Damping off. The killing of young seedling by certain fungi that cause decay of the stem, or roots. (BCFT)

d.b.h. Abbr. for Diameter at breast height.

Decalcification (Ped.). Removal of calcium carbonate ions from the soil by leaching. (SSSA).

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.

Deflation (Ped.). Removal of fine soil particles from soil by wind erosion. (SSSA).

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. (BCFT modf.).

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. (BCFT modf.).

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, Canopy. The relative completeness of canopy usually expressed as a decimal coefficient, taking closed canopy as unity (BCFT modf). The following classification of canopy density is in vogue :-

Closed when the density is 1.0

Dense when the density is between 0.75 and 1.0.

Thin when the density is between 0.5 and 0.7;and

Open when the density is under 0.5 Cf. Density crop

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. (BCFT modf.). 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.

Density, Stand. Syn. Crop density.

Density of Stocking. See Density, Corp.

Denude, To. To lay bare, usually with respect to the soil, by the removal of its vegetable cover or organic layers.

Deposit (Noun) (Ped.).Material left in new position by some natural transporting agent such as water; wind, ice, or gravity. (SSSA).

Depot. A site on which forest produce is collected.

Dereserve, To. To declare by law that an area of forest reserve shall cease to be a reserved forest. Syn. Disreserve (Deprec.). Cf. Disafforest; Deforest.

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).

Development of Vegetation (Ecol.). Succession resulting from autogenic factors. Syn. Autogenic Succession.

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. (BCFT modf.).

Deviation, Mean (Stat.).The mean value of the deviations from the mean, taken irrespective of sign. (BCFT). Syn. Average deviation. Cf. Deviation, standard.

Deviation, Standard (S.D.) (Stat.). A measure of the dispersion about the mean of the population. (BCFT). . Cf. Deviation, mean.

Dew Point. The temperature at which water vapour present in the atmosphere is sufficient to saturate it. (BCFT).

Diameter, Breast Height. (Abbr. d.b.h.). the diameter of a stem measured at breast height; it is generally taken over bark for trees. (Abbr. d.b.h. o.b.). (BCFT modf.).

Diameter, Crop. (Mens.). The diameter corresponding to the mean basal area of a uniform, generally pure crop. Cf. Diameter, mean.

Diameter, Exploitable. The minimum diameter at breast height at which trees are considered suitable for exploitation. (BCFT). See Girth, exploitable. Cf. Size, exploitable.

Diameter, Mean. The diameter corresponding to the mean basal area of a group of trees or a stand; sometimes used for the arithmetic mean of the summated diameters. (Deprec.). (BCFT). Cf. Diameter, crop.

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.)

Diameter Quotient. The ratio of the diameter of a stem at any given height to its breast height diameter. Cf. Form quotient. (BCFT modf.).

Dibble, To. To sow seeds in shallow holes made with a suitable instrument.

Dieback. (a) The progressive dying, usually backwards from the tip, of any portion of a plant. (BCFT). (b) The death of the shoot, the root remaining alive.

Diffuse-Porus Woods. Hardwood in which the pores (vessels) are scattered of diffused throughout the growth ring without any abrupt diminution in size from the spring wood to the summer wood. Cf. Ring-Porus woods. (BCFT modf.).

Dioecious. Applied to flowering plants having unisexual (male or female) flowers on separate individuals. Cf. Monoecious.

Diploid (Genet.). Having the usual two chromosome sets ; individual so constituted, the normal condition for vegetative tissues of higher plants. Cf. Haploid; Meiosis; Polyploid. (BCFT).

Disafforest, To (Deprec.). Often used as a synonym for dereserve; it also covers corresponding action in the case of Protected Forests.

Disclimax (Ecol.). Abbr. Disturbance climax . Any proclimax that originates from and is maintained due to disturbance by man or domestic animals. See Climax, Biotic.

Disforest, To. Syn. (Deprec.). Deforest; Dereserve.

Dispersion (Stat.). The range of variation of the values in a set of observations of a character common to the individuals of a population. (BCFT).

d.o.b. Abbr. for diameter over or outside bark.

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).

Dominant Character (Genet.). One that is fully developed whether the gene producing it is present in one or both members of the chromosome pair, i.e., whether the individual is heterozygous or homozygous. Anton. Recessive character. (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. (BCFT modf). See Sub-dominant.

Dormancy, Seed. A condition of mature viable seed in which germination is considerably delayed even though external conditions favour germination. (BCFT).

Dormant (or Latent) Bud. A bud that remains inactive for an indefinite period until stimulated into growth. (BCFT).

Drag-hole. A hole cut at one end of a log to facilitate the attachment of gear for dragging .

Drainage Area. See Catchment area.

Drift (Geol.). Unconsolidated geological material that has been moved from the site of weathering (BCFT).

Drift-wood. Timber that is a drift, beached, stranded or sunk (in a river, lake or sea ). (See Sec. 45, Indian Forest Act). Cf. Waif.

Drill. (a) A line impressed on a seedbed for receiving seed.

(b) Any implement used for making such impressed lines.

d.u.b. Abbr. for Diameter under bark.

Duff. Syn. for Mor.

Dune. Moving hillock formed by shifting sand.

Durability. Of wood, the resistance offered by it against disease, decay and insect attack.

Duramen. See Heartwood.

Dysgenic (Genet.). tending towards racial deterioration, in particular towards loss of vigour and productiveness. Anton. Eugenic. (BCFT).