Plant communities linked with human environments in southern Peru

In the context of the landscape and history of the southern Peruvian Andean territory, a phytosociological approach to the vegetation linked to human activity is presented. To obtain a comprehensive study, we focused the study on different elements of the Andean landscape, including plant communities: crop terraces with Brassica rapa and Medicago hispida communities, irrigation channels with Mimulus glabratus and Polypogon interrupts communities roads with Altemantbera pungens and Lepidium bipinnatifidum communities, overgrazed areas with Bouteloua simplex, Michrochloa indica and Cyperus andinus, farmyards, dumps and wall bases of villages with ruderal communities with Malva parviflora and Urocarpidium peruvianum, and wall fissures with Parietaria debilis and Cheilanthes pruinata communities. The study area is especially the Colca canyon in the Arequipa Department (southern Peru), where traditional agriculture is practiced and where we lifted 144 plots following the BRAUN-BLANQUET methodology, adding 853 plots from other authors. In total, 997 plots and 426 species were considered. To interpret the variability and vertical continuum of the associations, we have used the concepts of basal community (BC), derived community (DC), and altitudinal form were used. Field and bibliographic tables were synthetized, and as a result of column comparisons, we have concluded with a diversity of 41 Andean associations and communities described for areas of human impact distributed in different climatic belts. From a syntaxonomical point of view, 10 new associations are described: Nassello pubiflorae-Stipetum mucronatae -supra- and orotropical communities associated with the crops of southern Peru where the soil has been turned using the Roman plough-, Chlorido virgatae-Pennisetetum villosi -thermo- and mesotropical communities on abandoned fields, wastelands and road margins in the Bolivian Andes-, Mimulo glabrati-Polypogonetum interrupti-streams and irrigation ditch vegetation with running waters-, Monnino ramosae-Boutelouetum simplicis - pioneer annual vegetation on sandy soils of the supratropical belt of southern Peru-, Hypseocharito bilobatae-Boutelouetum simplicis-pioneer annual vegetation on clayey soils of the supra- and low orotropical belts of southern Peru-, Pectocaryo lateriflorae-Boutelouetum simplicis-pioneer annual vegetation on clayey soils of the mesotropical belt of southern Peru-, Evolvulo arizonici-Muhlenbergietumperuvianae-pioneer annual vegetation on clayey soils of the supratropical belt of the eastern cordillera of Bolivia-, Urtico flabellatae-Urocarpidetum peruviani-nitrophilous meso- and supratropical vegetation on disturbed soils of dumps, street margins and wall bases of the houses of the villages of central and southern Peru-, Oxalido petrophilae-Cheilanthetum pruinatae-supratropical association in the fissures of the andesitic rocks and walls of the villages of southern Peru - and Cheilanthetum arequipensis-fissure vegetation of the andesitic rocks of the mesotropical belt of southern Peru. For all these associations, we have commented on their variability with sub-associations, derived communities, basal communities, altitudinal forms and geo-vicarious associations. To connect the vegetation linked to the crops on soils turned by the Roman plough in the supra- and orotropical belt, we have created the new alliance Hordeion mutici (while vegetation on soils turned by the Inca plough -"taclla"- belongs to the Calandrinion ciliatae) and the Calandrinietalia ciliatae order. The vegetation of irrigation ditches in the tropical Andes belongs to the new alliance Mimulion glabrati, and the hygronitrophilous ones to Rumicion cuneifolii and the Polygono hydropiperoidis-Rumicetalia cuneifolii. Pioneer annual vegetation of the Occidental Peruvian Andes belongs to the Monnino pterocarpae-Cyperion andinae, and for the meso- and supratropical rock vegetation we have described the Woodsio montevidensis-Cheilanthion pruinatae. Moreover, all vegetation types of the Colca canyon linked to human activity have been compared with other tropical Andean localities with similar ecological conditions, especially from central Peru, Bolivia and Ecuador, and also with extra-tropical conditions from Chile and Argentina.