Exploitation Ecosystems in Gradients of Primary Productivity

  title={Exploitation Ecosystems in Gradients of Primary Productivity},
  author={Lauri Oksanen and Stephen D. Fretwell and Joseph A. Arruda and Pekka Niemela},
  journal={The American Naturalist},
  pages={240 - 261}
Based on the assumption that each trophic level acts as a single exploitative population, a model relating the trophic structure of ecosystems to their potential primary productivity is developed. According to the model, herbivory pressure should be most severe in relatively unproductive environments. With increased potential productivity, the role of predation in herbivore regulation should become more important and the impact of herbivory upon plant communities should decrease. In very… 

Evolution of exploitation ecosystems I. Predation, foraging ecology and population dynamics in herbivores

  • L. Oksanen
  • Environmental Science
    Evolutionary Ecology
  • 2005
SummaryThe hypothesis of exploitation ecosystems was reanalysed using the model of Armstrong (1979) which simultaneously deals with population dynamics and evolution. The results indicate that the

Herbivory and Trophic Interactions

Asymmetry in community regulation: effects of predators and productivity.

It is found that herbivore biomass declines and plant biomass increases in the presence of predators, regardless of system productivity, and top-down effects of predation are transferred through more trophic levels than are bottom-up effects of eutrophication, showing strong asymmetry in the direction of control of biomass distribution in communities.

Resource Edibility and the Effects of Predators and Productivity on the Outcome of Trophic Interactions

A simple model is used to examine interactions among consumers and two types of resources that differ in edibility to predict the abundances of all three populations and confirms that the effects of predators and nutrients on consumers and resources predicted by the model differ when the consumer assemblage is dominated by a generalist herbivore.

Patterns in the abundance of kangaroo populations in arid Australia are consistent with the exploitation ecosystems hypothesis

Findings provide evidence that top–down regulation can prevail over bottom–up regulation of herbivore populations in arid ecosystems and highlights the usefulness of the EEH as a predictor of macro-ecological patterns of species abundance.

Primary productivity and trophic dynamics investigated in a North Derbyshire, UK, dale

Investigation ofrophic interactions on herbaceous communities in a limestone dale in Northern England concluded that herbivore pressure is high because productivity is insufficient to sustain a high intensity of 'top-down' control from carnivores.

Large‐scale responses of herbivore prey to canid predators and primary productivity

This study shows that the EEH has wide application to canid-predator–herbivore dynamics and may be relevant to the management of herbivores because it can provide an indication of how herbivore biomass and densities may vary in relation to ecosystem productivity and the presence and absence of canid predators.

Productivity, organism size, and the trophic structure of the major terrestrial biomes

  • Y. Ayal
  • Environmental Science
    Theoretical Ecology
  • 2010
It is suggested that terrestrial biomes' productivity determines the size of the major organisms and plant physiognomy in them and consequently determines their trophic structure and that productivity is the limiting factor for the number oftrophic levels at the lower end of the terrestrial productivity gradient.

Relative strengths of benthic algal nutrient and grazer limitation along a lake productivity gradient

Nutrient limitation was significantly stronger than grazer limitation across lakes, which was more consistent with the food-web versus food-chain model and the consideration of key species’ traits when predicting and interpreting patterns.

Strong and weak trophic cascades along a productivity gradient

In in situ exclosure experiments, it is found that predator effects were strong and cascaded to plants in a low productivity pond and in an intermediate productivity pond dominated by small herbivore species, and in a high productivity pond, where predator effects on prey biomass were weak, and did not cascade to plants.



A Consideration of Trophic Dynamics in Some Tallgrass Prairie Farm Ponds

Data from five tall-grass prairie farm ponds show that the biomasses of trophic level consumer groups seem to vary systematically with the primary productivity of the ponds and with each other in a manner indicative of predator-prey pairings, corroborate Fretwell (1977) construct that some ecosystem patterns may be explained by the interactions between primary productivity and pr?dation.

Exploitation in Three Trophic Levels

The population dynamics of a general three-species, three-trophic-level exploitational system are explored and removal of carnivores is a perilous ecological gamble.

Paradox of Enrichment: Destabilization of Exploitation Ecosystems in Ecological Time

Man must be very careful in attempting to enrich an ecosystem in order to increase its food yield, because there is a real chance that such activity may result in decimation of the food species that are wanted in greater abundance.

The Regulation of Plant Communities by the Food Chains Exploiting Them

In 1960, three ecologists at the University of Michigan proposed a "balance of nature" hypothesis, which concluded that the predators, as a group, were limited in abundance by the amount of food they could find and capture.

Regulation in Terrestrial Ecosystems, and the Implied Balance of Nature

This rebuttal will demonstrate the internal inconsistency of the criticism of Ehrlich and Birch, clarify some of the considerations raised by Murdoch, and demonstrate in part the empirical validity of the authors' earlier conclusions.


This article is the first attempt to publish the results of the research period (1949-1975) comprehensively and considers that the larch bud moth, Zeiraphera diniana, would meet the criteria for being such a model insect.

The "Balance of Nature" and "Population Control"

The thesis of Hairston, Smith, and Slobodkin that populations of producers, carnivores, and decomposers are limited by their respective resources in the classical density-dependent fashion is based on a series of assumptions about these trophic levels which are, in all probability, false.

How To Be a Predator

This paper discusses what would appear to be the optimal strategy of a predator given two alternative objectives: (1) maximum yield commensurate with the long-term maintenance of the prey species,

Community Structure, Population Control, and Competition

Populations of producers, carnivores, and decomposers are limited by their respective resources in the classical density-dependent fashion and interspecific competition must necessarily exist among the members of each of these three trophic levels.


Measurements were taken in 15 communities along the elevation gradient from fir forest at high elevations, through pine forest, woodlands, and desert grassland, to deserts at low elevations in the