Ecosystems

pp 1–15

Climate, Topography, and Canopy Chemistry Exert Hierarchical Control Over Soil N Cycling in a Neotropical Lowland Forest

  • Brooke B. Osborne
  • Megan K. Nasto
  • Gregory P. Asner
  • Christopher S. Balzotti
  • Cory C. Cleveland
  • Benjamin W. Sullivan
  • Philip G. Taylor
  • Alan R. Townsend
  • Stephen Porder
Article

DOI: 10.1007/s10021-016-0095-7

Cite this article as:
Osborne, B.B., Nasto, M.K., Asner, G.P. et al. Ecosystems (2017). doi:10.1007/s10021-016-0095-7

Abstract

Nutrient availability varies substantially across lowland tropical forests and constrains their responses to global change. However, interactions among regional, landscape, and local controls of nutrient availability are poorly understood. In that context, we explored the effects of rainfall, topography, and canopy chemistry on nitrogen (N) cycling across the Osa Peninsula (Costa Rica). We sampled soils from catenas in regions receiving 3000 versus 5000 mm y−1 rainfall. In both regions, we sampled catenas starting on narrow, knife-edged ridges, and in the less humid region we compared catenas starting on rapidly eroding knife-edged ridges to catenas with ridges consisting of slowly eroding terraces. On the stable terraces, we sampled soils from 0.25 ha plots with either high or low mean canopy N. In all sites, we measured metrics of long- (soil δ15N) and short-term (net nitrification, net N mineralization, and KCl-extractable N) N availability. Mean soil δ15N was elevated in the less humid region (3.8 ± 0.16 vs. 3.1 ± 0.14‰; P = 0.003). Within that region, mean δ15N was enriched by approximately 1‰ on stable terraces (5.3 ± 0.14‰) relative to nearby knife-edged ridges (4.0 ± 0.24‰; P < 0.001). Short-term N metrics did not vary with rainfall or topography (P > 0.05). By contrast, short-term soil N metrics differed under canopies with high versus low canopy N, but soil δ15N did not. These results illustrate the role of climate and topography as dominant drivers of long-term N cycling in the region, as well as the potential for canopy characteristics, which are likely determined by species composition in this system, to impose small-scale heterogeneity within those broader constraints. Overall, our work suggests the utility of a hierarchical framework for understanding how diverse drivers of nutrient status interact across space and time in tropical forests.

Keywords

15canopy chemistry Carnegie Airborne Observatory climate imaging spectroscopy LiDAR nitrogen soil topography 

Supplementary material

10021_2016_95_MOESM1_ESM.docx (14 kb)
Supplementary material 1 (DOCX 14 kb)
10021_2016_95_MOESM2_ESM.jpg (227 kb)
Supplementary material 2 (JPEG 226 kb)
10021_2016_95_MOESM3_ESM.jpg (83 kb)
Supplementary material 3 (JPEG 83 kb)

Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  • Brooke B. Osborne
    • 1
  • Megan K. Nasto
    • 2
  • Gregory P. Asner
    • 3
  • Christopher S. Balzotti
    • 3
  • Cory C. Cleveland
    • 2
  • Benjamin W. Sullivan
    • 4
  • Philip G. Taylor
    • 5
  • Alan R. Townsend
    • 5
  • Stephen Porder
    • 1
  1. 1.Department of Ecology and Evolutionary Biology, Institute at Brown for Environment and SocietyBrown UniversityProvidenceUSA
  2. 2.Department of Ecosystem and Conservation ScienceUniversity of MontanaMissoulaUSA
  3. 3.Department of Global EcologyCarnegie Institution for ScienceStanfordUSA
  4. 4.Department of Natural Resources and Environmental ScienceUniversity of NevadaRenoUSA
  5. 5.Nicholas School of the EnvironmentDuke UniversityDurhamUSA