Ecological strategies of tree species in the laurel forest of Tenerife (Canary Islands): an insight into cloud forest natural dynamics using long‑term monitoring data
Fecha
2018Resumen
In Tenerife (Canary Islands), the laurel forest is considered one of the most biodiverse ecosystems of the archipelago. This
study aims at providing useful information about tree species strategies and their natural dynamics in order to improve
understanding of the functioning of this ecosystem. The knowledge gained would be of great importance for laurel forest
conservation, not only in the Canaries, but also in Madeira and the Azores. Our main research question is: ‘Are the ecological
groups of laurel forest tree species, described in earlier studies based exclusively on regeneration strategies, consistent
with species functional traits, growth patterns and spatial distributions?’ We used data from six 50 × 50 m permanent plots
established in 1999 and re-measured in 2015, combined with information on twelve functional traits from newly produced
data or extracted from previous studies. For each species, we analyzed the abundance of seedlings/suckers, saplings and
adults inside the permanent plots. Two ordination methods were used to assess multivariate differences in functional traits
between species. Different mixed-effect models were tested to investigate effects of sites, individual tree size and competition
on tree growth rates. Finally we analyzed the spatial distribution of both saplings and adults and their interaction within
the six permanent plots. Our results were consistent with a classification of species into different ecological groups based
on (1) their shade tolerance: light-demanding versus shade-tolerant species and (2) their reproductive strategies: sexual
(i.e., seedlings), asexual (i.e., suckers) or both. These differences between light-demanding versus shade-tolerant and/or
seedling-producing species versus sucker-producing species were consistently observed across the species functional traits,
growth patterns and spatial distributions. Only one species, Viburnum rigidum Vent., presented singularities compared with
its previously established group. Because V. rigidum is mostly an understory species, we proposed to add a third aspect
to the classification scheme: understory versus canopy species. This led to a total of six ecological groups within fourteen
laurel forest tree species. Finally, this study also showed that the Tenerife laurel forest is still maturing and becoming richer
in species, which outlines the importance of its preservation.