Factsheet 3 of 6 in the
Pasture and Range Assessment Series

Introduction to Pasture and Range Health

ASSESSING NATIVE RANGE

Use the assessment in the table below for pastures (rangelands) dominated by native plants. If the pasture is dominated by tame species (crested wheatgrass, brome grasses, orchardgrass, etc.), please refer to the Factsheet 4, Tame Pasture Assessment.

Detailed Explanation of Native Range Assessment Questions

Native Range Question 1

Do desirable plants make up more than one-half of the vegetation cover or weight?

Significant disturbances like continuous heavy grazing, prolonged periods of drought or high precipitation, invasive species invasion, frequent burning, intensive recreational activity, and timber removal can all impact plant community composition. Heavy grazing weakens desirable forage plants, thus shifting the competitive advantage to low growing, disturbance induced, undesirable plants including low growing native plants such as pussytoes, strawberry, yarrow or other exotic invasives including dandelion, knapweed, Canada thistle, leafy spurge, etc. Undesirable plants can include those that are invasive and crowd out desirable species or are poisonous. Examples of desirable plants are provided in Table 1.

• Desirable plants are those plants that contribute positively to the management objectives of the site while maintaining the nutrient and water cycles as well as maximizing energy flow. In most cases, on private grazing lands, desirable plants should be those plants that:
  • are perennial
  • are readily consumed and persistent
  • provide consistent and high amounts of forage
  • prohibit the introduction or spread of invasive plants
  • provide enough litter and residue to conserve soil moisture and maintain soil stability

•  In grassland situations, desirable plants typically include:
  • low shrubs (e.g., low valley grasslands)
  • tall grasses and forbs
  • medium grasses and forbs
  • ground cover (grasses, forbs, moss, and lichen)

• In forested situations, desirable plants typically include
  • low, medium and tall shrubs
  • tall forbs and grasses
  • medium forbs and grasses
  • ground cover (moss and forbs)

Scoring Hints

If this question is difficult to answer, find a reference site that occurs in a similar plant community. This reference site can be an area that is lightly to moderately grazed. In forested plant communities, these reference areas occur well within the forest, generally over 100 meters from fences, water sources, trails, cut-lines, etc., or on the other side of fences or natural barriers. In grasslands, reference sites are often located over 500 meters from water and away from fence lines. They can also occur on the other side of a fence or natural barrier or in areas that are separated from highly utilized areas by rugged topography. It is important that the reference plant community has adequate resistance to and resilience from most disturbances.

The following websites provide useful information on the identification of the plants mentioned in this table.

1. Photographic guide to common range plants of British Columbia
   Website address: http://www.cwnp.org/photoindex.html
    
2. National Resource Service Plant Database.
   Website address: http://plants.usda.gov/

Examples of Desired Plant Communities

Southern Interior grassland composed of more than one-half productive and desirable bunchgrasses grasses.	A lodgepole pine forest composed of more than one-half highly-productive and desirable grasses (predominately pinegrass).
A Northern Interior cutblock composed of a mixture of desirable shrubs, forbs and grasses.	Peace River aspen stand with an abundance of desirable plants including highly productive grasses, forbs and shrubs.

Native Range Question 2

Are desirable plant species abundant in all age and size classes?

To maintain or improve the health of pastures it is extremely important to ensure that desirable plants are abundant in all age and size classes. This not only ensures the continued recruitment of desirable plants, it also favours a more diverse plant community with varied canopy structures and rooting depths. These communities assist in maintaining the nutrient and water cycles and maximizing energy flow by using sunlight, water, and nutrients from different zones in the canopy and soil. Desirable plants in all age and size classes also provide habitat for numerous wildlife species including browsing opportunities for ungulates and feeding and nesting sites for birds and small mammals. If young plants are not establishing and existing plants are either dying or dead, the health of the pasture in question is in decline. Healthy pastures have a mixture of many age and size classes.

Heavy grazing tends to limit the abundance of desirable plants in both age and size classes. For example, overuse of shrubs in grassland and forest situations will reduce wildlife habitat of some species. Heavy grazing can also reduce the structural diversity (removal of different grass size classes) in grassland plant communities. In most native grassland communities, patchy grazing is preferred when managing for habitat diversity. It is also important to note that some wildlife species prefer large areas of uniform use.

