Oesterheld and McNaughton tested the hypothesis that the amount of compensatory growth after defoliation is affected by the level of stress at which plants grow when defoliated and by the length of time of recovery. Relative growth rate (RGR: new / total biomass) decreases with old/dead tissue accumulation, and therefore increased with defoliation, since the release from litter accumulation overrode the negative effect of biomass loss. Full compensation (by increased RGR) was more likely to occur under stress conditions and overcompensation did not occur under optimal growth conditions (i.e. when stressor is limiting there is no ability to compensate, but when stressor is removed, there is no room for increase in RGR, and response is a linear curve peaking at a point closer to the "stressed" extrema). With a short time for recovery, RGR was decreased by defoliation because an immediate increase in net assimilation rate was overridden by a reduction in the ratio of leaf area to plant weight. After defoliation, this ratio increased quickly due to a larger allocation to leaf growth and lower leaf specific weights, resulting in higher RGR. Briza subaristata was particularly conservative in terms of its allocation to roots and this contrasted with observations for other species. The authors note that this contradicts the conclusion that compensatory growth aboveground in associated to inevitable losses belowground. They conclude that compensatory response to grazing depends on the type and level of stress limiting growth.
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