32.1 Conservation Biology

• Understanding the diversity of life on Earth requires knowledge beyond just the total number of species.

• Conservation biology is a field of biology focused on conserving natural resources for present and future generations.

• Conservation biology involves developing new scientific concepts and sustainably managing Earth's biodiversity for human use.

• Multiple subfields of biology contribute to the concepts of conservation biology.

• Conservation biology supports ethical principles such as the value of biodiversity, the undesirability of extinctions, the benefits of ecosystem interactions, and the importance of evolutionary change.

• Conservation biology is considered a crisis discipline due to the projected loss of 10-20% of Earth's biodiversity in the next 20-50 years.

• It is crucial for everyone to understand the importance and value of biodiversity and how human actions contribute to the extinction crisis.

32.2 Biodiversity

• Biodiversity refers to the diversity of life on Earth in terms of the number of different species.

• Human activities have caused a biodiversity crisis, with many species facing extinction.

• In the US, over 694 animal species and 898 plant species are threatened or in danger of extinction, with habitat loss being the biggest threat.

• Other factors contributing to the crisis include the introduction of exotic species, water and air pollution, and overexploitation of natural resources.

• Biodiversity is highest in the tropics and declines towards the poles, with biodiversity hotspots containing over 50% of all known plant species and 42% of all terrestrial vertebrate species.

• Conservation biology aims to reverse the trend towards extinction and prioritize the protection of hotspots.

• Biodiversity is a valuable resource with both direct and indirect benefits.

Direct Values of Biodiversity

• The direct values of biodiversity include medicines, foods, and other products that benefit humans.

Medicinal Value

• Most prescription drugs in the US were originally derived from organisms.

• Rosy periwinkle from Madagascar is a tropical plant that provides useful medicines.

• Chemicals from this plant treat leukemia and Hodgkin's disease.

• The survival rate for childhood leukemia increased from 10% to 90% due to these drugs.

• Hodgkin's disease is now usually curable.

• Tropical rain forests may have hundreds of additional types of drugs worth several hundred billion dollars.

• Penicillin is derived from a fungus, tetracycline, and streptomycin from bacteria.

• These drugs are indispensable in treating diseases, including certain sexually transmitted diseases.

• Leprosy has no cure, but the bacterium that causes it grows naturally in the nine-banded armadillo.

• Having a source for the bacterium may make it possible to find a potential cure for leprosy.

• Limulus amoebocyte lysate from horseshoe crab blood is used to ensure medical devices are free of bacteria.

• 250,000 horseshoe crabs are used for this purpose annually and then returned to the sea unharmed.

Agricultural Value

• Crops like wheat, corn, and rice were originally wild plants modified to be high producers.

• High-yield, genetically similar strains of these crops are grown worldwide.

• Researchers grew wild rice plants to find a gene for resistance to a virus devastating cultivated rice crops in Africa.

• Wild rice plants were used in a breeding program to transfer the resistance gene into high-yield rice plants.

• Biological pest controls, like natural predators and parasites, are often preferred over chemical pesticides.

• Farmers used natural enemies of the brown planthopper when it became resistant to pesticides, saving over $1 billion.

• Cotton growers in Peru used natural predators against the cotton aphid when pesticides no longer worked.

• Most flowering plants are pollinated by animals like bees, wasps, butterflies, beetles, birds, and bats.

• The honeybee is domesticated and pollinates almost $10 billion worth of food crops annually in the US.

• Mites have wiped out over 20% of the commercial honeybee population in the US.

• Wild pollinators are valued at $15 billion a year in the US agricultural economy.

Consumptive Use Value

• We have had successful cultivation of crops, domestication of animals, and tree plantation.

• The environment provides other products sold in marketplaces worldwide.

• Products include wild fruits and vegetables, skins, fibers, beeswax, and seaweed.

• Some people obtain meat directly from the environment.

• The economic value of wild pigs in the diet of native hunters in Sarawak, East Malaysia, is about $40 million per year.

• Species-rich forest in the Peruvian Amazon is worth more if used for fruit and rubber production than for timber production.

• Fruit and latex can be brought to the market for an unlimited number of years.

