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Tree Seedling Growth

Determining if woody plants show increased growth and nutrient content when grown in soil fertilized by a megacarcass.

Existing research has shown that plant communities at medium-sized carcass sites in North America and Australia are more diverse than other areas. In addition, it is well documented that herbaceous plant growth is stimulated by nutrients from animal carcasses. However, it is unknown whether nutrient pulses from megacarcasses lead to locally increased growth of woody plants in African savannas.

Thus, our question is: Do woody plants show increased growth and nutrient content when grown in soil fertilized by a megacarcass?

We hypothesize that: After a one-year trial, tree seedling growth (total height, diameter at soil height, and total dry mass), leaf dry mass, and nutrient content will all be significantly higher in seedlings grown in megacarcass soil as opposed to regular soil across all five tree species we are testing.

To test this, we collected soil from a megacarcass site (5 m from the center) and a control site 25 m away. We then drove the soil to the Skukuza Indigenous Plant Nursery where we planted 10 replicate seedlings of each of five species of native woody plants (Acacia nigrescens, Acacia tortilis, Combretum hereroense, Sclerocarya birrea, and Terminalia sericea) in each soil type, that is, megacarcass soil and control soil. These seedlings are currently being taken care of by the Skukuza Indigenous Plant Nursery manger, Muerel Baloyi. She and her staff will allow them to grow for a full year before they are harvested for analysis.

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What happens next:

After a full year of growth, all plants will be harvested and measured for total height, canopy height, canopy width, diameter at soil height, above- and belowground biomass, and leaf nutrients. In addition, before the experiment began, we sacrificed 10 replicates of each species and measured their diameter at soil height, general height, and above- and belowground biomass which involved drying and weighing them. We also collected soil samples from each soil type and sent subsamples for standard nutrient analyses (such as Nitrogen, Phosphorus, Potassium). At present, we have our general baseline data (the 10 of each species that were dried and weighed), and the individual heights and diameters of each of seedling in each soil type.

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