Doctoral Dissertation Research: Patterns of Species Composition and Stand Age: The Importance of Dispersal, Species Interactions, and Habitat Preference

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

The plant species composition of deciduous forest communities varies considerably from place to place. It is not fully understood what determines whether or not a given plant will be located in a given area. Plants are sometimes limited to specific areas because of their inability to tolerate certain environmental conditions, which may be the result of differences in the soil where they grow or the result of changes brought about by other plants or trees already growing at a site. Elsewhere, plants may be limited by their ability to get seeds or other reproductive material to a new site. This doctoral dissertation research project will examine the role that plant dispersal and forest age have in determining spatial pattern in the herbaceous vegetation located underneath the canopy trees in the hardwood-hemlock forest of the Edmund Niles Huyck Preserve in central New York State. The Huyck Preserve provides the opportunity to study forest change over the last 150 years, because most of the area of the preserve was logged sometime during that time period, thereby providing a mosaic of forest types of varying age. The goals of this project are to determine if the type of dispersal a plant uses is related to whether or not it is present in a forest stand of a certain age and to determine if the likelihood of a species being contained in an area is dependent on that species being present in a nearby area. These relationships will be determined by examining the vegetation and the age of 30 to 40 forest stands of the Huyck Preserve. The locations of these stands will be specificed along with their distances from each other. The plant species located in these areas will be grouped by the type of dispersal they use to propogate themselves (wind, animal, gravity, etc.) as well as patterns associated with the age of forest stands. Among the hypotheses that will be explored is whether species using rapid, long-distance dispersal will appear in younger areas before species using slower, more geographically restricted modes of dispersal. Species composition in each area will be compared with species composition in adjacent areas. A hypothesis to be tested in this facet of the project is whether the species composition of an area is dependent on the species composition of other areas. This dependency may also be influenced by physical factors like wind or slope direction, as there may be greater concentration of species in areas located immediately downwind or downslope from established species. These results should help to clarify role that dispersal plays in determination of species composition patterns. This research will help advance understanding of the role plant dispersal plays in determining which species live where. This will complement what already is known about other factors that influence where plants live, such as how plants interact with the environment and how they interact with other plant species. This type of knowledge is necessary in a conservation context, because knowing the processes that maintain species diversity will help design plans for preservation of species, communities, and ecosystems. Land managers must know which processes increase or decrease species diversity on their lands before they can make informed decisions about the types of actions that should be taken to best preserve them or restore habitat. Understanding which processes are necessary to preserve maximum diversity can lead to more informed decisions about assigning protection priorities to various areas in scenarios involving limited monetary resources. 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.