• Once trees are gone, no more forest products can be harvested.

Indirect Values of Biodiversity

• Wild species have important roles in ecosystems.

• Preserving entire ecosystems is more beneficial than saving individual species.

• Ecosystems provide indirect services that cannot always be measured economically.

• These services are called indirect values.

• Indirect values are wide-ranging and not easily perceptible.

Maintaining Biogeochemical Cycles

• Ecosystems are characterized by energy flow and chemical cycling.

• Biodiversity within ecosystems contributes to the functioning of biogeochemical cycles.

• Biogeochemical cycles include water, carbon, nitrogen, phosphorus, and others.

• Human activities can upset one aspect of a biogeochemical cycle, affecting other parts within the cycle.

• Freshwater, removal of carbon dioxide from the atmosphere, uptake of excess soil nitrogen, and provision of phosphate are dependent on biogeochemical cycles.

• Technology cannot artificially contribute to or replicate any biogeochemical cycle.

Waste Disposal

• Decomposers break down dead organic matter and other types of waste into inorganic nutrients, which are used by the producers within ecosystems.

• Decomposition helps humans by breaking down waste material dumped into natural ecosystems each year.

• Without decomposition, waste would cover the entire surface of the planet.

• Sewage treatment plants are expensive, and few break down solid wastes completely into inorganic nutrients.

• It is more efficient to water plants and trees with partially treated wastewater and let soil bacteria cleanse it completely.

• Biological communities can break down and immobilize pollutants, such as heavy metals and pesticides.

• Wetlands in Canada have a value of $50,000 per hectare per year for their ability to purify water and take up pollutants.

Provision of Fresh Water

• Few terrestrial organisms can live in salty environments and require fresh water.

• The water cycle continuously supplies fresh water to terrestrial ecosystems.

• Humans use fresh water for various purposes, including drinking and irrigation.

• Freshwater ecosystems, such as rivers and lakes, provide fish and other organisms for consumption.

• Freshwater has no substitute, and desalination is four to eight times more expensive than acquiring fresh water via the water cycle.

• Forests and natural ecosystems have a "sponge effect" that absorbs and releases water at a controlled rate.

• Plant foliage and dead leaves in natural areas lessen the impact of rain, and soil absorbs it slowly.

• Forests reduce the possibility and degree of flooding by holding water.

• Marshlands outside Boston, Massachusetts, have an estimated value of $72,000 per hectare per year solely for their ability to reduce floods.

• Forests release water slowly for days or weeks after rains have ceased.

• Rivers flowing through forests release twice as much water halfway through the dry season and three to five times as much at the end of the dry season, showing the water-retaining ability of forests.

Prevention of Soil Erosion

• Intact terrestrial ecosystems naturally prevent soil erosion and retain soil.

• Deforestation can lead to soil erosion and loss of soil retention.

• The Tarbela Dam in Pakistan is losing storage capacity due to silt buildup caused by deforestation upriver.

• Deforestation is causing silt to smother the mangrove ecosystem in the Philippines, which serves as a nursery for many marine species.

• Deforestation upriver is causing a decline in the productivity of coastal ecosystems.

Regulation of Climate

• Trees provide various benefits at the local and global levels, such as:

  • Local-level benefits:

    • Provide shade.

    • Block drying winds.

    • Reduce the need for fans and air conditioners during summer.

  • Global level benefits:

    • Regulate climate by taking up carbon dioxide, a greenhouse gas.

    • Trees store carbon in their wood through photosynthesis.

    • Cutting and burning trees releases carbon dioxide into the atmosphere.

    • Deforestation reduces the amount of carbon dioxide removed from the atmosphere, amplifying the buildup of greenhouse gas.

    • Deforestation removes soil nutrients needed for future tree generations, limiting reforestation.

Ecotourism

• Almost everyone prefers to vacation in natural ecosystems.

• Nearly 100 million people in the US enjoy vacationing in natural settings.

• People spend almost $5 billion each year on fees, transportation, lodging, and food for natural vacations.

• Tourists engage in activities such as sport fishing, whale watching, boat riding, hiking, and bird watching.

