The Field Survey: Inventory Methods and Features

This piece was originally published in Giving the Land a Voice: Mapping Our Home Places, edited by Sheila Harrington, LTA Land Trust Alliance of British Columbia, copyright 1999.

Human beings who are planning on living together in the same place will wish to include the non-human in their sense of community. This also is new, to say our community does not end at the human boundaries, we are in a community with certain trees, plants, birds, animals. The conversation is with the whole thing. That’s community political life.” – Gary Snyder – “Welcome Home”, New Catalyst 1986.

Now that you are familiar with the base map, you are ready to go out into the field and do a survey, discerning various habitats, other species who share the land and other biophysical features. Through the use of simple field survey methods, you will be able to assess the biophysical nature of a property. Thus you could protect sensitive areas, maintain habitat, gain a sustainable income from permaculture, repair soil depletion, reintroduce native species, or simply achieve awareness of the flows of life through a particular place.

Getting Started

This is the exciting part: gathering information for your map by exploring, observing and discovering your home place. This section provides simple procedures on how to gather the information. You will need a base map or aerial photo (large scale) of your home place to record field notes and observations. Our example is from a surveyor’s map of a lot showing the buildings in relation to the property lines.

Other tools you will need are a compass, tape measure, note book, field sheets and a camera could also be useful.

There are three methods of field survey you could undertake:

Ground truthing, which is done in conjunction with air photos, verifies boundaries and the composition of areas seen on the photo. The areas to be ground truthed vary according to the previous knowledge one has of the area.

Plots are sample sections representative of a larger area where all the measurements and observations are made. There can be several plots in a given area.

Transects are predetermined lines run across the land. They should cross a variety of edges or boundaries, and you could do one or several depending on the detail you want on the final map. Transects have a series of stations or stops which are based on pre-measured distances or natural boundaries. As with plots, if transects are marked by some permanent feature, it will be possible to do resurveys over the same line to detect changes over time.

We recommend that you use transects for conducting your field survey, as they are simple to do, require few tools, provide good information and are repeatable.

If you do not have a 100 to 200 metre measuring tape or hip chain, you can pace out the distances. To convert your steps to metres make the following calculation:

Measure 10 metres on the ground. Now walk that line counting the steps. Take comfortable steps that can be done no matter how steep the terrain might get. Walk this distance at least three times, counting the steps each time. Add those three numbers and divide by three. That value is the average number of steps it takes to walk 10 metres. Finally divide the 10 metres by the average number of steps. Use this factor to convert your paces on the transect to metre equivalents. For example, if your conversion factor was 86, that would mean that for every 100 paces you will have gone 86 X 100 = 86 metres.

You will need to find some feature or attribute to start your transect. This could be a large tree, a rock, a shoreline or even a human made object such as a utility pole. The important thing is to choose something that can be found easily again and is likely to be there for a long time. From this spot take a compass bearing for walking your transect.

The following series of maps will help you to visualize the transect and the type of information you would record. Take time to observe and record features and events. Enjoy!

Features You Can Survey

This section focuses on features you may wish to record for your area. the survey described in Chapter 3 only covered the outside boundaries of an area. This chapter details many other features you can survey, particularly soils, flora and fauna.

You don’t have to map everything at once. In order to include the full range of features found on a piece of land, it is necessary to do it in small, manageable steps. By taking your time, you will increase your awareness and appreciation of the subtleties of your home place. Also remember that your area changes with the four seasons. Get out, explore and record features during each season if possible.

You can prepare your own field sheet to assist in gathering observations on your survey. It is useful because it acts as a prompt to remind you of features to observe and record. A prototype is provided in the Appendix Section.

In addition, you could bring a sketch pad, drawing book or camera with you. On any particular day, you may sight something you cannot identify. Taking physical samples is risky when you do not know what something is; it may be a rare species which should be left in place.

With your fieldsheet, notebook and base map or air photo in hand, you are ready to start your survey. The following are suggested features to record for your map.

1a) Exposure

This refers to the direction or slope a piece of land faces. You assign this a compass direction by standing with your back to the slope and describing which direction the maximum exposure is found. If you are not on a slope, nearby landforms may also describe an exposure. The exposure is recorded as a general compass point using terms such as “southerly exposure” or “north facing.”

Knowing the exposure gives you an indirect evaluation of very important microclimate features of your land. In British Columbia, south facing slopes are generally warmer and drier; they are the first to lose their snow and so represent important winter feeding areas for deer. These slopes often support Garry oak meadow and grassland habitats. On the other hand, north facing slopes tend to be moister and cooler, holding snow longer, so they support a different mix of mosses and shrubs. Cedar and hemlock trees grow well on these slopes.

