Data from: Rarity, geography, and plant exposure to global change in the California Floristic Province

Aim: Rarity and geographic aspects of species distributions
mediate their vulnerability to global change. We explore the relationships
between species rarity and geography and their exposure to climate and
land use change in a biodiversity hotspot. Location: California,
USA. Taxa: One hundred and six terrestrial plants.
Methods: We estimated four rarity traits: range size, niche
breadth, number of habitat patches, and patch isolation; and three
geographic traits: mean elevation, topographic heterogeneity, and distance
to coast. We used species distribution models to measure species
exposure—predicted change in continuous habitat suitability within
currently occupied habitat—under climate and land use change scenarios.
Using regression models, decision-tree models and variance partitioning,
we assessed the relationships between species rarity, geography, and
exposure to climate and land use change. Results: Rarity,
geography and greenhouse gas emissions scenario explained >35% of
variance in climate change exposure and >61% for land use change
exposure. While rarity traits (range size and number of habitat patches)
were most important for explaining species exposure to climate change,
geographic traits (elevation and topographic heterogeneity) were more
strongly associated with species' exposure to land use change. Main
conclusions: Species with restricted range sizes and low
topographic heterogeneity across their distributions were predicted to be
the most exposed to climate change, while species at low elevations were
the most exposed to habitat loss via land use change. However, even some
broadly distributed species were projected to lose >70% of their
currently suitable habitat due to climate and land use change if they are
in geographically vulnerable areas, emphasizing the need to consider both
species rarity traits and geography in vulnerability assessments.