By Allan Foster, PAg., Range Management Extension Specialist, Tisdale
When we think of rangeland, trees are not usually the first thing that comes to mind. However, for many livestock producers in the parkland of Saskatchewan, aspen pastures are a valued rangeland resource. Like the grasslands to the south, these native ranges require proper management in order to remain productive. For those larger blocks of aspen pasture, a grazing program based on proper stocking rates, season of use and livestock distribution will maintain both livestock production and healthy vegetation.
The most important management consideration for any grazing program is matching forage use to availability. The productivity of aspen pasture is related to the type of plants growing under the aspen canopy. In aspen-dominated pastures stocking rates will vary depending on soil conditions, tree density, understory type and past use. In many cases stocking rates are similar to native grasslands in southern Saskatchewan.
Just as in native grasslands, stocking rates in aspen pastures should ensure that not more than 50 per cent of the current year’s growth of desirable species be utilized during the growing season. The loss of desirable plants such as peavine, vetch, rice grass and awned wheatgrass are indications of overgrazing. Since native legume species are highly nutritious and are most susceptible to grazing, aspen pastures should be managed to maintain these species.
The season in which aspen rangelands are grazed is an important consideration when attempting to optimize forage production. In general, plant growth on aspen pasture starts more slowly in the spring and finishes earlier in the fall than that on grassland pasture. This provides for a limited period during the summer in which these pastures are most productive and is usually from about mid-June to mid-August. Grazing earlier than mid-June can reduce the production of forage plants especially some of the more valuable forbs such as peavine and vetch. Grazing beyond the end of August will limit livestock to lower quality forage and may result in an increased use of browse species.
Because of this short season for optimal grazing, aspen pastures are best suited to a complementary grazing system which incorporates tame forages for both spring and fall grazing. Aspen range may be properly stocked and used during the proper season but still suffer from overgrazing in certain areas. Preferred areas are usually close to water, salt and mineral or near entry points. They have more lush growth or contain a higher proportion of grasses such as along sloughs or streams. Where distribution problems are evident, methods such as construction of additional water sites or access trails can be very successful. The method or methods chosen will depend on the cause of the problem as well as the net economic benefit the method is likely to produce.
The management principles for maintaining aspen pastures in a productive condition are no different than those for native grasslands to the south. Proper stocking rates will ensure livestock requirements are balanced with forage production. Proper season of use will ensure that production of both vegetation and livestock will be optimized and good livestock distribution should help to ensure productive plants are not overgrazed.
For more information on this or other forage related topics, contact Allan Foster at 306-878-8890 or the Agriculture Knowledge Centre at 1-866-457-2377.