• Some tourists want to immerse themselves in the beauty of natural environments.

• Less-developed countries are realizing the economic potential of developing their ecotourism industry.

32.3 Resources and Environmental Impact

• Humans use resources to meet their basic needs.

• Maximally used resources are land, water, food, energy, and minerals.

• Resources can be renewable or nonrenewable.

• Nonrenewable resources are limited in supply and can be exhausted.

• Renewable resources are unlimited in supply, but overconsumption must be avoided.

• Pollution is any alteration of the environment in an undesirable way.

• Pollution is often caused by human activities.

• Human impact on the environment is proportional to population size and resource consumption.

• Consumption of mineral and energy resources has grown faster than population size.

• People in more-developed countries use a disproportionate amount of these resources.

Lands

• People need a physical place to live.

• There are more than 47 people per square kilometer of available land worldwide.

• This includes Antarctica, mountain ranges, jungles, and deserts.

• The land is also needed for other purposes, such as agriculture, electric power plants, manufacturing plants, highways, hospitals, and schools.

Beaches and Human Habitation

• 40% of the world's population lives within 100 km of a coastline, with this number increasing each year.

• In the United States, over half of the population lives within 80 km of the coasts (including the Great Lakes).

• Living right on the coast accelerates natural beach erosion and loss of habitat for marine organisms.

• An estimated 70% of the world’s beaches are eroding.

• Humans often participate in activities that divert more water to the oceans, contributing to rising seas and beach erosion.

• Coastal wetlands serve as spawning areas for fish and other forms of marine life, buffers against hurricane storm surges, and reduce shoreline erosion.

• Humans often try to stabilize beaches by building groynes and seawalls, but they can increase erosion.

• Coastal pollution is a significant problem due to toxic substances placed in freshwater lakes, rivers, and streams that may eventually find their way to a coast, and oil spills at sea can cause localized harmful effects.

Semiarid Lands and Human Habitation

• 40% of Earth's lands are deserts, and adjacent lands are in danger of becoming deserts if not managed properly.

• Desertification is the conversion of semiarid land to desert-like conditions.

• Desertification often begins with overgrazing by animals, causing the soil to lose its ability to hold rainwater.

• Humans then remove vegetation for fuel or fodder, leading to a desert unable to support agriculture.

• Nearly 75% of rangelands worldwide are in danger of desertification.

• The famine in Ethiopia during 2002-2003 was partly due to land degradation that made it unable to support humans and livestock.

Tropical Rain Forest and Human Habitation

• Deforestation is the removal of trees that reduces the extent of a forest.

• It has allowed humans to live in areas where forests once covered the land.

• People are settling in tropical rainforests, such as the Amazon, following the building of roads.

• The soil in the tropics is often thin and nutrient-poor because all the nutrients are tied up in the trees and other vegetation.

• When the trees are felled and removed, and the land is used for agriculture or grazing, it quickly loses its fertility and becomes subject to desertification.

• Deforestation causes a loss of biodiversity and an increase in atmospheric carbon dioxide.

• The trees that once took in and stored carbon dioxide have been removed.

• The destruction of tropical rainforests causes the extinction of a large number of species that have value to humans.

Water

• Access to clean drinking water is a human right.

• Most fresh water is used by agriculture and industry.

• In the US, 39% of fresh water is used to irrigate crops.

• Increased demand for water is due to industrial activity and irrigation-intensive agriculture.

• Irrigation-intensive agriculture supplies 40% of the world's food crops.

• In more-developed countries, more water is used for bathing, flushing toilets, and watering lawns than for drinking and cooking.

• In water-poor areas, people may not have access to clean drinking water.

Increasing Water Supplies

• Although the renewable supply of the world's water meets the needs of the human population overall, certain regions face water scarcity.

• 40% of the world's land is desert, and deserts are bordered by semiarid land.

• Freshwater supply is increased by damming rivers and withdrawing water from aquifers to support human population growth.

• Dams catch 14% of all precipitation runoff, provide water for up to 40% of irrigated land, and give some 65 countries more than half their electricity.

• Damming of certain rivers has been so extensive that they no longer flow as they once did.

