Ecosystems

, Volume 17, Issue 1, pp 82–95

Effect of Native Vegetation Loss on Stream Ecosystem Processes: Dissolved Organic Matter Composition and Export in Agricultural Landscapes

  • Darren P. Giling
  • Michael R. Grace
  • James R. Thomson
  • Ralph Mac Nally
  • Ross M. Thompson
Article

DOI: 10.1007/s10021-013-9708-6

Cite this article as:
Giling, D.P., Grace, M.R., Thomson, J.R. et al. Ecosystems (2014) 17: 82. doi:10.1007/s10021-013-9708-6

Abstract

Stream and river ecosystems are dependent on energetic inputs from their watersheds and thus shifts in land use from forest cover to agriculture will affect stream community composition and function. The disruption of forest-aquatic linkages alters the organic matter resources in agricultural streams. Dissolved organic matter (DOM) is the dominant form of organic matter in aquatic ecosystems, and a microbial energy source that is important for stream respiration. The concentrations and characteristics of DOM are regulated by both terrestrial (for example, terrestrial organic matter supply) and in-stream processes (for example, microbial respiration and periphyton production) that are influenced by land management. The effects of watershed land use and topographic, soil and climatic variables on DOM quantity (dissolved organic carbon concentration and load), source (terrestrial or in-stream) and quality (composition and lability) were measured in 14 streams across an agricultural land-use gradient. DOC concentration was positively correlated with watershed pasture cover and negatively correlated with watershed relief. No watershed variables were important correlates of DOC load. Stream DOM was primarily of terrestrial origin, but DOM in agricultural streams had a greater proportion of sources from in-stream sources. This may be due to reduced connection with riparian vegetation and increased in-stream primary production. We suggest that maintaining watershed tree cover greater than 52% and ensuring less than 10% of the length of riparian corridor is cleared for pasture could minimize changes to DOM composition. This is important to avoid flow-on effects for stream ecosystem processes that are mediated by DOM. Long-term DOM monitoring will be valuable for assessing the functional impacts of land-use change.

Keywords

agriculture bioavailability DOC DOM microbe pasture riparian vegetation watershed land use 

Supplementary material

10021_2013_9708_MOESM1_ESM.doc (74 kb)
Supplementary material 1 (DOC 74 kb)

Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  • Darren P. Giling
    • 1
  • Michael R. Grace
    • 2
  • James R. Thomson
    • 1
  • Ralph Mac Nally
    • 1
  • Ross M. Thompson
    • 1
    • 3
  1. 1.School of Biological SciencesMonash UniversityMelbourneAustralia
  2. 2.Water Studies Centre, School of ChemistryMonash UniversityMelbourneAustralia
  3. 3.Institute for Applied EcologyUniversity of CanberraCanberraAustralia

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