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Vegetation structure modulates ecosystem and community responses to spatial subsidies
  • Matthew McCary,
  • Randy Jackson,
  • Claudio Gratton
Matthew McCary
University of Wisconsin-Madison
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Randy Jackson
University of Wisconsin-Madison
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Claudio Gratton
University of Wisconsin-Madison
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Abstract

Ecosystem responses to external inputs of nutrients and organisms are highly variable. Theory predicts that ecosystem traits will determine the responses to resource subsidies, but evidence for how vegetation structure can modulate those effects is lacking. We tested how plant height influenced subsidy effects by cutting vegetation and reducing insect subsidies in a subarctic grassland over two years. We found that taller canopies intercepted more insect subsidies than shorter ones, leading to faster litter decomposition in tall vegetation with available subsidies. Arthropod composition also shifted due to limited access to subsidies in shorter vegetation. Our findings indicate that vegetation structure can modify the quantity of subsidies entering a recipient ecosystem as aerial insects, resulting in ecosystem- and community-level responses. Thus, changing vegetation structure via habitat disturbances could fundamentally alter ecosystem functions that depend on spatial subsidies.