1b) Slope position

Most land has depressions, hills and relatively flat areas, and thus contains varying slope positions. These are generally relative to the movement of water on the site. The table and accompanying diagram will help you with this assessment.

Table 1
Diagram 1

The slope table above gives additional information which will be useful. Of significance is the Water Movement column. This describes the general flow of precipitation on each of the slope units. As expected, the upper slopes drain water to the lower slopes, which, during periods of high rainfall, would show seepage or temporary ponding. These are very important features to identify and record.

2. Boundaries or Edges

Boundaries or edges are where two or more habitat types come together. These natural or induced (man-made) features tend to have a high diversity of species because they contain overlap between habitats; therefore these areas include species found in each. As well, you may find certain species which are not generally found in either of the adjoining habitat types, as they are attracted to edges. This is particularly true of bird species.

Diagram 2

Look for the following types of edges:

a. Deciduous-coniferous forest edges

This boundary is indicated by the types of tree species providing a particular kind of habitat. In some areas this would be alder woodlands adjacent to evergreen forests. In other areas these edges would be indicated by alder, willow, trembling aspen, cottonwood etc.

b. Successional forest edges

There are six successional stages of a forest exempli­fied in the following diagram.

Diagram 3

c. Forested-non-forested edges (natural)

This category includes open rock bluffs or natural meadows with adjacent forests.

d. Forested-cleared edges (human induced)

This includes logged areas, pastures, building sites, roads and so on.

e. Land-water boundaries

This applies to open water conditions such as lakeshores, beaches and ponds (natural, small reservoirs and dugouts).

f. Stream edges

Streams and stream corridors are vitally important not only to humans but also to the survival of many species of animals. You should include not only the stream edge but also the usually deciduous tree and shrub-dominated zone known as the riparian zone. This zone is also present around the margins of lakes and ponds.

Diagram 4

g. Cliffs

These too represent a type of edge that should be recorded.

3. Wetlands

Wetlands are another vitally important component of the landscape. Include all wet areas that generally have standing water and specialized vegetation. This could include marshes, bogs, seasonally wet areas, swamps and saltmarshes.

Did You Know?

Wetlands are one of the most productive systems in any part of the world. They are essential to the survival of many species of animals, including amphibians (frogs, toads, salamanders and newts). They are able to store large volumes of water so that a sustained supply is released to streams during low rainfall periods. They regulate water temperature which is crucial to the survival of the eggs and young of fish, amphibian and insect species (important food for other species). Some wetlands represent important ground-water recharge areas. How many species use or depend on wetland-riparian systems? Study the following table produced for the forests of western Oregon and Washington; forests similar to those in western Canada.

4. Vegetation

You may need some reference material to help identify the vegetation species found in your area. See the Resources Section for some useful biophysical guidebooks. In addition, you could ask a local naturalist or biologist to help identify species found in the area you are surveying.

Be aware that vegetation grows in a general series of layers of varying heights. The layers represent the ecosystem structure and contribute to its diversity.

Using the forest as an example, four general layers would be useful to identify. They are: Overstory – the highest of the trees in the canopy. Understory – the next level of trees form a secondary canopy. Shrub layer – includes the tallest shrubs and tree saplings. Ground cover – includes the shorter shrubs, seedlings, grasses, wildflowers and mosses.

Diagram 5 will help you decide which layer to assign. Note the relative importance of the different layers to specific bird species.

Diagram 5

For each layer you can identify the following features:

a. Tree species present

This can include not only the species but also a measurement of each tree’s diameter at breast height (or dbh as foresters call it). To measure dbh:

Use a tape measure or string to measure the distance around the trunk at a height above the ground of 1.3 metres or about 4 feet. This is the circumference. Use this measurement in the following calculation.

Diameter = Circumference divided by 3.14 (pi)

b. Veterans

These are individual trees significantly older than trees of the main canopy.

c. Snags

These are the dead and dying trees in the canopy and should be recorded using the following coding as a measure of their distribution. It is important to record their condition. A decay class rating is provided below. The importance of a stock of snags, dying and downed wood is illustrated in the following diagrams.

Diagram 6
Diagram 7

Did You Know?

