土壤碳氮磷和酶化学计量特征对原始林转换的响应  

Responses of soil C,N,P,and enzyme stoichiometry to primary forest conversion

作　　者：肖华翠 梁万栋 李源钊 盛浩[1] 周萍[2] XIAO Huacui;LIANG Wandong;LI Yuanzhao;SHENG Hao;ZHOU Ping(College of Resources,Hunan Agricultural University,Changsha,Hunan 410128,China;Key Laboratory of Agro-Ecological Processes in Subtropical Region,Institute of Subtropical Agriculture,Chinese Academy of Sciences,Changsha,Hunan 410125,China)

机构地区：[1]湖南农业大学资源学院,湖南长沙410128 [2]中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,湖南长沙410125

出　　处：《森林与环境学报》2024年第3期225-232,共8页Journal of Forest and Environment

基　　金：湖南省重点研发计划项目“变更耕地地力快速提升关键技术研究与应用”(2023NK2026);国家自然科学基金项目“亚热带丘陵区典型农林用地底土有机碳稳定机理研究”(41571234);科技基础资源调查专项课题“长江中下游耕地质量要素收集与扩展”(2021FY100504)。

摘　　要：为了解区域典型农林用地土壤碳、氮、磷、胞外酶生态化学计量特征,采用时空代换法研究湘西北本底一致、土地利用史清晰的常绿阔叶原始林及其转换而来的人工林地、果园、坡耕地和水田0~40 cm土层中有机碳含量、全氮含量、全磷含量、胞外酶活性、计量比值及其与活性碳、氮、磷组分的关系。结果表明,与原始林相比,果园和坡耕地土壤有机碳、全氮、全磷含量的降幅(40%~79%)较高,且深层土壤(20~40 cm)和表土(0~20 cm)的降幅类似,表明原始林转换为果园、坡耕地不利于深层土壤有机碳和养分的保存。果园、坡耕地、水田和原始林土壤碳、氮、磷含量的比值无显著差异。杉木人工林土壤碳、氮、磷含量比值较原始林高60%~124%,说明人工林土壤存在较强的氮、磷素共同限制作用。与原始林相比,土地利用方式转换后,土壤胞外酶活性降低18%~64%;果园和坡耕地表土碳磷获取酶计量比(E_(C/P))也显著降低,而深层土壤E_(C/P)显著升高。土壤中碳含量、氮含量、磷含量、酶活性及其计量比值与活性碳、氮、磷组分含量显著相关。原始林转换导致表土和深层土壤中的碳含量、氮含量、磷含量、胞外酶活性大幅下降,微生物底物有效性降低,表明土壤质量/健康退化。土壤碳、氮、磷含量计量比和酶计量比值对原始林转换的响应较弱,对土壤健康的指示作用有待进一步探索。To elucidate the stoichiometric dynamics of organic C,N,P,and extracellular enzymes in soil in typical agricultural and forestry lands,primary evergreen broad-leaved forests and converted plantations,orchards,sloping croplands,and paddies with similar geographical backgrounds and clear land-use history in western Hunan Province were selected.The space-for-time substitu tion method was applied to reveal the effect of primary forest conversion on the contents of organic C,total N,and total P;activities of extracellular enzymes,including their:stoichiometric ratios;relationships with labile C,N,and P fractions at a soil depth of 0-40 cm.Compared to the primary forest,the contents of soil organic C,total N,and total P in the orchard and sloping cropland were much more greatly reduced(40%-79%)than that in plantations and paddies.The reduction was similar in topsoil and deep soil,indicating relatively unfavorable conditions for organic C and nutrient preservation in deep soil under orchards and sloping croplands.No significant differences in soil C-N-P ratios were observed among the orchards,sloping croplands,paddy fields,and primary forests.The C-N-P ratios in soil were 60%-124%higher in plantations than in primary forests,indicating co-limitation by N and P in the soil under the plantation.Theβ-glucosaminidase,β-N-acetyl glucosaminidase,leucine aminopeptidase,and acid phosphatase activities were reduced by 18%-64%in the converted land-use sites than in the primary forest.Compared to that of the primary forest,the stoichiometric ratios of C-and P-acquiring enzyme(E_(C/P))in the topsoil under the orchard and sloping cropland were significantly reduced,whereas the E_(C/P) ratios in the 20-40 cm deep soil were significantly increased.The contents of organic C,total N,total P,enzyme activities,and their ratios were significantly correlated with the contents of the labile C,N,and P fractions in soil.Primary forest conversion resulted in substantial reductions in soil organic C,total N,and total P contents and extracellul

关 键 词：湘西北 深层土壤 土壤养分 生态化学计量学 胞外酶活性 土地利用 

分 类 号：S153[农业科学—土壤学]