The role of dispersal limitation and reforestation in shaping the distributional shift of a forest herb under climate change

Aim: Forest herbs might be unable to track shifts in habitat suitability
due to rapid climate change and habitat fragmentation. In this study, we
quantified the role of dispersal limitation and the potential mitigating
effect of large-scale reforestation on the redistribution of the
herbaceous forest plant species Primula elatior under climate change.
Location: Europe Methods: High resolution (100 m) landscape-scale and
macro-climatic variables were combined to predict range-wide habitat
suitability using Maxent. Dispersal limitation was modelled, based on
isolation-by-resistance (IBR) principles through integration of circuit
theory and genomic data, to assess patch accessibility and metapopulation
stability under climate change. Large scale reforestation was evaluated as
a potential mitigating strategy by incorporating a land-use change
scenario into the distribution and dispersal models. Results:
Landscape-scale variables contributed significantly to the distribution of
P. elatior (78.33%) and to the accuracy of our model (AUC=0.81).
Isolation-by-resistance (R²cond=0.92) was driven by land-use (45.5%),
distance from rivers (36.4%) and elevation (18.2%). It was estimated that
46.4±13.9% (mean±SD of climate change scenarios) of the total distribution
area would be lost due to climate change by 2050 and an additional
15.6±1.7% (mean±SD) of the distribution would not be accessible through
migration. The median latitude of the patch distribution shifted
183.2±34.8 km (mean±SD) northwards and 58.1±9.3 km (mean±SD) to more
maritime regions. The patch accessibility was low in these regions and the
metapopulation stability decreased considerably in the south of the
distribution. Reforestation mitigated 54.1±18.2% (mean±SD) of the
accessible distribution area loss and 49.5±4.2% (mean±SD) of the decrease
in metapopulation stability. Main conclusion: To alleviate the loss of the
accessible distribution area of P. elatior under climate change, it will
be required to integrate climate mitigation strategies (RCP 2.6),
range-wide afforestation, restoration of ecological connectivity and
focused assisted migration to newly available habitat.