Ecosystems

Flashcards about Ecosystem Stability and Change

What features of ecosystems allow stability over unlimited time periods?

Ecosystems cycle nutrients efficiently, contain genetically diverse organisms, and have the means to collect sufficient energy through photosynthesis.

What changes caused by humans threaten the stability of ecosystems?

Human intervention can be devastating, fueled by population growth, reliance on fossil fuels, and plastic pollution.

What is a sustainable ecosystem?

A sustainable ecosystem is one that supports itself without any outside influences

How does the Amazon rainforest largely become its own source of moisture?

Transpiration from vast plant life provides water for the rainforest.

Where does the energy supply for ecosystems originate?

Light harnessed by photosynthesis.

What happens when a tree is logged in the Amazon and then removed from the forest?

The carbon, phosphorus, and nitrogen within the tree are no longer available to the forest ecosystem.

How does genetic diversity within a species provide protection against cataclysmic events?

A varied gene pool provides alleles that may allow a species to survive disease, harsh climatic events or a sudden increase in predators.

What are examples of human activities causing global climate changes that are pushing climatic variables outside many tolerance levels?

Severe droughts and temperature increases.

What is the motivation to cut and clear the Amazon rainforest?

Logging, agriculture, and ranching.

How does the Amazon rainforest influence its own weather and climate?

An incredibly large ecosystem like the Amazon rainforest influences its own weather and climate.

Why are many fires purposely set in the Amazon rainforest?

Brazil is the largest beef exporter in the world, and much of the cleared land there is used to grow soy, a large percentage of which is used to feed the cattle.

What kind of environment does a Winogradsky column create?

It creates an environment that encourages the growth of different types of bacteria in various layers.

What are the IB experimental guidelines regarding use of animals in mesocosms?

Nature of Science: The IB experimental guidelines do not permit the use of animals in an environment that is possibly harmful to their health.

What impact does a keystone species have on other species of an ecosystem?

A keystone species has a major impact on other species of an ecosystem regardless of their own population size.

What can the loss of a keystone species lead to?

Loss of a keystone species can lead to collapse of an ecosystem.

What does sustainability depend on regarding natural resources?

Sustainability depends on the rate of harvesting being lower than the rate of replacement.

How is sustainable harvesting promoted?

Sustainable harvesting is promoted by informed consumer demand.

What characteristic of hardwoods makes selective logging imperative?

Hardwoods of all species are slow growing trees.

What makes logging of black cherry trees sustainable?

Trees are selected rather than cut down randomly; enough trees are left to produce fruit and seeds for the next generation.

What are the most pressing issues that need to be addressed to make agriculture sustainable?

Soil erosion, leaching, fertilizer use, pollution and the carbon footprint.

How do cover crops reduce soil erosion?

These cover crops reduce the penetrating force of heavy rainfall and their roots help hold the soil in place.

How does the energy-intensive manufacture of chemical fertilizers affect farmers and consumers?

This drives up the cost of the fertilizers and that cost is then passed on to consumers.

What results in pollution from agrochemicals?

Water runoff and the leaching of both fertilizers and chemical pesticides results in pollution of water bodies.

What does the carbon footprint of agriculture include?

The use of petroleum products to run farm machinery; the addition of fertilizers, which often are made from petroleum products; clearing natural forest land and other ecosystems to create farmland; the transportation of crops grown in one area of the world to another.

What fertilizers must be water soluble in order to be absorbed by plants?

Fertilizers containing phosphorus (phosphates) and nitrogen (nitrates) must be water soluble in order to be absorbed by plants.

How does biomagnification occur?

Each trophic level typically consumes many organisms from the previous trophic level.

What is biomagnification?

Harmful substances in the environment build up in the organisms towards the top of a food chain.

What are the health effects of mercury accumulation in the body?

Mercury accumulation in the body can have many severe health effects, including neurological damage.

Why was DDT usage problematic?

DDT was indiscriminate in which insects it killed.

When were actions taken to regulate DDT use?

Regulatory actions regarding DDT use began in the 1950s and by 1972 the Environmental Protection Agency in the United States banned the use of DDT for almost all applications.

Why are plastics persistent in the natural environment?

Plastics are persistent in the natural environment due to non-biodegradability.

Why is plastic pollution a global problem?

Plastics are not biodegradable.

What are rewilding activities?

Rewilding activities are conservation efforts aimed at restoring and protecting natural processes and wilderness areas.

What methods are used in rewilding?

The reintroduction of apex predators and other keystone species; establishing wildlife corridors, to connect habitats over larger areas; stopping agriculture and resource harvesting such as logging and hunting; minimizing human influences on an ecosystem, including using ecological management techniques.

What is ecological succession?

Ecological succession is the change over time in the species that live in an area. It is triggered by changes in the abiotic (non-living) and biotic (living) factors in an ecosystem.

What are different types of succession events?

Primary succession, when new land is created and a series of communities emerge, any one community prepares the land for the next type of community; secondary succession, when an existing ecosystem is drastically altered by, for example, fire, flood or human intervention, and the remains of the previous ecosystem are used as a starting point for further changes.

What are common pioneer species in primary succession?

Moss and lichens, both of which are photosynthetic and do not grow root systems.

What characteristics are typical of primary succession progression over time?

Increasing species diversity; increasing size of plants in the community; increasing primary production; more complex food webs; increasing nutrient cycling.

How long does it take for a climax community to develop?

A climax community may take many centuries to develop and will be characteristic of the biome typical of the area.

How are humans are threatening the sustainability of ecosystems?

Deforestation of areas for logging and agriculture