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Principles of Conservation Biology: an Overview

Principles of Conservation Biology: an Overview

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Principles of Conservation Biology: an Overview

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  1. Principles of Conservation Biology: an Overview Prof. Claire Kremen Univ Cal Berkeley Cal Academy Bioforum Apr 4, 2009

  2. Biodiversity Defined • “Biodiversity is the total variety of life on earth. It includes all genes, species and ecosystems and the ecological processes of which they are a part” (Convention on Biodiversity, 1992)

  3. Ecological interactions • Biodiversity is more than the sum of the parts • Interactions “structure” communities, maintain diversity, and make ecosystems work • e.g. Competition • Predation • Mutualisms (e.g. pollination, seed dispersal)

  4. Evolution and extinction • Biodiversity is not static but constantly changing • 99% of the species that ever lived have gone extinct • Mass extinctions • Background extinctions • Finite lifetimes

  5. Conservation biology • Concerned with loss of biodiversity, not just loss of species • “Fundamental loss of resources in genetics, species, community attributes and ecosystemproperties” • Flip side: maintenance of biodiversity, ecological and evolutionary processes

  6. Why care about biodiversity? • Intrinsic value (Muir, 1838-1914) • All species have value independently of their utility to humans • Utilitarian value (Pinchot, 1865-1946) • Species that provide the “greatest good to the greatest number” (over the longest time) have value • Cons Bio : (Leopold, 1886-1948) • can include both value systems • “To keep every cog and wheel is the first precaution of intelligent tinkering" (Leopold 1943).

  7. Aldo Leopold (1886-1948)Evolutionary-Ecological Land Ethic Biological communities: assemblages of interdependent species Maintaining the health of natural ecosystems and ecological / evolutionary processes Humans exist within the ecological community; depend on ecosystem services Synthetic approach: Both intrinsic value and utilitarian value

  8. Why be concerned about biodiversity loss if extinction is a fact of life? Moderate certainty: current extinction rates > by 100 – 1000 times 10 – 30 % of mammals, birds and amphibians threatened Is extinction outpacing speciation potential?

  9. From Wilcove 1996 Major drivers of endangerment What’s missing?

  10. Threats to terrestrial species • Terrestrial habitat loss • 39-50% of land surface transformation

  11. Result of habitat loss • Reduction in total area  decrease in size, # of populations  local extinctionsfewer species • Reduction in habitat diversity • Reduced species diversity • Cascading effects, co-extinctions

  12. The forested areas of Warwickshire, England From Primack 2002 Habitat fragmentation • Above and beyond habitat loss • Isolation: reduced immigration, re-colonization • Edge effects

  13. Invasion The distribution of species on Earth is becoming more homogenous The rate of invasion is increasing over time HOMOGENIZATION Growth in Number of Marine Species Introductions in North America and Europe

  14. Introduced cheatgrass, Bromus tectorum, has transformed the Great Basin shrub-steppe ecosystem • Has increased fire frequency from once/80 years to once/4 years! • Occupies over 5 million hectares of Great Basin

  15. Climate change effects on biodiversity • Range shifts • Latitudinal range • Altitudinal range • Mis-matched interactions • Reassembled (scrambled) communities • Feedbacks (e.g. vegetation and climate) • Species Endangerment

  16. Climate change endangers polar bears • Sea ice is the key • Bottom up: habitat for micro-algae • Top down: seal hunting ground; corridors to dens • Loss of sea ice  endangers polar bear • Loss of top predator: cascading effects on Arctic food web

  17. Climate change can induce coral reef bleaching http://www.ogp.noaa.gov/misc/coral/98bleaching/ Bleached and normally pigmented Pocillopora colonies

  18. Oceans and Freshwater Aquatic habitats • If anything are more vulnerable to same threats, with enhanced vulnerability to over-exploitation and pollution • Freshwater • USA: Very high endangerment levels in fish & amphibians (25-40%) and crayfish & molluscs (> 60%) compared to terrestrial vertebrates (15-18%

  19. Botsford 1997 Over-exploitation of global ocean fisheries • > 60% of the world’s fisheries are fully to over exploited, or depleted • By-catch increases fish-catch by 30%

  20. Conserving biodiversity • Genetic level: seed, egg, sperm banks • Population and species level – science of managing small populations • Captive breeding (zoos/botanical gardens) • Reintroductions • Population management in the wild • Protection (hunting, disease, habitat) • Genetic management (translocations) • Habitat restoration

  21. Conserving biodiversity: habitat, species, ecosystem level • Protected areas • Managing the matrix • Restoration • Wildlife-friendly agriculture

  22. Protected areas for Biodiversity Conservation • Select the areas that represent and maintain biodiversity over time… (Margules and Pressey 2000)

  23. REPRESENTATION Including as many different ecosystems and species in the reserve network Representing the full range of variation (genetic, ecological) present within target species

  24. Reserve Design Decision-Support • Computer programs • Meet conservation targets (e.g. conserve 20% of each habitat type and 3 populations of each species) at least cost

  25. A network of reserves that represents species efficiently • But it may not be so good at maintaining biodiversity – why not? Site selection in the Sierra Nevada foothills for conservation prioritization Grey = already protected

  26. Maintaining biodiversity over time • Population persistence (viability) • Maintaining ecological processes • E.g. migrations • Maintaining evolutionary processes • Potential for adaptation within populations (genetic diversity) • Selecting areas where rapid speciation is occurring • Response to climate change

