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A Comparison of the Signal from Diverse Optical Sensors for Monitoring Alpine Grassland Dynamics

Rossi, Mattia and Niedrist, Georg and Asam, Sarah and Tonon, Giustino and Tomelleri, Enrico and Zebisch, Marc (2019) A Comparison of the Signal from Diverse Optical Sensors for Monitoring Alpine Grassland Dynamics. Remote Sensing, 11 (296), pp. 1-22. Multidisciplinary Digital Publishing Institute (MDPI). DOI: 10.3390/rs11030296 ISSN 2072-4292

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Official URL: https://www.mdpi.com/2072-4292/11/3/296/htm

Abstract

Grasslands cover up to 40% of the mountain areas globally and 23% of the European Alps and affect numerous key ecological processes. An increasing number of optical sensors offer a great opportunity to monitor and address dynamic changes in the growth and status of grassland vegetation due to climatic and anthropogenic influences. Vegetation indices (VI) calculated from optical sensor data are a powerful tool in analyzing vegetation dynamics. However, different sensors have their own characteristics, advantages, and challenges in monitoring vegetation over space and time that require special attention when compared to or combined with each other. We used the Normalized Difference Vegetation Index (NDVI) derived from handheld spectrometers, station-based Spectral Reflectance Sensors (SRS), and Phenocams as well as the spaceborne Sentinel-2 Multispectral Instrument (MSI) for assessing growth and dynamic changes in four alpine meadows. We analyzed the similarity of the NDVI on diverse spatial scales and to what extent grassland dynamics of alpine meadows can be detected. We found that NDVI across all sensors traces the growing phases of the vegetation although we experienced a notable variability in NDVI signals among sensors and differences among the sites and plots. We noticed differences in signal saturation, sensor specific offsets, and in the detectability of short-term events. These NDVI inconsistencies depended on sensor-specific spatial and spectral resolutions and acquisition geometries, as well as on grassland management activities and vegetation growth during the year. We demonstrated that the combination of multiple-sensors enhanced the possibility for detecting short-term dynamic changes throughout the year for each of the stations. The presented findings are relevant for building and evaluating a combined sensor approach for consistent vegetation monitoring.

Item URL in elib:https://elib.dlr.de/129321/
Document Type:Article
Title:A Comparison of the Signal from Diverse Optical Sensors for Monitoring Alpine Grassland Dynamics
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Rossi, Mattiamattia.rossi (at) eurac.eduUNSPECIFIED
Niedrist, Georggeorg.niedrist (at) eurac.eduUNSPECIFIED
Asam, Sarahsarah.asam (at) dlr.dehttps://orcid.org/0000-0002-7302-6813
Tonon, Giustinogiustino.tonon (at) unibz.itUNSPECIFIED
Tomelleri, Enricoenrico.tomelleri (at) unibz.itUNSPECIFIED
Zebisch, Marcmarc.zebisch (at) eurac.eduUNSPECIFIED
Date:1 February 2019
Journal or Publication Title:Remote Sensing
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:No
Volume:11
DOI :10.3390/rs11030296
Page Range:pp. 1-22
Publisher:Multidisciplinary Digital Publishing Institute (MDPI)
ISSN:2072-4292
Status:Published
Keywords:Grassland dynamics; alpine grassland; Sentinel-2 MSI; Spectroradiometer; Phenocam; Spectral Reflectance Sensors; multiscale; multisensor; NDVI
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Erdbeobachtung
DLR - Research theme (Project):R - Remote sensing and geoscience
Location: Oberpfaffenhofen
Institutes and Institutions:German Remote Sensing Data Center > Land Surface Dynamics
Deposited By: Asam, Dr. Sarah
Deposited On:07 Oct 2019 11:31
Last Modified:21 Nov 2019 05:05

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