Stoichiometric characteristics of plant and soil C,N and P in different forest types in depressions between karst hills,southwest China

The stoichiometric properties of plant carbon(C),nitrogen(N) and phosphorus(P) and their relationships with soil were studied in six dominant plant communities in three forest types,i.e.,plantation forest,secondary forest and primary forest in depressions between karst hills,southwest China.The C,N and P contents of both plant and soil had significant differences among the different forest types.Soil C and N contents were the highest in the secondary forest and the lowest in the plantation forest.Soil P content was the highest in the plantation forest and the lowest in the primary forest.Plant C and P contents were in the order of plantation forest primary forest secondary forest,and plant N content was the highest in the plantation forest and the lowest in the primary forest.Soil N:P,C:P and plant C:P ratios were significantly higher in the primary forest than in the other two forest types.There were no significant difference for the soil C:N ratio among the three forest types.Plant N:P ratio was the highest in the secondary forest and the lowest in the plantation forest.Plant C:N ratio was in the order of primary forest plantation forest secondary forest.There were significantly positive linear correlations between N and P contents,C:N and C:P ratios,C:P and N:P ratios of arbor leaves in the different forest types,and significant negative linear correlations between plant C:N and N:P ratios,and between soil C:N and N:P ratios.There were no significant correlations between plant and soil C,N,P contents and C:P ratio,suggesting that the supply of C,N and P from soil had little influence on plant C,N and P contents.