  27. Reserve design features for persistence SIZE Edge to area ratio Disturbance regime Shape Environmental gradients Functional units Corridors Matrix habitat CONNECTIVITY

  28. SIZE Larger size  • More species (interactions, functions), S-A relationship • More habitats (interactions, functions) • Larger populations – • Protects vulnerable species • Area demanding: large-bodied, high-trophic level, rare • Habitat specialists (if habitat included) • Species requiring multiple habitat types • Shape Reduced edge/area ratio, edge effects • Disturbance regime: maintenance of disturbance-generated patch heterogeneity • Includes whole functional units • Includes whole environmental gradients

  29. From Primack 2002 SIZE & EDGE EFFECTS Edges create core versus edge habitat Example: many songbirds experience high nest predation near edges in woodlots within sub-urban areas

  30. Meffe & Carroll 1997 Shape and edge effects

  31. DISTURBANCE REGIME • Disturbance promotes habitat heterogeneity • By resetting successional sequence in parts of the landscape • Creating patchiness in the landscape which is determined by the temporal and spatial scale of the disturbance(s)

  32. Spatial and temporal scale of disturbance varies by type

  33. SIZE & DISTURBANCE REGIME • Disturbance promotes habitat heterogeneity • mosaic of patches at different successional stages • Habitat heterogeneity: • supports species requiring multiple habitat types • Supports early successional species (e.g. Heath fritillary butterfly = “Woodman’s follower”) • Size of reserve  ideally as big as or bigger than scale of likely disturbances

  34. Functionally inter-dependent ecosystems:e.g. “a complex, dynamic patchwork of mangroves, sea grass bed and reefs” (Moberg & Ronnback 2003) SIZE & FUNCTIONAL UNITS

  35. Reserve design features for persistence SIZE: Bigger is better! Edge to area ratio Disturbance regime Shape Environmental gradients Functional units Corridors Matrix habitat CONNECTIVITY

  36. CONNECTIVITY • Isolation is a key factor causing loss of species from reserves • Preventing gene flow, maintenance of genetic diversity • Reducing recolonization following extinction (rescue effect) • Preventing access between summer/winter grounds for migratory species • Preventing access to multiple habitat types needed for different life stages • Preventing response to global warming

  37. CONNECTIVITY: Multi-scale responses • RESPONSE • Create corridors between reserves • Manage the matrix around reserves PROBLEM of FRAGMENTATION • Preventing gene flow, maintenance of genetic diversity • Reducing recolonization following extinction (rescue effect) • Preventing access between summer/winter grounds for migratory species • Preventing access to multiple habitat types needed for different life stages • Preventing response to global warming

  38. Wildlife overpass Transportation Equity Act for the 21st Century provides funding http://www.fhwa.dot.gov/environment/wildlifecrossings/overview.htm

  39. Managing the Matrix Making matrix “friendly” to wildlife -- Reserve zonation: core, buffer, transition -- Wildlife friendly farming/Restoration Noss and Cooperrider 1994,modified from Harris 1984

  40. CONNECTIVITY: Multi-scale responses • RESPONSE • Create corridors between reserves • Manage the matrix around reserves • Protect migratory routes/stop-overs PROBLEM of FRAGMENTATION • Preventing gene flow, maintenance of genetic diversity • Reducing recolonization following extinction (rescue effect) • Preventing access between summer/winter grounds for migratory species • Preventing access to multiple habitat types needed for different life stages • Preventing response to global warming

  41. Stop-over sites along songbird migration routes • Neotropical birds • Use radar to detect nocturnal bird movement • Timed to get departure events from stopover points (20-40 min after sunset) • Signal characteristics Breeding wintering http://www.njaudubon.org/Education/Oases/RadImages.html

  42. CONNECTIVITY: Multi-scale responses • RESPONSE • Create corridors between reserves • Manage the matrix around reserves • Protect migratory routes/stop-overs • Include whole functional units, disturbance regimes, environmental gradients within reserves or reserve networks • Include elevational or latitudinal gradients within reserves PROBLEM of FRAGMENTATION • Preventing gene flow, maintenance of genetic diversity • Reducing recolonization following extinction (rescue effect) • Preventing access between summer/winter grounds for migratory species • Preventing access to multiple habitat types needed for different life stages • Preventing response to global warming

  43. Designing Masoala National Park, Madagascar • Habitat heterogeneity – connectedness between habitats, marine and terrestrial • Species response to climate change: Include elevational gradients within reserve • Masoala, Madagascar

  44. New Reserve Design Methods • Represent species or habitats efficiently • Minimize edge effects, maximize clustering • Maximize connectivity Leslie et al. 2003 Ecol App.

  45. Conclusions • Biodiversity has great value, both intrinsically, and also because human life depends on it • But, it is under threat, from habitat loss and degradation, invasive species, climate change, pollution and over-exploitation • Conservation biologists have many tools to protect biological diversity, from genetic to ecosystem levels.

  46. Conclusions • Protected areas are an important tool for biodiversity conservation. • The design of protected areas and reserve networks should foster representation of biodiversity and its persistence. • Reserves need to be sited efficiently to represent biodiversity. • Size, shape and connectivity of reserves and relationship with the surrounding landscape matrix are essential considerations for biodiversity persistence.