GRAZING OPTIMIZATION AND NUTRIENT CYCLING: WHEN DO HERBIVORES ENHANCE PLANT PRODUCTION?

@article{Mazancourt1998GRAZINGOA,
  title={GRAZING OPTIMIZATION AND NUTRIENT CYCLING: WHEN DO HERBIVORES ENHANCE PLANT PRODUCTION?},
  author={Claire de Mazancourt and Michel Loreau and Luc Abbadie},
  journal={Ecology},
  year={1998},
  volume={79},
  pages={2242-2252}
}
In a general theoretical ecosystem model, we investigate the conditions under which herbivores increase primary production and lead to grazing optimization through recycling of a limiting nutrient. Analytical and simulation studies of the model lead to several general results. Grazing optimization requires that (1) the proportion of nutrient lost along the herbivore pathway be sufficiently smaller than the proportion of nutrient lost throughout the rest of the ecosystem; and that (2) inputs… 

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References

SHOWING 1-10 OF 36 REFERENCES

Physiological Responses of Plant Populations to Herbivory and Their Consequences for Ecosystem Nutrient Flow

TLDR
Differences between the populations provided important controls over nitrogen losses and feedbacks between plant responses to grazing and nitrogen cycling accounted for increased nitrogen availability with grazing, suggesting ecosystem function may be sensitive to physiological differences in population responses to periodic disturbances like herbivory.

Plankton Community Structure and Limnetic Primary Production

A mechanistic, size-structured model was used to analyze effects of grazers on lacustrine primary productivity. Dependence of grazing and nutrient excretion rates on herbivore size, and dependence of

Quantitative Effects of Grazing on Vegetation and Soils Over a Global Range of Environments

TLDR
The data and models support the controversial hypothesis that grazing can increase ANPP in some situations and suggest that grasslands may be inadvertently grazing shrublands more intensively than grasslands, but also suggest that the geographical location where grazing occurs may be more important than how many animals are grazed or how intensively an area is grazing.

Do consumers maximize plant fitness

TLDR
The hypothesis is developed that consumers, like pollinators, have a mutualistic relationship with plants and plants regulate and even encourage a spectrum of consumers whose overall effect is to maximize plant fitness.

A model of herbivore feedback on plant productivity

Grazing as an Optimization Process: Grass-Ungulate Relationships in the Serengeti

TLDR
Experiments in Tanzania's Serengeti National Park showed that net above-ground primary productivity of grasslands was strongly regulated by grazing intensity in wet-season concentration areas of the large ungulate fauna, suggesting that conventional definitions of overgrazing may be inapplicable to these native plant-herbivore systems.

Consumers as Maximizers of Matter and Energy Flow in Ecosystems

  • M. Loreau
  • Environmental Science
    The American Naturalist
  • 1995
TLDR
It is likely that consumers as a whole do generally play a role of maximizers of matter and energy flow in stable natural ecosystems.

Ecology of a Grazing Ecosystem: The Serengeti

TLDR
Great species diversity was associated with greater biomass stability through the seasons, greater resistance to grazing by a single species of ungulate in both the wet and dry seasons, and greater resilience after grazing, and specific properties of trophic web members were identified that produced greater functional stability in more diverse communities.

Grazing and the dynamics of nutrient and energy regulated microbial processes in the Serengeti grasslands

TLDR
The more efficient utilization of dung compared with plant litter, appeared to be related to more balanced C/nutrient ratios ofdung and the energy or nutrient limited site-specific characteristics of microbial growth, on sites of low nutrient availability.

Do Grazers Maximize Individual Plant Fitness

TLDR
It is concluded that the fitness of particularly shortlived plant species is enhanced when grazed by animals wasting extensive amounts of clipped vegetation and/or defecating close to the eaten plant.