Phenological patterns in a southern Amazonian tropical forest: implications for sustainable management

Phenological transects were employed to assess monthly leaf, flower, unripe fruit and ripe fruit abundance for a total of 1732 individual plants within five tropical forest habitats at the ‘Lago Caiman Research Camp’, Noel Kempff Mercado National Park, northeastern Santa Cruz Department, Bolivia. Fruit surveys along trails were conducted concomitantly to assess fruit availability for the resident terrestrial frugivore community. The results of the two methodologies are compared and discussed with respect to wildlife and forest management in the region. Phenological transects revealed that Cerrado forest, tall forest, low vine forest, Sartenejal (swamp) forest, and pied mont (premontane) forest, showed seasonal variations in flower, unripe fruit and ripe fruit abundance, however, the broad temporal patterns were significantly different across habitats. Seasonal variation in overall foliage abundance was only marked for Cerrado forest. Ripe fruit production within the study site was not significantly different across months, with different habitats peaking asynchronously in abundance. From a frugivory perspective, overall ripe fleshy fruit abundance also varied considerably between habitats, and again showed asynchronous peaks in habitat production. However, both methodologies revealed the early dry season (June–July) as a period of ripe fleshy fruit scarcity throughout the study area. This period represents a resource ‘bottleneck’ for the resident frugivore community and phenological results allowed the identification of a number of keystone fruit resources for the region. Furthermore, fruit resources which are super-abundant in the early–mid wet season (November–February) might also be considered keystone resources for the region, given that they are available in an otherwise fruit scarce forest. The dynamic spatial patterning of fruit availability at Lago Caiman suggests that certain habitats might be considered keystone habitats, since they provide the majority of fruit resources on a seasonal basis. Finally, the potential of phenological information in tropical forest management plans is discussed and underlined by the observation that rainfall in itself fails to predict fruit availability in the dominant habitats at Lago Caiman.