Air pollution- one or more chemicals in sufficient concentration in the air to harm humans, other animals, vegetation or materials.

Arable land- land that can be cultivated to grow crops.

Area sensitive species- plants or animals with very specific habitat requirements that are susceptible to population decline when their habitat is altered.

Biodiversity or biological diversity-the variety of species, their genetic make-up and the natural communities in which they occur

Biome- a major ecological community in a particular terrestrial region comprising certain types of life, especially vegetation, for example various types of desert, grasslands, and forests.

Birth rate- the number of births in a year per 1000 population.

Brownfields- abandoned, idle, or under-used industrial and commercial facilities when expansion or redevelopment is complicated by real or perceived environmental contamination.

Capital- the money or wealth needed to produce goods and services.

Carbon dioxide- a minor constituent of the air, comprising about 0.4% of the atmosphere. It is essential to living systems, released by respiration and removed from the atmosphere by photosynthesis in green plants and by dissolving in seawater. Carbon dioxide levels in the atmosphere have increased since the burning of coal and oil began on a large scale and is a significant greenhouse gas.

Carrying capacity- conventionally defined as the maximum population size of a given species that an area can support without reducing its ability to support the same species in the future.

Community- a collection of living organisms is a defined area that function together in an organized system through which energy, nutrients, and water cycle.

Conservation- the use of natural resources in a way that ensures their continuing availability to future generations; the intelligent use of natural resources for long-term benefit.

Consumer- 1) an organism that obtains energy by feeding on other organisms and/or their remains; usually consumers are classified as primary consumers (herbivores), secondary consumers (carnivores) and micro consumers (decomposers); 2) any person or other entity when using goods for its own needs, neither for resale nor for the manufacture of other goods.

Consumptive activities- forest uses which involve the removal of something from the site (hunting, fishing, timber harvesting). Non-consumptive activities include hiking, bird watching, and nature study.

Culture- a collective noun for the symbolic and learned, non-biological aspects of human society, including language, custom and convention.

Death rate- the number of deaths in a year per 1000 population.

Deforestation- 1) the permanent removal of trees from a forested area 2) the unintentional or intentional conversion of land use from forest to non-forest. Associated with nonrenewable timber harvesting practices in ecologically sensitive areas, such as tropical rainforests.

Demography- the statistical study of human populations, especially with reference to size and density, distribution and vital statistics.

Developing country- the low- and middle-income countries in which most people have a standard of living with access to fewer goods and service lower than most people in high-income countries. There are currently about 125 developing countries with populations over 1 million; in 1995, total population of 4.7 billion.

Disturbance- a natural or human-induced environmental change that alters one or more of the floral, faunal, and microbial communities within an ecosystem. Timber harvesting is the most common human disturbance. Windstorms and fire are examples of natural disturbances.

Ebb and Flow- the motion of going back and forth

Ecological footprint- the area of land (and water) that is required to support the human population of a particular city, region or country at a specified standard indefinitely.

Economic development- improvements in the efficiency of resource use so the same or greater output of goods and services is produced with smaller throughputs of natural, manufactured and human capital.

Ecology- the study of interactions between living organisms and their environment.

Ecosystems- a natural unit comprised of living organisms and their interactions with their environment, including the circulation, transformation, and accumulation of energy and matter.

Ecosystem management- use of ecosystem concepts to predict the effects of management actins on the ecosystem and to guide management planning and actions.

Endangered species- species in danger of extinction throughout all or a significant part of their range. Protection mandated by the United States Endangered Species Act. 1973.

Endangered Species Act- an act passed in 1973 that provides for both the protection and the conservation of threatened and endangered plants and wildlife including fish, mammals, birds, insects, reptiles and amphibians.

Energy conservation- taking care to be efficient in the use of energy so that it is not wasted. By becoming more efficient in the use of energy, the demand for energy can be reduced so that new energy production facilities are not required.

Environment- the sum of all external conditions and influences, living and nonliving, that affect the development and the survival of an organism or group of organisms.

Environmental ethic- the rights and duties of people with regard to the planet Earth.

Extinct- refers to a species that no longer exists. Local extinction occurs when every member of a particular population has died. Global extinction occurs when every member of a species has died.

Extirpation- the eradication of a species from a portion of its natural range.

