Oases (palm tree) and different trade routes in the Sahara Desert.

Individual oasis settlements are grouped based on their location in the same valley, depression, or region (compare S1 File: Table S1). The trade routes represent the pathways between stop-over sites (trade nodes, such as marketplaces). Trade routes are used for the transport of cargo and provide a link between producers and buyers (based on Old World Trade Routes Project: http://www.ciolek.com/owtrad.html [58]). The map shows that oases are often located along trade routes and form important trade nodes along these routes.</p

Relationships between similarity in biocultural diversity.

Relationships between similarity in biological and cultural diversity between individual oases in Algeria (different proxies given on y-axes) and their geographic distances (x-axes). Pearson correlation coefficients (r) and significance values (p) are shown.</p

S1 File -

The diversity of life sensu lato comprises both biological and cultural diversity, described as “biocultural diversity.” Similar to plant and animal species, cultures and languages are threatened by extinction. Since drylands are pivotal systems for nature and people alike, we use oases in the Sahara Desert as model systems for examining spatial patterns and trends of biocultural diversity. We identify both the underlying drivers of biodiversity and the potential proxies that are fundamental for understanding reciprocal linkages between biological and cultural diversity in oases. Using oases in Algeria as an example we test current indices describing and quantifying biocultural diversity and identify their limitations. Finally, we discuss follow-up research questions to better understand the underlying mechanisms that control the coupling and decoupling of biological and cultural diversity in oases.</div

Relationship between biological and cultural diversity and geographic distances in oases groups in Algeria.

Pearson correlation (r) and significance (p) are shown. (DOCX)</p

Correlations between (i) area, human population, and distance and (ii) biological and cultural diversity proxies on the level of (A) individual oases and (B) oasis groups in Algeria.

Correlations between (i) area, human population, and distance and (ii) biological and cultural diversity proxies on the level of (A) individual oases and (B) oasis groups in Algeria.</p

Schematic presentation of drivers and describing proxies of biocultural diversity.

Proxy groups are listed for both biological and cultural diversity (see section: Proxies for biocultural diversity in oases). Temporal change plays an overarching role as it affects environmental factors (e.g.,. climate and size of oasis), degree of connectivity, and human influences.</p