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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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Agreement on the direction of the projected change between biome models using different climatic models.Calculations were made for scenario A1B 2010–2039 (A), A2 2010–2039 (B), A1B 2040–2069 (C) and A2 2040–2069 (D) based on physiognomy (desert, grassland, shrubland, forest) or humidity level. +++ Increasing vertical structure, ++ Either increasing vertical structure or humidity level, + Increasing humidity level, stable physiognomy, - Decreasing humidity level, stable physiognomy, -- Either decreasing vertical structure or humidity level, --- Decreasing vertical structure. Areas where less than 7 models agree on the direction of change are considered under the class “disagreement”.
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pone-0063634-g004: Agreement on the direction of the projected change between biome models using different climatic models.Calculations were made for scenario A1B 2010–2039 (A), A2 2010–2039 (B), A1B 2040–2069 (C) and A2 2040–2069 (D) based on physiognomy (desert, grassland, shrubland, forest) or humidity level. +++ Increasing vertical structure, ++ Either increasing vertical structure or humidity level, + Increasing humidity level, stable physiognomy, - Decreasing humidity level, stable physiognomy, -- Either decreasing vertical structure or humidity level, --- Decreasing vertical structure. Areas where less than 7 models agree on the direction of change are considered under the class “disagreement”.

Mentions: For the scenario A1B and period 2010–2039, in 83.1% of the total area currently occupied by Andean biomes (potential modelled map), 7 or more models project that it will remain stable and no change in biome is projected (Table 4 and Figure 4). A similar value is reported for the A2 2010–2039 scenario, though these figures are lower for the period 2040–2069. In only 3.3% (scenario A2, period 2010–2039) or 3.8% (scenario A1B, 2010–2039) of the total study area, 7 or more models effectively project a change in biome. These figures increase for period 2040–2069 to 7.6% and 7.9% for scenario A2 and A1B respectively. In the remaining areas, less than 7 out of 8 models agree on the occurrence of change (Table 4 and Figure 4).


Diverging responses of tropical Andean biomes under future climate conditions.

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

Agreement on the direction of the projected change between biome models using different climatic models.Calculations were made for scenario A1B 2010–2039 (A), A2 2010–2039 (B), A1B 2040–2069 (C) and A2 2040–2069 (D) based on physiognomy (desert, grassland, shrubland, forest) or humidity level. +++ Increasing vertical structure, ++ Either increasing vertical structure or humidity level, + Increasing humidity level, stable physiognomy, - Decreasing humidity level, stable physiognomy, -- Either decreasing vertical structure or humidity level, --- Decreasing vertical structure. Areas where less than 7 models agree on the direction of change are considered under the class “disagreement”.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0063634-g004: Agreement on the direction of the projected change between biome models using different climatic models.Calculations were made for scenario A1B 2010–2039 (A), A2 2010–2039 (B), A1B 2040–2069 (C) and A2 2040–2069 (D) based on physiognomy (desert, grassland, shrubland, forest) or humidity level. +++ Increasing vertical structure, ++ Either increasing vertical structure or humidity level, + Increasing humidity level, stable physiognomy, - Decreasing humidity level, stable physiognomy, -- Either decreasing vertical structure or humidity level, --- Decreasing vertical structure. Areas where less than 7 models agree on the direction of change are considered under the class “disagreement”.
Mentions: For the scenario A1B and period 2010–2039, in 83.1% of the total area currently occupied by Andean biomes (potential modelled map), 7 or more models project that it will remain stable and no change in biome is projected (Table 4 and Figure 4). A similar value is reported for the A2 2010–2039 scenario, though these figures are lower for the period 2040–2069. In only 3.3% (scenario A2, period 2010–2039) or 3.8% (scenario A1B, 2010–2039) of the total study area, 7 or more models effectively project a change in biome. These figures increase for period 2040–2069 to 7.6% and 7.9% for scenario A2 and A1B respectively. In the remaining areas, less than 7 out of 8 models agree on the occurrence of change (Table 4 and Figure 4).

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