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

Abstract

In the Anthropocene, many animal populations are increasingly confined to human‐modified landscapes, in which different spatial variables describing landscape composition and configuration influence species persistence. Forest specialist species are particularly vulnerable to these landscape disturbances. Yet, landscape effects may be undetected if assessed at the wrong spatial scale. Thus, identifying the “scale of effect”, which is the optimal spatial scale for estimating ecological responses to each landscape variable, is needed to understand the impact of landscape structure modification on species. Here, we explored the scale of effect of two compositional (forest cover and anthropogenic cover) and two configurational landscape variables (forest patch density and forest edge density) on two ecological responses: primate species richness and group densities of titi monkeys (Callicebus nigrifrons). We sampled 16 study sites in northeastern São Paulo State, Brazil. For each site, we measured each landscape variable within 10 different‐sized landscapes ranging from 0.2 to 28.3 km2 to identify the scale of effect of each landscape variable. The strength of all the primate‐landscape relationships varied across spatial scales. Although both ecological responses were most strongly associated with forest cover at the largest scale, the scale of effect of the other landscape variables differed between the response variables. These results suggest that each response variable is shaped by landscape patterns and processes operating across different spatial scales. We highlight the importance of separately assessing the scale of effect of each landscape variable on each ecological response to better understand the impact of landscape structure on species persistence.

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

“…4, Supplementary material Appendix 4). 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). Indeed, the spatial scaling of species-landscape relationships is an active area of research (Miguet et al 2016, Mertes andJetz 2018).…”

“…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).…”

Home range size scales to habitat amount and increasing fragmentation in a mobile woodland specialist

“…The scale at which landscape structure is measured is important for species persistence and can facilitate at what scales management should focus their efforts. Previous studies have suggested that the “scale effect” should vary as each spatial scale is linked to different important ecological processes (Gestich, Arroyo‐Rodríguez, Ribeiro, Cunha, & Setz, ; Jackson & Fahrig, ; Miguet, Jackson, Jackson, Martin, & Fahrig, ) and therefore is species dependent. For example, at the core range, resource acquisition and availability are important for individual survival and breeding outcomes.…”

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).…”