喀斯特和非喀斯特森林植物磷含量及土壤无机磷分级特征比较

Comparison of plant phosphorus content and soil inorganic phosphorus classification characteristics between karst and non-karst forests

  • 摘要: 【目的】比较漓江流域喀斯特和非喀斯特森林植物叶片—根系—凋落物的磷含量及土壤磷含量和无机磷分级特征,为深入认识喀斯特森林磷循环过程,促进退化喀斯特森林生态系统恢复提供科学参考。【方法】在广西桂林漓江流域选取典型喀斯特和非喀斯特森林样地,采集植物叶片、根系和凋落物测定各组分磷含量,采集土壤样品测定总磷、速效磷和无机磷各组分含量以及土壤pH、含水率、碳氮含量等理化性质,分析植物磷与土壤磷各组分的相关性,明确喀斯特和非喀斯特森林磷养分的差异及其主要影响因素。【结果】喀斯特森林土壤总碳、总氮、可溶性有机碳和可溶性氮含量及碳氮比均显著低于非喀斯特森林(P<0.05,下同);喀斯特森林植物根系和凋落物磷含量(0.03%和0.04%)也显著低于非喀斯特森林(0.05%和0.11%);喀斯特森林土壤总磷含量为231.0 mg/kg,速效磷含量为2.2 mg/kg,均显著低于非喀斯特森林土壤(总磷含量609.0 mg/kg,速效磷含量9.3 mg/kg);2种森林类型土壤铁结合态磷(Fe-P)、闭蓄态磷(O-P)和钙结合态磷(Ca-P)均存在显著差异,喀斯特森林土壤无机磷组分以Fe-P为主,而非喀斯特森林土壤无机磷组分以O-P为主;喀斯特和非喀斯特森林植物叶片磷含量与土壤速效磷和铝结合态磷(Al-P)含量呈显著正相关,根系磷含量与土壤总磷、速效磷、Fe-P、O-P和Ca-P含量具有显著或极显著(P<0.01)相关性,而凋落物磷含量与土壤总磷、速效磷呈极显著负相关,与Fe-P呈显著正相关。【结论】漓江流域喀斯特与非喀斯特森林土壤总磷和速效磷含量及无机磷分级特征的差异在一定程度上影响着喀斯特与非喀斯特森林植被对土壤磷素获取和吸收,从而影响植物叶片、根系和凋落物磷含量。

     

    Abstract: 【Objective】To compare phosphorus content in leaves,roots,litters of plants and soil phosphorus content and inorganic phosphorus classification characteristics in karst and non-karst forests in the Lijiang River basin of Guangxi and to provide scientific reference for understanding the phosphorus cycle of karst forests and promoting restoration of degraded karst forest ecosystem.【Method】Sample plots were set up in karst and non-karst forests in the Lijiang River basin. Plant leaves,roots and litters were collected to determine phosphorus content,soil samples were collected to determine content of total phosphorus,available phosphorus and each component of inorganic phosphorus and analyze physical and chemical properties such as soil pH,water content,carbon content and nitrogen content. The correlation between plant phosphorus and different soil components was analyzed,the difference in phosphorus between karst and non-karst forests was determined and the main reasons were studied.【Result】The contents of total carbon,total nitrogen,dissolved organic carbon,dissolved nitrogen,and carbon to nitrogen ratio in karst forest soil were significantly lower than those in nonkarst forest soil(P<0.05,the same below);phosphorus content in roots and litters of plants in karst forest(0.03% and 0.04%)were significantly lower than those in non-karst forest(0.05% and 0.11%);total phosphorus content and available phosphorus content in karst forest soil were 231.0 and 2.2 mg/kg,respectively,which were significantly lower than those of non-karst forest soil(total phosphorus 609.0 mg/kg and available phosphorus 9.3 mg/kg);ferron-bounded phosphorus(Fe-P),occluded phosphorus(O-P)and calcium-bounded phosphorus(Ca-P)were all significantly different between the two types of forest;inorganic phosphorus in karst forest soil was mainly Fe-P,while the inorganic phosphorus in non-karst forest soil was mainly O-P;phosphorus content in leaves of karst and non-karst forest plants were significantly correlated with the content of soil available phosphorus and aluminum-bounded phosphorus(Al-P);and the phosphorus content in roots were significantly or extremely significantly(P<0.01)correlated with the content of soil total phosphorus,available phosphorus,Fe-P,O-P and Ca-P;while the phosphorus concentrations in litters were extremely significantly negatively correlated with the content of soil total phosphorus and available phosphorus,and were significantly positively correlated with Fe-P.【Conclusion】The differences in soil total and available phosphorus content and inorganic phosphorus classification between karst and non-karst forests in the Lijiang River basin may affect soil phosphorus acquisition and absorption in karst and non-karst forests vegetation,thus leading to variations of phosphorus content in plant leaves, roots and litters.

     

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