Doctoral Dissertation Research: Natural Regeneration and Management of Trees in Agroecosystems in a Seasonally Flooded Environment

Columbia University, New York NY

Investigators

Abstract

The conceptual interpretation of forest community establishment and maintenance in tropical forests is heavily influenced by the theoretical concepts of succession and gap dynamics. While these concepts are appropriate to upland forests we suggest that they are inappropriate to describe plant community dynamics for Amazon floodplain forests. On the floodplain seasonal inundation is the strongest mechanism influencing the ecological processes that maintain the landscape heterogeneity and complexity so characteristic of this environment. Floodwaters act most strongly on the edges of landscape elements-rivers, lakes, levees-where transitions in vegetation occur. This doctoral dissertation research project will provide an alternative conceptual interpretation of forest community dynamics on the Amazon floodplain which is based on the ecological functions of edges. Riverine farmers who take advantage of the rich alluvial floodplain soils also create edges in their small-scale agriculture production systems. Their production and resource management technologies also influence the development of forest communities. The focus of this research is on a single tree species native to varzea forests--Calycophyllum spruceanum, a tremendous tree in the coffee family--but broadly treats the composition and dynamics of floodplain forest environments. Research conducted at the landscape level combined with studies on the autecology of C. spruceanum will show how the distribution and population dynamics of this tree species are influenced by the fluvial dynamics acting on edges and by land use practices of varzea residents. Research will be conducted in several Peruvian and Brazilian Amazon floodplain forests and riverine villages. The project employs methodologies at both the landscape and field scales including participant-observation techniques, interviews with local farmers, land use surveys, vegetation inventories of agricultural fields and forests, and experimentation. The stand inventory data will be analyzed using Principal Components Analysis (PCA). A multivariable analysis will be employed to test the relationship of flood duration, light levels, and edge type to the establishment and growth of seedlings in fields, fallows, and forests. The outcome of this study will include an ecological and management analysis of the woody component of production systems developed by varzea residents and a monograph on the ecology of an important tree species native to the varzea. Amazon flooded forests provide critical habitat for fish and other animals and plants specially adapted to long periods of seasonally flooding. The maintenance of tree cover is critical for the conservation in this fragile environment which absorbs the floodwaters of the mighty Amazon River and its major tributaries over a period of four to six months annually. Despite its ecological and conservation importance, the Amazon flooded forest environment and the production systems of its inhabitants are not fully understood. To address the information gap this doctoral dissertation research project will focus on the natural and social processes that control the regeneration, establishment, and growth of tree species in the natural forests and landholdings of farmers. Non-indigenous riverine farmers, who occupy and steward these forests, are also often overlooked in development and conservation agendas. A second goal of this research project is to identify and promote their traditional knowledge and local technologies that maintain tree cover in this critical environment. The results of this project will be applicable to development and conservation programs specific to floodplain environments throughout Amazonia. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.