Sp and Landscape Conservation

1
Sp and Landscape Conservation

• Frequently when it comes time to save or manage a
  species, nations identify and protect critical
  habitat
• International treaties also tend to have a
  species-oriented approach (e.g. CITES)
• Conservation education tends to be
  species-oriented (e.g. pandas, wolves)

2
Sp and Landscape Conservation

• Additionally, much of the information in
  conservation biology is focused on the individual
  species
• Even when taking a larger view, it is still
  simply counting species (e.g. hotspots, high
  endemic areas)
• Consequently, we will try to better understand
  small population biology

3
Sp and Landscape Conservation

• Populations change pop(s) are dynamic and are
  governed by 4 factors
• Although the model of population change is
  relatively simple, identifying the process
  driving changes is not
• Some pop(s) are extremely consistent while others
  amaze us with their variation

4
Sp and Landscape Conservation

• Organisms themselves may experience a relatively
  narrow view of the world (a generation of
  rotifer) while others perceive similar conditions
  for many generations (e.g. humpback whales)

5
Sp and Landscape Conservation

• Many conservation biologists attempt to track
  populations using techniques and principles of
  population demography
• Demography focuses on the intrinsic factors that
  contribute to a populations growth or decline,
  including age-dependent birth or death rates
• Other factors also influence population dynamics

6
Sp and Landscape Conservation

• Sex-ratios, age-structure, and time of first
  reproduction influence pop dynamics (collectively
  termed LHC)
• E.g. Florida Key deer (small sub-sp) are largely
  restricted to a few islands
• Demographic study found mortality was skewed
  higher for males and 50 of those were car
  collisions

7
Mechanisms of Pop Regulation

• One question frequently asked is why are some
  species rare?
• This is important as we need to understand how
  mechanisms that influence population size can be
  manipulated to increase their size and maintain
  viable populations or rare sp

8
Mechanisms of Pop Regulation

• Howard and Fiske (1911) introduced the concept of
  catastrophic mortality factors and facultative
  mortality factors
• Density-independent and density-dependent factors
  also impact B

9
Mechanisms of Pop Regulation

• Density-independent factors (a) and
  density-dependent factors (bc)

10
Mechanisms of Pop Regulation

• For density-dependent factors to regulated
  population growth, either per capita mortality
  must increase or per capita birth must decrease
  as population density increases
• General groupings of factors
• Inc D or dec B due to a less resources
• Inc D due to inc predation, parasitism
• Inc D or dec B to inc intrasp interactions

11
Mechanisms of Pop Regulation

• Social behavior can play a direct role in
  regulating some animal populations, although they
  typically interact with resouce shortages (food,
  space)
• E.g. HOWR and BEWR

12
Mechanisms of Pop Regulation

• Occasionally density and social behavior have the
  opposite effect in that B may increase or D may
  decrease at intermediate or high densities
• E.g. high densities help pollen transfer (Allele
  effect) or colonial nesters are more successful
  when large colonies

13
Mechanisms of Pop Regulation

• No RS when density is lt50

14
Mechanisms of Pop Regulation

• Special Problems of Small Populations
• There are 4 general causes of extinction genetic
  loss, demographic variability and declines,
  environmental variation and catastrophes
• Another threat is that of demographic
  uncertainty-such as changes in sex-ratio, RS, and
  mortality rates can all change rather quickly and
  randomly

15
Mechanisms of Pop Regulation

• Environmental uncertainty can cause extinction in
  small pop(s) by causing a sudden increase in
  reproductive failure or individual mortality
• E.g. black stilt nesting biology in braided rivers

16
Mechanisms of Pop Regulation

• Natural catastrophes can also have dramatic
  impacts on populations and should be accounted
  for
• E.g. reintroductions frequently occur on multiple
  sites to diminish the potential of a single
  catastrophic event eliminating all populations

17
Source-sink Concepts

• A metapopulation structured by source sink
  dynamics (not all sites equally likely to go
  extinct)

