Term 2 Lecture 10: Conservation And Implications Flashcards
Conservation biology
The discipline that aims to understand and alleviate the biodiversity crisis caused by human activity
Biodiversity crisis
We are in a period of mass extinction, species extinction far exceeds typical “background levels”
Natural biomes are being replaced by human ‘anthromes’ characterised by what humans have effected.
50-60% of the earths land surface has been changed by people
Biomes → anthromes
Ecosystems →agro-ecosystems
Physical habitat destruction reduces or removes species population’s, further degredation from other factors including fragmented habitats
Consequences of overexploitation/persecution
Time period/large carnivore
decline/increase
7 years sea otter
Kelp/ urchins
50+ years dingo
Grasses and dusky hopping mouse/
Fox and kangaroo
60+ years gray wolf
Hardwood trees/ elk?
60+ years puma
Hardwoods, non avian reptiles, butterflies/ deer
17 years Lion and leopard
Small primates and ungulates/
Olive baboon
Causes of special loss
Climate change: increase in temperature particularly rapid in the Arctic
Pollution: plastic, light, nutrients (e.g. fertilizers and sewage), sound, CO2 (climate change and increasing ocean acidity)
Invasive species: intrude, establish and increase in abundance outcompeting native wildlife as they lack natural predators/ competition
Problems conservation ecology must overcome
- traditionally only pristine areas are considered - areas in all stages deserve conservation
- lack of communication between academics and practitioners
-placing realistic long-term value on conserving resources (e.g. CO2 sink effect of rainforest)
Conservative ecology must link
Ecological context
Data, mathematic models, concepts, understanding, scientific responsibility
Socioeconomic context
values, interests, information, land and other assets, private sector responsibility
Institutional context
Law, police, authority, land and other assets, public sector responsibility
Conserving a species - considerations
Niche
climate? Resources? Where can it occur?
Requirements for population to persist
Prey? Predators? Competitors? Other habitat requirements? Interactions and human impact?
Smallest population required to allow species survival?
How large should nature reserve be?
How should the reserve be managed?
Potential population growth
Exponential growth: dN/dT = rN
r= rate N= population size T= time
Logistical growth: dN/dT= rN (K-N/K)
K= carrying capacity
then deduct the number of individuals any particular environment can sustain indefinitely (N/K)
When N>K then r is negative
And population declines until N=K
Minimum viable population size for a population to persist is births=deaths
I.e. dN/dT =0
Reserve design
12.9% of total land area on earth is now under protection.
Design involves deciding size, shape, proximity/distribution and effective preservation
→ candidate habitat must support a viable population of the species it is meant to protect
→original ecosystem functions and services of candidate habitat must be mostly intact
One large reserve is better than a few small reserves even if they make up the same total area
Preferable to have a surrounding buffer zone
Reserves connected by habitat corridors are better
Is the reserve big enough? Consider:
- species to area relationship
- Beta-diversity (turnover in species and communities over space)
- species movement
Understanding climate change impacts
Some species are responding to climate change by dispersing and tracking it, expanding or shifting ranges e.g. comma butterfly and Dartford warbler have expanded their ranged whilst three water bird species little egret, purple heron and little bittern recently began to ‘colonise’ the UK
Many species are unable to do this
Climate niche modelling that considers dispersal ability can help us predict species’ responses e.g. comma butterfly has expanded its territory west towards Wales and north towards Scotland in observations since 1970’s and this is expected to continue to new areas that have become climatically suitable but not yet occupied
Models can be tested by introducing a species to an apparently suitable area and seeing if a population persists
Habitat management, creation and restoration
Management: human intervention in an existing habitat to benefit wildlife/ maintain desired species
Restoration: human intervention to aid recovery of a degraded/destroyed environment to a desired former state
Creation: ‘rewilding’ restoration of natural processes and ecological functions in a system
Consider: abiotic conditions, interactions between species and species traits
Disturbance as a conservation tool
At low disturbance competitive exclusion reduces diversity e.g. black walnut kills all surrounding plants and trees
At an intermediate level a balance between disturbance of competition and mortality leads to high diversity
At a high level diversity declines as general mortality rises.
Disturbance can be used to
1) reset succession - reedbeds flooded, cut and scraped to prevent succession to willow and alder woodland
2) reduce dominant species - meadows/grasslands mown or grazed to reduce grass dominance
3) creating heterogeneity- landscape with a diversity of disturbance, ages and habitats will have higher biodiversity e.g. coppicing.
Identifying risk and conservation priorities
- biodiversity hotspots, 25 originally now 36 criteria to be one:
1) at least 0.5% or 1300 vascular plant species endemic
2) has lost at least 70% of primary vegetation
> Identifying areas to prioritise where biodiversity is most at threat
Support ~60% plant, bird, mammal,reptile,amphibian species
Ecosystem services
Nature provides us with:
Clean water
Flood defence
Pollination
Nutrients and soils
Genetic resources
Ecological pest control
E.g. the value of coastal ecosystems such as mangroves to provide protection from extreme storms and tsunamis
