喀斯特生境不同功能型植物根系中AM侵染与氮磷含量的关系

The Relationship between AM Infection and Nitrogen and Phosphorus Content in Roots of Different Plant Functional Types in Karst Habitat

【目的】高度异质的喀斯特生境中维持了丰富的植物物种。丛枝菌根(Arbuscular mycorrhiza,AM)在促进植物养分吸收及维持物种之间的功能关系具有重要作用,研究喀斯特生境不同功能型植物根系中AM侵染与植物氮磷含量的关系对深入探索喀斯特物种多样性维持机制具有重要意义。【方法】选取典型喀斯特生境植物群落为对象,按乔木型、灌木型、草本型和藤本型划分功能型,在半径为3m的样圆内选取香樟(Cinnamomum camphora)作为供体植物标记15 N同位素,测定了样圆内所有植物叶片δ15 N值及氮(N)与磷(P)的含量、根系AM侵染率、根际土壤孢子密度等。【结果】供体香樟中的15 N向样圆内所有植物转移,植物功能型差异和物种的差异明显影响了植株叶片的δ15 N值;乔木型植物的根际土壤孢子密度、叶片N含量及δ15 N值最高,香樟的根际土壤孢子密度和叶片δ15 N值最高,而女贞(Ligustrum lucidum)叶片N含量最高;灌木型植物叶片的N含量、P含量、N与P的含量比、δ15 N值以及根系AM侵染率、根际土壤孢子密度最低,其中烟管荚蒾(Viburnum utile)的根系AM侵染率和根际土壤孢子密度为0;草本型植物的根系AM侵染率和叶片P含量最高,其中丝叶薹草(Carex capilliformis)的叶片P含量和根系AM侵染率最高,但叶片N含量最低。【结论】喀斯特生境中不同功能型植物叶片氮磷含量及氮转移量存在差异,不同植物的根系AM侵染率与根际土壤孢子密度、叶片P含量有明显的正相关关系,叶片δ15 N值与叶片N含量、根际土壤孢子密度有明显的正相关关系。

[Purposes]The heterogeneous karst habitat maintain rich plant species.Arbuscular mycorrhiza(AM)plays an important role in promoting nutrients uptake and maintaining functions for plant species.The aim is to explore maintaining mechanism of plant diversity in karst area via researching on the relationship between AM infection and nitrogen and phosphorus content in roots of different plant functional types in karst habitat.[Methods]The typical karst plant communities were selected as an object,which were divided into functional types by arbor,shrubs,herbs and vines.The Cinnamomum camphorasapling was selected as the donor plant to mark the 15 N isotope in the sample circle with a radius of 3 meters,and then,the related indexes of all receiver plants were measured such as theδ15 N value,nitrogen(N)and phosphorus(P)content of leaf,root mycorrhizal infection and spore density.[Findings]The 15 N of donor C.camphoratransferred to all receiver plants in the sample circle,and the differences of plant types and species differences both significantly affected theδ15 N value in plant leaf.The arbor had the highest value of mycorrhizal spore density,N content and theδ15 N.In addition,the mycorrhizal spore density andδ15 N value of C.camphora was the highest respectively,while the highest N content was Ligustrum lucidum.Shrub had the lowest value of root colonized rate,spore density,N and P content,N:P andδ15 N,and the root colonized rate and spore density of Viburnum utile were both 0.The herb had the highest value of mycorrhizal colonized rate and P content.The colonized rate and P content of Carex capilliformis was the highest respectively,while the N content lowest.[Conclusions]The relationship between N content and N∶P were extremely significant in different species and different functional types.In different species the obvious significant correlations were found among the mycorrhizal colonized rate,mycorrhizal spore density and P content,and theδ15 N value was obvious significantly correlated to the N content and mycorrhizal spore density respectively.