The study of ecology is currently primarily focused upon anthropogenic effects on ecosystems as well as feeding relationships; however, non-feeding interactions are also an important factor in understanding the balance of the ecosystem and identifying issues. These interactions are generally termed disturbances. What constitutes a disturbance? White and Pickett defined it as “any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the physical environment” (White 1985). Some definitions of disturbances such as Grime's require the destruction of biomass, however, this tends to rule out many events that cause changes in the makeup of ecosystems yet are not feeding interactions (Buckley 1992).
All animals interact with their environment beyond simply feeding as even walking can affect the makeup of the environment by crushing grasses or insects. Still, not all animals have the same degree of effect on the environment - certain animals are considered to be “ecosystem engineers.”
These ecosystem engineers include crocodiles and beavers, animals that substantially change the environment around them to adapt it to their needs. Clive G. Jones defined ecosystem engineers as “organisms that directly or indirectly modulate the availability of resources to other species, by causing physical state changes in biotic or abiotic materials. In doing so, they modify, maintain, and create habitats”(Jones 1994).
Of course, not all organisms that have non-trophic effects on their environment are ecosystem engineers. It is simply that the effects of the ecosystem engineer tend to be the best studied as they have the largest, most deliberate effect. However, other animals may have an equally important impact on the environment.
Harald Beck's 2006 study of peccary-palm interactions, while not set in Eastern deciduous forests, suggests one method of how feeding and non-feeding interactions can combine to impact the environment. In addition to eating seedlings, seeds, and plants, peccaries trample the ground. The combination of the peccaries' trampling of the ground and their expectoration of seeds can increase seeds' survival (Beck 2006). Without the peccaries to trample the area, the seeds face increased competition for resources.
Of course, because the peccaries also trample palm seedlings as well as their competitors, this effect depends on the foraging behavior of the peccary. (Beck 2006) Only peccaries foraging near palms provide a benefit to the palm population - any foraging in palms reduced the seeds and seedlings' survival. Overall, studies conducted in 2003 and 2004 by Wyatt and Silman revealed that the presence of peccaries reduced palm seed survival drastically (Wyatt and Silman 2003, 2004).
Does this conclusion indicate that removing peccaries would aid in conserving the dwindling palm population? Not necessarily – while overall palm survival...