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 ChangeCommunity Change

ES 100: November 7ES 100: November 7thth, 2006, 2006

Millenium Ecosystem Assessment:Largest inventory of the health of Earth’s ecosystems

Experts and Review Process 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 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

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 non-native

species arrive?• Accidentally

seedsparasitesunintended cargo

• Deliberately• food• timber• pets• biocontrol

Data source: Eurostat. Source of figure: CNT, 2004

Data source: US Department of Transportation, 2004

Who are these invaders?

• Plants• Animals

• Microorganisms

What makes an invader successful?• r-strategists

• grow quickly• produce many offspring• short generation time

• good dispersion • generalists: highly adaptable to new conditions

• 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?

• human disturbance• early succession• climate similar to native habitat

• absence of predators or pathogens •wrong ones for the invader•no predators or pathogens at all - islands

What do invasive animals do?

• Change foodweb structure

• Hyperpredation

• drive out native competitors

and prey

Invasive Plant and Animal Mutualism

+

Management Options

Do nothing Understand life strategy

Vulnerabilities, limiting factor Predict where it will invade, rate of spread, during what

time periods…. Mathematical models! Remote sensing

ERADICATE! Other creative solutions????

Eradication

Physical control Chemical control Thermal control Biological control

PredatorVirusGrazing

www.dailynexus.com

Coalition Drops Black Rat Poison on Anacapa Island

by Rebecca Turek - Staff WriterThursday, December 6, 2001

Arundo: historic and future issues

Past, Present, Future Uses

Music Fiber (thatching) Lectin Biofuel?

The new trend……

ADAPTIVE MANAGEMENT:Treat management as an experiment

Learn from experience

How can we avoid invasive species and preserve biodiversity?

“Co-habitable” land use Land uses consistent with biota

Give up the green lawn! Organic/crop rotation based agriculture (but what is the cost?)

Habitat enhancement 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?

• What we see now wasn’t always here• communities do change

• Spatial scale is important• global vs. local change

• Time scale is important• long term change

• measured in 10’s of thousands of years or more

• short term change• measure on a decadal time scale

Short-Term Change

SuccessionTextbook 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

• Primary:• Community gets established on a new surface

• Lava flow• Meteor crater• Glacial moraine

• Secondary:• Recovery following disturbance

• 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• space, light, and nutrients are abundant• classic r-selected species (opportunists)

Primary succession• space and light are abundant• nutrients may not be• N-fixing plants are common

• convert atmospheric N2 into NH4+

How does succession happen?

Facilitation• early succession species alter conditions to favor

the growth of late succession species• 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?

• 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

• Community predestined by climate?

Mixed Beech-Maple Forest

Oak-Hickory

Willow shrub

Cattail marsh

Aquatic plants

Swamp

Oak woodland

Sumac-Pine

Broomsedge

Aster-Goldenrod

Annual weeds

Old field

Oak forest

Pine forest

Poplars

Dune grass

Sand dune

The Role of Randomness (aka Stochasticity)

2 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!