Abstract Title

Great grey destructors: how much damage do elephants cause to marula trees and mountain aloes?

Abstract

Elephants are known for being major ecosystem engineers due to their extensive eating habits. We compared adjacent areas with and without elephants in order to assess damage to marula trees (Sclerocarya birrea) and mountain aloes (Aloe marlothii). We hypothesized that plants where elephants are present (Thornybush Game Reserve) would have more damage than plants in areas without elephants (Wits Rural Facility). Marula trees will be shorter, with smaller trunk diameter and higher browse line. Mountain aloes will be shorter and have shorter leaf lengths. We measured marula tree height, trunk diameter and browse height as well as mountain aloe height and leaf length in areas with and without elephants. Because we found no living aloes inside Thornybush Game Reserve, we measured mountain aloes that were located along an adjacent fence line where elephants broke in due to a drought about two years before our study. We also compared the densities of aloes (both dead/de-crowned and alive) in areas with and without elephants present. Our results indicate that the mountain aloes were highly affected by elephant presence because we found no live aloes in the area with elephants. However, we found that the live aloes in the area where elephants had previously broken in were taller with longer leaf lengths (leaf length p-value= 0.0406, height p-value= 0.0002). We also found that the parameters measured regarding the marula trees were not statistically different.

Modified Abstract

We compared responses of marula trees (Sclerocarya birrea) and mountain aloes (Aloe marlothii) between areas with and without elephants, and in and an area where elephants had previously broken in. We hypothesized that marulas would be shorter, with smaller trunk diameter and higher browse height, while the aloes would be shorter and have shorter leaf length in areas with elephants present. We found no live aloes in the area with elephants present, but the aloes near the elephant break in were taller with longer leaf length, on average. Marula trees were not statistically different in the parameters we measured.

Research Category

Biology/Ecology

Primary Author's Major

Zoology

Mentor #1 Information

David

Ward

Start Date

April 2019

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Apr 9th, 1:00 PM

Great grey destructors: how much damage do elephants cause to marula trees and mountain aloes?

Elephants are known for being major ecosystem engineers due to their extensive eating habits. We compared adjacent areas with and without elephants in order to assess damage to marula trees (Sclerocarya birrea) and mountain aloes (Aloe marlothii). We hypothesized that plants where elephants are present (Thornybush Game Reserve) would have more damage than plants in areas without elephants (Wits Rural Facility). Marula trees will be shorter, with smaller trunk diameter and higher browse line. Mountain aloes will be shorter and have shorter leaf lengths. We measured marula tree height, trunk diameter and browse height as well as mountain aloe height and leaf length in areas with and without elephants. Because we found no living aloes inside Thornybush Game Reserve, we measured mountain aloes that were located along an adjacent fence line where elephants broke in due to a drought about two years before our study. We also compared the densities of aloes (both dead/de-crowned and alive) in areas with and without elephants present. Our results indicate that the mountain aloes were highly affected by elephant presence because we found no live aloes in the area with elephants. However, we found that the live aloes in the area where elephants had previously broken in were taller with longer leaf lengths (leaf length p-value= 0.0406, height p-value= 0.0002). We also found that the parameters measured regarding the marula trees were not statistically different.