Ecology lab 4

Hypothesis and predictions The density of saplings in a given area is directly proportional to light availability and inversely proportional to the density of adults. In an area where there are more adults, there is more competition and therefore fewer opportunities for growth of new saplings – which would be out-competed by existing adults. This prediction is based on the ecological maxim, “Space Matters”. Furthermore, since light is necessary for photosynthesis to occur for energy purposes, it follows that individuals would be more abundant where this specific resource is more plentiful. In areas where light availability is scarce, saplings would be less likely to proliferate as one or more adult individuals likely outcompete any others, blocking much light availability from being available to others. This can be summed up by the following predictions: Where there is a greater number of competing adult individuals per area measured, there are fewer saplings.More light availability would correlate to a greater sapling density.Less competition (in terms of space) with adult individuals combined with more light availability would correlate to an even greater sapling density. Methods The area of interest was the Danby woodlot. The researchers randomly selected an adult tree in the woodlot and lay transect tapes such that 6 meter radii were formed around the adult; the species of the adult was recorded. The number of saplings of the same species as the adult was counted, within a 6 meter radius relative to the adult. For Buckthorn, maximum height for saplings was waist length for a 1.61 meter tall female, and for all other species, maximum sapling height was approximately 2 meters. Then, researchers counted the number of competing adults in the same area. For Buckthorn, minimum height for adults was waist length for a 1.61 meter tall female, and for all other species, minimum adult height was approximately 2 meters. The researchers proceeded to estimate the percentage of light penetration (light availability) by making a quadrat with the index fingers and thumbs – at four locations along the 6 meter radius. The experiment was executed a total of 30 times. Researchers looked to confirm a negative correlation between density of competing adults and sapling density, and a positive correlation between sapling density and light availability.