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

California Rapid Assessment Method for Wetlands v. 5.0.2 – Chapter 5
CHAPTER 5:
GUIDELINES TO COMPLETE STRESSOR CHECKLISTS
A. Definition: For the purposes of CRAM, a stressor is an anthropogenic perturbation within a
wetland or its setting that is likely to negatively impact the functional capacity of a CRAM
Assessment Area (AA). In contrast, disturbances are distinctly defined as natural phenomena,
although they might have similar impacts as stressors.
B. Rationale: Physical and biological processes connect wetlands to their environmental
settings and thus help shape wetland conditions, which are therefore influenced by land use
practices within the settings (Frissell et al. 1986, Roth et al. 1996, Scott et al. 2002). Wetland
conditions can also be affected by stressors operating directly within the wetlands, although
these tend to be less abundant than stressors originating in the surrounding landscape.
The purpose of the Stressor Checklist is to identify stressors within a CRAM Assessment Area
(AA) or its immediate hat might help account for any low CRAM scores. In some cases, a single
stressor might be the primary cause for low-scoring conditions, but conditions are usually due to
interactions among multiple stressors (USEPA 2002).
There are four underlying assumptions of the Stressor Checklist: (1) stressors can help explain
CRAM scores; (2) wetland condition declines as the number of stressors acting on the wetland
increases (there is no assumption that the decline is additive (linear), non-linear, or
multiplicative); (3) increasing the intensity or the proximity of the stressor results in a greater
decline in condition; and (4) continuous or chronic stress increases the decline in condition.
C. Seasonality: The Stressor Checklist is not sensitive to seasonality.
D. Office and Field Indicators: The process to identify stressors is the same for all wetland
types. For each CRAM attribute, a variety of possible stressors are listed. Their presence and
likelihood of significantly affecting the AA are recorded in the Stressor Checklist Worksheet.
For the Hydrology, Physical Structure, and Biotic Structure attributes, the focus is on stressors
operating within the AA or within 50 m of the AA. For the Buffer and Landscape Context
attribute, the focus is on stressors operating within 500 m of the AA. More distant stressors that
have obvious, direct, controlling influences on the AA can also be noted.
Table 5.1: Wetland disturbances and conversions.
Is there evidence of a major disturbance
flood fire landslide other none
(select one best answer)
If there is evidence of disturbance, how
severe was it
If the wetland has been
converted from another
type, what type was it
not
converted
effects will last
next 5 years
effects will last
3-5 years
effects will last
1-2 years
depressional vernal pool
vernal pool
system
non-confined
riverine
confined
riverine
seasonal
estuarine
perennial saline
estuarine
perennial nonsaline
estuarine
wet meadow
lacustrine seep or spring playa
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