The impact of reforestation on the climate of the Southeast
Date
2006
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Publisher
University of Delaware
Abstract
Human modification of the landscape can potentially have an impact on weather and climate. Numerous climate modeling studies indicate that deforestation or reforestation will have an impact on the climate. Yet, there is much less research that utilizes the climate record to confirm these findings. ☐ This study determined the impact of reforestation on the summer climate of the southeastern United States. Counties in the piedmont area of North Carolina, South Carolina, Georgia, and Alabama were grouped by amounts of forest cover during the period 1948-2001. Three levels of forest cover were compared using an air mass analysis: low, medium, and high forest cover. In addition, county groups with low levels and high levels of forest cover were tested for meaningful differences between temperature, precipitation, and soil moisture. ☐ The air mass analysis showed no consistent trends or differences in the climate attributed to forest cover. The additional analysis showed that when county groups with high levels of forest cover were compared to county groups with low levels of forest cover, there were no differences in the probability of precipitation or the distribution of precipitation events. Forest cover was also found to have no effect on precipitation when daily soil moisture estimates were stratified according to the degree and duration of moisture deficit periods (i.e. drought). Areas with high amounts of forest cover had larger diurnal temperature ranges (~0.3 oC) but lower daily variability of temperature range than areas with low amounts of forest cover. Removal of cloud cover to isolate periods of maximum energy exchange between the land surface and the atmosphere confirmed that areas with high amounts of forest cover had higher diurnal temperature ranges but showed decreasing differences between the two groups as soil moisture approached saturation. The temperature results are in agreement with climate models but the precipitation results contradict models predicting decreases in precipitation due to deforestation. These results verify those aspects of the land surface’s affect on climate that are well modeled but also point to model areas that are not well constrained and require further work. There is clearly the need for further development of land-atmosphere climate models and for further study of the climate record to understand how land surface alteration affects climate.