Large, old trees provide many important ecosystem services and economic benefits but are generally in decline. Decline is evident in the bushveld savanna ecosystem of South Africa. Decline in populations of marula trees (Sclerocarya birrea) is characterized by increased mortality in mature trees and a lack of recruitment of seedlings. Mortality has been attributed to fire and elephants. In other ecosystems, rodents are known to impact diversity and abundance of plant communities. This research set out to answer two questions. Do bushveld savanna rodents facultatively eat the seeds of selected indigenous tree species? Do these rodents facultatively eat the seedlings of indigenous trees? Investigating these questions may help develop management strategies pertaining to native tree species, especially marula trees.
Rodents were captured and put through feeding trials with the seeds and seedlings of four species of native trees March-August 2016 at Balule Nature Reserve in the greater Kruger ecosystem: marula, false marula (Lannea schweinfurthii), jackalberry (Diospyros mespiloformes), and knobthorn acacia (Acacia nigrescens).
Results/Conclusions
Ninety-nine individuals of five species of rodents were captured over ca. 4282 trap nights. Twenty-four seed damage trials (of all selected species’ seeds) were done with Namaqua rock mice (Micaelamys namaquensis), twelve with red veld rats (Aethomas chrysophilus), two with bushveld gerbils (Tatera leucogaster), two with multimammate mice (Mastomys natalensis), and two with unidentified individuals thought to be Dendromus spp. Thirty-three feeding trials were run with marula seedlings. Twenty-four of these trials were with Namaqua rock mice, four with red veld rats, two with bushveld gerbils, two with Dendromus, and one with a multimammate mouse. Twenty-one trials were run with knobthorn acacia seedlings. Of these 21 trials, 19 were with rock mice and two were with red veld rats. Sixteen trials were completed with false marula seedlings. Of these, 12 were completed with rock mice, three with multimammate mice, and one with a red veld rat. Nine trials were run with jackalberry seedlings. Of these, eight were completed with rock mice and one with a red veld rat. Rodents did facultatively consume the seeds and seedling of the selected indigenous trees. Preferences among seeds (P<0.001 , Fisher’s Exact, df=4 ) and seedlings (P= 0.005, Fisher’s Exact, df=4 ) were present. Our results suggest rodents may be important for structuring savanna plant communities.