A species that has a disproportionate effect on the environment relative to its biomassMay structure ecosystems, determine the types and numbers of other species in a communityExamples? Predators can greatly effect prey behavior
(RED)What is a trophic cascade?
Occur when predators reduce the abundance of their prey, thereby releasing the next lower trophic level from predation
“What if the sea otters disappear?”
Greatly simplified food web…
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Plan and Treat and Multiple ScalesBuild resistance to wildfire Promote resilience to insect outbreakConserve Old-growth structureSustain local communitiesCreate and maintain management options
What are some dry forest restoration principles and their effects?
Reduce surface fuels -> Reduces potential flame lengthIncrease height to live crown -> Requires longer flame length to begin torchingDecrease crown density -> makes tree-to-tree crown (fire less probable)Keep big trees of resistant species -> Less mortality for same fire intensity
What is Clump distribution?
A major premise used in dry forest restoration
What are the most important strategic foci when deciding how to restore a dry forest area?
Clump size and distributionTree type choiceDecide whether or not to keep old treesHow to thinIsolate certain species?Preserve wildlife habitat?
Where does the cluster method work well (dry forest restoration)
Even aged stands with few old treeshigh graded stands with some old treesPlantations: PCT
Where are cluster methods not useful? (dry forest restoration)
Stands with major tree health issuesStands of where most of desired density is comprised of old trees
What are the three elements of biodiversity?
(RED)How relevant are biodiversity elements (Structure, Composition, Function) as restoration goals?
STRUCTURE:Variables are: Easy to measure Static (don’t change quickly)A common restoration criterion Focus on mean values and, increasingly, range of variationMight reflect particular site differences Ignores mechanisms that maintain structureCOMPOSITION:Variables are: Somewhat easy to measure (need ID skills) Fairly static (don’t change quickly)A common restoration criterionIgnores mechanisms that maintain compositionFUNCTION:Variables can be: Difficult to measure (e.g., CO2 flux) Dynamic – fluctuate spatially and temporallyNeed to choose the right variable!Requires strong understanding of ecosystem
Why is Function unique in comparison to Structure and Composition? (Biodiversity?
More generic than structure or composition E.g., same process can occur with different suites of species More relevant in light of climate change?Often assumes that structure and composition will develop once processes are ‘fixed’ E.g.
, estuarine restoratio
What would define a structural approach (biodiversity) to removing trees in a project?
Decide on desired forest structure (e.g., using reference data)Compare extant and desired structures to develop thinning prescription: How many trees to cut Which sizes of trees to cutModel how ecosystem process (fire behavior) responds to treatment
What would define a compositional approach (biodiversity) to removing trees in a project?
Favor some species over others E.g., Retain fire-tolerant species, remove fire-sensitive speciesNot a primary focus in SW: Forest contains few tree species Tree species present haven’t changed greatlyInvasive species
What would define a functional approach (biodiversity) to removing trees in a project?
Decide on desired fire behavior Model fire behavior under various stand management alternatives: How many trees to cut Which sizes of trees to cutChoose simplest alternative that achieves desired fire behaviorMeasure resulting forest structure
(RED)What is a keystone species?
A species that if removed will greatly alter the environment.It has a disproportionate effect on the environment relative to its biomass
(RED)What is a keystone process?
A process necessary to the balance of an environment.
Removal or alteration will guarantee a shift in the environment.
(RED)How does fire work as a keystone process?
Rationale:Forests were maintained in an open state by fireFire is missing now, so let’s put it back
(RED)What are reference dynamics?
Example: fire frequency
Are approaches to biodiversity exclusive?
No they are interchanging and usable in coexistence
(RED)How do the scales of biodiversity matter in restoration?
GENETIC:How much genetic variation do you want in planting stock?Horticulture: littleRestoration: lotsClonal plants: very little genetic variationAdaptation to sitePOPULATION / SPECIESFor a given species:Where to plant it? Clustered? Evenly distributed?How many to plant?When to plant it? All same age, or in cohorts?COMMUNITY / ECOSYSTEMSWhich species to plant together?Relation between species and environmental conditions E.g., wet habitatsInteractions – pollinators, etc.Scale that receives most attention during restorationLANDSCAPERelation of restored areas to matrix Energy and nutrient flows Distribution of patchesEdgesConnectivity
How / why do disturbances matter for restoration?
