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- Humboldt notchfelling notch that is horizontal on the top and angled on the bottom. Also called Humboldt scarf or reverse scarf (contrast with conventional notch and open-face notch).
- humusdark-colored. stable form of organic matter that remains after most of plant or animal residues have decomposed.
- HVhigh voltage
- hybridplant resulting from a cross between two or more other plants that are more or less alike.
- hydrocarbonorganic chemical compound containing hydrogen and carbon atoms. Hydrocarbons from fossil fuels are linked to pollution and global warming.
- hydrogelscrystalline polymers which absorb water and. if needed. can be added to the soil to increase its water holding capacity.
- hydrophilicthe physical or chemical property of a molecule or substance that is attracted to water (and may be dissolved in water).
- hydrophobicthe physical or chemical property of a molecule or substance that repels water.
- hydrozoninggrouping plants in a landscape according to their water requirements.
- hygroscopicretained water that is held too tightly in soil for uptake by plants.
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- I running endend of a rope not in use (contrast with I standing part and working end).
- i-Treesuite of software products and management tools including STRATUM. UFORE and MCTI; allows the user to inventory the urban forest and analyze its costs. benefits. and management needs.
- IAAindoleacetic acid
- IBAindolebutyric acid
- IBDUisobutylidene diurea
- ICFInstitute of Chartered Foresters
- identification keyguide used to help identify plants and other organisms.
- imminent threatin Integrated Vegetation Management (IVM). a vegetation condition that could cause damage or interruption of service to overhead energized facilities or pipelines at any moment.
- immobileIncapable of being moved in plant tissue or soil
- impervioussurface that does not allow for infiltration and/or penetration of liquids.
- implant1) device. capsule. or pellet inserted into the tree's xylem system to treat or prevent diseases. disorders. or pest problems. Requires a relatively large diameter and deep hole in the trunk (contrast with macroinfusion. macroinjection. and microinjection). 2) a micro-chip device implanted(...)
- import soilsoil brought into a site from another location.
- in-archForm of repair grafting used when roots have been damaged or injured
- incompatible vegetationvegetation that is undesirable. unsafe. or interferes with the intended use of the site.
- increment borerdevice used to take core samples from trees to determine age or detect problems. such as decay (see micro drill resistance testing). indeterminate growth continued growth due to sustained activity of the apical and lateral meristems (contrast with determinate growth).
- indicator plantplant species that exhibit early. reversible symptoms of drought stress and are specifically used in hydrozones to signal a need for watering.
- indigenous plantspecies that originate and occur naturally at a site.
- indirect contactexposure to electrical current by touching any electrical conductor that is in contact with an energized conductor.
- infectiouscapable of being spread to plants from other plants or organisms.
- infestationthe presence of a pest population on a host plant or group of plants.
- infiltrationI) downward entry of water into the soil (contrast with percolation). 2) entry of fine particles into drainage or aeration systems; can lead to system clogging and failure. 3) downward entry of materials from one soil or fill layer to another. as when a gravel road surface mixes with(...)
- infiltration ratespeed at which water penetrates the soil.
- inflorescencecluster of flowers. in-ground fabric-bag grown trees and shrubs field grown in fabric bags. commonly called grow bags (contrast with balled and burlapped. bare root. container grown. and containerized).
- infrastructurefacilities and systems. such as sewers. roads. utilities. serving a community.
- injectioninjection of a liquid substance into a plant or soil.
- inoculantsin soil science. microorganisms (e.g.. mycorrhizal fungi) that are introduced into the soil in order to improve growth or plant health.
- inoculumpart of a pathogen that can enter the host and can cause disease.
- inorganiccompound or substance not containing carbon. Not containing organic material (contrast with organic).
- inorganic fertilizermineral fertilizer. not coming from plant or animal sources (contrast with organic fertilizer).
- insect growth regulatorssubstances. man-made or naturally occurring in insects. that affect growth and development of insects.
- insecticidal soapssoap-based pesticides approved for application to plants to kill insects and certain mites by disrupting the cell membranes or the insect's respiratory tracheas.
- insecticidessubstances toxic to insects.
- instarstage of growth between molts in the development of insect larvae.
- Integrated Pest Management (IPM)method of managing pests that combines cultural. biological. and chemical control tactics into a single management strategy.
- internodalbetween the nodes on a stem.
- internoderegion of the stem between two successive nodes (contrast with node).
- interveinalpace b tween the veins on a plant leaf
- interveinal chlorosisyellowing of interveinal tissue.
- interveinal tissueleaf tissue between the veins or vascular bundles. J
- introduced speciesorganisms not native to a region (contrast with exotic species. native species. and naturalized species).