Chemicals are often used for control of invasive weeds and brush that hamper revegetation efforts on rangelands. Agricultural herbicides undergo extensive toxicological, environmental, plant efficacy, and cost-benefit tests before being released for widespread use. This database of knowledge enables the applicator to select herbicides to fit the targeted weeds and brush for maximum efficacy, efficiency, safety, and economics. The major change in application practice has been a shift from broad-scale aerial applications to individual plant treatments with ground equipment. In either case, the application equipment has been designed for more precision and safer use. Global positioning systems (GPS) and geographic information systems (GIS) on aircraft or ground units allow the operator to "sculpt" the landscape for multiple land-uses, e.g. wildlife habitat, grazing, water harvesting, and aesthetics. Herbicides will continue to play a significant role both singly and in combination with fire and mechanical treatments in revegetation projects. Persons applying restricted-use pesticides must have state certified Applicator's License and follow specifications on the chemical's Product Label. It is important to note that the Directions for Use section of all pesticide product labels begin with the statement: "It is a violation of Federal law to use this product in a manner inconsistent with its labeling."
The use of prescribed fires to control weeds and woody vegetation, improve forage health, manipulate wildlife habitat, and reduce fire-prone vegetation is well established. Revegetation projects can benefit from the use of fire alone or in combination with mechanical or chemical treatments. Prescribed burning implies the use of stated goals and a well-thought-out fire plan using recommended equipment and burning techniques. Consideration must be given to weather, vegetation, topography, and other variables. Fire can be a very cost-effective treatment and can cover large areas of varied terrain in a short time span if sufficient fine fuel is present. Burning treatments will be spotty if the fuel load is limited. Forage production and palatability is usually increased following a burn. Seeding may also be conducted following a burn. Erosion can be a problem following a fire. Escapes from planned burns present a real hazard; therefore, trained personnel and wise judgment are vital to successful prescribed fires.
Equipment covered in this section is designed to mechanically remove invasive weeds, shrubs, and trees that would impede the revegetation of sites to plants that are ecologically adapted. Combinations of different mechanical treatments are often necessary to achieve desired results. Effectiveness of mechanical control depends on:
- selection of proper equipment and its method of application
- targeted plant and its sprouting characteristics
- site potential
- soil type
- topography and terrain
Mechanical treatments are visually apparent and usually effective, but they can be more costly than other methods. They may be the only solution when herbicide or fire cannot be used.