Remote sensing of submerged vegetation canopies for biomass estimation

Armstrong, Roy A.

doi:10.1080/01431169308904363

Cited by 119 publications

(74 citation statements)

References 5 publications

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“…The model is limited to wavelengths from 400 nm to 700 nm and to sun zenith angles from 25 • to 65 • . Due to strong absorption of water in the near-infrared wavelengths the characteristic spectral features normally are superimposed by water absorption [41]. Hence, several surface models of reflectance intensities could be processed for each sun zenith angle.…”

Section: Reflectance Modelmentioning

confidence: 99%

“…At the beginning of the growing season, the spectral response, even of sparsely vegetated areas, is sediment-dominated. Organic material on the lake bottom such as epiphytes and detritus may alter the spectral response of bare sediment [6,13,[39][40][41]. During the growing season, changes in macrophyte/sediment coverage ratio, leaf size and orientation, leaf pigment concentrations and cellular structure specifically influence intensity and shape of spectral signatures [6,13,40].…”

Section: Introductionmentioning

confidence: 99%

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Seasonal Variation in Spectral Response of Submerged Aquatic Macrophytes: A Case Study at Lake Starnberg (Germany)

Fritz

Schneider

Geist

2017

Water

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Submerged macrophytes are important structural components of freshwater ecosystems that are widely used as long-term bioindicators for the trophic state of freshwater lakes. Climate change and related rising water temperatures are suspected to affect macrophyte growth and species composition as well as the length of the growing season. Alternative to the traditional ground-based monitoring methods, remote sensing is expected to provide fast and effective tools to map submerged macrophytes at short intervals and over large areas. This study analyses interrelations between spectral signature, plant phenology and the length of growing season as influenced by the variable water temperature. During the growing seasons of 2011 and 2015, remote sensing reflectance spectra of macrophytes and sediment were collected systematically in-situ with hyperspectral underwater spectroradiometer at Lake Starnberg, Germany. The established spectral libraries were used to develop reflectance models. The combination of spectral information and phenologic characteristics allows the development of a phenologic fingerprint for each macrophyte species. By inversion, the reflectance models deliver day and daytime specific spectral signatures of the macrophyte populations. The subsequent classification processing chain allowed distinguishing species-specific macrophyte growth at different phenologic stages. The analysis of spectral signatures within the phenologic development indicates that the invasive species Elodea nuttallii is less affected by water temperature oscillations than the native species Chara spp. and Potamogeton perfoliatus.

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Section: Reflectance Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Seasonal Variation in Spectral Response of Submerged Aquatic Macrophytes: A Case Study at Lake Starnberg (Germany)

Fritz

Schneider

Geist

2017

Water

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“…Due to strong attenuation of water in near-infrared wavelengths ( Figure 2) this feature is normally superimposed by water absorption [23]. To minimize the influence of water absorption, ( ) was included in the index calculation.…”

Section: Differentiation Of Littoral Bottom Coveragementioning

confidence: 99%

“…In particular, Y 3,4 covered a characteristic vegetation feature, the red edge, i.e., the passage where reflectance strongly increases between visible red and near infrared wavelengths. Due to strong attenuation of water in near-infrared wavelengths ( Figure 2) this feature is normally superimposed by water absorption [23]. To minimize the influence of water absorption, K d (λ) was included in the index calculation.…”

Section: Differentiation Of Littoral Bottom Coveragementioning

confidence: 99%

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Mapping Submerged Aquatic Vegetation Using RapidEye Satellite Data: The Example of Lake Kummerow (Germany)

Fritz

Dörnhöfer

Schneider

et al. 2017

Water

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Submersed aquatic vegetation (SAV) is sensitive to changes in environmental conditions and plays an important role as a long-term indictor for the trophic state of freshwater lakes. Variations in water level height, nutrient condition, light availability and water temperature affect the growth and species composition of SAV. Detailed information about seasonal variations in littoral bottom coverage are still unknown, although these effects are expected to mask climate change-related long-term changes, as derived by snapshots of standard monitoring methods included in the European Water Framework Directive. Remote sensing offers concepts to map SAV quickly, within large areas, and at short intervals. This study analyses the potential of a semi-empirical method to map littoral bottom coverage by a multi-seasonal approach. Depth-invariant indices were calculated for four Atmospheric & Topographic Correction (ATCOR2) atmospheric corrected RapidEye data sets acquired at Lake Kummerow, Germany, between June and August 2015. RapidEye data evaluation was supported by in situ measurements of the diffuse attenuation coefficient of the water column and bottom reflectance. The processing chain was able to differentiate between SAV and sandy sediment. The successive increase of SAV coverage from June to August was correctly monitored. Comparisons with in situ and Google Earth imagery revealed medium accuracies (kappa coefficient = 0.61, overall accuracy = 72.2%). The analysed time series further revealed how water constituents and temporary surface phenomena such as sun glint or algal blooms influence the identification success of lake bottom substrates. An abundant algal bloom biased the interpretability of shallow water substrate such that a differentiation of sediments and SAV patches failed completely. Despite the documented limitations, mapping of SAV using RapidEye seems possible, even in eutrophic lakes.

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A visual assessment technique for estimating seagrass standing crop

Mumby

Edwards

Green

et al. 1997

Aquatic Conserv: Mar. Freshw. Ecosyst.

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1. Ground‐truthing techniques for measuring seagrass standing crop need to be simple, precise, non‐destructive and quick. 2. Mellors (1991) designed a visual assessment technique for estimating above‐ground seagrass biomass. This paper builds on Mellors' work and presents a modified method for estimating standing crop which uses a six‐point ordinal scale (excluding zero). 3. Being non‐destructive, this technique is ideally suited for resource assessment in environmentally sensitive areas and, being quick, is potentially useful when threats are imminent. 4. Statistical methods and data presented in this study will allow sample size/statistical power relationships to be estimated for any comparable study and therefore negate the need to conduct pilot surveys. © 1997 John Wiley & Sons, Ltd.

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Remote sensing of submerged vegetation canopies for biomass estimation

Cited by 119 publications

References 5 publications

Seasonal Variation in Spectral Response of Submerged Aquatic Macrophytes: A Case Study at Lake Starnberg (Germany)

Seasonal Variation in Spectral Response of Submerged Aquatic Macrophytes: A Case Study at Lake Starnberg (Germany)

Mapping Submerged Aquatic Vegetation Using RapidEye Satellite Data: The Example of Lake Kummerow (Germany)

A visual assessment technique for estimating seagrass standing crop

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