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Altitudinal distribution patterns of bryophytes in the Canary Islands and vulnerability to climate change
We report the pattern of bryophyte distribution through the elevation gradient of three Canary Islands (Fuerteventura, Tenerife and Gomera) assessing their vulnerability risk to climate change. We considered a conservative scenario of upslope climatic shift of 200–400 m and a drop in the upper limit of the cloud belt from 1500 to 1000 m. Climate change vulnerability was analyzed from the overlap between the predicted shift in isotherms or cloud-belt edges and the current species range, following the Colwell and colleagues's model. Liverworts show narrower ranges and tend to live at lower elevations than mosses. Perennials and long-lived shuttle species establish in the upper localities. Many perennials and most of the long-lived shuttle species grow in cloud forests. Many annual shuttle species and colonists establish in the lowest localities. Colonists also occupy the harsh summit in the highest islands. In accordance with the Colwell model, most elements of this bryoflora appears vulnerable to rapid climatic change. Upland extinction and contraction challenges the bryoflora on the driest, lowest island Fuerteventura; range-shift gaps do this on the highest island Tenerife. Liverworts tend to be more vulnerable to range-shift gaps; mosses are more vulnerable to upland extinction. On the lowest island, perennials and long-lived shuttle species are more vulnerable to upland extinction; perennials are also vulnerable to range-shift gaps. Colonists are most vulnerable to upland contraction or extinction on the high islands Gomera and Tenerife. Annual shuttle species tend to be more vulnerable to lowland attrition on these high, most humid islands. Many elements of the bryoflora of the upper limit of the cloud forests appear to be vulnerable, while most of the flora of other cloud forest areas presumably will not be so affected, with the exception of the most restricted species. A simple model illustrates the feasibility of preliminary assessments of climate change on organisms which show a lack of published detailed information on their distribution and biology. This assessment gains by incorporating estimates of biological attributes.