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A floristic-ecological classification of the shrublands of the dry Bolivian Altiplano

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Navarro, Gonzalo and Molina, José antonio (2019) A floristic-ecological classification of the shrublands of the dry Bolivian Altiplano. Phytocoenologia, 49 (2). 199 -208. ISSN 2363-7153

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Official URL: https://www.schweizerbart.de/papers/phyto/detail/49/90498/A_floristic_ecological_classification_of_the_shrublands_of_the_dry_Bolivian_Altiplano



Abstract

Aims: To identify shrubland types of the Bolivian Altiplano based on their floristic composition and on ecological factors. Location: Central and southern Bolivian Altiplano (Bolivia, central-western South America). Methods: Vascular plants were recorded in a field survey of 101 relevés (10 m2). Relevés were subjected to hierarchical agglomerative classification to define numerical vegetation groups. Classification techniques were based on the β-flexible linkage method (β = -0.25) with Sørensen distance. The highest crispness values defined the level of the main number of clusters identified. Diagnostic species were identified by means of the phi coefficient of fidelity. Canonical Correspondence Analysis, the Kruskal-Wallis test and a Z test were performed to assess the key ecological drivers of diversity in the Altiplano shrubland vegetation. Results: Based on numerical analyses of phytosociological relevés, our work proposes four vegetation types of shrublands in the dry central and southern Bolivian Altiplano. They correspond to the following: tolillares – thickets of Fabiana densa – of the central-southern Altiplano with Junellia seriphioides; tolillares of the central-northern Altiplano with Lobivia pentlandii; lampayares – thickets of Lampayo castellani – with Parastrephia quadrangularis; and tolares – thickets of Parastrephia sp. pl. – with Parastrephia lepidophylla and Junellia minima. The bioclimatic variables were the ones best explaining the distribution patterns of the shrubland vegetation in the dry Bolivian Altiplano. Specifically, they separate the tolillares of the central-northern Altiplano with Lobivia pentlandii – at localities with a higher annual precipitation, annual ombrothermic index, and ombrothermic index of the wettest quarter – from the tolillares of the central-southern Altiplano with Junellia seriphioides. These bioclimatic gradients also position lampayares at localities with a lower than average value of annual precipitation, annual ombrothermic index, and ombrothermic index of the wettest quarter. Significant differences were found when comparing the topographic position, the degree of soil drainage and the frequency of flooding between the vegetation of tolillares on the one hand, and the vegetation of lampayares and tolares, on the other. Lampayares were exclusively related to sandy soils. Conclusions: Our four groups characterize variation within the habitat and elucidate bioclimatic gradients and soil features with related habitats. This knowledge could provide basic information on the vulnerability of different Altiplano shrubland habitats to climatic fluctuations, as this area is highly vulnerable to extreme periods of drought associated with the regional effects of climate change as well as to anthropogenic factors. Taxonomic reference: Bolivia Catalogue (2014; http://www.tropicos.org/Project/BC). Syntaxonomic reference: Navarro (1993, 2002, 2011). Abbreviations: CCA = Canonical correspondence analysis; Io = annual ombrothermic index; Iod = ombrothermic index of the driest quarter; Iow = ombrothermic index of the wettest quarter; Tw = mean temperature of the wettest quarter.

Resumen (otros idiomas)

Este trabajo tuvo como objetivo principal identificar los tipos de matorrales del altiplano seco boliviano en función de su composición florística y ecología. Para ello, se muestrearon 101 parcelas de 10 m2 . Se estimó el porcentaje de cobertura para cada especie y se recogieron las características edáficas. Las variables climáticas de cada localidad se obtuvieron de Worldclim. Los inventarios florísticos se sometieron a una clasificación aglomerativa jerárquica para definir grupos de vegetación numérica. Las técnicas de clasificación se basaron en el método de enlace β-flexible (β = -0.25) con la distancia de Sørensen. El mayor valor de ‘cripness’ definió el número agrupaciones consideradas. Las especies diagnósticas fueron identificadas por medio del coeficiente de fidelidad ‘phi’. Se identificaron los cuatro tipos de matorrales siguientes: a) tolillares -matorrales de Fabiana densa y Junellia seriphioides- del centro-sur del Altiplano; b) tolillares con Lobivia pentlandii del centro-norte del Altiplano; c) lampayares -matorrales de Lampayo castellani- con Parastrephia quadrangularis; y d) tolares -matorrales de Parastrephia sp. pl.- con Parastrephia lepidophylla y Junellia minima. El análisis canónico de correspondencias mostró las relaciones entre las variables florísticas y las climáticas. Este análisis de gradiente directo separó los tolillares del centro-norte del Altiplano, relacionados con localidades de mayor precipitación anual, e índices ombrotérmicos más altos, de los tolillares del centro-sur propios de localidades con valores menores a la media para esas variables. Estos gradientes bioclimáticos también situaron a los lampayares en localidades con valores inferiores al promedio de precipitación anual e índices ombrotérmicos. La prueba de Kruskal-Wallis y el Z-test mostraron diferencias significativas al comparar la posición topográfica de la comunidad, el grado de drenaje del suelo y la frecuencia de inundación entre la vegetación de tolillares, por un lado, y la vegetación de lampayares y tolares, por otro. Los lampayares se relacionaron exclusivamente con suelos arenosos. Los resultados de este trabajo proporcionan información básica sobre la vulnerabilidad de los diferentes matorrales del Altiplano al cambio global. El Altiplano es un área expuesta a períodos extremos de sequía asociados a los efectos regionales del cambio climático así como a otros factores antropogénicos.

Item Type:Article
Uncontrolled Keywords:Andean region, diagnostic species, Fabiana densa, Lampayo castellani, Lobivio ferocis-Fabianion densae, numerical classification, orotropical climate, Parastrephia lepidophylla, Parastrephion lepidophyllae, plant-community type, shrubland
Subjects:Medical sciences > Biology > Botany
Medical sciences > Biology > Ecology
ID Code:57195
Deposited On:02 Oct 2019 18:06
Last Modified:02 Oct 2019 18:06

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