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Comparison of different ground techniques to map leaf area index of Norway spruce forest canopy


Homolová, L; Malenovský, Zbyněk; Hanuš, Jan; Tomášková, I; Dvořáková, M; Pokorný, R (2007). Comparison of different ground techniques to map leaf area index of Norway spruce forest canopy. In: ISPRS Working Group VII/1 Workshop ISPMSRS'07: "Physical Measurements and Signatures in Remote Sensing" , Davos (CH), 12 March 2007 - 14 March 2007, 499-504.

Abstract

The leaf area index (LAI) of three monocultures of Norway spruce (Picea abies (L.) Karst), different in age and structure, was measured by means of two indirect optical techniques of LAI field mapping: 1/ plant canopy analyser LAI-2000, and 2/ digital hemispherical photographs (DHP). The supportive measurements with the TRAC instrument were conducted to produce mainly the element clumping index. The aim of the study was to compare the performances of LAI-2000 and DHP and to evaluate effect of three different sampling strategies on field estimation of leaf area index. One of the suggested sampling designs introduced spatial oversampling around one-point measurement. The oversampling was expected to reveal the importance of sampling point position with respect to surrounding trees. In general, the LAI-2000 instrument produced higher estimates of effective leaf area index than DHP in all experimental stands. On the other hand, the higher "true" estimates of LAI were obtained from DHP. All three sampling strategies produced consistent estimates of effective and "true" LAI in all forest sites. The spatial oversampling of LAI measurement point did not significantly improve the LAI estimate of the canopy subplots.

Abstract

The leaf area index (LAI) of three monocultures of Norway spruce (Picea abies (L.) Karst), different in age and structure, was measured by means of two indirect optical techniques of LAI field mapping: 1/ plant canopy analyser LAI-2000, and 2/ digital hemispherical photographs (DHP). The supportive measurements with the TRAC instrument were conducted to produce mainly the element clumping index. The aim of the study was to compare the performances of LAI-2000 and DHP and to evaluate effect of three different sampling strategies on field estimation of leaf area index. One of the suggested sampling designs introduced spatial oversampling around one-point measurement. The oversampling was expected to reveal the importance of sampling point position with respect to surrounding trees. In general, the LAI-2000 instrument produced higher estimates of effective leaf area index than DHP in all experimental stands. On the other hand, the higher "true" estimates of LAI were obtained from DHP. All three sampling strategies produced consistent estimates of effective and "true" LAI in all forest sites. The spatial oversampling of LAI measurement point did not significantly improve the LAI estimate of the canopy subplots.

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Additional indexing

Item Type:Conference or Workshop Item (Paper), not refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Geography
Dewey Decimal Classification:910 Geography & travel
Language:English
Event End Date:14 March 2007
Deposited On:07 May 2013 11:18
Last Modified:14 Aug 2017 21:18
Publisher:ISPRS
Number:XXXVI7/C50
Free access at:Official URL. An embargo period may apply.
Official URL:http://www.isprs.org/proceedings/XXXVI/7-C50/papers/P95.pdf
Related URLs:http://www.isprs.org/proceedings/xxxvi/7-c50/info.pdf

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