As a young tropical volcanic island, La Réunion is subject to numerous biological invasions by exotic species arriving on the territory. In order to gain understanding in the spatial pattern of those species and their dependance on environmental conditions, we started a ``MIREN-like'' sampling of the native and exotic vegetation of road sides along two elevation transects.
The Mountain Invasion REsearch Network (MIREN) is dedicated at understanding patterns of invasion in mountain areas all around the World. Although La Réunion is not part of the network (yet!?), we chose to implement sampling of road-sides vegetation following the international standardized MIREN protocol. Sampling occurred every 200 m elevation step, wherever possible, under various weather conditions (see pics) ! The two transects start around 400 m a.s.l. up to 2200 m and are located on the leeward and winward sides of the island. Thanks to the local botanical expertise (and good coffee ...), all species including the tricky ones (grasses, sedges and orchids...) were recorded. Due to resource availability however, only the first plots along the roads were sampled at this stage.
Preliminary analyses of the data showed contrasted levels species richness patterns along the two transects, as well as distinct elevation patterns for native compared to exotic species.
This work is part of a collaboration with Severin Irl aimed at comparing elevation in native/exotic plant diversity along elevation transects in Canary Islands, Hawaï and La Réunion. Severin is currently working in Karl's Beierkuhnlein laboratory in Bayreuth (Germany).