Hourly gap microclimate measurements from the Coweeta Hydrologic Laboratory in 1993 and 1994

LTER Gap Project Overview
Fact:
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.
Hypothesis:
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.
Overall Question:
What is the ecological significance of small scale mortality events with respect to biotic and abiotic responses.
Approach:
Experimentally create typical (<300 m2) canopy gaps (girdling and herbicides) at two elevations in Rhododendron and non-Rhododendron areas.
Measurements:
-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
-small and large mammal seed and plant herbivory using exclosures
Specific Questions:
1) How are microclimate and nutrient (N) cycling affected by small scale canopy removal?
2) What are the physiological and productivity responses of advanced regeneration?
3) What is the productivity response of non-gap-maker trees (dominants, co-dominant, and saplings)?
4) What strategy for recovery is most likely (seedling recruitment, sapling ingrowth, canopy closure)?
5) How do all of the above relate to/regulate each other?
6) What is the effect of elevation on response?
7) How do responses differ in Rhododendron versus non-Rhododendron areas?