Ecology of Palms in northwestern Bolivia

Master Thesis

Palms constitute a conspicuous and beautiful component of nearly all tropical American forests. Palms are also both ecologically and economically very important. Some palm species are extremely abundant, and produce large quantities of fruits being the prime food resource for populations of mammals, birds and fishes, themselves providing proteins to hunting and fishing humans. Palms also produce numerous items directly exploited by human beings including poles for construction, fibers for handicraft, thatch, edible fruits, medicine, hunting gears, etc.

Palms are diverse and abundant in the western Amazon basin, particularly in the forests along the foot hills of the Andes mountains. They range from small species dominating the shrub layer in the shaded understory of rain forests and montane forests, to large species that are among the most common and widespread canopy trees, and a few palm species dominate extensive waterlogged areas. The particularly high diversity of palms in the western Amazon reflects, that this area is a dynamic, young landscape constantly reshaped by the erosion and depositions of rivers draining the Andean slopes and carrying sediments and nutrients with them. This result in a mosaic of forest formations mainly characterized by inundation patterns and soil characters; and each of them are characterized by different palms. Some palms thrive at flood plains inundated during the annual high water season, others grow at previous flood plains preserving relatively fertile soils, still others are found at much older nutrient poor soils, and in contrast to other trees palms thrive in permanently waterlogged areas, and therefore form huge stands in swampy areas.

Local people extract products from palms in different forest formations. But in Bolivia, little is known about the habitat preferences and the regeneration of palms, making it difficult to evaluate the potential impact of the human exploitation, and the conservation status of the individual species. The objectives of this study are to investigate the distribution and abundance patterns of palms at the community level, and to determine how environmental factors influence these patterns at the local scale. Palm communities will be delimited and described in the lowland rain forests of the Amazon region of northwestern Bolivia. Each palm community will be inventoried in order to record the diversity, density and regeneration of the local palms, and relate these patterns to environmental factors.

Field work will take place in the Amazon lowlands of the Madidi National Park in the department of La Paz. Madidi is among the world's most biologically diverse reserves, reflecting that many different landscapes are found here. In the lowland parts where the present project will be undertaken there are hills with old leached soils, old flood plains, current flood plains inundated anywhere from a month to one half year annually, poorly drained swampy areas, irregularly inundated areas, etc. The mean annual precipitation is 1927 mm and the mean temperature 25° C, corresponding to a typical lowland humid tropical climate. Field work is anticipated to be undertaken between ca. 200 m and 1400 m above sea level.

Linear transects will be installed within habitats and across the interface of adjacent habitats, e.g. from topographically lower to higher areas inundated during longer and shorter periods, respectively. Transects will be 50 x 500 meter divided into 100 subplots being 5 x 5 meters, and in each subplot all palm individuals including seedlings will be registered. Some palms have several trunks rising from the same base, and in these cases the individual trunks will be counted separately. Besides variables that may influence the palm community we will recorded in each subplot abiotic factors (inclination, , moisture, soil samples) and biotic factors (canopy openness, gap condition, forest type, organic mater, human disturbance).

To analyze the distribution patterns of palm communities and the factors controlling them we will use Non-metric Multidimensional scaling (NMS), Indicator Species Analysis, simple and partial Mantel Tests and multiple regressions on resemblance matrices. To compare the palm communities in the different transect, we will calculate similarity matrices using the Sørensen coefficient for presence-absence data, and the mathematically similar Steinhaus coefficient for abundance data.

We expect that this research will result in a description of the floristic and the diversity patterns of palm communities, viz. what species compose the individual palm community in the area, their relative abundance the different species, and the relationships with the environmental factors that define the communities. We hope this will provide useful background information for the management of palm communities, and for the conservation of economically important species.

Participant Adriana A. Sanjines Asturizaga^; supervisors Finn Borchsenius, Mónica Moraes & Henrik Balslev