Methodology comparison for slope correction in canopy leaf area index estimation using hemispherical photography

Gonsamo, Alemu

doi:10.1016/j.foreco.2008.05.032

Cited by 67 publications

(37 citation statements)

References 46 publications

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“…The cameras were mounted on tripods at 1 m above ground, looking vertically upward from beneath the canopy [23]. The -levelled‖ hemispherical photographs were acquired normal to a local horizontal datum, orienting the optical axis of the lens to local zenith [24]. We measured under overcast conditions whenever possible to minimize anisotropy of the sky radiance [23].…”

Section: Ground-measurements Of Laimentioning

confidence: 99%

Validating and Linking the GIMMS Leaf Area Index (LAI3g) with Environmental Controls in Tropical Africa

et al. 2014

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Abstract:The recent Global Inventory Modeling and Mapping Studies (GIMMS) LAI3g product provides a 30-year global times-series of remotely sensed leaf area index (LAI), an essential variable in models of ecosystem process and productivity. In this study, we use a new dataset of field-based LAI True to indirectly validate the GIMMS LAI3g product, LAI avhrr , in East Africa, comparing the distribution properties of LAI avhrr across biomes and environmental gradients with those properties derived for LAI True 1974 driver. Socio-economic variables such as governance (protected areas) and population affect both LAI responses, although cause and effect are not always obvious: a positive relationship with human population pressure was detected, but shown to be an artefact of both LAI and human settlement covarying with precipitation. Despite these complexities, targeted field measurements, stratified according to both environmental and socio-economic gradients, could provide crucial data for improving satellite-derived LAI estimates, especially in the human-modified landscapes of tropical Africa.

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Section: Ground-measurements Of Laimentioning

confidence: 99%

Validating and Linking the GIMMS Leaf Area Index (LAI3g) with Environmental Controls in Tropical Africa

et al. 2014

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“…LAI is a part of the essential climate variables identified by the Global Climate Observing System (GCOS, 2006). LAI is a dimensionless value of the amount of foliage area of a vegetation canopy and is defined as one half the total radiation intercepting leaf area per unit ground horizontal surface area (Chen and Black, 1992;Gonsamo and Pellikka, 2008). The major physiological processes of vegetation including photosynthesis and evapotranspiration are determined by the vegetation biophysical parameters that describe the canopy structure as an exchange medium for energy and matter between the terrestrial ecosystem and atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Leaf area index retrieval using gap fractions obtained from high resolution satellite data: Comparisons of approaches, scales and atmospheric effects

Gonsamo¹

2010

International Journal of Applied Earth Observation and Geoinfor

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“…Such behavior can be attributed to the fact that the gap fraction method considers the foliage distribution as completely random, ignoring leaves and reproductive structures overlapped in dense cover and considering only the average image projection per unit of area on a plane normal to the zenith (Jonckheere et al, 2005;Gonsamo & Pellikka, 2008;Glatthorn & Beckschäfer, 2014).…”

Section: Resultsmentioning

confidence: 99%

Hemispherical photography to estimate biophysical variables of cotton

Brandão

Zonta

2016

Rev. bras. eng. agríc. ambient.

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A B S T R A C TThe Leaf Area Index (LAI) is a key parameter to evaluate the vegetation spectral response, estimating plant nutrition and water requirements. However, in large fields is difficult to obtain accurate data to LAI determination. Therefore, the objective of this study was the estimation of LAI, biomass and yield of irrigated cotton through digital hemispherical photography. The treatments consisted of four nitrogen doses (0, 90, 180 and 270 kg ha ). Digital hemispherical photographs were collected under similar sky brightness conditions at 60 and 75 days after emergence (DAE), performed by the Digital Plant Canopy Imager -CI-110® of CID Inc. Biomass and LAI measurements were made on the same dates. LAI was also determined by destructive and non-destructive methods through a leaf area integrator (LI-COR® -LI-3100C model), and by measurements based on the midrib length of all leaves, respectively. The results indicate that the hemispherical images were appropriate to estimate the LAI and biomass production of irrigated cotton, while for the estimation of yield, more research is needed to improve the method.Estimativa de variáveis biofísicas do algodoeiro por meio de fotografia hemisférica R E S U M O O Índice de Área Foliar (IAF) é um parâmetro essencial na avaliação da resposta espectral da vegetação e estimativa das necessidades nutricionais e hídricas das culturas, porém é difícil obter sua estimativa de forma rápida e precisa em grandes áreas. O objetivo deste estudo foi a estimativa do IAF, da biomassa aérea e da produtividade do algodoeiro irrigado por meio de fotografia hemisférica digital. O experimento consistiu de uma combinação fatorial de quatro doses de nitrogênio (0, 90, 180 e 270 kg ha -1 ) e quatro de fósforo (0, 120 e 240 e 360 kg ha -1

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Methodology comparison for slope correction in canopy leaf area index estimation using hemispherical photography

Cited by 67 publications

References 46 publications

Validating and Linking the GIMMS Leaf Area Index (LAI3g) with Environmental Controls in Tropical Africa

Validating and Linking the GIMMS Leaf Area Index (LAI3g) with Environmental Controls in Tropical Africa

Leaf area index retrieval using gap fractions obtained from high resolution satellite data: Comparisons of approaches, scales and atmospheric effects

Hemispherical photography to estimate biophysical variables of cotton

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