Field Determination of Optimal Dates for the Discrimination of Invasive Wetland Plant Species Using Derivative Spectral Analysis

Laba, Magdeline; Tsai, Fuan; Ogurcak, Danielle E.; Smith, Stephen D.; Richmond, Milo E.

doi:10.14358/pers.71.5.603

Cited by 44 publications

(28 citation statements)

References 22 publications

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“…Because the actual spectral resolution of the spectrometer is ~3 nm, we resampled the field spectra by averaging reflectance at every three nanometer increments into one value, similar to the way in which the aircraft sensor sampled spectra. The first derivative of reflectance, a transformation which has been shown to be useful for extracting biophysical information from spectral curves [28,31], was calculated in the spectral region of 562-600 nm. This spectral region has a subtle absorption feature (Figure 3a) sensitive to leaf chlorophyll concentration [51,52], and leaf chlorophyll concentration has been demonstrated to be linked with foliar nitrogen more or less [20,21,53,54].…”

Section: Spectral Reflectance Indices Calculation-field-collected Spementioning

confidence: 99%

“…These methods include: (1) use of the first derivative of the spectral reflectance curve and (2) continuum removal [28][29][30]. The first derivative of reflectance characterizes the changes of the original reflectance by which the background effects are countervailed [31]. Continuum removal provides a common baseline that allows the spectral features to be standardized and compared [21,32].…”

Section: Introductionmentioning

confidence: 99%

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Estimating Canopy Nitrogen Content in a Heterogeneous Grassland with Varying Fire and Grazing Treatments: Konza Prairie, Kansas, USA

et al. 2014

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Quantitative, spatially explicit estimates of canopy nitrogen are essential for understanding the structure and function of natural and managed ecosystems. Methods for extracting nitrogen estimates via hyperspectral remote sensing have been an active area of research. Much of this research has been conducted either in the laboratory, or in relatively uniform canopies such as crops. Efforts to assess the feasibility of the use of hyperspectral analysis in heterogeneous canopies with diverse plant species and canopy structures have been less extensive. In this study, we use in situ and aircraft hyperspectral data to assess several empirical methods for extracting canopy nitrogen from a tallgrass prairie with varying fire and grazing treatments. The remote sensing data were collected four times between May and September in 2011, and were then coupled with the field-measured leaf nitrogen levels for empirical modeling of canopy nitrogen content based on first derivatives, continuum-removed reflectance and ratio-based indices in the 562-600 nm range. Results indicated that the best-performing model type varied between in situ and aircraft data in different months. However, models from the pooled samples over the growing season with acceptable accuracy suggested that these methods are robust with respect to canopy heterogeneity across spatial and temporal scales.

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Section: Spectral Reflectance Indices Calculation-field-collected Spementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Estimating Canopy Nitrogen Content in a Heterogeneous Grassland with Varying Fire and Grazing Treatments: Konza Prairie, Kansas, USA

et al. 2014

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“…Detecting a specific plant species in forests, rangelands, riparian areas and natural landscapes using remote sensing techniques has proved to be a greater challenge. Large-scale infestations, where invaders are clearly the dominant species and environmental heterogeneity is reduced, tend to be easier to detect remotely [3,8,9].…”

Section: Introductionmentioning

confidence: 99%

Mapping Invasive Tamarisk (Tamarix): A Comparison of Single-Scene and Time-Series Analyses of Remotely Sensed Data

et al. 2009

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Abstract:In this study, we tested the Maximum Entropy model (Maxent) for its application and performance in remotely sensing invasive Tamarix sp. Six Landsat 7 ETM+ satellite scenes and a suite of vegetation indices at different times of the growing season were selected for our study area along the Arkansas River in Colorado. Satellite scenes were selected for April, May, June, August, September, and October and tested in single-scene and time-series analyses. The best model was a time-series analysis fit with all spectral variables, which had an AUC = 0.96, overall accuracy = 0.90, and Kappa = 0.79. The top predictor variables were June tasselled cap wetness, September tasselled cap wetness, and October band 3. A second time-series analysis, where the variables that were highly correlated and demonstrated low predictive strengths were removed, was the second best model. The third best model was the October single-scene analysis. Our results may prove to be an effective approach for mapping Tamarix sp., which has been a challenge for resource managers. Of equal importance is the positive performance of the Maxent model in handling remotely sensed datasets.

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“…Pigment absorption features are detected in the second derivative spectra as derivative peaks where peak centers correspond to the maximum absorption wavelengths of the pigment responsible for that particular peak. Second derivative spectra were calculated as previously detailed [23].…”

Section: Derivative Analysismentioning

confidence: 99%

Biomass and Community Structure of Epilithic Biofilm on the Yellow and East Coasts of Korea

Kim¹,

Park²,

Heo³

et al. 2014

OJMS

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Spatial biomass variation and community structure of epilithic biofilms were examined using cell counts, chlorophyll a extraction, and remote-sensing techniques. Samples were collected at two levels of wave exposure along the Yellow and East Coasts of Korea in December 2010. Cyanobacteria were dominant, occupying about 88% of biofilm, irrespective of wave exposure levels. The cyanobacteria species, Aphanotece spp. was abundant in the Yellow Coast location and Lyngbya spp. was abundant in the East coast location. The representative diatoms were Navicula spp. and Achnanthes spp. on the rocky shores of all study sites. Average Normalized Difference Vegetation Index (NDVI) was significantly greater in the Yellow Coast (mean 0.46) than that in the East Coast (mean 0.21); a similar pattern was observed in Vegetation Index (VI). Chlorophyll a content was three times greater on the Yellow Coast (20.50 μg/cm 2 ) than that on the East Coast (8.21 μg/cm 2 ), and it was greater at the Gosapo and Bangpo shore sites than that at the Gyeokpo site, on the Yellow Coast. However, chlorophyll a contents were not different between 23.33 and 17.66 μg/cm 2 at exposed-and sheltered-shores of Yellow Coast, and were 9.62 μg/cm 2 and 6.80 μg/cm 2 on the East Coast. Vegetation indices were positively correlated with chlorophyll a contents. In conclusion, biofilm of Korean upper rocky shore was mainly composed of cyanobacteria and biofilm biomass that differed between the Yellow and East Coast.

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Field Determination of Optimal Dates for the Discrimination of Invasive Wetland Plant Species Using Derivative Spectral Analysis

Cited by 44 publications

References 22 publications

Estimating Canopy Nitrogen Content in a Heterogeneous Grassland with Varying Fire and Grazing Treatments: Konza Prairie, Kansas, USA

Estimating Canopy Nitrogen Content in a Heterogeneous Grassland with Varying Fire and Grazing Treatments: Konza Prairie, Kansas, USA

Mapping Invasive Tamarisk (Tamarix): A Comparison of Single-Scene and Time-Series Analyses of Remotely Sensed Data

Biomass and Community Structure of Epilithic Biofilm on the Yellow and East Coasts of Korea

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