Conservation applications of niche modeling: native and naturalized ferns may compete for limited Hawaiian dryland habitat

Premise Competition from naturalized species and habitat loss are common threats to native biodiversity and may act synergistically to increase competition for decreasing habitat availability. We use Hawaiian dryland ferns as a model for the interactions between land-use change and competition from naturalized species in determining habitat availability. Methods We use fine-resolution climatic variables and carefully curated occurrence data from herbaria and community science repositories to estimate the distributions of Hawaiian dryland ferns. We quantify the degree to which naturalized ferns tend to occupy native species suitable area and map remaining available habitat given land-use change. Results Of all native species, Doryopteris angelica has the lowest percentage of occurrences of naturalized species in its suitable area while D. decora has the highest. However, all Doryopteris spp. had a higher percentage overlap—while Pellaea ternifolia had a lower percentage overlap—than expected by chance. D. decora and D. decipiens have the lowest proportions ( < 20%) of suitable area covering native habitat. Discussion Areas characterized by shared environmental preferences of native and naturalized ferns may also decrease due to human development and fallowed agricultural lands. Our study demonstrates the value of placed-based application of a recently developed correlative ecological niche modeling approach for conservation risk assessment in a rapidly changing and urbanized island ecosystem.