Canopy properties estimation in deciduous forests with digital photography
Author(s)
Chianucci, Francesco
Date Issued
June 17, 2013
Type
Doctoral Thesis
Abstract
Rapid, reliable and meaningful estimates of forest canopies are essential to the characterization of
forest ecosystems. The aim of the research was to conduct a thorough technical appraisal of existing
available digital photographic methods for forest canopy estimation. The more traditionally used
digital hemispherical photography (DHP), which measures the gap fraction at multiple zenith
angles, was compared with methods that measure the gap fraction at a single zenith angle, namely
57° photography and cover photography (DCP). DCP is a more recent canopy photographic
method, which measures gap fraction at the zenith (0°).
These methods were applied in deciduous forests of beech, chestnut and Turkey oak. All
photographic methods provided good indirect estimates of canopy properties, as compared with
reference direct methods obtained by littertraps and AccuPAR ceptometers. However, all methods
showed different advantages and disadvantages, which were discussed and addressed.
Among the methods, DCP showed high potential as a means to quickly obtain inexpensive
estimates of forest canopy over large areas, being therefore highly suitable for routine, research and
monitoring of forest canopy attributes. The method also appeared particularly suitable for
calibrating nadir remotely-sensed canopy estimates, on account of its high vertical resolution
imagery.
Comparison of logarithm gap fraction averaging procedures implied in DHP allowed
defining a protocol for effective leaf area index and apparent clumping index extraction from non
segmented analysis of gap fraction, which can be applied to both DHP and LAI-2000 PCA. The
results have important implications for the evaluation of satellite-based leaf area index product of
airborne laser scanning (LiDAR).
Comparisons of compact (point-and-shoot) cameras with digital single lens reflex cameras
allowed defining standardized field protocol for image acquisition and software analysis. The
outcome can greatly assist canopy photographic methods to achieve the standards of an ideal
device.
The study also provided a suite of several variables of interest such as light extinction
coefficient and crown porosity, which can provide insights towards the characterization of
deciduous forests, and which can be further applied for further canopy studies in deciduous stands.
Additional information
Dottorato di ricerca in Ecologia forestale
File(s)![Thumbnail Image]()
Name
fchianucci_tesid.pdf
Size
2.28 MB
Format
Adobe PDF
Checksum (MD5)
4502c98a068e94445064195cb1a500ba