J Plant Ecol ›› 2018, Vol. 11 ›› Issue (5): 780-788.DOI: 10.1093/jpe/rtx055

• Research Articles • Previous Articles     Next Articles

N and P resorption as functions of the needle age class in two conifer trees

Zhiyou Yuan1,2,*, Xinrong Shi1,2, Feng Jiao1,2,* and Fengpeng Han1,2   

  1. 1 State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China
    2 Institute of Soil and Water Conservation, Chinese Academy of Science and Ministry of Water Resource, Yangling, Shaanxi 712100, China
  • Received:2017-03-03 Revised:2017-09-12 Accepted:2017-09-19 Published:2018-09-27

Abstract:

Aims

Given the importance of resorption in nutrient conservations, nutrient resorption should change with leaf age if resorption depends on nutrient content, and if nutrient content changes with leaf age. However, no study has addressed this issue.

Methods

Here, we measured N and P concentrations of needles of different ages in two woody evergreen conifer species—white spruce (Picea glauca Voss.) and balsam fir (Abies balsamea Mill.)—to determine the effects of needle aging on nutrient resorption.

Important Findings

For both species, N and P concentrations were higher in newer needles than in older needles. Nutrient resorption efficiency, i.e. percentage of nutrients resorbed during senescence, also declined significantly with needle age from 73 to 22% in these two evergreen conifer species. The difference in nutrient resorption between old and young needles may be attributed to the size of N and P sink tissues, which is likely to decrease with needle age. These results suggest that needle age affects the extent of N and P resorption in these two evergreen conifer species.

Key words: evergreen conifer, needle age, nutrient resorption, Picea glauca, Abies balsamea