Abstract
Boosted Regression Trees (BRT) is one of the modelling techniques most recently applied to biodiversity conservation and it can be implemented with presence-only data through the generation of artificial absences (pseudo-absences). In this paper, three pseudo-absences generation techniques are compared, namely the generation of pseudo-absences within target-group background (TGB), testing both the weighted (WTGB) and unweighted (UTGB) scheme, and the generation at random (RDM), evaluating their performance and applicability in distribution modelling and species conservation. The choice of the target group fell on amphibians, because of their rapid decline worldwide and the frequent lack of guidelines for conservation strategies and regional-scale planning, which instead could be provided through an appropriate implementation of SDMs. Bufo bufo, Salamandrina perspicillata and Triturus carnifex were considered as target species, in order to perform our analysis with species having different ecological and distributional characteristics. The study area is the “Gran Sasso—Monti della Laga” National Park, which hosts 15 Natura 2000 sites and represents one of the most important biodiversity hotspots in Europe. Our results show that the model calibration ameliorates when using the target-group based pseudo-absences compared to the random ones, especially when applying the WTGB. Contrarily, model discrimination did not significantly vary in a consistent way among the three approaches with respect to the tree target species. Both WTGB and RDM clearly isolate the highly contributing variables, supplying many relevant indications for species conservation actions. Moreover, the assessment of pairwise variable interactions and their three-dimensional visualization further increase the amount of useful information for protected areas’ managers. Finally, we suggest the use of RDM as an admissible alternative when it is not possible to individuate a suitable set of species as a representative target-group from which the pseudo-absences can be generated.
Highlights
In conservation biology, one of the most important activities is monitoring population abundances and distribution, both for animals and plants
Many conservationists celebrate the expansion of protected territories and the increasing attention paid to biodiversity, but they often disagree on how to manage parks and reserves
With regard to UTGB and WTGB, we considered the values of AUC and deviance within each of the ten cross-validation folds in the final optimized model (n = 10 for each metric for both methods), while for the RDM approach we considered the mean cross-validated AUC and deviance values for each of the four replicates performed (n = 4 for each metric)
Summary
One of the most important activities is monitoring population abundances and distribution, both for animals and plants. Studying changes over time in an animal distribution means understanding its temporal dynamics, assessing management effectiveness [1]. As reported by Marsh and Trenham [2], there are many different monitoring techniques to evaluate animal population dynamics, and the data obtained can be used to identify endangered species or real and potential diffusion of invasive and pest species [3,4,5,6]. The development of several modelling approaches has allowed ecologists to better understand the potential diffusion of animals and plants and predict their distribution within changing environmental scenarios [7], and this represents a promising tool in biodiversity conservation issues
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
