Conservation Bio exam 3

What are the factors driving all environmental problems (2 main ones, and a few others)

1. human population size

   1. growth is slowing, will likely peak at 10-11 billion in 2050-2100

2. resource use

   1. how many humans the Earth could indefinitely support depends on resource use

   2. resource use is currently increasing by 3% each year

      1. driven by decreasing poverty in some areas, and continued growth in wealthy countries

      2. 25% of Earth’s net primary productivity is used by humans (= amount of sun’s energy that is converted to plant biomass)

• globalization

  • has pros and cons - for conservation:

    • consumers buy products but can’t see the impact of those products in other countries

    • investors can’t see the impact of their investments in other countries

    • poor countries often have huge debts and sell access to resources to pay off this debt

• poverty

  • 1 billion people live on less than $1 per day

  • 2.7 billion people “““ less than $2 per day

  • people living in poverty often impact local resources

    • also see firsthand environmental impacts but lack the $, education, of free time to address them

  • conservationists / organizations must take needs of people in poverty into account when solving conservation problems

define habitat loss

= a habitat is converted into something entirely different

define habitat degradation and give an example

= the habitat is still there, but has been so impacted that many of the original species no longer live there

ex: severe overgrazing of a prairie, channelization of a river

what is the #1 reason behind species decline?

habitat loss

• species are 2-4x more likely to be endangered b/c of habitat loss than any other problem

describe oldest known examples of habitat loss

7,000 years ago agricultural expansion in the Mid East - used to be dry forests, now sand

describe how both grasslands and forests have been impacted by habitat loss / degradation

grasslands

• have the hihgest rates of habitat loss of any ecosystem

• mostly for row crops or grazing

forests

• severe loss and degradation in all forest types except Boreal Forests

• 25 countries have 0% of their original forests remaining

  • additional 29 countries have had loss of 90%+

  • forests are returning to some of these countries, but are very young

• habitat loss is improving in some areas, but declining in others

• forests are big players in global climate

  • release water into the air (atmosphere)

  • store carbon

describe how freshwater ecosystems (rivers/streams) have been impacted by habitat loss / degradation

rivers / streams

• damming has big impacts:

  • why do we have dams? : recreation, hydroelectric power, store drinking water, flood control, irrigation

  • problems created by dams

    • prevents upstream movement of organisms

    • flood large areas

    • disrupts natural flow patterns throughout the year - these flow patterns triggered reproduction in many river organisms

• channelization

  • = rivers are straightened, made deeper and narrower. side to side movement is limited by rock along sides and dikes pushing water to middle

  • done to allowing farming / urbanization up to river’s edge & barge traffic

  • from conservation standpoint:

    • river is simplified - all habitat is fast and deep

    • natural rivers have many shallow, slow areas, oxbows, old river channels, etc

• in US, less than 2% of rivers are unmodified

• loss of stnading water wetlands

  • mostly drained for agricuture

  • greater than 50% of wetlands gone in US, and it is worst in Midwest

    • about 60% gone in Europe

What causes Habitat Loss / Degradation (#1 cause, and others)

• #1 cause is agriculture - row crops, grazing, palm oil, aquaculture

• urbanization - 3% of Earth’s land is urbanized - for industry, residential, roads

• resource extraction - mining, timber harvesting, fishing (trawling)

• dams

• war

describe how agriculture has changed over time and the impacts

1. 1st ag settlements - 8,000-12,000 ybp, various locations around the world

   1. impact on habitat was severe but very localized

   2. impact grew as pop grew

2. Industrial Revolution - mid 1700s

   1. explosion in avaliable mechanized tools

   2. replaced human and livestock power w/ fossil fuel power

   3. dramatically increased amount of land worked in a day

   4. human pop growth exploded

3. Green Revolution - 1940s-1960s

   1. Iowa was at center of movement

   2. big improvements in mechanization, breeding of crops, pesticides, fertilizaers, and monocultures

4. Today

   1. crop lands make up about 13% of Earth’s land area - 98% of farmable land

   2. # is still growing (more land being farmed)

define habitat fragmentation

= breaking large blocks of habitat into small, isolated pieces

habitat loss usually leads to habitat _____________

fragmentation