TITLE:
Synergistic Effect of Anthropogenic Disturbances on Offspring Demography of Pentadesma butyracea (Clusiaceae), a Threatened Tree Species in Benin (West-Africa)
AUTHORS:
M’Mouyohoun Kouagou, Olivier E. B. Ahouandjinou, Laurent Houessou, Aliou Dicko, Armand Kuyema Natta
KEYWORDS:
Fire, Habitat Size Reduction, Multiple Stressors, Pentadesma butyracea, Survival-Growth Trade-Off
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.10 No.8,
August
26,
2019
ABSTRACT: Understanding how ecological differences and
anthropogenic disturbances synergistically drive population dynamics decline is
critical for optimal management strategy definition. Main anthropogenic
disturbances such as habitat size reduction,
fire and non-timber forest harvest affect
demographic processes but our understanding of their interaction effects
in contrasted ecological conditions is
limited. We investigated the interaction effects of fruit harvest, fire, gallery forest size and distance to streambed
on density, recruitment, survival and
growth of Pentadesma butyracea offspring in dry and moist
ecological conditions. We randomly selected in each ecological region six P. butyracea populations. We then
established in each population, 10 subplots of 100 m2 within 1 ha to
assess offspring demographic performance from 2015 to 2017. Results showed that
fire suppressed the positive effect of large habitat size and amplified the
negative effect of increasing local aridity on offspring growth. Fire and
harvest synergistically reduced growth whereas offspring growth was resilient
to fire in moist ecological region. Moist
ecological conditions mitigated the negative effect of harvest on growth.
Harvest mitigated the surprise negative effect of large habitat size on
survival. However, in large gallery size, high harvest limited clonal
recruitment and growth. There was a positive interaction effect between harvest
and distance to streambed on survival (High harvest, Z = 2.045, p = 0.041,
Medium, Z = 2.060, p = 0.039) but a negative interaction effect on growth (High,
t = -2.357, p 0.05). Clonal offspring
grew faster than sexual offspring in high harvest populations. In moist region, offspring survived better in
large gallery forest size. In 2017, survival and growth were lower in large gallery forest. In 2017, offspring growth
was higher near the riverbed where the survival rate low. This study suggests
that management strategies should consider the interaction effects of
anthropogenic disturbances and climatic conditions.