Rock removal associated with agricultural intensification will exacerbate the loss of reptile diversity

Abstract

1. Rocky environments host rich levels of biodiversity and provide vital habitat for specialised organisms, range-restricted species and a broad range of ectotherms adapted to saxicoline environments.2. In Australia, rock habitat is being destroyed during soil amelioration practices associated with agricultural intensification. Advances in rock crushing technology, developed to expand or increase crop yields and efficiency, pose an undocumented threat to global biodiversity, especially reptiles dependent on non-renewable rock habitat in agricultural landscapes. Rock removal is a legislated key threatening process in parts of Australia and will accelerate biodiversity loss if not mitigated.3. We estimated reptile species' range overlap with dryland cropping and modified pastoral regions within the Australian wheat-sheep zone to assess the potential impacts of rock crushing practices. We examined species-and family-richness within the impact zone and across bioregions within the impact zone, to identify areas where rock removal has the greatest potential to impact terrestrial and fossorial squamates. 4. Our analysis revealed that 159 potentially impacted reptile species occur within the study area, representing 16% of Australian terrestrial squamates. Fourteen of these species, including six threatened species, have more than 50% range overlap with areas of intensive agriculture, and include several endangered pygopodids, scincids and agamids. Bioregions rich in rock and burrow-dwelling reptiles include the Brigalow BeltSouth,

Cool shade and not‐so‐cool shade: How habitat loss may accelerate thermal stress under current and future climate

“…We focus on vegetation and rock cover, two microhabitats that offer shade cover, as well as protection from predators and competitors. First, we incorporated habitat degradation as loss of vegetation and/or rock cover, which occurs via denuding of landscape, agriculture, mining, urbanization, camping sites, trailing, and more (Michael et al, 2008, 2021; Sasaki et al, 2015; Shine et al, 1998; reviewed by Fitzsimons & Michael, 2017; Giam, 2017; Scanes, 2018). We focused our model on thermoregulation and parameterized the model by measuring the thermal conditions in six shaded desert microhabitats within the Judean Desert that varied in the size of bushes and rocks, and by recording the field and preferred body temperatures of diurnal lizards captured from these areas.…”

Rock supplementation as an ecological restoration strategy for temperate grassland reptiles

“…Intensive agriculture is increasing in many parts of Australia through technological advances, directly impacting a range of reptiles including several threatened pygopodids, scincids and agamids (Michael et al . 2021). In the ACT region, an estimated 95% of pre‐European natural temperate grassland has been destroyed or significantly altered with extensive areas of rock removal and displacement (ACT Government 2017).…”

“…However, reptile persistence in these landscapes often depends on structural habitat such as rocks (Michael et al 2008; that have progressively been removed or damaged during clearing for agricultural and urban development , recreational activities (Shlesinger & Shine 1994;Fitzsimons & Michael 2016) or collection for gardening and landscaping (Webb & Shine 2000). Intensive agriculture is increasing in many parts of Australia through technological advances, directly impacting a range of reptiles including several threatened pygopodids, scincids and agamids (Michael et al 2021). In the ACT region, an estimated 95% of pre-European natural temperate grassland has been destroyed or significantly altered with extensive areas of rock removal and displacement (ACT Government 2017).…”

Reversing habitat loss: An experimental test of the interactive effects of grazing exclusion and surface rock restoration on reptile conservation

“…Our results indicate that targeted rock restoration in areas where extensive clearing of surface rock has occurred, and cryptozoic species persist in limited remnant patches would have immediate and significant benefits for reptiles. For example, rock restoration in agricultural regions of south‐eastern Australia (Michael et al, 2021; O'Sullivan, Foster, Michael, et al, 2023) and the Mediterranean (Kazes et al, 2020), or desert shrublands in the United States (Goode et al, 2005) would be valuable to reptiles as access to rocky habitats is likely a limiting resource in these landscapes and extinction risks are high (Driscoll, 2004). Furthermore, added surface rock could act as stepping stones to connect fragmented and isolated reptile populations to improve genetic diversity and carrying capacity, increase resilience to stochastic events and reduce extinction risks (Caughley, 1994; Driscoll, 2004).…”

“…Small insular rocky outcrops and scattered surface rocks are characteristic of the landscape. However, a significant proportion of surface rocks have been picked or cleared (Michael et al, 2021), and the remaining outcrops are degraded by livestock grazing, soil erosion, weeds and pest animals such as rabbits (Michael et al, 2008).…”