Fauna- the animals that live in a particular area.

Flora-the plants that live in a particular area.

Forestry- the principles and practices for managing, using, and enjoying forests; forestry includes a broad range of activities: managing timber, fish, wildlife, range and watershed; protecting forests and timber products from diseases, insects and fire; harvesting, transporting, manufacturing, marketing, preserving and protecting wood and other forest products; maintaining water and air quality; and maintaining the well-being of society as it is influenced by forests and other renewable natural resources and their derived products and values.

Fragmentation- the segmentation of a large tract or contiguous tracts of forest to smaller patches, often isolated from each other by non-forest habitat. Results from the collective impact of residential and commercial development, highway and utility construction, and other piecemeal land use changes.

Genotype- growth of development characteristics dependent on genetic information. The genetic constitution of an organism or a species in contrast to its observable characteristics.

Global economy- the emerging international economy characterized by free trade in goods and services, unrestricted capital flows and weakened powers to control domestic economies.

Global warming- the hypothesis that the Earth's atmosphere is warming because of the release of greenhouse gases, such as carbon dioxide. These gases are released into the air from burning gas, oil, coal, wood, and other resources and trap heat in an action similar to that of the walls of a greenhouse.

Globalization- used to describe the ongoing, multidimensional process of worldwide change and the idea that the planet is considered as a whole, rather than individual cultures, continents, or landscapes.

Goods and services- things that are produced by a country's economy, for example goods include food, clothing, machines, and new roads, services include those of doctors, teachers, merchants, construction workers, and government officials.

Grassroots- the lowest level of political activity or action, the voters or citizens themselves; the people who are most directly effected by public policy decisions.

Greenhouse effect- the trapping of heat in the Earth's atmosphere by several greenhouse gases.

Greenhouse gases- gases in Earth's lower atmosphere (troposphere) that cause the greenhouse effect, for example carbon dioxide, chlorofluorocarbons, ozone, methane, water vapor, and nitrous oxide.

Greenways- corridors of open space. They often follow natural features such as rivers, streams or ridges, man-made transportation corridors such as rail lines and canals or utility right-of-way.

Groundwater- water that sinks into the soil and is stored in slowing flowing and slowly renewed underground reservoirs called aquifers.

Growth rate- the change (increase, decrease, or no change) in an indicator over a period of time, expressed as a percentage of the indicator at the start of the period.

Habitat- the area where an animal, plant, or microorganism lives and finds the nutrients, water, sunlight, shelter, living space, and other essentials it needs to survive.

Habitat loss- the process of conversion of a natural ecosystem to degraded system incapable of supporting native wildlife.

Hazardous chemical- chemical that can cause harm because it is flammable or explosive, or that can irritate or damage the skin or lungs or cause allergic reactions of the immune system.

Hazardous waste/Toxic waste- any waste that has the potential to inflict damage on either human health or the natural environment.

Human capital- people and their ability to be economically productive. Education, training, and health care can help increase human capital.

Human rights- privileges claimed or enjoyed by every human being by virtue of being human.

Illiteracy- a person who is illiterate is not able to, with understanding, read or write simple statements about every day life nor do simple mathematical calculations.

Indicator- a statistical measure used to illustrate progress of a country in meeting a range of economic, social and environmental goals. Since indicators represent data that have been collected by a variety of agencies using different collection methods, there may be inconsistencies among them.

Indicator species- species with such specialized ecological needs that they can be used for assessing the quality, condition, or extent of an ecosystem on the basis of their presence and destiny, or the accumulation and effect of materials in their tissues.

Integrated Pest Management (IPM)-control of insect pests using a combination of biological, chemical and silvicultural methods.

Invasive species-a species that is not native to the ecosystem.

Land degradation- term for the decline in soil quality which can occur in a number of ways, including erosion, salinisation, water logging, heavy metal and other chemical pollution , and desertification.

Land ethic- the principles and values guiding our use and treatment of the land. Forest stewardship is a land ethic.

Land recycling- the reuse of land that is unused or underutilized, whether or not it is contaminated.

Literacy- the ability to read and write a simple statement about one's everyday life and do simple mathematical calculations.

Local government- the level of government that is responsible for the day to day running of a ward, district, province or city. Local government responsibilities often include the provision of public transport and public recreational facilities as well as the monitoring and enforcing of many environmental regulations.

