From beach to savanna: Vegetation transitions at Illinois Beach State Park.

摘要

As a starting point for this thesis, several key threads in the development of 20th Century Ecology and the phenomenological approaches of Goethe and Husserl were described. These considerations led to the search for morphological categories able to reflect large-scale ecological phenomena---such as found in the Intertropical Convergence Zone and Africa's rainforest/desert polarity---but also the effects of Plant Available Moisture (PAM) and Plant Available Light (PAL) on the vegetation found at a dune and ridge beach-plain located on the western shore of Lake Michigan at Illinois Beach State Park (IBSP). Using the releve method, data were gathered from twelve 100-square-meter plots aligned from shore to savanna over a 200m long section of IBSP. With leaf aspect-ratio and petiole presence serving as dependent variables, PAM and PAL as independent variables, high correlations were found between increased leaf aspect-ratio, increases in PAM, and lower levels of PAL Similarly, the presence of petioles correlated strongly with increases in PAM and decreases in PAL. These results suggest that selected morphological characteristics of plants at IBSP resonate with larger patterns found at the scale of the biosphere and of continents such as Africa.;Keywords. Plant Available Moisture (PAM), Plant Available Light (PAL), leaf aspect-ratio, petiole presence, expansion, contraction, vertical extension, lateral extension, peripheral expansion, beach, ridge, swale.