Unit 3 Flashcards
(31 cards)
Environmental problems + impact - Salinisation of soil (water cycle)
Cause: irrigation + land clearing, reduced tranpiration, brings salt to the surface
Impacts:
- seed germination fails
- reduced plant diversity
- alters food web by removing producers
Magnitude: regional
Duration: Long term
Speed: gradual
Stratified sampling: purpose
To represent a diverse ecosystem by dividing the area into strata and collecting samples
Used for:
- estimating population size/density
- measuring distobution + biodiversity
- identifying environmental gradient/zonation/stratification
Carrying capacity
The size of the population that can be supported indefinitely on the available resources and services of that ecosystem
KEYSTONE
A plant or animal that plays a unique and crucial role in the way an ecosystem functions
Eco succession: types
Primary: on newly formed, lifeless terrain (lava flows). Develops over long time scales.
Secondary: on previously inhibited areas disturbed (after fire). Faster than primary.
Environmental problems + impact - Eutrophication (nitrogen cycle)
Cause: fertiliser runoff - nutrient buildup in water
Impacts:
- Algal blooms, nighttime respiration deplete oxygen
- Aquatic life dies, reduced biodiversity
- disrupts aquatic food webs
Magnitude: local to regional
Duration: medium to long term
Speed: rapid after heavy rainfall or runoff
Concept of ecological succession
Natural process of change in an ecosystem’s structure over time: occurs in stages (seres) from initial to stable
Ecological succession: stages (seres)
Pioneer: first (lichen) colonises bare or disturbed land (unstable)
Intermediate: Plants and animals increase as soil improves. Allows for more complex species
Climax: Stable (forest), diverse species + develop micro habitats
Features of pioneer species that make them effective colonisers
Face high light, low water retention and nutrient-poor soil; therefore, be autotrophic + opportunistic
- tolerate extreme abiotic conditions
- photosynthesize
- fix nitrogen
- short life cycle, rapid reproduction ( r-strategist)
- efficient seed dispersal and rapid germination under limiting conditions
Ecological niche
The role and space that an organism fills in an ecosystem, including all its interactions with biotic and abiotic factors
Fundamental: theoretical/potential niche if there were no other species to compete/interact with
Realized: the actual niche which has been constraned due to species interactions
Keystone
This can encompass all interactions the species has with biotic and abiotic factors
- Removal of the keystone triggers a cascade effect of events leading to ecosystem collapse
Structural role: engineers (coral in coral reefs)
Top order consumers: carnivores
Symbiotic role: mutualists
Environmental problems + impact - enhanced global warming (carbon cycle)
Cause: burning fossil fuels, land clearing
Impacts:
- alters the global climate
- habitat loss
- species migration/extinction, reduce biodiversity
Magnitude: global
duration: very long term
speed: accelerating due to industrial population growth
Productivity
The rate of biomass production in an ecosystem/level
Biomass
The total mass of organic matter making up a group of organisms
- protein, lipids, nucleic acids, and carbs in living organisms
*Chemical energy is stored in the bonds of these molecules
Stratified sampling: minimising bias
- Sampling methods: random (generated) or synthetic (regular intervals)
- use a representative number of samples
- ensure correct counting criteria (individual counts, % cover)
- Calibrate equipment and more errors
Abiotic factors to compare ecosystems across temporal and spatial scales
Zonation: distribution patterns along abiotic gradients (temp and N changes). Useful across location, distance and temporal (change over time)
Stratified sampling: divides ecosystems into strata based on abiotic conditions
How environmental factors limit the distribution and abundance of species
Abiotic factors (temp, humidity, light, water) vary.
Optimal: thrive and reproduce (outside this range, population decreases)
Tolerance: struggle to reproduce and stress (outside this range, can’t survive)
Therefore limiting factor for distribution and abundance
Biodiversity
The total variety of organisms, habitats, communities and ecological processes.
Environmental problems + impact - biomagnification (food web dynamics)
Cause: use of non-biodegradable chemicals
Impact
- chemicals in the food chain
- affects the health of top predators, decreased population and diversity
Magnitude: species and ecosystem-specific
Duration: long-lasting
Speed: slow building but long-lasting
The effect of changing the limiting factors of carrying capacity
Density independent: impact regardless of size causing a sudden decline
Density dependent: increases the effect depending on size, naturally regulating numbers
increased CC: increased food, decreased predators, stable climate
decreased CC: habitat loss, drought, overhunting
Environmental resistance: the total of all the environmental limiting factors
Why carrying capacity is determined by limiting factors
It’s dynamic and varies over time due to limiting factors like climate, predators and competition. If a critical resource becomes scarce,e the population may exceed carrying capacity, leading to a crash.
Depends on the availability of the most limited resource
Coral reef - eco management
Water depth, salinity, and species present
Management: decrease coral bleaching and overfishing
Productive soils - eco management
Fertility, structure and biological activity
Management: agricultural practices to protect soil health and food production
Old-growth forest - eco management
Based on age, species richness and undisturbed structure
Management: ban logging (biodiversity and carbon storage)
