Impacts of landscape configuration on plant recruitment in Amazonia

Collaborators: Emilio Bruna (University of Florida), John Kress (Smithsonian Institution), Marina Anciães (Instituto Nacional de Pesquisas Amazônicas – INPA) and Marina Côrtes (UNESP-Rio Claro, Brazil).

The diversity, composition, and dynamics of vegetation during succession are highly dependent on relationships with frugivorous animals. Birds are among the principal animal dispersal agents of tropical forest plant species. We are working on the Biological Dynamics of Forest Fragments Project (BDFFP) located 70 km north of Manaus, Brazil, to determine how forest fragmentation, secondary forest regeneration, and interspecific variation in avian foraging behavior influence the recruitment of Heliconia acuminata, a common understory plant in primary forests.

By using a combination of empirical and modeling approaches, we have elucidated the degree to which biotic and abiotic factors acting at various spatial and temporal scales contribute to recruitment of H. acuminata in this human-modified landscape. By mapping and measuring seedlings in long-term plots at high spatial resolution, radio-tracking bird dispersers, conducting feeding experiments to estimate seed gut passage rates, quantifying the abiotic environment (e.g., light availability), and developing detailed GIS vegetation maps of the area surrounding the fragments, we can integrate the necessary data in sophisticated spatially-explicit models of seed rain and seedling recruitment.

Marina Cortes, a former graduate student, developed microsatellite primers for H. acuminata and has genotyped over 2,500 individuals within this landscape at two time points, 1998 and 2005.  These snapshots in time represent fine-scale genetic structure before (1998) and after (2005) secondary forest re-growth in the matrix surrounding the forests. These data provide us with unique empirical and theoretical insights into the effects of landscape fragmentation and the characteristics of the surrounding landscape on disperser behaviour and population genetic structure, a vital contribution to ecology.

Figures 1 and 2. Prof. Uriarte and Prof. Bruna collecting data on the field and Heliconia acuminata.

Figure 3. Study site surrounding landscape.