Protecting ecosystems
Chapter 11
The goals of protected areas
¡ Preservation of large, intact, relatively unimpacted ecosystems (e.g. watersheds)
¡ Biodiversity conservation (e.g. areas of high endemism)
¡ Preservation of particular species or groups of species (e.g. large carnivores)
¡ Conservation for sustainable exploitation of natural resources
Concerns in protected areas siting and design
¡ Biological concerns, and implications to size, siting, shape, landscape context, etc.
¡ Sociocultural concerns, implications to traditional land uses
¡ Economic concerns, and implications to local and regional economies
IUCN protected areas classification
Strict nature reserves
Wilderness area
National park
Natural monument
Habitat management area
Protected landscape
Managed resource protection area
Single-species reserves and the umbrella concept
¡ If the flagship species are area-sensitive and require large amounts of habitat, their protection may lead to protection of entire ecosystems and many other species
Some important flagship/umbrella species
Key criteria for locating protected areas
¡ Areas of high biodiversity
¡ Areas of high vulnerability
¡ Preserve system with complete representativeness
¡ Preserve system with high complementarity
Locating protected areas: biodiversity
¡ To focus conservation issues on regions of the landscape where biodiversity is greatest
¡ Locate reserves on environments and communities that have high biodiversity
Identifying reserves
Locating protected areas: vulnerability
¡ To focus conservation issues on regions of the landscape where anthropogenic stress is depleting biodiversity
¡ Locate reserves on environments and communities that are least likely to persist under stress (i.e.risk/threats are greatest)
Locating protected areas: representativeness
¡ A “representative” system of protected areas within a region includes all the natural range of diversity in a region, protected in such a manner that these elements will continue to persist
¡ Usually “units” of representation are defined by major vegetational communities
Locating protected areas: complementarity
¡ Once representation targets have been identified, we can determine whether a proposed protected area contains features that are absent or under-represented in the existing protected area network
¡ If it does, it has high complementarity. If it duplicates features that are already well-represented, it has low complemetarity
Geographic information systems (GIS)
Hotspots
Reserve selection constrained by human presence
Reserve design
¡ Size
¡ Number
¡ Isolation
¡ Arrangment
¡ Connectivity
¡ Shape
Additional critical issues in protected areas design
¡ Heterogeneity and dynamics
¡ Landscape context
¡ Biotic versus jurisdictional boundaries
Reserve size: implications from island biogeography
¡ As size increases, large herbivore richness in east African parks increases...
¡ …because the larger the area, the lower the local extinction rate
Loss of large mammals since European settlement in the northern Rocky Mountains
¡ Loss increases with decreasing size of isolated ranges
¡ Therefore, small isolated ranges are not sufficient to maintain large mammal diversity
Natural mammal extinctions in North American national parks
¡ In 14 western North American parks, the number of natural extinctions occurring after park establishment decreases with park area
Park size and population sizes
¡ Population size increases with park size, suggesting that population size is limited by habitat availability
¡ Larger parks are required to maintain viable populations of large herbivores and (especially) carnivores
Edge effects
¡ Ecological/biotic influences which occur within areas of “natural habitat” in close proximity to modified habitats
¡ Includes changes in microclimate, predation, invasion of exotics (particularly weedy species), and human disturbance
Reserve size and edge effects
¡ As size decreases, ratio of edge to interior increases
¡ So, for a given size of edge effects, smaller reserves will be more affected than larger reserves
Why bigger reserves are better: summary
¡ Species richness increases with size
¡ Larger reserves are able to maintain larger populations, especially of large mammals and birds
¡ Edge/interior ratios are minimized
Size of parks and protected areas: the global perspective
¡ Almost 50% are less than 100 km2, 98% less than 10,000 km2
¡ Given small sizes, it is very unlikely that some area-sensitive species can be maintained without active management
No park is an island: conservation of large herbivores in East Africa
¡ Virtually all parks are expected to lose biodiversity over time if surrounding lands are not managed in a manner consistent with biodiversity conservation
Reserve shape and edge effects
¡ Long, narrow designs are mostly edge
¡ Circular designs of the same area have some true interior habitat
Heterogeneity and Patch Dynamics
Effects of habitat loss on reserves of different shapes
¡ In circular designs, loss of edge habitat can dramatically reduce the size of the core habitat
The role of buffer zones
¡ Cushion impacts of external threats
¡ Accommodate multiple uses while minimizing impacts on biodiversity and ecosystem structure/function
¡ Minimize edge effects on core areas
Reserve design: buffer zones and transitions
¡ Central core in which human disturbance is minimal
¡ Buffer zone which protects core area
¡ Transition zone between external landscape and preserve
Asinara Island Marine Reserve
Corridors and reserve networks
¡ Corridors promote movement and recolonization among high-quality habitats (often protected areas) in fragmented landscapes
¡ Routes for migratory species, joining different habitat types
¡ Permanent movement of individuals among habitats for species with metapopulation structure
Corridors for migratory species: Lake Manyara and Tarangire National Parks in northeastern Tanzania
¡ The proposed game corridor is designed to allow migratory ungulates to move freely between traditional grazing areas
Corridors for species with metapopulation structure
¡ Size and quality of corridor determines recolonization rates
¡ Small, low quality corridors increases extinction rate of sinks
Tiger reserve design
Estimates of minimum effective corridor width
¡ The larger the species, the larger the corridor required for movement
¡ Large carnivores especially require wide corridors of suitable habitat
Corridors as building blocks of protected area networks: the Klamath region in California/Oregon
¡ Proposed corridors would link existing protected areas, and be sufficiently large to allow movement of area-sensitive species
Multiple-use networks and corridors
¡ Nodes of existing protected areas are linked by riparian and coastal corridors
Multiple-use regional networks
¡ Includes core reserves, corridors and buffer zones
Reserve design: general principles
¡ large > small
¡ one large > several small*
¡ close together > further apart
¡ * debatable!
Reserve design: general principles
¡ corridors > no corridors
¡ round > linear
¡ buffer zones/transition zones > no buffers
Jurisdictional and biotic reserve boundaries: the 8 largest reserves in western North America
¡ Jurisdictional boundaries of protected areas should, whenever possible, correspond to ecological boundaries
¡ 7/8 had legal boundaries significantly smaller than biotic boundaries
¡ 7/8 had boundaries smaller than the minimal area requirements of one or more large mammal species
Reserve planning in Vietnam
Ecosystems as equilibrium systems
¡ Equilibrium view: natural ecosystems have a single, balanced equilibrium state
¡ If disturbed, ecosystems will return to their balanced state
Conservation implications of the equilibrium view
¡ Ecosystems can be preserved within isolated reserves of sufficient size
¡ Ecosystems will maintain themselves in a stable state
¡ If disturbed, ecosystems will return to their equilibrium state
Ecosystems as non-equilibrium systems
¡ Non-equilibrium view: ecosystems naturally in a state of flux with several possible alternate states
¡ If disturbed, ecosystems may move to a different state
Conservation implications of the non-equilibrium view
¡ Ecosystems are not easily preserved in isolated reserves
¡ Reserves are unlikely to maintain themselves in a single stable state
¡ Natural disturbance, in addition to human disturbance, will cause reserves to change over time