关键词: CO₂浓度廓线, 土壤气体, CO₂浓度增高, 方法

Abstract: Foliar nitrogen to phosphorus ratio (N∶P) is widely used as an indicator of soil nutrient availability and nutrient limitation. Therefore, it is necessary to determine the most sensitive plant tissue as the indicator of soil nutrient status. Pinus taiwanensisoccupies a wide range of habitats in the Wuyi Mountain, China. Here, soil, new and old leaves of P. taiwanensis from three altitudes (1100, 1500, and 1900 m a.l.s.) were sampled in Wuyi Mountain. The concentrations of carbon (C), nitrogen (N) and phosphorus (P) as well as δ¹⁵N values of soil, new and old leaves were measured. The stoichiometric ratios of C, N and P (i.e. C∶N, C∶P, N∶P) in soil and leaves were calculated, respectively. Results showed that there was no significant difference in soil N availability among different altitudes, while the δ¹⁵N of soil and leaves increased with altitude, indicating that N availability for plants increased with elevations. Soil total P and available P concentrations, and P concentration of leaves at 1100 m altitude were lower than those at 1500 and 1900 m altitudes, indicating that the availability of soil N and P may serve as a limiting factor to the growth of P. taiwanensisat low altitude. There was no significant difference in the N and P concentrations and N∶P of the new leaves of P. taiwanensis among different altitudes. There was no correlation between N∶P in new leaves and soil nutrients. However, the variation patterns of N and P concentrations in old leaves were similar to those in soils, and the N∶P ratio in old leaves were closely related to soil nutrients. Our results indicated that old leaves of P. taiwanensis were more sensitive to soil nutrient status than the new leaves along the altitudinal gradient, which is beneficial to exploring the response of plant growth to variation in soil nutrients in the context of future climate change.