Comunidades vegetales relacionadas con procesos criogénicos en Andes peruanos - Galán et al. 2014

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Article

Phytocoenologia Vol. 44 (2014), Issue 1-2, 121–161 Published online February 2014

Las comunidades vegetales relacionadas con los procesos criogénicos en los Andes peruanos Plant communities linked with cryogenic processes in the Peruvian Andes Antonio Galán de Mera, Boadilla del Monte, España, Eduardo Méndez, Mendoza, Argentina, Eliana Linares Perea, Arequipa, Perú, José Campos de la Cruz, Lima, Perú & José Alfredo Vicente Orellana, Boadilla del Monte, España Con 13 figuras y 6 tablas Abstract: The Andean Cordillera is the second highest mountain range in the world after the Himalayas and therefore, one of the places where the cryogenic manifestations are more prominent. Tropical Andean glaciers usually present an ice-cap form, and various geomorphological forms – rock glaciers, block streams, morainic deposits, cryoplanation surfaces (sometimes mixed with volcanic pumices) with polygon soils, and solifluction terraces – can be distinguished in the surroundings. The study was carried out in the main glacial zones of Peru: Cordillera Blanca, Cordillera Central, Department of Puno (Allincapac and Yuracjasa), Department of Arequipa (Coropuna, Huarancante, Ampato and Imata plains), and Department of Tacna near the Tutupaca volcano. Above 4000 m (oro- and cryorotropical bioclimatic belts) we documented 152 plots using the Braun-Blanquet method, adding 287 relevés from other authors from Peru, and also from Venezuela to southern Argentina and Chile. To interpret the variability, geographical distribution and vertical continuum of the associations, the concepts of basal community (BC), derived community (DC), altitudinal form and geographic race were used. Field and bibliographic tables were synthesized, and arranged using two dendrograms as a result of applying the Sørensen index to compare glacial vegetation between Peru and other regions of South America. Rock glaciers support a rupicolous vegetation dominated by Valeriana nivalis, and Saxifraga magellanica on the more humid rocks. Block streams contain specific plant communities with Xenophyllum species (X. ciliolatum, X. dactylophyllum, X. decorum, X. digitatum and X. poposum), but Chaetanthera is also very important in these biotopes across the Andes. Cryoplanation surfaces, with more stable and deep soils, present a greater diversity of plants, such as Anthochloa lepidula, Dielsiochloa floribunda, Lachemilla frigida, Mniodes coarctata, Nototriche obcuneata, N. pedicularifolia or N. turritella. On solifluction terraces and flood surfaces, communities with Festuca rigescens and Trichophorum rigidum can be distinguished respectively. Deep clayey soils, support small pasturages of Deyeuxia minima and Aciachne pulvinata sometimes grazed, while the cushion vegetation caused by snowbreak streams is represented by Deyeuxia ovata and Werneria aretioides. From a syntaxonomical point of view, 32 Peruvian plant communities were recognized. Rock communities are the Senecio bolivarianus community – mono-specific plant community on humid rocks distributed form Huancayo to Cusco, the Asplenio triphylli-Melpomenetum moniliformis ass. nova – a rupiculous association installed on granitic rocks of the Cordillera Blanca, the Senecio algens community – associated with the basal part of the rocks of the humid puna, and the Senecioni culcitioidis-Valerianetum nivalis – a characteristic rock community usually present on andesites and basalts from Lima to Cordillera El Barroso (Tacna) [this association includes the subassociation saxifragetosum magellanicae, found on semi-permanent humid rocks, the geographic race with Draba cryptantha (Cordillera Central), the geographic race with Draba brackenridgei (near Cotahuasi Canyon, Arequipa), the geographic race with Draba cuzcoensis (near Colca Canyon, Arequipa), and the thermic altitudinal form with Woodsia montevidensis (Callalli, Arequipa)]. The Xenophyllo-Englerocharion peruvianae alliance is represented by the following communities: Xenophyllo ciliolati-Plettkeetum cryptanthae – a humid puna association present on block streams and morainic deposits with superficial stones from the Cordillera Blanca to Allincapac (Puno) [this association includes an altitudinal form with Anticona glareophila, from the limits of the vegetation of the Cordillera Central, a variant of semi-fixed blocks with Xenophyllum digitatum, a variant of mobile blocks with Xenophyllum ciliolatum, a derived community (DC) with Chaetanthera cochlearifolia from Central Peru, found on clayey places that will evolve to the polygon soils colonized by the Stangeo rhizanthae-Weberbaueretum rosulantis association, and a DC with Valeriana globularis and Anthochloa lepidula on the same environments from southern Peru], and the Poa gymnanthaCerastium peruvianum community, documented on volcanic conglomerates from Callalli (Arequipa). Nototricho obcuneatae-Xenophylletum poposi – installed on semi-fixed blocks of the altiplano of Peru and Bolivia in drysubhumid climate (its variability presents the sub-associations valerianetosum nivalis as a rupiculous aspect, and mniodetosum coarctatae on lightly sloping polygon soils), Nototricho-Mniodetum coarctatae ass. nova – cryorotropical vegetation on flat polygon soils enriched with the volcanic pumices of the altiplano, and the Belloo piptolepis-Dissanthelietum calycini – that indicates wetter soils without volcanic pumices in the altiplano – belong to the Nototrichion obcuneatae alliance. The Deyeuxion minimae alliance indicates deeper and more humid soils, where we can differentiate five associations: Nototricho pinnatae-Lachemilletum frigidae – present on the rock cornices and polygon soils coming from intrusive geologic materials of the Cordillera Blanca, Pycnophyllo mollis-Festucetum rigescentis – very typical on solifluction terraces of the humid puna of Peru

© 2014 Gebrüder Borntraeger, 70176 Stuttgart, Germany DOI: 10.1127/0340-269X/2014/0044-0576

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