Thresholds of functional trait diversity driven by land use intensification

Area of Science:

• Ecology
• Agricultural Science
• Environmental Science

Background:

• Ecosystems face abrupt changes with increasing land use intensification.
• Agricultural grasslands are vital but sensitive to management practices like fertilization and grazing.

Purpose of the Study:

• To assess the impact of land use intensification on grassland functional structure, diversity, and temporal stability.
• To identify critical thresholds of fertilization and grazing intensity that trigger significant ecosystem changes.

Main Methods:

• Analysis of multi-site time series data (2008-2020) from 150 agricultural grasslands.
• Examination of plant trait distributions under varying intensities of fertilization, grazing, and mowing.
• Identification of thresholds in functional structure, diversity, and stability.

Main Results:

• Two critical thresholds for grassland ecosystem change were identified.
• The first threshold distinguished unfertilized from fertilized grasslands, showing trait evenness in extensively managed systems.
• Intensified management (fertilization > 80 kg N/ha/yr or grazing > 500 LUs/ha/yr) led to functionally poor, unstable, and vulnerable grasslands.

Conclusions:

• Intensive management pushes grasslands towards a less diverse and more unstable state.
• Quantified thresholds indicate when grasslands transition from high biodiversity.
• Identified thresholds offer targets for sustainable management and fertilization practices.