Oecologia

, Volume 160, Issue 4, pp 757–770

Placing biodiversity and ecosystem functioning in context: environmental perturbations and the effects of species richness in a stream field experiment

  • Brendan G. McKie
  • Markus Schindler
  • Mark O. Gessner
  • Björn Malmqvist
Community ecology - Original Paper

DOI: 10.1007/s00442-009-1336-7

Cite this article as:
McKie, B.G., Schindler, M., Gessner, M.O. et al. Oecologia (2009) 160: 757. doi:10.1007/s00442-009-1336-7

Abstract

Greater biodiversity is often associated with increased ecosystem process rates, and is expected to enhance the stability of ecosystem functioning under abiotic stress. However, these relationships might themselves be altered by environmental factors, complicating prediction of the effects of species loss in ecosystems subjected to abiotic stress. In boreal streams, we investigated effects of biodiversity and two abiotic perturbations on three related indices of ecosystem functioning: leaf decomposition, detritivore leaf processing efficiency (LPE) and detritivore growth. Replicate field enclosures containing leaves and detritivore assemblages were exposed to liming and nutrient enrichment, raising pH and nutrient levels. Both treatments constitute perturbations for our naturally acidic and nutrient-poor streams. We also varied detritivore species richness and density. The effects of the abiotic and diversity manipulations were similar in magnitude, but whereas leaf decomposition increased by 18% and 8% following liming and nutrient enrichment, respectively, increased detritivore richness reduced leaf decomposition (6%), detritivore LPE (19%) and detritivore growth (12%). The detritivore richness effect on growth was associated with negative trait-independent complementarity, indicating interspecific interference competition. These interactions were apparently alleviated in both enriched and limed enclosures, as trait-independent complementarity became less negative. LPE increased with detritivore density in the monocultures, indicating benefits of intra-specific aggregation that outweighed the costs of intra-specific competition, and dilution of these benefits probably contributed to lowered leaf decomposition in the species mixtures. Finally, the effects of liming were reduced in most species mixtures relative to the monocultures. These results demonstrate how environmental changes might regulate the consequences of species loss for functioning in anthropogenically perturbed ecosystems, and highlight potential influences of biodiversity on functional stability. Additionally, the negative effects of richness and positive effects of density in our field study were opposite to previous laboratory observations, further illustrating the importance of environmental context for biodiversity–ecosystem functioning relationships.

Keywords

Density dependenceDiversity–stabilityIntra-specific aggregationMultiple stressorsStatistical averaging

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Brendan G. McKie
    • 1
    • 3
  • Markus Schindler
    • 2
  • Mark O. Gessner
    • 2
  • Björn Malmqvist
    • 1
  1. 1.Department of Ecology and Environmental ScienceUmeå UniversityUmeåSweden
  2. 2.Department of Aquatic EcologyEAWAG, Swiss Federal Institute of Aquatic Science and Technology, and Institute of Integrative Biology (IBZ), ETH ZurichKastanienbaumSwitzerland
  3. 3.Department of Aquatic Sciences and AssessmentSLUUppsalaSweden