Leaf area index of ground covers in a subtropical watershed

Xavier, Alexandre Cândido; Vettorazzi, Carlos Alberto

doi:10.1590/s0103-90162003000300002

Cited by 21 publications

(17 citation statements)

References 19 publications

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“…In January and March the areas of LAI classes were similar, also presenting equal means (LAI=1.59). This result might be associated with the high and similar precipitations and temperatures in these months, as well as, for Figure 7 -Measured Leaf Area Indices compared to predicted Leaf Area Indices using potential models (Table 4) both months, the sugar cane area presented similar LAI values due to advanced development of this crop (Xavier & Vettorazzi, 2003). LAI estimated in the watershed by LAI-NDVI models presented some areas with either higher or lower LAI values than those measured in the field campaign.…”

Section: Lai Mapping and Analysesmentioning

confidence: 73%

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Monitoring leaf area index at watershed level through NDVI from Landsat-7/ETM+ data

Xavier

Vettorazzi

2004

Sci. agric. (Piracicaba, Braz.)

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Leaf area index (LAI) is an important parameter of the vegetation canopy, and is used, for instance, to estimate evapotranspiration, an important component of the hydrological cycle. This work analyzed the relationship between LAI, measured in field, and NDVI from four dates (derived from Landsat-7/ETM+ data), and with such vegetation index, to generate and analyze LAI maps of the study area for the diverse dates. LAI data were collected monthly in the field with LAI-2000 equipment in stands of sugar cane, pasture, corn, eucalypt, and riparian forest. The relationships between LAI and NDVI were adjusted by a potential model; 57% to 72% of the NDVI variance were explained by the LAI. LAI maps generated by empirical relationships between LAI and NDVI showed reasonable precision (standard error of LAI estimate ranged from 0.42 to 0.87 m 2 m -2). The mean LAI value of each monthly LAI map was shown to be related to the total precipitation in the three previous months. Key words: biophysical variable, remote sensing, spectral vegetation indices MONITORAMENTO DO ÍNDICE DE ÁREA FOLIAR EM NÍVEL DE BACIA HIDROGRÁFICA POR MEIO DO NDVI DERIVADO DE IMAGENS LANDSAT-7/ETM+

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Section: Lai Mapping and Analysesmentioning

confidence: 73%

“…Table 1 summarizes the results of LAI field campaign for the months in which images were acquired. A complete analysis of LAI data can be seen in Xavier & Vettorazzi (2003). Figure 2 shows box-plots of LAI data for the months in which images were acquired.…”

Section: Resultsmentioning

confidence: 99%

Monitoring leaf area index at watershed level through NDVI from Landsat-7/ETM+ data

Xavier

Vettorazzi

2004

Sci. agric. (Piracicaba, Braz.)

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“…O LAI-2000 tem sido amplamente empregado em estudos de estimativa de AF e do índice de área foliar (IAF) em diferentes culturas (Sommer & Lang, 1994;Villalobos et al, 1995;Herbert & Fownes, 1997;Cutini et al, 1998;Barclay & Trofmow, 2000;Xavier et al, 2002;Xavier & Vettorazzi, 2003;Monte et al, 2007;Arias et al, 2007;Lara et al, 2011;Silva et al, 2011;Majasalmi et. al., 2012).…”

Section: Introductionunclassified

Método para estimativa do IAF de árvores isoladas ou de plantações com dossel fechado

Filho

Nova²,

Angelocci³

et al. 2012

Rev. bras. eng. agríc. ambient.

