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Diverging responses of tropical Andean biomes under future climate conditions.

Tovar C, Arnillas CA, Cuesta F, Buytaert W - PLoS ONE (2013)

Bottom Line: Our results show a heterogeneous response to climate change.These results challenge the common believe that climate change will lead to an upslope displacement of biome boundaries in mountain regions.Lastly, a significant part of the area expected to change is already affected by land use changes, which has important implications for management.

View Article: PubMed Central - PubMed

Affiliation: Centro de Datos para la Conservación, Universidad Nacional Agraria La Molina, Lima, Perú. ctovar@lamolina.edu.pe

ABSTRACT
Observations and projections for mountain regions show a strong tendency towards upslope displacement of their biomes under future climate conditions. Because of their climatic and topographic heterogeneity, a more complex response is expected for biodiversity hotspots such as tropical mountain regions. This study analyzes potential changes in the distribution of biomes in the Tropical Andes and identifies target areas for conservation. Biome distribution models were developed using logistic regressions. These models were then coupled to an ensemble of 8 global climate models to project future distribution of the Andean biomes and their uncertainties. We analysed projected changes in extent and elevational range and identified regions most prone to change. Our results show a heterogeneous response to climate change. Although the wetter biomes exhibit an upslope displacement of both the upper and the lower boundaries as expected, most dry biomes tend to show downslope expansion. Despite important losses being projected for several biomes, projections suggest that between 74.8% and 83.1% of the current total Tropical Andes will remain stable, depending on the emission scenario and time horizon. Between 3.3% and 7.6% of the study area is projected to change, mostly towards an increase in vertical structure. For the remaining area (13.1%-17.4%), there is no agreement between model projections. These results challenge the common believe that climate change will lead to an upslope displacement of biome boundaries in mountain regions. Instead, our models project diverging responses, including downslope expansion and large areas projected to remain stable. Lastly, a significant part of the area expected to change is already affected by land use changes, which has important implications for management. This, and the inclusion of a comprehensive uncertainty analysis, will help to inform conservation strategies in the Tropical Andes, and to guide similar assessments for other tropical mountains.

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Elevational range changes for A1B 2040–2069.Glaciers and cryoturbated areas, paramo, humid puna and evergreen montane forest show upward displacement of the lower boundary. This can be observed in the left hand side of the accumulation curves, where curves of all models for the future (in grey) are higher than the curves for the present (dotted line). Seasonally dry tropical montane forest, montane shrubland and xeric pre-puna show downslope expansion in the lower boundary where future curves are lower than the present one. Upper boundary show upward displacement for almost all biomes, observed at the right hand side of the accumulation curves. The x-values were scaled from 0 to 1 to compare landscapes of different size.
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pone-0063634-g002: Elevational range changes for A1B 2040–2069.Glaciers and cryoturbated areas, paramo, humid puna and evergreen montane forest show upward displacement of the lower boundary. This can be observed in the left hand side of the accumulation curves, where curves of all models for the future (in grey) are higher than the curves for the present (dotted line). Seasonally dry tropical montane forest, montane shrubland and xeric pre-puna show downslope expansion in the lower boundary where future curves are lower than the present one. Upper boundary show upward displacement for almost all biomes, observed at the right hand side of the accumulation curves. The x-values were scaled from 0 to 1 to compare landscapes of different size.

Mentions: The upper boundaries of almost all biomes show an upslope displacement (Figure 2). The only exceptions are the biomes restricted to the upper parts of the Andes, i.e. glaciers and cryoturbated areas, and the paramo. The trends for the lower limit of the distribution of each biome, however, are more variable. The majority of biomes are also projected to experience an upslope displacement of their lower limit (Figure 2). This shift is more marked for glaciers and cryoturbated areas, paramo, humid puna and the evergreen montane forest and to a lesser degree for the xeric puna. Yet our model projects downslope expansion of the lower boundary of several biomes: seasonally dry tropical montane forest, xeric pre-puna and especially montane shrubland. The puna biomes, and especially the xeric puna, show the least change in their elevational range.


