Decay. The decomposition of wood substance by fungi, chemicals or heat. Two stages of decay, the "incipient" and "advanced" are ordinarily recognized, though two supplemental ones, the "intermediate:, and "final" stages are sometimes accepted. (BCFT).
Decioduous. (a) Shed naturally : applied to any plant organ or group of organs. (b) Also applied to such perennial plants as are normally leafless for some time during the year. Anton. Evergreen. Cf. Serotinous.
Defoliation. A reduction in the normal amount of foliage due to insect or fungal attack or other injury : may be partial or complete (BCFT).
Deforest, To. To remove the tree crop from a piece of land without the intention of reforesting. (the use of this word as a Syn. for dereserve is incorrect).
Degrees of Freedom (Stat.) The number of independent comparisons; the number of deviations, or items, minus the number of constants, computed from the sample for fixing the points from which the deviations are measured. (USFT).
Demarcate, To. (a) The setting out and marking the limits of a forest in terms of a notification under the forest law. (b) To mark out on the ground the limits of boundaries of a forest, compartment, crop or coupe, or plot of land for any special purposes. (BCFTmodf.).
Dendrology. The identification and systematic classification of trees. (BCFT).
Dendrometer. Any instrument used for taking measurements on trees; the term is usually restricted to instruments that measure diameter growth or to optical instruments with which diameter measurements can be taken at various points up the stem. It is not applied names, e.g. Hypsometer. (BCFTmodf.).
Denitrification (Ped.). The breaking down of nitrates and nitrites in the soil by the action of certain bacteria in the absence of oxygen resulting in the evolution of free nitrogen. Cf. Nitrification.
Density, Crop . The relative completeness of the tree stocking expressed as a decimal coefficient taking normal number of trees basal area or volume as unity . Not to be confused with canopy density. (BCFTmodf.). The terms overstocked, full or complete, and incomplete are used to describe crop density, according as it exceeds, equals or is less than 1.0. Syn. Stocking; Density of stocking; Stand density.
Desert Crust (Ped.). A hard layer, containing calcium carbonate, gypsum, or other binding material exposed at the surface in desert regions. (SSSA).
Design (Stat.). A method of arranging sample or experimental plots to minimize the effects of uncontrolled variations in fertility and other natural factors and to make it possible to estimate the magnitude of such effects in relation to those due to variations in treatment (i.e. to controlled variations). (BCFT).
Deviation. (a) (Man.). A departure from the prescription of a working plan. (b) (Stat.). The difference between any particular observation in a set of observations and the arithmetic mean of the set. (BCFTmodf.).
Diameter, Mid. The diameter of a log or a stem measured half-way along its lenght. (BCFT).
Diameter, Top. (Mens.). The diameter corresponding to the mean basal area of the biggest trees in a uniform, generally pure crop, taking into consideration the 100 biggest diameters per acre. See Age, top; Height, top.
Diameter Class. One of the intervals into which the range of stem diameters, e.g., of trees or logs, is divided for classification and use; also the trees, logs, etc. falling into such an interval (BCFT.)
Dominant. (a) (Silvic.). A tree forming part of the dominant tree class. See Tree classes, Appendix II. (b) (Ecol.). That constituent of plant community which exerts the greatest influence on its character. (c) (Genl.). A species of the upper canopy. (BCFT).
Dominated. (a) (Silvic.). Applied to a tree that has its crown somewhat below the level reached by its dominant neighbours. See Tree classes, Appendix II. (b) (Ecol.). Applied to all forms of plants occupying a subordinate position with reference to dominant plants in the same community. (BCFTmodf). See Sub-dominant.
Dormancy, Seed. A condition of mature viable seed in which germination is considerably delayed even though external conditions favour germination. (BCFT).