Brys, Shefferson, and Jacquemyn 2011

		Brys, R., R.P. Shefferson, and H. Jacquemyn. 2011. Impact of intrinsic and
		extrinsic variables on flowering and reproductive allocation patterns in a perennial iteroparous grassland herb: a ten-year experiment. Oecologia 166: 293-303.

Abstract Herbivores can have strong deleterious effects on plant growth,
reproduction, and even survival. Because these effects might be strongly interrelated,
the direct consumptive effects of herbivores and a variety of indirect effects are difficult
to untangle. Reductions in growth, for example, may strongly impact the flowering
behaviour of plant species in the current season, but at the same time incur costs to
survival, growth and reproduction in the next growing season(s). To get better insights
in the effects of herbivory on the flowering behaviour of the long-lived polycarpic
grassland herb Primula veris L., flowering patterns were monitored over ten
consecutive years under two treatments (grazing and control mowing regimes). We
tested the hypothesis that the size at flowering was affected by the presence of
herbivores, and whether this translated into costs to future reproduction and survival.
Overall, grazed plants were significantly smaller than control plants, and the size at
which plants flowered was also significantly smaller when herbivores were present.
The transition probability of flowering and of surviving into the next year was
significantly smaller for all plants in the current year if they had been grazed than if
they had been mown, indicating that herbivory incurred costs to both flowering and
survival. Grazed plants also needed longer to start flowering, had fewer flowers and
flowered less frequently, causing a significantly lower proportion of flowering adults in
the population. These results suggest that the observed regression in plant size due
to herbivory does not allow plants to capture enough resources to guarantee regular
flowering in the longer run.

Brys, Shefferson, and Jacquemyn
2011