491
18.4 Shifting of the Natural Range of Forest Tree Species
Associated to Climate Change Forecast
Distributional shifts in tree species populations are already taking place (Lloyd et al.
2011; Fisichelli et al. 2013; Boisvert-Marsh et al. 2014). However, uncertainty
remains about the ability of trees to effectively colonize new habitats in pace with a
rapidly changing climate, particularly in light of widespread habitat fragmentation
due to agriculture expansion and urbanization (Hampe et al. 2013; Alfaro et al.
2014). In fact, failure of trees to track climate warming, especially at the sapling
stage, warns about the ability of forests to surpass global change (Sittaro et al.
2017). Although there are controversies about the reasons for these distributional
changes (Máliš et al. 2016), the concern is general.
We present here two studies carried out in Argentina as examples of the possible
effect of the climate change on the natural distribution of forest tree species.
Example 1: Range Prediction Through Ecological Niche Modeling
In Argentina Nothofagus forests are constrained to a narrow longitudinal area determined by the rain shadow effect of the Andes Mountain range. To the east, there is
a transition to steppe vegetation, and particularly this transitional zone between
Patagonian forest and steppe is expected to undergo rapid and pronounced shifts in
distribution and species composition as a consequence of projected climate change
(Allen and Breshears 1998; Suarez and Kitzberger 2010). Climatic models predicted that the precipitation gradient would become sharper due to expected drops
in rainfall (Castañeda and González 2008; Barros et al. 2015) and increases in
extreme climatic events, like severe droughts (Rusticucci and Barrucand 2004).
Therefore, current distribution ranges might be compromised.
Ecological niche modeling (ENM) is a useful tool to investigate about potential
distribution patterns of species. This approach is based on relating known occurrences
of species to landscape level variation in environmental parameters of importance to
species’ distribution ecology, providing models of inferred environmental requirements
(Peterson 2006; Waltari et al. 2007). By reconstructing future (2050s) habitat suitability
scenarios of N. alpina and N. obliqua, the possible shifts on their current distribution
ranges was investigated (Marchelli et al. 2017). As both species have sympatric distributions, but occupy differential niches along the precipitation gradient, owing to their
inherent temperature and hydric tolerances, they can serve as a model for gauging the
expected impact of climate change on the eastern Patagonian forests. Suitability mapping was based on ensembles of modeling of 11 algorithms (for details see Marchelli
et al. 2017). For characterizing future climate conditions, 19 and 31 downscaled climate
models for the period 2040–2069 based on the SRES-A2 scenario of greenhouse gas
emissions, obtained from CMIP5, were used (Ramirez-Villegas and Jarvis 2010).
The modeling approach showed that N. alpina might be impacted more severely
by climate change than N. obliqua. No single area in Argentina exists where all future
climate model projections unanimously predict habitat suitability by the 2050s for
N. alpina. Only a very tiny fraction of its current distribution is expected to remain
suitable according to at least half of all future climate model projections (Fig. 18.3).
18 Questions, Perspectives and Final Considerations of Planting Native Species…
18.4 Shifting of the Natural Range of Forest Tree Species
Associated to Climate Change Forecast
Distributional shifts in tree species populations are already taking place (Lloyd et al.
2011; Fisichelli et al. 2013; Boisvert-Marsh et al. 2014). However, uncertainty
remains about the ability of trees to effectively colonize new habitats in pace with a
rapidly changing climate, particularly in light of widespread habitat fragmentation
due to agriculture expansion and urbanization (Hampe et al. 2013; Alfaro et al.
2014). In fact, failure of trees to track climate warming, especially at the sapling
stage, warns about the ability of forests to surpass global change (Sittaro et al.
2017). Although there are controversies about the reasons for these distributional
changes (Máliš et al. 2016), the concern is general.
We present here two studies carried out in Argentina as examples of the possible
effect of the climate change on the natural distribution of forest tree species.
Example 1: Range Prediction Through Ecological Niche Modeling
In Argentina Nothofagus forests are constrained to a narrow longitudinal area determined by the rain shadow effect of the Andes Mountain range. To the east, there is
a transition to steppe vegetation, and particularly this transitional zone between
Patagonian forest and steppe is expected to undergo rapid and pronounced shifts in
distribution and species composition as a consequence of projected climate change
(Allen and Breshears 1998; Suarez and Kitzberger 2010). Climatic models predicted that the precipitation gradient would become sharper due to expected drops
in rainfall (Castañeda and González 2008; Barros et al. 2015) and increases in
extreme climatic events, like severe droughts (Rusticucci and Barrucand 2004).
Therefore, current distribution ranges might be compromised.
Ecological niche modeling (ENM) is a useful tool to investigate about potential
distribution patterns of species. This approach is based on relating known occurrences
of species to landscape level variation in environmental parameters of importance to
species’ distribution ecology, providing models of inferred environmental requirements
(Peterson 2006; Waltari et al. 2007). By reconstructing future (2050s) habitat suitability
scenarios of N. alpina and N. obliqua, the possible shifts on their current distribution
ranges was investigated (Marchelli et al. 2017). As both species have sympatric distributions, but occupy differential niches along the precipitation gradient, owing to their
inherent temperature and hydric tolerances, they can serve as a model for gauging the
expected impact of climate change on the eastern Patagonian forests. Suitability mapping was based on ensembles of modeling of 11 algorithms (for details see Marchelli
et al. 2017). For characterizing future climate conditions, 19 and 31 downscaled climate
models for the period 2040–2069 based on the SRES-A2 scenario of greenhouse gas
emissions, obtained from CMIP5, were used (Ramirez-Villegas and Jarvis 2010).
The modeling approach showed that N. alpina might be impacted more severely
by climate change than N. obliqua. No single area in Argentina exists where all future
climate model projections unanimously predict habitat suitability by the 2050s for
N. alpina. Only a very tiny fraction of its current distribution is expected to remain
suitable according to at least half of all future climate model projections (Fig. 18.3).
18 Questions, Perspectives and Final Considerations of Planting Native Species…