title: Role of phosphorus and nitrogen in photosynthetic and whole plant carbon gain and nutrient use efficiency in eastern white pine.
abstract: In white pine (Pinus strobus) seedlings grown in five forest soils from New York State, net photosynthetic capacity (Amax) plant-1was correlated with total foliar N plant-1(r2=0.57), but was more highly correlated with total foliar P plant-1(r2=0.82). There was no relationship (r2<0.01) between Amax [g leaf]-1and foliar N [g leaf]-1for the pooled data set, but there was a significant (P<0.001), but weak (r2=0.20) positive relationship between Amax [g leaf]-1and foliar P [g leaf]-1across all soils. However, within two of the five soils leaf N concentration was a significant (P<0.05) determinant of photosynthetic capacity. Due to differences in soil nutrient availabilities a large range in foliar P:N ratio (0.02-0.15) was observed, and the proportion of leaf P:N appeared to control Amax [g leaf N]-1. Whole plant nitrogen (NUE) and phosphorus (PUE) use efficiencies were well correlated with whole plant P:N ratio. In addition, NUE was well correlated with Amax [g leaf N]-1and PUE was well correlated with Amax [g leaf P]-1. However, NUE was not well correlated with PUE, and Amax [g leaf N]-1was not well correlated with Amax [g leaf P]-1. These results indicated that P and/or N limitations were important components of photosynthetic nutrient relations in white pine grown in these five soils and suggest that both P and N and their proportions should be considered in analyses of photosynthesis-nutrient relations.
authors.affiliation: Department of Forestry, University of Wisconsin-Madison, 53706, Madison, WI, USA.
authors.forename: P B
authors.initials: PB
authors.lastname: Reich
authors.affiliation: U.S. Rocky Mountain Forest and Range Experiment Station, 80526, Ft. Collins, CO, USA.
authors.forename: A W
authors.initials: AW
authors.lastname: Schoettle
keywords: Nitrogen; Nutrient use efficiency; Phosphorus; Photosynthesis; Pinus strobus