What is a disturbance?
A relatively discrete event in time that disrupts ecosystem, community, or population structure and changes the resource, substrate availability, or physical environment
(RED)Examples of disturbances?AbioticBioticAnthropogenic
Why do disturbances differ?
Ecological legaciesHistorical contingencyResource availabilityFrequencyPatch sizeSpecificityPattern and process
What is an ecological legacy? (Disturbances)
the living organisms, dead organic matter, and the physical structures … that remain after disturbance
What is historical contingency (Disturbances)?
Is a disturbance within the range of variation of historical disturbances?
Define resource availability (Disturbances)
More productive sites have more resources We can alter productivity
What is frequency (disturbances)?
Depending on the ecosystem, increases or decreases in frequency can cause problems
How does patch size play into disturbances?
Large patch Regeneration successionSmall patch(es) Patch dynamics Little change in compositionHeterogeneity of disturbance effects increases species diversity
What is specificity (disturbances)?
Who is affected?SpeciesAgeSizeHealth
What are the three themes of disturbances and which disturbances fall into each category?
Initial conditions:Ecological legaciesHistorical contingencyProductivity:Resource availabilityFrequencyOngoing dynamics:Patch sizeSpecificityPattern and process
How do disturbances apply to restoration?
Restoration often (always?) involves intentional disturbancesAppropriate’ disturbances depend on: ecosystem restoration goals
(RED)How can disturbance ecology inform restoration projects?
INITIAL CONDITIONS:Are site physical conditions appropriate relative to restoration goals?Are invasive species present?Do desired species need to be planted?How similar is disturbance to historic ones in this ecosystem?PRODUCTIVITY:Are resource levels appropriate?More productive sites often have more plant growth – especially by ‘weedy’ species – and faster growth ratesSome species are disturbance-dependentONGOING DYNAMICS:Disturbance characteristics affect community composition and structureHow often is disturbance required?Do disturbances target particular species? Eg, selective herbicide use Eg, fires to kill fire-sensitive species
What are the three categories of disturbance resistance?
Stable: able to return to starting valueResistant: changed little by disturbanceResilient: easily altered but rapidly returns to starting value
(RED)Brainstorm examples of ecosystems that are stable in spite of disturbances(RED)
Background’ levels of bark beetlesDrought in prairiesFire in fire-adapted systemsTides in intertidal zones
What type of disturbance is most likely to cause unstable ecosystem states?
Those not found in historical contingencyIs a disturbance within the range of variation of historical disturbances?
What is classical succession (ecosystem dynamics)?
Steady, directional change to a single equilibrium endpoint Goal = climax communityBased largely on species traits Competitive ability Stature Seed dispersalDeterministic – easy to model High predictabilityImplies that we just need to reverse the degradation Appropriate for minimally degraded sites Inappropriate for highly disturbed sites?
What are the three different views of ecosystem dynamics?
Classical successionState and transitionPersistent non-equilibrium
Define state and transition (ecosystem dynamics)
Some ecosystems change rapidly: Crash of fishery stocks Woody plant invasion of grasslandsLittle change until a threshold is crossedPossible to have multiple equilibriums
What are the implications for restoration of state and transition ecosystem dynamics?(RED)
‘Fits’ some systems well (e.g., rangelands)Implies more complex management than required by classical succession Moderate predictabilityNeed to understand thresholdsInitial conditions importantManagement may require different actions than caused original transition
How would you restore shrubland to grassland?(RED)
What is Persistent non-equilibrium (ecosystem dynamics)?
Assumes external factors are more important than in other views: Stochasticity (random events) Past history (legacies)Conceptual idea; difficult to ‘prove’ Difficult to distinguish from multiple equilibrium statesLow predictabilityRelevant for urban settings?
What is meant by Manipulating Dynamics (ecosystem dynamics)?
Can achieve similar results by different activities at different spatial and temporal scalesExample: recovery of riparian vegetation in Yellowstone Option 1: plant lots of trees and shrubs, protect from browse Option 2: reintroduce wolves; elk stay out of riparian areas and vegetation recovers
Disturbances initiate or direct subsequent ecosystem dynamicsModels of ecosystem dynamics:Summarize our ‘view of the world’Can guide restoration actionsTake time and effort to evaluate
Contrast Stresses and Disturbances
Stress. Eg: Desert organisms are adapted to seasonal and yearly fluctuations in precipitation.
