This variation seems to be correlated with a reduction in habitat area (Simpson, 1974) and globally, species richness in TAE is comparable to that for temperate alpine communities (Rundel et al., 1994). Understanding how TAE’s specific biogeographic features would affect plant community attributes, in particular species diversity

and endemism remains a promising area of research for both basic and applied ecologists. Only a handful of studies have focused explicitly on the patterns and/or mechanisms of plant–plant interactions in TAE. In total buy Ixazomib we found 16 papers which discussed – even succinctly – plant–plant interactions in TAE worldwide. While these interactions include both intraspecific and interspecific levels (Brooker et al., 2008) most available studies http://www.selleckchem.com/products/BIBW2992.html in temperate and sub-polar/alpine environments have analysed the latter level. Nevertheless, we also considered studies reporting intraspecific interactions when they brought interesting insights for the scope of our review. The resulting list was used to conduct a basic meta-analysis (see Table 1 for details on meta-data). In total, 56% of publications did focus of plant–plant interactions, the rest mentioning

it in only the discussion (e.g. Smith, 1981). From a geographical viewpoint, a large majority of studies were held in the two most widespread areas of TAE, the Andes (62%) and East Africa (19%). In contrast, no studies were reported in two other widespread TAE, Mexico and Indonesia-New Guinea.

Most studies were conducted in humid TAE whereas the only studies that focused on dry TAE examined the effects of one keystone tussock grass of the Central Andes, Festuca orthophylla ( Kleier and Lambrinos, 2005, Patty et al., 2010 and Catorci et Bumetanide al., 2011). From a methodological viewpoint, all designs were observational with the exception of one series of removal experiments in the Venezuelan páramo which examined intra- and interspecific interactions with seedlings of the giant rosette E. schultzii ( Smith, 1984). In terms of results, most studies revealed patterns of spatial associations between species (69%) whereas only 31% of the papers analysed the mechanisms sustaining the interactions. We discuss both observed patterns and proposed mechanisms below. Although not all positive spatial associations reflect positive interactions (e.g. Maestre et al., 2003 and Michalet et al., 2006), many works use it as a powerful exploratory estimate – including in alpine environments (e.g. Callaway et al., 2002, Cavieres et al., 2005, Barbier et al., 2006, Dullinger et al., 2007 and Cavieres and Badano, 2009). Reports of positive spatial associations in TAE are relatively common worldwide (see Table 1 for details).