Fragmentation and thresholds in hydrological flow-based ecosystem services.

Area of Science:

• Ecology
• Environmental Science
• Hydrology

Background:

• Agricultural expansion causes land cover loss and fragmentation, impacting ecosystem services.
• Hydrological mitigation services, like sediment and nutrient retention, are provided by landscape features that interrupt runoff.
• Woodland position and landscape topography are key factors in hydrological mitigation.

Purpose of the Study:

• To investigate the effects of landscape configuration on hydrological mitigation services.
• To analyze the impact of woodland fragmentation and area on the "mitigated area" within catchments.
• To identify key metrics for predicting the effectiveness of woodland in hydrological mitigation.

Main Methods:

• Generated over 7,000 virtual landscape configurations with varying woodland patch numbers and areas.
• Superimposed virtual landscapes onto real topography and stream networks.
• Utilized an Ecosystem Service model with hydrological routing to map mitigated areas.

Main Results:

• Increased woodland fragmentation led to a greater proportion of the catchment being mitigated.
• Woodland area positively influenced mitigation up to a threshold of 50% coverage, after which benefits declined.
• Edge density was the strongest predictor of mitigated area, while distance to streams was not significant.

Conclusions:

• Woodland fragmentation can enhance hydrological mitigation services.
• Optimal woodland configuration for hydrological services depends on both fragmentation level and existing woodland area.
• Agri-environment schemes should consider fragmentation and edge density, not just riparian planting, for effective hydrological mitigation.