Conservation benefits of international Aichi protection and restoration targets for future epiphyte metapopulations.
More than half way towards the deadline for 2020 Aichi targets, a key question is whether the metapopulation dynamics of dispersal-restricted habitat specialists can be sustained under current international targets of protection and restoration. We present the first metapopulation projections under scenarios of multiple Aichi biodiversity targets of protecting high-quality habitats and restoring suboptimal quality habitats under management. We simulate 200 years of metapopulation dynamics of nine old-growth beech (Fagus sylvatica)-associated epiphytic lichens, under a range of protection and restoration scenarios in a realistic landscape realm. Protection was generally more efficient than restoration, where protection resulted in a constant increase in occupancy over time. However, projections showed that substantial increments in the number of occupied protected beech stands will most likely occur within the next 100-200 years. The time frame was dependent on species-specific dispersal restriction, occupancy levels at onset and forest-age requirements. Suboptimally restored beech stands increased lichen metapopulation sizes over a transient period and shortened the time for dispersal-restricted species to reach higher occupancy levels inside protected areas of the landscape (c. 85-125 years). Synthesis and applications. Based on projections of metapopulation dynamics of species associated with old-growth forest, we argue that a combination of protection and restoration with the shortest possible time frame for increasing occupancy is the safest strategy. This is especially important under climatic and socio-political changes that are unforeseeable over centuries. If choosing between conservation strategies, highest priority should be given to increased protection because it means larger metapopulation sizes of these species on the long term.