2. Tree Crown
• The tree crown is the upper part of a tree that consists of the
branches, leaves, and reproductive structures.
• It is the part of the tree that is visible above the trunk and is
often referred to as the "canopy."
• The size, shape, and density of the crown can vary depending
on the species of the tree, its age, and its growing conditions.
• The crown plays a vital role in the tree's survival by providing
the tree with the ability to photosynthesize and produce
energy, as well as protect the tree from environmental
stressors such as wind, drought, and extreme temperatures.
• The crown is also important for ecological functions, such as
providing habitat for wildlife and contributing to the overall
biodiversity of the forest ecosystem.
Jeetendra Gautam, Agriculture and Forestry University 2
3. Importance of Crown Measurement
• Estimating tree volume: Crown measurement provides an accurate
estimation of the size and shape of the tree crown, which is used to
calculate tree volume. Accurate tree volume estimation is essential for
forest management and planning, such as predicting timber yield and
planning harvesting operations.
• Assessing forest health: The size, shape, and condition of the crown can
indicate the health status of the tree. A healthy tree will typically have a
full, symmetrical crown with uniform branching, while a tree with a small
or irregular crown may be suffering from stress, damage, or disease.
• Monitoring growth and stand dynamics: Crown measurement can be used
to track the growth and development of individual trees over time. This
information can be used to assess the overall health and productivity of the
forest stand, as well as to predict future growth and yield.
Jeetendra Gautam, Agriculture and Forestry University 3
4. Importance of Crown Measurement
• Evaluating competition: Crown measurement can help to identify
competition for resources, such as light, water, and nutrients,
between trees in the stand. This information can be used to develop
management strategies that promote the growth and productivity of
the most valuable trees.
• Planning silvicultural treatments: Crown measurement is essential
for planning silvicultural treatments, such as thinning or pruning,
which can improve the quality and value of the timber stand.
Accurate crown measurements can help to determine which trees
should be removed or pruned to achieve specific management
objectives.
Jeetendra Gautam, Agriculture and Forestry University 4
5. Methods of Crown Measurement
• Visual estimation: This involves making an
approximation of the size and shape of the crown
by eye. This method is quick and easy but may be
less accurate than other methods.
• Tape drop method: This involves dropping a
weighted tape measure from the top of the tree
and measuring the distance between the ground
and the tape measure. This measurement can be
used to estimate the height and size of the crown.
• Point sampling: This involves measuring the
distance from a fixed point to the edge of the
crown at regular intervals around the tree. These
measurements are used to calculate the average
radius and area of the crown.
Jeetendra Gautam, Agriculture and Forestry University 5
7. Methods of Crown Measurement
• Photogrammetry: This involves taking aerial
photographs of the tree and using software to create a
three-dimensional model of the crown. This method
can provide highly accurate measurements of crown
size and shape.
• LiDAR: This involves using laser technology to create a
three-dimensional model of the tree and its crown.
This method can provide highly accurate
measurements of crown size and shape, as well as
information about the structure of the tree and the
surrounding forest.
• Allometric equations: This involves using
mathematical equations to estimate the size and
shape of the crown based on measurements of other
tree characteristics, such as diameter at breast height
and height. This method is less accurate than other
methods but can be useful when direct measurements
are not feasible.
Jeetendra Gautam, Agriculture and Forestry University 7
9. Leaf area index (LAI)
• Leaf area index (LAI) is a measure of the total area of leaves in
relation to the ground surface area. It is an important parameter for
characterizing vegetation structure and function, and is commonly
used in ecological research, agriculture, and forestry.
Jeetendra Gautam, Agriculture and Forestry University 9
10. Methods for measuring LAI
• Direct measurement: This involves physically collecting and measuring all
of the leaves within a defined area. This can be time-consuming and labor-
intensive, but provides the most accurate measurement of LAI.
• Non-destructive measurement: This involves using instruments such as a
LAI-2000 plant canopy analyzer or hemispherical photography to indirectly
measure LAI without collecting or damaging the leaves. This method is less
labor-intensive but may not be as accurate as direct measurement.
• Remote sensing: This involves using satellite or aerial imagery to estimate
LAI. This method is useful for large-scale monitoring but may be less
accurate than direct or non-destructive methods.
Jeetendra Gautam, Agriculture and Forestry University 10
11. Direct measurement of LAI
• Define the measurement plot: Define a plot within the selected area, typically
1-4 m² in size. The plot size should be large enough to capture the variability of
the vegetation within the area.
• Harvest the leaves: Harvest all the leaves within the plot using a hand-held leaf
area meter or scissors. The leaves should be collected in a way that ensures
they are not damaged or crushed.
