Résumé
Diversified coffee agroforests modify microclimate conditions in
comparison to monocultures, impacting the success of significant plant
pathogens, such as Hemileia vastatrix, which causes coffee leaf rust
(CLR). However, research is often limited to the dichotomous analysis of
shaded agroforestry systems or unshaded monocultures, often overlooking
the nuanced effect of shade tree trait diversity. Our study aims to
determine the cumulative effects of shade tree canopy architectural
characteristics and leaf functional traits in biodiverse agroforests on
microclimate modifications and CLR incidence. We measured plot-level
microclimate conditions (air temperature, relative humidity, leaf wetness
duration, throughfall kinetic energy) in three single-stratum and two
double-strata shade tree canopy treatments, including Erythrina
poeppigiana, Terminalia amazonia, and Chloroleucon eurycyclum. Commonly
reported canopy characteristics and leaf traits were compared to average
microclimate conditions and CLR incidence levels. We found that shade tree
trait expression significantly explained most microclimate conditions, and
that two key shade tree traits (canopy openness, leaf area) significantly
explain CLR incidence levels (R2 = 0.211, p =
0.036). Our results highlight the differences in microclimate
conditions and CLR incidence among biodiverse agroforests, as well as the
important explanatory power of shade tree traits. Specific effects of
shade tree traits on pathogen dynamics can cirectly inform agroforestry
system design (i.e. shade tree species selection) and sustainable coffee
farm management practices (i.e. pruning practices).