Core the whole core and nothing but the
Core, the whole core and nothing but the core…….
Defining core habitat, examples �Mountain Quail ◦ A contiguous area of habitat of medium to high quality that has an area greater than two home ranges in size ◦ In continuous use by the species successful enough to produce offspring that disperses �Marten ◦ 30 to 50 square km, 75% of which is suitable stands ( overstory of at least 40% cedar, spruce, pine that has a canopy closure > 75%)
Defining core habitat, examples �Coachella Lizard ◦ Shall contain populations of sufficient size to be considered viable independent of others ◦ Core cannot be fragmented by roads or development ◦ Core has intact processes including sand source and delivery system for the lizard ◦ Each contains a sand source �Salmon ◦ Core areas that functionally control the spatial structure of salmon populations
Defining core habitat, examples �Salmon, continued ◦ biologically suitable (capable of supporting life phase function) ◦ temporally persistent (spatially fixed and have a high potential for habitat rejuvenation), ◦ located within or adjacent to a migratory corridor, ◦ accessible most of the time (not dependent on low return interval events to facilitate access), and ◦ cumulatively large (support significant portion of population).
Defining core habitat, examples �Forest (bird conservation) ◦ interior core, forest that is 1 km or more from a hostile edge ◦ Patch: an area > 200 ha of interior core ◦ Core: an are > 500 ha of interior core �Grizzly Bear ◦ Suitable habitat: based upon road density, building density, land cover, and amount of forest and grassland ◦ Core areas: contiguous areas > 250 square km. with a habitat effectiveness > 3. 0 Core is that area that is at least. 31 miles from any road, motorized trail, or non-motorized high-use trail open during active bear season (Montana Dept of Environmental Quality)
Defining core habitat, examples � Prairie Chicken core habitat as patches of suitable habitat (mixed grass prairie, sandhill prairie, tallgrass prairie, sand sagebrush or shinnery) that are: ◦ more than 2, 000 ha in area, or ◦ between 500 ha to 2, 000 ha in area and no more than 10 km from another patch of at least 500 ha in size � Tiger in Sumutra ◦ Core is comprised of the highest quality habitat > 200 square km ◦ Provided that the area has a high proportion of occupation based upon radio-collar GPS data
Defining core habitat, examples �Veery ◦ Deciduous/mixed forests ◦ Small Core area: size > 27 ha, surrounded by a forest buffer of 100 m. ◦ Large core: size > 100 ha. �Black bear, river otter, moose (Vermont) ◦ Habitat suitability= LCLU*. 275 + house density *. 45 + core habitat *. 275 ◦ Large core: >10, 000 acres ◦ Medium core: > 1500 to 10, 000 acres ◦ Small core: 0 -1500 acres!!!!
Starting assumptions �A map of habitat suitability ◦ May be based upon WHR model ◦ May be determined by GARP, ecological niche, or other technique ◦ May be based upon telemetry data, sitings, etc. ◦ Could be processed by kernel density function, convex hull, etc. �The task at hand is to delineate what is “core”
Defining terms �Suitable Habitat: land cover, populations, and other factors that support the needs of a given species or ensemble/community �Core habitat: an area of suitable size, shape and high quality ◦ Excludes buffer habitat, when hostile edges exist ◦ Includes needed processes �Patch: �Corridors: areas that support connections between core areas
Can GIS do the rest? �After the definition of what core is, is the rest just a problem of using GIS functionality to map it? �OR…is this problem deceptively simple and is as complex as the other 14 steps of the book?
