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Categories All categories Arboriculture Terms
n
- nut1) a dry. hard. one-seeded fruit. 2) hardware with internal threads matched to the external threads oaf bolt.
- nutrienta substance that provides nourishment essential for the growth and maintenance of life; in plants. often used synonymously with essential element.
- nutrient cyclingmovement of mineral elements (sometimes called nutrients) within an ecosystem as organic matter decomposes. releasing bound nutrients back to plants.
- nutrient deficiencya condition in which the supply or availability of an essential element results in cessation of critical plant processes. resulting in visible. physical symptoms such as chlorotic leaves or necrotic margins. and which. if left untreated. will reduce tree health and may eventually lead to(...)
- nutrient limitationa condition in which the supply or availability of an essential element reduces the growth rate but does not cause plant dysfunction or premature death.
- nymphimmature form of an insect with incomplete development. resembling a smaller version of the adult without wings.
- NZ/AS4360risk management standard in Australia and New Zealand.
o
- obliquepertaining to leaf shape. lopsided. with one side larger than the other.
- obtusepertaining to leaf shape. rounded to approaching semicircular.
- ODPMOffice of the Deputy Prime Minister
- oedemasee edema.
- OHSAOccupational Health and Safety Act (Canada)
- open-face notchwedge-shaped cut (approximately 70 degrees or greater) used in felling trees or removing tree sections (contrast with conventional notch and Humboldt notch).
- opposite leafpertaining to leaf or branch arrangement. leaves or branches situated two at each node. across from each other on the stem (contrast with alternate and whorled).
- ordertaxonomic group below the class level but above the family level.
- organellesSpecialized membrane-bound part of a cell
- organic1) a substance containing carbon. 2) a substance. especially a fertilizer or pesticide. of animal or vegetable origin (contrast with inorganic).
- organic fertilizerfertilizer derived from plants or animals (contrast with inorganic fertilizer).
- organic layerlayer of organic matter at the soil surface
- organic mattermaterial derived from the growth (and death) of living organisms. The organic components of soil (see compost. green mulch. . and mulch).
- OSHAOccupational Safety and Health Administration; Occupational Safety and Health Act (U.S.)
- osmosisdiffusion of water through a semi-permeable membrane from a region of higher water potential (lower salt concentration) to a region of lower water potential (higher salt concentration).
- osmotic pressurepressure generated by the movement of water across the cell membrane caused by the difference between solute concentrations on each side.
- outriggersprojecting or extendible structures used for stabilization on aerial devices. cranes. and other vehicles that support elevated or outstretched loads.
- ovaryin trees and other plants. the part of the flower that produces the ovules and becomes the fruit at maturity.
- ovipositing (oviposition)laying of eggs by insects.
- OWdeadwood
- oxygen diffusion rate (ODR)Rate at which oxygen can be replenished if it is used by respiring plant roots or replaced by water
p
- palmmonocotyledon plant of the Palmacea family. With some exceptions. it has an unbranched trunk; its leaves are spirally arranged around the terminal bud; and the vascular bundles are scattered.
- palmatetype of compound leaf with veins or leaflets radiating in a fanlike pattern (contrast with bipinnate and pi11nate).
- PARphotosynthetic active radiation
- parasiteorganism living in or on another living organism (host) from which it derives nourishment to the detriment of the host (contrast with epiphyte and saprophyte).
- parasitoidorganism living in or on another living organism during its immature stage. killing& sterilizing. and/or consuming the host when it emerges (see parasite; contrast with epiphyte and saprophyte).
- parenchyma cellsthin-walled. living cells capable of dividing and essential in photosynthesis. radial transport. energy storage. and production of protective compounds.
- parent branchlarger branch or stem from which a smaller. lateral branch arises.
- parent materialsoil bedrock or base material from which a soil profile develops.
- particulatessmall solids suspended in air that are generated by combustion of fossil fuels. construction and demolition. industrial processes. soil tillage and erosion. and complex reactions between sunlight and gaseous pollutants. Associated with respiratory and cardiopulmonary diseases and cancer.
- patented plantplant cultivar for which exclusive rights are granted to a breeder. Only the patent holder may commercially propagate or sell the cultivar. Contrast with trademarked cultivar.
- PBZpaclobutrazol
- peaveylever with an adjustable hook and a sharp spike instead of a blunt end. Used for handling a11d rolling logs.
- peenthe act of bending. rounding. or flattening the fastening end of through-hardware for the purpose of preventing a nut from backing off." "
- penetrometera device for assessing soil compaction; can be dynamic or static.
- PERCFederal Energy Regulatory Commission
- perched water tableaccumulation of water in an upper soil layer above the actual water table. resulting when drainage in ru1 area is impeded by an impem1eable layer. such as rock or heavy clay. or when the interface between soil layers bas become stratified (i.e.. with sharp contrast in soil pore sizes) (see(...)
- percolationmovement of water through the soil (contrast with infiltration).
- perennialplants that live for more than two growing seasons (compare to annual and bien11inf).
- performance budgetingbudget format that identifies what programs will accomplish with the expenditures; includes mission statements and objectives along with performance measures. Compare with program budgeting.
- performance evaluationassessment of an employee's work quality and competence in performing the job duties. description of problems that need correcting. and identification of objectives for the future.
- performance measurementquantifiable evaluations of specific outcomes and outputs and progress toward goals.
- performance standardsdescriptions of expected work quality. behaviors. and outcomes for specific duties on which employee performance is evaluated.