| Popis: |
A sparse coniferous forest occurs on exposed cliff faces of the Niagara Escarpment in Southern Ontario. This paper presents the first quantitative study of the organization of the vegetation in these areas. The large-scale features of the Niagara Escarpment cliff community have been quantitatively analyzed, and a formal description is given of the changes in the physical and biological environments across the gradient from the plateau at the top of the cliff to the talus at its base. There were marked changes in soil depth, available photosynthetically active radiation, species richness, local diversity, and life-form characteristics across the gradient. Similar discontinuites in abundance were found for the most abundant species. Scatterplots and correlation analyses showed strong relationships between abundance and the two environmental factors, soil depth and available photosynthetically active radiation; however, these relationships were found mainly for those species present on the plateau at the top of the cliff. These results suggest that while resource pool size might influence species distribution on the plateau, other factors such as competitive displacement and disturbance seem to regulate the abundance of species in the talus and on the cliff face. |
