Drivers of the spatial scale that best predict primate responses to landscape structure

Abstract

Understanding the effect of landscape structure on biodiversity is critically needed to improve management strategies. To accurately evaluate such effect, landscape metrics need to be assessed at the correct scale, i.e. considering the spatial extent at which species–landscape relationship is strongest (scale of effect, SE). Although SE is highly variable, its drivers are poorly known, but of key relevance to understand the way species use the landscape. In this study, we evaluate whether and how species traits, biological responses, landscape variables and the regional context of the study drive SE in Mexican primates. We estimated the relative abundance and immature‐to‐female ratio (a proxy of reproductive success) of howler monkeys Alouatta palliata and A. pigra and spider monkeys Ateles geoffroyi in 48 forest patches from four rainforest regions (12 patches per region) with different land‐use intensity. We then assessed the composition (forest cover, matrix functionality) and configuration (forest patch density, connectors’ density, forest edge density) of local landscapes considering 13 scales (100 to 1300‐m radius) to identify the spatial extent at which each landscape variable best predict each response variable in each species and region. We found that SE did not differ significantly among the drivers evaluated. However, it tended to be lower for connectors’ density than for forest patch density and forest edge density, probably because connectors’ density is associated with local‐scale processes such as supplementary dynamics. Surprisingly, SE also tended to be higher in the more disturbed region than in the rest of the regions, probably because primates in the more disturbed region used larger areas of the landscape. Our findings therefore suggest that SE depends more strongly on landscape variables and regional context than on species traits and biological responses, and hence, especial caution should be taken when attempting to generalize SE to different explanatory variables and regions.

Unraveling the scales of effect of landscape structure on primate species richness and density of titi monkeys (Callicebus nigrifrons)

“…We found two general scales of effect in this study (~1.0–2.3 km 2 and > 23 km 2 ) that may be used as a starting point for researchers interested in evaluating the impact of landscape structure on medium‐sized arboreal mammals. In fact, the smaller scale of effect is within the range of scales reported in previous studies (1.0 km 2 : Arroyo‐Rodríguez, González‐Perez, et al, ; 1.26 km 2 : Ordóñez‐Gómez et al, ; 0.98–1.58 km 2 : Galán‐Acedo et al, ). However, in half of the cases, we found scales of effect equal to the largest scale (>23 km 2 ).…”

At what spatial scale(s) do mammals respond to urbanization?

“…3), indicating these scales were not merely reflective of urban heterogeneity but rather were species-specific responses to the urban landscape (De Knegt et al 2011). These results mirror recent studies that have found a general lack of support for theoretical predictions regarding scale of effect across several taxa (Galán-Acedo et al 2018, Martin 2018, Gestich et al 2019, Moraga et al 2019, although other work has suggested that body size correlates with scale of effect in birds (Thornton and Fletcher 2014). 4, Supplementary material Appendix 4).…”

“…90%; scale 90 ). This disparity implies that the traditional focus on scale max in evaluations of scales of effect (Holland et al 2004, Galán-Acedo et al 2018, Gestich et al 2019 has likely resulted in an overall underestimation of the scale of landscape effects on wildlife (Miguet et al 2017). Miguet et al 2017).…”

A global assessment of primate responses to landscape structure

“…3). This is alarming, as an increasing number of studies demonstrate that if landscape variables are not measured at the optimal scale, species responses to landscape predictors can be poorly estimated or missed altogether, potentially leading to erroneous conclusions about the effects of landscape structure on species (Holland, Fahrig & Cappuccino, 2005;de Knegt et al, 2010;Jackson & Fahrig, 2012;Miguet et al, 2016;Galán-Acedo et al, 2018;Gestich et al, 2019).…”

“…landscape size) within which landscape variables are measured (Jackson & Fahrig, ; Miguet et al, ; Martin, ), and this has specifically been shown in primate research (e.g. Ordóñez‐Gómez et al, ; Galán‐Acedo et al, ). Significant species–landscape relationships may be undetected (i.e.…”