Coffee and shade trees show complementary use of soil water in a traditional agroforestry ecosystem
Por:
Elena Munoz-Villers, Lyssette, Geris, Josie, Susana Alvarado-Barrientos, Maria, HOLWERDA, FRISO, Dawson, Todd
Publicada:
7 abr 2020
Resumen:
Globally, coffee has become one of the most sensitive commercial crops,
being affected by climate change. Arabica coffee (Coffea arabica) grows
in traditionally shaded agroforestry systems in tropical regions and
accounts for similar to 70 % of coffee production worldwide.
Nevertheless, the interaction between plant and soil water sources in
these coffee plantations remains poorly understood. To investigate the
functional response of dominant shade tree species and coffee (C.
arabica var. typica) plants to different soil water availability
conditions, we conducted a study during nearnormal and more pronounced
dry seasons (2014 and 2017, respectively) and a wet season (2017) in a
traditional coffee plantation in central Veracruz, Mexico. For the
different periods, we specifically investigated the variations in water
sources and root water uptake via MixSIAR mixing models that use delta
O-18 and delta H-2 stable isotope composition of rainfall, plant xylem
and soil water. To further increase our mechanistic understanding of
root activity, the distribution of below-ground biomass and soil
macronutrients was also examined and considered in the model as prior
information. Results showed that, over the course of the two
investigated dry seasons, all shade tree species (Lonchocarpus
guatemalensis, Inga vera and Trema micrantha) relied, on average, on
water sources from intermediate (> 15 to 30 cm depth: 58 +/- 18 % SD)
and deep soil layers (> 30 to 120 cm depth: 34 +/- 21 %), while coffee
plants used much shallower water sources (< 5 cm depth: 42 +/- 37 % and
5-15 cm depth: 52 +/- 35 %). In addition, in these same periods, coffee
water uptake was influenced by antecedent precipitation, whereas trees
showed little sensitiveness to antecedent wetness. Our findings also
showed that during the wet season coffee plants substantially increased
the use of near-surface water (+56 % from < 5 cm depth), while shade
trees extended the water acquisition to much shallower soil layers (+19
% from < 15 cm depth) in comparison to drier periods. Despite the
plasticity in root water uptake observed between canopy trees and coffee
plants, a complementary use of soil water prevailed during the dry and
wet seasons investigated. However, more variability in plant water
sources was observed among species in the rainy season when higher soil
moisture conditions were present and water stress was largely absent.
Filiaciones:
Univ Nacl Autonoma Mexico, Ctr Ciencias Atmosfera, Mexico City, DF, Mexico
Univ Aberdeen, Sch Geosci, Northern Rivers Inst, Aberdeen, Scotland
Inst Ecol AC, Red Ecol Func, Xalapa, Veracruz, Mexico
Univ Calif Berkeley, Dept Integrat Biol, Berkeley, CA 94720 USA
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