Hyperspectral Monitoring of Non-Native Tropical Grasses over Phenological Seasons

Autor:	David A. Loewensteiner, Renee E. Bartolo, Timothy G. Whiteside, Andrew J. Esparon, Kirrilly Pfitzner
Rok vydání:	2021
Předmět:	Spectral shape analysis 010504 meteorology & atmospheric sciences Range (biology) Science 0211 other engineering and technologies phenological sampling 02 engineering and technology 01 natural sciences Spectral line Tropical savanna climate drones reflectance spectroscopy continuum removal Dry season 021101 geological & geomatics engineering 0105 earth and related environmental sciences Remote sensing non-native grasses Phenology Hyperspectral imaging VNIR monitoring tropical savanna General Earth and Planetary Sciences Environmental science
Zdroj:	Remote Sensing Volume 13 Issue 4 Remote Sensing, Vol 13, Iss 738, p 738 (2021)
ISSN:	2072-4292
DOI:	10.3390/rs13040738
Popis:	The miniaturisation of hyperspectral sensors for use on drones has provided an opportunity to obtain hyper temporal data that may be used to identify and monitor non-native grass species. However, a good understanding of variation in spectra for species over time is required to target such data collections. Five taxological and morphologically similar non-native grass species were hyper spectrally characterised from multitemporal spectra (17 samples over 14 months) over phenological seasons to determine their temporal spectral response. The grasses were sampled from maintained plots of homogenous non-native grass cover. A robust in situ standardised sampling method using a non-imaging field spectrometer measuring reflectance across the 350–2500 nm wavelength range was used to obtain reliable spectral replicates both within and between plots. The visible-near infrared (VNIR) to shortwave infrared (SWIR) and continuum removed spectra were utilised. The spectra were then resampled to the VNIR only range to simulate the spectral response from more affordable VNIR only hyperspectral scanners suitable to be mounted on drones. We found that species were separable compared to similar but different species. The spectral patterns were similar over time, but the spectral shape and absorption features differed between species, indicating these subtle characteristics could be used to distinguish between species. It was the late dry season and the end of the wet season that provided maximum separability of the non-native grass species sampled. Overall the VNIR-SWIR results highlighted more dissimilarity for unlike species when compared to the VNIR results alone. The SWIR is useful for discriminating species, particularly around water absorption.
Databáze:	OpenAIRE
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