School of Botany - Theses
Permanent URI for this collection
Search Results
1 - 1 of 1
-
ItemAbiotic edge effects in wet sclerophyll forest in the Central Highlands of Victoria, Australia( 1997)Edge effects are the physical and biotic gradients which occur in an ecotone intersecting two dissimilar ecosystems. This research aimed to characterize abiotic edge effects in wet sclerophyll forest adjacent to recently logged areas in the Central Highlands of Victoria, Australia. Changes in photosynthetically active photon flux density (PPFD), air temperature, and ambient vapor pressure (ea) were monitored in the first 100 m of two east-facing edge environments during late summer and early winter of 1997. Microclimatic variables were measured on a relatively fine scale in the edge environment by using a rope and pulley system which moved the sensors along the selected edge transects. Consistently declining gradients across the edge ecotone were observed for PPFD and air temperature. These radiation and temperature gradients were influenced by edge orientation, time of day, forest canopy structure, and cloud cover. A negative exponential regression was fitted to radiation data, and from this model, an index for measuring the distance of edge radiation penetration was developed. This distance, designated as d10, is the distance at which PPFD reaches 10% of interior forest values. Average d10 values on overcast and clear summer days were 68 m and 118 m, respectively. Temperature was typically still declining at the last point of measurement, which indicates that the width of the temperature edge zone is greater than 100 m. Current forest practice in Victoria provides rainforest buffer zones of 20 to 100 m of sclerophyll forest. This study shows that if rainforests are to be protected from edge-induced micro climatic change, these buffer widths may need to be increased.