The Present LECTURE 2

The Great acceleration

After WW2 Many things increased

• population

• economy

• scale of farming

• transport

• communication

Reasons for this

1. Restructuring the global economy around principle of growth

2. adoption and further dev of wartime technological innovation

3. strategic R+ D partnerships across governement, industry and achademia

Effects of the population tripling

1. >50% of useable land for food production

2. 25% of all available net primary production

3. Responable for global N fixation

4. Increased atmospheric CO2 to its highest level for at least 14My

Effects of threats→ Main threats

1. Habitat loss (the worst)

   • coral reefs

2. Overharvesting

   • 88% of fish stock overharvested

3. Invasive species

   • e.g insects

Effects on threats→ New threats

1. Climate change

   • 1.1 degrees above pre industrial

2. ocean acidification

   • >30% increase since 1800

   • coral reef cannot built skeletons

But less important than longer-established threats

Interactions of threats e.g roads

1. Habitat fragmentation

2. Direct mortality

3. Invasive species corridors

4. Spread of fire

5. Reduce habitat quaility around the edges (poolution, microclimate change)

6. Catalyse human settlement

5 main signals of these impacts on biodiversity

1. Increased rats of extinction

2. Variation in levels of threat

3. More general reductions in population sizes

4. Widespread disruption of ecological processes

5. Changes in community composition

1. Increased rats of extinction

• incresing numbers of specires threatened with extinction

2. Variation in levels of threat

• Taonomically

  • e.g amphibians hard hit

• Body size

  • larger bodied and plants impacted

• By realm

  • Freshwater species in greatest decline

• Geographically

  • highest in SE Asia (dense, fast growing populations and strong economic growth

  • Australia→ marked suscpetibility to invasives

3. More general reductions in population sizes

• General reductions in vertebrates and invertebrates

• 75% loss of vertebrates

HOWEVER: there is always up and down

• but declines observed too great to be explained by natural fluctations of initially abundance populations

4. Widespread disruption of ecological processes

• very many of which vary with species’ abundance

5. Changes in community composition

• increases in abundance of wide-ranging winner species

• declines in narrowly-distributed loser species

→ replacement explains why in some analyses site level species richness is maintained

• despite regional and global declines in richness

Is this a 6th mass extinction?

Might be close…

1. Extinction rates lie at the upper bound of interval-adjusted estimates of back ground rates

2. Predictions of impending extinction rates→ WAY larger than background rates

3. Magnitute of likely loss iwth be around 75% level seen in Big 5 events

   • (Assuming currently threatened species become extinct in the medium term)

Note: Impacts of mass extinctions on ecoystem functioning may take tens of thousand of years to unfold

Are we entering the Anthropocene?

• Human activities now rival the great forces of nature

-Some reject

-Some accept that this may be an event→ a time of unprecedented human transformatoin f the planet

Conservation responses over the past 75 years

1. Environmental laws and agreements

2. Conservation NGOs and IGOs

3. Protected area

4. Habitat management

5. Species management

1. Environmental laws and agreements

• e.g 1992 Convention on Biological Diversity

• restricting damaging activitires

• enabling conservation actions

2. Conservation NGOs and IGOs

Non and inter governmental organisation

• act on ground, raise public awareness, loby decision makers and help deliver international agreements

3. Proteected areas and OECMS

• other effective area-basedd Conservation Measures

• coverage increased recently

• came close to reaching CBD’s 2020 targets of 17% of the land and 10% of the seas

4. Habitat managment

• remove threats

  • invasive rats and goats

• maintain or restore ecological communities

  • impacted by the loss of natural distrubance agent such as flood and large herbivores

5. Spceis management

• target at particular threatened species

• making harvesting regimes more sustainable

  • e.g the MSC fish sustainable

• e.g Gorilla

Case study 1: Whales Facts

• resumed after WW2

• increased to smaller bodied spcies as stocks of biggests species depleted

• 1980s→ >3M whales has been caught since 1800

• recued population by 66-90%

Impacts of depletion: Ecological impacts

• reductions in tansport of N, Fe and other nutrients into euphotic zone

• reductions in whale falls

• desiment suspecion reduction

• shifts inp redation as whale specialised killer whales witch the smaller marine mammals

Changes in Management

1. International Whaling Commission

   • agrred to continue whaling

2. But in 1986 led to banning

3. Objectsions→ Japan, Iceland and Norway wontinued

Recovery?

• some populations have rebounded

  • southern rights, humpback, gry and blue

• Some have not

  • North Atlantic right whales

Case Study 2: Amazon Facts

• Collapse of rubber boom

• shift to commercial exploitation of animal skins

• >23M skins shipped out of Brazillian Amazon over the 20th century

Impacts

1. Species

   • Aquatic species severely hit as they were accessible by river

     • REALLY hit by first offtake

     • still low by the second

   • Terrestrial→ Less accessible from the river

     • Recovered after the first wave

     • (note: this is important in understanding which species are better suited for change→ important in conservation)

2. Habitat loss→ deforestation in 2nd half of the century

   • mineral, logging and infrastructure

   • MAINLY agriculture

   • AND in the remaining forests→ droughts and fires increased in freuqnecy

What has the clearance of land (deforestation) been driven by

• domestic demand of land

but also

• global markets:

  • Cattle ranching and soy production

  • driven by the rising pig production in China and he EU ban on pigswill

What happened between 2005-2012?

• Dramatic decline in deforestation

What caused the decline in deforestation from 2004?

1. Expansion of protected areas

2. Expansion of indinefous reserves

3. Increased enforcement of Forest Code

   • e.f 80% forest retention on private land

4. Buyers moratoia on soy and beef originaing on recently deforested land

5. Restrictied access to credit for landowner from blacklisted municipalities

6. Prospect of significant carbon payments

All implementated at the same time→ do not know which factor helped the most

What happened in 2012?

Pattern reversed→ governement relaxed enforcement of regulations

Highest level of deforestation since 2006

Why did this happen

1. Relaxed government

2. recession

3. falling currency

4. China-US trade wars

5. 2019 Jair Bolsonaro→

   • further appeasement of landowners

   • rise in illegal activitires in protected areas

   • reverse legal protection

6. Aug 2019 non-drought fires

Case Study 3: Mauritius

• deforestation continued through the 20th century

  • pine and tea

• Suffer from further invasive species

  • often used to control existing invasive mammals

    • e.g pigs dispersing strawberry guava

Early nature reserves

1. Catchment management

2. Viewing some invasives (deer, guava) as assets

   • Rate of invasive species introductions increased

Due to this poor management→ impact

1. 5% of the original forest reamined at the end of the century

2. 2% in good condition

3. 28 endemic plants now <10 individuals in the wild

BUT: work of Carl Jones in the 1970s

Stimulated growting internationla and national concern

Interventions to reverse the fortunes of many species

1. Creatin of Black River Gorges NP

   • largest national park in Maauritius

2. Intesnive restoration of vegetation

   • weeding, native planting and exclusion (by fencing and culling) of invasive mammals

3. Elimination of invasive mammals on islets

   • enable bird and reptile reintroductions

4. Intensive progagtion of critically endangered species

4. Intensive progagtion of critically endangered species

1. predator control

2. provision of supplementary food and nest sites

3. removal of eggs (for capture rearing)

   • so parents lay again (double-clutching)

4. Reintroductions of captive-bred birds:

   • Kestrels, pink pigeons and echo parakeets

   • now in their hundreds

Carl Jones 2008

“At the start of this work, the future of the endemic species of Mauritius seemed bleak, and many thought that few could be saved from extinction. Thirty years later the long -term conservation of all the island’s endemics is within our grasp.”