• Dams have drawbacks such as water loss due to evaporation and seepage, salt buildup, sediment buildup, and negative impact on native wildlife.

• People are pumping vast amounts of water from aquifers to meet their freshwater needs.

• Groundwater depletion has become a problem in many areas of the world, causing subsidence and sinkholes.

• Saltwater intrusion is another consequence of groundwater depletion, reducing the supply of fresh water along the coast.

Conservation of Water

• By 2025, two-thirds of the world's population may face serious water shortages.

• Solutions for expanding water supplies are available.

• Drip irrigation delivers more water to crops and saves about 50% over traditional methods while increasing crop yields.

• Drip systems are used on less than 1% of irrigated land despite being developed in 1960.

• Most governments heavily subsidize irrigation, giving farmers little incentive to invest in drip systems or other water-saving methods.

• Planting drought- and salt-tolerant crops would decrease the water required for agriculture.

• Recycling water and adopting conservation measures could help the world's industries cut their water demands by more than half.

Food

• In 1950, the human population was 2.5 billion, and there were less than 2,000 calories per person per day.

• Now, with over 7.4 billion people, the world food supply provides more than 2,500 calories per person per day.

• Food comes from growing crops, raising animals, and fishing the seas.

• Modern farming methods have increased the food supply but include harmful practices:

  1. Monoculture planting leads to a lack of genetic diversity and vulnerability to disease.

  2. Heavy use of fertilizers, pesticides, and herbicides contributes to water pollution and soil fertility reduction.

  3. Generous irrigation may lead to the depletion of aquifers.

  4. Modern farming methods rely heavily on fossil fuel energy.

Soil Loss and Degradation

• Land suitable for farming and grazing is being degraded worldwide.

• Topsoil is the richest in organic matter and supports grass and crops.

• Soil erosion occurs when bare soil is acted on by water and wind, causing topsoil loss.

• Marginal rangeland becomes desert, and farmland loses productivity due to soil erosion.

• Planting the same crop in straight rows causes high rates of soil erosion in the US and Canada.

• Conserving lost nutrients could save farmers $20 billion annually in fertilizer costs.

• Eroded sediment ends up in lakes and streams, reducing aquatic species’ survival.

• Salinization, an accumulation of mineral salts generated through irrigation, affects 25-35% of irrigated western croplands.

• Salinization makes land unsuitable for growing crops.

Green Revolutions

• In 1950, the world population was 2.5 billion, and the food supply was less than 2,000 calories per person per day. Now, with over 7.4 billion people, the world food supply provides more than 2,500 calories per person per day.

• Food comes from three activities: growing crops, raising animals, and fishing the seas.

• Modern farming methods have increased the food supply but include harmful practices such as monoculture, heavy use of fertilizers, pesticides, and herbicides, generous irrigation, and excessive fuel consumption.

• The green revolution began about 50 years ago when research scientists began to breed tropical wheat and rice varieties specifically for farmers in the LDCs.

• The green revolution helped the world food supply keep pace with the rapid increase in world population, but most of these plants require high levels of fertilizer, water, and pesticides in order to produce a high yield.

• Genetic engineering can produce transgenic plants with new and different traits, among them resistance to both insects and herbicides.

• Genetically engineered crops are resulting in another green revolution, but some people are opposed to their use, fearing that they will damage the environment and lead to health problems in humans.

Domestic Livestock

• The green revolution was a dramatic increase in yield due to the introduction of new tropical wheat and rice varieties around the world, specifically for farmers in LDCs.

• Most of these plants are called "high responders" because they require high levels of fertilizer, water, and pesticides to produce a high yield.

• Genetic engineering can produce transgenic plants with new and different traits, such as resistance to insects and herbicides and tolerance to salt, drought, and cold.

• A low-protein, high-carbohydrate diet consisting only of grains can lead to malnutrition, especially in LDCs, where kwashiorkor, a condition caused by a severe protein deficiency, is seen in infants and children ages 1-3.

• In MDCs, many people tend to have more than enough protein in their diet due to the large percentage of fossil fuel, fertilizer, water, herbicides, and pesticides used for raising livestock.