18
Source-sink Concepts

• It is important that conservationists distinguish
  between areas of high density and productive
  areas (van Horne 1983)
• Just theory?
• Florida Key deer occur mainly on Big Pine Key and
  another. Development has resulted in one end
  being a source (?1.02 vs. ?0.87) with 15
  dispersal

19
Source-sink Concepts

• Dynamics on Big Pine Key

20
Source-sink Concepts

• Peregrine falcons had dramatic declines due to
  ___
• Since then they have recovered, but not the
  coastal population

21
Source-sink Concepts

• Contrasting dynamics of N and Coastal
  pop(n)...urban pop(n) a pleasant surprise

Population was supplemented with translocated
young important due to poor dispersal
22
Source-sink Concepts

• The status of source-sinks can vary between years
• In good years, even poor habitat may produce a
  surplus
• There is also balanced dispersal in which
  movement may simply occur due to carrying
  capacity such that dispersal is due to saturated
  habitat, not necessarily a source

23
Metapopulations and Thresholds

• There has been relatively good evidence that this
  paradigm applies to a variety of organisms
• E.g. mountain lions and riparian corridors
• Read and understand Essay 12.1, 12.2, and 12.3

24
Metapopulations and Thresholds

• There has been a number of theoretical
  advancements in the area of population dynamics,
  especially in a spatially-explicit landscape
• Populations that appear relatively safe may
  suddenly decline if they are subject to threshold
  responses
• These are when disproportionate pop(n) declines
  associated with habitat loss

25
Metapopulations and Thresholds

• Good evidence from a wood frog and spotted
  salamander in ME that as forest cover declines,
  the ponds occupied by breeding individuals
  declines drastically as well
• Of course, some patchily distributed sp may look
  like they have metapop(n) dynamics, but may be
  temporally disjunct (i.e. early succ sp)

26
Modeling Approaches

• There are many problems with conservation biology
• Triage-based
• Lacking information
• Lack replicates
• However, agencies want quantitative models that
  predict the fate of populations or can be used to
  compare different approaches

27
Modeling ApproachesPopulation Viability Analysis

• PVA examines the demographic effect of different
  threats or management practices on a pop(n)
• It is essentially a quantitative risk analysis
  and can compartmentalize various stages (e.g. juv
  surv, fecundity)
• In most cases, the data required for a sound PVA
  is relatively large (Essay 12.2)

28
Modeling ApproachesPopulation Viability Analysis

• There are concerns over the quality of PVA as
  there can be many assumptions or unknowns
• Brook et al. (2000) conducted retrospective PVAs
  on 21 long-term data sets from birds and mammals
  (using first ½ of data)
• Largely accurate (but v. good datasets)

29
Modeling ApproachesPopulation Viability Analysis

• Habitat-based PVAs can help understand how
  landscape changes (anthropogenic or natural) can
  impact the viability of a population

30
How to Determine Viability

• Population trend data
• Detailed demographic data
• Habitat potentials

31
Determining Impact

• Develop predictive models that estimates
  probability of occurrence of target species in
  suitable habitat.
• Apply models to different plan alternatives.
• Translate habitat into population viability.
• Predict populations viability over the next 50
  years under all alternatives.

32
Five Hypothetical Management Alternatives

• Simulated CNF under five scenarios
• no disturbance
• no harvest
• expected harvest
• 200 (2x expected harvest)
• 300 (3x expected harvest)

33
Predicting Population Viability

• Assume that sufficient habitat is required to
  support 250 breeding pairs per species.
• Calculate mean territory size from literature.
• Divide high probability habitat units by mean
  territory size to determine pairs supported.

