air in the sheltered area was not still or stagnant. During daylight hours radiant energy caused strong buoyancy effects and a greater wind shear (gradient between any two levels), which resulted in greater turbulence. In total, a more strongly unstable atmosphere was found to exist in the lee of a shelterbelt during the daytime and a more intensely stable atmosphere existed at night. The literature on the effects of shelterbelts on CO2 levels is sparse.
Small temporary windbreaks consisting of corn rows or snow fences were spaced at various intervals in soybean fields to study the effects of windbreaks on CO2 levels and crop yields. Data from eleven tests showed that soybeans sheltered by temporary corn windbreaks grew taller, produced more dry weight, had a larger LAI, and produced higher grain yields (Radke and Burrows 1970) Table 9-4).