Scoring Hints

• In grassland situations, expect to see the following desirable plants in a variety of age and size classes:
  • low shrubs (e.g., low valley grasslands)
  • grasses and forbs
  • ground cover (moss and lichen)

• In forested situations expect to see the following desirable plants in a variety of age and size classes:
  • low, medium, and tall shrubs
  • forbs and grasses
  • ground cover (moss and forbs)

• Note that a loss in desirable species, age and size classes may be due to climatic conditions and historical management and thus may have nothing to do with current management.

• The presence of mosses and lichens maximizes energy flow, nutrient, and water cycling while the loss of these species may be attributed to over-use (trampling) or non-use (shading by litter).

If unsure as to whether some age/size classes of desirable plants are missing, look for grazing/browsing impacts on plants. For example, browsing of unpalatable shrubs like soopolallie, snowberry, or sagebrush usually indicates that more desirable plants have been reduced or eliminated by overuse.

Native Range Question 3

Does leaf length, seed production, colour, and overall productivity of desirable plants indicate strong vigour?

Plant vigour is reflected by the size of a plant and its parts in relation to its age and the environment in which it is growing. It is important to note however, that periodic drought is common in dry land environments and will lower the apparent vigour and annual productivity of desired plants.

Plants with low vigour have a greater potential to be replaced by weedy invasives and other low quality or poisonous plants.

Scoring Hints

• when determining vigour, concentrate on the vigour of individual desirable plants.

Peace River aspen stand showing excellent vigour and a loss of desirable tall forbs and shrubs.	Peace River aspen stand showing poor vigour, productivity and mixture of desirable tall forbs, grasses and shrubs.
Southern Interior bunchgrass grassland showing poor vigour, productivity and a lack of desirable large bunchgrasses.	Southern Interior bunchgrass grassland showing excellent vigour, productivity and a dominance of large, more robust bunchgrasses.

Native Range Question 4

Is there any evidence of overuse (hedging) on shrubs and/or trees?

Scoring Hints

Answer Yes, if you fall under the category of heavy use after completing the following test.

Evidence of shrub or tree overuse:

• first, randomly pick 2 to 3 plants of each of the preferred woody species (e.g. willow, saskatoon, rose, dogwood)
• for each plant, select a branch that would be available or accessible to browsing animals and count the total number of leaders (twigs) on the branch
• now count only the older leaders (2nd year growth and older) that have been clipped off by browsing
• determine the percentage of utilization by comparing the number of leaders browsed with the total number of leaders available on the branch; and do not count current year’s use since an estimate in mid-season does not accurately reflect actual use, because browsing can continue year-round

The diagram and photo below will assist you in answering this question.

Photo of a heavily used willow.

Light Use - Shrubs of this nature generally have open, loose crowns and produce a large quantity of vigorous twigs. Their appearance is that of healthy, fast-growing plants. Unused (non-browsed) plants are included here.

Moderate Use - These shrubs possess moderately open crowns but show signs of some hedging. Plants that are used to this degree exhibit varying levels of vigour and begin to take on a ragged appearance. Some of the twigs are readily available while the remaining twig growth is generally unavailable due to the tight growth forms and presence of larger clubbed stems on the periphery of the crown.

Heavy Use - A closed, compact rounded appearance is usually characteristic of heavy use on a mature plant. Generally, very little twig growth is present on the exterior portion of the shrub and most of the twig growth is confined to the interior. A decadent plant often shows signs of close hedging on the few larger stems that produce limited leader growth. Young plants are generally not very common in a closely hedged shrub community.

In addition to determining tree and shrub use, the following indicators may be used to determine whether tree/shrub populations are expanding, stable, or diminishing:

• expanding populations – age distribution within these populations is generally pyramid shaped with many young (small size) individual plants forming a wide base, fewer middle-aged plants (medium sized), and very few old (large) plants at the top

• stable populations – age distribution within these populations is generally “bullet” shaped, with approximately equal amounts of young and middle-aged (or size) plants forming the middle and base, and fewer older (larger) plants at the top

• diminishing populations – age distribution within these populations is generally “urn” shaped, with a narrow base (sometimes absent) of young (small) plants widening toward the older aged (medium sized) plants, then sharply narrowing with the oldest (largest) plants at the top

Native Range Question 5

Is litter and plant residue fairly abundant and some of it composed of desirable plants?

