ABSTRACT
Species distribution models (SDM) are numerical tools that are used to project suitable habitat for a species. A recent study completed by Herva et al. (2016) tested the validity of an SDM developed for Lodgepole pine (Pinus contorta) in Europe. The study compared the model's projected habitat with growth performance data from 72 Pinus contorta provenance trials. The study indicated that the SDM failed in retrospectively predicting success of provenance transfers. Countries that were outside the projected habitat showed very strong Pinus contorta growth, creating uncertainty over the validity of the model.
It is possible that the SDM was correct for considering countries (such as Germany) as unsuitable habitat. While absolute growth from provenance trials may have been strong in Germany, the relative growth of Pinus contorta to other local German forestry species was not considered in the previous validity test. Relative growth is important when assessing reforestation suitability and long term success of an introduced species. I hypothesize that Pinus contorta is being outcompeted by other local tree species in areas of low SDM suitability, thus making it an undesirable choice for reforestation in Germany. Also, I hypothesize that Pinus contorta is a strong competitor relative to other local tree species in areas of high SDM suitability, such as Sweden. This hypothesis would infer that the SDM was successful in projecting potential suitable habitat for Pinus contorta in Europe facing climate change.
Growth performance data including age and mean height of Pinus contorta provenance trials and 5 other European species were compared. Pinus contorta was a strong competitor in Sweden; it was outcompeted by all other species in Germany. It can be inferred that the SDM was successful in predicting suitable habitat for Pinus contorta in Europe. This may lead to strong implications over how SDM models are being interpreted.
It is possible that the SDM was correct for considering countries (such as Germany) as unsuitable habitat. While absolute growth from provenance trials may have been strong in Germany, the relative growth of Pinus contorta to other local German forestry species was not considered in the previous validity test. Relative growth is important when assessing reforestation suitability and long term success of an introduced species. I hypothesize that Pinus contorta is being outcompeted by other local tree species in areas of low SDM suitability, thus making it an undesirable choice for reforestation in Germany. Also, I hypothesize that Pinus contorta is a strong competitor relative to other local tree species in areas of high SDM suitability, such as Sweden. This hypothesis would infer that the SDM was successful in projecting potential suitable habitat for Pinus contorta in Europe facing climate change.
Growth performance data including age and mean height of Pinus contorta provenance trials and 5 other European species were compared. Pinus contorta was a strong competitor in Sweden; it was outcompeted by all other species in Germany. It can be inferred that the SDM was successful in predicting suitable habitat for Pinus contorta in Europe. This may lead to strong implications over how SDM models are being interpreted.
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