Forest Biometrics: Definition, Tools, Methods, Uses

Forest biometrics as the name suggests consists of two words forest and biometrics.

A forest is defined as a patch of land of more than 0.5 hectares, covered by above 5 meters height of trees with canopy cover greater than 10 percent. Biometrics can be understood by breaking down as bio; relating to biology; and metric, relating to measurement.

Forest Biometrics
Forest Biometrics

Therefore, biometrics is the biological measurement and forest biometrics are measurements applied in the field of forestry. As the saying goes “whatever that cannot be measured, cannot be managed”, therefore estimating the forest resources is important for managing the forest.

Forest biometry is the application of statistical measures to assess, estimate, and evaluate the biological characteristics and processes of forests.

This incorporates forest inventory, growth and yield modeling, statistical analysis, use of LiDAR (Light Detection and Ranging), and GIS (Geographic Information System) as well. This helps in quantitative analysis of forest resources tree stands, diseases, biodiversity, ecosystem services, wildlife, etc., and serves as a guide for forest management and decision making which is important to understand the value and for growing a sustainable forest. 

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Tools used in forest biometrics

  1. Diameter tapes (D-tape) and calipers: Diameter tape shortly, D-tape is used for measuring the diameter and the circumference of a tree by wrapping the tape around the stem of the tree at a diameter at breast height (DBH) which is 1.3 meters above ground and reading the measurement on the tape. Whereas, calipers are instruments with movable arms, in between where the tree stem is placed perpendicularly at dbh and closed tightly and reading the measurement on the scale.
  2. Clinometer: It is an instrument used to measure the height of the tree based on the angle and geometry.
  3. Compass: It is an instrument used to determine the aspect (the direction in which the slope of a hill is facing) to know where the vegetation will grow well.
  4. GPS Receiver: GPS stands for Global Positioning System. It is a handheld portable instrument of the size of a mobile phone extensively used during forest inventory to obtain the latitude, longitude, and elevation and the feature to mark waypoints and save the coordinates as well. It is used to mark the coordinates of forest boundaries and to verify spatial data.
  5. Increment borer: It is a small straw-shaped instrument that goes through the bark to the center of the cores used for determining the age of the tree by measuring the annual rings. It also helps to determine the age growth rate and soundness of the tree.
  6. Remote sensing and GIS software: Remote sensing is the method of detecting and measuring the physical characteristics of the ground surface by measuring its reflected and emitted radiation whereas GIS stands for Geographic Information System. GIS uses satellite imagery to visualize spatial data and monitor the forest. It consists of several functions that help in mapping forests, knowledge on forest composition, soil health, and diseases, measuring biomass, forest fire modeling, and so on.
  7. Others: There are many emerging software nowadays that use machine learning and programming to effectively and accurately estimate chlorophyll, nitrogen, and moisture content, model forest hazards, risk assessments, forest ecology, and so on.

Methods to collect data on forest resources:

1. Forest Inventory

It is the systematic process of collecting data on various attributes of the forest such as tree dbh, height from the ground, basal area, tree grade, aspect, and slope of forest which is used to analyze and interpret available forest resources such as estimation of volume, growing stock, and yield. 

    • This information helps to monitor the forest’s condition and health. It also plays a crucial role in estimating carbon stocks and sequestration by any forest which forms a basis for carbon financing and climate change mitigation. 
    • Since it is not possible to measure every single tree in the forest, thus a sample is taken based on the accuracy needed, sample trees are measured, and the result is generalized for the whole forest.

    2. Remote sensing data

    Remote sensing is the method of detecting and measuring the physical characteristics of the ground surface by measuring its reflected and emitted radiation. Remote sensing technologies such as LiDAR, satellite imagery, aerial photography, drones, etc. can be used in combination with the ground data to determine the forest biomass, structure, health, and composition.

    a. LiDAR (Light Detection and Ranging)

    It is a type of active remote sensing (which emits its energy to illuminate the object). This technology is based on the use of laser signals to measure the distance to the Earth’s surface based on the time delay of the returned laser pulses.

    The key beneficial aspect of LiDAR is that it can penetrate through the forest canopy cover which helps to collect the three-dimensional information about tree height and density. This helps in accurately estimating forest structural characteristics such as stand volume, basal area, and above-ground biomass. 

    b. Satellite imagery

    It is the type of passive remote sensing (that uses the natural source of energy i.e. sun that illuminates the Earth’s surface). 

    Satellite imagery is images captured by satellites observing the Earth that provide information regarding the various ground features such as soil, temperature, elevation, vegetation, moisture, etc. 

    Uses of Forest Biometrics

    1. Forest management

    Forest biometrics provides crucial information on the forest resources that guide the forest manager for sustainable forest management.

      • It is important for informed decision-making about harvesting forest resources such as timber, NTFPs, biodiversity conservation, wildlife habitat protection, water resource management, etc. 

      2. Growth and Yield Prediction

      Tree growth and yield models or tables are developed from the tree stand data based on attributes such as dbh, height, and volume. 

        • A mathematical relationship model or graph is developed to show the relationship between tree dbh, height, and volume or basal area that helps to predict the growth and yield of the tree and a whole forest as well. 
        • This helps in understanding the growth rate of a forest if it is growing at a healthy rate or if the growth is declining due to factors such as diseases.
        • It also serves as a basis for preparing a work plan for the commercial purpose of harvesting timber when a tree stand has reached its optimal maturity of high volume and density. 
        • As the growth of various species differs from each other growth model of one species may not apply to other species.

        3. Carbon sequestration

        Forests play a crucial role in absorbing and storing carbon dioxide from the atmosphere that’s why it is also called carbon sinks. 

          • Carbon dioxide absorbed through photosynthesis is stored within the forests and soils which accumulates over time that contributes to the carbon stock of the forest ecosystem.
          • Forest biometrics methods such as forest inventory and remote sensing methods provide valuable information on the above-ground biomass of the tree stands from which we can calculate the carbon stock of a forest. This information is important for developing carbon financing schemes, and REDD+ implementation contributing to climate change mitigation overall.

          4. Forest Health Monitoring

          This is one of the important uses of forest biometrics. GIS-based spatial analysis and LiDAR technology provide direct measurement of the characteristics and information regarding forest diseases, site quality, forest fires, droughts, and the function and productivity of forest ecosystems essential for forest health monitoring.

          5. Biodiversity assessment

          Since forest biometrics helps to measure, assess, and quantify the forest resources, this provides insights into the diversity of tree species composition, distribution patterns, wildlife, etc. This information can contribute to making conservation plans and prioritizing the areas.


          Increasing forest values and demand for accuracy and precision in quantitative approaches have magnified the importance of forest biometrics as a tool of forestry science. Therefore it serves as a powerful tool for sustainable forest resource management and projects future outcomes of the management practices as well.

          Further Readings


          1. Arney, J. D. (2016). Biometric Methods for Forest Inventory, Forest Growth and Forest Planning. Portland, OR, Forest Biometrics Research Institute.


          About Author

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          Monika Jirel

          Monika Jirel is a final-year undergraduate forestry student at Kathmandu Forestry College, Kathmandu. As a passionate youth and a dedicated forestry student, she is interested in volunteering, advocating for climate change, and participating in youth interaction programs. The main topics of her interest are climate change, urban forestry, nature-based solutions, climate education, and biodiversity conservation. She has been engaged in organizations that work for climate change advocacy and youth mobilization, through which she has gained some experience volunteering and promoting green schools in the past few years. She enjoys writing, reading novels, and watching movies.

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