Shifting leaf fall phenology disrupts ecosystem function

Area of Science:

• Ecology
• Environmental Science
• Ecosystem Dynamics

Background:

• Leaf litter is a crucial resource subsidy in temperate streams, with seasonal input influencing ecosystem function.
• Climate change is altering leaf senescence phenology, leading to shifts in the timing and order of leaf litter fall.
• The impact of altered subsidy arrival order and duration on ecosystem processes remains poorly understood.

Purpose of the Study:

• To investigate how the order of arrival and exposure duration of different leaf litter subsidies affect ecosystem function.
• To determine the consequences of altered leaf fall phenology on decomposition rates and carbon cycling.

Main Methods:

• A mesocosm experiment was designed to manipulate the arrival order of two contrasting leaf species (high- and low-nutrient).
• Decomposition rates were measured by an abundant aquatic shredder under different subsidy order and duration scenarios.

Main Results:

• Both the exposure duration and arrival order of leaf species significantly influenced the combined consumption of leaf litter.
• The earlier arrival of high-quality (high-nutrient) leaves enhanced the shredder's feeding activity on low-quality (low-nutrient) leaves.
• Shifts in leaf fall timing and order can impact carbon cycling, even if total resource quantity remains unchanged.

Conclusions:

• Altered leaf fall phenology due to climate change can directly affect ecosystem processes like carbon cycling.
• Temporal aspects of resource subsidies, including arrival order and duration, are critical for understanding climate change impacts on ecosystem functioning.
• Further research should incorporate temporal ecological dynamics to predict ecosystem responses to global change.