(CRAM) For Wetlands User's Manual Version 5.0.2

4.0 Summary
California Rapid Assessment Method for Wetlands v. 5.0.2 – Chapter 4
CHAPTER 4:
GUIDELINES FOR SCORING CRAM METRICS
This chapter contains detailed guidelines for using CRAM. Each metric is supported by a
definition, rationale, and an indication of the metric’s sensitivity to seasonal variability in wetland
condition. Also provided are visual cues or indicators of condition that can be used in the field
or when studying the imagery of a site to guide the scoring of the metrics.
The attributes and stressor checklists are the same for all wetland types and regions of the State.
The wetland types are very different from each other, however, in terms of their form and
structure. Some metrics have been adjusted to reflect these differences. There is not enough
evidence at this time to warrant adjusting any metric for regional differences in any wetland type.
A full set of data sheets and worksheets for each wetland type is provided on the CRAM website
(www.cramwetlands.org) as a basic hardcopy field book for conducting CRAM assessments.
CRAM training materials are also available at the CRAM web site (www.cramwetlands.org).
4.1 Attribute 1: Buffer and Landscape Context
For the purposes of CRAM, a buffer is a zone of transition between the immediate margins of a
wetland and its surrounding environment that is likely to help protect the wetland from
anthropogenic stress (see Figure 2.2). Areas adjoining wetlands that probably do not provide
protection are not considered buffers.
Buffers can protect wetlands by filtering pollutants, providing refuge for wetland wildlife during
times of high water levels, acting as barriers to disruptive incursions by people and pets into
wetlands, and moderating predation by ground-dwelling terrestrial predators. Buffers can also
reduce the risk of invasion by non-native plants and animals, by either obstructing terrestrial
corridors of invasion or by helping to maintain the integrity and therefore the resistance of
wetland communities to invasions.
Because regulation and protection of wetlands historically did not extend to adjacent uplands,
these areas in some cases have been converted to recreational, agricultural, or other human land
uses and might no longer provide their critical buffer functions for wetlands.
CRAM includes two metrics to assess the Buffer and Landscape Context attribute of wetlands:
the Landscape Connectivity metric and the Buffer metric. The buffer metric is composed of
three submetrics: (1) percentage of the AA perimeter that has a buffer; (2) the average buffer
width; and (3) the condition or quality of the buffer.
4.1.1 Landscape Connectivity
A. Definition: The landscape connectivity of an Assessment Area is assessed in terms of its
spatial association with other areas of aquatic resources, such as other wetlands, lakes, streams,
etc. It is assumed that wetlands close to each other have a greater potential to interact
ecologically and hydrologically, and that such interactions are generally beneficial.
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