Habit. The shape, general appearance and mode of growth common to the individuals of a species or other systematic group.

Habitat. (a) ( Ecol.) The sum of effective environmental conditions under which an organism lives. See Environment. (b) Often used for the natural range of distribution of a species ( Deprec.). (c) The kind of place in which a plant or animal lives, such as forest habitat. grassland habitat etc.

Halophyte. A plant growing on saline soil.

Halosere. ( Ecol.). A sere which has its commencement in salt water.

Hammer-Mark, To, To mark timber, standing or felled, with a marking hammer, See Mark timber, to .

Haploid ( Genet.). Having one chromosome set only; the individual so constituted. This is the characteristic condition of sexual cells. Cf. Diploid ; Meiosis. ( BCFT).

Hardening Off. (a) Preparing seedlings in a nursery for planting out by gradually reducing watering, shade, and/or shelter resulting in a hardening of the plant.(b) The natural process whereby plants become adapted to drought, cold or heat. ( BCFT modif).

Hardwoods. A conventional term, used irrespective of physical hardness or softness, for broad-leaved trees and their timber which are known softwoods. in countries where conifers are of little commercial importance, however, the terms are commonly used in their literal sense. In India the lighter hardwoods are often called 'light' or 'soft' hardwoods. ( BCFT modif.).

Hazard ( Protec). (a) A measure of that part of the fire danger which is dependent on the materials available for burning, and its relative amount, class character, moisture content and condition. (b) inflammable material constituting a threat of special suppression difficulty or of likelihood of ignition because of location .

Note :- In forest protection , the following terms have each the limited meaning given against it:

HAZARD : concerns inflammable material only.

INFLAMMABILITY : is the susceptibility of the material to ignition.

RISK : refers only to the agencies that cause fires.

DANGER : is the sum of them all, plus damage and other factors.

As used by the general public, no distinction is consistently made between hazard and risk ( BCFT modif.).

Hazard Reduction ( Protec.). Any treatment of inflammable material, other than accidental burning, that result in diminishing the chances of fire starting or spreading in them. ( BCFT modif.).

Heart. The central core of a tree or log; usually the pith with a small portion surrounding it. Syn pith.

Heartwood. The inner layers of wood, which in the growing tree, have ceased to contain living cells. It is generally darker in colour than sapwood though not always clearly differentiated from it. Syn. Duramen; True Wood.

Hectare. Area measure in the Metric system, equal to 10,000 sq. meters or 2.471 acres.

Heel in, To. To store young plants prior to planting by placing them in a trench and covering the roots or rooting portions with soil ( BCFT).

Height (Tree). The straight line distance between ground level and the extreme top of a tree; usually measured on slopes on the uphill side of the tree. Syn. Total height.( BCFT modif.).

Height Dominant. See Height, top.

Height, Crop ( Mens.). A term used in sample plot work and yield table in India, and refers to the average height of a regular crop as determined by Lorry's formula.

Height, Mean. The height corresponding to the mean diameter of a group of trees or the crop diameter of a stand. Cf. Height, crop.

Height, Merchantable. The height up a tree to which it is saleable. ( BDFT). Syn. Commercial bole.

Height, Stump. The height of the top of a stump above ground.( BCFT).

Height, Timber. (a) ( Gen.). Sometimes loosely used for merchantable height.(b) ( Mens.). The height of the tree to a point where its girth or diameter falls to a specified minimum or the point where the main stem branches out into the crown, whichever is lower. It may be reckoned from ground level or stump height. ( BCFT).

Height, Top ( Mens.). (a) in general terms, it is the average height of the dominant trees in a stand. (b) As used in sample plot work and yield tables in India it refers to the height corresponding to the mean diameter (calculated from basal area ) of the 100 biggest diameters per acre as read from the height/diameter curve.

Height Class. One of the intervals into which the range of tree heights is divided for classification and use; also the trees falling into such an interval. ( BCFT).

Height Growth. Increment in height.

Heliotropism. The response in growth or position of plant organs to the direction of light; positive when growth is towards the light, negative when away from it. ( BCFT). Syn. Phototropism. Cf. Geotropism.

Halophyte ( Ecol.). A class of Raunkiaer's life forms comprising plants with perennating buds lying in muddy non-saline soils; a marsh plant.

Hemicrytophyte ( Ecol.). A class of Raunkiaer's life forms comprising plants with prennating buds at soil level.

Herbage. A growth of herbs, that is, plants with no persistent stem above ground. ( BCFT.).

Heterogamy. (a) (Genet.). The condition of having gametes differing in size and/or constitution. (b) (Bot.). That of having flowers of two or more sexual types in the same inflorescence (c) ( Entom.). That of a parthenogenetic generation which alternates with a truly sexual one. ( BCFT.).

Heterosis ( Genet.). The manifestation in a hybrid of a degree of vigour superior to that exhibited by either of its parents. Syn. Hybrid vigour. ( BCFT).

