Earth Observation of Global Changes (EOGC)
This book provides a collection of selected articles that have been submitted to the Earth Observation and Global Changes (EOGC2011) Conference. All articles have been carefully reviewed by an international board of top-level experts. The book covers a wi
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Abstract Some invasive aquatic plants are thought to benefit from recent climate warming. Their frequent observation is only feasible using satellite data. Earlier studies used airborne hyperspectral sensors like HyMap to discriminate different plant species—this is a very cost intensive method with an environmental impact through numerous flights. A fully automated processing chain to assess the distribution of invasive species, as well as their abundances and biomass is restricted to spaceborne sensors. The research presented here investigates the ability of multi-seasonal multispectral remote sensing data (RapidEye) to differentiate between vegetated and non vegetated areas, as well as species composition at a subpixel level. This is done by combining in situ derived information about the apparent optical properties of the water body and reflectance measurements of Elodea nuttallii and Najas marina. The information about the current state of the water body is used to produce depth-invariant combinations of spectral bands using a simple physically based semiempirical method. In situ reflectance measurements were processed with the same method and subsequently used in a Matched Filtering spectral unmixing approach. The results show a good separation between vegetated and bare litoral areas. A reliable differentiation of plant species still requires further method development.
S. Roessler (&) P. Wolf T. Schneider (&) A. Melzer Limnological Institute, Technische Universität München, München, Germany e-mail: [email protected] T. Schneider e-mail: [email protected]
J. M. Krisp et al. (eds.), Earth Observation of Global Changes (EOGC), Lecture Notes in Geoinformation and Cartography, DOI: 10.1007/978-3-642-32714-8_7, Ó Springer-Verlag Berlin Heidelberg 2013
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1 Introduction Submerged macrophytes in freshwater lakes are used as longterm indicators for nutrient conditions (Melzer 1999). Climate change is thought to favour invasive submersed macrophytes in freshwater ecosystems (Rahel and Olden 2008) and therefore to have profound influence on lake ecosystems. Two invasive species, N. marina and E. nuttallii have been subject of multidisciplinary research for several years, as it is assumed that increasing water temperature promotes their expansion. N. marina is indigenous to Europe, while E. nuttallii is a neophytic species originating in North America. The species differ in their expansion speed with E. nuttallii expanding much faster. Since the trophic state of these ecosystems is strongly correlated to water temperature, adequate monitoring of these species will give important information about the development of lakes in a warming climate. In this study the application of different space—and airborne sensors for identification and monitoring of invasive aquatic plants have been tested. Until now, a frequent observation of the expansion behavior of invasive species is restricted to hyperspectral airborne remote sensing sensors which provide the needed geometric a
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