Vegetation inventory, mapping and characterization re-port, Saguaro National Park: Volume I, main report

Galvin, Jeff; Studd, Sarah

doi:10.36967/nrr-2284709

The Sonoran Desert Network (SODN) conducted a vegetation mapping and characterization effort at Saguaro National Park from 2010 to 2018. This project was completed under the National Park Service (NPS) Vegetation Mapping Inventory, which aims to complete baseline mapping and classification inventories at more than 270 NPS units. The vegetation map data were collected to provide park managers with a digital map product that meets national standards of spatial and thematic accuracy, while also placing the vegetation into a regional and national context. The data standard was designed to facilitate the production of uniform statistics about vegetation across the nation, enable the translation of data collected at various scales, and allow data sharing, aggregation, and comparison across regions. Saguaro National Park consists of two units located at opposite ends of Tucson, Arizona. The Tucson Mountain District (TMD) spans the Tucson Mountains to the west of Tucson, while the Rincon Mountain District (RMD) spans the Rincon and Tanque Verde Mountains to the east. These units were completed as separate projects due to their large size and considerable differences in vegetation communities, elevational range, and geology. This report combines the projects from both units into one cohesive document. Vegetation mapping and characterization comprised four major phases: (1) field-based data collection, (2) development of vegetation community types at the National Vegetation Classification (NVC) association level, (3) development of the vegetation map, and (4) accuracy assessment of the vegetation map. These phases began at the TMD in spring 2010 and at the RMD in spring 2013. The final phase, accuracy assessment, was completed at the TMD in fall 2016 and at the RMD in summer/fall 2018. Due to concurrent vegetation projects at other SODN parks, fieldwork at both units was sporadic throughout these time periods. Further detail can be found in the sections of this report detailing field effort. A total of 97 distinct vegetation communities were described: 9 exclusively at the TMD, 83 exclusively at the RMD, and 5 occurring in both districts. These communities ranged from low-elevation creosote (Larrea tridentata) shrublands spanning broad alluvial fans to mountaintop Douglas fir (Pseudotsuga menziesii) forests on the slopes of Rincon Peak. All 97 com-munities were described at the association level, each with detailed narratives including lists of species found in each association, their abundance, landscape features, and overall com-munity structural characteristics. These associations were attributed across 76 map classes in the final map: 13 at the TMD and 68 at the RMD (with 5 occurring at both districts). The final project phase of accuracy assessment showed overall map accuracy for all classes was 78.4% (90% CI: 74.0, 83.0) at the TMD, and 76.3% (90% CI: 74.0, 79.0) at the RMD. Individual per-class accuracies ranged from 41.4% to 100%. Only 15 of the 97 vegetation types were existing “accepted” types within the NVC. The others are newly described and specific to Saguaro National Park (and will be proposed for formal status within the NVC). The products are designed with the goal of facilitating ecologically-based natural resources management and research. The vector (polygon) map is in digital format within a geodata-base structure that allows for complex relationships to be established between spatial and tabular data, and allows much of the data to be accessed concurrently. Each map unit has multiple photo attachments viewable easily from within the geodatabase, linked to their actual location on the ground. The Geographic Information System (GIS) format of the map allows user flexibility and will also enable updates to be made as new information becomes available (such as revised NVC codes or vegetation type names) or in the event of major disturbance events that could impact the vegetation.

Vegetation inventory, mapping and characterization re-port, Saguaro National Park: Volume I, main report

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