Transcript Community Change

Announcements:
 No
Section this week
 Holiday Friday: no class
 Pick up Midterm exams tomorrow (Thursday 12-2
in TA office)
 HW passed out (posted soon): due in section next week
 Guest Lecture Monday: Come on time!!!
 Skim
Chapters 3, 18, 19 before class to get most out of
lecture!
Community Change
ES 100: November 7th, 2006
Millenium Ecosystem Assessment:
Largest inventory of the health of Earth’s ecosystems
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Experts and Review Process
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Prepared by 1360 experts from 95 countries
80-person independent board of review editors
Review comments from 850 experts and governments
Includes information from 33 sub-global assessments
Governance
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Called for by UN Secretary General in 2000
Authorized by governments through 4 conventions
Partnership of UN agencies, conventions, business, non-governmental
organizations with a multi-stakeholder board of directors
Significant and largely irreversible
changes to species diversity
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The distribution of species on
Earth is becoming more
homogenous
Humans have increased the
species extinction rate by as
much as 1,000 times over
background rates typical over
the planet’s history (medium
certainty)
10–30% of mammal, bird, and
amphibian species are currently
threatened with extinction
(medium to high certainty)
How do nonnative
species arrive?
• Accidentally
seeds
parasites
unintended cargo
Data source: Eurostat. Source of figure: CNT, 2004
• Deliberately
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food
timber
pets
biocontrol
Data source: US Department of Transportation, 2004
Who are these invaders?
• Plants
• Animals
• Microorganisms
What makes an invader successful?
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r-strategists
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good dispersion
generalists: highly adaptable to new conditions
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grow quickly
produce many offspring
short generation time
broad geographic range in native environment
broad diet
It has not coevolved with members of its new environment
What makes a community vulnerable to
invasion?
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human disturbance
early succession
climate similar to native habitat
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absence of predators or pathogens
•wrong ones for the invader
•no predators or pathogens at all - islands
What do invasive animals do?
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Change foodweb structure
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Hyperpredation
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drive out native competitors
and prey
Invasive Plant and Animal Mutualism
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Management Options
Do nothing
 Understand life strategy
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Vulnerabilities, limiting factor
Predict where it will invade, rate of spread, during what
time periods….
Mathematical models!
 Remote sensing
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ERADICATE!
 Other creative solutions????
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Eradication
 Physical
control
 Chemical control
 Thermal control
 Biological control
 Predator
 Virus
 Grazing
www.dailynexus.com
Coalition Drops Black Rat Poison
on Anacapa Island
- Staff Writer
Thursday, December 6, 2001
by Rebecca Turek
Arundo: historic and future issues
Past, Present, Future
 Uses
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Music
 Fiber (thatching)
 Lectin
 Biofuel?
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The new trend……
ADAPTIVE MANAGEMENT:
Treat management as an experiment
Learn from experience
How can we avoid invasive species
and preserve biodiversity?
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“Co-habitable” land use
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Land uses consistent with biota
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Habitat enhancement
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Give up the green lawn!
Organic/crop rotation based agriculture (but what is the cost?)
Variation of landscape
Restore disturbance regimes
Re-introduction
Laws and Regulations
Questions to Ponder:
 How
long do you have to inhabit an area to be a
native?
 What point in time should we restore to?
 Is fighting invasives a losing battle? What are the
costs of doing nothing?
 Which species would you say is most invasive?
How do communities change?
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What we see now wasn’t always here
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Spatial scale is important
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communities do change
global vs. local change
Time scale is important
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long term change
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measured in 10’s of thousands
of years or more
short term change
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measure on a decadal time scale
Short-Term Change
Succession
Textbook definition:
“a change in species that occupy a given area, with some
species invading and becoming more numerous while
others decline in population and disappear”
Can be thought of as the replacement of one
community by another
Primary vs. Secondary Succession
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Primary:
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Community gets established on a new surface
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Lava flow
Meteor crater
Glacial moraine
Secondary:
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Recovery following disturbance
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Fire
Flood
Post-agriculture
Succession in Sycamore Canyon?
Succession in Sycamore Canyon?
Succession in Sycamore Canyon?
Succession in Sycamore Canyon?
Who Wins?
Early vs. Late Succession Species
Early
• shade intolerant
• nutrient demanding
• short-lived
• poor competitors
Late
• shade tolerant
• adapted to lower nutrient
conditions
• long-lived
• good competitors
Who wins in the beginning?
Secondary succession
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space, light, and nutrients are abundant
classic r-selected species (opportunists)
Primary succession
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space and light are abundant
nutrients may not be
N-fixing plants are common
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convert atmospheric N2 into NH4+
How does succession happen?
Facilitation
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early succession species alter conditions to favor
the growth of late succession species
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N-fixers make soil richer
dune grass stabilizes sand
Acceleration
•late
succession species alter conditions to favor their own
growth and prevent the growth of early succession species
•some
plants produce toxic litter
Is Rate of Community Change
Increasing?
 Depends
on time scale but consider:
More
human-induced disturbance
Global
affects (changing climate, sea levels,
soil temperature/structure)
Invasive
Species!!!
Predestined Communities?
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A community is a group of living organisms
that occupy a certain area and interact with one
another.
Clement’s climax community theory
Classic Succession
Clements’ idea of “climax community”
• eventually, a given system reaches a predictable
steady-state
• independent of the early succession community
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Community predestined by climate?
Mixed Beech-Maple Forest
Oak-Hickory
Oak woodland
Oak forest
Willow shrub
Sumac-Pine
Pine forest
Cattail marsh
Broomsedge
Poplars
Aquatic plants
Aster-Goldenrod
Dune grass
Annual weeds
Swamp
Old field
Sand dune
The Role of Randomness
(aka Stochasticity)
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species are equally suited to be next “successors”
 Outcome
is CHANCE (dispersal, weather, ect.)
Why Is Succession Important?
 Understanding
‘natural’ disturbance recovery can
aid human’s restoration efforts.
 Biotic
and Abiotic processes are important
 Management
plans must recognize that disturbance
is not intrinsically bad!
Announcements:
 No
Section this week
 Holiday Friday: no class
 Pick up Midterm exams tomorrow (Thursday)
 HW passed out: due in section next week
 Guest Lecture Monday: Come on time!!!
 Skim
Chapters 3, 18, 19 before class to get most out of
lecture!