Processes to Delineate Core � Start with a Map of habitat suitability/quality ◦ This needs to be ratio-scaled values if at all possible, discussion � Definition of core: ◦ Size, shape, quality, etc � Approaches used to identify where core areas exist ◦ Merging of suitability levels that meet criteria ◦ Methods used to average surrounding units: e. g. focal mean ◦ Buffers for eliminating edge effects ◦ Examples using bear and owl ◦ Habitat map > “Core” Metric of Fragstats/Patch Analyst � Spatial analysis methods for Core habitat ◦ R-separation method for estimating effective core size ◦ PGP to determine that a given area contains needed suitable features, useful to model home range core, activity centers, and sub units like territorial patches capable of supporting a demographic unit
Processes to Delineate Core � Start with a Map of habitat suitability/quality � Definition of core: � Existing approaches used to identify where core areas exist � ◦ This needs to be ratio-scaled values if at all possible, discussion ◦ Size, shape, quality, etc ◦ ◦ ◦ ◦ Fragstats Patch analyst & Patch Morph Merging of suitability levels that meet criteria Methods used to average surrounding units: e. g. focal mean Buffers for eliminating edge effects Examples using bear and owl Habitat map > “Core” Metric of Fragstats/Patch Analyst Spatial analysis methods for Core habitat ◦ R-separation method for estimating effective core size ◦ PGP to determine that a given area contains needed suitable features, useful to model home range core, activity centers, and sub units like territorial patches capable of supporting a demographic unit
Mapping Core Habitat �Select those areas of suitable habitat that are large enough to meet threshold criteria �Buffer-defined core: ◦ Excludes buffer habitat, when hostile edges exist �Density-defined core: �PGP-defined core: (not included, but) �Core effectiveness:
Fragstats & Patch Analyst habitat representation Fragstats requires a map, raster or vector, that represents habitat and other Habitat Matrix
Buffer defined Core Patch Analyst calculates core as habitat minus buffer Core habitat Habitat Matrix
Buffer defined Core (BDC) Fragstats calculates core as habitat minus buffer Using the same buffer creates a different core! Core habitat Habitat Matrix
Patch Morph Do two patches really exist, is this a data error issue, is it a grain size issue? Given rules, patch Morph might decide that it is one patch Habitat Matrix
Patch Morph Do two patches really exist, is this a data error issue, is it a grain size issue? Given rules, patch Morph will create a combined patch Habitat Matrix
Patch Morph (BDC) Do two patches really exist, is this a data error issue, is it a grain size issue? Now, core may be mapped where habitat doesn’t really exist! Habitat Matrix Core
Density–defined core
Density–defined core 50% canopy cover within a six hundred acre moving window
Within the Kings Canyon region of the Sierra National Forest, modeled “Core” spotted owl habitat is shown as light brown to dark brown (based upon density defined core) A key question: what can this support, how effective can this core be due to its undulating nature?
Modeling Effective Core � Estimating effective core by building biologically defined/feasible patches (Gilpin and others) PGP � Estimating effective core by the use of rseparation location model (RLSM)
RSLM - Effective Core If a circular area of size R composed of core habitat is large enough to support a territorial species, then how many circular territories can be drawn within an area of core habitat without overlapping?
RSLM - Scatter. Max Method: Random Maximum Scatter (assume a raster) Step 1: From the core habitat, identify those raster cells which can serve as territorial centers. Define this as list , set k=0 , set null and go to step 2. Step 2: Select from random a cell j from list. 3. Step 3: Remove from list step 4 Step 4: If list is empty, stop with set F containing k centers whose territories do not overlap. Otherwise return to step 2. Place cell j on list F, increment k by 1, and proceed to step all cells that are less than 2*R distance away from cell j and then proceed to
Effective Core - Scatter. Max
RSLM - Heuristic Method: RSLM heuristic Step 1: From the core habitat, identify those raster cells which can serve as territorial centers. Define this as list , set k=0, set null and go to step 2. Step 2: Select from random a cell j from list to step 3. Step 3: Remove from list step 4. Step 4: If k<4, find the cell in that minimizes the combined distances to the first k sites already in F. Make this the site of set F, increment k to k+1 and return to step 3. If then go to step 5. If list is empty, stop with set F containing k centers whose territories do not overlap. otherwise proceed to step 6 Step 5: . Place cell j on list F and increment k by 1 and proceed all cells that are less than 2*R distance away from cell j and then proceed to Step 6: Find a cell in that minimizes the combined distances to the first 4 sites selected in set F. Make this the site of set F, increment k to k+1 and then proceed to step 7. Step 7: Remove from list step 5. all cells that are less than 2*R distance away from cell j and then return to
Effective Core – RSLM heuristic
The question we wish to address is how many owls will this habitat support? We need a model to calculate effectively useable habitat Conceptually, we might want to know how many circular territories can we draw on the map that do not overlap, and which are centered on a cell in which the average canopy cover is greater than 50%?
Final suitability values grid:
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