Inland Hubs
These are the hubs used in the Linkage Mapper-based connectivity analysis for the inland portion of the South Atlantic area in Blueprint 2020.
Input Data
Mapping Steps
- Rebalanced ecosystem integrity scores for each inland subregion were mosaiced together into one raster. Areas in the highest scoring 10% of the inland 2020 South Atlantic Blueprint extent (based on ecosystem integrity scores) were identified as potential hubs.
- Outside of the 2020 South Atlantic Blueprint extent, we used local connectedness from TNC’s Resilient Land Project. Areas ≥ 1 standard deviation above average were identified as potential hubs.
- We selected polygons from TNC’s Secured Lands Database (External Eastern Division 2018) that were in GAP Status 1 - Permanent Protection for Biodiversity, 2 - Permanent Protection to Maintain a Primarily Natural State, 3 - Permanently Secured for Multiple Uses, or 9 - Unknown GAP status.
- Since military-owned lands are often protected for training or defense rather than conservation, we removed any polygons that listed the Fee Owner as U.S. Department of the Army, U.S. Department of Defense, U.S. Air Force, or U.S. Department of the Navy.
- We converted this polygon layer to a raster with a cell size of 200 m using a maximum combined area cell assignment. The 200 m cell size was a relic from the previous Blueprint that we did not catch in time to correct for Blueprint 2020. In the next revision cycle, we will use a cell size that matches current Blueprint resolution (likely 30 m). Converting the data to a raster helped identify large patches of secured lands that are near one another, but separated by a narrow linear feature like a river or road. It also allowed us to combine tracts that are contiguous but differ in ownership.
- We combined potential hubs from the ecosystem integrity scores (step 1., TNC Resilience Project (step 2), and Secured Lands (step 5).
- We removed areas identified as reservoirs from the hubs to match our approach to reservoirs in the rest of Blueprint 2020.
- Contiguous patches greater than 2,000 ha (5,000 acres) in size were kept as hubs. We identified these patches using the ArcGIS Spatial Analyst-Region Group function (8-neighbor). This size threshold from Hoctor et. al (2000) is also used In the Florida Conservation Blueprint to the south for connectivity purposes.
- The raster patches were converted to polygons.
- All resulting polygons either within the 2020 South Atlantic Blueprint extent or within 26.1 km of the 2020 South Atlantic Blueprint extent were used as inland hubs in the Linkage Mapper analysis. The distance of 26.1 km is based on dispersal distances of subadult black bears (White et al. 2000), a species that disperses from within the South Atlantic into all other adjacent areas.
Inland Corridors
This is the corridor raster used in the inland portion of the South Atlantic area in Blueprint 2020.
Input Data
- Rebalanced ecosystem integrity scores for each inland subregion
- TNC’s Resilient Land Project
- Blueprint 2020 Inland Hubs (created above)
Mapping Steps
- Rebalanced ecosystem integrity scores for each inland subregion were mosaiced together into one raster.
- We used the local connectedness layers from TNC’s Resilient Land Project to fill in a buffer area around the South Atlantic geography. This allowed corridors to connect from inside the South Atlantic geography into the neighboring landscapes.
- To create a single resistance layer, we rescaled and inverted the inland ecosystem integrity scores (within the South Atlantic boundaries) and the local connectedness metric (outside the South Atlantic boundaries) to ensure they used the same scale and that high values represented high resistance.
- We resampled the resistance layer from 30 m to 90 m resolution, to allow us to run it in Linkage Mapper.
- We performed a Linkage Mapper corridor analysis in ArcMap V 10.7.1 using the following Parameters: [‘C:\Linkage_Mapper_2_0_0\toolbox\scripts\lm_master.py’, ‘C:\LM4’, ‘C:\LM4\LM4in.gdb\Hubs’, ‘gridcode’, ‘C:\LM4\LM4in.gdb\MosaicTNCBlend90’, ‘true’, ‘true’, ‘Cost-Weighted & Euclidean’, ‘C:\LM4\Hubs_dists.txt’, ‘true’, ‘true’, ‘true’, ‘4’, ‘Cost-Weighted’, ‘true’, ‘true’, ‘true’, ‘200000’, ‘165000’, ‘#’, ‘#’, ‘#’, ‘#’]
- Linkage Mapper outputs a corridor raster with a continuous surface. We used the ArcGIS-Slice function to identify the top 24% of the corridor surface by area.
- We then removed corridors that ran through reservoirs, to be consistent with how we treated reservoirs in the rest of the 2020 Blueprint. This result is the “inland corridor” layer you see in this map service. Inland corridor pixels not already identified as highest, high or medium priority were incorporated into Blueprint 2020 as the “corridor” class. We chose a 24% cutoff because it resulted in a corridor area of approximately 5% of the South Atlantic inland area (not already covered by highest, high, or medium priority pixels).
Marine Hubs
These are the hubs used in the Linkage Mapper-based corridor analysis for the marine portion of the South Atlantic area in Blueprint 2.2.
