Ch9: Islands on Dry Lands/Invasive Species

Dr. Thomas Lovejoy

• decided to gain insight of habitat fragmentation on species of the rainforest in the Amazon

• cattleman were asked to clear forests and got stipends from the government in doing so

• they left some areas in tack, creating “islands”

• dr’ Lovejoy wanted to study these areas and protect them

  • found that some species will go extinct in the areas of islands, there is a biodiversity loss

    • thanks to his work, over 50% of the rainforest is protected

biome

• definition: a region or global land area that is characterized by its plants or animals that is specific to that areas ex: dessert, rainforests, etc

• difference between biome and anthrone is the way that humans are able to change the world to suite us

  • only species that are able to do this

• biomes give us knowledge on how the area once was, that animals are found three, etc

• anthromes are how humans have taken the area and transformed it

brazil biomes

• tropical rainforest makes of majority, ~60%

  • dense and heavy rainforest

• savannah’s ~20%

  • plains in a subtropical area

how land is used rn

• across the world, there are 50 million square miles of land that are ice free

• used as the baseline for human impacts

• humans have directly transformed 50% of this

  • crops, pastures, logging, minings, cities

• only 23 million square miles left

  • of that, 3/5 is the forests

    • this is not even pristine due to lines, pipelines, etc.

number of species in the amazon

• over 1300 bird species

  • probably even more due to different bird calls

  • collected by a ring and free technique

    • plots themselves recorded 1400 species of trees

refuge effects

as the forest decreases, the species will temporarily gain population, and then they will start to decrease

relaxation effects

• when you lose one species it starts to affect other species

• the vulnerable species start to loose numbers and get more prone to disease and other effects

• they are not able to survive these impacts anymore but would’ve been if they had the correct numbers

fragmentation

• dividing the region into smaller fragments

• in a fragmented region, the larger area of a habitat has been exposed to damaging outside influences like pollution

• sustainability of the ecosystem is now reduced because of the fragmentation

• species with large area and doesn’t have a lot of space to live

• diversity is self enforcing

  • high species diversity thrives because there is a lot of competition

    • leads to evolutionary instincts because they have to fight to survive more and get more specialized

  • when you remove these conditions, they become more vulnerable

• when plains disappeared in north America, species got his such as bisons and 50% of birds

biodiversity loss in African continent in the 21st century

• Millennium ecosystems assessment, inc

  • Assessed impacts on terrestrial biodiversity using biodiversity intactness index 

  • Predicts 21st century declines 2-3x greater than past 300 years 

  • Urgent need for better aligning biodiversity conservation and development priorities in, and across, regions

  • Human population increase correlates to biodiversity loss 

  • Have to look at much wider ranges, what happens to land, etc, much more accurate on whats going to happen instead of focusing on one specific animal

Army ants, eciton burchellii

• Carnivorous

• Always on the move 

• Build living bivouacs

• Can consume 30,000 prey/day

• Natives in areas have used ants for natural stitches

  • The ants bite the wound and then chop the head off

Hydrological cycles. Are we at the tipping point?

• Air and moisture comes up out of the air and travels for miles, then will come down in rain 

• When you defragment the land, at what point do you reach the tipping point that the clouds won’t happen anymore, which is the center of life for the rainforest

Time lapse land defragmentation in southern brazil

• Soil isn’t as rich, therefore not as good for crops 

• Sahara desert was one a green oasis in the center of civilization 

• It is thought that humans tipped the balance to make the sahara a desert

Biodiversity loss greatest since end-cretaceous extinction?

• E.O. wilson in 1980s calculated extinction rate was 10,000X greater than naturally occurring background 

  • Takes time for extinction, but incurs ‘extinction debt’

  • Regrowth always at play

  • Observational flaws

    • ex: conservation status, known is ~1% of known invertebrates

    • We don’t really observe everything that is going extinct

food web

• Start with a primary produces which is fed upon a primary consumer 

• Tertiary producer and consumer are at the top

• Global warming: On the move 

• Defragmentation 

• Ocean acidification 

• Invasive species 

  • U.S. has a lot of threats to invasive species 

• Ecological imbalance 

• These invasive species are going into an area that has never been there before

• It really thrives and takes over, outcompeting other species 

• Asian carp and killer frogs 

  • Killer frogs are in florida that is large and can kill cats and dogs

  • End up in an area without a natural predator 

  • These are killing off native species, destroying the ecosystem etc