Consequences of climate-induced range expansions on multiple ecosystem functions

Area of Science:

• Ecology
• Climate Change Biology
• Freshwater Ecology

Background:

• Climate-driven species range shifts are altering ecological communities globally.
• The functional consequences of these shifts on ecosystem processes remain largely unquantified.
• Understanding these changes is crucial for predicting ecosystem stability.

Purpose of the Study:

• To investigate how upslope range expansions of caddisfly species affect their functional roles in nutrient cycling and detritus processing.
• To determine if changes in species composition precede changes in ecosystem function.
• To assess the stability of ecosystem processes despite altered species contributions.

Main Methods:

• A 30-year survey of subalpine pond larval caddisfly assemblages was combined with species-specific functional traits.
• Functional traits included nitrogen and phosphorus excretion and detritus processing rates.
• Relative contributions of species to ecosystem processes were analyzed across three upslope range expansions.

Main Results:

• A subdominant resident species consistently regulated nitrogen supply, irrespective of range expansions.
• Phosphorus supply and detritus processing roles shifted from a dominant resident to an expanding species.
• Despite altered species contributions, total ecosystem process rates remained stable throughout range expansions.

Conclusions:

• Shifts in species' relative functional roles can occur before changes in total ecosystem process rates.
• Altered species functional roles may stabilize ecosystem processes in changing environments.
• This highlights the importance of trait-based approaches in understanding climate change impacts on ecosystems.