• Measure the leaf area: Measure the area of each individual leaf using a leaf
area meter or by manually tracing the outline of each leaf onto graph paper and
counting the squares. For small leaves, a leaf area meter is typically used,
whereas for larger leaves, manual tracing is more common.
Select a representative area: Choose a representative area
of the vegetation that is typical of the whole vegetation
type being studied.
Jeetendra Gautam, Agriculture and Forestry University 11
12. Direct measurement of LAI
• Calculate LAI: Calculate the LAI by summing the leaf area of all leaves
collected within the plot and dividing by the ground surface area of
the plot. The ground surface area can be calculated by measuring the
length and width of the plot and multiplying them.
• Repeat measurements: Repeat the above steps in multiple plots to
obtain a representative estimate of LAI for the entire area of interest.
Direct measurement of LAI can be time-consuming and labor-intensive,
especially for larger areas, but it provides the most accurate
measurement of LAI. It is important to ensure that the sampling design
is representative of the vegetation being studied to obtain accurate and
meaningful results.
Jeetendra Gautam, Agriculture and Forestry University 12
13. Non-destructive measurement
The LAI-2000 plant canopy analyzer is a portable device that
measures LAI by detecting the amount and distribution of
photosynthetically active radiation (PAR) within a plant canopy.
The following are the general steps involved in using the LAI-2000
plant canopy analyzer:
Set up the instrument: Set up the LAI-2000 plant canopy analyzer
according to the manufacturer's instructions. This typically
involves attaching the instrument to a tripod, connecting the
sensor head to the main unit, and calibrating the instrument.
Define the measurement plot: Define a plot within the vegetation
being studied. The plot size should be large enough to capture the
variability of the vegetation within the area.
Jeetendra Gautam, Agriculture and Forestry University 13
14. Non-destructive measurement
Take measurements: Hold the sensor head of the
LAI-2000 plant canopy analyzer at a fixed height
above the vegetation and take multiple readings
at different angles to capture the amount and
distribution of PAR within the plant canopy. The
instrument records the PAR values and calculates
the LAI.
Calculate LAI: Calculate the LAI from the PAR
readings using the software provided with the
LAI-2000 plant canopy analyzer. The software
uses algorithms to calculate the LAI based on the
PAR readings and the angle of the sensor head
Jeetendra Gautam, Agriculture and Forestry University 14
15. Using Remote Sensing to estimate LAI
• The following are the general steps involved
in using remote sensing to estimate LAI:
• Acquire satellite or aerial imagery: Acquire
satellite or aerial imagery of the area of
interest. The imagery should have sufficient
spatial resolution to capture the vegetation
structure and cover the entire area of
interest.
• Extract vegetation indices: Extract vegetation indices, such as the Normalized Difference Vegetation
Index (NDVI) or Enhanced Vegetation Index (EVI), from the imagery. Vegetation indices are mathematical
combinations of reflectance values in different spectral bands that are sensitive to the amount and
health of vegetation.
Jeetendra Gautam, Agriculture and Forestry University 15
16. Using Remote Sensing to estimate LAI
• Calibrate the vegetation indices: Calibrate the vegetation indices to
LAI using ground-based measurements of LAI. This involves
establishing a relationship between the vegetation indices and LAI
using statistical models.
• Estimate LAI: Use the calibrated vegetation indices to estimate LAI for
the entire area of interest. This can be done by applying the statistical
models to the vegetation indices for each pixel in the image.
• Validate the LAI estimates: Validate the LAI estimates by comparing
them to ground-based measurements of LAI or other independent
sources of information.
Jeetendra Gautam, Agriculture and Forestry University 16
17. Uses of Leaf Area Index (LAI)
• LAI is used to estimate crop yield and productivity by providing
information on the amount of photosynthetic area available for plant
growth and carbon assimilation.
• LAI is used to monitor the health and vitality of forests, as changes in
LAI can indicate changes in forest structure, biomass, and productivity.
• LAI is used in climate models to estimate the exchange of energy, water,
and carbon dioxide between the atmosphere and vegetation, which is
critical for understanding the global carbon cycle and climate change.
• LAI is used in hydrological models to estimate the amount of water that
is intercepted by vegetation, which is important for understanding
water balance and water availability.
Jeetendra Gautam, Agriculture and Forestry University 17
18. Uses of Leaf Area Index (LAI)
• LAI is used in ecological studies to understand the structure and
function of plant communities, including species diversity, resource
use, and competition.
• LAI is used in precision agriculture to optimize crop management
practices, such as fertilization and irrigation, by providing information
on the spatial and temporal variability of LAI within a field.
• LAI is used in remote sensing applications to estimate biophysical
variables, such as vegetation cover, biomass, and productivity, which
are important for monitoring land use and land cover changes, and
for informing natural resource management policies.
Jeetendra Gautam, Agriculture and Forestry University 18