34
Acadian Flycatcher
35
Acadian Flycatcher
suitable habitat
36
Acadian Flycatcher(4,300 to 9,200 13,700 pairs)
37
Chestnut-sided Warbler
38
Chestnut-sidedWarbler
suitable habitat
39
Chestnut-sided Warbler(400 to 250 790 pairs)
40
Conclusions from Klaus (1999)

• All species considered (n6) have viable
  populations from 1993-2053 in almost all
  simulations
• Late succession species populations increase as
  forest matured over time
• Early succession species populations decrease as
  forest matures
• Some less common early succession species under
  certain management alternatives may fall below
  minimum viable population levels as the forest
  matures over time

41
Hierarchical Analysis

• Most models of population dynamics project future
  population sizes based on current pop(n) size and
  per capita birth and death rates
• Some models attempt to incorporate the causal
  factors that determine the birth and death rates,
  which may operate at more than one level in a
  hierarchy of causation

42
Hierarchical Analysis

• For example, sparrow birth and death rates are
  largely regulated by food supply
• Sparrows live primarily in early successional
  habitats and the availability may vary on a
  number of complex factors dramatically

43
Hierarchical Analysis

• Thus, local factors can regulate local pop(s)
  while regional agricultural practices may
  regulate sparrow abundance at another level
• We could build a habitat-specific demographic
  model to assess future pop(n) based upon 2
  assumptions

1) Demographics dont change
2) Fraction of habitat doesnt change
44
Hierarchical Analysis

• There are hierarchical processes affecting pop(s)
  at different levels
• Changes in habitat availability (and
  accessibility) determine how much suitable
  habitat exists for a given species

45
Hierarchical Analysis

• Consider a region where individual-level and
  landscape level factors both matter
• Yellowstone, winter, brucellosis landscape

Oh yeah, and elk
46
Landscape Models

• Individuals move about the landscape and as such,
  interconnnectedness is extremely important to all
  populations
• Since there is variability across the landscape,
  CB are adopting a landscape perspective when
  designing management plans and analyzing what
  factors impact populations

47
Landscape Models

• Consequently, landscape paradigms are being
  widely considered and adopted
• E.g. source-sink dynamics, metapopulation
  dynamics, thresholds effects, regional landuse
  patterns (in and out of management units)

48
Landscape Models

• One task of conservation biologists is to
  identify and quantify suitable habitat
• To do this, a sound understanding of the local
  and landscape niche is necessary
• Frequently, suitable habitat is found in a
  relatively unsuitable habitat matrix

49
Landscape Models

• BASP breeds in both older-growth pine and
  clear-cuts, but not middle aged forests

Note the spatio-temporal variation in suitable
habitat
Suitable habitat in a) 1970 b) 1990 and c) 2010
50
Landscape Models

• Landscape models can inform conservation efforts
• Only a small portion of each reserve is suitable
  for bamboo
• Increases ecotourism
• Infrastructure demands increased

51
Spatially Explicit Pop(n) Models

• One of the primary themes of landscape biology is
  the importance of subtle landscape aspects (e.g.
  configuration)
• SEPM incorporate actual locations of individuals
  in suitable habitat and consider the movement
  among them
• 3 major elements a landscape map, some landscape
  change, pop(n) simulation

52
Spatially Explicit Pop(n) Models

• Northern Spotted Owl simulations that vary only
  on the configuration of suitable habitat
• random

53
Spatially Explicit Pop(n) Models

• Suitable habitat in a single large patch

54
Spatially Explicit Pop(n) Models

• Clusters of suitable habitat surrounded by
  marginal habitat

55
Spatially Explicit Pop(n) Models

• SEPM have been used to better understand how
  different water management regimes in the
  Everglades might affect fish and wading bird
  pop(s)
• Although field results are qualitatively correct,
  they cannot predict more than 20-40 of variation
  in fish density
• Why?

56
Challenges and Opportunities

• In addition to simply trying to assess
  viability of populations, it is also necessary to
  project ecological, social, and economic
  influences that will alter how humans interact
  across the landscape (remember panda)
• Incorporating alternative-future analysis makes
  use of several distinct options

57
Challenges and Opportunities

• Alternative futures considered and several new
  conservation and restoration opportunities were
  identified

58
Challenges and Opportunities