Gap dendrometer band measurements at the Coweeta Hydrologic Laboratory from 1992 to 2000 (Circumference measurements)

Tree mortality at small spatial scales represents background levels of forest disturbance in the southern Appalachians, and is the dominant and most frequent initiator of change in terrestrial ecosystems. Large-scale and rare episodic events (i.e., hurricanes, ice, etc.) may do more to influence tree replacement and stand composition in the long-run than do small scale tree mortality events. What is the ecological significance of small scale mortality events with respect to biotic and abiotic responses? We experimentally created typical (<300 m2) canopy gaps (girdling and herbicides) at two elevations in Rhododendron and non-Rhododendron areas. The measurements in this study included automated micro-environmental measurements (air and soil temperature), photosynthetically active radiation, %WC, hemispherical photography, dendrometer bands and repeated measurements, population dynamics and seedling physiology, in situ closed core N mineralization and nitrification, and small and large mammal seed and plant herbivory using exclosures. Here are some specific questions relating to this study. How are microclimate and nutrient (N) cycling affected by small scale canopy removal? What are the physiological and productivity responses of advanced regeneration? What is the productivity response of non-gap-maker trees (dominants, co-dominant, and saplings)? What strategy for recovery is most likely (seedling recruitment, sapling ingrowth, canopy closure)? How do all of the above relate to/regulate each other? What is the effect of elevation on response? How do responses differ in Rhododendron versus non-Rhododendron areas?