Intensive grassland management disrupts below-ground multi-trophic resource transfer in response to drought

Area of Science:

• Ecology
• Soil Science
• Environmental Science

Background:

• Land management practices can alter soil food web dynamics, potentially influencing ecosystem resilience to climate extremes.
• Understanding the mechanisms by which soil food webs respond to climate variability and management is crucial for predicting ecosystem functions.
• Limited empirical evidence exists on how grassland management modifies ecosystem process responses to climate extremes.

Purpose of the Study:

• To quantify the impact of grassland management on the transfer of recent photosynthates and soil nitrogen.
• To investigate the role of soil food webs in mediating ecosystem responses to drought legacies.
• To elucidate the mechanisms linking land management, climate extremes, and carbon cycling in grasslands.

Main Methods:

• Utilized in situ carbon-13 (¹³C) and nitrogen-15 (¹⁵N) pulse-labeling in a controlled field experiment.
• Compared intensively and extensively managed grassland sites to assess management effects.
• Monitored the transfer of photosynthates and nitrogen through plants, soil food webs, and soil respiration during a post-drought period.

Main Results:

• Intensive grassland management significantly decreased plant carbon capture and its subsequent transfer through food webs and soil respiration compared to extensive management.
• A notable legacy effect of drought was observed, particularly in intensively managed grasslands.
• Drought legacy increased plant carbon assimilation and ¹³C in soil CO₂ efflux but reduced ¹³C transfer to roots, bacteria, and Collembola in intensively managed systems.

Conclusions:

• Grassland management practices interact with drought effects to influence carbon transfer pathways.
• The capture and rapid transfer of photosynthates via multi-trophic networks are critical for grassland resilience to drought.
• Understanding these complex interactions is essential for developing sustainable grassland management strategies under changing climate conditions.