If the bottom of the food chain became the top Biology Diagrams Top Down vs Bottom Up Control. occurred at either the top trophic level or the bottom trophic level and then impacted the other levels up or down the food chain. In the top-down control, the populations of the organisms lower trophic levels (bottom of the pyramid) are controlled by the organisms at the top. This approach is also called the The bottom-up control. The bottom-up control is driven by the presence or absence of the producers in the ecosystem. Changes in their population will affect the population of all the species in the food web, and thus, the ecosystem. This approach is also called the resource-controlled (or food-limited) food web of an ecosystem. Again, for The question of whether food webs are resource- (bottom-up) or predation- (top-down) controlled is one of the most fundamental research questions in ecology (1-3).Marine ecosystems, originally thought to be mainly steered by bottom-up control, have recently been shown to exhibit periods of top-down control due to the extraction of large predators through fishing (4-7) or climate
FIG. 1. Mechanisms (curved arrows) modulating top-down and bottom-up forces (straight arrows) in food chains. levels (Oksanen et al. 1981, Mittelbach et al. 1988: 220, Fig. 1). Predators may not regulate their food resources ef-ficiently, however, if they fight with each other, are limited by and compete for resources other than food We categorize these directional cascades as top-down or bottom-up control, which simply means the changes to the food chain occurred at either the top trophic level or the bottom trophic level and then impacted the other levels up or down the food chain. A top-down controlled system focuses on how top consumers influence lower trophic levels Following this approach, we propose a general framework for the analysis of bottom-up and top-down forcing of ecosystems by reducing food webs to two energy pathways originating from a limiting resource shared by competing guilds of primary producers (e.g. edible vs. defended plants).
Simple rules describe bottom‐up and top‐down control in food webs with ... Biology Diagrams
Ecosystems are commonly organized into trophic levels-organisms that occupy the same level in a food chain (e.g., plants, herbivores, carnivores). between trophic structure, diversity, and competition shapes the properties of ecosyst … Emergent competition shapes top-down versus bottom-up control in multi-trophic ecosystems PLoS Comput Ecosystems are commonly organized into trophic levels—organisms that occupy the same level in a food chain (e.g., plants, herbivores, carnivores). Möllmann C, Helaouët P, Bayliss-Brown GA, Stenseth NC. Interaction between top-down and bottom-up control in marine food webs. Proceedings of the National Academy of Sciences of the United
