Shifted distribution baselines: neglecting long-term biodiversity records risks overlooking potentially suitable habitat for conservation management

Abstract

Setting appropriate conservation measures to halt the loss of biodiversity requires a good understanding of species' habitat requirements and potential distribution. Recent (past few decades) ecological data are typically used to estimate and understand species’ ecological niches. However, historical local extinctions may have truncated species–environment relationships, resulting in a biased perception of species' habitat preferences. This may result in incorrect assessments of the area potentially available for their conservation. Incorporating long-term (centuries-old) occurrence records with recent records may provide better information on species–environment relationships and improve the modelling and understanding of habitat suitability. We test whether neglecting long-term occurrence records leads to an underestimation of species’ historical niche and potential distribution and identify which species are more vulnerable to this effect. We compare outputs of species distribution models and niche hypervolumes built using recent records only with those built using both recent and long-term (post-1500) records, for a set of 34 large mammal species in South Africa. We find that, while using recent records only is adequate for some species, adding historical records in the analyses impacts estimates of the niche and habitat suitability for 12 species (34%) in our dataset, and that this effect is significantly higher for carnivores. These results show that neglecting long-term biodiversity records in spatial analyses risks misunderstanding, and generally underestimating, species' niches, which in turn may lead to ill-informed management decisions, with significant implications for the effectiveness of conservation efforts. This article is part of a discussion meeting issue ‘The past is a foreign country: how much can the fossil record actually inform conservation?’

Using recent baselines as benchmarks for megafauna restoration places an unfair burden on the Global South

“…For example, while Pleistocene rewilding can be met with criticism (Rubenstein et al 2006, Oliveira-Santos andFernandez 2010), this long-term perspective is useful to provide context for future-oriented restoration initiatives, for informing on the potential for biodiversity (in contrast to more degraded Holocene time points) and for informing on the factors that have been key for generating and maintaining biodiversity in the long-term (Svenning 2020). Holocene baselines also provide invaluable insights into species' ecology, climatic tolerance and habitat preferences that are often not available from recent records only (Monsarrat et al 2019).…”

“…However, these baselines are biased with a Eurocentric perspective that overlooks variations in the timing of human impacts across the world (Sanderson 2019), which can lead to arbitrary and potentially unfair restoration. For megafauna species, extinctions in the Late Pleistocene and early Holocene 50 000 to 7 000 years ago -mostly concentrated in the Americas and Australia, and to a lesser extent in Eurasia (Stuart 2015, Smith et al 2018) -as well as historical (Monsarrat et al 2019, Teng et al 2020 and recent declines (Ripple et al 2015(Ripple et al , 2016 have heavily reshaped global distribution patterns (Faurby and Svenning 2015). Hence, considering current, relictual, patterns of distribution risks hindering our understanding of optimal habitat for species (Kerley et al 2020), underestimating areas where it could be restored (Monsarrat et al 2019), and ultimately leading to less ambitious restoration objectives (Balmford 1999).…”

The Protected Area Paradox and refugee species: The giant panda and baselines shifted towards conserving species in marginal habitats

“…The first, and perhaps biggest, challenge is to overcome the shifted baselines of conservation managers and scientists. Monsarrat, Novellie, Rushworth, and Kerley (2019) recently showed that neglecting historical range data underestimates conservation opportunities, ecological niches and habitat usage for species, and that this is relatively common (34% of their admittedly small sample of 34 large mammal species) and biased towards carnivores. These shifted baselines hinder the critical assessment of current conservation efforts, and the exploration of alternative approaches, this through the identification of optimal habitats and testing hypotheses around refugee species status, following the process outlined by Kerley et al (2012).…”

Anthropocene refugia: integrating history and predictive modelling to assess the space available for biodiversity in a human-dominated world

“…Niche truncation caused by past local extirpations biases our understanding of natural habitat-species relationships. By underestimating the extent of potential suitable habitat, this can affect our understanding of areas available for conservation today [20] and provide unreliable forecasts of distribution changes under future climate change [21]. This case of shifted baseline can be avoided by incorporating prehistoric and historical data on the taxon's occurrence into estimates of potential distribution.…”