Environmental Studies Exam 2

Ecological consequences of climate change: species shifts, extinction, trophic cascades from smaller organisms

Species Shift: Towards Higher Latitudes and Elevation

Extinction: 15-37% of all plants and animals are committed to extinction by 2050

Smaller Organisms: Cold Blooded Animals reach adulthood at a smaller size

Changes in disease and vectors due to climate change?

Increase in suitable habitat

Shorter Generation Time

Increase in disasters which damage water and sewage systems

Climate change Key impacts on agriculture?

Longer growing seasons but increased damage to crops in summer where heat is a constraint.

Changes in rainfall patterns

More frequent extreme events

Climate change in synergy with other environment problems?

Hurricane Katrina: Stronger storms (climate effect) + Loss of coastal wetlands

Habitat Fragmentation + Shifting Ranges (climate effect)

Coastal Groundwater depletion + Sealevel rise (climate effect)

GPP?

Gross primary productivity: rate at which plants capture solar energy

NPP?

Net primary productivity: rate of plant growth. NPP= GPP - plant respiration

How much energy is lost between trophic levels?

About 90% of energy is lost

Where is N2 found and how does it move?

In the atmosphere and plants can’t use it directly

Where is NH4 found and how does it move

Soil, plants can absorb it

NO3 where is it found and how is it moved

Soil———>Runoff and groundwater, plants can absorb it and pollutes water

Organic N where is it found and how does ti move?

Organisms and Dead Material, Protiens and DNA

Where is NO found and how does it move?

Atmosphere and its from burning fossil fuels, causes acid rain

Where is NH3 found and how does it move?

Industrially made through haber Bosch and used in fertilizer

What is N fixation?

Bacteria convert N2 gas into ammonium

What is nitrification?

bacteria convert NH4 into nitrate

What id denitrification?

Bacteria convert NO3 into N2 or N2O gas. Happens in low oxygen waterlogged soils, so wetlands are key sites for removing excess N

What are rhizobia for

Need a plant host and form nodules on legume roots. The key N fixers on land.

What are cyanobacteria for

Free-living and found everywhere. Key N fixers in water.

What are some humans changes to the N cycle and how they specifically cause different environmental problems and the forms of nitrogen associated with these problems

Fertilizer runoff in sewage systems. NO3 in surface water. Creates eutrophication which uses up O2 and a dead zones.

Burning fossil fuels. NO-HNO3 which creates acid rain and kills aquatic life.

Trophic bottom up?

The food supply controls the consumer above it

Trophic top down?

Contols the level below them

Trophic cascade

A predator suppresses its prey, which releases the next level down which trickles down the food web

Bioaccumulation?

Toxins build up inside one organisms over its lifetime (absorbs them faster than it releases)

Biomagnification?

Toxic concentration increases at each higher trophic level

Biodiversity and its importance to ecosystem function

Biodiversity supports function and resilient ecosystems through genetic diversity, evenness, number of species

Cardinale et al 3 sentences

Biodiversity increases the stability of ecosystems over time

The effect is non linear and saturating and the first losses do little, but changes accelerates as losses increases

Losing diversity across trophic levels affects ecosystems affects ecosystems more than losing diversity within a single level

Ecosystems functions vs services

Ecosystem functions - ecological processes that move energy, nutrients, and organic matter through an ecosystem.

Services: the benefits people get from functioning ecosystems.

EX) Microbes decomposing dead material → breaking down our wastes.

EX)Wetlands processing nutrients → purifying our water.

EX)Trees storing carbon → stabilizing the climate.

Human elephant conflict at Liwonde – sources of problem, possible solutions

Source of problem - Dense human population, no perimeter fence, entering of the park to fish which caused interactions with elephants

Strategies for reducing human–animal conflict

• Fences:

• Ranger patrols

• Growing bird’s eye chilis as a cash crop:

What is revenue sharing?

• Park entry fees and other tourism money are shared with communities around the park.

• This gives local people a reason to support conservation, where attitudes had been antagonistic.

Benefits and problems with translocation

Benefits - Less conflict at the source: Liwonde had no human or elephant conflict deaths the year after.

