Phosphorus limitation of aboveground production in northern hardwood forests.

Academic Article


  • Forest productivity on glacially derived soils with weatherable phosphorus (P) is expected to be limited by nitrogen (N), according to theories of long-term ecosystem development. However, recent studies and model simulations based on resource optimization theory indicate that productivity can be co-limited by N and P. We conducted a full factorial N × P fertilization experiment in 13 northern hardwood forest stands of three age classes in central New Hampshire, USA, to test the hypothesis that forest productivity is co-limited by N and P. We also asked whether the response of productivity to N and P addition differs among species and whether differential species responses contribute to community-level co-limitation. Plots in each stand were fertilized with 30 kg N·ha-1 ·yr-1 , 10 kg P·ha-1 ·yr-1 , N + P, or neither nutrient (control) for four growing seasons. The productivity response to treatments was assessed using per-tree annual relative basal area increment (RBAI) as an index of growth. RBAI responded significantly to P (P = 0.02) but not to N (P = 0.73). However, evidence for P limitation was not uniform among stands. RBAI responded to P fertilization in mid-age (P = 0.02) and mature (P = 0.07) stands, each taken as a group, but was greatest in N-fertilized plots of two stands in these age classes, and there was no significant effect of P in the young stands. Both white birch (Betula papyrifera Marsh.) and beech (Fagus grandifolia Ehrh.) responded significantly to P; no species responded significantly to N. We did not find evidence for N and P co-limitation of tree growth. The response to N + P did not differ from that to P alone, and there was no significant N × P interaction (P = 0.68). Our P limitation results support neither the N limitation prediction of ecosystem theory nor the N and P co-limitation prediction of resource optimization theory, but could be a consequence of long-term anthropogenic N deposition in these forests. Inconsistencies in response to P suggest that successional status and variation in site conditions influence patterns of nutrient limitation and recycling across the northern hardwood forest landscape.
  • Authors

  • Goswami, Shinjini
  • Fisk, Melany C
  • Vadeboncoeur, Matthew
  • Garrison-Johnston, Mariann
  • Yanai, Ruth D
  • Fahey, Timothy J
  • Status

    Publication Date

  • February 2018
  • Published In

  • Ecology  Journal
  • Keywords

  • Ecosystem
  • Forests
  • New Hampshire
  • Nitrogen
  • Phosphorus
  • Soil
  • Trees
  • aboveground productivity
  • co-limitation
  • nitrogen
  • northern hardwoods
  • nutrient fertilization
  • phosphorus
  • Digital Object Identifier (doi)

    Pubmed Id

  • 29205288
  • Start Page

  • 438
  • End Page

  • 449
  • Volume

  • 99
  • Issue

  • 2