Define ecosystem.
Enjoying Flashcards?
Tell us what you think
Define ecosystem.
An ecosystem is a community of living (biotic—plants and animals) and non-living (abiotic) elements that interact and work together in the same environment.
What are the two basic functions ecosystems perform?
Ecosystems perform two basic functions:
They cycle nutrients.
They move energy.
True or False?
Ecosystems are closed systems.
False.
Ecosystems are open systems, as flows of energy and materials cross ecosystem boundaries.
What is gross primary productivity (GPP)?
Gross primary productivity (GPP) is the total amount of carbon compounds (biomass) fixed during photosynthesis by all producers in the ecosystem in a given period of time, measured in kg/m2/year.
Define net primary production (NPP).
Net primary production (NPP) is the amount of energy available to herbivores in the plant's biomass after plant respiratory loss. It can be calculated as: NPP = GPP - R (respiratory loss).
What proportion of sunlight energy do plants typically use for photosynthesis?
Only 2% of the light that falls on a plant is used to produce glucose through photosynthesis.
Define a trophic level.
A trophic level is a group of organisms that obtain their food in the same way, e.g. producers, primary consumers, secondary consumers, etc.
What is a keystone species?
A keystone species is any organism (animal, plant, bacteria or fungi) that holds a habitat together. If removed, it sets off a trophic cascade that significantly alters the ecosystem.
True or False?
Energy pyramids account for the size of individual organisms.
False.
The biggest criticism of energy pyramids is that they ignore the size of individuals—an oak tree carries the same weight as an aphid within the pyramid.
What does a food web show?
A food web shows the complex variety of plants and animals which feed on each other, as well as the interdependence of organisms in a community.
Define interdependence in an ecosystem.
Interdependence refers to how each species in a community depends on other species for food, shelter, pollination, seed dispersal, etc. If one species is removed, it can affect the whole community.
What percentage of energy is typically transferred between trophic levels?
Only 10% of energy is typically passed from one trophic level to the next.
What are nutrients in an ecosystem?
Nutrients are chemical and mineral substances derived from rock weathering, decomposition, and precipitation. They include phosphorous, potassium, nitrogen, carbon, sulphur, and trace elements.
Define the Gersmehl diagram.
The Gersmehl diagram is a simple system showing nutrient cycling, including inputs, stores, outputs, and transfers, typically represented with proportional arrows and circles.
What are the main stores in the nutrient cycle?
The main stores in the nutrient cycle are biomass, litter, and soil.
Define biomass in the context of nutrient cycling.
Biomass refers to the total weight of living organisms - plants and animals - in an area, where nutrients are stored.
What is litter in a nutrient cycle?
Litter is the layer of dead plant tissues, dead animals, and animal wastes that accumulate on the ground.
True or False?
Nutrients are always conserved within an ecosystem.
False.
Nutrients can be lost from an ecosystem through runoff and leaching.
In tropical rainforests, which nutrient store is typically the largest?
In tropical rainforests, the nutrient store of biomass is typically huge, with small stores of soil and litter.
In tropical rainforests, why are the soil nutrient stores small ?
The soil store is small in tropical rainforests because high rainfall encourages leaching and the uptake of nutrients is rapid.
In deciduous forests, which nutrient store is typically the largest?
In deciduous forests, the largest store is typically the soil, due to fluctuating climate conditions.
What factor is the main controlling influence on nutrient cycling?
The main controlling factor in nutrient cycling is climate.
How does climate affect nutrient cycling in a tropical rainforest?
In a tropical rainforest, warm and humid conditions lead to larger biomass stores, fast nutrient transfer from sub-surface weathering, and small litter stores due to rapid decomposition.
True or False?
Taiga ecosystems have soil as their largest nutrient store.
False.
In taiga ecosystems, litter is typically the biggest store, as there is a slow transfer due to extreme cold.
What are the two main types of ecosystems?
The two main types of ecosystems are terrestrial (land-based) and aquatic (water-based).
Define terrestrial ecosystem.
A terrestrial ecosystem is an exclusively land-based system, distributed around climatic zones.
True or False?
Every factor in an ecosystem is independent of other factors.
False.
Every factor in an ecosystem is co-dependent on other factors, either directly or indirectly.
What are abiotic factors in an ecosystem?
Abiotic factors are non-living components that influence an ecosystem, such as soil, light, temperature, precipitation, geology, altitude, and latitude.
How does latitude influence ecosystems?
Latitude strongly influences an area's temperature, which produces climates such as polar, tropical, and temperate. This leads to different natural biomes with characteristic species.
What effect does increasing altitude have on vegetation?
As altitude increases, the temperature decreases and growth is slowed. Vegetation tends to be shorter, with fewer species.
Define aspect in the context of ecosystem topography.
Aspect is the direction a slope faces, this determines how much light and warmth vegetation receives for growth.
How does soil drainage affect vegetation?
Poor soil drainage leads to waterlogging and limited plant type and growth (e.g., heather on moorlands).
True or False?
Human-induced changes in ecosystems are always negative.
False.
Human-induced changes can have both positive and negative effects on ecosystems. For example, tree planting can restore local ecosystems affected by deforestation.
What is a positive feedback loop in ecosystem change?
A positive feedback loop is when a change in an ecosystem reinforces further change in the same direction, such as wildfires increasing atmospheric CO2 levels, which strengthen the greenhouse effect and increase the rate of fires in the future.
What are the three main ways species respond to rapid climate change?
Species respond to rapid climate change by:
dying out.
adapting if given time.
moving to areas with more suitable conditions.
According to the IPCC, what percentage of plant and animal life is at risk of extinction with a 1.6 °C temperature rise?
The IPCC estimates that a rise of 1.6 °C will put 20–30% of all plant and animal species at risk of extinction.
How does sea level rise impact coastal ecosystems?
Sea level rise puts coastal ecosystems at risk of being permanently lost and causes saltwater intrusion into freshwater systems, endangering species or forcing them to move inland.
What is the Living Planet Index (LPI)?
The Living Planet Index (LPI) measures the state of the world's biological diversity based on average changes in the population of vertebrate species from terrestrial, freshwater and marine habitats.
True or False?
Climate change impacts are uniformly distributed across Europe.
False.
Climate change impacts vary across different regions of Europe, with some areas experiencing more severe changes than others.
What is the main human activity that has had the biggest impact on ecosystems globally?
Deforestation has had the biggest impact on ecosystems globally, with over 50% of all mature forests lost to logging.
How does urban planning affect ecosystems?
Urban planning can separate natural ecosystems and split populations, disrupting habitats and species interactions.
Define ecological collapse.
Ecological collapse refers to a situation where an ecosystem experiences a drastic, possibly permanent, reduction in carrying capacity for all organisms, often resulting in mass extinction.
What is a trophic cascade?
A trophic cascade is a chain of events triggered by the removal of a keystone species, which can significantly alter the structure and biodiversity of an ecosystem.
How do extreme weather events linked to climate change affect ecosystems?
Extreme weather events like floods and droughts can kill species that are unable to adapt to wetter or drier climates. This disrupts the balance of the ecosystem.