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)

Physiological response

Community re-ordering

Community change

Res

po

nse

Time

Resource alteration

Physiological response

Community re-ordering

Community change

Res

po

nse

Time

Resource alteration

Species as passengers: let the physical drivers change the system:

Simple model of directional change

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….

TalusAlpine

SubalpineMontaneSavanna

Grassland

Climateatmospheric chemistryfragmentationdisturbance historybiotic additions

Different ecosystems are experiencing different kinds anddifferent intensities of stressors

Grassland

(replace word “stressors” with “drivers outside of their HRV”)

Ecosystem Global change issue

Type climate N deposition fragmentation HRV biota

Alpine

Subalpine forest

Montane forest

Ponderosa savanna

Prairie

Ecosystem Global change issue

Type climate N deposition fragmentation HRV biota

Alpine X X

Subalpine X X forest

Montane X X x ? forest

Ponderosa X X X X savanna

Prairie X X X X X

(grasslands are therefore the most endangered ecosystem in Colorado!!!???)

Converting science to management

The science of information transfer

Sparse and infrequent observations

PUBLICATION

Observationalerrors

Incorrectinterpretation

Theoreticalmisunderstanding

Oversimplifiedmodels CONTROVERSY

Further refinement of unimportantdetails

Computermodels

Unrealisticassumptions

Crude diagnostictools

CONFUSION Furthermisunderstanding

Coincidental agreementbetween theory and

observations

MANAGEMENTDECISIONS

Relationship between science and management

You’re fresh out of CU with adegree 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 adegree 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 environmentalforcings and biotic composition.

Historical Range of Variability Physical Conditions

HistoricalRange ofvariability

Bioticcomposition A

BIntroductions,extinctions

Abiotic drivers

Historical Altered Environmental Conditions

Altered

Historical

Bioticcomposition

A B

C

A Altered only by species changes

Altered only byPhysical/chemical

Historical Altered Environmental Conditions

Altered

HistoricalB

C

BAdventiveecosystem

New species change biogeochemical parameters

New biogeochem- ical parametersChange bioticComposition.

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

biota-------------Role of non-native species

Rock Alpine SubalpineMontaneSavanna

Grasslands

Rock Alpine

Subalpine+homesMontane+ranchettes+homes+Savanna +ranchettes+homes+

Grasslands+agriculture + ranchettes+suburban+urban

Adventive System

Natural SystemChanging climate andchanging atmosphericchemistry

Change in disturbanceRegimes (esp fire)

One axiom of ecosystem management:

“expect surprises”

(the interactions that form the basic behaviorof adventive ecosystems are being developed as we speak…)

Vested

Interests

Policy

and

Mgmt.

Perception Knowledge

Vested

Interests

Policy

and

Mgmt.

Perception Knowledge