Abstract
Topographic measures are frequently used in a variety of landscape ecology applications, in their simplest form as elevation, slope, and aspect, but increasingly more complex measures are being employed. We explore terrain metric similarity with changes in scale, both grain and extent, and examine how selecting the best measures is sensitive to changes in application. There are three types of topographic measures: 1) those that relate to orientation for approximating solar input, 2) those that capture variability in terrain configuration, and 3) those that provide metrics about landform features. Many biodiversity hotspots and predators have been found to coincide with areas of complexity, yet most complexity measures cannot differentiate between terrain steepness and uneven and broken terrain. Currently characterizing terrain in landscape-level analyses can be challenging, especially at coarser spatial resolutions but developing methods that improve landscape-level assessments include multivariate approaches and the use of neighborhood statistics. Some measures are sensitive to the spatial grain of calculation, the physiography of the landscape, and the scale of application. We show which measures have the potential to be multi-collinear, and illustrate with a case study how the selection of the best measures can change depending on the question at hand using mountain lion (Puma concolor) occurrence data. The case study showed a combination of infrequently employed metrics, such as view-shed analysis and focal statistics, outperform more commonly employed singular metrics. The use of focal statistics as a measure of topographic complexity shows promise for improving how mountain lions use terrain features.
Highlights
Techniques for characterizing and quantifying land and benthic surfaces have been utilized by many biological and ecological fields of study, in addition to the fields of geomorphology, soil science, and remote sensing from which they are typically derived
Using competing models to select topographic metrics best explaining where mountain lions occur on the landscape, we found sensitivities to the scale, method of specification, and if detection-bias correction factors were used (Tables 1 and 2)
Changes in extent resulted in some metrics being more sensitive than others in how correlated they were with other metrics, but highly correlated metrics appear to be rather robust to change in physiography
Summary
Techniques for characterizing and quantifying land and benthic surfaces have been utilized by many biological and ecological fields of study, in addition to the fields of geomorphology, soil science, and remote sensing from which they are typically derived. Measures first developed for geomorphological or remote sensing applications are being applied to ecological questions, such as evaluating species’ resource selection of “rugged” terrain [2]. Topographic features can play a fundamental role in many biological, ecological, and evolutionary processes. Some features such as large mountain ranges or low elevation valleys may form barriers to movement and gene flow for some species. The American puma (Puma concolor) [4], commonly referred to as mountain lions, is unable to run long distances, and relies on saltatorial (leaping and pouncing) or scansorial (climbing) locomotion for evasion and hunting [5, 6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