Diverging responses of tropical Andean biomes under future climate conditions.

Tovar C, Arnillas CA, Cuesta F, Buytaert W - PLoS ONE (2013)

Elevational range changes for A1B 2040–2069.Glaciers and cryoturbated areas, paramo, humid puna and evergreen montane forest show upward displacement of the lower boundary. This can be observed in the left hand side of the accumulation curves, where curves of all models for the future (in grey) are higher than the curves for the present (dotted line). Seasonally dry tropical montane forest, montane shrubland and xeric pre-puna show downslope expansion in the lower boundary where future curves are lower than the present one. Upper boundary show upward displacement for almost all biomes, observed at the right hand side of the accumulation curves. The x-values were scaled from 0 to 1 to compare landscapes of different size.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646809&req=5

pone-0063634-g002: Elevational range changes for A1B 2040–2069.Glaciers and cryoturbated areas, paramo, humid puna and evergreen montane forest show upward displacement of the lower boundary. This can be observed in the left hand side of the accumulation curves, where curves of all models for the future (in grey) are higher than the curves for the present (dotted line). Seasonally dry tropical montane forest, montane shrubland and xeric pre-puna show downslope expansion in the lower boundary where future curves are lower than the present one. Upper boundary show upward displacement for almost all biomes, observed at the right hand side of the accumulation curves. The x-values were scaled from 0 to 1 to compare landscapes of different size.
Mentions: The upper boundaries of almost all biomes show an upslope displacement (Figure 2). The only exceptions are the biomes restricted to the upper parts of the Andes, i.e. glaciers and cryoturbated areas, and the paramo. The trends for the lower limit of the distribution of each biome, however, are more variable. The majority of biomes are also projected to experience an upslope displacement of their lower limit (Figure 2). This shift is more marked for glaciers and cryoturbated areas, paramo, humid puna and the evergreen montane forest and to a lesser degree for the xeric puna. Yet our model projects downslope expansion of the lower boundary of several biomes: seasonally dry tropical montane forest, xeric pre-puna and especially montane shrubland. The puna biomes, and especially the xeric puna, show the least change in their elevational range.

Bottom Line: Our results show a heterogeneous response to climate change.These results challenge the common believe that climate change will lead to an upslope displacement of biome boundaries in mountain regions.Lastly, a significant part of the area expected to change is already affected by land use changes, which has important implications for management.

View Article: PubMed Central - PubMed

Affiliation: Centro de Datos para la Conservación, Universidad Nacional Agraria La Molina, Lima, Perú. ctovar@lamolina.edu.pe

ABSTRACT
Observations and projections for mountain regions show a strong tendency towards upslope displacement of their biomes under future climate conditions. Because of their climatic and topographic heterogeneity, a more complex response is expected for biodiversity hotspots such as tropical mountain regions. This study analyzes potential changes in the distribution of biomes in the Tropical Andes and identifies target areas for conservation. Biome distribution models were developed using logistic regressions. These models were then coupled to an ensemble of 8 global climate models to project future distribution of the Andean biomes and their uncertainties. We analysed projected changes in extent and elevational range and identified regions most prone to change. Our results show a heterogeneous response to climate change. Although the wetter biomes exhibit an upslope displacement of both the upper and the lower boundaries as expected, most dry biomes tend to show downslope expansion. Despite important losses being projected for several biomes, projections suggest that between 74.8% and 83.1% of the current total Tropical Andes will remain stable, depending on the emission scenario and time horizon. Between 3.3% and 7.6% of the study area is projected to change, mostly towards an increase in vertical structure. For the remaining area (13.1%-17.4%), there is no agreement between model projections. These results challenge the common believe that climate change will lead to an upslope displacement of biome boundaries in mountain regions. Instead, our models project diverging responses, including downslope expansion and large areas projected to remain stable. Lastly, a significant part of the area expected to change is already affected by land use changes, which has important implications for management. This, and the inclusion of a comprehensive uncertainty analysis, will help to inform conservation strategies in the Tropical Andes, and to guide similar assessments for other tropical mountains.

Show MeSH
Related in: MedlinePlus