Shrubs as foundation species in a high tropical alpine ecosystem: a multi-scale analysis of plant spatial interactions

Abstract

Background: Studies on plant-plant interactions in alpine ecosystems show a strong bias for temperate vs. tropical latitudes and pay limited attention to the implications of biophysical heterogeneity beyond the local plant scale. Aims: To evaluate the effects of a dominant shrub (Hypericum laricifolium) on community organisation, integrating multiple scales of analysis, in a high Andean páramo in Venezuela. Methods: We compared plant cover, species richness and Shannon diversity between plots placed under the shrub and outside (plant scale); quantified the spatial relations of Hypericum with its conspecifics, heterospecifics and rocks at different radial distances, using covariance functions (patch scale); analysed the effects of Hypericum shrubs on total species richness in the community (site scale); and evaluated the consistency of our results among four sites within the same region (between-site scale). Results: Average species richness, Shannon diversity, and the abundance of common forbs and conspecific shrubs were consistently higher inside the Hypericum shrub, while the exotic Rumex acetosella was more abundant in open areas. However, the aggregated spatial distribution of conspecifics and other species extended beyond the local plant scale and there were no clear effects of Hypericum shrubs on community-level species richness. Conclusions: Shrubs can function as foundation species in tropical alpine environments, modifying local community structure and alpha diversity, but not necessarily the species richness of the overall community. Our results stress the need of analysing multiple spatial scales to interpret the role of plant-plant interactions (facilitation/competition) in heterogeneous alpine ecosystems.

Facilitation and edge effects influence vegetation regeneration in old‐fields at the tropical Andean forest line

“…; Gómez‐Aparicio ; Cáceres et al. ), as well as research exploring the potential of some species to act as nurses in old‐fields where forests are reestablishing (Holl et al. ).…”

“…; Cáceres et al. ). However, in the more mesic conditions of tropical mountain forests this issue remains largely unexplored.…”

Lava Flows and Moraines as Corridors for Early Plant Colonization of Glacier Forefronts on Tropical Volcanoes

“…Similarly, Sklenar () reported that high elevation (>4600 m) plant species tend to grow associated with rock outcrops in the Ecuadorian super‐paramo, while Cáceres et al . () showed a positive correlation between large shrubs and rock cover in half of their study sites in the Venezuelan Andes.…”

Evidence of Facilitation Cascade Processes as Drivers of Successional Patterns of Ecosystem Engineers at the Upper Altitudinal Limit of the Dry Puna

“…In harsh systems, such as tropical alpine environments, these processes constitute basic elements of vegetation processes [4]. Previous studies highlighted that facilitative interactions are more common than competitive ones in conditions of high abiotic stress (i.e.…”

“…Moreover, they demonstrated how these nurse-induced microhabitat modifications positively influenced the physiological parameters of facilitated species [23]. However, other authors found contrasting results on the effect of ecosystem engineers on species richness at a wide scale [4]. One limitation in our current understanding of the impact of engineer species on the richness of plant communities is that most of the existing works analysed different ecosystem engineers separately, or were located in areas dominated by a single nurse species.…”