深圳建成区城市绿地乔木层碳密度估算及分布特征

Estimation and Distribution Characteristics of Carbon Density in the Arbor Layer of Urban Green Spaces in Shenzhen's Built Area

为揭示深圳建成区城市绿地乔木层碳密度的空间分布特征及影响因素,基于树木异速生长模型对深圳各行政区不同城市绿地类型及不同龄林碳密度进行估算与分析。结果表明:1)深圳城市绿地乔木层平均碳密度为(4.494±0.345)kg·m^(-2);不同乔木林龄组碳密度存在较大差异,其中成熟林碳密度最高,近熟林、中龄林次之,幼龄林最低。2)不同类型的绿地乔木层碳密度差异较大,公园绿地乔木层平均碳密度最高(5.436±0.498 kg·m^(-2)),附属绿地次之(2.866±0.323 kg·m^(-2)),广场绿地最低(2.230±0.405 kg·m^(-2))。3)不同行政区绿地乔木层碳密度也存在较大差异,福田区、宝安区、罗湖区城市绿地乔木层的平均碳密度较高,光明区、龙岗区及龙华区相对较低。4)平均胸径、平均树高、林分密度、郁闭度和平均冠幅对城市绿地的乔木层碳密度影响显著(P<0.01),而材积密度与乔木层碳密度之间影响较弱。因此,通过在碳密度较低的绿地内适度增加乔木种植密度和大冠幅乔木,将会有效促进深圳市城市绿地固碳能力的提升。

In order to reveal the spatial distribution characteristics of and influencing factors to carbon density in the arbor layer of urban green spaces in Shenzhen's built areas,this study estimates and analyzes the carbon density of the urban green spaces of different types and the forests of different age in different administrative districts of Shenzhen based on the tree anisotropic growth model.The results show that:1) The average carbon density of the arbor layer in Shenzhen's urban green spaces is 4.494±0.345 kg·m^(-2),and there are large differences in the carbon density of different age groups of arbor forest,with mature forests having the highest carbon density,followed by near-mature forests and middle-aged forests,and young forests having the lowest;2) The carbon density of the arbor layer varies greatly among different types of green spaces,with the highest average carbon density in parks(5.436±0.498 kg·m^(-2)),followed by ancillary green spaces(2.866±0.323 kg·m^(-2)),and the lowest in plaza green spaces(2.230±0.405 kg·m^(-2));3) There are also large differences in the carbon density of the green space's arbor layer in different administrative districts,and the average carbon density of the arbor layer in the urban green spaces in Futian,Bao'an,and Luohu districts are higher,while that in Guangming,Longgang,and Longhua districts is relatively lower;and 4) The average diameter at breast height(DBH),average tree height(ATH),stand density(SD),degree of depression(DD) and average crown width(ACS) have a significant effect on the carbon density of the arbor layer in the urban green space(P<0.01) whereas timber volume density(TPD) has the lower effect on the carbon density of the arbor layer.Therefore,moderately increasing the planting density of trees and the number of large-canopy trees in green spaces with low carbon density will effectively enhance the carbon sequestration capacity of urban green spaces in Shenzhen.