Impact of Photosynthetically Active Radiation on Temperature, Relative Humidity, Wind Speed and Direction in Lubigi Cyperus papyrus L. Wetland Surface
Alfonse Opio *
Gulu University, Faculty of Science, Department of Biology, P.O. Box 166, Gulu, Uganda
Frank Kansiime
Makerere University, College of Agricultural and Environmental Sciences, Department of Environmental Management, P.O. Box 7062, Kampala, Uganda
Tom Otiti
Makerere University, College of Natural Sciences, Department of Physics, P.O. Box 7062, Kampala, Uganda
*Author to whom correspondence should be addressed.
Abstract
Photosynthetically active radiation (PAR) is dominant solar radiation reaching the earth surface. PAR changes in response to the position of the sun and length of the day can be complex and perhaps even counter – intuitive to ecosystems. Assessment of PAR on relative humidity (RH), temperature, wind speed and direction in Cyperus papyrus (papyrus) wetland canopy surface was done during the months of September, 2010 (wet month) and June, 2011 (dry month) when the sun is at the equator and Tropics of Cancer respectively.
PAR picked up in the morning (7.00 hour) and exhibited similar pattern during the months, although September values were significantly higher between 07.00 - 08.00 hours, 12.00 - 15.00 hours and at 19.00 hour. Significant difference in PAR at 19.00 hour was associated with significant temperature change between 20.00 to 21.00 hours. Significant temperature change between the months from 11.00 to 12.00 hours also occurred before that of PAR (12.00 - 15.00 hours). RH was significantly different between the months. Significant wind speed and direction between 07.00 - 08.00 hours was associated with significant PAR change between the months. Wind oscillation was easterly and southerly wind and significant difference in wind direction also occurred at 10.00 hour. Overall, data based on regression analysis indicate significantly strong correlation between PAR with RH, temperature and wind speed. Such changes in weather variables in relation to the sun’s position, and ecosystem services and development requires assessment.
Keywords: Papyrus, photosynthetically active radiation, relative humidity, temperature, wetlands, wind