HOW MUCH IS ENOUGH? Conservation planning at
multiple scales
Mark Anderson, PhDMark Anderson, PhDDirector of Conservation ScienceDirector of Conservation Science
Eastern U.S. Conservation RegionEastern U.S. Conservation RegionThe Nature ConservancyThe Nature Conservancy
31 October 200431 October 2004Land Trust Alliance RallyLand Trust Alliance Rally
Critical Concepts
• Ecosystem Function: How big does an example of a feature have to be?
• Replication and Redundancy: How many examples do we need to protect?
• Sources and Sinks: What is the role of the protected example in relationship to the surrounding landscape?
How large does a forest have to be?
How large does a forest have to be?
• Minimum Dynamic Area: Big enough to absorb, buffer and benefit from catastrophic disturbances expected over centuries
• Species Area Requirements: Big enough to ensure long-term persistence of species that need or thrive under interior forest conditions
DisturbanDisturbanceceExample Forest - Example Forest - In 300 Years:In 300 Years:-15 Fires15 Fires
-4 Hurricanes4 Hurricanes-7 Windstorms7 Windstorms-InfestationsInfestations-BlightBlight-Disturbances Disturbances the Rule, Not the Rule, Not the Exceptionthe Exception
Critical Concepts
• Most disturbances are small and frequent
• Large infrequent catastrophic disturbances leave lasting impacts on the landscape
• Disturbance is distributed in patches of varying severity
Severe Damage
Patch
Severe Damage Patches in Pisgah Forest NH (from Foster 1988b)
Severe Damage
Patch
- 25% in Early - 25% in Early Successional Successional StateState
- 50% Medium 50% Medium AgedAged
- 25% in Mature 25% in Mature StateState
DisturbanDisturbanceceHow much larger How much larger than the severe than the severe damage patch?damage patch?
Breeding habitat for forest interior species
Ave breeding territories x 25 (sources Gill et al. 2004, DeGraff and Yamasaki 2002, *Robbins 1989.)
Average Breeding Territory x 25
0 5000 10000 15000 20000 25000 30000 35000 40000 45000
Many Warblers
Scarlet tanager
Eastern wood pewee
Spruce Grouse
Nashville Warbler
Black & White Warbler
Pileated woodpecker
Sharp-shinned Hawk
Saw whet owl
Area sensitive songbirds*
Rusty blackbird
Northern goshawk
Barred owl
Broad-winged hawk
American marten
Acres
Minimum tract size for area sensitive birdsfrom Robbins et al. 89, Hamel 92
SPECIES summer tanager black-throated blue
veery cerulean warblerkentucky warbler northern parula
acadian flycatcher canada warblerblue-gray gnatcatcher louisiana waterthrushscarlet tanager black and white warbler
hairy woodpecker worm-eating warblerovenbird red-shouldered hawk
american bittern piliated woodpeckerwhite-breasted nuthatchred-eyed vireo
rose-breasted grosbeakwood thrush
tufted titmousegreat-crested flycatcherred-bellied woodpecker
*unknown sizes:american redstart, brown creeper, chestnut -sided warbler, hermit thrush, hooded warbler,least flycatcher, mourning warbler
0 2 5 25 50 100 500 1000 2000 3000 4000 // 6000
Size in acres
SALT MARSH
100 acres
200 acres
50 acres
Black Duck
SALT MARSH SIZE
Clapper RailSeaside sparrowWillet?
Savannah SparrowSharp tailed Sparrow Sedge Wren
LeastBittern
Black Rail
MINIMUM DYNAMIC AREA ? Nutrient turnover, Flushing,Organic matter accumulation, transformations & storage
Short –eared Owl
SIZE (models, literature)
CONDITION(Ground survey, Corroborating EOs)
LANDSCAPE CONTEXT(GIS metrics, threat maps)
Critical Concept
• Replication across Gradients
• Redundancy to spread risk
GEOLOGY
TOPOGRAPHY
ELEVATION
ROADS
ECO-SYSTEMSHOUSINGDENSITY
DATA EXAMPLES
Ecological Land Units (Geology, Topography and Elevation)
Ecological Land Units were used to insure we identified forest blocks over all landscape types
Initial Minimum Goals
• The number of viable occurrences needed in the Ecoregion is a function of restrictedness and scale
Matrix Large Patch Small PatchRestricted 20 30Limited 15 25Widespread 10 15Peripheral 5 5
DYNAMIC PORTFOLIO• Matrix Forest• Patch Communities & Species• Aquatic networksOptimum solution, alternatives not shown
Source Sink Dynamics(Net exporters of juveniles based on habitat specific fitness)
Source
SinkSink
Sink
Sink
Dispersal Pressure
DISPERSAL PRESSURE
RESERVE
Average Number of Breeding Bird Pairs per 99 Acres
Adapted from Haney,J.C. and C.P.Schaadt.1996.Functional role of eastern old-in promoting forest bird diversity. In M.B.Davis (ed.) Eastern old-growth forests:prospects for rediscovery and recovery. Island Press. Washington DC.
N - DIMENSIONAL PINBALL
“Softening” the matrix between cores
Amplification& Buffering ofCore effects
Snowmelt Wind disturbances
Movement Hydrologic Cycles
The portfolio depicts the critical examples of ecosystems and population occurrences.
Which strategies and how much area are needed to protect those features is the subject of localized efforts, referred to as conservation area planning.
