L2: Response to Global Change Flashcards
What is biodiversity? Why is it important?
The variety of animals, plant and organisms in an environment
IMPORTANCE: variety of organisms need to provide diverse functions in different locations at different times of the year
What are essential biodiversity variables (EBVs)?
variables that are monitored to assess biodiversity
1. Genetic composition
2. Species populations
3. Species traits
4. Ecosystem function
5. Community composition
6. Ecosystem structure
What are some challenges associated with biodiversity observations?
- Country biased - better data in more developed countries
- Taxonomic bias - more likely to detect or have better data of vertebrates, less data on insects
- Costly- requires a lot of techniques and variables that makes it costly, meaning there are many gaps
- Time series - requires funding and can be difficult as variables are changing
- Sampling bias - sampling using of presence and not absence. Sometimes sampling effort is known and not random
What are some drivers of biodiversity change?
Land use
- decrease in forest cover 2.3million km squared between 2002 and 2012
Climate change
- 19 of the hottest 20years have been in this century
Fishing
- 33% of fisheries are unsustainable
What are the two main types of models?
Static - represents ecosystem at a single point in time
Dynamic - represents ecosystem and associated changes over time
What are the components of a biodiversity model? What are some challenges?
- Data
- Predictors
- Model patterns and functions
- Predictors
Challenge
- No control as a pristine undisturbed state
- Assumes that interactions and changes are the same throughout time (in reality tipping points could be reached)
- requires biological processes such as metabolism and behaviour
What data is used for species distribution modelling?
- Occurrence records e.g. historical appearances
- Environmental variables e.g climatic suitability
- Co-occurring pests and pathogens to analyse the environmental suitability of new areas and potential for spread
= Can help generate probability of appearance
What are the uses and challenges associated with static-pattern based models?
Uses
- Predict where species will be distributed
- Plan conservation plans by identifying areas at risk
Challenges
- Unable to identify a causal relationship
- Global change is multidimensional
Why are processes important to include within a model?
- Captures biological processes
- Generates better more accurate predictions
- Identify gaps and generate predictions e.g. weather patterns
- Useful for conservation and management
Describe and give an example of a trait-based approach to modelling
Madingley model
- Uses functional traits of organisms to group them, as many species aren’t well described
Groups based on age, energy consumption (diet) etc
What is a cohort based approach to modelling?
Look at traits within a population along with the abundance
What is the Madingley model?
Ecological model designed to simulate the dynamics of an ecosystem
- Uses individual based modelling (IBM) and ecological processes that groups animals together
- Mechanistic so allows integration of human pressures and general functions to be integrated
e.g. Metabolism cohort that is dependent on temperature
Predation that is dependent on model size and body mass of predators
What are the planetary boundaries?
Safe limits for human pressures on 9 critical processes that help maintain Earth’s state
- Passing these limits means surpassing tipping points that can have irreversible effects
Some changes are buffered overtime e.g. extinction rates, climate change, ocean acidification, land-use system
How do people depend on nature?
- Plants release O2
- Plants absorb up to 30% of anthropogenic CO2, limiting global warming
- Further 25% is absorbed by the sea and by calcareous organisms
- Pollination
- Plants and animals provide resources such as food
e.g. fisheries, logging, cattle farming and agriculture
How can biodiversity have a positive effect on ecosystem functions?
Greater variety so greater number of services provided
- Important for nutrient recycling
- increase in diversity leads to increased biomass
- increased pollination success
Selection effects - more species leads to greater competition, selecting for well performing organisms
Complementarity- more likely to have species complementing each other
What evidence is there for the role of higher trophic levels in the Earth system?
C content was found to be affected by the number of mammals
- likely due to their role in feeding and transfer of carbon between different stores
Size selection - historically animals used to be bigger, however, with the changing climate larger animals are at greater risk of extinction
What are the predictions for the future of biodiversity? How accurate are these predictions?
- Decrease in biodiversity due to a combination of land use change and climate change
- Increase in extinction rates and risk, particularly due to habitat loss and climate change
- Homogenisation of communities due to migration of species
Accuracy
- feedback mechanisms are hard to take into account, but likely present and may generate a positive feedback loop
- data quality only shows previous temperatures and land uses, highs that have not really been reached before so hard to predict
- variation of effects on biodiversity is great between different ecosystem types
What is the relevance of fire?
Economic cost - can cause billions of dollars of damage
Agriculture burning - important for land clearing, common method in India for rice fields
Habitat loss - destruction of well developed forest, but also important for resetting and there are trees that are adapted to fires
Biogeochemical reset- nutrient recycling (depending on thermal transformation threshold of certain elements) can increase nutrient availability in soil, but no too frequently
What are the different type of fires?
Surface - burning of shrub and low lying vegetation
Crown - burning of the forest crown (upper canopy). Greater devastation though less common
Ground - burning of material/soil in the ground, hard to control and track
Ladder fuels that help link up to the crown
What types of environments are well adapted to fires and which aren’t?
Savannah’s well adapted
- grasslands that commonly see fire, trees adapted to resprout after fires
Some forests
- Pine and Sequoia rely on fires for underbush clearing and trees are well adapted to regenerate or have a thick bark
Tropical forest NOT well adapted
- not adapted to periodic fire, commonly too humid for fire to spread
Woodlands NOT well adapted
- not commonly exposed to fires so not well adapted
What are the regulators of fire?
- Amount of fuel
- Type of fuel
- Environmental conditions (hot and dry)
- Vapour Pressure Deficit
(difference in the amount of water in the air and how much water the air can hold)
What global changes can increase the risk of and severity of fires? (3)
- Mesophication - shade tolerant trees replace fire resistant trees. Increases risk of a big fire
- Fire-suppression - reduces frequency of fires but increases risk that a big fire will occur and cause greater damage as trees are also less likely to be adapted. Also leads to more fuel accumulating
- Climate change altering weather patterns can increase the amount of lightning strikes, which can start fires
What are novel disturbances?
Change in the intensity and frequency of disturbances as a result of anthropogenic action. To more extreme boundaries and away from historical baselines
What are the three different forms that novel disturbances can take?
- Intensification of the disturbance - larger, longer fires
- Addition of another disturbance - more drought and loss of soil moisture
- Interactions between disturbances (+ve or -ve)
- burning can lead to less fuel and less extreme fires, in addition to reducing competition for water and so increasing soil moisture content