# data[].attributes.body
nutrients (Lawton and McNeill 1979) e.g. nitrogen or hard to digest structures e.g. nitrogen

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bottom up- spatial processes affect accessibility to plants

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bottom up- spatial processes affect accessibility to plants

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plants can hide either
- visually
- olfactory
- with a wide distribution
This reduces the efficiency of finding food = energy loss = energy not adequate to meant survival demands = high density pop can't be maintained

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Microbes can act from a top-down (helping herbivores digest plant matter in the gut) or bottom-up (fungi symbiotic relationship with plants to produce defensive toxins) perspective.

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Something that may apply within one system may not be the same in another - some may be more controlled by top down/bottom up/other processes than other seemingly similar systems

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inter-related feedback loops make it hard to choose top down or bottom up

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inter-related feedback loops make it hard to choose top down or bottom up

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Fire as a herbivore - follows the rules of herbivory

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The world is green because higher trophic levels (predators) control herbivore abundance.

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Herbivores are seldom food-limited, appear most often to be predator-limited, and therefore are not likely to compete for common resources

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most predators would be unable to make any significant impact on the numbers of a prey which is very rare for most of the time, but suddenly becomes very abundant for a few weeks in one season

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Referee for Karhu and Neuvonen (1997) wrote a critical review of the research, showing its contentious even within like-minded research groups.

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A green world doesn't mean an edible one (Power 1992)

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A green world doesn't mean an edible one (Power 1992)

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- herbivory resistant plants e.g. thorny
- foods for herbs present but not being eaten (sheep experiment, Hill et al 1992)

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Any population which is not resource-limited must, of course, be limited to a level below that set by its resources

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In an environment where things consume one another, why don't they eat the thing they consume until there is none left - how do species coexist to form this balance

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Top down control doesn't make the world green/brown

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Top down control doesn't make the world green/brown

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It only changes the distribution/type of vegetation

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evidence for both protecting plants (alkaloid producing fungi that protect grass) and facilitating herbivory (gut microbes to digest cellulose)

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Plants historically viewed as passive, now understood to have active defensive mechanisms.

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(Richards and Coley 2007) review how there is a dual role of bottom-up and top-down in tropical forests in panama

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- Environmental constraints (often climatic) prevent herbs from getting to high enough densities to exploit all greenery
- competition: inter vs intra specific comp keeps herbs in check

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Sounds like a simple question that should have a clear answer, but in reality is very complex.

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Hairston 1960 supports predator top-down control.

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bottom up- plants produce toxic chemicals that dissuade herbivory

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bottom up- plants produce toxic chemicals that dissuade herbivory

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Short term: reduce palatability, encourage herb to move away from the plant and stop eating it
Long term: poison makes plant unable to support high density population as herb can't eat too much of the plant to gain enough energy for efficient reproduction

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top down- excluding sheep from grazing areas changed species composition (Hill et al 1992)

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top down- excluding sheep from grazing areas changed species composition (Hill et al 1992)

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Top down vs bottom up vs sideways vs environmental

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Why is the world green not brown