(INRA, 2010). Airborne and spaceborne technologies derive
LAI through transfer functions from the terrestrial data (Zheng
& Moskal, 2009). However, indirectly deriving LAI and
canopy cover metrics has limitations.
The formula to derive LAI and associated metrics from gap
fraction assumes a random distribution and angle of foliage
within a canopy. However, in the Australian context these
assumptions of deriving LAI from gap fraction are not always
met (Coops ef al., 2004). Eucalypt species commonly found in
Australia have a trait of heliotropic leaves, which breaches the
assumption that the foliage orientation is random within the
canopy (Caldas et al., 1997). These leaf traits make Australian
forest species unique to most other species found around the
world. The variety of active and passive terrestrial remote
sensing technologies indirectly measuring LAI will be used to
investigate the impact of leaf angle distribution.
There have been few studies conducted in natural forested
environments in Australia examining LAI (Coops ef al., 2004).
There is a lack of research focusing on leaf clumping and leaf
angle distribution of representative Australian vegetation using
terrestrial remote sensing technologies. Furthermore, there has
been little research undertaken in testing sampling schemes in
Australian conditions. (Hill ez al., 2006) stated that the global
MODIS LAI product could benefit from an examination of the
structural components of Eucalypt forest canopies for Australia.
The main aim of this research is to contribute to the body of
knowledge for LAI and canopy cover metrics over
representative Australian forests. Specifically, this research
looks at the level of variability among the suite of terrestrial
remote sensing instruments used to derive LAI and canopy
cover metrics in different forest conditions. The comparison of
active and passive ground based sensors will occur at two study
sites in Victoria representative of natural land systems. One
study site is representative of a dry sclerophyll forest, while the
other is a dense wet forest with a colder climate. The specific
passive instruments used for comparison were the DHP, LAI-
2200, and CI-110. The active instrument to be utilised is the
Leica Scan Station II TLS. Results reported in this study are
between the DHP and LAI-2200 over a subset of the
Rushworth sample area. The results indicate a poor correlation
for LAI derived from the in the dry sclerophyll forest.
This research is aligned with the Cooperative Research Centre
for Spatial Information's (CRC-SI) Project 2.07 (CRC-SI,
2012). The main objective of Project 2.07 is to derive woody
features and metrics at the landscape level for land managers
over representative forests for broad-scale use throughout
Australia.
This research has two longer term objectives not reported on in
this study. Firstly, to characterise both study area's variability
of LAI and cover metrics using active and passive terrestrial
sensors. Each area is to be stratified and randomly sampled at
the plot scale. Determining the plot variability will be
investigated through testing a variety of gridded and transect
based sampling strategies in order to determine the minimum
number and configuration of measurements to characterise each
metric at the plot scale. A second research aim is to use the
remotely sensed terrestrial data to validate and calibrate aerial
and satellite datasets for LAI and canopy cover metrics.
Ultimately, a validation of the MODIS LAI product will be
completed.
2. METHODS
2.1 CRC-SI Project 2.07
CRCSI Project 2.07 commenced in July 2011 and will continue
to the end of 2014. The main objective of Project 2.07 is to
delineate key woody features and metrics and derive them at
the landscape level for land managers over representative
Victorian forests. The metrics will be derived from the in situ
to site scale. This research is primarily concerned with upper
canopy metrics such as LAI and canopy cover. Three study
sites located in Victoria, Australia have been identified for
Project 2.07. Each 5x5km site was specifically chosen to be
representative of Victorian land systems. The three areas are
Rushworth, Watts Creek and Zig Zag Creek. The focus of this
research is on a subset of the Rushworth and Watts Creek study
areas.
2.2 Study Areas
Both study areas are relatively undisturbed. It is considered by
the managing agency (Department of Sustainability and
Environment, Victoria) that the public lands on which the
forests reside represent largely intact, natural and sustainable
ecosystems.
: Rushworth Forest Ref Area Ry site — s
—
Xia Zan Creek Reference Aras Research site
Watts Creek Reference Ares Research Site
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Figure 1: Location of the CRC-SI Reference Areas
Rushworth: The Rushworth Forest Reference Area (36°45’S,
144°58°E) is representative of a dry sclerophyll forest and is
located within a box-ironbark forest (Figure 1). The reference
area is part of a Box Iron Bark forest that includes several
eucalypt species such as Red Iron Bark (Eucalypytus
sideroxylon), Red Stringybark (Eucalyptus macrorhyncha),
Red Box (Eucalyptus polyanthemos), Grey Box (Eucalyptus
microcarpa) and associations. The area is dominated by the
Ecological Vegetation Class (EVC) (Woodgate et al, 1994)
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