Impact of tree shading on the microclimate of a coffee plantation: a case study from the Peruvian Amazon

Abstract

Agroforestry is considered to be one ofthe agricultural strategies that could help to adapt crops to climate change. As a case study, we compared the microclimatic conditions at a location where Coffea arabica was shaded mainly by Inga spp. with the conditions in an unshaded C. arabica monoculture in the same coffee plantation in the Pasco region in Peru. Air temperature, air humidity, soil temperature and soil water availability were measured over three years. The results indicate that tree shading reduced the mean air temperature by 0.4 ± 0.04 °C and soil temperature by 1.7 ± 0.3 °C, and increased air humidity by 3.9 ± 0.4% compared to the unshaded area. However, the monthly average air temperature and even the monthly maximum in the unshaded area did not greatly exceed the limits for photosynthesis (upper limit 34 °C). Moreover, the minimum monthly air temperatures were similar in the shaded and unshaded areas. The soil temperatures did, however, fluctuate more markedly in the unshaded area. One of the main findings of this case study was that soil conditions were drier in the shaded area, especially at the beginning and end of the dry season. This was probably due to increased total transpiration resulting from that contributed by the shade trees. Thus, higher water uptake in agroforestry systems might have a negative impact on the growth of coffee plants where water availability is a limiting factor.