Grazing Forested Rangeland

Introduction

Saskatchewan’s forested rangeland supports a diverse number of uses, including grazing, forestry, tourism and recreation. How this rangeland is managed and used for domestic livestock has a direct impact on other land uses and values. Livestock grazing can change a forested area’s plant composition and the quality of plant life. It can also have an affect on soil properties, water shed functioning and many wildlife species that depend on these areas. Healthy forested rangeland is essential to soil and water conservation, nutrient cycling, air quality and other ecosystem functions that directly or indirectly benefit everyone.

Grazing response and assessing range condition

Aspen is the dominant tree cover in much of the grazed, forested rangeland. Aspen occurs over a wide range of moisture and nutrient conditions. As a result, a variety of understory communities can be identified based on the dominant shrubs and herbs present.

In these communities, livestock will exhibit preferences for certain species, due mainly to palatability and availability factors. However, there are a number of species with similar responses to grazing in all community types. The designation as a decreaser, increaser or invader is based on a comparison of grazed to ungrazed stands of similar type. Response to grazing of some of the more common understory plants in these communities is given in Table 1.

There are a number of methods for estimating range condition in forested communities. All methods consider one or more of the following site conditions:

1. Understory composition.
2. Understory structure (height and density of grass, forb and shrub layers).
3. Overall productivity of palatable species.
4. Aspen regeneration.
5. Litter levels on the forest floor.

The most preferred method of range condition assessment in forested rangeland focuses on the understory vegetation, comparing grazed areas to ungrazed areas or areas receiving little use. The vegetation component is the focus of range condition assessment simply because it provides direct feedback on the impact of grazing. Vegetation assessments are more indicative and sensitive to the health of the resource than using other indicators, such as animal production or stocking rates.

Overgrazing has the potential to reduce or eliminate the palatable understory species from the shrub, grass and forb layers. Continued overgrazing can result in the establishment of invader species, exposure of soil, soil compaction, reduced water infiltration and lack of aspen regeneration. In addition, riparian areas that are preferred grazing areas can become severely degraded due to trampling and over use. These degraded riparian areas are often prone to establishment of invader species, such as Canada thistle and foxtail barley.

Table of Contents

Range use

To determine proper levels of use on forested rangeland, it is important to consider use of key species in key areas. Key species and key areas serve as indicators of management effectiveness.

In most cases, one to three plants are used as key species. These plants should be abundant, productive and palatable. Key species are usually decreaser species that are valuable for livestock grazing. Decreaser species will be in short supply if the range has been overgrazed, but they have the potential to become abundant if grazing pressure is reduced. Species such as aspen, ricegrass, creamcolored vetchling, peavine and saskatoon can be used as key species. Forested rangeland should be managed to maintain these species. When the frequency of these species begin to decline, it indicates overgrazing.

Key areas are the portions of range that serve as an indicator of range condition, trend or degree of use. The key area concept is based on the idea that no range of appreciable size will be used uniformly. Key areas will be located in areas where livestock prefer to graze, but should not be located in close proximity to water sites, salting areas or where livestock congregate for reasons other than grazing. An indicator of grazing sustainability is the abundance of key species in key areas.

The level of use of the current year’s growth that palatable vegetation can withstand without lasting detrimental effects is sometimes referred to as the proper use level (PUL). The PUL varies depending on the type of vegetation and the season of use as indicated in Table 2. PUL must also consider use and potential use by wildlife throughout the year.

Determining primary, secondary and non-use range

Grazing land can be separated into primary, secondary and non-use ranges. Primary range is considered to be the areas that animals prefer to use when management is low. The areas that are lightly used or unused by livestock under minimal management are considered secondary range and will ordinarily not be fully used until the primary range has been over used. Areas that livestock will not use for grazing are considered non-use range. In forested rangeland, primary range tends to be those areas close to entry points, water sources and open meadows that are easily accessible. Secondary range tends to be those areas that have limited use because of distance to water, slope or poor access, due to terrain or vegetation. Non-use ranges are those areas that are not suited to livestock grazing, such as solid spruce or jack pine bluffs. However, these areas may still be used by livestock for cover and shelter.

Grazing management in forested rangeland strives to increase the amount of primary range by reducing the amount of secondary range. Fencing, water development, salting, herding and access trail construction are all effective tools. It is important to remember that even with improved management, not all secondary range will be used effectively; therefore, only the expected increase in use should be considered when determining stocking rates.

