Site Analysis - Project Planning and Management for Ecological Restoration - page 54

soil types that are 2:1 or steeper present conditions that are ripe for surface erosion, and some re-
gime must be developed in the first phase of your plans to address it. Steep slopes, especially man-
ufactured slopes, are sometimes referred to as “critical areas of concern” and could undermine the
success of your project if not modified through various mechanical techniques, such as ripping.
Elevation. Are there freeze lines or frost pockets that will affect the growth rate or growing habit
of certain target species? Is the elevation beyond that known for the species being considered for
the site? Canyons and ravines typically support species that thrive in moister and cooler conditions.
Microtopographic variations may be a consideration when working in marshes and tidelands. Sub-
tle changes of just a few centimeters can affect the success or failure of certain intertidal species.
Conventional land surveyors may overlook these minute variations in landform. Make sure that
the land surveyor understands your requirements.
Geology. Depth to bedrock, location of rock outcrops, and occurrence of certain formations
may restrict using the site as desired. The occurrence of harmful elements or materials could
conflict with your restoration or harm your targeted plant species. Some plant communities are
restricted to growing only on soils derived from specific geologic formations (e.g., soils derived
from serpentine formations).
Soils. You should determine the depth and texture of the soils at various locations throughout
the site. Soil texture affects permeability, root penetration, water and nutrient holding capacity,
shrink swell potential, and erodibility. Before conducting fieldwork, locate soil maps and reports
that may have been made by either the NRCS (previously known as Soil Conservation Service), a
local agricultural agency, or the previous or current landowner. Soil maps will frequently provide
the information needed to make decisions. The reports containing these maps provide exten-
sive information that may have significant value in your planning process. Information frequently
found in these reports includes soil texture, general description of the soil, typical depth from
surface, types of vegetation naturally occurring on soils, drainage characteristics, suitability for
specific agricultural crops, depth to hard rock or hardpan, and erodibility. Locations in your region
are identified with specific data on permeability and available water capacity of the soil as well as
pH. Keep in mind that these data are intended to give a general idea of the soils in your area.
March and Smith (2011) used ecological site data associated with NRCS digital soil type maps
in conjunction with elevation data to create potential vegetation assemblage maps. These maps
were used to guide the selection of the appropriate restoration target. If you lack soil maps, we
strongly recommend sampling to assess the differences in soil material throughout your site. Al-
ways conduct a field site investigation to check the maps with the site to verify that the landform
has not been modified. Methodically plot these locations on a scaled plot map. Identify any lo-
cations where the soil appears degraded, whether by salts, chemicals, oils, or so forth. Obtain soil
samples near water bodies and from any locations previously identified as areas of concern, as well
as wherever you notice changes in vegetation structure or elevation.
How many samples should you collect? Here, common sense and input from the information
already collected will guide your decision. If you know that some areas represent disturbed or
modified topography, more extensive sampling in those areas may be needed. Areas with no ap-
parent modifications would receive less intense study. If soil maps generated by the government or