Snags can remain standing for many years, but eventually they will fall either as pieces over time or in one event. If stewardship and habitat values are important then snags must be a component of the forest. Knowing this, building roads or structures next to dead, dying and mature live trees (your future snags) would be avoided.

d. Canopy closure

This refers to the percentage of sky blocked by the crowns of trees when looking straight over head. The following diagram will help you estimate this.

e. Shrub species present

It is important to identify the berry producing shrubs as they represent a food source for humans and other species. Again, identification books can be helpful for both Shrub and Ground Cover.

f. Ground cover

You can also use Diagram 8 to record the percentage of ground cover. This should include downed wood and rotting logs. As well, each plant species can be assigned a Rating Code based on observations within the given area. (See next column – top)

Diagram 8

Rating Code

  1. rare • one plant within visual range (apx. 10 m.)
  2. sporadic • 5 to 25 plants within visual range
  3. patch • up to 3 patches within visual range
  4. several • 25 to 100 plants within visual range
  5. clumps • 3 to 10 patches
  6. patchy • over 10 disjointed patches
  7. uniform • many well spaced plants
  8. continuous • many plants in almost continuous coverage
  9. dense • no openings present in ground cover.

Did you know?

DECIDUOUS FORESTS provide some or all of the requirements for about 200 species of wildlife. They are the preferred trees for most woodpecker species to excavate for nests. These excavations in turn support about 22 species of secondary cavity users. Deciduous systems are an important browsing and foraging source and have a generally higher nutrient content than coniferous systems. More insect species are found here than in coniferous forests.

5. Human Land Use

Remember to record all human features such as buildings, roads, paths/trails, gardens, wells, and so on. If you know of any features of cultural, native or historical significance, then these should be recorded for the map. (See Chapter 7 for a Menu of Features, including human, that can be mapped.)

6. Wildlife

Determining what wildlife uses the habitat on the land you are mapping can sometimes require a bit of detective work. If you live on the land, take notes throughout a two year period, giving you a more thorough inventory. However, if time is a constraint, there are other ways of discovering who shares the land. Watch for the following:

  1. Browsing evidence – look for signs of deer or other mammals feeding on shrubs and other vegetation. Record the species of plants, if possible.
  2. Pellets, droppings, scat – recording these will give you some incidental information on wildlife use of your area. Look for: pellet groups from deer; “white-washing” at the base of trees used by roosting hawks, owls and eagles or if it is found on shore rocks or cliffs, indicating gulls or seabirds; and scat piles with fish bones, shells and so on indicating mink or otter use.
  3. Bird species detected – include here observed bird species and what they were doing (feeding, roosting, nesting, perching, etc.). Old snags with evidence of woodpecker cavities and foraging activities would be a useful addition to your snag inventory.
  4. Other wildlife species detected – include observations of amphibians, reptiles, small mammals (mice, squirrels) and larger animals actually observed. Remember to include a note of what they were doing at the time of observation.
7. Soils

You should consider a general description of the soils of your home place. It is believed that in temperate forests the true biological diversity is indicated by the organisms inhabiting the soil. This includes insects, worms, nematodes, mites, bacteria, fungi and other microscopic organisms. Many of these organisms are critical to the health of species (primarily plants) which grow here. For instance, a group of bacteria is able to convert atmospheric nitrogen into a more readily usable form for plant uptake through their roots. These are referred to as “nitrogen-fixing bacteria” and are associated with such tree species as alder. (Look for the small nodules on the alder roots.)

In light of this, consider digging some soil pits at several locations around your home place. At each pit measure and record the various soil layers or horizons. Diagram 9 will help you identify each of these layers. Your pit should be at least deep enough to expose two changes in horizons or soil textures.

Snag Table

In addition to data from your soil pit, the type of soil can be roughly determined using a number of field techniques. The following are some useful field tests for you to try.

a. Graininess test

Rub soil between the thumb and forefinger to assess the sand content by how grainy the sample feels.

b. Dry feel test

Start with moist sample and rub in the palm of the hand until dry. Separate out and estimate the sand particle content. The sand particles will then fall out of your hand and the remaining finer material (silt and clay) can be estimated. Silt has a floury feel while clay feels smooth.

c. Stickiness test

Knead a wet soil sample until it reaches its stickiest point. Roll into a ball and squeeze between your thumb and forefinger. The degree of stickiness is determined by how strongly it sticks them together and how much it stretches as you release pressure. Clay is very sticky while silt feels slightly sticky to soapy.

d. Taste test

Not for the weak stomach. Work a small amount of soil between your front teeth. Sand can be distinguished as individual grains against the teeth. Silt particles have a generally fine grittiness, but individual grains cannot be distinguished. Clay is smooth, having no detectable grittiness.

All of these tests will help you to determine the sand-silt-clay content of your soil. Each of these textures can be found in varying combinations in your soil sample such as silty sands or clayey silts. You can judge the relative proportions of each.

Diagram 9
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