Habitat Loss Flashcards
(30 cards)
1
Q
What are the drivers of habitat loss?
A
- agriculture
- urbanisation
- extractive industries
- aquaculture
2
Q
Solution to threats to biodiversity?
A
- rewilding
- sustainable agriculture
- land sharing vs land sparing
3
Q
What is the greatest threat to biodiversity?
A
Humans
Responsible for declines of nearly 50% of mammals, birds and amphibians (IUCN red list data)
4
Q
Global problem of natural habitats turned into human-dominant habitats?
A
- 50% of land-surface already transformed
- over 2/3 water supplies affected
- 40% oceans affected
5
Q
How does habitat loss happen?
A
- predictable sequence of transition (DeFries et al. 2004)
- Timescale = different in different areas
UK: - presettlement stage end of Neolithic (~5000 ya)
- frontier/subsistence in bronze age
- currently intensive
6
Q
What are the primary drivers of habitat loss?
A
- agriculture
- urbanisation
- extractive industries
- aquaculture
7
Q
Agriculture as a primary driver of habitat loss
A
- 1700-1950; agricultural land = increased from 2.65 to 12 million km2 - a 450% increase over 250 years
- currently uses 40% land surface (over 70% in UK) - 18.7 million km2 = cropland; 33.8 million km2 = pasture
- “Green revolution” - 1930s-1960s (artificial fertilizer, pesticides/herbivores, new crop varieties) avoided mass starvation but led to intensification and expansion of agriculture
8
Q
Agriculture as a primary driver of habitat loss
How can we feed an expanding population?
A
Increase agricultural land
- predicted to need additional 10-20% cropland by 2050 - will reduce natural habitat
Increase crop yields
- may lead to increased pollution, yields may be limited
- need to develop methods that increase yields with less habitat destruction and degradation e.g. robot laser weeders
Change in diets, avoid waste
- meat and dairy products usually require more land (animals have to eat)
May be past the peak of agricultural land use
9
Q
Agriculture as a primary driver of habitat loss
What are examples of certification schemes that exist?
A
- Rainforest Alliance
- Roundtable on Sustainable Palm Oil
- Soil Association
10
Q
Urbanisation as a primary driver of habitat loss
Stats
A
- currently accounts for 3% land
- predicted increase to 9% of land w/ 5 billion people by 2030
- 1.2 million km2 (an area the size of South Africa) is projected to have >75% probability of conversion
- intense urbanisation leads to 55% loss of biodiversity, reaching close to 80% loss in the most extreme cases
11
Q
Urbanisation as a primary driver of habitat loss
How to combat urbanisation?
A
Sustainable development and green infrastructure will be key here:
- many cities are developing green infrastructure plans
- Some cities features more “friendly” to biodiversity than others
- For example, Beninde et al. (2015) showed that biodiversity generally increases when urban habitats:
1. have more green space
2. have a more habitat types
3. have more plant cover
4. are less intensively managed
5. contain water
12
Q
Extractive industries as a primary driver
A
- extracting resources from nature e.g. oil, gas, mining, quarrying, fishing, hunting, forestry
- cause other issues (e.g. pollution, overexploitation) as well as habitat loss
- cause estimated 7% deforestation in subtropics (Finer et al. 2008)
- In North America, oil drilling led to loss of 30,000 km2 land between 2000 and 2012 (3 x area of Yellowstone National Park)
- area damaged may be relatively small but destruction is often complete
13
Q
Aquaculture as a primary driver
A
- fast-growing area - now produces over half seafood
- has advantages but also can destroy habitats
- e.g. mangrove forests - shrimp farming
- over half of mangroves have been lost and 40% of endemic vertebrates are threatened
- but some are being replanted
14
Q
Where is habitat loss happening?
A
- some biomes affected more than others
- FORESTS (average 50% loss over 5000 years)
- most temperate forest already lost
- temperate forests are now expanding (due to reforestation & rewilding)
15
Q
Rewilding
A
- can start small - not always east processes, communication is key
- challenging but possible
- need to take societal concerns on board (e.g. human-wildlife conflict, livelihoods, different stakeholders, public support)
- big UK governmental focus on tree-planting BUT must be the right trees in right place
- e.g. heather and eroding peat; peat hags degraded by historic acid rain, sheep grazing and repeated burning; moorland burning
- e.g. Trees = largely confined to regimented blocks of non-native conifers w/ little or no connection to their surroundings
- e.g. Tiny fragments of broadleaved trees managed to stay, including fledging birch and stream flowing down to the valley floor
- e.g. sheep over-grazed hills - ground = compacted through centuries of trampling - causing bad erosion and landslips, contributes to flood risk already exacerbated by lack of vegetation
16
Q
Rewilding Transition
A
- significantly reduced grazing pressure, seedlings can grow and ground is less compacted
- fewer chemicals, fertilisers and animal medications = entering soil and water
- reducing stocking numbers is not only beneficial to wildlife but can help farmers be profitable
- new native breed cattle grazing the slopes - descended from ancient aurochs, these can play important role in creating space in the landscape for seeds to grow through trampling vegetation and grazing
- grazing animals play an important role in functioning ecosystems - browsing of trees and shrubs, breaks off branches and twigs, encourages new shoots
- horns debark trees and dung fertilises land, provides habitat for many types of dung beetle and other invertebrates
17
Q
Rewilding transition - in 50 years?
