Secondary succession: A survey of plant species composition, richness, abundance, and diversity in the University of Michigan burn plots in northern lower Michigan.

Abstract

Ecological succession is a defined sequence of communities that appear after a disturbance has occurred (Chendler et al. 1983). Secondary succession occurs when an existing community is disturbed by fire, flood, parasitic disease, or human agriculture. Our objective was to determine patterns in community composition, richness, abundance, and diversity in patches of a northern lower Michigan pine-hardwood forest that had been clearcut and burned in 1911, 1948, and 1980. The study was conducted at the University of Michigan burn plots located in northern lower Michigan. To identify the woody and herbaceous species, we constructed three parallel transects 5m apart on a north/south compass heading in the 1911, 1948, and 1980 burn plots. We counted and identified all plants within a 1 m2 area every 3m on the east side of each transect. We identified 18 different species of plants for a total of 4229 plants. Woody species composition changed over time due to light-intolerant species such as Populus spp. being crowded out by longer-lived species such as Quercus rubrum. Composition of herbaceous layer changed presumably due to competition for light and nutrients. The abundance of herbaceous species decreased due to the increased woody species forming a canopy that blocked out essential light. Species richness increased in the early stages of succession due to greater availability of nutrients and light. As nutrients and light availability decreased the species richness levels off and then decreased due to species poor competitive abilities. Species diversity varied slightly thru time. This was due to an equal amount of recruitment and elimination as the observed area is shaped by competition for space, light, and nutrients.