Neotropical forests are strongly determined by their environment. Tree species differ in their tolerance to and requirements of the environment, resulting in differentiating distribution patterns along environmental gradients. As a result, community composition and structure varies along these gradients. Species richness, for instance, is generally higher in high-rainfall areas and at low latitudes, while relationships with soil fertility are ambiguous. While local scale as well as continental scale patterns are well developed, studies on the mesoscale, of large importance for e.g national forest management and conservation planning, have received very little attention.
Bolivia features an extraordinary display of vegetation types at the mesoscale, probably related to its high geomorphological complexity and large climatic variation. This research proposes to (1) quantify species diversity, composition and forest structure along climate and soil gradients; (2) evaluate forest dynamic along these gradients in terms of abundance, recruitment, growth and mortality of the tree community; and (3) identify silvicultural forest types based on the studied community and environmental characteristics to recommend forest-specific management guidelines.
To address these objectives, data from a network of 250 one-ha permanent sample plots over an area about 280.000 km2 of Bolivian lowland forests will be used. All trees ³10 cm in diameter at breast height in each plot have been mapped, tagged, measured for their diameter, and identified as far as possible. In addition, liana infestation, crown illumination, and crown form have been evaluated; and the height has been estimated. Plots with intervals of 4-5 years of growth data will be used for dynamic analysis. Around 100 plots will be re-measured during two years of fieldwork. For each plot soil samples will be collected in the field and climatic data (precipitation, temperature) will be obtained from existing digital data sets and meteorological stations. Unknown plant species will be collected, identified and specimens will be send to different herbaria in Bolivia and the Netherlands.
This study will reveal the dynamics of Bolivian lowland forests, and will maximize the knowledge of their species diversity, composition and structure along the major environmental gradients. The research will address long-standing questions about factors controlling the diversity, abundance, and distribution of tree species in forest communities considering a broader region and a much larger dataset than previous studies. Species characteristics such as growth rate will be addressed across the environmental gradients. If species characteristics are forest specific, forest managers will have to stratify their forest management practices. Results obtained will provide technical guidelines for such a stratified forest management, tailored to local site conditions, ecosystem characteristics and species traits. |
