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Climate change is leading to the global loss of open montane meadows by facilitating tree and shrub encroachment at high elevations. North America's coastal mountains are particularly vulnerable to these changes, as they are relatively low elevation compared with interior mountains and contain only small areas of alpine tundra. We compared aerial photographs from 1962 with those from 2005 covering three subalpine regions on Vancouver Island, British Columbia, to document the extent of changes in woody vegetation and investigate associations between vegetation change and topography. Mean proportional woody vegetation cover increased significantly from 0.75 ± 0.03 to 0.81 ± 0.03 between 1962 and 2005 (p < 0.0001). Relative increase in woody vegetation cover was greater at higher elevations and on northerly aspects. These findings confirm an upward expansion and infilling of trees and shrubs and a reduction of the area encompassed by open alpine tundra on Vancouver Island. Loss of open meadow conditions at high elevations in this region will likely have consequences for alpine plant and animal communities. Key words: climate change, ecosystem structure, subalpine, Vancouver Island, woody vegetation. Les changements climatiques entrainent le recul mondial des prairies de montagne en favorisant l'empietement des arbres et arbustes a haute altitude. Les montagnes cotieres de l'Amerique du Nord sont particulierement vulnerables a ces changements etant donne qu'elles sont relativement peu elevees comparativement aux montagnes situees a l'interieur du continent et qu'on y retrouve seulement de faibles superficies de toundra alpine. Nous avons compare des series de photographies datant de 1962 avec des photographies prises en 2005 qui couvrent trois regions subalpines sur l'ile de Vancouver, en Colombie-Britannique, afin de documenter l'ampleur des changements dans la vegetation ligneuse et d'etudier les associations entre les changements dans la vegetation et la topographie. La proportion moyenne du couvert de vegetation ligneuse a significativement augmente de 0,75 ± 0,03 a 0,81 ± 0,03 entre 1962 et 2005 (p < 0,0001). L'augmentation relative du couvert de vegetation ligneuse a ete plus prononcee aux altitudes plus elevees et sur les pentes exposees au nord. Ces resultats confirment l'expansion vers le haut et l'envahissement des arbres et des arbustes ainsi que la reduction de la superficie occupee par la prairie alpine sur l'ile de Vancouver. La perte des conditions associees aux prairies ouvertes a haute altitude dans cette region aura vraisemblablement des consequences pour les communautes alpines de vegetaux et d'animaux. [Traduit par la Redaction] Mots-cles: changements climatiques, structure des ecosystemes, subalpin, ile de Vancouver, vegetation ligneuse., Introduction Mountain ecosystems are among those most at risk from climate change (Lenoir et al. 2008; Dirnbock et al. 2011). Of great concern is the loss of open alpine tundra [...]

A detailed biological assessment of Africa's highest mountain explores how climate modulates the effects of human land use on plants, animals, microorganisms and a diverse array of ecosystem functions. How climate modulates the effect of human activity on Mount Kilimanjaro., Author(s): Robert M. Pringle Author Affiliations: How climate and human activity shape a mountain ecosystem Mountains support roughly one-third of all land-dwelling species and supply water for nearly half of [...]

Physiological research suggests that tropical insects are particularly sensitive to temperature, but information on their responses to climate change has been lacking--even though the majority of all terrestrial species are insects and their diversity is concentrated in the tropics. Here, we provide evidence that tropical insect species have already undertaken altitude increases, confirming the global reach of climate change impacts on biodiversity. In 2007, we repeated a historical altitudinal transect, originally carried out in 1965 on Mount Kinabalu in Borneo, sampling 6 moth assemblages between 1,885 and 3,675 m elevation. We estimate that the average altitudes of individuals of 102 montane moth species, in the family Geometridae, increased by a mean of 67 m over the 42 years. Our findings indicate that tropical species are likely to be as sensitive as temperate species to climate warming, and we urge ecologists to seek other historic tropical samples to carry out similar repeat surveys. These observed changes, in combination with the high diversity and thermal sensitivity of insects, suggest that large numbers of tropical insect species could be affected by climate warming. As the highest mountain in one of the most biodiverse regions of the world, Mount Kinabalu is a globally important refuge for terrestrial species that become restricted to high altitudes by climate warming. biodiversity | climate change | Lepidoptera | tropical ecology

Despite intensive research, we still have no general understanding of why plant invasions occur. Many different mechanisms of plant invasions have been proposed, but studies designed to investigate them often produce inconsistent results. It remains unclear whether this unsatisfying state of affairs reflects the complexity of the real world (in which every invasion is unique) or the failure to identify the key processes driving most plant invasions. Here we argue that greater generalization is possible, but only if we recognize that the ecological and evolutionary processes enabling a species to advance into a new area change during the course of an invasion. In our view, an invasion can often usefully be subdivided into a primary phase, in which the abundance of an often preadapted species increases rapidly (typically in resource-rich, disturbed habitats), and a secondary phase, in which further spread is contingent upon plastic responses or genetic adaptation to new ecological circumstances. We present various examples to show how this partitioning of the invasion phase sensu stricto produces new hypotheses about the processes underlying plant invasions. Some of these hypotheses can be conveniently tested by investigating plant invasions along strong environmental gradients such as those that occur in mountainous regions. Key words: conceptual model; environmental gradients; habitat invasibility; invasion phases; invasive plants; mountain area; species invasiveness.

