San Juan Island National Historical Park Vegetation Mapping Project - Spatial Vegetation Data
Vegetation Inventory
Dates
Publication Date
2012-01-01
Time Period
2012-01-01
Summary
The National Park Service (NPS) Vegetation Inventory Program (VIP) is an effort to classify, describe, and map existing vegetation of national park units as part of generating baseline data products for the NPS Natural Resources Inventory and Monitoring Program. Plot data were collected during field visits to SAJH during the summer of 2010 and spring of 2011. Vegetation polygons were initially developed using aerial photography within ArcGIS. These polygons were modified based on field work conducted during the summer of 2010 and spring of 2011. The small extent of the park allowed classification data collection to occur simultaneously with field-based mapping. Prior to conducting field visits, existing vegetation maps, soils maps, [...]
Summary
The National Park Service (NPS) Vegetation Inventory Program (VIP) is an effort to classify, describe, and map existing vegetation of national park units as part of generating baseline data products for the NPS Natural Resources Inventory and Monitoring Program. Plot data were collected during field visits to SAJH during the summer of 2010 and spring of 2011. Vegetation polygons were initially developed using aerial photography within ArcGIS. These polygons were modified based on field work conducted during the summer of 2010 and spring of 2011. The small extent of the park allowed classification data collection to occur simultaneously with field-based mapping. Prior to conducting field visits, existing vegetation maps, soils maps, wetland locations, and 2008 NAIP 6-inch color orthophotos were used to delineate preliminary polygons using ArcGIS 9.3.1. Each polygon was assigned a "GIS_Poly" code. Some areas were difficult to map without field verification. Hardcopy maps of the preliminary polygons were produced using ArcGIS at 1:2600 scale for non-forested vegetation and 1:1900 scale for forested vegetation. The maps were used to delineate boundaries of vegetation types in the field. As vegetation types were mapped, they were assigned to previously defined associations and plots not falling within the variation of existing types were used to define new classification units when appropriate. Each polygon was initially typed using one of the following keys: (1) Plant Associations of Balds and Bluffs of Western Washington (Chappell 2006a) and (2) Upland Plant Associations of the Puget Trough Ecoregion, Washington (Chappell 2006b). Each polygon was assigned a "Field_Poly" identifier as a quick way to code vegetation types (The cross-walk between "GIS_Poly" and "Field_Poly" is found in the Microsoft Excel classification spreadsheet that accompanies this report.) The majority of native (not ruderal) forest and native grassland vegetation types encountered in the park were successfully keyed using these two resources. The Washington Natural Heritage Program (WNHP) state vegetation classification was reviewed for possible matches for types not identifiable using the Chappell (2006a,b) keys. The WNHP classification includes citations of all plant associations described in Washington. If no applicable association was identified in the Chappell (2006a,b) keys or the WNHP classification, then a classification or observation plot was established and, based on tabular analysis of these data, a new type was recommended. When necessary, polygons were redrawn in the field on the hardcopy maps to more accurately reflect vegetative patterns. Modified polygon boundaries were then edited back in the office with ArcGIS resulting in a vegetation map.
