UFOR 100: Forest Ecology Terms and Definitions

Vocabulary flashcards created from the UFOR 100 Forest Ecology Terms and Definitions lecture notes.

B horizon

The mineral soil horizon below the H horizon.

Canopy

The upper layer of the forest formed by the branches and leaves of mature tree crowns. The canopy can also include the organisms that live in this part of the forest ecosystem.

Co-dominant trees

Trees with crowns that form the top (highest) layer of the forest canopy. These trees receive lots of sunlight but shade each other on the sides.

Coarse woody debris

Fallen dead trees and branches on the forest floor and in rivers or wetlands.

Community

The interaction of populations of two or more species living in the same area at the same time.

Dominant trees

The tallest trees in the forest, that have crowns that are higher than the highest canopy layer.

Fermentation layer (F layer)

A layer of somewhat recognizable leaves, needles, and other organic material in various stages of decomposition. The second layer of forest soil.

Forest floor

The above-ground layer of the forest that is made up of tree roots and litter.

Gap phase dynamics

The process during which gaps open up in the forest canopy as a result of disturbance, allowing increased light through the canopy and the growth of trees and other plants in those gaps.

H horizon

An organic horizon characterized by the accumulation of decomposed organic matter.

Habitat

The natural environment of an organism. The natural environment in which an organism or population normally lives.

Humose layer (H layer)

A layer of forest soil that is formed when litter has decomposed (or humified) and in which little or no plant structures are visible. It is found below the F layer.

Hydrological cycle

The sequence of conditions through which water passes from vapor in the atmosphere through precipitation upon land or water surfaces and ultimately back into the atmosphere as a result of evaporation and transpiration (Merriam-Webster 2016).

Intermediate trees

Trees with crowns that form the mid-story canopy below the highest canopy layer of the forest.

Litter layer (L layer)

A layer of leaves, needles, twigs, and other organic material on the forest floor that has undergone very little or no decomposition. The uppermost layer of forest soil.

Litter

Dead plant material, such as leaves, needles, twigs, and bark, that has fallen on the forest floor.

Mother tree

Large, older trees that are connected to and support the growth and regeneration of younger trees through mycorrhizal networks.

Mycorrhizae

A symbiotic association between a fungus and the roots of a vascular plant.

Mycorrhizal networks

Underground hyphal networks of mycorrhizal fungi that connect the roots of plant species together. Sometimes referred to as the "wood wide web"!

Niche

The role and position of a species in its ecosystem, including all its interactions with the biotic and abiotic factors in its environment.

Nurse log

A fallen tree which supports the growth of seedlings and other plants as it decays.

Nutrient cycling

The movement and exchange of nutrients from the physical environment into living organisms and then back into the physical environment.

Pedogenesis

The process by which soils are formed.

Regeneration

The establishment and growth of young trees that renew tree cover.

Snag

A standing dead or dying tree. Older snags have often lost their tops and smaller branches.

Stand development

Changes to a stand’s appearance over time as individual trees grow, compete, and die at different rates, including the effects of disturbance events.

Stand structure

The physical form of a stand, with particular emphasis on what you might call the verticality of the woods – the extent to which both living and dead plants occupy horizontal layers from the ground to the tops of the tallest tree.

Stand

A contiguous, distinguishable group of trees with a relatively uniform age distribution, composition, structure, and soil condition (Helms 1998).

Succession

The process of change in the species structure of an ecological community over time, such that one group of species gradually replaces another.

Suppressed trees

Trees that have small crowns below the main canopy that receive no direct sunlight.

Veteran tree

A very old or ancient tree that may have high cultural or ecological value because of its age or size.

Wellness

The condition of being in good physical and mental health.

Windthrow

The uprooting and/or overthrowing of a tree caused by wind.

Wolf tree

A very large forest tree that has a wide-spreading crown and inhibits or prevents the growth of smaller trees around it (Merriam-Webster 2016).