Long-term soil feedback on plant N allocation in defoliated grassland miniecosystems

Defoliation of plants is known to have effects on soil organisms and nutrient availability in grassland communities, but few studies have examined whether changes in soil attributes can further feed back to plant growth and plant nutrient content. To examine defoliation-induced soil feedbacks, we established replicated miniecosystems with a grass Phleum pratense, defoliated half of the systems, collected soil from both defoliated and non-defoliated systems and planted new seedlings into each soil. The two soils did not differ in promoting shoot and root growth. However, seedlings that grew in the soil collected from defoliated systems had higher shoot N content, allocated relatively more N to shoots and had lower root N concentration than those growing in the soil collected from non-defoliated systems. Our study provides novel evidence that defoliation can generate long-lasting changes in grassland soil that in turn can affect plant N allocation.