Download Document

Final thoughts on the role of biota in global
environmental change.
Are species drivers or passengers?
They can be both…
most are passengers
a few are drivers….
the drivers have characteristics
capable of altering the biogeochemistry
of the system (and therefore move the
system outside the HRV)
Species as passengers: let the physical drivers
change the system:
Simple model of directional change
Resource alteration
Response
Community change
Community re-ordering
Physiological response
Time
Other nominees of ecosystem transformers
African C4 grasses in Chihauhuan desert
(grasslandification, like cheatgrass)
C4 grasses and N-fixers in Hawai’I
Eastern red cedars in plain states
Zebra mussels, New Zealand mud
snails….
Talus
Alpine
Subalpine
Montane
Savanna
Grassland
Grassland
Climate
atmospheric chemistry
fragmentation
disturbance history
biotic additions
Different ecosystems are experiencing different kinds and
different intensities of stressors
(replace word “stressors” with “drivers outside of their HRV”)
Ecosystem
Type
Alpine
Subalpine
forest
Montane
forest
Ponderosa
savanna
Prairie
climate
Global change issue
N deposition
fragmentation
HRV
biota
Ecosystem
Type
climate
Global change issue
N deposition
fragmentation
HRV
Alpine
X
X
Subalpine
forest
X
X
Montane
forest
X
X
x
?
Ponderosa
savanna
X
X
X
X
Prairie
X
X
X
X
(grasslands are therefore the most endangered ecosystem in
Colorado!!!???)
biota
X
Converting science to management
The science of information transfer
Relationship between science and
management
Sparse and infrequent
observations
MANAGEMENT
DECISIONS
Observational
errors
Incorrect
interpretation
Theoretical
misunderstanding
Oversimplified
models
Further refinement
of unimportant
details
Computer
models
CONTROVERSY
CONFUSION
Coincidental agreement
between theory and
observations
Unrealistic
assumptions
Crude diagnostic
tools
Further
misunderstanding
PUBLICATION
You’re fresh out of CU with a
degree in environmental biology,
and you’re hired to manage
Boulder Open Space.
What’s the first thing you do?
You’re fresh out of CU with a
degree in environmental biology,
and you’re hired to manage
Boulder Open Space.
What’s the first thing you do?
a) go drinking
b) hire lawyer
c) set some goals:
things you want, things you don’t want.
d) all of the above.
“Ecosystem management is management
driven by explicit goals…
made adaptable by monitoring and research
based on our best understanding of the
ecological interactions and processes
necessary to sustain ecosystem composition,
structure, and function.”
Ecological Society of America, 1996
UNNATURAL COMPONENTS OF OPEN SPACE:
1. Fire suppression and underutilization of fire has
changed species abundances.
2. Flood control has prevented riparian scouring.
3. Stream channel modification, irrigation ditches,
roads and trails have greatly altered hydrology.
4. Atmospheric nutrient inputs have increased.
5. Previous land abuses have left legacies.
6. A huge number of new species have been released.
The native-alien distinction is not important.
The real scientific issues are:
a) understanding impacts of novel organisms on
biological conservation and services of ecosystems.
b) understanding the impacts of novel environments
(systems exceeding HRV) on biotic diversity and
function.
c) the interaction of changes in both environmental
forcings and biotic composition.
B
Introductions,
extinctions
Biotic
Historical
composition Range of
variability
Abiotic drivers
A
Historical Range of Variability
Physical Conditions
A
Altered only by species changes
Altered
C
Biotic
composition
Historical
Altered only by
Physical/chemical
A
Historical
B
Altered
Environmental Conditions
B
New species change biogeochemical parameters
C
Altered
Adventive
ecosystem
B
Historical
Historical
Altered
Environmental Conditions
New biogeochemical parameters
Change biotic
Composition.
The adventive ecosystem (not an accepted term…
you heard it here first!)
“adventive” “ Not native to and not fully established
in a new habitat or environment.”
THE ADVENTIVE ECOSYSTEM
-----------Role of non-native species
biota
Natural System
Rock
Alpine
Subalpine
Montane
Savanna
Grasslands
Change in disturbance
Regimes (esp fire)
Changing climate and
changing atmospheric
chemistry
Adventive System
Rock
Alpine
Subalpine+homes
Montane+ranchettes+homes+
Savanna +ranchettes+homes+
Grasslands+agriculture +
ranchettes+suburban+urban
One axiom of ecosystem management:
“expect surprises”
(the interactions that form the basic behavior
of adventive ecosystems are being developed
as we speak…)
Perception
Vested
Interests
Policy
and
Mgmt.
Knowledge
Vested
Perception
Interests
Policy
and
Mgmt.
Knowledge