Estimation of canopy gap size and gap shape using a hemispherical photograph

Hu, Lile; Gong, Zhijun; Li, Junsheng; Zhu, Jiaojun

doi:10.1007/s00468-009-0353-9

Cited by 16 publications

(13 citation statements)

References 35 publications

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“…1b) 1.0 m above the ground by using a Nikon Coolpix 995 fitted with an FC-E8 fisheye lens. The lens was set to a small aperture and focused on infinity (Frazer et al 2001;Hu et al 2009). The tops of photographs were oriented towards magnetic north (Hu et al 2009).…”

Section: Gap Monitoringmentioning

confidence: 99%

“…The lens was set to a small aperture and focused on infinity (Frazer et al 2001;Hu et al 2009). The tops of photographs were oriented towards magnetic north (Hu et al 2009). Images were recorded in 2048 × 1536 pixels, the highest resolution setting possible on the camera.…”

Section: Gap Monitoringmentioning

confidence: 99%

“…First, hemispherical photograph method (HPM) (Hu et al 2009) was used to calculate canopy gap size. We positioned one point of each border tree's crown (P c ) where the distance is nearest to the center of the images, and recorded its coordinate (in pixels) by using Adobe Photoshop CS2 software.…”

Section: Photograph Analysismentioning

confidence: 99%

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Gap closure process by lateral extension growth of canopy trees and its effect on woody species regeneration in a temperate secondary forest, Northeast China

Lu¹,

Zhu²,

Sun³

et al. 2015

Silva Fenn.

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G. (2015). Gap closure process by lateral extension growth of canopy trees and its effect on woody species regeneration in a temperate secondary forest, Northeast China. Silva Fennica vol. 49 no. 5 article id 1310. 17 p. Highlights• Gap closure process by lateral extension growth can be described by quadratic functions.• Large gaps (514-621 m 2 ) had higher closure rates but lower closure percentages compared with middle (174-321 m 2 ) and small gaps (68-125 m 2 ).• Gaps promoted woody species regeneration in early stage.• Large and middle gaps would provide opportunities for filling regeneration, but regeneration in small gaps may eventually fail. AbstractGap formation and its effects on regeneration have been reported as being important in forest development, but seldom studies concentrated on the gap closure process by lateral extension growth of canopy trees surrounding gaps. We monitored the closure process of 12 artificial gaps for 7 years with three size classes: small (from 68 m 2 to 125 m 2 ), middle (from 174 m 2 to 321 m 2 ), and large (from 514 m 2 to 621 m 2 ); and investigated the regeneration twice in a temperate secondary forest, Northeast China. The closure process can be described through quadratic functions, which showed the closure rates slowed down with gap ages. Large gaps had a higher closure rate (39 m 2 a -1 ) than middle gaps (25 m 2 a -1 ) and small gaps (11 m 2 a -1 ). According to the quadratic equations, the lateral growth could last 11, 13 and 16 years for small, middle and large gaps with a remaining size of 12, 69 and 223 m 2 , respectively. As expected, regeneration exhibited the highest seedling density and volume in large gaps. There was no significant difference in regeneration density between middle gaps, small gaps and forest understory in the final investigation; but the volume of regenerated woody species increased significantly from small gaps to large gaps compared with forest understory. These results may provide references on the choice of appropriate gap sizes to promote the regeneration in temperate secondary forests.

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Section: Gap Monitoringmentioning

confidence: 99%

Section: Gap Monitoringmentioning

confidence: 99%

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Gap closure process by lateral extension growth of canopy trees and its effect on woody species regeneration in a temperate secondary forest, Northeast China

Lu¹,

Zhu²,

Sun³

et al. 2015

Silva Fenn.

Self Cite

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“…Various methods for estimating gap parameters have been proposed and used (Runkle, 1981;Brokaw, 1982;Yamamoto, 1989;Hu et al, 2009). There are two major ways of surveying gaps: ground survey (Runkle, 1981;Yamamoto, 1989) and using aerial photographs (Nakashizuka et al, 1995;Fujita et al, 2003a;Itaya et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

A comparison of different survey methods for assessing gap parameters in old-growth forests

Yamamoto

Nishimura

Torimaru

et al. 2011

Forest Ecology and Management

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“…A partir de esas mediciones es posible estimar estructura y transmisión de luz al sotobosque (Rich, 1990;Hu et al, 2009), ambas de gran importancia para el inventario forestal (Chen et al, 2006;Cruz-leyva et al, 2010) y el manejo de la regeneración natural (Yamamoto, 2000;Yamamoto et al, 2011).…”

Section: Introductionunclassified

Introducción a la fotografía hemisférica en ciencias forestales

Mauro-Díaz

Lencinas

Valle

2014

MYB

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La fotografía hemisférica es profusamente utilizada en climatología y ciencias forestales en vinculación con tecnología geomática. Permite obtener un registro detallado de los claros del dosel y estimar, tanto la estructura del mismo, como la transmisión de luz al sotobosque, ambas variables de gran importancia para el inventario forestal y el manejo de la regeneración natural. Debido a que los equipos de fotografía hemisférica tienen usos muy diversos, incluso en fotografía artística, su costo es bajo en comparación con instrumentos específicos. Para utilizar esta técnica correctamente se requiere de conocimientos particulares de óptica, fotografía y procesamiento digital de imágenes. El objetivo del trabajo es explicar el principio de funcionamiento de la fotografía hemisférica en estimación de parámetros estructurales de bosques. Para ello se discute sobre óptica y fotografía, procesamiento digital de imágenes y estimación de parámetros estructurales. Conocer estos aspectos es relevante para adquirir un equipo, capturar fotografías en el terreno y utilizar softwares específicos para su procesamiento. Las fotografías son archivos raster, los cuales pueden entenderse como una matriz de n filas por m columnas, donde cada celda es un pixel. Para que un raster se visualice como una imagen es necesario establecer un espacio y una profundidad de color. Es importante tener en cuenta que en la captura de la fotografía se producen muchos errores, ya que dependiendo de la región geográfica es muy difícil satisfacer las condiciones ideales de iluminación.

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Estimation of canopy gap size and gap shape using a hemispherical photograph

Cited by 16 publications

References 35 publications

Gap closure process by lateral extension growth of canopy trees and its effect on woody species regeneration in a temperate secondary forest, Northeast China

Gap closure process by lateral extension growth of canopy trees and its effect on woody species regeneration in a temperate secondary forest, Northeast China

A comparison of different survey methods for assessing gap parameters in old-growth forests

Introducción a la fotografía hemisférica en ciencias forestales

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