Architecture of Scots pine crown.

Ross, JJ; Kellomäki, Seppo; Oker‐Blom, Pauline; Ross, V.; Vilikainen, Ludmila

doi:10.14214/sf.a15444

Cited by 35 publications

(2 citation statements)

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“…The probable reason is that the crown shape of Scots pine tends to differ with the age of the tree. Scots pine trees are conical when young but become more rounded and irregular as they mature (Holmgren and Persson, 2004;Ross et al, 1986). Local tree competition can also influence crown shape, with the resulting more slender and conical crown (Rouvinen and Kuuluvainen, 1997) being similar to the crown shape of mountain pine.…”

Section: Discussionmentioning

confidence: 99%

Effect of slope on treetop detection using a LiDAR Canopy Height Model

Khosravipour¹,

Skidmore²,

Wang³

et al. 2015

ISPRS Journal of Photogrammetry and Remote Sensing

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Section: Discussionmentioning

confidence: 99%

Effect of slope on treetop detection using a LiDAR Canopy Height Model

Khosravipour¹,

Skidmore²,

Wang³

et al. 2015

ISPRS Journal of Photogrammetry and Remote Sensing

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“…Allometric biomass models cannot be used to estimate seasonal development of LAI, because they do not include any variables to describe for example changes in plant metabolism or the seasonal changes in SLA which is needed to convert foliage mass to LAI. Obtaining a representative SLA value remains complicated, because the SLA is influenced by canopy position, site conditions, leaf/needle age and shading (Kellomäki and Oker-Blom 1981;Ross et al 1986;Niinemets and Kull 1995;Stenberg et al 1999). Optical measurement techniques which assume optically black foliage (e.g.…”

Section: Estimation Of Ground Reference Lai and Fparmentioning

confidence: 99%

Estimation of leaf area index and the fraction of absorbed photosynthetically active radiation in a boreal forest

Majasalmi¹

2015

Diss. For.

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The aim of this dissertation is to assess the accuracy of different ground reference methods used to validate satellite based leaf area index (LAI) and the fraction of absorbed photosynthetically active radiation (fPAR) products. LAI and fPAR are strongly linked, although they principally and practically measure different properties: LAI quantifies the areal interphase between soil and atmosphere, whereas fPAR quantifies the energy available for photosynthesis. Until now, the development of remote sensing based methods to estimate LAI and fPAR in a boreal forest has been hindered by the scarcity of ground data, which is required to validate and develop existing algorithms. The aim of the first part of this dissertation was to assess the impacts of different methodological approaches to estimate LAI in boreal forests, and to validate satellite based LAI products. Results showed that the accuracy of ground based LAI estimates is sensitive to both the retrieval methods and sampling scheme used to collect the optical LAI data. The satellite based measurements of LAI demonstrated a large temporal variability in LAI. The second part of the dissertation focused on measuring and modeling fPAR in a boreal forest. A new scheme for measuring and modeling ground reference fPAR based on photon recollision probability was presented in this dissertation. Ground reference fPAR is usually estimated only for the forest canopy layer. This study is among the first ones to validate the new global satellite based fPAR product called GEOV1 using data of both the forest canopy and understory layers from boreal forests. Results showed that satellite based fPAR products may correspond better with the total fPAR, instead of only the forest canopy fPAR as has often been presumed.

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