Chapter 6: Humans in the Biosphere

Vocabulary flashcards covering key terms and concepts from the chapter on Humans in the Biosphere. Each card defines a major concept related to ecology, resources, biodiversity, and environmental challenges.

monoculture

The practice of clearing large areas of land to plant a single, highly productive crop year after year; efficient for farming but can deplete soil and reduce biodiversity.

renewable resource

A resource that can be produced or replenished by a healthy ecosystem over time.

nonrenewable resource

A resource that cannot be replenished quickly enough to meet immediate needs (e.g., fossil fuels: coal, oil, natural gas).

sustainable development

Use of natural resources in a way that meets present needs without long-term harm to ecosystems; aims for flexibility and balance.

topsoil

The fertile, nutrient-rich layer of soil essential for plant growth; renewable but slowly formed.

erosion

The removal of soil by water or wind, which can reduce soil fertility and land productivity.

desertification

The process by which productive land becomes desert, often due to drought, erosion, and unsustainable practices; about 40% of Earth’s land at risk.

deforestation

Loss of forests, which can cause soil erosion, biodiversity loss, and climate impacts; old-growth forests are typically nonrenewable.

old-growth forest

Forests that have not been disturbed by recent logging; slow to regenerate and often considered nonrenewable resources.

contour plowing

Plowing along the natural contours of the land to reduce water runoff and soil erosion.

terracing

Shaping land into stepped levels to hold water and soil, reducing erosion on slopes.

crop rotation

Alternating different crops on the same land to maintain soil nutrients and reduce erosion.

selective harvesting

Harvesting only mature trees to preserve forest structure and soil health.

reforestation

Replanting trees in deforested or degraded areas to restore forests.

carrying capacity

The maximum population size that an environment can sustain indefinitely without degrading resources.

Ogallala aquifer

A vast underground water reservoir spanning several U.S. states; slowly being depleted and not readily replenished.

irrigation

Artificially supplying water to crops; can be water-intensive and affect water resources.

point source pollution

Pollution that enters a water body from a single, identifiable source (e.g., pipe, factory).

nonpoint source pollution

Pollution that enters water from many diffuse sources (e.g., runoff from roads, yards).

PCBs

Polychlorinated biphenyls, industrial pollutants that persist in the environment and accumulate in sediments.

heavy metals

Toxic metals (cadmium, lead, mercury, zinc) that can contaminate water and organisms.

DDT

A pesticide that caused widespread harm via biological magnification; banned in many places due to ecological impacts.

biological magnification

Increase in a pollutant’s concentration as it moves up the food chain through organisms.

wetlands

Ecosystems that purify water, filter pollutants, and provide flood control and other services.

drip irrigation

A water-efficient method delivering water directly to plant roots.

keystone species

A species whose presence maintains the structure of an ecological community (e.g., sea otter).

invasive species

Non-native species that spreads rapidly and disrupts local ecosystems and biodiversity.

habitat fragmentation

Breaking up of continuous habitats into smaller, isolated patches, reducing species richness and populations.

biodiversity

The total variety of life in all its forms, levels, and combinations (ecosystem, species, genetic diversity).

ecosystem diversity

The variety of habitats, communities, and ecological processes in an area.

species diversity

The number and variety of species in a given area.

genetic diversity

The variation of genes within a species, contributing to adaptability and survival.

ecological hotspot

Areas with high biodiversity under immediate threat; criteria include at least 1500 native plant species and 70% habitat loss.

habitat

The natural environment in which an organism lives and obtains resources.

CITES

Convention on International Trade in Endangered Species; international treaty restricting trade in endangered species.

AZA SSPs

Species Survival Plans coordinated by the Association of Zoos and Aquariums to protect threatened species via captive breeding and reintroduction.

captive breeding

Breeding of endangered species in captivity to maintain genetic diversity and enable eventual reintroduction.

ecotourism

Sustainable tourism that supports conservation and local communities while protecting biodiversity.

ecological footprint

A measure of the land and water area required to provide resources and absorb wastes for a population.

ozone layer

The atmospheric layer containing ozone that absorbs much of the sun’s harmful UV radiation.

CFCs

Chlorofluorocarbons, ozone-depleting chemicals used in aerosols and refrigerants; largely phased out by international agreements.

Montreal Protocol

International treaty (1987) banning most CFCs to protect the ozone layer.

global warming

Long-term increase in Earth’s average surface temperature due to increased greenhouse gases and other factors.

climate change

Broader changes in climate patterns (temperature, rainfall, and weather) resulting from warming and other factors.