Using landscape context to map invasive species with medium‐resolution satellite imagery

Abstract

The spread of invasive species is a global problem of major ecological and economic concern. Landscape level assessment of invasive spread is critical, but remote sensing (RS) analyses are often complicated by the spectral similarity of species and the need to balance spatial resolution with data storage and analysis complexity. One example is the ridge and slough landscape (RSL) of the Florida Everglades, where inflowing nutrients have facilitated large‐scale cattail invasions. Hand delineation of aerial imagery has been successful in mapping cattail spread, but this technique requires considerable time and effort. Computerized classification of medium‐resolution imagery would increase the ability of scientists to provide up‐to‐date data for water management decisions. Advances in RS technologies have created opportunities that were not previously available in landscapes such as the RSL—to automatically classify sawgrass and cattail communities with medium‐resolution satellite imagery using knowledge of the invasion ecology of cattail and landscape context. We developed a computer‐classification technique that provided measure of cattail expansion that matched ground‐truthed data and show an increase in cattail area (similar to previous estimates), but a reduction in the rate of expansion over time. Although this technique can miss small patches of plants that might indicated new invasions, its rapid mapping can improve tracking of invasion fronts in the Everglades and other landscapes.

Typha (Cattail) Invasion in North American Wetlands: Biology, Regional Problems, Impacts, Ecosystem Services, and Management

“…In 2014, vegetation mapping within 63, 1-km 2 sites throughout the Everglades landscape documented that Typha alone or Typha with C. jamaicense or shrubs occurred in 60% of the sites with cover ranging from <1%, 1-5%, and 5-26% in 37, 45, and 18% of the sites, respectively. While systemwide mapping of Typha has not been conducted for over a decade, there is evidence that in some areas the rate of expansion is declining in response to reductions in P loading to the Everglades (Rutchey et al 2008;Zweig and Newman 2015). For example, in WCA-2A, the average annual rate of Typha expansion decreased from 961 ha y −1 during 1991-1995, to 312 ha y −1 during 1995-2003 (Rutchey et al 2008).…”

Assessing native desert vegetation recovery in a war‐affected area using multispectral and hyperspectral imagery: a case study of the Sabah Al‐Ahmad Nature Reserve, Kuwait

“…Remotely sensed imagery is becoming a common tool for reconstructing a site's history and detecting changes in vegetation cover (Zweig & Newman 2015;Abdullah et al 2016). Several researchers agree that remote sensing (RS) can help generate the necessary information to study the distribution of vegetation cover (Shuman & Ambrose 2003;Muthumanickam et al 2011;Im et al 2012;Peng et al 2012;Harris et al 2014) and monitor desertification (Diouf & Lambin 2001;Mollot & Bilby 2008;Malmstrom et al 2009) in arid and semi-arid lands.…”

Drones, hydraulics, and climate change: Inferring barriers to steelhead spawning migrations

“…There are numerous ways to quantify the spatial characteristics of patches on the landscape and the arrangement of the landscape—or in this instance—the river channelscape (Carbonneau et al, ; Naiman, Décamps, Pastor, & Johnston, ; Poole, ; Wiens, ; Zweig & Newman, ). Our objective was to capture the length of these hydraulic patch types in a repeatable and unbiased way while avoiding the analytical temptation of complexity analysis (e.g., McGarigal & Marks, ) and the potential pitfalls of scale‐dependent observation bias (Mandelbrot, ).…”