Many of the large tracts of forested rangeland are important for a variety of uses (particularly wildlife), rather than solely for livestock production. In some cases, there is potential for competition of livestock with wildlife species for food, water or space. In situations such as this, it has been suggested that the concept of managing for optimum livestock distribution and use may not be desirable. The maintenance of primary grazing areas with a gradient to areas of non-use by livestock may be a more suitable management approach. Where multiple-use management for wildlife and livestock is important, greater emphasis needs to be placed on stocking rates, time of grazing, range classification, setting practical objectives and planning.

Table of Contents

Setting initial stocking rates

The most important management consideration for any grazing program is matching forage use to availability. The productivity of forested rangeland is largely related to tree cover. The resulting shading effect of a dense tree cover limits the growth of grasses and other forage plants, reducing the suitability of the site for livestock grazing. Less dense tree cover allows for greater light penetration, and the development of a more pronounced shrub and forb layer. Productivity of the understory is also related to the nutrient status of the soil on which different tree species occur.

Forested rangeland has a wide range of forage yields. Yields from various sites in The Saskatchewan Benchmark Project (1990-1994) show variations in yields in excess of 1,100 pounds per acre. The ranges in initial stocking rates in Table 3 reflect this variability. The classification of community types is a basic starting point to assess the grazing potential of forested rangeland. The use of a rigid stocking rate for aspen and other forest types is not recommended, as not enough information is yet known on yields or grazing response of understory plants. For this reason, an initial stocking rate should be selected and a monitoring plan should be implemented to fine tune the stocking rate over the course of the grazing season and subsequent years.

Balancing the number of animals and/or the level of use with the forage supply are important in range planning. However, there are many factors that should be considered when setting an initial stocking rate, including:

1. What is the condition and approximate yield of palatable forage plants?
2. When is the best period to graze the forest?
3. How long should the forest be grazed?
4. What level of forage use is acceptable considering the present condition of the understory vegetation?
5. How do livestock distribute themselves in the forest and what proportion is primary, secondary and non-use range?

Table of Contents

Season of use

Next to proper stocking rate, season of use is probably the most important management consideration. For forested rangeland, season of use is important for maximizing both forage value and production.

Forage value is related to both the nutritional value of a forage species and its preference by the animal species concerned (i.e. cattle, deer, etc.). Cattle tend to be grazers. Although cattle prefer grasses and forbs, browse species can make up a considerable portion of their diets on forested rangeland.

Many plant species in forested rangeland make good quality forage for livestock. Forage value is highest in the spring and declines as the grazing season progresses (Graph 1 and 2).

Forested rangeland is generally considered ready for grazing in mid- June. As forbs and shrubs often dominate understory communities, grazing taking place earlier than mid- June can have negative impacts on forage production. If grazed too early, growing points are removed and plants may not grow again for the rest of the season. Also, grazing too early does not allow plants to replenish energy used to over winter. Thus, delaying grazing until significant growth has occurred will increase the yearly productivity of the range.

Grazing on forested rangeland should be completed by early fall. On forested rangeland, forage plants lose most of their nutrient value following the first killing frost that often occurs at this time.

If forested rangeland is required for a longer season, it is better to extend the grazing season in the fall rather than put livestock on earlier in the spring. This will result in less impact on the vegetation, as plants are more tolerant of defoliation during periods of dormancy. Low forage quality in the fall can be overcome by supplemental feeding. Mineral supplementation is recommended during all grazing periods.

Grazing systems for aspen range

Intensive grazing systems for forested rangeland are impractical for two reasons. Firstly, stocking rates are low, often making investments in capital improvements such as fencing and water sites uneconomical. Secondly, the cost of capital improvements may be much higher on forested rangeland than grassland. This is because access for equipment, as well as site preparation for both water sites and fence lines, often involves clearing and breaking. In addition to these costs, long-term maintenance costs will be higher due to tree-fall and wildlife damage, as well as aspen regrowth control on fence lines and trails. However, on large tracts of productive range where distribution is a problem, some expenditure on additional water sites, fencing and laneway development may be appropriate. Proper location of developed pastures, fencing, salting and watering areas may increase use of less preferred areas. Trail development can provide livestock with access through areas of thick brush or rough topography. Trail development connecting open meadows can greatly improve the grazing efficiency in forested rangeland.

