Transcript 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