Botantical / Plant Terms

Botanical / Plant Terms

  • Barrens:

    • Definition: Woodland or shrubland communities characterized by suppressed tree establishment or growth due to environmental conditions and/or disturbance regimes.

    • Occurrence: Often found on thin or excessively drained soils.

  • Bog:

    • Definition: A nutrient-poor, acidic peatland receiving water primarily from direct rainfall, with minimal input from groundwater/runoff.

    • Vegetation: Primarily consists of peat mosses (Sphagnum spp.) and ericaceous shrubs.

  • Canopy:

    • Definition: The uppermost layer of vegetation in a community formed by the branches and leaves of plants.

    • Coverage: A canopy is considered closed (100% cover) when the lower strata are fully shaded during the growing season.

  • Characteristic species:

    • Definition: A species that is strongly associated with a particular community type, serving as either a dominant or very common component.

  • Co-dominant:

    • Definition: A species that exhibits relatively high abundance or percent cover, often alongside other species providing roughly equal cover and abundance in a community or stratum.

  • Community:

    • Definition: An assemblage of plants and/or animal populations interacting and sharing a common environment.

  • Conifer:

    • Definition: A large group of cone-bearing trees and shrubs, mainly evergreens such as pine, spruce, and fir.

    • Note: Some conifers, like tamarack and bald cypress, lose their leaves yearly and are not considered ‘evergreen.’

  • Disturbance:

    • Definition: A temporary change in average environmental conditions causing significant changes in an ecosystem.

    • Types: Can be natural (e.g., blow-down) or human-induced (e.g., logging, invasive species introduction).

  • Dominant:

    • Definition: A species with the greatest abundance, percent cover, or ecological influence within a community or stratum.

  • Edaphic:

    • Definition: Relating to soil, particularly as it affects living organisms.

    • Characteristics: Includes factors such as water content, acidity, aeration, and nutrient availability.

  • Ericaceous:

    • Definition: Pertaining to members of the heath family (Ericaceae) that thrive in acidic soils.

  • Exotic:

    • Definition: Species not native to Pennsylvania or the area where they occur.

  • Forb:

    • Definition: A broad-leaved, herbaceous plant that is not grass-like; may include ferns and fern allies.

  • Forest:

    • Definition: A type of community dominated by trees over five meters in height and having at least 60% canopy closure with interlocking crowns.

    • Subtypes: May be classified as terrestrial or palustrine.

  • Graminoid:

    • Definition: Grass-like herbaceous plants characterized by narrow leaves, including grasses (Poaceae), sedges (Cyperaceae), rushes (Juncaceae), and others.

  • Grass:

    • Definition: A member of the grass family (Poaceae).

  • Ground layer / Ground flora:

    • Definition: Refers to the herbs, shrubs, and woody vines located beneath trees in a forest; or the lowest layer of vegetation in an open-canopy community.

  • Hardwood:

    • Definition: Trees that are broad-leafed and deciduous present in the region.

  • Heath:

    • Definition: A member of the family Ericaceae that thrives in acidic soils.

  • Herb / Herbaceous:

    • Definition: Plants that lack a persistent woody stem above ground, distinguishing them from trees and shrubs.

  • Herbaceous layer:

    • Definition: The layer of vegetation where herbs are common, typically equivalent to the ground flora.

  • Herbaceous perennial:

    • Definition: A perennial plant that dies back to its rootstock each Fall and regenerates in Spring.

  • Hydrophyte / Hydrophytic:

    • Definition: Plants adapted to grow in water or on substrates deficient in oxygen due to excessive water content; they thrive in hydric soils.

  • Invasive species:

    • Definition: A non-native species introduced to a specific area that likely causes economic or environmental harm or poses risks to human health.

  • Native:

    • Definition: Species that existed in Pennsylvania before European settlement and were not introduced through human activities; considered indigenous.

  • Old Growth:

    • Definition: Near-climax forest stands that have experienced few or no intrusions by humans.

  • Palustrine:

    • Definition: Pertaining to freshwater wetlands.

  • Perennial:

    • Definition: A plant that lives longer than two years.

  • Shrub:

    • Definition: A perennial, woody plant, less than five meters in height, exhibiting a multi-stem growth form.

  • Spring ephemeral:

    • Definition: Refers to a type of forest wildflower that blooms briefly in the Spring before the canopy leaves fully develop.

  • Structure:

    • Definition: The spatial arrangement of vegetation layers within a community.

  • Successional:

    • Definition: Communities characterized by changing composition over time.

  • Swamp:

    • Definition: A wooded wetland that is intermittently or permanently flooded.

  • Terrestrial:

    • Definition: Referring to uplands, supporting vegetation that is not mainly hydrophytic.

  • Tree:

    • Definition: A woody perennial plant, typically with one main stem, defined by a mature height of at least five meters and a notable crown.

  • Understory:

    • Definition: The lower layers of vegetation within a community; all vegetation beneath the canopy and sub-canopy in a forest.

  • Vernal:

    • Definition: Pertaining to Spring; vernal pools are temporary shallow woodland ponds that support herptiles (e.g., salamanders, frogs) during their aquatic life stage.