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R ESU M OObjetivou-se, com o presente trabalho, descrever e testar um método simplificado de baixo custo (IAF-LUX) para estimativa do índice de área foliar (IAF) em comparação com um equipamento comercial (LAI-2000, Li-Cor ® ). Ambos foram avaliados em um seringal e em árvores de lima ácida "Tahiti"; posteriormente, os dois métodos foram comparados com medidas destrutivas de área foliar realizadas em uma árvore adulta de lima ácida 'Tahiti'; notou-se, então, que os desvios dos resultados pelo IAF-LUX em relação aos do LAI-2000 foram no máximo de 7,4% na seringueira e de 3,6% em lima ácida "Tahiti". A estimativa da área foliar total utilizando-se o LAI 2000, mostrou boa concordância com as medidas diretas; resultados semelhantes foram obtidos com o IAF-LUX (5% de erro). Para as condições em que foi desenvolvido o trabalho os métodos com base em medida de radiação apresentaram boa precisão na estimativa da área foliar total das árvores de lima ácida, ficando patente que este método pode substituir vantajosamente as outras técnicas usadas, em comparação pelo baixo custo do equipamento, pela facilidade de operação no campo e análise dos dados. Palavras-chave: LAI-2000, luxímetro, citros, Hevea sppMethod to estimate the LAI for isolated trees and continuous canopy crops A B ST R A C T This paper aimed to describe and evaluate a low-cost simplified method (IAF-LUX method) for leaf area index (LAI) estimation, in comparison with well-tested commercial equipment (LAI-2000, Li-Cor®), being both applied for a rubber tree plantation and for a 'Tahiti' acid lime orchard. Later, the results of the both methods were also compared with destructive measurements of leaf area carried out in other 'Tahiti' acid lime adult tree. Considering LAI-2000 as reference, the proposed IAF-LUX method showed deviations of 7.4% for rubber tree and 3.6% for acid lime 'Tahiti'. Comparing the IAF-LUX with destructive measurements, a deviation of 5.0% was observed in acid lime, while LAI-2000 showed deviation of 7.0%. Based on these results, it is concluded that the IAF-LUX method may be used for determining leaf area in the two species, replacing advantageously the other destructive or non-destructive techniques because it is of low cost, easily operated and non-destructive procedure.

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“…O índice de área foliar (IAF) é um parâmetro importante na avaliação da estrutura do dossel, por caracterizar sua arquitetura e estar relacionado com a produção de biomassa vegetal (Linhares et al, 2000;Villa Nova et al, 2003;Xavier & Vettorazzi, 2003).…”

Section: Introductionunclassified

“…Dos equipamentos existentes para obtenção indireta do IAF, destaca-se o analisador de dossel LAI-2000 da LI-COR, que utiliza lentes hemisféricas (Linhares et al, 2000;Xavier et al, 2002;Almeida, 2003;Lima, 2003;Xavier & Vettorazzi, 2003;Chaves, 2005;Pezzopane et al, 2005), por sua praticidade e rapidez na obtenção dos dados, além de fornecer estimativa confiável do IAF, apesar do seu elevado custo. O princípio de uso desse aparelho consiste no balanço entre a radiação que atinge o interior do dossel e a radiação que chega ao topo do dossel, o que é determinado pelo grau de cobertura do dossel, que por sua vez é associado à densidade foliar e, conseqüentemente, ao IAF.…”

Section: Introductionunclassified

Métodos indiretos de estimação da cobertura de dossel em povoamentos de clone de eucalipto

Monte

Reis

et al. 2007

Pesq. agropec. bras.

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Resumo -O objetivo deste trabalho foi avaliar o potencial de uso de fotografias digitais na estimação do índice de cobertura de dossel (ICD), em substituição ao índice de área foliar (IAF Indirect methods to estimate canopy coverage of clonal eucalypt plantationsAbstract -The objective of this work was to evaluate methods to process digital photographs in order to estimate the canopy coverage index (CCI), to replace the use of leaf area index (LAI). Digital photographs with 640x480 and 1,280x960 pixels were processed with the Erdas Imagine, Gap Light Analyzer and Sidelook softwares. Leaf area index, using the LAI-2000, and digital photographs were obtained from pruned and thinned Eucalyptus grandis clone plantations at 81 and 93 months of age. Significant correlations were observed between LAI and CCI. Greater sized photographs (1,280x980 pixels) allowed better differentiation between sky and canopy pixels. Canopy Coverage Index obtained from digital photographs processed with the Sidelook was better correlated with LAI than that obtained by Erdas Imagine and Gap Light Analyzer. It is possible to use digital photography for eucalypt forest CCI estimation.

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Leaf area index of ground covers in a subtropical watershed

Cited by 21 publications

References 19 publications

Monitoring leaf area index at watershed level through NDVI from Landsat-7/ETM+ data

Monitoring leaf area index at watershed level through NDVI from Landsat-7/ETM+ data

Método para estimativa do IAF de árvores isoladas ou de plantações com dossel fechado

Métodos indiretos de estimação da cobertura de dossel em povoamentos de clone de eucalipto

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