Stoichiometry characteristics of soil carbon,nitrogen and phosphorus of three forest types in southeast of Guizhou Province

【Objective】Exploring the contents of carbon,nitrogen,phosphorus and ecological stoichiometry characteristics of soil in different forest types in southeast of Guizhou Province,to reveal the nutrient distribution law of forest soil and provide a theoretical basis for nutrient management.【Method】Three forest types(Pinus massoniana forest,Cunninghamia lanceolata forest and shrubs forest) were selected as the research objects. Soil samples were taken at depth intervals of 0-20 cm,20-40 cm and 40-60 cm,the contents of soil carbon(SOC),nitrogen(TN),phosphorus(TP) were measured in different soil layers and their stoichiometric ratios were analyzed.【Result】The contents of SOC,TN and TP in 0-60 cm soil layer of the three forest types ranged from 10.24-25.72 g/kg,0.49-1.23 g/kg and 0.10-0.40 g/kg,respectively,and the contents of SOC,TN and TP in soil showed as shrubs forest>C. lanceolata forest>P. massoniana forest. With the increase of soil depth,the contents of SOC,TN and TP in the three forests showed a decreasing tendency,among which the contents of SOC and TN in the soils were significantly different(P<0.05,the same below). The soil C∶N,C∶P and N∶P in 0-60 cm soil layers of the three forest types ranged from 21.94-30.16,65.72-154.81 and 2.80-10.55,respectively. The soil C∶N showed as P. massoniana forest>shrubs forest>C. lanceolata forest in different forest types,and soil C∶P,N∶P showed as C. lanceolata forest>P. massoniana forest>shrubs forest. With the increase of soil depth,the contents of soil C∶N,C∶P in the three forests increased at first and then decreased,among which the soil C:P of C. lanceolata forest in the soils was significantly different. And the soil N∶P showed an increasing tendency in P. massoniana forest and C. lanceolata forest,and a decreasing tendency in shrubs forest,and there was no significant difference(P>0.05,the same below). Redundant analysis showed that slope was the dominant factor affecting the stoichiometric characteristics of soil C,N and P,and the explanatory rate reached 18.7%. Electrical conductivity also had a significant impact on it,and the explanatory rate reached 10.0%,while soil temperature had no significant impact on it,and the explanatory rate reached 3.1%.【Conclusion】Soil organic matter mineralization is fast,C content is high,and nutrient supply is limited by N and P in the study area,and slope is the main factor restricting soil N and P supply.