土地利用方式对西南喀斯特土壤碳、氮、磷化学计量特征及酶活性的影响

Effects of Land Use Types on Soil Carbon, Nitrogen, Phosphorus Stoichiometric Characteristics and Enzyme Activities in the Karst Area of Southwest China

    摘要
  • 摘要:
      目的  探究西南喀斯特土壤碳（C）、氮（N）、磷（P）化学计量特征和酶活性对不同土地利用方式的响应，有利于为西南喀斯特的土地利用调控与生态修复提供决策支持。
      方法  本研究以喀斯特高原峡谷（贵州省关岭县花江研究区）亚热带森林（SUF）、疏林（SPF）、灌木林（SHF）、草地（GL）、玉米地（CL）、裸地（BL）及弃荒地（AL）的土壤为研究对象，通过采集其0 ~ 15 cm土层样品，分析土壤C、N、P化学计量特征及酶活性的差异。
      结果  ①土壤有机碳含量（SOC）和全氮（TN）含量表现为SPF > AL > BL > SHF > CL > SUF > GL，土壤全磷（TP）含量表现为AL > BL > CL > SPF > GL > SHF > SUF。C∶N表现为SUF > AL > SPF > SHF > CL > BL > GL，C∶P表现为SPF > SUF > SHF > CL > AL > GL > BL，N∶P表现为SPF > SHF > SUF > CL > GL > AL > BL。土壤微生物量碳（MBC）含量则是SPF > SHF > CL > AL > SUF > BL > GL。②脲酶（URE）活性表现为SUF > CL > SPF > SHF > AL > GL > BL，蔗糖酶（SUC）活性表现为BL > AL > SPF > CL > SHF > GL > SUF，碱性磷酸酶（ALP）活性表现为SUF > BL > SHF > SPF > AL > CL > GL，过氧化氢酶（CAT）活性则是CL > AL > BL > SHF > SPF > GL > SUF。③URE与C∶P、N∶P、MBC极显著正相关，与C∶N显著正相关，与TP显著负相关；SUC与TP极显著正相关，与SOC、TN显著正相关；ALP与C∶N、C∶P显著正相关；CAT与TP极显著正相关，与TN显著正相关，与C∶P显著负相关。④在前两个排序轴中土壤理化因子累计解释了土壤酶活性变化的84.83%，按重要性排序依次为pH > 土壤温度 > TP > C∶P > TN > 容重 > SOC > C∶N > N∶P > MBC。
      结论  不同土地利用方式土壤C、N、P化学计量特征及酶活性存在显著差异，土壤N∶P < 14表明土壤养分主要受氮限制。影响酶活性的主要土壤理化因子为土壤pH、土壤温度和土壤全磷。

     

    Abstract:
      Objective  The responses of soil carbon (C), nitrogen (N), phosphorus (P) stoichiometric characteristics and enzyme activities on different land-use types are explored, in order to provide decision support for land use regulation and ecological restoration in the karst, southwest China.
      Method  Soils from subtropical forest (SUF), sparse forest (SPF), shrub forest (SHF), grassland (GL), corn land (CL), bare land (BL) and abandoned land (AL) were selected as research objects in karst plateau valley (Huajiang research area, Guanling county, Guizhou province), by collecting 0-15 cm soil layer samples, to analyze differences in soil C, N, P stoichiometric characteristics and enzyme activities.
      Result  ① Soil organic C (SOC) and total nitrogen (TN) contents showed SPF > AL > BL > SHF > CL > SUF > GL, soil total phosphorus (TP) content showed AL > BL > CL > SPF > GL > SHF > SUF. C∶N showed SUF > AL > SPF > SHF > CL > BL > GL, C∶P showed SPF > SUF > SHF > CL > AL > GL > BL, N∶P showed SPF > SHF > SUF > CL > GL > AL > BL. Soil microbial biomass C (MBC) content was SPF > SHF > CL > AL > SUF > BL > GL. ② Urease (URE) activities showed SUF > CL > SPF > SHF > AL > GL > BL, sucrase (SUC) activities showed BL > AL > SPF > CL > SHF > GL > SUF, alkaline phosphatase (ALP) activities showed SUF > BL > SHF > SPF > AL > CL > GL, catalase (CAT) activities showed CL > AL > BL > SHF > SPF > GL > SUF. ③ URE was extremely significantly positively correlated with C∶P, N∶P, and MBC, URE was significantly positively correlated with C∶N and significantly negatively correlated with TP; SUC was extremely significantly positively correlated with TP, SUC was significantly positively correlated with SOC and TN; ALP was significantly positively correlated with C∶N and C∶P; CAT was extremely significantly positively correlated with TP, significantly positively correlated with TN and significantly negatively correlated with C∶P. ④ In the first two statistics, soil physicochemical factors cumulatively explained 84.83% of the changes in soil enzyme activities, the order of importance was pH > soil temperature > TP > C∶P > TN > bulk density > SOC > C∶N > N∶P > MBC.
      Conclusion  There are significant differences in soil C, N, P stoichiometric characteristics and enzyme activities in different land-use types. Soil N∶P less than 14 indicates that soil nutrients are mainly limited by nitogen. Soil enzymes are mainly affected by soil pH, soil temperature and total phosphorus.

     

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