title: Measuring landscape-scale spread and persistence of an invaded submerged plant community from airborne remote sensing.
abstract: Processes of spread and patterns of persistence of invasive species affect species and communities in the new environment. Predicting future rates of spread is of great interest for timely management decisions, but this depends on models that rely on understanding the processes of invasion and historic observations of spread and persistence. Unfortunately, the rates of spread and patterns of persistence are difficult to model or directly observe, especially when multiple rates of spread and diverse persistence patterns may be co-occurring over the geographic distribution of the invaded ecosystem. Remote sensing systematically acquires data over large areas at fine spatial and spectral resolutions over multiple time periods that can be used to quantify spread processes and persistence patterns. We used airborne imaging spectroscopy data acquired once a year for 5 years from 2004 to 2008 to map an invaded submerged aquatic vegetation (SAV) community across 2220 km2of waterways in the Sacramento-San Joaquin River Delta, California, USA, and measured its spread rate and its persistence. Submerged aquatic vegetation covered 13-23 km2of the waterways (6-11%) every year. Yearly new growth accounted for 40-60% of the SAV area, ~50% of which survived to following year. Spread rates were overall negative and persistence decreased with time. From this dataset, we were able to identify both radial and saltatorial spread of the invaded SAV in the entire extent of the Delta over time. With both decreasing spread rate and persistence, it is possible that over time the invasion of this SAV community could decrease its ecological impact. A landscape-scale approach allows measurements of all invasion fronts and the spatial anisotropies associated with spread processes and persistence patterns, without spatial interpolation, at locations both proximate and distant to the focus of invasion at multiple points in time.
authors.affiliation: Center for Spatial Technologies and Remote Sensing (CSTARS), Department of Land, Air and Water Resources, University of California, One Shields Avenue, Davis, California, 95616, USA. m.j.ferreiradossantos@uu.nl.|Department of Innovation, Environmental and Energy Sciences, Utrecht University, Heidelberglaan 2, P.O. Box 80115, 3508 TC Utrecht, The Netherlands. m.j.ferreiradossantos@uu.nl.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Santos
authors.affiliation: Center for Spatial Technologies and Remote Sensing (CSTARS), Department of Land, Air and Water Resources, University of California, One Shields Avenue, Davis, California, 95616, USA.
authors.forename: Shruti
authors.initials: S
authors.lastname: Khanna
authors.affiliation: Center for Spatial Technologies and Remote Sensing (CSTARS), Department of Land, Air and Water Resources, University of California, One Shields Avenue, Davis, California, 95616, USA.|Department of Marine, Earth and Atmospheric Science, North Carolina State University, Raleigh, North Carolina, 27695, USA.
authors.forename: Erin L
authors.initials: EL
authors.lastname: Hestir
authors.affiliation: Center for Spatial Technologies and Remote Sensing (CSTARS), Department of Land, Air and Water Resources, University of California, One Shields Avenue, Davis, California, 95616, USA.|Department of Geography, University of Illinois, Urbana-Champaign, Illinois, 61801, USA.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Greenberg
authors.affiliation: Center for Spatial Technologies and Remote Sensing (CSTARS), Department of Land, Air and Water Resources, University of California, One Shields Avenue, Davis, California, 95616, USA.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Ustin
mesh_terms: D000220:Adaptation, Biological; D002140:California; D003710:Demography; D017753:Ecosystem; D058865:Introduced Species; D010944:Plants / Q000145:classification*; D058998:Remote Sensing Technology / Q000379:methods*; D045483:Rivers
keywords: distribution; imaging spectrometry; invasive species; remote sensing; spread and persistence; submerged aquatic vegetation