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Ecosystems

, Volume 17, Issue 8, pp 1455–1468 | Cite as

Biogeochemical Hotspots in Forested Landscapes: The Role of Vernal Pools in Denitrification and Organic Matter Processing

  • Krista A. Capps
  • Regina Rancatti
  • Nathan Tomczyk
  • Thomas B. Parr
  • Aram J. K. Calhoun
  • Malcolm HunterJr.
Article

Abstract

Quantifying spatial and temporal heterogeneity in ecosystem processes presents a challenge for conserving ecosystem function across landscapes. In particular, many ecosystems contain small features that play larger roles in ecosystem processes than their size would indicate; thus, they may represent “hotspots” of activity relative to their surroundings. Biogeochemical hotspots are characterized as small features within a landscape that show comparatively high chemical reaction rates. In northeastern forests in North America, vernal pools are abundant, small features that typically fill in spring with snow melt and precipitation and dry by the end of summer. Ephemeral flooding alters soil moisture and the depth of the soil’s oxic/anoxic boundary, which may affect biogeochemical processes. We studied the effects of vernal pools on leaf-litter decomposition rates, soil enzyme activity, and denitrification in vernal pools to assess whether they function as biogeochemical hotspots. Our results indicate that seasonal inundation enhanced leaf-litter decomposition, denitrification, and enzyme activity in vernal pools relative to adjacent forest sites. Leaves in seasonally flooded areas decomposed faster than leaves in terra firme forest sites. Flooding also influenced the C, N, and P stoichiometry of decomposing leaf litter and explained the variance in microbial extracellular enzyme activity for phosphatase, β-d-glucosidase, and β-N-acetylglucosaminidase. Additionally, denitrification rates were enhanced by seasonal flooding across all of the study pools. Collectively, these data suggest that vernal pool ecosystems may function as hotspots of leaf-litter decomposition and denitrification and play a significant role in decomposition and nutrient dynamics relative to their size.

Keywords

ephemeral wetland biogeochemical hotspot leaf-litter decomposition denitrification soil enzymes 

Notes

Acknowledgments

We would like to thank Dennis Anderson for help in the lab and Randi Jackson for help in the field. This work was funded by Maine’s Sustainability Solutions Initiative (National Science Foundation Award Number: 0904155). We would also like to thank the subject editor and the anonymous reviewers who provided comments that enhanced the quality of this manuscript.

Supplementary material

10021_2014_9807_MOESM1_ESM.jpg (42 kb)
Supplemental Figure 1 Enzyme activity in soils in each of the three locations in each pool. Dashed lines are the 1:1 ratio. (A) relationship between carbon and nitrogen acquiring activities, (B) relationship between carbon and phosphorus acquiring activities (JPEG 41 kb)

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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Krista A. Capps
    • 1
    • 2
  • Regina Rancatti
    • 3
  • Nathan Tomczyk
    • 3
  • Thomas B. Parr
    • 1
    • 3
  • Aram J. K. Calhoun
    • 1
    • 2
    • 3
  • Malcolm HunterJr.
    • 1
    • 2
  1. 1.Sustainability Solutions InitiativeUniversity of MaineOronoUSA
  2. 2.Department of Wildlife, Fisheries, and Conservation BiologyUniversity of MaineOronoUSA
  3. 3.Ecology and Environmental Science ProgramUniversity of MaineOronoUSA

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