The best grazing system for forested rangeland is a complimentary system with seeded pastures. This system uses tame forages for early- and late-season use and relies on the forested rangeland for grazing from mid-June to early fall.

Table of Contents

Monitoring

Monitoring is extremely important in forested rangeland. Monitoring should be carried out on a frequent basis in order to assess the current level of forage use so stocking rates can be adjusted. Utilization measurements on key areas can be used to estimate proper stocking levels under current management practices. Monitoring provides the basis on which to make decisions on range readiness, when to move livestock and degree of use. It also allows producers to identify problem areas early before they become serious.

Longer term monitoring normally focuses more on the changes in the understory structure and composition. These changes can often be quite slow and subtle, and therefore monitoring of this nature is carried out generally every three years. Monitoring and evaluation are the keys to determine when management changes are needed. It is critical that both monitoring sites and methods be sensitive to changes in the resource. The sites chosen for monitoring must therefore be sensitive to current management, changes in weather patterns and changes in livestock distribution, and should also reflect short and long-term objectives. Some guidelines to use when monitoring forested rangeland are presented in Table 4.

Table 4. Criteria for Monitoring Grazing in Mixed-wood Forests

More detailed information on monitoring is listed under references and suggested readings.

Conclusion

The basic principles for management of forested rangeland are the same as those for native grassland. Planning and the setting of practical goals and objectives will provide the starting point of management practices. Stocking rates, monitoring season of use and distribution practices are all components of a range management plan that can help producers meet their goals and objectives for forested range.

References and suggested readings

• Abouguendia, Z. 1998. Nutrient content and digestibility of Saskatchewan range plants. ADF Technical Report 94000114.
• Adams, W. and A. Robertson. 1990. Two worksheets for range vegetation monitoring. Range Notes, issue No. 8. Alberta Public Lands.
• Anonymous. 1995. Managing Saskatchewan Rangeland, Revised Edition. Grazing and Pasture Technology Program, Ducks Unlimited, PFRA, Saskatchewan Agriculture and Food.
• Beckingham, J. D. 1990. Lathyrus ochroleucus - microclimate and grazing. A Thesis, Dept. of Geography, Univ. of Alberta, Edmonton, Alberta.
• Ehlert, G. and D. Downing. 1994. Managing aspen rangelands in Alberta’s boreal mixedwood ecoregion: The Northeast Region Benchmark Program. Range notes, issue No. 17. Alberta Public Lands.
• Ehlert, G. 1990. Draft aspen mixed-wood range condition score card (use with LG32/MF5).  Range Management Section, Public Lands Division, Northeast Region. Alberta Agriculture publication.
• Foster, A. 1994. Field Guide, Identification of Common Range Plants of Northern Saskatchewan, Grazing and Pasture Technology Program.
• Godwin, B. and J. Thorpe. 2000. Ecological health monitoring for the native grasslands of Saskatchewan. SRC publication no. 11109-2E00.
• Jorgenson, T, A. Foster and Z. Abougendia. 2000. Seasonal growth pattern and effect of annual clipping on white grained mountain ricegrass (Oryzopsis asperifolia) productivity. Final report, Grazing and Pasture Technology Program.
• Kabsems, A., A. L. Jisiwab and W. C. Harris. 1976. Mixed-wood section in an ecological perspective. Saskatchewan Tourism and Renewable Resources. Prince Albert, Saskatchewan. Tech, B. 8. 118pp.
• Rowe, J. S. and G. W. Scotter. 1975. Fire in the boreal forest. Quarterly res. (N.Y.) 53:444-464.
• Society for Range Managment. 1993. Guidelines and terminology for range inventories and monitoring. Report of the range inventory standardization committee, Society for Range Management, Denver, Colorado.
• Valentine, J. S. 1990. Grazing Management. Academic Press, San Diego, California.

Acknowlegements

The authors wish to thank Gerry Ehlert, Manager of Grazing Reserve N. East Region, Alberta Public Lands; Chris Nykoluk and Bill Houston, Range Management Biologists, PFRA for their comments and suggestions.

Prepared by:

Todd Jorgenson and Allan Foster, Forage Development Specialists, Saskatchewan Agriculture and Food.