Remote Detection of Invasive Alien Species

Abstract

Human-mediated IAS introductions, deliberate or unintentional, tend to be much faster than natural processes (e.g., wind, animal; Theoharides and Dukes 2007; Hulme 2009; Pyšek et al. 2009; Seebens et al. 2017). Invasion pathways differ between taxa; intentional transport (escape and release) is most important for plants and vertebrates, while unintentional transport is more significant for invertebrates, algae, and microorganisms (Saul et al. 2017). Roads, tracks, and waterways create natural and artificial corridors for invasion, exposing ecosystems to invasion, particularly in emerging economies where development is rapid (Mortensen et al. 2009; Masters and Norgrove 2010). Globally, the continued expansion of tourism, air transport, and trade is dramatically heightening propagule pressure and subsequent invasion (Hulme 2015). Global environmental changes, particularly changes in climate and weather patterns, nutrient cycles, and land use, generally drive increasing invasions while also making invasion prevalence, impacts, and feedbacks to the Earth system less predictable (Bradley et al. 2010; Dukes and Mooney 1999). These same change processes can also alter IAS transport and introduction mechanisms, hindering monitoring and control (Hellmann et al. 2008; Walther et al. 2009) and making it more challenging to predict future spread. Moreover, these changes stress ecosystems and increase invasion success (Simberloff 2000). Climate and land use changes drive species range shifts, potentially creating new invasion hotspots (Bellard et al. 2013; Bradley et al. 2010) while decreasing invasion risk and increasing recovery potential in other regions (Allen and Bradley 2016). Thus, observing the geographic patterns of the spread of IAS is critical to understand their origins, pathways, and invasion processes on a changing planet.

Performance and Feasibility of Drone-Mounted Imaging Spectroscopy for Invasive Aquatic Vegetation Detection

“…RF models [41] are a popular choice for remote sensing for the classification of species from various types of imagery [1] because they have been successfully used to produce high accuracy classifications in complex environments [42][43][44]. Support vector machine algorithms (SVM) [45] are another popular classification method that has been used successfully for mapping species as well [46,47] and there is evidence suggesting that improved performance of RF or SVM over the other may be dependent on the target classes [48].…”

“…Invasive plants are a rapidly growing global concern due to their negative ecological and economic impacts. The introduction of invasive plants often results in the extinction of native plants and a reduction in biodiversity, either by outcompeting or hybridizing with native species [1][2][3]. Under most scenarios, invasive plants arrive without their co-evolved competitors or parasites allowing them to spread rapidly, replacing native plants without assuming their ecological roles.…”

“…Other governmental bodies such as the European Environmental Agency (EEA) and the United States National Invasive Species Council (NISC) are also working to improve global management capabilities. The EEA has developed indicators summarizing invasion trends and biodiversity threats and the NISC has been attempting to standardize data formats and protocol [1]. Understanding invasion origins, pathways, and processes is a key step in management and require geographic observations.…”

“…The capability to detect plant traits and species using this technology coupled with map creation is invaluable for monitoring and managing invasive plants [18]. For this reason, airborne imaging spectroscopy campaigns have become a common practice because they offer the spectral information necessary to discriminate between species sharing similar attributes [1] while having moderate to high spatial resolution needed to detect species patches.…”

Assessing the Potential Replacement of Laurel Forest by a Novel Ecosystem in the Steep Terrain of an Oceanic Island

“…Remote sensing is advancing invasion research and management by detecting and mapping invasive species, their drivers, and potential future distributions [27,28]. Differences in structural, biochemical, and physiological characteristics between species can make it possible to distinguish invasive plant species from native co-occurring vegetation by their spectral signatures [29].…”