  • Wetlands:

    • Definition: Areas that are transitional between aquatic and terrestrial habitats, characterized by a prevalence of hydrophytes and conditions typically moist enough during the growing season to produce anaerobic soil conditions and influence plant growth.

  • Woodland:

    • Definition: A community featuring a sparse tree canopy (10%-60% cover), generally with an herbaceous and/or shrub layer; indicative of environments where tree establishment or growth is constrained by edaphic conditions or disturbance regimes.

  • Woody:

    • Definition: Plants characterized by lignified stem tissue, which includes trees, shrubs, and woody vines.

Geologic and Soils Terms

  • Acidic:

    • Definition: Soil or water with a pH lower than 7; soils with a pH below 5.5 are classified as strongly acidic.

  • A-horizon:

    • Definition: The top layer of soil horizons, also known as 'topsoil', which contains decomposed organic materials known as humus.

  • Alluvium:

    • Definition: Unconsolidated material (gravel, sand, silt, clay, and mixtures) deposited by flowing water.

  • Anticline:

    • Definition: A geological fold in rock strata that is raised up into an arch shape as a result of folding.

  • Basic:

    • Definition: Soil or water with a pH higher than 7.

  • Bedrock:

    • Definition: The solid rock layer that is either exposed at the surface or lies beneath the soil or unconsolidated material.

  • B-horizon:

    • Definition: The layer of subsoil located beneath the A-horizon.

  • Calcareous:

    • Definition: Refers to soil, groundwater, or surface water with elevated calcium concentrations, typically derived from limestone or calcium-rich glacial deposits; results in a higher pH compared to acidic soils.

  • Carbonate rock:

    • Definition: Sedimentary rock primarily composed of carbonate minerals such as limestone or dolomite.

  • Dolostone / Dolomite:

    • Definition: A type of sedimentary carbonate rock composed mainly of calcium magnesium carbonate.

  • Duff / Ground litter:

    • Definition: Fresh or partially decomposed organic debris (leaves, twigs); can refer to the O-horizon in a soil profile.

  • Chroma:

    • Definition: The perceived intensity of color; a chroma of 2 or lower on the Munsell scale indicates dull colors, usually linked with hydric (wetland) soils undergoing anaerobic processes.

  • Colluvium:

    • Definition: Soil and rock fragments at the base of slopes that have predominantly moved through gravitational action.

  • Floodplain / Lowland:

    • Definition: Flat to nearly flat areas adjacent to water bodies that are prone to flooding.

  • Gleyed soil:

    • Definition: Hydric soil exhibiting characteristic gray mottling, formed under anaerobic conditions.

  • Homocline ridge:

    • Definition: A ridge formed from underlying strata tilted uniformly in a particular direction.

  • Hydric:

    • Definition: Wet soils sufficient to produce anaerobic conditions in the root zone.

  • Interbedded:

    • Definition: Alternating layers of differing rock types, such as shale and sandstone.

  • Limestone:

    • Definition: A type of sedimentary rock composed predominantly of calcium carbonate.

  • Mesic:

    • Definition: Areas characterized by intermediate soil moisture content; moist yet well-drained.

  • Mineral soil:

    • Definition: Soil consisting mainly of mineral components over organic matter.

  • Muck:

    • Definition: A well-decomposed organic material where individual plant parts are no longer distinguishable.

  • Neutral pH soil:

    • Definition: Soil with a pH of 7.0, neither acidic nor basic.

  • Organic matter (SOM):

    • Definition: Material originating from decayed organisms; often referred to as soil organic matter.

  • Parent material:

    • Definition: The underlying geological material from which soils originate.

  • pH:

    • Definition: Stands for ‘potential Hydrogen’ and serves as a measure of acidity or alkalinity; pure water has a neutral pH of 7.

    • Classification: pH < 7 denotes acidity (pH 0 to <7), and pH > 7 denotes basic or alkaline conditions (up to 14).

  • Physiography:

    • Definition: The study of Earth's physical patterns and processes.

  • Residuum:

    • Definition: Soils that have weathered in situ from bedrock and remain untransported.

  • Resistant layer:

    • Definition: Layers of sedimentary rock that exhibit greater resistance to erosion compared to adjacent layers.

  • Sandstone:

    • Definition: A sedimentary rock primarily composed of sand-sized minerals or rock grains.

  • Shale:

    • Definition: A fine-grained sedimentary rock made from clay and silt-sized particles that can be laminated and easily broken into thin sheets.

  • Silt:

    • Definition: Soil composed of fine-grained mineral sediments, with particle sizes ranging between sand and clay (0.074 - 0.002 mm), typically transported by moving water.

  • Stratum (plural: strata):

    • Definition: Refers to a layer of geological rock, soil, or vegetation.

  • Syncline:

    • Definition: A downward fold within rock strata.

  • Talus:

    • Definition: Rock fragments, irrespective of size or shape, found at the base of steep slopes derived from weathering processes.

  • Upland:

    • Definition: Locations characterized by well-drained dry to mesic soils, situated up-gradient from floodplains and lowlands.

  • Xeric:

    • Definition: Describes soils that are very dry and excessively well-drained.