A functional perspective on the analysis of land use and land cover data in ecology

Riva, Federico; Nielsen, Scott E.

doi:10.1007/s13280-020-01434-5

Cited by 23 publications

(16 citation statements)

References 57 publications

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“…To effectively conserve biodiversity, we must apply these goals at the ecoregion level, as different ecoregions house different species. Small patches are often all that remains in many human-dominated ecoregions (51,52), and our results suggest that by protecting these small patches and by restoring su cient habitat to reach total area goals (53,54) we can halt global biodiversity losses.…”

Section: Discussionmentioning

confidence: 70%

Small patches are disproportionately important for biodiversity conservation, despite ecosystem decay

Riva

Fahrig

2022

Preprint

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Positive effects of habitat patch size on biodiversity are often extrapolated to infer negative effects of habitat fragmentation on biodiversity at a landscape scale. However, such cross-scale extrapolations often fail, undermining the effectiveness of policies based on them. Forty-two percent of the manuscripts that cited a recent, landmark patch-scale analysis (Chase et al. 2020, Nature 584, 238–243) used it to infer negative fragmentation effects, despite the fact that Chase et al. cautioned against such extrapolation. We use the same dataset used by Chase et al. to test whether it is valid to extrapolate their observed patch-scale patterns to a landscape scale. We compare species diversity across many small vs. few large patches totaling the same area and sampling effort, while accounting for the patch-scale "ecosystem decay" observed in Chase et al. We find that landscape-scale patterns are opposite to their equivalent patch-scale patterns. For an equal total habitat area, species richness and evenness decrease with mean size of the patches comprising that habitat area, whether considering all species or only species of conservation concern. Thus, landscape-scale processes (e.g., turnover) enhance biodiversity across sets of many small patches despite ecosystem decay within each patch, and this is not due to incursion of generalist species into small patches. Our results confirm that patch-scale biodiversity patterns can rarely be extrapolated to a landscape scale. Most importantly, they highlight that conservation should recognize the value of small habitat patches as an important asset for preserving biodiversity worldwide.

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Section: Discussionmentioning

confidence: 70%

Small patches are disproportionately important for biodiversity conservation, despite ecosystem decay

Riva

Fahrig

2022

Preprint

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“…Differences in the structural aspects of tree and shrub proportions provide valuable insight into the land function for habitat health, livelihood resources, and ecosystem connectedness [13,14]. This study emphasized two important points: (1) the importance of critical decision points in data processing which in turn should be driven by the type of problem or question being addressed [59]; (2) identification of a set of considerations that need to be carefully weighed when selecting a remote sensing approach and classification technique for landscapes where variation in landscape composition or structural attributes impact land function.…”

Section: Discussionmentioning

confidence: 99%

“…Land function, expressed in terms of ecological and spatial vegetation heterogeneity [13], is often assessed by quantifying not only spectral measures but also the threedimensional nature of woody and herbaceous cover [14]. Estimating the relative proportion of trees, other woody vegetation, and grasses informs our understanding of key savanna ecological processes including the rate of carbon and nutrient uptake [15,16], fire intensity and duration [17], and seasonal signal response to precipitation [17].…”

Section: Introductionmentioning

confidence: 99%

Using Very-High-Resolution Multispectral Classification to Estimate Savanna Fractional Vegetation Components

