Some plants may compensate for herbivore damage by stimulating nutrient release in the soil

Browsing by mammals often has a serious impact on the growth of tree saplings and the regeneration of forests. However, there is much uncertainty with regard to effects on soil nutrient cycling and in turn, potential consequences for the growth of plants.

In a paper to be published in the June issue of Ecology Letters, researchers from Lancaster University and the Centre for Ecology and Hydrology have demonstrated a direct link between above-ground herbivory and below-ground nutrient cycling. Partial defoliation of tree saplings (European beech and silver fir) stimulated micro-organisms in the soil to release inorganic nitrogen (which is potentially readily available for plant use) at an increased rate.

Beech responded to the increased nitrogen availability by producing larger leaves with a greater photosynthetic capacity, compensating for the initial defoliation. Fir saplings showed no such compensatory responses, and growth was dramatically reduced. Such processes could potentially alter the ability of trees to tolerate herbivory and may also influence the competitive balance between tree species, particularly in regenerating forests subject to browsing.