Caribbean Karst Habitat (Southeast Blueprint Indicator)

Reason for Selection “Karst is a type of landscape where the dissolving of the bedrock has created sinkholes, sinking streams, caves, springs, and other characteristic features. Karst is associated with soluble rock types such as limestone, marble, and gypsum. In general, a typical karst landscape forms when much of the water falling on the surface interacts with and enters the subsurface through cracks, fractures, and holes that have been dissolved into the bedrock. After traveling underground, sometimes for long distances, this water is then discharged from springs, many of which are cave entrances” (NPS 2022). The Caribbean region has one of the most significant karst landscapes in the world and is recognized by the International Union for Conservation of Nature (IUCN) World Commission of Protected Areas as in need of protection (Day 2010). In Puerto Rico, the unique karst landscape provides habitat for many endemic and rare species, such as the Puerto Rican boa, the Puerto Rican skink, Puerto Rican sharp-shinned hawk, and many federally listed plants (Lugo et al. 2001). In addition, the Puerto Rico karst belt contains the island’s largest mature forests, coastal wetlands, estuaries, and underground cave systems. The northern limestone region supplies 22% of Puerto Rico’s public drinking water (Lugo et al. 2001). On St. Croix, the karst landscape supports the largest aquifer in the U.S. Virgin Islands, which covers approximately 25 mi2 and produces about 67% of the total groundwater withdrawn in the U.S. Virgin Islands (Zack 1986; Dr. Olassee Davis - Ecologist and Extension Specialist with the University of the Virgin Islands, personal communication, July 6, 2023). Caribbean karst is also an important cultural landscape. For example, caves served as refuges for Maroons during colonization (Day 2010). Cave systems within this landscape also provide opportunities for low-impact nature-based tourism (Hall 2014). Input Data * [Southeast Blueprint 2023 subregions]: Caribbean * [Southeast Blueprint 2023 extent] * 2020 [LANDFIRE Existing Vegetation Type] (EVT) (v2.2.0) for Puerto Rico and the U.S. Virgin Islands; [access the data for U.S. Insular Areas] * U.S. Geological Survey [Karst in the United States: A digital map compilation and database], last modified 8-1-2014, accessed 5-18-2023 * National Park Service [Digital Geologic Map of St. Croix and Buck Island Reef National Monument, U.S. Virgin Islands] (published 4-28-2008), accessed 6-22-2023 * Puerto Rico Karst Restricted Zone shapefile, shared on 6-15-2023 by Rossana Vidal Rodriguez with the Puerto Rico Department of Natural and Environmental Resources (PR DNER) ([rvidal@drna.pr.gov]) This is an improved version of the Karst Conservation Zone layer (also known as “zona_amortiguamiento_carso” layer) found in the [2018 Puerto Rico Natural Areas database]. The Karst Conservation Zone layer is a 50 m buffer around the Karst Restricted Zone. The delimitation of the Karst Restricted Zone originated from the [PR DNER’s 2008 Study of Karst] . Mapping Steps * Create a karst shapefile for St. Thomas and St. John by selecting all features in the USGS Karst file VIcarbonates.shp except where UNIT_NAME = ‘Kingshill Marl’. That geologic unit appears in St. Croix and we exclude it because we have better data for St. Croix from the National Park Service. * Create a karst shapefile for St. Croix from the National Park Service St. Croix geology map by selecting GLG_SYM = ‘Mikh’ from buisglg.shp. MIkh is the code for Kingshill Marl. * Merge the karst shapefiles created for St. John, St. Thomas, and St. Croix with the Puerto Rico Karst Restricted Zone and Karst Conservation Zone buffer shapefiles, then convert to raster. This creates a combined karst layer for the U.S. Virgin Islands and Puerto Rico. * Reclassify the LANDFIRE EVT data into 3 alteration classes where 3 is natural, 2 is altered, and 1 is heavily altered. Assign a value of 1 to all pixels with a value in the EVT_NAME field of “Developed-High Intensity” or “Developed-Medium Intensity”. Assign a value of 2 to all pixels with a value in the EVT_LF field of “Developed”, “Agriculture”, or “Barren”, or a value in the EVT_NAME field of “Agriculture-Pasture and Hay” or “Caribbean Bush fruit and berries”. Assign a value of 3 to everything else. Classify pixels with a value