Zonation, Succession & Change in Ecosystems

Flashcards on zonation, succession, and ecosystem change.

What is zonation?

Zonation is the gradual change in species and communities across a landscape based on environmental factors.

Name three environmental factors that can cause zonation.

Elevation, latitude, tidal level (or others from the list).

What is the spray zone in a rocky intertidal zone?

The highest point, usually dry and dominated by hardy plants like lichen.

What organisms dominate the high tide zone in a rocky intertidal zone?

Barnacles, mussels, chitons, limpets, and sea snails.

Where are sea stars, anemones, and sea urchins typically found in a rocky intertidal zone?

Low tide zone.

What are transects used for?

To measure biotic and abiotic factors along an environmental gradient.

What type of graph visually represents the distribution and abundance of organisms?

Kite diagram.

What do kite diagrams show?

Distribution and abundance of species, as well as changes to abiotic factors.

What is ecological succession?

The process of ecosystem change over time, from simple to complex.

What is primary succession?

Succession on newly formed or newly exposed land with no species present.

Give an example of primary succession.

Volcanic rock cooling after eruption.

What is secondary succession?

Succession on bare soil where a pre-existing community was present.

Give an example of secondary succession.

An agricultural field that is no longer used.

What is a seral community (sere)?

A temporary and intermediate stage in ecological succession.

What effect does each seral community have?

Causes changes in environmental conditions, allowing the next community to replace it.

What are pioneer species?

The first species to colonize new land.

Give examples of pioneer species.

Moss and lichen.

What does humus provide to new soil?

Basic soil, it is dead organic matter.

What is a climax community?

The final community formed, containing all the different plant and animal species.

How does energy flow change during succession?

Increases as the ecosystem becomes more complex from a low, initial state.

How does productivity change during succession?

Gross and net productivity increase as the ecosystem becomes more complex during the early stages.

What happens to nutrient cycling during succession?

Becomes more complex as there are more species with unique nutrient requirements and cycling processes.

What is ecological diversity?

Variety of species, genetic variations, habitats, and ecological functions within an ecosystem.

What is ecological resilience?

The ability of an ecosystem to recover after a disturbance.

What does greater diversity in an ecosystem promote?

Greater species redundancy where species perform similar roles.

How can human activities affect succession?

Divert the progression of succession to an alternative stable state.

List three examples of human activities that affect succession.

Burning, agriculture, grazing pressure, resource use (deforestation.)

Why can human activities simplify ecosystems?

Which lead to unstable ecosystems.

What happens if human disturbances are mild?

The ecosystem may be able to recover and return to its original state as long as it is highly resilient.

What can happen to resilient ecosystems like tropical rainforests under human pressure?

Deforestation can transform them into savannas or grasslands.

How can mining affect succession?

Leads to soil erosion and landslides, chemicals can pollute water sources.

How can local bedrock and soil properties affect succession?

The type of bedrock and soil affect nutrient availability and water retention.

How does the shape and structure of the land influence succession?

Influences water flow, drainage patterns, and sunlight exposure, affecting plant growth.

Where are fire adapted ecosystems commonly found?

Typically found in savannahs or Mediterranean scrublands.

How can storms, floods, or droughts shape the direction of succession?

Removing dominant species or altering the landscape and create conditions for new species to establish.

What are top-down effects during succession?

Herbivores and carnivores can have top-down effects on the community structure.

How do primary consumers limit plant growth?

Primary consumers, like grazing animals, can limit plant growth by consuming young plants.

How do keystone species affect the community?

Keystone species often drive changes in succession.

How can human impact affect agricultural fields?

Crop are continuously planted instead of allowing a forest or grassland to regrow.

What is gross productivity (GP)?

The total amount of energy captured by producers through photosynthesis.

What is net productivity (NP)?

The energy that remains after respiration by the producers, which is available for growth and consumption by other organisms.

Why is gross productivity low in the early stages of succession?

Due to harsh environmental conditions & low nutrient availability.

What does net productivity do in the early stages of succession, and why?

It is relatively high since most energy goes to biomass accumulation & there is less respiration.

What happens in the mid-stages of succession?

Soil formation occurs, allowing larger plants like shrubs and trees to establish.

What happens to gross productivity as succession progresses?

More plants are present to carry out photosynthesis.

What slows the increase of net productivity in mid-succession?

Respiration increases as more organisms become part of the system.

What happens to gross productivity in the climax community?

May be high since the large number of producers continue to photosynthesize.

What is the state of net productivity in climax communities and explain why?

Net productivity decreases and approaches zero because most energy is used for respiration.

What is species richness and diversity like in early stages?

Typically low.

What is species richness and diversity like in later stages?

Typically high.

What is the size of the organisms in early stages?

Typical small organisms.

What is the size of the organisms in later stages?

Typical large organisms.

