Megafaunal influences on tree recruitment in African equatorial forests
The forests of central Africa are distinct from counterpart forests in Amazonia by having fewer trees ≥ 10 cm dbh ha-1, especially small trees < 20 cm dbh, and in having sapling cohorts with less diversity than canopy trees. We tested four hypotheses to investigate whether herbivory, in particular, browsing by forest elephants, could be a factor in these differences. We found that the density of small saplings and diversity of large saplings were inversely associated with local density of elephants. We then tested the hypothesis that steep slopes might serve as refugia from elephant foraging, but found that elephants routinely forage on slopes with an inclination of less than ca 30 deg. Nevertheless, the diversity of small trees (≥ 10 cm, < 20 cm dbh) was higher on slopes than on paired level-ground sites. The incidence of break scars on saplings ≥ 2 cm dbh and < 6 cm dbh was greater (107/100 stems) on level ground than on slopes (77/100 stems), although high variability precluded statistical significance. After correcting for background breakage not caused by elephants, an estimated 71% of breaks on level ground and 43% of breaks on slopes were attributable to elephants. Liana loads borne by trees at different sites were highly variable and unrelated to slope. Apparently, disturbances are more critical to liana development than herbivory. Elephants, along with other large mammals such as gorillas, duikers, red river hogs and rodents, appear to act as powerful filters on the tree recruitment process in African forests that still retain intact megafaunal communities.
Duke Scholars
Altmetric Attention Stats
Dimensions Citation Stats
Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Ecology
- 4104 Environmental management
- 4102 Ecological applications
- 3103 Ecology
- 0602 Ecology
- 0502 Environmental Science and Management
- 0501 Ecological Applications
Citation
Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Ecology
- 4104 Environmental management
- 4102 Ecological applications
- 3103 Ecology
- 0602 Ecology
- 0502 Environmental Science and Management
- 0501 Ecological Applications