南方丘陵红壤区森林土壤C、N、P生态化学计量特征及其影响因素

[Objective]Ecological stoichiometry plays an important role in understanding the constraints of soil nutrients on vegetation and maintaining forest ecosystem services.In order to clarify the ecological stoichiometric characteristics of forest carbon,nitrogen and phosphorus(C,N,P)and their influencing factors in the hilly red soil region of southern China,and to clarify the dominant nutrient elements of forest soil in this region,it provides a theoretical basis for sustainable forest management and soil improvement management in the hilly red soil region of southern China.[Method]In this study,a combination of random distribution,thematic distribution and forest distribution points was adopted,and based on high-resolution multi-source data such as terrain,hydrological information derived from DEM and vegetation information improved by DOM,a total of 323 sample points were set up,including 31 coniferous forests,98 evergreen broad-leaved forests and 134 coniferous and broad-leaved mixed forests(recorded as CF,BF and CBF,respectively).By measuring the contents of organic carbon(SOC),total nitrogen(TN)and total phosphorus(TP)in forest soil,and extracting the typical biodiversity indexes[normalized difference vegetation index(NDVI),nitrogen reflection index(NRI),leaf area index(LAI)and leaf photosynthetically active reflectance component(FPAR)]of the corresponding points,the ecological stoichiometric characteristics of C,N and P in forest soil and their influencing factors were evaluated and analyzed by geostatistics,Person correlation analysis and regression analysis.[Result]The results showed that the contents of SOC,TN and TP in BF soil were the highest among the three typical forest types.The changes of SOC and TN contents in different forest types were as follows:BF＞CF＞CBF,while the soil TP content was as follows:BF＞CBF＞CF.Among the three typical forest types,the soil C∶N,C∶P and N∶P in CF were the highest,and the soil C∶N,C∶P and N∶P belonged to moderate variation in coniferous forests,and belonged to strong variation in evergreen broad-leaved forests and coniferous and broad-leaved mixed forests.There was a strong correlation between soil SOC and TN,and both of them were mainly affected by altitude and soil pH,while the spatial variability of soil TP content was small.The stoichiometric ratios of soil C,N and P were mainly affected by environmental factors such as vegetation type,slope position,altitude and soil pH,and the altitude factor was positively correlated,while negatively correlated with soil pH.Among the soil nutrient factors,soil SOC content is the main influencing factor of soil C,N and P stoichiometry in this area.There was no significant relationship between soil C,N,P stoichiometry and biodiversity indicators.[Conclusion]In the soil of three typical forest types in the hilly red soil region of southern China,the soil SOC,TN and TP contents of evergreen broad-leaved forest were higher,and the soil nutrients were relatively rich.However,the TP content in the study area was relatively scarce,and the forest vegetation was mainly inhibited by P element.The stoichiometric ratios of soil C,N,and P were affected by altitude,soil pH,vegetation type,and slope position.The growth of forest vegetation in this area is relatively strong,and the ecosystem is relatively healthy.These results will help to improve forest management and forest soil conservation management.