The objectives of the overview assessment are:
to identify within the previously logged riparian areas,
areas with known or suspected impaired functions
to identify sites for Level 1 field assessment.
The overview assessment uses existing or easily obtained
information to provide a preliminary indication of impaired
riparian function at specific sites in the watershed. The
results of the overview assessment will direct subsequent
field surveys to those areas of the watershed where riparian
function impairment may require restoration. If location
of sites and extent of impairment are already known, you
may be able to proceed very quickly to Level 1 field surveys
after summarizing the existing data. Most overview assessments
should only require from 2 to 10 person-days of effort, depending
on the extent of area to be covered.
Note that the results of the initial watershed assessment
procedure, the channel conditions and prescriptions assessment
procedure (Technical Circular No. 7) and the fish habitat
assessment procedure (Technical Circular No. 8), if already
completed, may help identify areas of special concern in
advance of the overview RAPP.
Steps in the Overview Assessment
The steps in the overview assessment are:
Identify and delineate the watershed of interest.
Assemble existing information. Materials to review include
a combination of:
air photos (historic)
air photos, (recent), preferably low level 1:5000 scale and
in colour, especially where access is limited
licensee files, forest cover and TRIM maps
other MOF maps/reports, opening files
other WRP reports
interviews with local MOF and MELP personnel, forest licensee
From the existing information, following the instructions
for Form 1 (Appendix 7
Identify harvested areas, with primary focus being
harvested areas near or adjacent to S1-S3 streams,
otherwise by the contracting agency.
Categorize harvested areas by distinct riparian vegetation
types, which at the overview stage will be based
on stand structural stage and tree type (e.g., PSc,
pole sapling -
coniferous; MFm, mature forest-mixed conifer/deciduous;
SH, shrub-herb) (also refer to glossary). Dominant
be added if the data are available, but this will
seldom occur at the overview stage.
Record past harvesting and restocking history and
any other readily known or observable disturbances
(e.g., erosion and
Identify priority sites for Level 1 field assessment.
Use the following instructions to complete Form
1 (also refer to completed form example in Appendix
Watershed Name/Code: Identify the watershed by its gazetted
name and hierarchical watershed code. Refer to the Gazetteer
of Canada for British Columbia (Anonymous 1985) for official
names. Obtain the watershed code from the MELP Watershed
Dictionary (consult regional WRP staff). Note that sub-basins
may have their own codes. If standard watershed codes have
not been assigned to the stream, follow the guidelines in
Identification Guidebook to assign an interim
locational point to the stream mouth.
NTS Map: Record index number of the NTS (1:50 000 scale)
or BC Geographic Survey (BCGS 1:20 000 scale) map that depicts
the downstream boundary of the stream reach or sampling site.
Air Photo: Record the flightline and air photo number that
depicts the stream reach or sampling site.
Reach # (Reach number): A reach is a relatively homogeneous
section of stream having a repetitious sequence of physical
characteristics and habitat types. Reach numbers are assigned
in upstream ascending order starting from the mouth of the
stream. Delineating reaches is optional if doing only a riparian
assessment, but is strongly recommended if also completing
a channel condition, or fish habitat assessment (WRP Tech.
Circs. 7 and 8, respectively).
Polygon # (Polygon number): A polygon is an area of vegetation
that appears on air photos to be distinct from the adjacent
vegetation. Using an omnichrome pen and mylar overlay, draw
the boundaries of each polygon in the riparian zone of your
Stand Structure: Identify and record the stand structure
(SSt) within each polygon. Classification should include
one of the following (see Glossary for more details):
INIT (initial succession) - earliest successional (developmental)
stage (0-1 yr)
SH (shrub herb) - early successional stage (1-20 yr)
PS (pole sapling) - trees >10
m tall, densely stocked (10-40 yr, depending on species
(e.g., alder is PS stage
at 10-15 yr)
YF (young forest) - forest canopy forms distinct layers
MF (mature forest) - Canopy comprised of
mature trees with second cycle of shade-tolerant trees establishing
OF (old forest) - old, structurally complex stands of mainly
shade tolerant and regenerating trees (250+ yr).
If it is possible to pick out tree species and dominance
from air photos and/or forest cover maps, record these in
the same column. Otherwise, include only stand structure.
If only 1:15 000 to 1:20 000 air photos are available, it
may only be possible to identify stand structure and whether
it is deciduous tree dominated (d) (>75% tree cover);
coniferous tree dominated (c) (>75% tree cover); or mixed
(m) deciduous/coniferous tree species (neither deciduous
nor coniferous trees account for >75% cover) (e.g., PSc refers to a "conifer dominated pole-sapling stand).
Tentative RVT #: Based on stand structure as recorded in
the previous column, assign a riparian vegetation type (RVT)
number for each polygon, keeping in mind that several different
polygons may contain the same RVT. At this time, the RVT
numbers are tentative since they will likely be adjusted
during the field visit at the Level 1 assessment, with the
final RVT labels recorded on Form 3 (the Level 1 assessment
summary form). The final RVT labels will be based on stand
structure and tree species, and may also include a recognition
of understorey vegetation types. One would also expect different
RVT numbers in different BEC zones and subzones. The Overview
stage, being an office-based assessment can only provide
a broad-brush RVT description.
Stream Class: Identify the stream class (Code S1-S6 stream).
A key to the riparian classification of streams was shown
previously in Table 1.
Harvesting History: Using sources such as forest cover maps,
silvicultural history (ISIS database from MOF), and local
knowledge, record known harvesting history such as harvest
date, age class, silviculture treatments, and year of site
preparation or replanting.
Other Disturbances: If a major disturbance other than harvesting
has occurred, record it. Disturbances include fire, insect
or disease infestation, flooding, surface erosion, slope
failure, overgrazing and presence of roads, bridges and culverts.
Priority for Level 1: Selection of sites recommended to
proceed to a Level 1 field visit and assessment should be
based on the following:
information gathered on stand structure, harvest history
and extent of proper functioning condition (Figure
other disturbances (e.g., fire, erosion, wind throw)
high fisheries values
expected level of benefit to the watershed, and likelihood
of restoration success.
Output from the Overview Assessment
Output from the overview assessment includes the following:
Brief discussion of methods used in the overview assessment.
Mapping and map overlays of harvested riparian polygons in
Identification of known or suspected impaired polygons.
A brief discussion of potential impairments.
Recommended sites for Level 1 field data collection.
In some cases, a recommendation for no further assessment
may be made based on, for example, knowledge that sufficient
regeneration is already occurring. However, confirmation
of this would likely require a brief field reconnaissance
by an experienced riparian vegetation specialist.
Figure 3. Stand structure stages on pathway
to desired future condition.