• Raising livestock accounts for much of the pollution associated with farming, and it is extremely energy-intensive in MDCs.

• It is possible to feed 10 times as many people on grain as on meat.

Fishing

• World fish catch has been declining since 2000.

• Between 1970 and 1990, the number of large fishing boats doubled to 1.2 million worldwide.

• The US fishing fleet grew due to federal loans for building fishing boats.

• New fishing boats have sonar, depth recorders, and computers to remember previous catch sites.

• Helicopters, planes, and satellite data are used to find fish.

• The number of North Atlantic swordfish caught in the US declined 70% from 1980 to 1990, and the average weight fell from 115 to 60 pounds.

• The Atlantic bluefin tuna is overfished and may become extinct.

• Modern fishing practices negatively impact biodiversity due to bycatch.

• The world's shrimp fishery has an annual catch of 1.8 million tons, but 9.5 million tons of other animals are caught and discarded.

• Aquafarming has reduced fishing pressures on wild populations, with over 90% of shrimp in the US produced via aquaculture.

Energy

• 6% of the world's energy supply comes from nuclear power, and 81% comes from fossil fuels.

• The nuclear power industry has not fulfilled a significant portion of the world's energy needs due to concerns about potential disasters at nuclear power plants and radioactive wastes.

• Oil, natural gas, and coal are fossil fuels.

• MDCs consume more than twice as much fossil fuel as LDCs, but there are more people in LDCs.

• Each person in MDCs uses approximately as much energy in a day as a person in an LDC does in a year.

• Oil burns more cleanly than coal, which may contain a considerable amount of sulfur.

• The burning of any fossil fuel contributes to environmental problems because pollutants are emitted into the air.

• The burning of fossil fuels is elevating the concentration of greenhouse gases in the atmosphere.

• The elevation of carbon dioxide in the atmosphere is contributing to global warming and global climate change.

• The oceans absorb a large amount of the excess carbon dioxide in the atmosphere, making them susceptible to warming and acidification.

Renewable Energy Sources

• Renewable Energy Sources:

  • Wind power.

  • Hydropower.

  • Geothermal energy.

  • Solar energy.

• Wind Power:

  • Expected to account for a significant percentage of future energy needs.

  • Community-generated electricity can be sold to a local public utility.

  • Solves the problem of uneven energy production.

• Hydropower:

  • Converts energy from falling water into electricity.

  • Accounts for 6% of electric power generated in the US.

  • Enormous dams have detrimental environmental effects.

  • Small-scale dams generate less power but have less environmental impact.

• Geothermal Energy:

  • Radioactive decay of elements heats surrounding rocks.

  • Steam and hot water are produced when rocks are in contact with underground streams or lakes.

  • Steam can be piped up to the surface for home heating or to run steam-driven turbogenerators.

  • California's Geysers project is the world's largest geothermal electricity-generating complex.

• Solar Energy:

  • Diffuse energy that must be collected, converted, and stored.

  • Passive solar heating is successful with proper building orientation and insulation.

  • Photovoltaic cells generate electricity that can be used or sold to power companies.

  • Scientists working on using solar energy to extract hydrogen from water via electrolysis.

  • Hydrogen can be used as a clean-burning fuel.

  • Fuel cells use hydrogen to produce electricity and power vehicles.

  • Advantages of solar-hydrogen revolution: no dependence on oil and reduction of environmental problems.

Minerals

• Minerals are nonrenewable raw materials found in the Earth's crust.

• They can be mined and used by humans.

• Nonrenewable minerals include fossil fuels, nonmetallic raw materials (sand, gravel, phosphate), and metals (aluminum, copper, iron, lead, gold.)

• Nonrenewable resources are subject to depletion.

• We can extend our supply of fossil fuels by conserving our use, recycling metals, and finding new reserves.

• Huge machines in the US can remove mountaintops to reach minerals.

• This process causes the land to become devoid of vegetation and allows toxic waste deposits to wash into nearby streams and rivers.

• Legislation requires strip miners to restore the land to its original condition, which can take years to complete.

Other Sources of Pollution

• Synthetic organic compounds and wastes are pollutants of concern.

