Lecture 9 - Measuring and Monitoring Forest Resources Flashcards
Why measure forest resources?
- to take stock/inventory of what is in the forest for forest management, conservation, or general interest
What is forest mensuration/biometrics?
A branch of forest management that focuses on techniques for efficient/effective measurement of forests
What are the primary forest products?
- saw logs (high value): veneer/lumber 8ft or longer
- bolts (lower value): short logs <8ft
- chips (low value/waste): small pieces of wood that are byproducts of cutting up logs & sawmill waste; they can be raw materials for a variety of products or used for fuel
What is scaling in terms of measuring primary forest products?
It measures the physical quality of forest products in units of board foot content.
- several different measurements were developed (called log rules) that are inaccurate and since more accurate ones have been developed
What are the different classes of grading based on quality?
- Veneer: high quality, used for furniture, includes factory lumber grade 1
- Factory: boards in which defects can be removed and provide good quality wood, includes factory lumber grades 2 and 3
- Construction: logs are reduced in size and are good enough for construction
- Local-Use: don’t meet standard specifications, like strength and durability, so they’re used for industrial purposes (ex. pallets)
Why locate and measure land area using land surveying and mapping?
- to delineate forest properties and forest stands for timber
- to locate roads, streams, and sample plots
What are the typical measurements for measuring land area?
- distance
- direction
- land surveys
- forest type
How is distance determined?
There are several methods.
- Pacing: not accurate, but can be done by one person; must calibrate individual pace using natural walking gait to determine the length of one pace
- Tape measure: more accurate, requires 2 people
- Electronic/optical instrument: most accurate, requires line of sight free from obstructions
How is direction determined?
- magnet compasses are usually preferred by foresters b/c they’re easy to use, efficient, and low cost
- GPS units are often used as well, which are also accurate
How is a land survey done?
- rectangular survey system uses established baselines (running east to west) and meridians (running north to south) where an intersection of a baseline and meridian is an initial point
How is DBH measured/used?
- measure 1.3m above ground on the uphill side of a tree
- can use a: tree diameter tape measures circumference and automatically converts to DBH; or tree caliper
- DBH is converted to basal area (BA), which is the cross-section of a tree at breast height
How is tree height determined?
- can climb the tree and drop measuring tape
- height poles (for shorter trees)
- geometry (basic math)
- hypsometer (electronically measures height)
What are merchantable products?
- products of trees that are used to market/sell
- uses measurements of parts of trees that can be sold
What is merchantable height? How is it measured?
- it is the usable portion of a tree
- it is measured 1’ above stump to height where the diameter becomes too small
What is destructive sampling?
- a method for measuring volume & tree mass (rarely allowed to do this)
- trees are cut down and all tree components are measured/weighed
- used for research purposes and develop alometric equations
- equations are then calibrated with dbh and height measurements and applied to other forests to avoid future destructive sampling
What is non-destructive sampling?
- a method for measuring volume & tree mass (more common)
- trees are not allowed to be cut down, so estimations of volume & mass are made using height and dbh
- optical dendrometers can also be used to measure diameter over various tree heights & is often more accurate
What is tree age?
It is the amount of time elapsed since seed germination
How do annual growth rings work in varying climates?
Temperate climates: summer & winter growth rings
Tropical climates: dry and wet season growth rings (dark lines winter/dry season growth and light lines summer/wet season growth)
What is an increment corer? How is it used?
- used to find tree age of living tree
- twist it into the tree, take out the core, and count rings to determine age
- software and C14 dating could also be used but they are very expensive
What is forest sampling?
Instead of measuring every tree on a property, a subset of trees representative of the forest stand used for measurements is used, known as forest sampling.
- circular or rectangular plots are selected within a stand and are randomly or systematically chosen in which all trees in that plot will then be measured
What are permanent sample plots used for?
- reveal insight into the dynamics of a forest stand
- ex. new trees emerge that were not previously measured (aka ingrowth); trees have died since last sample; trees harvested can be identified
What are the components of measuring forest growth?
- site quality
- stocking/density
- growth and yield projection
What is site quality?
The productive capacity of a specific area of forestland of a specific tree species - some species will grow better on one site than another will due to soil quality, climate, and topography
What is a site index?
- based on age and height of tree/species
- helps to determine the rotation age of each site
What is forest stocking/density?
- terms used interchangeably but are slightly different
- density is the number of trees in a given area
- stocking is the adequacy of stand density to meet management objectives (ex. does stand meet maximum production of saw timber?)
- there are stocking charts for different species that shows acceptable ranges of BA for stands of different diameters
How does tree height relate to stocking/density?
- major indicator of site quality
- there is not a strong relationship between BA and site quality
How is growth and yield projected?
- regular surveys and site index assessments help project future stand conditions and wood yields
- can use different models to determine the effect of management practices on wood yield
- models can also be used to understand how changes in atmospheric CO2 affects tree growth
