EGS Pippin 7 Degradation Flashcards
Degradation def:
The loss of biological or economic productivity as a result of poor land management
What generally causes degradation:
Patterns emerging from human activity resulting in:
* soil erosion,
* deteriorating physical, chemical, biological properties of soil,
* & long term loss or negative change in vegetation cover.
Other causes of Degradation P1/
(1)
(2)
(3)
(4)
(5)
(1) Tourism
(2) Agriculture
(3) Mining
(4) Energy
(5) Urban Development
Other causes of Degradation P2/
(1) Tourism:
→
→
→
→
(2) Agriculture:
→
→
→
→
(1) Tourism:
→ littering
→ Paths/going off road, etc
→ Camp sites
→ Breaking things off
(2) Agriculture:
→ Land clearance/deforestation
→ Pesticides/fertiliser run off
→ Cows - methane emissions
→ Desertification
Other causes of Degradation P3/
(3) Mining:
→
→
→
→
(4) Energy:
→
→
→
→
→
(5) Urban Development:
→
(3) Mining:
→ Open pan, destroying veg. cover
→ Chemical pollution
→ Ecological dead zones
→ Water pollution
(4) Energy:
→ Dams - flooding, erosion, alters rivers
→ Coal mining
→ Oil rigs, fracking, etc. - massive ecological degradation & pollution
→ Solar farms - cover/block veg.
→ Wind farms - impact birds/bats
(5) Urban Development:
→ Habitat Loss
How does Degradation Manifest?
(1)
(2)
(3)
(1) Soil Degradation
(2) Bush encroachment
(3) Spread of Alien Invasive plant species
Bush Encroachment P1/9
What is Bush Encroachment?
The proliferation or increase in woody plant species density, at the expense of grasses and forbs
Bush Encroachment P2/9
Process:
- Entails some (), often (), which () an () of ().
- Which then invade () & () created through e.g. ()
- These (), often () () species are dispersed by (), and () & () easily.
- Lack of () through (/) + Lack of () () = () reach ().
- () shade out () & (), serve as () & () sites = ()
(1) Entails some disturbance, often grazing, which favours an influx of weedy trees
(2) Which then invade open areas & gaps created through e.g. over-grazing
(3) These opportunistic, often weedy tree species are dispersed by large herbivores, and germinate & establish easily
(4) Lack of Fire through management that suppresses fire/ fire suppression w. shift in plant community composition + Lack of Browsing animals (most livestock graze) = Trees reach maturity.
(5) Trees shade out grasses & forbs, serve as bird perch & seed dispersal sites = Dense Bush
Bush Encroachment P3/9
@ Local Scale:
- () of (), e.g. around (), (), or (), creates () as () dies back.
- () or () reduces the () of some species, allowing others to (), and creates ().
- Higher () around () due to the collection of () & () favours some species & influences () between () in the plant community
- () & () , reduces (), favouring a (), and ().
- Trampling of sacrifice zone, e.g. around water points, food troughs or kraals, creates gaps as original veg. cover dies back.
- Selective browsing or grazing reduces the competitive vigour of some species, allowing others to expand, and creates gaps
- Higher soil nutrients around water points due to the collection of animal dung & urine favours some species & influences competitive dynamics between species in the plant community.
- Gaps in & general reduced veg. cover reduces fire frequency, favouring a biome switch, and Bush Encroachment.
Bush Encroachment P4/9
Graph:
- Depicts the () & () involved in bush encroachment.
- They are given in () from a (A) zone, but could also be () in ().
- Here a () & () zone @ a () becomes a (A) zone.
- Just outside the A zone, grazing is still () & () & there is still (), and this becomes an (B) zone.
- In the (B) zone, () is reduced, () is suppressed & () species come in & are () by the () found there.
- () that removes the () species, sees the () proliferate
- The next zone is a (C) zone, where () & () & () are not as (), but still some () & associated ().
- The (D) zone is the () from the (A) zone & still has () intact.
- Depicts the phases & processes involved in bush encroachment.
- They are given in distances away from a Sacrifice zone, but could also be phases in time.
- Here a heavily grazed & trampled zone @ a focal point becomes a Sacrifice zone.
- Just outside the Sacrifice zone, grazing is still heavy & intense, & there is still trampling, and this becomes an Encroachment zone.
- In the Encroachment zone, biomass is reduced, fire is supressed & weedy pioneer woody species come in & are favoured by the higher nutrients found there.
- Selective grazing that removes the grass species, sees the unpalatable species proliferate.
- The next zone is a Mixed zone, where grazing & trampling & nutrient enrichment are not as intense, but still some degradation & associated encroachment.
- The Non-encroached zone is the furthest from the Sacrifice Zone & still has original veg. type intact.
Piosphere definition:
The zone of influence of grazing on vegetation & soil around a point of intense use, usually a waterpoint or a feeding trough
- lend themselves to gradient analysis
Bush Encroachment P5/9
Causes of Bush Encroachment in Savannas:
(1)
(2)
(3)
(4)
(5)
(1) Fire suppression in early 20th C. - historically suppressed bc. ppl thought it bad 4 veld.
