Doctoral defence: Bruno Paganeli "Dark diversity methods for prioritization of areas and species in nature conservation"

On November 15 at 10:15 Bruno Paganeli will defend his doctoral thesis "Dark diversity methods for prioritization of areas and species in nature conservation" for obtaining the degree of Doctor of Philosophy (in Botany and Mycology).

Supervisor:
Professor Meelis Pärtel, University of Tartu

Opponent:
Professor Javier Loidi, Euskal Herriko Unibertsitatea (University of the Basque Country, Spain)

Summary:
Human activities are fragmenting landscapes and introducing non-native species, leading to biodiversity loss worldwide. My thesis addresses those processes through the concept of dark diversity – the set of absent but ecologically suitable species in a given site. This approach provides a more holistic view of biodiversity since it considers its potential.

Although dark diversity is unobservable, multiple methods are available to estimate its size and composition. Based on my research, the current most efficient method is based on pairwise species co-occurrences, which stems from the fact that species which exist side-by-side also share ecological requirements. We can “ask” present species with which other species they generally co-occur. I applied this framework to assess nature conservation issues on different scales in time and space, from a square meter to a global extent.

In Estonia's old-growth forests, we found that surrounding forest availability influences local biodiversity, and dark diversity can reveal these patterns better than observed diversity. I found that epiphytes were especially strongly dependent on surrounding ancient forests. In addition, I combined species traits with dark diversity to infer why some species are often absent from suitable sites or, in contrast, tend to spread widely.

Dark diversity was an extremely valuable framework within biological invasion research, allowing us to estimate possible non-native species before they actually arrive. I explored the observed and dark diversity of non-native plants worldwide and identified species that are more likely to invade new regions in the future.

My thesis demonstrates that the use of dark diversity is valuable across various nature conservation contexts, allowing preventive actions that are typically easier to implement and more cost-effective than solving situations later, both from ecological and economic perspectives.

Minu väitekiri näitab, et tumeda elurikkuse käsitlus pakub uudset teavet erinevates looduskaitselistes küsimustes. See võimaldab kasutada ennetavaid meetmeid ökosüsteemide ja liikide kaitseks, mida on tavaliselt lihtsam rakendada ja mis on nii ökoloogilisest kui ka majanduslikust vaatenurgast kulutõhusamad kui tagajärgede likvideerimine.