A
- full of life (including people), colourful, vibrant and echoing with bird song
- complexity and diversity is vital for strong, resilient, healthy ecosystems
- people, birds, insects, fish, domesticated animals, wild grazers and predators all integrated and interacting among woodlands, wetlands and grasslands
18
Q
Where is habitat loss happening?
A
- deforestation = highest in tropics
- related to practices established during colonialism
- some tropical forests will likely experience ‘tipping point’ after which point they revert to grasslands
- just 20-25% loss needed to this point
19
Q
Where is habitat loss happening?
Grasslands
A
- used to occupy 30-40% of world’s land area
- suitability for agriculture has led to destruction of many natural grasslands
- e.g. 97% loss of tall prairie in USA
- Difficult to estimate loss in many parts of the world
20
Q
Where is habitat loss happening?
Coral Reefs
A
- extremely biodiverse
- provide food/resources for <500 million people
- global economic value of $375 billion a year
- experiencing massive decline
- 25% already damaged beyond repair
- 75% are at immediate risk
- 90% projected to be in danger of being lost by 2030
- main risk = coral bleaching, due to climate breakdown: overheating leads to loss of symbiotic algae
- overfishing, carless tourism and pollution also contribute to loss
21
Q
Where is habitat loss happening?
Wetlands
A
- 53.5% global loss
- loss has slowed (esp Europe and N. America) under 1971 Ramsar Convention on Wetlands of International Importance
- Rates of loss still high in Asia and are not well measured in the tropics
22
Q
Where is habitat loss happening?
Freshwater
A
main issues: dams and flow regulation prevent access, pollution degrades habitats
23
Q
Land Sharing vs Land Sparing
A
- land can be used at different intensities
- better to use larger portion of land at lower intensity OR smaller piece of land at higher intensity, sparing some from development
24
Q
What is land sharing?
A
- integrate patches of natural habitat into landscapes that are characterised by small-scale farms with low-intensity land-use practices such as selective logging, organic farming, and low-intensity grazing
- also called wildlife-friendly farming
- strategies have gained popularity as an alternative to wasteful and environmentally destructive practices of large-scale commercial farming
- practices are already common in many developing countries where landscapes are dominated by smallholder farms and traditional agriculture
25
What is land sparing?
- set aside large areas of land as national parks and other protected areas that are separated from potentially damaging human activities like agriculture
- to feed growing human population, those who favour land sparing argue, we should intensify production and increase yields in current agricultural lands rather than expanding food production systems at the expense of natural habitat
- strategies are more consistent with "classical" conservation practices, which focused on setting aside large, well-preserved natural areas
26
Example of land sharing vs land sparing in agriculture
- conventional farming - large yields of monoculture crops, managed with heavy machinery, synthetic fertilisers + pesticides
- could spare land for conservation
- OR; organic farming - low-input, small-scale, diversified farms. Certified organic farming prohibits most synthetic inputs, while allowing organic fertilisers and pesticides
- Sustainably intensified farming - incorporates agroforestry, conservation agriculture, and biological pest control - produce low-input, resource-conserving agroecosystems
- Diversified farming - integrates several crops and/or animals in production system to promote agrobiodiversity, ecosystem services, and reduced need for external inputs
- Agroecological farming - emphasises integration of farms into surrounding landscape that conserves and manages biodiversity to support crop production, biological pest control, nutrient cycling and pollination
- Sustainable farming options do increase biodiversity
27
Are sustainable farming methods better if they use more land (so remove natural habitat)?
Compared two approaches in Ghana and Northern India found:
- more species -vely affected by agriculture than benefited from it
- land sparing = more promising strategy for minimising negative impacts of food production
Most species = highly adapted to niche - land sharing causes fragmentation and degradation - damages these niches
28
Land sharing AND Land sparing
- oversimplified
- figuring out how land sharing and sparing can contribute to conservation is both a challenge and opportunity for the next generation of practitioners
29
Land sharing AND Land sparing
Intensive agriculture vs lower-intensity agriculture
- pollution, habitat degradation often results
- ecological benefits (ecosystem services) of lower-intensity agriculture
- needs to be economically viable
- mechanisms for land sparing need to exist
- high yields with minimal impacts on nature will always be best
30
What is the main driver of biodiversity loss?
Habitat loss
