Revealing diversity patterns of vascular plants and their causes in semiarid high mountain regions. A top-down approach for Great Basin mountain ranges, USA

Grüninger, Friederike; Fickert, Thomas

doi:10.3112/erdkunde.2003.03.03

Cited by 2 publications

(1 citation statement)

References 13 publications

(21 reference statements)

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“…T he approach of a top-down scaling of plant diversity issues (Grüninger & Fickert 2003, Grüninger 2005 was applied to evaluate the decisive factors for the outstanding of species richness in the biodiversity hotspot of southern Ecuador. Unlike many other Andean areas, species richness in the Cordillera Real appears to be connected to nearly each of the mentioned ecological factors (Fig.…”

Section: Discussionmentioning

confidence: 99%

Reasons for an outstanding plant diversity in the tropical Andes of Southern Ecuador

Richter

Diertl

Emck

et al. 2009

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Long-term field studies in the scope of a multidisciplinary project in southern Ecuador revealed extraordinary high species numbers of many organismic groups. This article discusses reasons for the outstanding vascular plant diversity using a hierarchical scale-oriented top-down approach (Grüninger 2005), from the global scale to the local microscale. The global scale explains general (paleo-) ecological factors valid for most parts of the humid tropics, addressing various hypotheses and theories, such as the "greater effective evolutionary time", constant input of "accidentals", the "seasonal variability hypothesis", the "intermediate disturbance hypothesis", and the impact of soil fertility. The macroscale focuses on the Andes in northwestern South America. The tropical Andes are characterised by many taxa of restricted range which is particularly true for the Amotape-Huancabamba region, i.e. the so called Andean Depression, which is effective as discrete phytogeographic transition as well as barrier zone. Interdigitation of northern and southern flora elements, habitat fragmentation, geological and landscape history, and a high speciation rate due to rapid genetic radiation of some taxa contribute to a high degree of diversification. The mesoscale deals with the special environmental features of the eastern mountain range, the Cordillera Real and surrounding areas in southern Ecuador. Various climatic characteristics, the orographic heterogeneity, the geologic and edaphic conditions as well as human impact are the most prominent factors augmenting plant species diversity. On microscale, prevailing regimes of disturbance and environmental stresses, the orographic basement, as well as the general role on the various mountain chains are considered. Here, micro-habitats e.g. niches for epiphytes, effects of micro-relief patterns, and successions after small-sized disturbance events are screened. Direct effects of human impact are addressed and a perspective of possible effects of climate change on plant diversity is presented.

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Section: Discussionmentioning

confidence: 99%

Reasons for an outstanding plant diversity in the tropical Andes of Southern Ecuador

Richter

Diertl

Emck

et al. 2009

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To what extent do natural disturbances contribute to Andean plant diversity? A theoretical outline from the wettest and driest parts of the tropical Andes

Richter

2009

Adv. Geosci.

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This paper deals with natural disturbances and their impact on vascular plant enrichment at two climatically contrasting Andean ranges, i.e. the perhumid Cordillera Real in southern Ecuador and the arid Cordillera de Atacama in northern Chile. In the first case, main triggers for an additional input of pioneer species during succession stages initiated by perturbations are landslides, mudflows, and, to a lesser extent, cohort mortality, floods, and wildlife damages. Droughts and wind are stressors, which reduce plant growth but hardly plant diversity, in contrast to enhanced UV radiation with its mutagen effect. Though stress effects are similar in the Atacama, disturbance regimes differ considerably in this dry mountain environment. Here, most perturbations are of small dimension such as nitrogen inputs by feces of Lamoids and burrow activities of tuco-tuco mice, both of them fostering nitrophilous plant communities. Flooding, gelifluction, and other denudation processes such as sheet wash occur too, however, do not charge species enrichment in the dry Andes. Although the perhumid study site represents one of the world's plant diversity "hotspots" and, by contrast, the arid one a comparatively "coldspot", pioneer species during successive stages after natural disturbances contribute in a similar percentage to the total plant inventories (appr. 10% of the species numbers). Relatively seen, natural disturbances are most important for species enrichment in the Atacama (200–500 species per 10 000 km<sup>2</sup>), while most other ecological factors delimit plant survival. Instead, plant life at the Ecuadorian study area benefits from many climatic and edaphic site conditions, and consequently, disturbances are considered only one of many driving forces for its hotspot status (>5000 species per 10 000 km<sup>2</sup>)

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Revealing diversity patterns of vascular plants and their causes in semiarid high mountain regions. A top-down approach for Great Basin mountain ranges, USA

Cited by 2 publications

References 13 publications

Reasons for an outstanding plant diversity in the tropical Andes of Southern Ecuador

Reasons for an outstanding plant diversity in the tropical Andes of Southern Ecuador

To what extent do natural disturbances contribute to Andean plant diversity? A theoretical outline from the wettest and driest parts of the tropical Andes

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