Brenda Lin. 2003. The Effect of Shade Tree Presence on Soil Moisture Availability in Coffee Agroecosystems

Measurement of ambient temperature and humidity, soil temperature and humidity, irradiation, precipitation, and evapotranspiration were taken in a low shade and a high shade coffee plantation in Chiapas, Mexico in the rainy season of 2002 and the dry season of 2003. Measurements of the two sites were compared in order to see which site was better able to buffer the agricultural system from water stress. Graphic comparisons, t-tests, and CV's were used to compare the performance of the two different shade regimes toward soil water availability. Results from the wet and dry season show the high shade site provided a cooler and wetter environment than the low shade site and allowed for less water loss from the system through evapotranspiration. Soil monitoring data show that the soils of the high shade site are generally cooler in the wet season and less variable to changes in the rain cycle. Dry season soil data shows the ability of the high shade site to hold water better when rains do occur. In such ways, the high shade site is better able to buffer the coffee agroecosystems from drought.