The effect of conspecific density, herbivory, and bamboo on seedling dynamics of a dominant oak in a Neotropical highland forest
Conspecific negative density dependence (CNDD) is one of the main mechanisms influencing diversity maintenance in tropical forests. Tropical highland forests, in contrast to most lowland forests, are commonly dominated by a few tree species, and testing the importance of density dependence effect...
|Calderón Sanou, Irene, Ríos Reyes, Luis Diego, Cascante Marín, Alfredo, Barrantes Montero, Gilbert, Fuchs Castillo, Eric J.
Conspecific negative density dependence (CNDD) is one of the main mechanisms
influencing diversity maintenance in tropical forests. Tropical highland forests, in
contrast to most lowland forests, are commonly dominated by a few tree species,
and testing the importance of density dependence effects on seedling establishment
of dominant trees may provide insights on the mechanisms regulating population dynamics
and forest composition of tropical highlands. We tested the effect of CNDD
regulation on seedling survival and recruitment of Quercus costaricensis, a monodominant
oak in the Talamanca highland forests of Costa Rica. We used Ripley's K and
generalized linear mixed models to test the effects of conspecific density, distance
to the nearest adult, density of Chusquea bamboo shoots, and herbivory on the annual
survival probability of 3579 seedlings between 2014 and 2017. We did not find
a significant effect of CNDD on seedling survival. However, bamboo density and
herbivory both significantly decreased oak seedling survival. All seedlings had signs
of herbivory and predator satiation may explain the lack of density dependent regulation
in seedlings of this species. We argue that the lack of intraspecific density regulation
at the seedling stage may contribute to explain the dominance of Q. costaricensis
in the highland forests of Costa Rica. Local seedling dynamics of this endemic oak are
instead regulated by herbivory and the density of Chusquea.