et al. 2022

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Characterizing compositional and structural aspects of vegetation is critical to effectively assessing land function. When priorities are placed on ecological integrity, remotely sensed estimates of fractional vegetation components (FVCs) are useful for measuring landscape-level habitat structure and function. In this study, we address whether FVC estimates, stratified by dominant vegetation type, vary with different classification approaches applied to very-high-resolution small unoccupied aerial system (UAS)-derived imagery. Using Parrot Sequoia imagery, flown on a DJI Mavic Pro micro-quadcopter, we compare pixel- and segment-based random forest classifiers alongside a vegetation height-threshold model for characterizing the FVC in a southern African dryland savanna. Results show differences in agreement between each classification method, with the most disagreement in shrub-dominated sites. When compared to vegetation classes chosen by visual identification, the pixel-based random forest classifier had the highest overall agreement and was the only classifier not to differ significantly from the hand-delineated FVC estimation. However, when separating out woody biomass components of tree and shrub, the vegetation height-threshold performed better than both random-forest approaches. These findings underscore the utility and challenges represented by very-high-resolution multispectral UAS-derived data (~10 cm ground resolution) and their uses to estimate FVC. Semi-automated approaches statistically differ from by-hand estimation in most cases; however, we present insights for approaches that are applicable across varying vegetation types and structural conditions. Importantly, characterization of savanna land function cannot rely only on a “greenness” measure but also requires a structural vegetation component. Underscoring these insights is that the spatial heterogeneity of vegetation structure on the landscape broadly informs land management, from land allocation, wildlife habitat use, natural resource collection, and as an indicator of overall ecosystem function.

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“…Our results address another piece of the puzzle on the cumulative effects of landscape dissection from oil and gas extraction in the boreal landscape. Although total forest conversion is low in the region (~6% loss), it is the dissection of habitats by linear disturbances that has the largest potential effect on the region's biodiversity when considering their edge effects (Riva & Nielsen, 2021). And although low-impact seismic lines were designed to mitigate the negative environmental impacts of conventional seismic lines, placing them at the high densities as occurs in areas of concentrated oil-sands developments may detract from their benefits.…”

Section: Edge Interactionmentioning

confidence: 99%

“…For example, in western Canada, seismic lines — linear corridors of cleared forests (approx. 3–8 m wide) used for oil and gas exploration (Dabros et al, 2018; Lee & Boutin, 2006) — can be found at densities as high as 40 km/km 2 in some areas and edge effects are estimated to dominate the region despite the actual disturbance footprint making up only 6% of the region (Riva & Nielsen, 2021).…”

Section: Introductionmentioning

confidence: 99%

Neighboring edges: Interacting edge effects from linear disturbances in treed fens

Echiverri

Macdonald

Nielsen

2022

Applied Vegetation Science

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Questions Edge influence on forest biodiversity is an important environmental effect associated with habitat fragmentation, but extrapolating the influence of edges across the broader landscape has been difficult, especially for situations where multiple edges exist in close proximity. We asked whether there were differences in edge effects between two types (3 m vs 8 m width) of low‐severity linear disturbance (seismic lines) and whether there were interactions of edge effects when seismic lines occur in dense networks; that is, do multiple narrow seismic lines have a stronger or weaker edge influence than a single narrow seismic line. Location Treed peatlands in northeastern Alberta, Canada. Methods Seismic lines are created during oil and gas exploration and are responsible for dissection of boreal forests in western Canada. We sampled vascular plants along transects perpendicular to seismic lines in moderate‐rich and poor treed fens. We used the “Randomization Test of Edge Influence” (RTEI) to calculate the magnitude and distance of edge effects and then compared these between narrower (3 m) versus wider (8 m) lines and between single narrow lines versus multiple narrow lines (parallel and ~50 m apart). Results In moderate‐rich fens, we found a positive edge influence on understorey diversity from both wide and narrow seismic lines. We also found a weakening edge interaction on diversity, that is, single narrow seismic lines had a stronger edge influence on diversity than did multiple narrow seismic lines. In treed poor fens, multiple narrow seismic lines had a negative edge effect on tree density, understorey abundance, richness, and composition. In addition, we found strengthening edge interactions in treed poor fens on tree density, graminoid cover, and understorey composition. Conclusions Even narrow linear disturbances, such as seismic lines, can have significant edge effects and these are exacerbated when lines occur in dense networks.

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A functional perspective on the analysis of land use and land cover data in ecology

Cited by 23 publications

References 57 publications

Small patches are disproportionately important for biodiversity conservation, despite ecosystem decay

Small patches are disproportionately important for biodiversity conservation, despite ecosystem decay

Using Very-High-Resolution Multispectral Classification to Estimate Savanna Fractional Vegetation Components

Neighboring edges: Interacting edge effects from linear disturbances in treed fens

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