Ole Reidar Vetaas


Professor , Biogeography


Department of Geography

Research groups


Research Abstract

My main research aim is to explain why species are distributed non-randomly in the environment. I am especially interested in the variation of biodiversity from the lowland with high human impact to the summits.  

In Biogeography and geographical ecology, the scale issue is very central; explanations for variation in biodiversity at landscape scale may not apply to crude macroecology scales. My applied research at landscape scale focuses on the effect of human utilization of vegetation and its consequences for biodiversity. The intermediate disturbance hypothesis and succession is central in this type of research endeavor. I am also interested to find out the effect of introduced species on the local biodiversity. The potential and the realised niche concepts are important in this research, both in theory and practice.

At the crude macro scale, I have always used large mountains and their gradients in bioclimate to elucidate the mechanism that influences the richness of species. For instance, the Himalayan range has tropical bioclimate in the lowland and glacier at the top that mimics the latitudinal gradient from equatorial tropical to the arctic zone. I apply these large-scale temperature elevation gradients as in situ experimental sites because they are superior natural non-manipulative or observational experiments in which dramatic changes in climatic characteristics occur over relatively short geographic distances. The experimental situation is even more ideal on discrete sample sites such as isolated oceanic islands with mountains, such as Tenerife and La Palma in the Canary Islands archipelago.

In these studies, I focus on the major unexplained pattern in biogeography that is the global biodiversity patterns. I use data collected and compiled by the natural history tradition to find the principal factors controlling the biodiversity of plants and animals.  I aim to prove that the Water-Energy dynamic model provides the most plausible causation of the major macro-scale patterns in biodiversity. The tenet of WED is simple: when potential evapotranspiration (PET) is low water will freeze and solid water is unavailable for most organisms, and when PET is high water will evaporate and be less available for most organisms. Liquid water as a limited resource is a crucial point because in the non-tropical areas water will potentially be unavailable due to freezing from a few days to almost the whole year. The Energy-productivity models and WED models emphasise how species are constrained by climate conditions and thus where species coexist, but at long temporal scales, the fundamental causes of species richness gradients are in essence the differences in speciation, extinction, and migration. Therefore I am also interested to find a pattern of endemics as well as the phylogenetic- age of families and genera that may elucidate past pattern that represents the legacy of the current diversity distributions

Academic article
Academic lecture
Academic literature review
Doctoral dissertation
Book review
Masters thesis
Popular scientific article
Academic chapter/article/Conference paper
Non-fiction book
Academic anthology/Conference proceedings

See a complete overview of publications in Cristin.

Vetaas, O.R., Shrestha, K.B.& Sharma, L.N. 2020. Changes in plant species richness after cessation of forest disturbance. Applied Vegetation Science, DOI: 10.1111/avsc.12545.

Vetaas, O.R., K.P. Paudel, & Christensen, M. 2019. Principal factors controlling biodiversity along an elevation gradient: water, energy and their interaction. Journal of Biogeography, 46: 1652-1663.  special issue -  von Humboldt anniversary.

Qian, H, Sandel, B., Deng, T & Vetaas, O.R. 2019, Geophysical, evolutionary and ecological processes interact to drive phylogenetic dispersion in angiosperm assemblages along the longest elevational gradient in the world, Botanical Journal of the Linnaean Society, 190, 333–344.

Vetaas, O.R., Grytnes, J.A., Bhatta, K & B.A. Hawkins 2018. An intercontinental comparison of niche conservatism along a temperature gradient. Journal of Biogeography, 45: 1104-1113.

Slik, JWF, Franklin, J…. Vetaas, O.R. et al. 2018.Phylogenetic classification of the world's tropical forests. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. 115:1837-1842.

Steinbauer, M. J., Field, R., …Vetaas, O.R. & Beierkuhnlein, C. 2016. Topography-driven isolation, speciation and a globally consistent pattern of endemism. Global Ecology and Biogeography, 25: 1097-1107

Vetaas, O.R., Vikane, J.H., Saure, H. I  & Vandvik, V. 2014. North Atlantic islands with native and alien trees: are there differences in diversity and species─area relationships? Journal of Vegetation Science, 25: 213–225.

Vetaas OR & Ferrer-Castan D 2008. Patterns of woody plant species richness in the Iberian Peninsula: environmental range and spatial scale. Journal of Biogeography, 35:1863-1878.

Grytnes, J.A. & Vetaas, O.R. 2002. Species richness and altitude: a comparison between simulation models and interpolated plant species richness along the Himalayan gradient, Nepal. American Naturalist, 159: 294-204.

Vetaas, O.R. & Grytnes, J.A. 2002. Distribution of vascular plant species richness and endemic richness along the Himalayan elevation gradient in Nepal. Global Ecology and Biogeography, 11: 291-301.



University of Bergen (NO) Jawhal Nehru University (IN) / Joint Indo-Norwegian research and education on water-related changes in Himalaya / Coordinator / DIKU (.3 mill NOK)

Biodiversity: a function of water and thermodynamics.  project  awaiting  NRC-funding