Input Data
Mapping Steps
- The highest scoring 10% of the marine area (based on integrity scores) were identified as potential hubs in the marine ecosystem. We used the ArcGIS Spatial Analyst-Region Group function to identify patches of these top 10% areas. Contiguous patches greater than 2000 ha were kept as hubs. This is consistent with terrestrial hubs but also within the 2-10 km width recommended by Krueck et al (2017). These patches were identified using the ArcGIS Spatial Analyst-Region Group function (4-neighbor).
- All open water estuary pixels were considered potential hubs. We performed a Region Group analysis on the open water estuary ecosystem map to identify patches. Contiguous patches greater than 2000 ha were kept as hubs to encourage connectivity from all large estuaries to the highest priority marine hubs. These patches were identified using the ArcGIS Spatial Analyst-Region Group function (8-neighbor).
- We converted the raster patches to polygons for use in Linkage Mapper.
Marine Corridors
This is the corridor raster used in the marine portion of the South Atlantic area in Blueprint 2.2.
Input Data
Mapping Steps
- The estuarine open water ecosystem is only covered by one indicator in Blueprint 2.2, coastal condition, which made it unnecessary to perform a Zonation run to prioritize open water estuaries. However, to perform a corridor analysis to connect open water estuaries with the marine ecosystem, we needed to create a layer comparable to the Blueprint 2.2 marine ecosystem integrity score. To do this, we clipped the coastal condition indicator to the estuarine open water ecosystem. Coastal condition has values ranging from 1.13 to 5. We rescaled these values to range from 0-1 using a linear transformation function.
- To create a single resistance layer, we mosaiced, rescaled, and inverted the coastal condition indicator and the marine ecosystem integrity score (from Zonation) so that high values represented high resistance.
- We performed a Linkage Mapper corridor analysis using the following Parameters: [‘C:\LinkageMapper_1_1_0\toolbox\scripts\lm_master.py’, ‘C:\LinkMap\LM_2_2_MarineB’, ‘C:\LinkMap\LM_2_2_MarineB\LM_Input_Marine_20170302.gdb\MarineTop10_EstuariesOpenWater_HubsMergePD’, ‘gridcode’, ‘C:\LinkMap\LM_2_2_MarineB\LM_Input_Marine_20170302.gdb\MarineOpenWaterEstuarySurfaceLinearRescaleInv’, ‘true’, ‘true’, ‘Cost-Weighted & Euclidean’, ‘#’, ‘true’, ‘true’, ‘true’, ‘4’, ‘Cost-Weighted’, ‘true’, ‘true’, ‘#’, ‘#’, ‘#’]
- Linkage Mapper outputs a corridor raster with a continuous surface. We used the ArcGIS-Slice function to identify the top 35% of the corridor surface by area. This result is this “marine corridor” layer. Marine corridor pixels not already covered by highest, high or medium priority pixels were incorporated into Blueprint 2.1 as the corridor class. We chose a 35% cutoff because it resulted in a corridor area of approximately 5% of the South Atlantic marine environment (not already covered by highest, high, or medium priority pixels).
Literature Cited
Anderson, M.G., A. Barnett, M. Clark, C. Ferree, A. Olivero Sheldon, J. Prince. 2016. Resilient Sites for Terrestrial Conservation in Eastern North America. The Nature Conservancy, Eastern Conservation Science.
Hoctor, T. S., M. H. Carr, P. D. Zwick. 2000. Identifying a linked reserve system using a regional landscape approach: the Florida ecological network. Conservation Biology 14:984-1000.
Krueck, N. C., Legrand, C., Ahmadia, G. N., Estradivari, E., Green, A., Jones, G. P., Riginos, C., Treml, E. A. and Mumby, P. J. 2017. Reserve Sizes Needed to Protect Coral Reef Fishes. Conservation Letters. Accepted Author Manuscript. doi:10.1111/conl.12415
McRae, B. and Kavanagh, D. Linkage Mapper User Guide: Version 1.0. 2014. [http://www.circuitscape.org/linkagemapper].
Moilanen, A., Pouzols, F. M, Meller, L., Veach, V., Arponen, A., Leppänen, J. Kujala, H. Zonation Version 4 User Manual: Spatial conservation planning methods and software. [http://cbig.it.helsinki.fi/files/Zonation/Zonation_manual_v4_0.pdf].
The Nature Conservancy. 2014. Secured Lands dataset. The Nature Conservancy, Eastern Conservation Science. Boston, MA. [http://www.conservationgateway.org/ConservationByGeography/NorthAmerica/UnitedStates/edc/reportsdata/terrestrial/secured/Pages/default.aspx].
White, T.H., JR., J.L. Bowman, B.D. Leopold, H.A. Jacobson, W.P. Smith, and F.J. Vilella. 2000. Influence of Mississippi alluvial valley rivers on black bear movements and dispersal: Implications for Louisiana black bear recovery. Biological Conservation 95:323–331.