Microclimate inside a forest gap depends on gap diameter relative to tree height.

Evidence

The physical environment within a small open area surrounded by forest differs from that under the canopy or in a large open area. In a small opening, temperatures fluctuate more and light and soil moisture are both more abundant than under a closed canopy. As the opening size decreases, humidity increases, wind speed decreases, and temperatures remain more constant (Geiger, 1965). Opening size is frequently quantified as the DIE, ratio, where D is the diameter of the open area and H is the mean height of the surrounding stand (Geiger, 1965). Several studies (Jackson, 1959; Minckler, 1961; Berry, 1964; Minckler and Woerheide, 1965; Minckler etal, 1973) have shown light to increase with increased opening size, reaching a maximum when DIH ~ 2. — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 164

Light intensity and duration are greater in gaps. Soil and air temperature can be much higher in gaps and fluctuate over a greater range. Humidity in gaps is comparatively low, while evaporation from the soil surface is high. But at a few centimeters in depth, soil moisture may be higher in gaps than beneath mature-phase forest, where root uptake is greater (Lee, 1978). As a rule, the degree of microclimatological contrast produced by a treefall increases with gap size (Lee, 1978). — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 419

Categorization

• XREF: The D/H ratio is a concrete field-reading tool for interpreting what a gap in present structure implies about past light and moisture — central to the landscape-interpretation course. — connects to: In leafless spring forests light and moisture change little between gap and canopy — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 1442; Nutrient availability within a single-tree gap varies between crown and bole zones — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 1987; A tree’s typical mode of death determines the size of gap it creates. — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 388 (+3 more)
• corroborated: 2 independent passages support this claim — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 164; S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 419

Broader Connections

• In leafless spring forests light and moisture change little between gap and canopy #qualifies (0.75) — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 1442
• Nutrient availability within a single-tree gap varies between crown and bole zones #expands (0.72) — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 1987
• Gap size determines whether lateral branch growth or sapling height growth closes it #expands (0.72) — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 231
• A tree’s typical mode of death determines the size of gap it creates. #expands (0.70) — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 388
• Most forest gaps are small but large gaps contribute most total gap area. #expands (0.70) — S. T. A. Pickett and P. S. White, eds., The Ecology of Natural Disturbance and…, 387
• Forest age and composition changes cluster along disturbance-history boundaries #expands (0.70) — Tom Wessels, Forest Forensics, 30