Complex effects of scale on the relationships of landscape pattern versus avian species richness and community structure in a woodland savanna mosaic

Abstract

Landscape pattern metrics are widely used for predicting habitat and species diversity. However, the relationship between landscape pattern and species diversity is typically measured at a single spatial scale, even though both landscape pattern, and species occurrence and community composition are scale‐dependent. While the effects of scale on landscape pattern are well documented, the effects of scale on the relationships between spatial pattern and species richness and composition are not well known. Here, our main goal was to quantify the effects of cartographic scale (spatial resolution and extent) on the relationships between spatial pattern and avian richness and community structure in a mosaic of grassland, woodland, and savanna in central Wisconsin. Our secondary goal was to evaluate the effectiveness of a newly developed tool for spatial pattern analysis, multiscale contextual spatial pattern analysis (MCSPA), compared to existing landscape metrics. Landscape metrics and avian species richness had quadratic, exponential, or logarithmic relationships, and these patterns were generally consistent across two spatial resolutions and six spatial extents. However, the magnitude of the relationships was affected by both resolution and extent. At the finer resolution (10‐m), edge density was consistently the best predictor of species richness, followed by an MCSPA metric that measures the standard deviation of woody cover across extents. At the coarser resolution (30‐m), NDVI was the best predictor of species richness by far, regardless of spatial extent. Another MCSPA metric that denotes the average woody cover across extents, together with percent of woody cover, were always the best predictors of variation in avian community structure. Spatial resolution and extent had varying effects on the relationships between spatial pattern and avian community structure. We therefore conclude that cartographic scale not only affects measures of landscape pattern per se, but also the relationships among spatial pattern, species richness, and community structure, often in complex ways, which reduces the efficacy of landscape metrics for predicting the richness and diversity of organisms.

Landscape structure effects on forest plant diversity at local scale: Exploring the role of spatial extent

“…Wu, 1999;Werner, 1999;Wu et al, 2000;Burnett and Blaschke, 2003;Lischke et al, 2007). Landscape metrics are known to be affected by scale, and often exhibit distinctive scaling patterns which considerably vary among metrics and habitat types (Wu et al, 2003;Wu, 2004;Bar Massada et al, 2012). Moreover, the different spatial scales at which species or communities interact with landscape structure, differentially affect key drivers of plant diversity such as vegetation dynamics (Bhar and Fahrig, 1998;Jules and Shahani, 2003;Sork and Smouse, 2006).…”

“…Many studies aimed at elucidating the relationships between landscape structure and species diversity at habitat scale, demonstrated how landscape metrics could significantly support the understanding of species diversity-environment relationships (e.g. Roy et al, 1999;Collingham et al, 2000;Bar Massada et al, 2012). However, landscape and spatial pattern metrics are heavily dependent on the multi-scalar arrangement of landscape structures (e.g.…”

Disentangling How Landscape Spatial and Temporal Heterogeneity Affects Savanna Birds

“…We found significant variability in the direction of response of individual species to both spatial and temporal variability in vegetation cover (ground and foliage projected cover). As such, the results of this study provide important support and information for more recent shifts in thinking regarding landscape-scale approaches to rangeland’s conservation management namely that: management for conservation of pattern and process should focus regimes to promote a shifting mosaic across large landscapes including highly variable and disturbed patches [52]; and complex landscape-scale effects on avian assemblage in mosaic environments are poorly understood and need more clear articulation via the use of a range of landscape metrics and tools [53].…”

“…A recent review of alternative paradigms for rangelands conservation management suggested that the focus should shift to managing landscape heterogeneity and understanding the role of shifting and mosaic disturbance regimes caused by fire and grazing [52]. The relative effects of scale on the relationships between spatial pattern and avian species richness and composition are still considered not well known [53] but are required to assess and monitor global savanna ecosystems. Remotely sensed methods of monitoring the spatio-temporal variability in woody and herbaceous vegetation, such as those used in this study, offer a potentially useful and cost-effective approach to disentangle these complex relationships [13] [53] [64].…”

Environmental heterogeneity affects the location of modelled communities along the niche–neutrality continuum

“…spatially explicit levels of aggregation across the environment, which is equivalent to spatial autocorrelation of resources [21]). Environmental heterogeneity affects many ecological patterns and processes, such as species abundance [22], species coexistence [23,24], species richness and community composition [25,26], and movement and dispersal of organisms [21,[27][28][29]. Thus, by affecting propagule flow and establishment across landscapes, environmental heterogeneity may have an important effect on the location of communities along the niche-neutrality continuum.…”