2004 Volume 77 Issue 5 Pages 321-335
Meteorological parameters were measured in mahogany (mogno)-black pepper (pimenta) agro-forestry sites at Parque Ecológico de Gunma in Santa Bárbara do Pará, Brazil in September 2001 in order to investigate the differences in microclimatic mitigation in relation to forest structure and growth. In site mogno africano (MAF) where African mogno and pimenta were planted four years ago, the tree height (H) was 14.9±0.9m and the canopy coverage (CC) was 59.40±9.22%. Likewise, in site mogno amazônico (MAM) where an agro-forestry of Amazonian mogno and pimenta has been tested for six years, H was 6.6±0.8m and CC was 35.48±5.36%. In site mato reservado (RES), which is a 30-year-old secondary forest with 24 woody species, H: 13.3±7.8m, CC: 72.39±8.23%, and in site rocado (ROC), which was clear-cut 10 months ago, eight perennial herbs and 21 pioneer woody species were found, but CC was the smallest (6.21±1.09%). With respect to the radiation balance, downward short wave radiation (SWdown) was ROC>MAM>MAF>RES, while upward short wave radiation was ROC>MAM>MAF_??_RES. Both net radiation and photosynthetically active radiation had a similar phase to SWdown. Temperature was also dependent on SWdown. But dew point temperature (Tdp) decreased faster in ROC and MAM than at the other sites because radiative cooling due to upward long wave radiation (LWup) was larger in the nighttime. When temperatures reached Tdp in ROC and MAM, the relative humidity became 100% and the absolute humidity kept decreasing as long as dew formation continued. From these circumstances, it is clear that the diurnal fluctuation of microclimatic environments near ground surfaces depends on CC, and it is believed that pimenta, which are fond of the shade, should be planted in RES with high microclimatic mitigation effects.
