2.18.97
The Virtual WeedPatch
Biology & Ecology
habitnotes.html
Weedy Habitats Notes
Terminology:
Habitat: the locality, site, and particular type of local environment occupied
by an organism (for us, a weed)
Microhabitat: a very localized habitat (Example: on the size scale of an
individual seed in the soil seed bank)
Niche: the ecological role of a species in a community; conceptualized as
the multidimensional space, of which the coordinates are the various parameters
representing the conditon of existence of the species, to which it is restricted
by the presence of competitor species; sometimes used loosely as an equivalent
of microhabitat in the sense of the physical space occupied by a species.
Factors in the environment that affect weedy growth and success: Factors
that define the character of a habitat, related concepts within each factor.
Topography factors:
-Slope: a measure of inclination of the land surface with respect to the
horizontal; gradient
-Aspect: the direction the land surface faces (e.g. north) if not horizontal;
used with slope
-Elevation: height above sea level
Environmental factors:
-Light: sunlight and its heat; light quantity [day length, night length];
light quality [wavelengths stimulating flowering, growth]
-Moisture: precipitation [rainfall, snow, hail]; surface water [streams,
lakes]; ground water; seasonal rainfall
-Drainage: distance to the water table; flooding & flood plain proximity;
water holding capacity of the soil; impermeable soil or subsoil layers
-Temperature: heat [air, and at soil depths]; heat units; seasonal heat
unit accumulation
Land use factors:
-Type and level of management of the habitat by humans: crop field, a residential
lawn, a waste field near a factory, a highway roadside, etc.
