The Biogeography of Cacti Protection and Vulnerability in South America

Abstract

Aim

The Cactaceae family is the dominant plant group in America's drylands, with many species threatened by anthropogenic factors and climate change. Here, we assessed the geographic distribution and conservation status of cacti in South America in relation to climate change.

Location

South America.

Taxon

Cactaceae.

Methods

We projected habitat suitability values for each species at current and future time periods and investigated the major drivers of species' distributions. We used these values to identify species at risk of significant range contraction (vulnerable species). We also estimated areas with exceptional habitat suitability (high-value conservation areas, HVCA) for vulnerable species in drylands, assessed the potential impacts of climate change on the spatial configuration of HVCA, and evaluated HVCA representation within protected areas.

Results

We found that temperature was the most influential factor for most species (31.5%), followed by precipitation (30.0%), indicating that climate is a major driver of cactus species distribution in the Southern hemisphere. The biogeographic distribution of HVCA for vulnerable cacti across drylands revealed that most were observed in semi-arid (41.3%) and dry sub-humid (20.9%) regions, particularly within the Brazilian Caatinga, Cerrado, and the Argentine dry Chaco. Alarmingly, 87% of these HVCA are not covered by protected areas, highlighting significant gaps, particularly evident in the Caatinga (Brazil).

Discussion

The proposed approach helps fill knowledge gaps regarding the vulnerability of cactus species to climate change and the conservation of HVCA refuges across the South American drylands. HVCA conservation can help species persist through large-scale, long-term climate change. Results show an urgent need to expand conservation efforts in HVCA to support cactus diversity, enhance our understanding of how climate change affects South American cacti, and provide crucial information to guide conservation efforts. Projected future distributions indicate that many HVCA will remain unprotected, risking significant HVCA losses unless immediate action is taken.