Abstract:

This study aimed to establish a scientific basis for the utilization of litter from greening tree species to enhance the content and composition characteristics of urban soils. As such, litter from eight common greening tree species, including Salix babylonica L., Acer pictum subsp. mono (Maxim.) H. Ohashi, Ginkgo biloba L., Sophora japonica L. var. japonica f. pendula Hort., Pinus tabuliformis Carrière, Juniperus formosana Hayata, Platycladus orientalis (L.) Franco, and Picea asperata Mast., was collected. The litter was then mixed with the disturbed surface soil from urban areas of Yan’an City at a 2% ratio (litter/soil, dry weight) and incubated for 120 d under conditions simulating natural soil density and moisture levels. Subsequently, changes in soil organic carbon, its components, and carbon pool indices were analyzed, along with their relationships with the chemical properties of the litter. Results revealed significant increases in soil organic carbon content with the addition of most litters, except for A. pictum subsp. mono and J. formosana, as well as significantly increased stable component content from other species except A. pictum subsp. mono, G. biloba, and J. formosana, with nearly all types of litter also markedly enhancing the moderately and highly activated components. In addition, treatment with S. babylonica, P. orientalis, P. asperata, and P. tabuliformis litter significantly increased the carbon pool index of the soil, with nearly all types of litter significantly increasing the lability index and carbon pool management indices of soil, but only P. orientalis litter treatment significantly increasing the carbon recalcitrant index. Correlation analysis identified negative associations between the levels of litter N and amino acids and both the content and components of soil organic carbon, as well as positive correlations between litter total phenols, soluble sugars, and C to N, C to P, and N to P ratios with the soil content of highly/slightly activated and stable carbons. Additionally, the content of litter organic acids, P, C, terpenes, phenols, and the C to N ratio exhibited positive relationships with moderately activated carbons in soil. To enhance the content, activity, and stability of organic carbon in urban soil, P. orientalis litter may be the preferred soil amendment, followed by litter from S. babylonica, P. asperata, and P. tabuliformis.

摘要：

本研究将垂柳（Salix babylonica L.）、元宝枫（Acer pictum subsp. mono (Maxim.) H. Ohashi）、银杏（Ginkgo biloba L.）、龙爪槐（Sophora japonica L. var. japonica f. pendula Hort.）、油松（Pinus tabuliformis Carrière）、刺柏（Juniperus formosana Hayata）、侧柏（Platycladus orientalis (L.) Franco）和云杉（Picea asperata Mast.）等8种北方城市常见绿化树种的凋落物与延安市城区受到频繁扰动的表层土壤以2%（凋落物/干土）的比例混合，在模拟自然条件下的土壤容重和含水量的基础上进行120 d的室内培养实验，检测处理后土壤有机碳及其各组分的含量以及相应碳库指数的变化，并分析凋落物化学特性与上述指标的关系。结果显示，8种供试凋落物中，除五角枫和刺柏外的所有凋落物处理均显著提高了土壤总有机碳含量，除五角枫、银杏和刺柏外的凋落物处理显著提高了其稳定组分的含量，而所有凋落物处理普遍显著提高了中等和高活性组分的含量。垂柳、侧柏、云杉和油松凋落物处理显著提高了土壤碳库指数，几乎所有处理均显著提高了土壤有机碳活度指数和碳库管理指数，仅侧柏凋落物处理显著提高了土壤固碳指数。凋落物氮和氨基酸含量与土壤有机碳各组分含量和相关碳库指数总体呈负相关；凋落物总酚和可溶性糖含量以及碳氮比、碳磷比和氮磷比与高活性、低活性和稳定有机碳组分含量呈正相关，其总有机酸、磷、总碳、萜类、酚类含量和碳氮比则与中等活性有机碳组分含量呈正相关。仅从提高土壤有机碳总量及其各组分含量，以及土壤有机碳活性和稳定的角度考虑，侧柏凋落物可作为处理城市土壤的优选材料，其次为垂柳、云杉和油松凋落物。