(2) Intense livestock grazing - stock no. too high to be sustainable → shifting community dynamics
(3) Indirect fire suppression - w. reduced biomass (heavy grazing) → less to burn/carry → natural fires reduced
(4) Compounded by century of little/no browsing - long period of unrestrained hunting → reduced browsing animals in system → bushy plants & trees flourish
(5) Ever increasing CO2 - Higher atmospheric CO2 favours woody species (C3 photosynthetic pathway) → competitive adv.
Bush Encroachment P6/9
How to control Bush Encroachment?
(1)
(2)
(3)
(1) Mechanical
(2) Chemical
(3) Biological
Bush Encroachment P7/9
Bush encroachment control: Mechanical
* Entails:
* Pros
* Cons
- Entails: Cut & Clear
- Pros: Effective & generates Firewood
- Cons: very Labour Intensive & Disruptive (steep slopes → erosion)
Bush Encroachment P8/9
Bush Encroachment control:
Chemical
- Entails:
- Pros:
- Cons:
- Entails: Aerial spray of woody-specific Herbicides
- Pros: Effective, generates Firewood & Jobs
- Cons: often unintended Negative impact on Non-targeted species
Bush Encroachment P9/9
Bush Encroachment control:
Biological
- Entails:
- Entails: use Browsers (goats) & Fire (every 3-4 years in wet areas & 10-15 years in drier areas)
Alien Invasion P1/3
-
Stages:
(1)
(2)
(3)
(4) -
Factors:
→ Stage 1:
→ Stage 2:
→ Stage 3:
→ Stage 4: -
Matters to consider & research qs:
→ Stage 1:
→ Stage 2:
→ Stage 3:
→ Stage 4:
Stages:
* (1) Introduction
* (2) Establishment
* (3) Spread
* (4) Impacts
Factors:
- Intro: Some vector (usually humans), intended or unintended
- Establishment: Life history, environmental tolerance
- Spread: Carrying capacity, interspecific competition
- Impacts: Economic, social, responses (research, control, eradication, restoration, management)
Matters to consider & research qs:
- Intro: What informs introductions, how might they be controlled? Try and be proactive
- Establishment: What factors contribute to establishment (timing, place)
- Spread: Rates of spread, patterns of spread, measures for monitoring
- Impacts: Establish sources, points of entry for future management. Are there positive impacts? What are the costs? What control, management or eradication, options exist? What are the implications of eradication?
Alien Invasion P2/3
Invasion Curve:
- Draw axes
- What is X axis
- What is Y axis?
- X axis is divided into 3: (A); (B); (C)
- What occurs in (A)
- What occurs in (B)
- What occurs in (C)
- Rank Eradiction efforts needed.
- Go to notes
- X axis = Time →
- Y axis = Area Infested ↑ & Control Costs ↑
- X axis divided into 3:
→ Lag Phase;
→ Exponential Growth;
→ Carrying Capacity - What occurs in Lag Phase:
→ Intro
→ then Detection - What occurs in Exponential Growth:
→ Land managers aware of problem &
→ then Public awareness begins - What occurs in Carrying Capacity:
→ No label - Rank Eradication efforts needed:
→ Lag Phase: Prevention/Eradication SIMPLE
→ Exponential Growth: @ Land Managers = FEASIBLE; @ Public awareness = UNLIKELY & Intense effort needed.
→ Carrying Capacity: Local control & management ONLY
Alien Invasion P3/3
What makes a GOOD Invader:
(1)
(2)
(3)
(4)
(5)
(6)
- Produce lots of seed with ease
- Have short generation times
- Water, wind or bird dispersal over large areas
- Seeds germinate earlier than indigenous species → competitive head start
- Plants grow faster & taller than indigenous species
- Lack natural pests & pathogens
What are the implications of Degradation
(1) Economic:
* P1:
* P2:
* P3:
* P4:
(2) Conflict:
* P1:
* P2:
* P3:
(1) Economic:
* Reduced stocking capacity in beef industry in Botswana (Bush encroachment)
* Reduction in wild flower exports (alien invasion protea)
* Health & associated economic impacts (reduced water availability)
* Food security (invaded water catchments)
(2) Conflict:
* Mental health issues (economic or livelihood issues)
* Anxiety w. reduced recreational potential (heavy alien invasion & no public access)
* Economic migration that can result in conflict as people move around in search of work.
How do we measure degradation?
(1)
(2)
(3)
(1) NDVI
(2) Millennium Ecosystem Assessment (MEA)
(3) Field Research
thorugh indicators??
What are indicators?
- “A variable hypothetically linked to the variable studied which cannot be directly observed”
- Some measure that simply communicates more complex phenomenon
- Indicators can be qualitative or quantitative.
Indicators of degradation:
(1)
(2)
(3)
(4)
(5)
(6)
(1) Reduction or Increase of Biomass
(2) Soil Depth (soil lost through erosion)
(3) Crop Yield
(4) Habitat Loss & Conversion
(5) Bush Encroachment & Invasive species
(6) Social surveys (asking people if they think their land is degraded)
