<P> In the simplest scheme , the first trophic level ( level 1 ) is plants , then herbivores ( level 2 ) , and then carnivores ( level 3 ) . The trophic level is equal to one more than the chain length , which is the number of links connecting to the base . The base of the food chain ( primary producers or detritivores ) is set at zero . Ecologists identify feeding relations and organize species into trophic species through extensive gut content analysis of different species . The technique has been improved through the use of stable isotopes to better trace energy flow through the web . It was once thought that omnivory was rare , but recent evidence suggests otherwise . This realization has made trophic classifications more complex . </P>
<P> In the simplest scheme , the first trophic level ( level 1 ) is plants , then herbivores ( level 2 ) , and then carnivores ( level 3 ) . The trophic level is equal to one more than the chain length , which is the number of links connecting to the base . The base of the food chain ( primary producers or detritivores ) is set at zero . Ecologists identify feeding relations and organize species into trophic species through extensive gut content analysis of different species . The technique has been improved through the use of stable isotopes to better trace energy flow through the web . It was once thought that omnivory was rare , but recent evidence suggests otherwise . This realization has made trophic classifications more complex . </P>
where are producers located on the food chain
where are producers located on the food chain
The base
The base