California Rapid Assessment Method for Wetlands - State Water ...

California Rapid Assessment Method for Wetlands v. 5.0.2 – Chapter 2
2.3 Developmental Framework
The CRAM developmental process consists of nine steps with distinct products organized into
three phases: basic design, calibration, and validation (Table 2.1).
Core Team
Core and
Regional
Teams
Table 2.1: Basic outline of CRAM development.
Basic
Design
Phase
Calibration
Phase
Validation
Phase
Develop conceptual models of wetland form and function
Identify universal Attributes of wetland condition
Nominate Metrics of the Attributes
Nominate descriptions of alternative states for each Metric
Clarify and revise the Metrics and narrative descriptions of
alternative states based on regional team input and inter- and
intra-team comparisons
Develop a checklist to identify stressors
Test and select methods of scaling and weighting Attributes
and Metrics
Test and select formulas for calculating Attribute scores and
AA scores
Validate Metrics and Attributes using Level 3 data
Conduct independent peer review
Provide outreach and training
2.3.1 Basic Design
This phase of CRAM development involved creating conceptual models of wetland form and
function, defining key terms, developing the wetland typology, identifying the attributes, and
formulating metrics that describe each attribute. The basic design work was done primarily
through initial field-testing and feedback by Regional Teams and the Core Team. Version 2.0 of
CRAM marked the completion of the basic design phase.
Each CRAM attribute is represented by a set of metrics (Table 2.2 below), and each metric is
represented by a set of mutually exclusive narrative descriptions of alternative states. In
aggregate, the alternative states of all the metrics for any type of wetland represent its full range
of visible form and structure.
An effort was made to separate assessments of condition from assessments of stress. This was
done to explore correlations between stress and condition. For example, CRAM AAs can be
grouped according to their associated stressors, and the groups can be compared based on their
CRAM scores. The separation has been difficult to achieve, however, For example, the Plant
Community metric of the Biotic Structure attribute includes a sub-metric about the relative
abundance of non-native plant species, although biological invasion is usually considered a
significant stressor. Some autocorrelation can therefore be expected between stress and
condition as assessed using the current version of CRAM
2.3.2 Calibration
The calibration phase was used to determine if the draft wetland classification scheme, the
attributes, the metrics, and the narrative descriptions of alternative states were (1) clear and
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