The Lowland-to-Upland Transition--Modelling Plant Responses to Environmental Change

A published correlative model has predicted that the distributional limits of plants and vegetation zones on mountains will increase in altitude with global warming. I test this hypothesis using results from published experimental studies. Investigations and models of the responses of leaf growth to temperature are in accord with the prediction. However, the individualistic responses of species to CO₂ enrichment indicate that the prediction is unlikely to be true for all species: growth is stimulated by CO₂ enrichment for some species but not for others. Wind speed generally increases with altitude on mountains, and plants from high altitude tend to be more wind resistant than species from the lowland. Therefore it is expected that, particularly on wind-swept mountains, global warming will not necessarily be followed by the spread of lowland species into the uplands.