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Marula Sclerocarya birrea subsp. caffra dispersal by mammals: are squirrels seed predators or seed dispersers?
| Content Provider | Semantic Scholar |
|---|---|
| Author | Gallaher, Kirsten |
| Copyright Year | 2010 |
| Abstract | The marula (Sclerocarya birrea subsp. caffra) is a well known dioecious tree found across much of central and southern Africa. Dispersal mechanisms for marulas are still unclear, although it is known that endozoochory, especially by elephants, plays an important role by increasing the percentage germination of the seeds. The tree squirrel (Paraxerus cepapi subsp. cepapi) has been observed removing marulas from elephant dung, and there are a few observations of them scatterhoarding seeds. The goals of this study were: 1) to determine if tree squirrels scatterhoard marula seeds, 2) to examine natural predation rates of stones under adult trees, and 3) to investigate whether the possible dispersal relationship is visible in density and demographic signals across the landscape. To accomplish this, we performed cafeteria experiments and surveyed marula populations and seed predation inside and outside large herbivore exclusion plots at N'waxitshumbe, Shingwedzi, Skuku / and Pretoriuskop in the Kruger National Park, South Africa. Our findings confirmed that squirrels do scatterhoard and disperse marulas. They were observed burying 46% of marula stones (n = 50). The average burial depth was 0.53cm (±0.3 1; n = 15) and mean dispersal distance 4.57m (±6.81; n = 33). Predation rates of marulas under adult trees were lower than expected: between 30 and 56% of stones lying on the surface were not predated at all). Patterns of marula demography and distribution across the landscape varied greatly between sites, which is likely to be related to different fire regimes, herbivore densities and climates. It was, however, evident that scatter-hoarding could be an important dispersal mechanism for the marula, and could be the second phase of a diplochorous seed-dispersal relationship with elephants. Un ive rsi ty of Ca pe To wn |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://open.uct.ac.za/bitstream/handle/11427/26129/von_Hase_Can_soil_factors_Namibian_2010_1.pdf?isAllowed=y&sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