What is soil quality in the early stages?

Poor, little nutrients and organic material.

What is the soil quality in the later stages?

High, nutrient reach & full of organic material.

What is energy flow in the early stages?

Simple and linear.

What is energy flow in the later stages?

Complex and cyclic.

What organisms are dominant in the early stages?

Lichens, mosses, algae, bacteria, and fungi.

What organisms are dominant in the later stages?

Woody plants, trees, and shrubs.

What is stability like in the early stages?

Unstable, prone to disturbance and colonization.

What is the stability like in the later stages?

Stable, resistant to disturbance and colonisation.

What are r-strategists?

Species that produce large numbers of offspring quickly.

Where do r-strategists thrive?

In unstable or early-stage ecosystems (like pioneer communities).

Where do K-strategists thrive?

In stable, long-established ecosystems (like climax communities).

What is the reproductive strategy of r-strategists?

Maximize reproduction in a short amount of time.

What is the survival rate of r-strategist offspring?

Low.

What characteristizes K-strategists?

Have different reproductive strategies that make them suited to different ecological roles. e.g. fewer offspring, parental care.

What type of environment do K-strategists typically live in?

Stable environments where competition for resources is high.

What qualities does an r-strategist display?

High Reporductive Rate, Small body, early maturity ( or other qualities from the associated table).

What qualities does a K-strategist display?

Low Reproductive Rate, Late maturity, Specialist Species ( or other qualities from the associated table).

What is a climax community?

The final, stable stage in ecological succession in equilibrium.

What is the state of populations in a climax community?

Populations of organisms remain relatively stable, and the ecosystem is in balance.

What are some examples of climax communities?

Mature forests like temperate rainforests, or savannas where large mammals dominate.

Why has the traditional idea of the climax community been challenged?

Ecosystems are dynamic and continually changing, which makes it difficult to define a permanent, final stage.

What do alternative stable states show?

How ecosystems are not always predictable and are shaped by chance events.

What does the Vera wood-pasture hypothesis suggest?

Large herbivores naturally prevented forests from completely closing by grazing and creating open spaces.

What can human activities divert in an ecosystem?

Succession by human activity can lead to a plagioclimax.

How can overgrazing affect succession?

Livestock can prevent forests from regenerating.

How can removing top predators affect succession?

Prey populations can grow unchecked and prevent plant regrowth.

What is zonation?

The gradual change in the composition of species and communities across a landscape, based on a gradient of environmental factors.

What is succession?

The process of ecosystem change over time, beginning with newly formed or newly exposed land.

What is resilience in the context of ecosystems?

The ability of an ecosystem to recover after a disturbance.

Define climax community.

The final, stable stage in ecological succession where the ecosystem is in balance.

Name three abiotic factors that influence zonation.

Elevation, latitude, tidal level (or other valid abiotic factors).

What is a kite diagram used for?

Visually representing the distribution and abundance of organisms along a transect.

What are pioneer species, and what role do they play in succession?

The first species to colonize new land, helping to create soil and conditions for other species.

How is gross productivity defined?

The total amount of energy captured by producers through photosynthesis.

What factors contribute to the low gross productivity in early stages of succession?

Harsh environmental conditions, low nutrient availability, and few producers.

What is the relationship between diversity and resilience in ecosystems?

Greater diversity often leads to greater resilience due to species redundancy and genetic variation.

How can human activities impact the natural progression of ecological succession?

By diverting succession and creating alternative stable states.

Provide an example of human activity that disrupts succession in tropical rainforests.

Deforestation and agriculture.

What are some climatic factors that influence succession?

Rainfall, temperature, wind, and extreme temperatures.

How can fire influence succession?

Creating new opportunities for different species to dominate, clearing competing vegetation, and providing nutrient-rich ash.

How do herbivores and carnivores exert top-down effects during succession?

By limiting plant growth through consumption or controlling herbivore populations.

What human influences impact climax communities?

Agriculture, urbanisation, and pollution. .

Define plagioclimax.

Ecosystem remains in a semi-stable state that is maintained artificially, e.g.through grazing or regular mowing.

Describe reproductive strategies of R-strategist.

adapted to maximize reproduction in a short amount of time, especially in environments where resources are temporary or unpredictable .

Where do R-strategist colonize?

bare or disturbed ground and take advantage of the sudden availability of resources like nutrients and sunlight .

Describe reproductive strategies of K-strategist.

fewer offspring but investing more energy into their care they typically live in stable environments where competition for resources is high, so producing fewer offspring and ensuring their survival is a better strategy.

Where can K-strategist be found.

Where ecosystems are fully developed and competition for space, nutrients, and light is intense

What is Vera wood-pasture hypothesis.

Large herbivores, like bison or wild cattle, would have naturally prevented forests from completely closing by grazing and creating open spaces