城市片林与城市草坪细根生物量特征

细根在城市绿地地下碳过程中扮演着重要的角色．本研究采用土芯法和WinRHIZO根系分析软件对福建省福州市区内城市绿地的细根现存生物量进行研究。结果表明：1）城市片林的细根生物量在1．15～2．60t／hm^2之间，低于草坪的细根生物量（1．34～4．45t／hm^2），总体上也低于多数亚热带天然森林的细根生物量．2）细根垂直分布总体规律是随深度的增加而减少，城市草坪上层细根生物量与下层细根生物量差异大于城市片林．城市草坪土壤中79％的细根集中于表层土壤（0—10cm），10～40cm土层中的细根生物量仅占20％，而各城市片林中仅有50％左右的细根集中于土壤表层0～10cm，10～30cm深度的土层中的细根生物量占30％，40～60cm的土层都仍有20％的细根存在．3）采用细根长度、直径建立双因素模型，对城市绿地细根生物量均有较好的拟合结果，但城市片林的模型拟合效果（R^2〉0．85）优于城市草坪（R^2为0．59～0．79）．鉴于草坪具有可观的细根生物量，其对城市土壤地下碳过程有着不容忽视的作用，因此今后还需进一步引入其他变量优化其细根拟合模型．

Characteristics of Fine Root Biomass in Urban Woodlots and Lawns

Fine root plays an important role in belowground carbon cycling of urban green space. In this study, existing fine roots biomass was measured in urban green space in Fuzhou by using soil core method and WinRHIZO root analysis software. The results indicated ： 1 ） the fine root biomass of urban woodlots was between 1.15 - 2. 60 t/hm2 lower than that of urban lawn （ 1.34 - 4. 45 t/hm2 ） and most of sub-tropical natural forests. 2 ） the vertical distribution of fine root is that it decreases with soil depth, while the difference of fine root biomass between up-soil and deep-soil in urban lawn is more obvious than that of urban woodlot. 79% of fine root in urban lawn is distributed in the surface of soil （0 - 10 cm） , only 20% of fine root is accounted for in the depth of 10 -40 cm. However, there is only about 50% of fine root in the surface （0 - 10 cm） of soil in the urban woodlot, 30% of that is in the depth of 10 - 30 cm and 20% of that still exist in the depth of 〉 40 cm. 3 ） The doublefactor regression （length and diameter） could estimate fine root biomass well in all urban green spaces. In addition, the fitting results in urban woodlot models （R2 〉 0. 85 ） were better than the urban lawn models （ R2 between 0. 59- 0. 79）. For the un-negligible effect of fine root biomass of lawn in the process of urban belowground carbon cycling, the other variables should be introduced into the model to optimize the fitting result in the future.