Combining multiple models to predict the geographical distribution of the Baru tree (Dipteryx alata Vogel) in the Brazilian Cerrado

Abstract

The Brazilian Cerrado is a biome of great biodiversity, but detailed information about the diversity and distribution of species in this region is still insufficient for both testing ecological hypotheses and for conservation purposes. Among native plants in the Cerrado, Dipteryx alata Vogel (commonly known as the "Baru" tree), has a high potential for exploitation. The aims of this paper were to predict the potential spatial distribution of D. alata in the Brazilian Cerrado utilising five different niche modelling techniques. These techniques usually provide distinct results, so it may be difficult to choose amongst them. To adjust for this uncertainty, we employ an ensemble forecasting approach to predict the spatial distribution of the Baru tree. We accumulated a total of 448 occurrence points and modelled the subsequent predicted occurrences using seven climatic variables. Five different presence-only ecological niche modelling techniques (GARP, Maxent, BIOCLIM, Mahalanobis Distance and Euclidean Distance) were used and the performance of these models was compared using Receiver Operating Characteristics (ROC) and the Area Under the Curve (AUC). All models presented AUC values higher than 0.68, and GARP presented the highest AUC value, whereas Euclidean Distance presented the lowest. The ensemble forecasting approach suggested a high suitability for the occurrence of the Baru tree in the Central-Western region of the Brazilian Cerrado. Our study demonstrated that modelling species distribution using ensemble forecasting can be an important computational tool for better establishing sampling strategies and for improving our biodiversity knowledge to better identify priority areas for conservation. For the Baru tree, we recommend priority actions for conservation in the central region of the Cerrado Biome.Keywords: conservation, niche modelling, ensemble forecast, Brazilian Cerrado. Combinando múltiplos modelos para predizer a distribuição geográfica do Barueiro (Dipteryx alata Vogel) no Cerrado brasileiroResumo O Cerrado brasileiro é considerado um bioma de grande biodiversidade, no entanto, informações detalhadas sobre a diversidade e distribuição das espécies ainda é insuficiente para testar hipóteses ecológicas e para propostas de conservação biológica. Dentre as plantas do cerrado com amplo potencial de exploração, destaca-se Dipteryx alata Vogel, (vulgarmente conhecida como Barueiro). O objetivo deste trabalho foi predizer a distribuição geográfica potencial de D. alata no Cerrado brasileiro, utilizando cinco diferentes técnicas de modelagem de nicho. Essas técnicas usualmente apresentam distintos resultados, dificultando a escolha de um modelo. Para corrigir essa incerteza, usamos a estratégia de combinar os modelos gerados (ensamble forecasting) para predizer a distribuição espacial potencial do Baru. Foi acumulado um total de 448 pontos de ocorrência para as espécies e modeladas, usando sete variáveis climáticas. Foram utilizadas cinco diferentes técnicas de modelagem de nicho usando-se dados ...

Geographic shifts in climatically suitable areas and loss of genetic variability in Dipteryx alata (“Baru” Tree; Fabaceae)

“…The consensus map obtained using the ensemble forecasting approach reveals that D. alata will shift its geographic range in climatically suitable areas from Central towards Southeastern Brazil in 2050, which is a common pattern for Cerrado species (Siqueira and Peterson, 2003;Diniz-Filho et al, 2009b;Nabout et al, 2010). However, because of the wide distribution of species and the relatively homogenous climate throughout its range, even if species will be able to persist only in highly suitable regions (e.g., with occurrence frequencies above 80%), there will not be a very drastic reduction in range size, and only a few of the current local populations will be lost.…”

“…The seed (the nuts) are important for local economies, so understanding population and range dynamics under climate change may be also important for optimizing adaptive strategies for local human communities as well (e.g., Nabout et al, 2011). We used an ensemble forecast approach for obtaining species' range in which multiple SDMs and climatic models were combined (Marmion et al, 2009;Diniz-Filho et al, 2009a, 2010aNabout et al, 2010). We then obtained a series of genetic parameters (number of alleles per locus, expected heterozygosity under Hardy-Weinberg equilibrium (HWE) and mutation-drift equilibrium) for the entire species, which were recalculated assuming that local population in areas of low future environmental suitability will become extinct.…”

A performance based consensus approach for predicting spatial extent of the Chinese windmill palm ( Trachycarpus fortunei ) in New Zealand under climate change

“…Furthermore, SDMs have been used to model invasive species habitat suitability and proliferation (Roura-Pascual et al, 2008;Poulus et al, 2012;Thuiller and Richardson, 2005), recommend areas for threatened and/or endangered species (Bombi et al, 2009;Puschendorf et al, 2009) and predict distribution of native or endemic species (Evangelista et al, 2008). Similar to this effort are reports on the projection of species distribution into future conditions using global circulation models representing various climate scenarios (Nabout et al, 2010;Yates et al, 2009;Khanum et al, 2013;Chakraborty et al, 2016). We evaluated several algorithms and used the best performing ones with worldwide occurrence data to produce suitability A C C E P T E D M A N U S C R I P T 4 maps using climate datasets representing future climate change scenarios based on representative concentration pathways (RCP2.6 and 8.5) for the years 2050 and 2070.…”

Trends and biases in global scientific literature about ecological niche models

“…This high production can be explained by the higher financial investment (see Nabout et al, 2010 for an example of the influence of financial investment in the scientific production of nations) and tradition in ecological niche modeling. Nonetheless, all countries increased their scientific production over time (indicated by a positive correlation), showing an increase on this topic in several regions of the world.…”

“…Therefore, techniques for measuring the sciences, i.e., scientometrics, are useful tools to assess the quantity, quality and variety of publications on ENMs. Scientometric studies have been employed to investigate leading areas of science such as global climate change (Nabout et al, 2012b), groups of organisms (Kraan et al, 2013;Nabout et al, 2010) and genetic studies (Quixabeira et al, 2010). Studies on ENMs still lack scientometric research.…”