Drought is not uncommon. Disturbance: Eg. Fire, grazing, or extreme drought can affect soil quality and vegetation for many years
What are some values of arid desert landscapes?
Plant and animal species not found anywhere elseEndangered speciesIndigenous food cropsPlant-derived drugs and other chemicals from drylandsFlood control, water purification, dust control, sustainable livestock use
What are threats to desert ecosystems?
GrazingAgricultureRoadsMilitary activityMiningRecreationPollution Changes to fire regimeInvasive speciesClimate change
What are some abiotic limitations to desert restoration?
Loss of topsoillate-successional species fail when planted into early successional soils. Moisture limitationsPulses of establishment with rain events Landscape scale factorsEg.
Restore low land with good soils, but if the slope above fails…
What are some biotic limitations to desert restoration?
Inoculation not possible for most species of microorganismsWeeds Arid systems tend to be open; disturbance adds new open spacesAnimals Herbivory, tramplingBiodiversity There are always more rare species than abundant species. Tradeoff between species that establish and stabilize the soil, but their longevity and competitive ability reduce return of native species.
What is the stress-gradient hypothesis? (desert restoration)
As abiotic conditions become more stressful, facilitation interactions become more commonFacilitation is where one species’ structure or function benefits another speciesEg. In areas of lower precipitation, seedlings rely more heavily on nurse plants.
What are the two main aspects of community assembly?
Filters and Priority effects
What are the filters of community assembly?
DISPERSALSpecies differ in dispersal abilityMethodDistanceBarriersENVIRONMENTSpecies differ in environmental tolerancesShadeNutrientsMoistureDISTURBANCE:Species differ in reaction to disturbances:TypeFrequencyDuration
What are the implications of the filters of community assembly?
Species selection is one of the most important decisions made during a restoration Only a subset of species can ‘pass through’ the filters at a given siteRestoration often: Overcomes dispersal limitation Alters environmental conditions Imposes select disturbances
What are Priority effects in community assembly?
Dominance generally by species that: Are already present at site: Extant vegetation Seed bankArrive first
Describe the colonization/competition trade off
Competition/colonization trade-offGood colonists = weaker competitorsPermits coexistence and species replacements
How can restoration control priority?
Site preparation to remove undesired species before plantingAdding species that would not colonize naturally or quicklyDo not need to assemble entire community at onceInterseedingCoordinate species introductions with stages in ecosystem development E.g., UBNA – shadeExpect some species to ‘phase out’ over time
What are the two main principles of restoration economics?
Economics deals with:IncentivesCosts and benefits
Responsible party vs No responsible party (who should pay for restoration)?
RESPONSIBLE PARTY: Feasible for some point sourcesThose who caused damage Eg, fines for Deepwater Horizon spillThose who will cause damage Eg, Mitigation bankingNO RESPONSIBLE PARTY:How are funds raised? Taxes General Specific products or activitiesVolunteers – money and timePrivate property owners
Name some economic valuation methods
Replacement cost: Cost of restoring a damaged systemReplacement cost multiplier: Cost of restoring an ecosystem plus additional funding for lost values during damage and uncertaintyValuing ecosystem goods and services: Evaluate economic benefits of restoring a given good or service using a tradeable substitute.
E.G, watershed for restoration vs. a water treatment plant to improve water qualityTravel cost methodHedonic price method
What are the three dimensions of commitment?
Affective: emotional attachment to, identification with, & involvement in volunteeringNormative: perceived obligation to volunteerContinuance (Calculative): perceived cost associated with quitting volunteering
Why do people commit?
People continue to volunteer over long periods of time because they are committed to the cause!Volunteer retention efforts can benefit from understanding what motivates commitmentContent of recruitment messages, Articulation of mission statements, Provision & organization of volunteering opportunities & settings
What are the 6 dimensions of motivations to volunteer?
Ego is an important predictor of initial participation—recruitment Social interactions are important for particular organizationsCommunity is a strong predictor of commitment—enduring involvement—retention Social factors are more significant predictors of participation & commitment to eco-restoration volunteerism Ecological motivations appear to moderate the effects of social interactions & community, but rarely so?