Sand Creek Massacre National Historic Site Vegetation Classification and Mapping, A report for the Southern Plains Network

Colorado Natural Heritage Program; Fink, Michelle; Neid, Stephanie; Stephens, Joe; Forest, Kelsey

Sand Creek Massacre National Historic Site (SAND) is on the high plains of southeasternColorado in the rain shadow of the Rocky Mountains. It is in north-central Kiowa County,approximately 25 miles from the state border with Kansas. The site occupies 12,500 acres thatare authorized by Congress to protect, interpret, memorialize, and commemorate the Sand CreekMassacre of November 29 and 30, 1864. Within the authorized boundary, 1555 acres have beenacquired and established. The site is currently not accessible or open to the public.SAND is roughly bisected by Big Sandy Creek, a sub-irrigated, intermittent stream typical of asandy Great Plains riparian system. Loamy, level plains of shortgrass prairie and agriculturalfields expand away from Big Sandy Creek to the north and east. Sandhills with sand sagebrushshrublands occupy the south and west side of Big Sandy Creek, much of which is in nativerangeland. The authorized boundary of SAND surrounding the established boundary is in privateownership, and it is surrounded by dryland agricultural fields and rangeland with sparsedevelopment.As a newly acquired parcel, National Park Service (NPS) Southern Plains Network initiated avegetation classification and mapping project as one of many on-going projects to gatherbaseline data to inform land management decisions and planning. Following the protocols of theUSGS – NPS Vegetation Mapping Program, the Colorado Natural Heritage Program (CNHP)performed a two-year project to classify and map the vegetation at SAND. The project wasinitiated in the spring of 2005 with a project planning meeting between CNHP, SAND biologists,and the NPS program botanist. Project planning and logistics were completed during the latespring of 2005, and vegetation data for classification and mapping were collected during latesummer of 2005. The vegetation classification, field key, and local plant association descriptionswere completed and written during the winter of 2005 - 2006. Accuracy assessment data werecollected over the summer of 2006 and assessment of the vegetation map accuracy wascompleted in the winter of 2006.CNHP established 31 vegetation plots and 48 additional data collection points within theestablished SAND boundary to classify and map the vegetation within the authorized SANDboundary. Multivariate ordination and clustering analyses were used to classify the vegetation.As a result, six plant associations of the National Vegetation Classification (NVC) wereidentified and locally described. To produce the vegetation map, both National AgricultureImagery Program 1:12,000-scale, true color, digital ortho-imagery acquired in 2006 and theUSDA-FSA-APFO Digital Ortho Mosaic for Kiowa County were used in conjunction with fielddata to identify vegetation signatures. Four additional non-natural mapping units were devisedfrom the plot and observation point data to complete the map. The accuracy of the map wastested using 134 accuracy assessment plots collected across the ten map classes within theestablished SAND boundary in 2006. After final revisions, the accuracy assessment revealed anoverall thematic accuracy of 94%.The vegetation map produced for this project provides baseline data for resource managementdecisions. However, it only reflects a snapshot in time. Plant communities are dynamic entitiesxithat can change given changes in environmental parameters. Current land use, such as grazing management and water withdrawal from the Big Sandy Creek aquifers, will influence changes in vegetation over time. Monitoring these changes will facilitate adaptive management of park resources.

Sand Creek Massacre National Historic Site Vegetation Classification and Mapping, A report for the Southern Plains Network

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