in the EVT_NAME field of “Open Water” as NoData. Note: The Caribbean bush fruit and berries LANDFIRE class is intended to represent sun-grown coffee, while tropical agroforestry plantation is intended to capture shade-grown coffee (LANDFIRE help desk, personal communication, 2-22-23). As a result, we considered Caribbean bush fruit and berries to be in the middle alteration class and considered tropical agroforestry plantation to be natural for the purposes of this indicator. * Combine the karst raster with the reclassified LANDFIRE EVT data to produce the final indicator values shown below. * Clip to the Caribbean Blueprint 2023 subregion. * As a final step, clip to the spatial extent of Southeast Blueprint 2023. Note: For more details on the mapping steps, code used to create this layer is available [in the Southeast Blueprint 2025 Data Download] or [Caribbean-only Southeast Blueprint 2025 Data Download] under > 6_Code. Final indicator values Indicator values are assigned as follows: 3 = Karst with natural landcover 2 = Karst with pasture, crops, or open space in developed area 1 = Karst with developed landcover 0 = Not identified as karst Known Issues * Some karst areas are underprioritized in Puerto Rico because they are not included in the Karst Restricted Zone. While the Karst Restricted Zone focuses on the most sensitive karst areas, it does not include all karst on the island. * Some areas are both under- and overprioritized in St. Thomas. The USGS karst data are not as fine-resolution as other data in this indicator and are likely under- and overpredicting karst in areas along the boundary of the polygons used. * This indicator likely misses some karst areas in the U.S. Caribbean that are not captured in the input datasets. Disclaimer: Comparing with Older Indicator Versions There are numerous problems with using Southeast Blueprint indicators for change analysis. Please consult Blueprint staff if you would like to do this (email [hilary_morris@fws.gov]). Literature Cited Day, Mick. 2010. Human Interaction with Caribbean Karst Landscapes: Past, Present and Future. Acta Carsologica. 39. 137-146. 10.3986/ac.v39i1.119. Accessed June 27, 2023. [[https://ojs.zrc-sazu.si/carsologica/article/view/119/109]]. Department of Nature and Environment Resources (DNER). 2009. Declaración de evaluación de impacto ambiental estratégica. Estudio del carso. (trans. Strategic Environmental Impact Statement. Study of Karst.) [[https://www.drna.pr.gov/historico/oficinas/saux/secretaria-auxiliar-de-planificacion-integral/carso/DIA-E_estudio_carso.pdf]]. Hall, A., and Day, M., Ecotourism in the state forest karst of Puerto Rico. April 2014. Journal of Cave and Karst Studies, v. 76, no. 1, p. 30–41. DOI: 10.4311/2011SS0263 [[https://legacy.caves.org/pub/journal/PDF/v76/cave-76-01-30r.pdf]]. LANDFIRE, Earth Resources Observation and Science Center (EROS), U.S. Geological Survey. Published August 1, 2022. LANDFIRE 2020 Existing Vegetation Type (EVT) Puerto Rico US Virgin Islands. LF 2020, raster digital data. Sioux Falls, SD. [[https://www.landfire.gov]]. Lugo, Ariel E.; Castro, Leopoldo Miranda; Vale, Abel; López, Tania del Mar; Prieto, Enrique Hernández; Martinó, Andrés García; Rolón, Alberto R. Puente; Tossas, Adrianne G.; McFarlane, Donald A.; Miller, Tom; Rodríguez, Armando; Lundberg, Joyce; Thomlinson, John; Colón, José ; Schellekens, Johannes H.; Ramos, Olga; Helmer, Eileen. 2001. Puerto Rican Karst-A Vital Resource. United States Department of Agriculture Forest Service Gen. Tech. Report WO-65. [[https://doi.org/10.2737/WO-GTR-65]]. National Park Service. Karst Landscapes. Last updated April 27, 2022. Accessed August 16, 2023. [[https://www.nps.gov/subjects/caves/karst-landscapes.htm]]. Protected Areas Conservation Action Team. 2018. Puerto Rico Protected Areas Database. December 2018 version. GIS data. San Juan, PR. [[https://research.fs.usda.gov/iitf/products/dataandtools/puerto-rico-protected-natural-areas-2018]]. Weary, D.J., and Doctor, D.H., Karst in the United States of America: a digital map compilation and database: U.S. Geological Survey Open-file Report 2014-1156. [[https://pubs.usgs.gov/of/2014/1156/]]. Zack, Allen, Rodriques-Alonso, Teresita, and Roman-Mas, Angel. 1986. U.S. Virgin Islands Ground-water Quality report. U.S. Geological Survey Open-File Report 87-0756. [[https://pubs.usgs.gov/of/1987/0756/report.pdf]].