Combining conservation status and species distribution models for planning assisted colonisation under climate change

Abstract

Effects of climate change are particularly important in the Mediterranean Biodiversity hotspot where rising temperatures and drought are negatively affecting several plant taxa, including endemic species. Assisted colonisation (AC) represents a useful tool for reducing the effect of climate change on endemic plant species threatened by climate change. We combined species distribution models (SDMs) for 188 taxa endemic to Italy with the IUCN red listing range loss threshold under criterion A (30%) to define: (a) the number of AC (measured as 2 × 2 km grid cells that should be occupied by new populations, i.e. grid cells = new populations) required to fully compensate for predicted range loss and to halt the decline below the 30% of range loss; (b) The number of cells necessary to compensate for range loss was calculated as the number of currently occupied cells lost under future climate due to unsuitable conditions. We used two representative concentration pathways, +2.6 and +8.5 W/m2, optimistic and pessimistic scenarios respectively. Availability of suitable areas for AC was also assessed within the current species distribution and within protected areas. Under the optimistic scenario, no taxa would lose more than 30% of their range and AC would not be required. Under the pessimistic scenario, roughly the 90% of taxa showed a cell loss higher than 30%. Eight taxa were predicted to lose >95% of their range. For these species, AC was required from 13 to 16 new populations (=13–16 grid cells) per taxon to cap the range loss at 30%. For currently VU or EN species, an average number of 32–35 AC attempts would be necessary to fully compensate their range loss under a pessimistic scenario. Suitable recipient sites within protected areas falling in their projected range were identified, allowing for short‐distance AC. Synthesis. Combining species distribution models and red listing thresholds under Criterion A has enabled the strategic planning of multiple species assisted colonisation minimising the effort in terms of new populations to be created and maximising the conservation benefit in terms of range loss compensation.

Data-integration of opportunistic species observations into hierarchical modeling frameworks improves spatial predictions for urban red squirrels

“…Although urban sprawl is among the main drivers of habitat loss and degradation, cities also offer suitable habitat islands (Angold et al, 2006;Niesner et al, 2021) and can function as stepping stones (Saura et al, 2014;Lynch, 2019), if functional connectivity -exchange of genes, biomass or energy -is prevailing (Baker and Harris, 2007;Braaker et al, 2014). However, urban wildlife faces increasing challenges due to growing anthropogenic pressure and predicting the distribution of species in anthropogenic areas is therefore a crucial factor for urban wildlife conservation and should build the basis for urban planning (Fajardo et al, 2014;Casazza et al, 2021). Species distribution models (SDMs) quantify the relationship between observations of a species and the underlying environmental gradients (Araújo and Guisan, 2006;Guisan et al, 2017), and they encompass occupancy frameworks, machine-learning algorithms and hierarchical modeling frameworks (Elith and Leathwick, 2009;Kéry et al, 2010;Dorazio, 2014;Hefley and Hooten, 2016).…”

Ecological niche modeling, niche overlap, and good old Rabinowitz’s rarities applied to the conservation of gymnosperms in a global biodiversity hotspot

“…Araucaria forest) (Donoso 2006, Luebert andPliscoff 2006), here we showed that each species can also harbor its particular set of environmental constrains. This species-specific set of constrains might be relevant to guide climate change mitigation projects through assisted migration programs for focal species in this hotspot (Casazza et al 2021). This strategy can be especially relevant for endemic species that might not be able to follow rapid changes in climate, as they may have little dispersal capacity (Essl et al, 2011), and/or a reduced climatic niche, so negative effects of warming and climate change deepen their survival (Ozinga et al 2009), particularly for cold tolerant species.…”

Exploring the potential for plant translocations to adapt to a warming world

“…The term translocation has typically been used in the context of reintroduction whereby a population of a threatened species is Whereas Casazza et al (2021) found that translocation of narrow endemics might involve just a handful of sites to offset climate losses, we expect that dominant tree species threatened within their range (e.g. coast redwood) would have to be translocated at a landscape level to protect overall habitat, ecosystem productivity and associated species.…”

“…For each species, they calculated the number of translocation attempts needed to compensate for declines in climatically suitable habitat within the historical limits of a species geographical range. Under optimistic climate change scenarios, range losses for all species were below the threshold of 30% reduction—the range loss required to change a Red List categorisation from Least Concern to Vulnerable (Casazza et al., 2021). This suggested that none of the 188 species required translocation to avoid a recognised deterioration in conservation status by 2080.…”

“…disease). In forestry, 'assisted migration' is viewed more favourably as a practice capable of matching planted tree populations to future climates.In this Special Focus,Casazza et al (2021) use a dataset of 188 endemic Italian species to assess the need for translocation under projected climate change scenarios. For each species, they calculated the number of translocation attempts needed to compensate for declines in climatically suitable habitat within the historical limits of a species geographical range.…”