(CRAM) For Wetlands User's Manual Version 5.0.2

California Rapid Assessment Method for Wetlands v. 5.0.2 – Chapter 3
For air photos and other imagery, the minimum pixel resolution is 3m (i.e., each pixel in the
digital image of a site should represent no more than about 9m 2 of area). Existing Digital
Orthogonal Quarterly Quadrangles (DOQQs) dating from 1998 to 2004 with a pixel resolution
of 3m, and geo-rectified natural color imagery dated 2005 with a pixel resolution of 1m are
available from the National Agriculture Imagery Program (NAIP) for the entire state. The
eCRAM software is designed to work with any geo-rectified imagery that can be loaded into the
image directory and then used with a tablet computer or laptop in the field to map AAs and to
conduct the assessment using CRAM.
3.7 Step 7: Conduct Field Assessment of Condition Metrics and Stressors
After assembling the background information about the wetland to be assessed, the next step is
to conduct an assessment of the wetland in the field. A complete description of CRAM metrics
and the Stressor Checklist is provided in Chapter 4. Fieldwork for CRAM consists of finding
and confirming the boundaries of the AA, and scoring the AA based on the condition metrics
and stressor checklist. Any field-based modifications of the preliminary AA boundary must be
recorded on the site imagery.
3.8 Step 8: Complete CRAM Scores and Basic QA/QC Procedures
3.8.1 Calculating CRAM Scores
Scores for CRAM are easily calculated. There is no weighting of any metrics or attributes.
Weightings are not supported by theory or the validation exercises. Letter scores for each metric
(A, B, C, D) are simply converted into whole integer scores (12, 9, 6, 3, respectively; see Step 1 in
Table 3.11).
For the Hydrology and Physical Structure attributes, the attribute scores are simply calculated as
the sum of the component metric scores (see Step 2 in Table 3.11).
For the Buffer and Landscape Context attribute, the submetric scores relating to buffer are
combined into an overall buffer score that is added to the score for the Landscape Connectivity
metric, using the formula in Step 2 in Table 3.11.
For the Biotic Structure attribute, the Plant Community metric consists of three submetrics
(Number of Plant Layers Present; Number of Co-dominant Species; and Percent Invasion).
Prior to calculating the Biotic Structure attribute score, the values for these submetrics must be
averaged. Then the Biotic Structure attribute score can be calculated as described in Table 3.11.
Each raw attribute score is then converted into a percentage of the maximum possible score (see
Step 3 in Table 3.11). This eliminates any weighting of one attribute relative to another due to
their differences in numbers of component metrics and numbers of alternative states of the
metrics.
An overall AA score is calculated by averaging the attribute scores. All scores are rounded to the
nearest whole percentage value (see Step 4 in Table 3.11).
Different wetlands are likely to have different functions and ecological services due to
differences in wetland form, structure, geomorphic setting, climatic regime, evolutionary stage,
stressor regime, etc. It is therefore unlikely that the same CRAM score represents the same level
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