Management plan- a document prepared by professionals to guide and direct the use and management of a forest property. It consists of inventory data and prescribed activities designed to meet ownership objectives.

Multiple use and value- a conceptual basis for managing a forest area to yield more than one use or value simultaneously. Common uses and values include aesthetics, water, wildlife, recreation, and timber.

Native species (indigenous species)- a species that occurs naturally in an area or habitat.

Natural resources- raw materials supplied by the Earth and its processes; natural resources include nutrients, minerals, water, plants, animals, etc.

Natural resource accounting- the process of adjusting national accounts such as GNP to reflect the environmental costs of economic production. Although methods are still being developed, natural resource accounting strives to determine the costs of depleting natural resources and damaging the environment.

Niche- the physical and functional location of an organism within an ecosystem; where a living thing is found and what it does there.

Non-renewable resource- substances such as oil, gas, coal, copper and gold, which, once used, cannot be replaced in this geological age.

Organic- 1) describes matter that is living or was once living; 2) describes agricultural products grown or raised without pesticides or other synthetic chemicals.

Over-consumption- the sum of resources at a rate that exceeds the ability of natural processes to replace them.

Ozone layer- layer of gaseous ozone (O3) in the stratosphere that protects life on Earth by filtering out harmful ultraviolet radiation from the sun.

Pesticides- chemicals that kill or inhibit the growth of organisms that people consider undesirable and are harmful to cultivated plants or human health. Fungicides (which kill fungi), herbicides (which kill plants), and insecticides (which kill insects) are types of pesticides.

Phenotype- outward appearance or physical attributes of an organism resulting from both the effects of the environment and genetic makeup.

Physical capital- things, such as machinery, tools, equipment, furniture, parts, and buildings, that are needed to produce goods and services.

Poaching- hunting, trapping, or fishing illegally.

Population- a group of individuals of one plant or animals taxon (species, subspecies, or variety).

Population growth- the increase in a country's population, divided by the population. It reflects the number of births and deaths and the number of people moving to and from a country. Usually expressed as an annual average.

Preservation- the setting aside of areas and resources for limited or restricted use and development; often restricts land use to recreation or scientific study.

Primary good or products- goods - for example iron ore, diamonds, wheat, copper, oil, or coffee - that are used or sold as they are found in nature. Also called commodities.

Potable water- water that is safe to drink.

Producer- organisms that synthesize organic compounds from in organic substances via photosynthesis (by green plants) or chemo-synthesis (by anaerobic bacteria).

Quality of life- the standard of life that an individual enjoys. Quality of life goes beyond simply meaning the material things that make parts of our everyday lives more pleasant or less onerous. It includes such things as environmental health, the satisfaction of relationships with others, dignifying work.

Rare species- species which exist only in one or a few restricted geographic areas or habitats or occur in low numbers over a relatively broad area.

Recycling- the reclamation of potentially useful material from household, agricultural and industrial waste. The goal is to reduce pollution and save energy and costs while slowing down the rate at which non-renewable resources are depleted. As concern for the environment spreads, especially in the industrialized countries, the value of recycling has become more accepted. Recycling is not only good for the environment, it also creates jobs.

Reforestation- the renewal of forest cover by natural regeneration or the planting of seeds or seedlings.

Regeneration- the replacement of one forest stand by another as a result of natural seeding, sprouting, planting, or other methods; also young trees which will develop into the future forest.

Regeneration cut- a timer harvest designed to promote and enhance natural establishment of trees. Even-ages stands are perpetuated bye three types of regeneration cuts: seed tree, shelterwood, and clearcutting. Uneven-aged stands are perpetuated by selecting individual or small groups of trees for removal (e.g., the selection system).

Renewable- able to be replaced or replenished, either by the Earth's natural processes or by human action. Air, water, and forests are often considered to be examples of renewable resources. Minerals and fossil fuels are examples of non-renewable resources.

Renewable resource- a resource that has the capacity to be replaced through natural processes; for example, trees are a renewable resource.

Resources- the machines, workers, money, land, raw materials, and other things that a country can use to produce goods and services and to make its economy grow. Resources may be renewable or non-renewable.

Risk management- the identification, assessment and reduction of risks associated with the activities with which we are involved.

