USDA Forest Service
 

Land and Watershed Management

 
 
   
Land and Watershed Management Program
   
Pacific Northwest Research Station
   
Olympia Forestry Sciences Laboratory
  3625 93rd Ave. SW
Olympia, WA 98512
(360) 753-7747
   
Corvallis Forestry Sciences Laboratory
  3200 SW Jefferson Way
Corvallis, OR 97331
(541) 750-7250
 
   
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Pacific Northwest Research Station logo which links to the Station's Web site.

United States Department of Agriculture Forest Service.

Genetic and Silvicultural Foundations for Management

Glossary of Silviculture Terms

FORESTRY TERMS FOR NON-FORESTERS

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Feel free to send word suggestions or other comments regarding the glossary.


APICAL DOMINANCE

When the apical bud (the terminal bud on the tips of branches) grows more quickly than the lateral buds, causing the tree to take on a tall, unrounded shape.

Photo Source: http://rst.gsfc.nasa.gov/Sect14/img020.jpg


BASAL AREA

The proportion of the total cross-sectional areas of all the stems/trunks of the plants and trees in an area. It's defined in square units per unit area and describes how stocked the stand is.

Photo Source: http://www.jemez.org/mitigation/images/MixedConifer60sqft_acre.jpg


CANOPY

The upper branches and foliage (leaves) of a tree which are exposed to sunlight and block the sunlight from reaching the understory and forest floor.

Photo Source: http://www.virginiaplaces.org/natural/graphics/closedcanopy.jpg


CANOPY VOLUME

A specific scientific proportion measuring the volume of canopy foliage (leaves) per square unit of forest floor.

Photo Source: http://espn.go.com/winnercomm/outdoors/conservation/i/P2_c_fea_BASF_trip4.jpg


COMMERCIAL THINNING

A thinning process done after the pre-commercial thinnings that is first done when the stand is about 25 years old. Trees that are cut usually have commercial value and are sold, and the trees left behind are those with the most potential for growth in the coming years and are harvested later.
(More Info)

Photo Source: http://forestresearch.ca/whats_happening/ct_workshop-oct02/CT2.jpg


CROWN BULK DENSITY

The mass of fine foliage such as leaves and small branches in a forest canopy measured as a proportion to the total canopy volume. The measurement is important regarding forest fires.

Photo Source: http://www.tlcfortrees.info/images/MatureTreeCrownDieback.jpg


ECOTONE

The border between two different types of ecosystems, e.g. deciduous forest and grassland.

Photo Source:
http://www.elkhornslough.org/research/images/ecotone.jpg


EVEN-AGED

A group of trees with insignificant height and age differences; their ages differ by less than 20% of expected life.

Image Source: http://www.woodlot.bc.ca/swp/myw/html/images/MYW-216-01.gif


INCREMENT CORE

Removing a small cylindrical cross-section of a living tree using a tree corer to find various characteristics such as age, health, and change in growth rate.

  
Photo Sources: http://fri.sfasu.edu/pages/resources/landownbriefs/img/inccore_page1.jpg and
http://www.treedictionary.com/DICT2003/hardtoget/ntb189/ntb189-figure 36.jpg


LATERAL ROOT

Roots that extend away from the taproot, parallel to the ground, from which sometimes vertical shoots sprout to the surface and produce seedlings.

Image Source: http://www.advocatesfnm.org/oldgrowth/images/lateral_root_diagram.jpg


MULTI-AGED or UNEVEN-AGED

A group of trees with significant height and age differences; their ages differ by more than 25% of expected life.

Image Source: http://www.woodlot.bc.ca/swp/myw/html/images/MYW-216-00.gif


NUTRIENT CYCLE

The recycling of nutrients such as oxygen, nitrogen, sulfur, phosphorus, and carbon through the decay of dead matter and their re-absorption into living organisms or other parts of the ecosystem such as water and air.

Image Source: http://www.bbc.co.uk/schools/gcsebitesize/img/gg04001.gif


OAK SAVANNAS

A specific type of ecosystem in which two layers of foliage exist: large, mature oak trees; and short grasses and shrubs.

Photo Source: http://www.inhf.org/graphics/snyder.jpg


OPEN-GROWN

Trees grown with little or no resource competition because the nearest trees are at least one height-radius away. These trees often produce better seed crops due to better access to sunlight.

