Wildlife Population Restoration - Session 7 - Lecture Questions Flashcards
Describe the three degrees of species-specific habitat heterogeneity:
- extreme cases
- partial isolation
- temporal fragmentation
Extreme cases: resource/veg patches can become isolated into island surrounded by very different and possibly unsuitable conditions.
Partial isolation: can affect population viability
- by lowering the # of animals per unit area of unsuitable/suitable environments
- by lowering dispersal and effective size of breeding pop.
Temporal fragmentation: refers to the degree to which a particular environment occupies a specific area through time
- E.g., old-field being perturbed, regrowing, and losing some of its original species
What 5 factors must be considered when considering species-specific habitat fragmentation?
- Absolute loss of habitat area
- Increased edge
- Increased distances for movement between patches
- Increased penetration of predators, competitors, and nest parasites
- Change in microclimate w/ changes in patch area/edge
Given the discussion on fragmentation, what is a common/important point to be aware of?
No general statements can be made about how conditions will influence predators that negatively impact target species
What four concepts should be considered for incorporating fragmentation issues into research/planning?
- Choice of spatial scale dramatically affects development of restoration plans
- Analyses are affected by several patch types/definitions
- Perimeter:area ratios should not be used as measures of fragmentation
- It’s better to measure different aspects of fragmentation seperately rather than combine them
Describe the four disturbance categories (w/ examples). How can these distrubances influence the abiotic/biotic environments?
Type I - major catastrophe (volcanoe, major fire, hurricane)
Type II - local distrubance (wind, ice storm, insects, disease)
Type III - chronic/systematic change over wide areas (predators, competition, forestry)
Type IV - minor environmental change (local fires, development)
What are some conclusions that can be made about disturbances and dynamics of resource patches?
- Response to disturbance is species-specific
- Generally, Type I greater impact than Type IV
- The closer disturbance mimics natural processes and better adapted species to adapt to changes
- The further human activities alter patch dynamics from natural processes, the greater then divide between the altered habitat and species’ ability to use it
What are some of the limitations around using indicator/umbrella species and WHR models to direct management in fragmented landscapes?
- One taxon usually fails to predict the response of other groups to environmental change
- WHR models estimate occurence w/o information, two important points:
- objectives must be clearly defined
- must verify/validate the model at each step of development/use
Describe the typical design of a reserve/corridor complex
- Corridor extends out from a central (“core”) part of the reserve, allows for movement of all species
- Core is surrounded by buffer layers
What controversial points should be noted about corridors in wildlife restoration?
- Corridors can increase extinction by promoting disease transmission
- Too little info is available for widespread use
- Corridors can enhance threats to species (wildfires, predation, domestics, poaching)
What are the four corridor designs?
- Continuous passageway
- Stepping stone concept
- Stepping stone w/ linkages between steps
- Low quality corridor relative to cores
What is the best corridor design?
There is no best corridor configuration, as it is a species-specific concept
What are some of the factors to be considered when determining if corridors are a viable option within a restoration project?
- Corridors will usually promote the movement of some individuals
- Poorly designed corridors will act as filters, that tend to allow the passage of generalists
- Specialists are unlikely to use poorly designed corridors
- Intra/interspecies interactions are important to consider in connectivity planning
- Species w/ physical limitations will need unique approaches
- All possible barries should be ID’d in the planning process
- Continous corridors are preferred
- Length/width are central to corridor utility
Exlpain the concepts of ‘buffers’
- Land-use zoning can influence activities surrounding the reserve
- Activities within the buffer can be designed to minimize impacts
- Buffers can become the corridor, connecting core areas
What are some of the adverse genetic affects associated with isolation?
- Fixation of deleterious alleles
- Increasing homozygosity
- decline in allelic diversity caused by genetic drift
- inbreeding depression (decreased fertility and fecundity)
- Founder effect from small initial populations
How does isolation influence extinction and colonization rates?
- Extinction rates exceeding colonization rate of native species
- Colonization rates exceed extinction for exotic species
- The smaller/more isolated the reserve, the great both processes occur
- If islands are sink habitats for native species, the fast this imbalance occurs
