Ecosystem engineering by Fascicularia bicolor in the canopy of the South-American temperate rainforest

- Fascicularia bicolor accumulate litter and reduce temperature variation on trees.
- The mean cover of vascular plants was 44% higher in plots with F. bicolor.
- Fascicularia bicolor support a high number of invertebrate species.
- Results could be relevant to improve biodiversity conservation in degraded forests.

Ecosystem engineers are organisms that modify habitats and resource flows, they therefore could have a disproportionate impact on the diversity of ecological communities. Evidence suggests that trash basket epiphytes (TBE) can be considered ecosystem engineers of forest canopies, due to their relationship with arboreal soil availability and treetop communities. Here we evaluated whether the TBE Fascicularia bicolor (Bromeliaceae), modulates temperature and humidity in the forest canopy. We also investigated if this bromeliad is related with greater arboreal soil accumulation and is associated to higher diversity of other epiphytic plants and invertebrates in the canopy of the South-American temperate rainforest (SATR), in Chile. We measured temperature and humidity in ten trees within the forest before and after the experimental addition of F. bicolor. We also related the presence of F. bicolor with occurrence of soil macro-fauna and other canopy dwelling plants in a comparative field survey.Temperature variability in the canopy was reduced by F. bicolor. Soil availability was higher in sites with mats of F. bicolor. The richness of vascular epiphytes was unaltered by the presence of F. bicolor, but species composition differed between sites with and without mats on each tree. At the group level, the cover of lichens and bryophytes was greater in sites without F. bicolor, while vascular epiphytes show a larger cover in sites with F. bicolor. The species richness of invertebrates increased in treetop sites colonized by F. bicolor but species composition was not different from soil in branch bifurcations. Our results show that F. bicolor must be considered in forest management practices to determine which trees must be logged, in order to preserve the viability of populations of these key organisms in the treetops of South-American temperate rainforests.