Rezatec

Allometric equation: Mathematical term used to provide biomass estimates from tree measurements. These equations usually require information on diameter at breast height (DBH) and height.

Basal area: A key mensuration metric -usually measured in m² - which defines the cross-sectional area of a tree at its ‘breast height’ (4.5ft/1.37m). Basal area can be calculated using the diameter at breast height (DBH) but is more commonly estimated using a relascope. The basal area is used for quick, lower precision mensuration alongside more rigorous plot sampling. Basal area is also used alongside assessing the intensity of thinning in an area and to monitor stand stocking.

Brushing: A North American term for the removal of brush (i.e., shrubs, herbs) and weed species which compete with seedlings for sunlight, water, and soil nutrients. Brushing is also referred to as: 

• cleaning if connected to regeneration trees.
• weeding if connected to herbaceous vegetation.

Clear-felling/ clear-cutting: Technique referring to the harvesting of all trees from a block/stand in a single cut.

Continuous Cover Forestry (CCF): An alternative technique to clear-felling/clearcut silvicultural systems where single tree/groups are selected for felling to ensure continual tree cover on a site. Around 30% of European forests are managed using this approach. 

Diameter at Breast Height (DBH): Measurement used for stem diameter. This is designed to be easy to measure and avoid bias from buttressing at the base of the tree. DBH is used alongside tree height and allometric equations to estimate tree volume.

Disturbance: A temporary change in environmental conditions that causes pronounced change within an ecosystem. In a forestry context, these activities range from: 

• Harvesting 
• Wind or storm damage 
• Illegal logging 
• Fire
• Insect infestation

Field data: Information concerning forest plots or stands within or in a surrounding location. 

Harvester: Forestry machinery commonly used to carry out harvesting operations. The machine fells and processes trees directly into product lengths. The harvester can be calibrated to measure volume of timber processed as it is cut. 

Harvesting: The cutting and extraction of timber to roadside, usually during thinning or clear-felling. 

Inventory: The systematic collection of data within a forested location or given area. Gathered data usually includes species, diameter at breast height (DBH), height, site quality, age, and defects. 

Layout: Marking of trees in an area for harvest. 

Lumber: American term used for harvested wood or wood products; synonym for timber. 

Mean Annual Increment (MAI): Estimate given for the average volume increment per acre/hectare per year, i.e., volume per hectare divided by number of growing seasons. Management planning and silvicultural interventions seek to maximise MAI. 

Mensuration: A technique used to deal with the determination of dimensions (e.g., diameter, height, volume etc.), form and age of single trees, stands or whole woods. 

Merchantable Timber: Describes timber which is saleable for commercial products. Examples of non-merchantable timber could include dead stems, or on live trees, growing timber where the stem is below a threshold diameter.

Non-contiguous: Term used to describe pockets of land dispersed across areas of forest.

Plot:  Broad term to describe a sample area of a stand where measurements are carried out. These can be described in two forms: 

• Permanent sample plots which are carefully measured and marked out for repeat measurement (either for yield modelling, long term monitoring or research).
• Temporary sample plots which are used for tariffing/cruising and can be used to update inventory or to estimate sale volume.   These can be square, circular or diamond plots and are usually scaled to be x hundredths of an acre or hectare. Sampling intensity varies with crop uniformity and desired accuracy. Location will be recorded but they may not be revisited.

Prism: Glass device used to estimate basal area or variable plot sampling. To interpret this data, we need the Basal Area Factor (BAF).

Reconnaissance: Generalised survey where lumber is identified for removal/salvage following a disturbance event. 

Reforestation: Term to describe natural or artificial restocking (i.e., planting or seeding) of an area with forest trees. This can also be referred to as ‘forest regeneration’ or simply replanting/restocking.

Respacing/pre-commercial thinning: The removal of a proportion of naturally regenerated trees to prevent the stand from becoming over-stocked. Optimum stocking ensures enough competition to stimulate growth without suppressing it altogether.

Salvage: The practice of logging trees in forest areas which have been damaged by wildfire, flood, severe wind, disease, insect infestation etc. 

Sample Plotting: Process of measuring forest stands manually on the ground to determine stand characteristics e.g., average tree sizes, volume, quality. This can also be referred to as ‘timber cruising’ in North America.

Silviculture: Management of trees and forests for timber production. This often includes targeted interventions (e.g., by spraying, brushing/weeding, and thinning etc.) to ensure young trees grow with desired vigour and form.

Site Index: Metric used to describe the productive potential of a site, given as the top height at a reference age.

Spraying: The targeted application of herbicides or insecticides to minimise competition and/or damage to crop trees.  

Softwood/Hardwood: Distinction between the timber of conifers and broadleaves. 

• Hardwood comes from broadleaved trees. Broadleaves tend to be slower growing, meaning the wood is usually denser.  
• Softwood comes from (typically faster growing) coniferous trees. 

Stand: Contiguous community of trees sufficiently uniform in composition to distinguish it from adjacent communities. 

Stumpage pricing/standing sale: The sale of timber on the basis that the purchaser will arrange and finance the felling operation and subsequent logistics. 

Thinning: A silvicultural treatment that removes a proportion of trees from a stand. Often these will be stems which are large enough to be sold as products such as poles or fence posts to make the operation self-financing (commercial thin). 

Top Height: The average height of dominant trees, sampled by measuring the heights of the highest-DBH trees in several sample plots. Strong relationships exist between stand top height and annual increment making it a powerful metric for site productivity and estimation of increment where robust yield models exist.

Weeding:  The removal of competing vegetation by either mechanical or chemical means.

Wood-basket/bounding extent:  The full geographic extent to which timber can be obtained for a mill. 

Yield models: Used to predict future timber volumes by forward projecting tree growth. This informs long-term strategic planning and underpins sustainable forest management.