Plant–plant spatial interactions in the dry Puna (southern Peruvian Andes)

Abstract

Plant-plant interactions play a key role in regulating the composition of communities. The outcome of interactions is the net effect of both positive and negative interactions. Positive interactions (facilitation) are defined as non-trophic interactions that increase the average individual fitness of at least one of the species involved. The study area was the Salinas and Aguada Blanca National Reserve, in the southern Peruvian Andes, composed of Festuca orthophylla grassland (dry Puna). The research goals were to ascertain whether spatial interactions act in this plant community, in order to determine whether beneficiary species have speciesspecific spatial associations. Our findings indicate that the most important nurses were the tall tussock species. A direct correlation was observed between the dimension of the F. orthophylla tussocks and the number of beneficiary species. Twelve species were closely associated with nurse species; five occurred in relation with nurse plants but without any preference for one of them; four species grew both isolated and in relationship with nurse plants and six species mostly grew isolated on bare soil. Because of the impact of grazers, some plants cannot grow on open ground; in fact, the species most in need of spatial interactions are those without avoidance strategies and/or with broad leaves. F. orthophylla is the core of a clumped spatial pattern of vegetation. The importance of spatial interactions for biodiversity conservation seems to be closely related to environmental amelioration and to grazer activity because plants of low palatability often serve as biotic refuges for palatable plants.

Facilitation among plants in alpine environments in the face of climate change

“…Two of the most abundant life forms in alpine regions are cushion-forming plants and tussock grasses (Hedberg and Hedberg, 1979; Körner, 2003). Even though tussock grasses have been reported to be highly competitive for resources in dry environments (Gómez-Aparicio, 2009), a number of studies have shown that, within an alpine context, both life forms may act as efficient nurse plants (Callaway et al, 2002; Catorci et al, 2011; Cavieres et al, 2014). We take these two life forms as distinctive cases in the following two paragraphs to explore how the predicted variation in their buffering effects on the microenvironment in the face of climate change may drive their nurse-related impacts on other plants in alpine regions (Figure 6).…”

Shrub facilitation is an important driver of alpine plant community diversity and functional composition

“…The importance of facilitation by cushion plants in extreme alpine plant communities has been recognised globally (Callaway 1998;Kikvidze and Nakhutsrishvili 1998;Nuñez et al 1999;Cavieres et al 2002Cavieres et al , 2014Akhalkatsi et al 2006;Catorci et al 2011;Butterfield et al 2013), including reversing declines in species richness with increasing altitude (Cavieres et al 2014), acting as micro-refugia for unique phylogenetic lineages (Butterfield et al 2013), their role as keystone species (Reid et al 2010) and in maintaining regional and global alpine plant diversity (Cavieres et al 2014).…”

Plant clonal morphologies and spatial patterns as self-organized responses to resource-limited environments

“…For each type of plant, we focus on a reference species: Festuca orthophylla (Poaceae) for grasses and Pycnophyllum tetrastichum (Caryophyllaceae) for cushions. Each species can locally dominate the vegetation within the study area by forming largely monodominant patches contrasting with bare soils (figure 1; see also [37,38]). …”