For a species to survive and thrive in a given environment, it not only needs to replace itself but also all the other species around it. So, if one species completely replaces another species, the result is a single dominant species, a monoculture (source 2). According to Gause's law, each species in a given environment occupies different niches for survival. Therefore, two separate species competing for similar resources cannot fundamentally coexist (source Gause). This is known as the competitive exclusion principle. By comparing animal niches with those of various autotrophic plants, one can easily differentiate appropriate ecological niches for animal species simply on the basis of dietary needs (PJ Grubb). In contrast, many autotrophic plants contradict the competitive exclusion principle by sharing similar ecological niches such as sunlight, carbon dioxide, water, and similar mineral nutrients (pj grubb). Many old-growth forests in Michigan's northern Lower Peninsula landscape contain a mixture of tree species rather than a monoculture. Many researchers have put forward ideas to explain the competition and coexistence of tree species in such communities. One theory that explains competition and coexistence between two species is gap regeneration. Gap regeneration occurs when a gap is created upon the death of a plant individual and a new individual, sometimes of the same dead species and sometimes not dependent on environmental heterogeneity, takes its place (Kenneth Lertzman). Canopy gaps during gap regeneration can be explained by both mutual replacement and habitat preference. In a reciprocal substitution, seedlings of one species would be found predominantly under large trees... in the center of the paper... the number would be greater than that of the American beech because the sugar maple produces more seeds than the American beech. Furthermore, we study whether the two species coexist by mutual replacement, habitat preference or simply by chance. We believe that habitat preference may be the coexistence mechanism here and therefore hypothesize that there will be more American beech neighbors as they may account for the majority of the biomass under our third hypothesis. Subsequently, in American beech, root germination is effective in giving them greater horizontal growth than in sugar maple. Thus, we hypothesize that sugar maple canopies will be less asymmetrical than American beech canopies. Finally, because a nearby canopy can limit a tree's canopy growth in the same direction, we hypothesize that a tree will grow its respective canopy away from the nearby canopy to receive maximum sunlight..