Untangling interactions: do temperature and habitat fragmentation gradients simultaneously impact biotic...

Area of Science:

• Ecology
• Environmental Science
• Conservation Biology

Background:

• Anthropogenic change impacts ecosystems through multiple drivers acting simultaneously.
• Few studies assess the combined effects of global change drivers across trophic levels.
• Understanding these interactions is crucial for predicting ecological responses.

Purpose of the Study:

• To investigate the interactive effects of climate and habitat fragmentation on a New Zealand tri-trophic food chain.
• To examine differential impacts on species density and biotic processes at each trophic level.
• To determine if drivers act additively or non-additively across the food chain.

Main Methods:

• Utilized temperature gradients as a surrogate for climate variation.
• Quantified habitat fragmentation by fragment area and distance to edges.
• Assessed impacts on plant, herbivore, and natural enemy densities and interactions.
• Measured herbivory and parasitoid attack rates as key biotic processes.

Main Results:

• Drivers acted non-additively across trophic levels.
• Synergistic interactions between location and fragmentation exacerbated negative effects on consumer density.
• Antagonistic interactions ameliorated impacts on plant density and trophic interactions.
• Differential effects observed on species density versus ecological processes.

Conclusions:

• Ecological consequences of multiple global change drivers are strongly interactive.
• Interactions vary significantly by trophic level and measured response (density vs. process).
• Findings highlight the complexity of predicting ecosystem responses to global change.