LOS PROCESOS DE OBJETIVACIÓN Y ANCLAJE

Our findings revealed: (i) farmland is a selective filter for uncommon species; (ii) farmland may provide habitat for reptiles, particularly if linear plantings are present; (iii) no direct association of crop harvesting with reptile responses, but interactive effects of matrix type and season, which extended across edges and deep into the adjacent remnant patches. Our findings support recommendations from recent studies to both protect remnant native

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patches of vegetation as habitat for reptiles and to continue habitat restoration in

agricultural landscapes (Attum et al. 2006, Valentine and Schwarzkopf 2009, Jellinek et al. 2014a, Pulsford et al. 2017, Lindenmayer et al. 2018).

Does reptile richness, abundance and movement differ between habitat types?

Reptile species richness and abundance, particularly uncommon species such as reptile species sensitive to soil disturbance, timber and rock removal (see Table S2; guilds classified by Michael et al. 2015), was positively associated with remnant native

vegetation and declined across the edge into open, degraded areas within the matrix (Tables S3 and S4).

This is consistent with many recent studies demonstrating remnant native vegetation is an important predictor of reptile occurrence in modified agricultural landscapes (Jellinek et al. 2014b, Pulsford et al. 2017, Michael et al. 2018). Agricultural activities alter the

fundamental structure of affected environments by removing canopy cover and exposing the ground to increased sunlight and wind, which increases surface temperature, dries microhabitats and reduces ground cover (Stoate et al. 2009b, Collins and Fahrig 2017). A direct reduction in animal abundance in response to crop management has been

demonstrated for birds (Wilson et al. 2017) and invertebrates (Thorbek and Bilde 2004, Bosem Baillod et al. 2017) but few examples are available for reptiles (Rotem et al. 2013), although see Pulsford et al. (2017) in a nearby grazing landscape. Reptiles have also been shown to be influenced by a lack of particular microhabitats (e.g. shaded leaf litter) required to avoid overheating and water loss (Pfeifer et al. 2017).

While the farmland may be a selective filter for some species and reduce the occurrence of uncommon species, we found several common, disturbance-tolerant species were present within farmland (although at lower levels of abundance), particularly when key habitat features (e.g. trees and shrubs) are present (discussed below). For reptile species adapted to hot and dry conditions, open spaces and edges, matrix environments may provide suitable habitat and favourable climatic conditions (Pfeifer et al. 2017).

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Our results indicate that efforts to increase restoration of habitat within farmland may increase reptile abundances within the matrix for some species, but do not mitigate habitat loss for edge sensitive species (Pfeifer et al. 2017) or the necessity of maintaining and increasing the extent of remnant native vegetation within these landscapes (Michael et al. 2018).

Does spatial variation in matrix quality influence reptile species richness, abundance and cross habitat movement?

We found similar numbers of reptiles from remnant patches across edges into linear plantings, compared to significantly lower abundance and richness found across edges into other matrix types (Figures 2A and 2B). Low contrast matrix types such as linear plantings likely contain more suitable resources and microclimatic conditions for patch-dependent species compared to high contrast matrix types like crop or pasture paddocks (Laurance et al. 2011, Michael et al. 2018). Linear plantings may increase movement and dispersal of birds, mammals and invertebrates (Haddad 1999, Lindenmayer et al. 2010). However, there are few studies that show plantings increase reptile numbers in the cropping matrix

(Jellinek et al. 2014a, Pulsford et al. 2017, Thompson et al. 2017). Our evidence provides a clear incentive to increase replanting efforts in agricultural landscapes (Böhm et al. 2013, Lindenmayer et al. 2016). Previous studies hypothesised that modified habitats may act as population sinks (Tilman et al. 1995, Thompson et al. 2017). Research examining

recruitment and survival are needed to determine if linear plantings are sink habitat, although we found no evidence of directional bias of movement into linear plantings. Our study represents one of the only large scale experimental studies to investigate the potential of woody mulch to attract reptiles to harvested agricultural paddocks, using a readily available material which was compatible with agricultural activities (Wanger et al. 2010, Shoo et al. 2014). Contrary to expectations (Table 1), we did not detect short-term responses to the application of fine woody debris (Figures 2A, 2B and 3). We suggest three possible explanations for the observed lack of response: (1) predation; reptiles detected and responded to debris but were removed by predators (Fischer et al. 2005); (2) reptiles

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detected the debris but the texture was too fine to provide shelter (Owens et al. 2008); (3) the material was not in-situ for long enough before surveying for reptiles to occupy these areas (Shoo et al. 2014), and; (4) woody mulch may only be used as egg-laying sites for some species. Indeed, in a previous study, we found elevated predation risk in edge habitats adjoining the woody debris matrix type, which may have contributed to avoidance behaviour or increased mortality of reptiles, subsequently reducing reptiles within the debris (Hansen unpublished data). While temporary woody mulch in cropped areas did not appear to benefit reptiles, the treatment does influence invertebrate fauna (Ng et al. 2017), and further studies could explore its value in linear plantings, where groundcover is sparse and takes a long time to develop (Cunningham et al. 2007, Smith et al. 2015).

Does the temporal influence of crop harvesting reduce matrix quality for reptiles? We predicted that crops should promote a temporary increase in prey availability for reptiles, resulting in a higher abundance and richness of reptiles within crop paddocks (Table 1), and the converse after harvesting, but this was not the case (Table 1). Instead, uncommon reptile abundance declined across the whole crop transect between harvesting periods, an effect not observed across other transects (Figure 4). These results suggest high contrast habitat edges, created by crop harvest, may contribute to edge effects for

uncommon species, influencing reptile’s responses in both the patch and matrix (Rotem 2012, Pfeifer et al. 2017). If changes in adjacent land use are increasing edge effected habitat and reducing core area of remnant patches available for reptiles, then the amount of habitat loss and fragmentation for patch-dependent species may be greater than that simply converted to agriculture (Ewers and Didham 2007, Pfeifer et al. 2017)

Previous studies have suggested cross-habitat movement of reptiles from patches into adjacent wheat fields may result in removal of those individuals by crop harvesting or increased predation (Todd et al. 2008), and subsequent reduction in the natural patches population size (Rotem et al. 2013). However, we did not find evidence of cross habitat movement of any uncommon reptile species into the paddock from the patch during or after harvest (Table S5). Survey techniques which allow direct tracking during harvesting of

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crops would be required to determine if mortality risk contributed to patterns of matrix use observed in this study.