Managing endangered species paradigms
Forces that drive pop declines aren’t necessarily the same that drive to extinction. Manage for both.
PVA
POPULATION VIABILITY ANALYSIS = use of data/models to estimate persistence over time
E.g. northern spotted owl, modelling showed higher probability of decline with logging
COSEWIC
COM ON STATUS OF ENDANG WILDLIFE IN CANADA
Assessment:
Failure in protecting endangered species
Proposed oversight committee to coordinate planing/action between COSEWIC/SARA & provincial mgmt, monitor, etc
Large carnivores
Threats
Vulnerabilities
Umbrella species
Trophic downgrading
Loss of upper trophic consumers changes community structure & ecosystem function
E.g. wolves > deer > forest underbrush
Large carnivore conservation measures
Harvest managment
Yield = # individuals produced by population (overall growth, not growth rate)
MSY
Fixed-quota vs fixed-effort harvest
MSY
Maximum Sustainable Yield = largest yield taken indefinitely
Harvest management systems
Fixed-quota harvest
Fixed-effort harvest
GRAPHS:
Harvest management tactics
Restoration
RESTORATION = act of returning degraded to former condition
ECOLOGICAL RESTORATION = PRACTICE of restoring degraded ecological system
ACTIVE / PASSIVE = manipulation or not
RESTORATION ECOLOGY = process of developing THEORY to guide
- includes niche theory, pop dynamics, energy flow, community structure, etc
Paths to restoration
Reference conditions
A/biotic conditions, goal
Pre-settlement or Pleistocene rewilding
Difficulties = data, modern acceptance, identify cause, monitor
Alt stable states
Novel ecosystems = diff ecological composition & function due to changing species & envt
Life tables
LIFE TABLE = tool to analyze age-specific vital rates (fecundity, mortality, survival, etc)
Static life table = snapshot
Cohort life table = follow group, fecundity + mortality
Net reproductive rate = sum of survival * fecundity (lx * mx)
R > 1 pop inc
Fecundity
mx = # of female live births per female per unit time
Matrix population model
= bookkeeping of birth/survival using transition probabilities and matrix algebra
Leslie matrices = age-structured model of pop growth
Life history strategies
LIFE HISTORY = set of adaptations that influence survival and fecundity
K-selected = large, slow mature, low fecundity, high survival (competitive at K)
r-selected = small, opposite (maximize pop growth rate, r)
Survivorship curves
Type 1 (backwards r) = humans Type 2 (\) = many birds Type 3 (slide) = fish
Population regulation & limitation
POP REGULATION = process of returning to K
- density-dependent factors (competition, territoriality, disease)
POP LIMITATION = … determining K
- density in/dependent limiting factors (severe weather)
Density-dependent pop growth
- Growth rate declines as pop increase
Population growth models
GEOMETRIC growth = discrete steps
- lambda = per capita growth rate from N1 to N2 (>1 inc)
EXPONENTIAL = J curve
LOGISTIC = S curve
THETA-LOGISTIC = backwards r
- rate slows at higher density
Intrinsic rate of growth
rmax = max rate of inc in exponential growth (optimal conditions, constrained by phsyiology)
Don’t want harvest to exceed rmax in fixed-effort harvest approach
Estimating abundance