Litter and standing plant residue (dead material), in various states of decay, provides additional surface cover and promotes nutrient cycling by providing organic matter and nutrients to the soil. The additional cover provided by this material reduces soil erosion by wind and water including reducing raindrop impact. Litter and plant residue also promote moisture retention by reducing evaporation and increasing water infiltration into the soil by slowing runoff and providing a pathway into the soil profile.

In general, litter and plant residue is directly related to weather and the degree of forage use each year.

Scoring Hints

• To be able to answer Yes to this question, 25 to 50 percent of the standing forage mass should either be dead or consist of dying leaves and stems.

• Also, note that too much litter and standing plant residue (dead material) will reduce the quality of forage consumed, as well as inhibit new plant shoot growth and seedling emergence. Anything greater than 50 percent may be excessive.

Southern Interior grassland with relatively little litter.

Southern Interior bunchgrass grassland with fairly abundant litter and plant residue (>25%), some of which is composed of desirable plants.

Native Range Question 6

Is there evidence of soil compaction, soil movement, or its loss?

When managing native rangelands it is extremely important to prevent human caused soil movement or loss by maintaining adequate plant cover and minimizing the amount of exposed (bare) soil. Any loss of soil will lower the productivity of a site by removing finer soil particles like clays, silts, and organic matter all of which are integral in maintaining soil fertility and the site’s moisture holding capacity. The potential for soil movement (i.e., rill and gully formation) increases with increasing slope and the loss of plants, plant residue and litter. 

It is also important to minimize soil compaction. Soil compaction decreases the amount of water available to plants by reducing water infiltration into the soil profile. Most compaction occurs when rangelands with saturated soils are grazed or subjected to heavy equipment. Compacted layers often occur less than 15 centimetres from the soil surface. It is also important to note however, that most upland compacted soils in British Columbia tend to recover (i.e., break up of compaction layers) quickly due to frost heaving and earthworm activity.

Drawings and corresponding photographs on the following pages will provide examples of soil compaction, soil movement, and its loss.

Scoring Hints

• Answer Yes, if any of the following are observed:
  • the presence of debris dams of plant residue that build up at obstructions or span between obstructions (sheet erosion);
  • the presence of rills, which are small incised channels that run parallel to one another down a slope. The presence of rills indicate that serious soil loss is occurring;
  • soil is deposited downwind of obstructions such as fence lines, buildings and individual plants;
  • the movement of litter on the site (i.e., litter concentrated around rocks or woody debris).

• Also, note that too much litter and standing plant residue (dead material) will reduce the quality of forage consumed, as well as inhibit new plant shoot growth and seedling emergence. Anything greater than 50 percent may be excessive.

• Answer Yes, if there is a noticeable difference when completing the following test:

Evidence of soil compaction:

• push a metal rod, pencil, or knife into the soil and interpret the ease of penetration
• compare in-field resistance to penetration with resistance found at a grazed fence line
• compacted soil layers will increase the amount of resistance encountered
• the more noticeable the difference in resistance, the greater the compaction is at that site

Examples and drawings of soil compaction, soil movement, or its loss

Example of rills on a Southern Interior grassland.
Example of a gully on a Peace River pasture.
Example of compaction in an aspen poplar forest.	Notice the elevated roots.
Other signs of soil disturbance/ loss include:
Trailing.	Hoof Shearing.

Please note: Minor amounts of trailing are common on many pastures and ranges. Winter ranges can be especially prone to hoof shearing.

Native Range Question 7

Are plant roots exposed or are there other signs of pedestalling?

Pedestalled plants and rocks are another sign that soil loss has occurred. Any loss of soil will lower the productivity of a site by removing finer soil particles such as clays, silts and organic matter all of which are integral in maintaining soil fertility and a sites moisture holding capacity.

Scoring Hints

• Answer Yes, if any of the following are observed:
  • plants on pedestals with exposed roots
  • gravel and rocks are exposed or sitting on the soil surface
  • lichen lines are visible on rocks

Notice how the plants appear to be on pedestals

Following the completion of this assessment proceed to factsheet 5 of this series to help you identify any concerns from the assessment and select revised management practices.

For further information contact:

Darren Bruhjell
Phone:  250 371-6058
Email: Darren.Bruhjell@gov.bc.ca

Back to Range Factsheets
Back to Industry Competitiveness Branch Home