum quihoui and Viburnum odoratissinum are the best（Z≥2.86）,and are the preferred tree species for urban green space construction;Photinia fraseri,Chaenomeles speciosa and Pittosporum tobira are better（1.38≤Z<2.86）and can be used as secondary tree species to improve and beautify the urban environment;Buxus megistophylla,Kolkwitzia amabilis,Buxus bodinieri,Spiraea thunbergii,Pyracantha fortuneana,Euonymus japonicus’Aureo-marginatus’,Nandina domestica,Deutzia scabra,Kerria japonica,Cerasus japonica,Weigela florida,Hibiscus syriacus,Amygdalus triloba and Forsythia suspensa（-0.89≤Z<1.38）,and should not be widely used.They can be selected based on a certain service function that performs better;Sorbaria sorbifolia,Cornus alba,Weigela florida,Mahonia fortunei,Cercis chinensis,Berberis thunbergii’Atropurpurea’and Punica granatum are relatively poor（Z<-0.89）,and can be used as reserve resources to enrich tree species.