• Synthetic organic compounds are used in the production of plastics, pesticides, herbicides, cosmetics, coatings, solvents, wood preservatives, and other products.

• Halogenated hydrocarbons are a type of synthetic organic compound that includes chlorofluorocarbons (CFCs) which have caused a thinning of the Earth's ozone shield.

• Hydrofluorocarbons are expected to replace CFCs in coolants and other products.

• Rachel Carson's book Silent Spring made the public aware of the harmful effects of pesticides.

• Industrial wastes are generated during the mining and production of a product.

• Clean-water and clean-air legislation in the United States in the early 1970s prohibited venting of industrial wastes into the atmosphere and flushing them into waterways.

• The use of deep-well injection, pits with plastic liners, and landfills led to much water pollution and human illness, including cancer.

• The Environmental Protection Agency (EPA) oversees the cleanup of hazardous waste disposal sites in the United States.

• Industrial wastes can affect the endocrine system and interfere with reproduction.

• Decomposers are unable to break down these wastes, leading to biological magnification.

• Sewage can contribute to oxygen depletion in lakes and rivers and serve as a fertilizer for plants, leading to eutrophication.

• Sewage treatment plants use bacteria to break down organic matter into inorganic nutrients, such as nitrates and phosphates, which then enter surface waters.

32.4 Sustainable Societies

• A sustainable society is able to provide the same goods and services for future generations of humans as it does now while preserving biodiversity.

Todays Society

• Human society is not sustainable due to the following reasons:

  • A significant portion of land is being used for human purposes, which affects natural ecosystems.

  • Agriculture requires large inputs of nonrenewable fossil fuel energy, fertilizer, and pesticides, leading to pollution.

  • More fresh water is used in agriculture than in homes.

  • At least half of the agricultural yield in the United States goes toward feeding animals, which is inefficient as it takes 10 pounds of grain to grow 1 pound of meat.

  • Animal sewage pollutes water.

  • Fresh water is a renewable resource, but we are running out of the available supply.

  • Our society uses primarily nonrenewable fossil fuel energy, leading to acid precipitation, smog, and various other pollutants entering the ecosystems.

  • Minerals are nonrenewable resources, and the mining, processing, and use of minerals are responsible for much environmental pollution.

Characteristics of a Sustainable Society

• Natural ecosystems can provide insights into sustainable human societies.

• Natural ecosystems use renewable solar energy and cycle materials and return nutrients to producers.

• Sustainable societies should use renewable energy sources and recycle materials.

• These principles can be applied to both rural and urban areas.

• In rural areas, the preservation of ecosystems, agricultural land, and renewable resources is important.

• Topsoil preservation and replanting with native grasses is necessary.

• Cover crops, multiuse farming, and replenishing soil nutrients through composting are methods to increase organic matter in soil.

• Low-flow irrigation, retention ponds, and contour farming can conserve water.

• Precision farming and integrated pest management can reduce habitat destruction and pests.

• Planting a variety of species, including native plants, can reduce dependence on traditional crops.

• Multipurpose trees can provide numerous products and functions.

• Wetlands should be maintained and restored to protect valuable fish species and deltas.

• Renewable forms of energy should be used.

• Supporting local farmers, fishermen, and feed stores by buying locally-produced food products is important.

Urban Sustainability

• More people are moving to cities.

• Methods to make cities more sustainable:

  • Create energy-efficient transportation systems.

  • Use solar or geothermal energy to heat buildings.

  • Cool buildings with air conditioning system that uses seawater.

  • Utilize green roofs to assist in temperature control, supply food, reduce rainwater runoff, and create visual appeal.

  • Improve storm-water management by using sediment traps, artificial wetlands, and holding ponds.

  • Increase the use of porous surfaces for walking paths, parking lots, and roads.

  • Plant native species that attract bees and butterflies and require less water and fertilizers.

  • Create greenbelts with walking and bicycle paths.

  • Revitalize old sections of a city before developing new sections.

  • Use lighting fixtures that hug walls or ground and send light down.

  • Control noise levels by designing quiet motors.

  • Promote sustainability by encouraging the recycling of business equipment and using low-maintenance building materials.