Photo Source: http://www.capetownskies.com/1132/13_tree_field_snowd.jpg


OUT-PLANTING

Planting trees, usually seedlings, out in an exposed, natural environment after having been raised in a greenhouse or other controlled growing environment.

Photo Source: http://www2.localaccess.com/pony/keen1.jpg


OVERSTORY

Trees that are taller than most trees in that section of the forest and shade out near-by trees. This word is interchangeable with "crown canopy."

Image Source: http://www.mongabay.org/images/canopy_levels.gif


PHOTOGRAMMETRIC

Making exact measurements and making scaled maps from aerial photographs.

Photo Source: http://www.geodis.cz/www/english/photogrammetry/img/mapovani.jpg


PRE-COMMERCIAL THINNING

Reducing the numbers of trees per acre (stand density) to a level that has the highest growth rate, about 500-1500 trees per acre. This thinning process is completed with young, dense, and even-aged stands that are about 10-15 years old and is done with future commercial thinnings in mind; the lower-quality (deformed or insect-infested) trees are removed to provide more growing room for the high-quality, dominant trees.
(More Info)

Photo Source: http://www.spi-ind.com/Our_Forests/Images/Photo Library/Pre-commercial-thinning.jpg


RAIN SHADOW

The side of a mountain farthest from the region from which the prevailing winds come. This side is characterized by warm, dry climates because the air, having come from the windward side, has already been depleted of its water content.

Image Source: http://www.indiana.edu/~geol116/Week11/rainshad.jpg


REMOTE SENSING

In general terms, it is the data collection of terrestrial characteristics without any contact between the object being measured and the sensor. In forester's terms, it usually involves aircraft flying over forests gathering information about the forest's structure that is of interest.

Photo Source: http://www.learner.org/jnorth/images/graphics/mexico/ElRosario_aerial.jpg


RIPARIAN

Characterized by being on the edge or bank of a river or stream.

Photo Source: http://www.nmfs.noaa.gov/habitat/habitatprotection/images/riparian.jpg


SAPLING

A young, immature tree.

Photo Source: http://botit.botany.wisc.edu/courses/img/bot/401/Coniferophyta/Pinaceae/Pinus/P alustris/Sapling MC.jpg


SCOTCH BROOM

A large, invasive type of brush with yellow flowers which quickly and completely overruns a clearing in favor of forest succession.

Photo Source: http://home.earthlink.net/~joflee/ScotchBroom2.jpg


SILVICULTURE

The science and practice of caring for forests while maintaining human objectives in mind.
(More Info)

Image Source: http://www.ofswa.on.ca/log/images/silviculture.gif


SUCCESSION

The natural growth progress of an area after a disturbance such as logging or fire. Plant and tree species grow in cleared areas in certain ordered progressions leading up to the development of a mature and climactic forest.

Image Source: http://www.normanbirdsanctuary.org/nbu/succession/graphics/succession01.gif


TAPROOT

The largest, main root which extends straight downward from the trunk unless it encounters an obstacle in its growth. Lateral roots extend outward from its sides.

Photo Source: http://www.landscapeonline.com/research/lcn/2004/08/img/tree-care/taproot-01.jpg


TERRAIN

The topography and composition of the land, e.g. whether the area is hilly, rocky, or flat.


TREE DENSITY

A measurement of the number of trees per unit area.

Photo Source: http://www.in.gov/dnr/heritage/2000/forest.jpg


UNDERBURNING

A controlled, prescribed forest fire which only burns the shrubs and understory without damaging the mature trees.

Photo Source: http://www.nps.gov/pore/fire/slideshows/psf/images/psf15.jpg


UNDERSTORY

A layer of trees that are significantly below the forest canopy but have cleared the ground level shrubs.

Photo Source: http://www.voruidoso.com/Images/Forestry Images/Photo Gallery/Understory Gambel oak.JPG


WINDWARD SIDE

The side of a mountain closest to the region from which the prevailing winds come. As the air rises over the mountain, the water condenses to cause precipitation before crossing the summit to the rain shadow. This area is characterized by a lush landscape with regular precipitation.

Image Source: http://rst.gsfc.nasa.gov/Sect14/img020.jpg


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USDA Forest Service - GenSilv Team
Last Modified: Monday, 16 December 2013 at 14:18:50 CST


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