Sanitation- maintaining clean, hygienic conditions that help prevent disease through services such as garbage collection and wastewater disposal.

Seed tree- a tree left behind when a stand is harvested or partially cleared to provide a source of seed for the species desired to be renewed.

Selection cut- a regeneration cut designed to create and perpetuate an uneven-aged forest. Trees may be removed singly or in small groups. A well-designed cut removes trees of lesser quality and trees in all diameter classes along with merchantable and mature high-quality saw-log trees. Should be differentiated from “select†or “selective†cuts, which often equate to high-grading.

Selective cutting/harvesting - the removal of individual or small clusters of trees to manage the forest stand for a mixture of age classes and products.

Shelterwood- a regeneration cut designed to stimulate reproduction by removing all overstory trees. This is achieved by a series of cuts over several years. Gradual reduction of stand density protects understory trees and provides a seed source for stand regeneration.

Silviculture- the art, science, and practice of establishing, tending, and reproducing forest stands; the study of the life history and general characteristics of forest trees.

Social justice- the concept that all people should have equal access to services and goods produced in a community.

Social services- services generally provided by the government that help improve people's standard of living.

Species- a group of organisms that have a unique set of characteristics that distinguishes them from other organisms

Stand- a grouping of vegetation sufficiently uniform in species composition, age, and condition to be distinguished from surrounding vegetation types and managed as a single unit.

Stewardship- the concept of responsible care taking; the concept is based on the premise that we do not own the resources, but are managers of resources and are responsible to future generation for their condition.

Stream management zones- areas adjacent to water bodies where unique management strategies are applied to protect water quality and maintain stream temperature through shading. Zone width is normally 50 feet, but varies according to site.

Succession (or ecological succession)-the process in which communities of plant and animal species in a particular area are replaced over time by a series of different and usually more complex communities; when no previous vegetation exists on a site, the process is called primary succession; when a site supported vegetation previously but was disturbed, the process is called secondary succession.

Sustainability-meeting the needs of the present without compromising the ability of future generations to meet their own needs, while balancing the relationship between ecological integrity, economic prosperity and social equity which requires thinking beyond our immediate needs and interests.

Sustainable agriculture- method of growing crops and raising livestock based on organic fertilizers, soil conservation, biological control of pests, and minimal use of non-renewable fossil-fuel energy.

Sustainable development- development that meets the needs of the people today without compromising the ability of future generations to meet their own needs.

Sustainable forestry- the management of forests to meet the needs of the present without compromising the ability of future generations to meet their own needs.

Sustained yield- the rate at which a resource may be used without reducing its long-term availability or limiting its ability to renew itself.

Symbiotic- refers to an ecological relationship between two organisms. The relationship may be beneficial or detrimental to one or both organisms (see the Three Sisters activity on the 2003 Earth Day poster for an example).

Thinning- cutting in a mature stand to increase its rate of growth, to foster quality growth, to improve composition, to promotes sanitation, to aid in litter decomposition, to obtain greater total yield, and so recover and use material that would be lost to human use otherwise.

Threatened species - a species likely to become endangered in the foreseeable future, throughout all or a significant portion of its range, unless protected.

Urbanization- the process by which a country's population changes from primarily rural to urban. It is caused by the migration of people from the country side to the city in search of better jobs and living conditions.

Waste management- term applied to the processes of determining where and how to dispose of industrial or household waste.

Wastewater- water that has been used and is no longer clean.

Wastewater treatment- the process of removing pollutants from water that has been used.

Water pollution- one or more chemicals in high enough concentration in water to harm humans, other animals, vegetation or materials.

Water quality- the condition of water, especially in relation to its suitability for drinking. Water is safe or unsafe depending on the amount of bacteria in it.

Watershed- the land area fromwhich surface runoff drains into a stream channel, lake, reservoir, or other body of water, also called a drainage basin.  Pennsylvania has 6 major watersheds. 

Wetlands- areas that, at least periodically, have waterlogged soils or are covered with a relatively shallow layer of water such as marshes, swamps, bogs and fens.

Wilderness area- an area established by the federal government to be managed and preserved in a n essentially untouched condition; wilderness areas are open to some recreational activities, but using machinery, mining, logging and pursuing many other commercial activities are generally not allowed.