Ficus abutilifolia and Ficus tettensis maturation: location and cracks are crucial factors

Ficus abutilifolia and Ficus tettensis are two species of deciduous rock fig trees commonly found on the vertical faces of Mapungubwe National Park, South Africa. The demographics of the rock figs as well as the habitat features necessary for successful maturation are currently unknown. This study first aims to provide demographic data and determine the points in the fig life cycle where bottlenecks occur. Secondly, it probes the importance to growth of location and usage of cracks. From general observations, we hypothesized that seedlings would be located anywhere on the rock faces, but that larger trees would be more limited to specific areas. We also conjectured that usage of cracks by tree roots would positively correlate with tree height, due to stability and nutrient gathering arguments. Within the sampled population, there was an uneven distribution of seedlings (62.8%), saplings (21.9%) and adults (15.3%). All size classes were contagiously dispersed on the outer edges of the rock faces, despite our expectation about seedling dispersal. Lastly, the number of cracks used by the roots as well as the number of large cracks used showed some degree of positive correlation with tree height. These results suggest that (1) there are growth bottlenecks in the population, (2) the outer edges of rock faces are either popular for dispersal or essential for establishment, and (3) large cracks provide more stability and/or necessary nutrients for trees as they mature.