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Habitat
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The local environment in which a plant or animal lives; includes the food, water, and shelter necessary for its survival.
Hardening Off
- Preparing seedlings or rooted cuttings for
planting by gradually reducing water, nutrients, or light intensity
and thus inducing changes in shoots that make them more resistant
to desiccation, cold, etc.
Hardwood
-
A term used to describe broadleaf, usually deciduous, trees such as oaks, maples, ashes, elrms, etc.
Harvest
-
The removal of timber for use. Includes felling, extraction, and sometimes initial processing.
Heartwood
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This wood occupies the central core of many trees and consists of darker coloured wood that is impregnated with substances that make it resistant to fungus and decay, and is, as well, more dense than sapwood.
Herbicide
-
Chemicals which kill herbaceous plants.
Heritability
- That portion of the character variance due
to hereditary factors as distinct from factors of environment.
Heritability is described in one of two ways, depending on the
type of investigation. In progeny tests (based on sexually propagated
material) it is described as narrow sense and is the ratio
of the additive genetic variance to the total (i.e., genetic +
environmental = phenotypic) variance of a character; in clonal
tests (based on vegetatively propagated material) it is described
as broad sense and is the ratio of the total genetic variance
to the total (i.e., phenotypic) variance of a character.
High Forest
- Crops and stands of trees, generally of seedling
origin, that normally develop a high closed canopy. A term originally
used to differentiate the natural, essentially seedling forest
of long rotation from the artificial, coppice forest of shorter
rotation.
High Forest Systems
- Silvicultural systems in which the
crops are normally of seedling origin, natural and/or artificial,
and the rotation is, traditionally at least, long.
High Grading
- A partial harvest removing only the most valuable
species or trees of desirable size and quality without regard
for the condition of the residual stand.
High Thinning
- see Thinning: crown thinning
Humus
- 1. A general term for the more or less decomposed
(plant and animal) residues in the soil, litter therefore being
excluded. Humus layer is a general term for the surface
layers composed of or dominated by organic material, whether unincorporated
or incorporated with mineral soil, or at some intermediate stage.
- 2. More specifically, the more or less stable fraction from the
decomposed soil organic material, generally amorphous, colloidal,
and dark colored.
Hybrid
- The offspring of genetically different parents (usually
refers to crosses between two species).
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