Heterotic. Characterized by Heterosis. ( BCFT.).

Heterotrophic Plants. Those which cannot live without organic food, obtained more or less ready-made from bodies or other organisms. Cf. Autotrophic. ( BCFT modif.).

Heterozygous ( Genet.). An individual is said to be heterozygous in respect of a particular character when the pair of genes carrying that character are dissimilar. Anton. Homozygous ( BCFT).

Hibernation. Passing the winter or cold season in an inactive state Cf. Aestivation. ( BCFT).

Histogram ( Stat.). A diagram representing the frequencies of the values of a variate between specified limits by means of rectangles of equal width whose areas are proportional to the frequencies. ( BCFT modif.).

Holard. The total water content of the soil.

Holard=Echard + Chresard.

Hole, Bore. (a) A hole formed in a cell wall by the dissolving action of an advancing hypha of a wood inhabiting fungus. Syn. Hyphal hole (b) A hole in plant tissues, e.g. bark or a wood surface, made by a boring organism. ( BCFT). Syn Pin-holes; Shot-holes; Worm-holes.

Hole, Emergence. A hole made through the outer bark, wood surface, or fruit for the emergence of insects. Syn. Exit. hole; flight hole ( BCFT).

Hole, Hyphal. See Hole, bore (a)

Hole, Ventilation. A hole made by adult bark beetles from their egg galleries to the surface for the purpose of ventilating these galleries, disposing of excess boring dust and for turning round. Syn. Ventilation tunnel ( BCFT).

Homogamy. (a) ( Genet). Inbreeding due to isolation. Cf. Heterogamy. (b) (Bot). (1) the condition of having flowers of the same sex, viz. male, female, and hermaphrodite. Cf. Heterogamy (b).(2) Having stamens and pistils maturing in a flower at the same time. ( BCFT).

Homozygous ( Genet.). An individual is said to be homozygous in respect of a particular character when the pair of genes carrying that character are similar. Anton Heterozygous. ( BCFT)

Host. An organism on , or within which another organism feeds and develops. ( BCFT)

Host, Alternate. A second host species essential for the completion of the life history of a parasitic organism. ( BCFT).

Host, Alternative. A second host species which may form the food of a parasitic organism, but is not essential for the completion of its life history. ( BCFT).

Humidity, Absolute. The amount of water vapor per unit volume of space. ( BCFT).

Humidity, Relative. The ratio, generally expressed as a percentage of the amount of water vapor preset in the air to the amount required for saturation at the same temperature. ( BCFT).

Humification ( Ped.). the decomposition of plant and animal matter into amorphous, relatively insoluble organic compounds, usually dark in colour. ( BCFT).

Humus ( Ped). (a) The more or less decomposed organic matter of the soil which may form a separate layer or be intimately mixed with the mineral particles (intimate humus). The two forms constitute the two types of humus known as Mor and Mull respectively. (b) (A more restricted use)- The dark coloured amorphous colloidal organic matter of the soil. ( BCFT modif.). The following types of humus are distinguished :-

acid or sour humus, resulting from decomposition under an aerobic conditions.

raw humus or litter, the portion of the forest floor which is not in an advanced state of decomposition.

leaf mould, the decomposition products of leaves other than those of conifers, having the appearance of fine earth.

Husk, To. The strip off the external integument or covering of fruits or seeds.

Hybrid ( Genet.). The product of a cross between individuals of unlike genetic constitution; denoted by X between the scientific names. ( BCFT).

Hydrarch Succession ( Ecol.). Succession beginning in water or very wet land as in ponds, lakes, marshes, etc. See Hydrosere. Cf. Xerarch succession.

Hydric ( Ecol.). Applied to a habitat that is wet. Cf. Xeric; Mesic.

Hydromorphic Soils ( Ped.). Soils developed in the presence of excess water.(SSSA).

Hydrophilous ( Ecol.). Inhabiting wet land or water. ( BCFT).

Hydrophyte ( Ecol.). (a) A plant which grows wholly or partly immersed in water. ( BCFT). (b) A class of Raunkiaer's life formscomprising plants with perennating buds lying in water.

Hydrosere. The different stages in hydrarch succession. Cf. Lithosere: Xerosere.

Hygrometer. An instrument or apparatus for measuring the relative humidity of the atmosphere. ( BCFT).

Hygrophilous. Inhabiting moist sites. ( BCFT).

Hygroscopicity. The power to absorb moisture from the atmosphere and retain it.

Hygrothermograph. An instrument that records automatically and continuously both temperature and relative humidity on a single chart. ( BCFT).

Hylium ( Ecol.). A term denoting climax woodland formations or associations, e.g., Quercus-pinus hylium. The seral equivalent is hylis.

Hyperparasite. An organism parasitic upon another parasite. ( BCFT).

Hypha. One of the thread-like elements which form the mycelium of a fungus. ( BCFT).

Hypsometer. An instrument for determining the height of standing trees from observations taken at some distance from the tree. ( BCFT).