Restocks a poached-out park: Nkhotakota had dropped from about 1,500 to fewer than 100 elephants. New calves have since been born there, and tourism is growing.

Acts as a “human-assisted migration” in a country with no wildlife corridors.

Problems

• Risky for the animals: sedation, heat, and stress. Two elephants died.

• Very expensive and labor-intensive (helicopters, vets, cranes, trucks).

• Breaks up family groups. Moved elephants may wander out or try to return home.

What is CITES

The Convention on International Trade in Endangered Species of Wild Fauna and Flora.

Purpose: to make sure international wildlife trade doesn’t threaten species’ survival. It has 185 member countriesand covers more than 40,000 species.

Latitudes with the highest biodiversity

Low latitudes (the tropics). Panama and Costa Rica have more than 500 breeding bird species; the Arctic has 30–100.

Background extinction

the slow, normal, ongoing rate of extinction, roughly 10% of species per million years.

Mass extinction:

at least ~75% of species lost in a geologically short time (usually under ~2 million years), triggered by a catastrophe.

Why are predators particularly imperiled?

• Directly killed: people fear them and hunt them for fur and other products.

• Top of the food web:

  • Toxins biomagnify in them.

  • They are vulnerable to any change lower in the food web, and there are few of them to begin with (the 10% rule).

• Need large ranges, so they are vulnerable to human encroachment.

Biodiversity hotspots

Regions with many endemic species (found nowhere else) that are highly threatened.

riteria:

1. At least 1,500 endemic vascular plant species (more than 0.5% of the world’s total), AND

2. At least 70% of original habitat lost

22. IUCN Red List what is it and goals

• The international standard for tracking species’ conservation status, based on scientific data.

• Two goals:

  1. Document the species most in need of attention.

  2. Provide a global index of the state of biodiversity.

23. Island biogeography

• 
  

• Size: bigger islands have more species (more habitat, larger populations, fewer extinctions).

• Distance: islands closer to the mainland have more species (more colonists arrive).

• Fragmentation: fragments of habitat act like islands, and intact habitat is the “mainland” source. Small, isolated fragments lose species, which argues for large reserves and corridors.

Proximate causes of biodiversity loss: habitat distraction, habitat fragmentation, habitat degradationtion, invasive species, overexploitation

• Habitat destruction (less habitat): deforestation, plowing prairies, draining wetlands (half of U.S. wetlands are gone), burying streams (more than 2,000 miles buried by mountaintop-removal mining).

• Habitat fragmentation (habitat broken into patches): roads and highways. Consequences: roadkill, smaller populations, less gene flow, higher extinction risk.

• Habitat degradation (lower-quality habitat): acid rain killing forests, polluted runoff, trash, sediment pollution.

• Invasive species (non-native species that cause harm): kudzu, zebra mussel, Asian carp, purple loosestrife, nutria.

• Overexploitation: poaching (ivory, tiger parts, wild ginseng) and overharvest (overfishing, logging, overhunting).

Biodiversity and ecosystem function AND stability

See #13. On stability specifically:

• McGrady-Steed: diverse communities had less variable function.

• Tilman: diverse plots kept productivity through drought.

• Kennedy: diverse plots resisted invaders.

• Worm: diverse ocean regions rebounded better from stress.

·      Ocean acidification – what are the main kinds of organisms impacted?

Main organisms impacted: calcifiers (organisms that build calcium carbonate shells or skeletons):

·      Know findings of readings Nicolls et al, Fabry et al., & Cardinale et al

Nicholls & Cazenave (2010): Sea level is rising faster and faster because warming water expands and land ice melts, and human-caused sinking of coasts makes it worse, which puts low-lying deltas and small islands most at risk.

Fabry et al. (2008): The ocean is absorbing CO₂ and becoming more acidic, which makes it harder for shell-building animals like pteropods, plankton and shellfish larvae to build their shells, hitting cold polar waters first and likely reshaping marine food webs this century.

Cardinale et al. (2012): After 20 years of research, scientists agree that losing biodiversity makes ecosystems less productive and less stable, and the damage speeds up as more species are lost.