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Web End = Oecologia (2016) 181:12331242
DOI 10.1007/s00442-016-3619-0
GLOBAL CHANGE ECOLOGY ORIGINAL RESEARCH
Received: 7 September 2015 / Accepted: 20 March 2016 / Published online: 12 April 2016 Springer-Verlag Berlin Heidelberg 2016
opposite of a priori expectations. Conversely, Clethra cuneata showed increased survival at higher mean temperatures, but survival also increased with higher absolute low temperatures and the presence of shade. Finally, the survival of Gynoxys nitida seedlings was insensitive to temperature but increased under shade. These ndings show that multiple factors can determine the upper distributional limit of species forming the current tropical treeline. As such, predictions of future local and regional tropical treeline shifts may need to consider several factors beyond changes in mean temperature. If the treeline remains stationary and cloud forests are unable to expand into higher elevations, there may be severe species loss in this biodiversity hotspot.
Keywords Timberline Freezing tolerance Ecotone
Climate change Species migration
Introduction
Many species are shifting their distributions to higher latitudes and altitudes in response to increasing global mean temperatures (Parmesan and Yohe 2003; Chen et al. 2011). In order to remain at equilibrium with climate and avoid severe range contractions, species must shift their ranges at a pace similar to that of climate change velocities (Thomas et al. 2004; Colwell et al. 2008). However, the majority of shifting species, and especially plants, are lagging behind concurrent changes in temperature (Chen et al. 2011; Freeman and Class Freeman 2014; Rehm 2014). The relative rates of species range shifts and temperature change are especially important in the tropics, given that there are often high levels of biodiversity and endemism in relatively small geographic areas (Myers et al. 2000).
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Web End = Seedling transplants reveal speciesspecic responsesof highelevation tropical treeline trees to climate change
Evan M. Rehm1,2,3 Kenneth J. Feeley1,2
Abstract The elevations at which tropical treelines occur are believed to represent the point where low mean temperatures limit the growth of upright woody trees. Consequently, tropical treelines are predicted to shift to higher elevations with global warming. However, tree-lines throughout the tropics have remained stationary despite increasing global mean temperatures. The goal of the study reported here was to build a more comprehensive understanding of the effects of mean temperature, low-temperature extremes, shading, and...