The Sacramento River vegetation map was validated over the summer (June-September) of 2008. Field validation of CSUC polygons was conducted along the 100 mile stretch between Red Bluff (south of the diversion dam) and Colusa on over 30 properties owned by the Department of Fish and Game, The Nature Conservancy, Fish and Wildlife Service, and the Department of Water Resources. Polygon accuracy was checked visually by editing polygon attributes in ArcPad 7.1 loaded into Trimble GeoXM units, via rapid assessments, intensive modified Whittaker plots, re-digitizing 500m by 500m blocks of vegetation, input from other project collaborators, and by revisiting and referencing Vaghti (Vaghti 2003) relevé plots. Data analysis was conducted in JMP IN 7.

Rapid Assessments

Rapid assessments were collected along 100 miles of the Sacramento River between Red Bluff and Colusa. We used the CNPS protocol as outlined in the Vegetation Rapid Assessment Protocol created by the CNPS Vegetation Committee (http://cnps.org/cnps/vegetation/). RA’s were then used to validate the CSU Chico map and will be turned into the DFG vegetation program.

Intensive Sampling

Intensive modified Whittaker plots were set up throughout the project area, a 100 mile stretch of the Sacramento River from Red Bluff to Colusa. These plots were set up in areas that were floristically representative of a particular vegetation type at the association level. Data collection was conducted based on procedures developed by Barnett and Stohlgren (2003).

Visual Field Validation

Field validation of CSUC polygons was conducted along a 100 mile stretch of the Sacramento River between Red Bluff (south of the diversion dam) and Colusa on over 30 properties owned by the Department of Fish and Game, The Nature Conservancy, Fish and Wildlife Service, and the Department of Water Resources. Polygon accuracy was checked visually in the field by species dominance and then editing polygon attributes in ArcPad 7.1 loaded into Trimble GeoXM units.

Digital Map Check

Using ArcGIS9.2, we created 500m x 500m blocks that cover the study area. Blocks overlapping > 33.4% of the 2007 Riparian Map were selected at random for re-digitization. GIS Technicians, after a period of training and cross-calibration, digitized vegetative cover with each selected block using the 2007 aerial photos as reference for interpretation. In all, X blocks were re-digitized for (see map above) for statistical analysis. Statistical analyses consisted of paired comparisons, first for inter-rater reliability, and second for vegetation class representation.