The Mesozoic evolution of the Andean Cordillera of southern Patagonia is recorded in two formations that are now part of the fold-thrust belt: the Zapata Formation and the Punta Barrosa Formation. Extension in the Ultima Esperanza region began in the Late Jurassic with deposition of the marine volcaniclastic Tobifera Formation and eventually resulted in the full-fledged oceanic Rocas Verdes Basin. The Zapata Formation was deposited over a time span of ~50 m.y. in an irregular basin ultimately bordered by an Early Cretaceous arc to the west. It is characterized by interbedded shale and siltstone mostly deposited in shallow water and, in areas of oceanic crust emplacement, also as deep-water hemipelagic deposits. Sediments of the Zapata Formation were derived initially from local oceanic upwarps and Tobifera highs and later from the andesitic cover of the juvenile arc and/or exhumed oceanic crust. The paucity of sandstone in the Zapata Formation in the Ultima Esperanza region indicates a highly irregular basin partitioned by prominent horsts, with sand deposition confined to sub-basins closer to the arc. Changes in depositional regimes and sediment dispersal patterns related to the onset of Andean contraction and formation of the Magallanes foreland basin are recorded by sediments of the overlying Punta Barrosa Formation. This formation records the evolution of a fold-thrust belt on the basis of the multimodal mineralogical and geochemical character of its sandstone and shale. The presence of an arc is indicated, but nearby Andean metamorphic terranes are more significantly represented in Punta Barrosa sediments. Stratigraphic details across the Zapata and Punta Barrosa Formations indicate that deformation and development of a proto-Andean Cordillera in southern South America was initiated in the late Mesozoic and involved conspicuous crustal shortening. Keywords: Patagonian Andes, orogenic evolution, backarc basin, Magallanes foreland basin, provenance, geochemical modeling.

Predictable relationships among patterns, processes, and properties of plant communities are crucial for developing meaningful conceptual models in community ecology. We studied such relationships in 18 plant communities spread throughout nine Northern Hemisphere high-mountain subalpine and alpine meadow systems and found linear and curvilinear correlative links among temperature, precipitation, productivity, plant interactions, spatial pattern, and richness. We found that sites with comparatively mild climates have greater plant biomass, and at these sites strong competition corresponds with over-dispersed distribution of plants, reducing intraspecific patchiness and in turn increasing local richness. Sites with cold climates have little biomass, and at these sites a high proportion of species benefit from strong facilitative effects of neighbors, leading to an aggregated distribution of plants. Sites with intermediate, or relatively moderate climates are intermediate in biomass, and at these sites interactions are weak (or competition may be counterbalanced by facilitation), corresponding with a nearly random distribution of plants. At these sites species richness is lower than average. We propose that the relationship between interspecific spatial pattern and community richness reflects niche differentiation and/or construction, which allows for the coexistence of more species than would be possible with random, unstructured spatial distributions. Discovering the mechanisms that drive the relationships described here would further link functional and structural components of plant communities and enhance the predictive capability of community ecology. Key words: Alpine systems; climate change; competition; environmental stress; facilitation; plant interactions; precipitation; productivity; spatial pattern; species diversity; temperature.

Seedling establishment has long been believed to be rare on alpine tundra because of predicted life history trade-offs, the clonality of alpine species, and the harshness of the alpine climate. Contrary to the idea that seedlings are rare on alpine tundra, a 4-yr demographic study of seedlings at Niwot Ridge, Colorado, USA, found seedlings at high densities, particularly in wetter plant communities. Higher germination densities were associated with higher soil moistures both across communities and across time. Mortality of seedlings was highest in the first year and decreased in subsequent years. Species' abundances differed between seedling and adult populations. Many forbs that lacked vegetative reproduction were significantly more abundant among seedling populations, and many monocots and clonal forbs were more abundant among adult populations. In a comparison with published demographic rates, seedling recruitment and mortality rates of Niwot Ridge species fell above or within rates for a wide range of perennial species. Therefore, germination and seedling establishment stages are no more limiting to sexual reproduction in alpine plants than in other perennial plants. Key words: Colorado Rocky Mountains; demography; germination; plant community; recruitment; survival analysis; tundra.