Landscape Conservation - Introduction to Conservation Biology - Lecture Slides, Slides of Biology

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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) Docsity.com 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 Docsity.com 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 population’s growth or decline, including age- dependent birth or death rates • Other factors also influence population dynamics Docsity.com 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 Docsity.com 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 Docsity.com 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 Docsity.com 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 Docsity.com 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 Docsity.com 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 Docsity.com 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 Docsity.com Source-sink Concepts • A metapopulation structured by source sink dynamics (not all sites equally likely to go extinct) Docsity.com Source-sink Concepts • Peregrine falcons had dramatic declines due to ___ • Since then they have recovered, but not the coastal population Docsity.com 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 Docsity.com 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 Docsity.com 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) Docsity.com 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 Docsity.com Modeling Approaches Population 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) Docsity.com How to Determine Viability • Population trend data • Detailed demographic data • Habitat potentials Docsity.com 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. Docsity.com Five Hypothetical Management Alternatives • Simulated CNF under five scenarios – no disturbance – no harvest – expected harvest – 200% (2x expected harvest) – 300% (3x expected harvest) Docsity.com 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 Docsity.com 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 Docsity.com 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 don’t change 2) Fraction of habitat doesn’t change Docsity.com 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 Docsity.com 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) Docsity.com 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 Docsity.com 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 Docsity.com Spatially Explicit Pop(n) Models • Northern Spotted Owl simulations that vary only on the configuration of suitable habitat • random Docsity.com Spatially Explicit Pop(n) Models • Suitable habitat in a single large patch Docsity.com 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 Docsity.com Challenges and Opportunities • Alternative futures considered and several new conservation and restoration opportunities were identified Docsity.com