Range management and its ecological basis in the ponderosa pine type of Arizona : the status of our knowledge /

The purposes of this Paper are to summarize and evaluate the available physical, biological, manage ment, and economic data for the Arizona pine- bunchgrass ranges.It provides information intended to help public and private managers of forest-range lands in making resource management decisions, and to help researchers make decisions concerning pos- sible new research directions.The information provided follows this sequence: physical-biological characteristics of the Arizona ponderosa pine type, factors influencing livestock (primarily beef) production, allotment conditions, economics, and correlation of grazing with other uses and demands.The following conclusions can be drawn from this information: 1. Considerable descriptive information is available for the Arizona ponderosa pine type.Knowledge of geographic, climatic, edaphic, and vegetation characteristics is adequate for use in reaching many management decisions.2. The successional stages of the bunchgrass ranges appear to be sufficiently understood so that general range condition can be easily recognized.3. A good background of range seeding information is available, and the causes of livestock losses from poisonous plants are understood.4. A good information base on forage nutrition applicable to summer grazing has been developed for ranges dominated by Arizona fescue and mountain muhly.This base can be used as a guide to management needs when compared with the nutritional requirements of the livestock in question.Similar nutritional information should be developed for other ecological situations and for other seasons of the year. 5. Information available on the factors influencing herbage yields on volcanic soils should provide usable predictors of herbage production and how it is affected by timber overstory densities and manipulations.Similar information should be developed for sedimentary soils.6. Potential beef gains can be predicted from nutrient consumption, and potential livestock carrying capacity can be predicted from timber density and forage composition.However, computer models capable of simulating animal distri- bution are needed to predict changes in actual livestock carrying capacity and production so that land managers will have better advance information concerning the effects of vegetation manipulation and various grazing management procedures.7. The tree basal area that will provide maximum combined product value for joint beef and saw- log production has been determined for pon- derosa pine-bunchgrass ranges to be between 45 and 60 square feet per acre.8.No information was found that suggests that proper range use conflicts significantly with other forest uses, although more information is needed concerning the relationships of livestock grazing to nonruminant wildlife and general recreational values.9. New inventory techniques are needed to provide up-to-date data on forage production and use, range condition and trend, animal numbers, and vegetation types.10.National Forest System procedures for land use planning in some regions are now based upon assessments of land capability and sensitivity (USDA-FS 1972b).To adequately apply these procedures, information is needed on the impact of livestock use on erosion processes for the various forest and range sites.11.Information is required concerning the effectiveness of different grazing systems as they specifically apply to the Arizona ponderosa pine type.It is suggested that allotment data for the South- western Region, R-3 of the USDA Forest Service, be intensively analyzed to document the effect of different grazing systems applied under different conditions.12.A major effort in habitat typing has been pro- posed for the Southwest.This information is considered to be an essential base for future management planning, including grazing man- agement.Three of the major differences that can be expected among habitat types are in forage production potential, initial composition of for- age plants, and the manner in which the compo- sition responds to different grazing management procedures. 1 13.Much of the work to be done on Arizona pon- derosa pine ranges is in the area of range condition improvement.Past managerial short- sightedness often resulted in depleted ranges and impaired environmental quality.Sufficient infor- mation is available-and has been for years-to define a suitable path toward maintenance and improvement of the western ranges (USDA-FS 1936, Stoddart and Smith 1943, Sampson 1952).Where applied, existing information in the areas of forage use, livestock distribution, rest or defer- ment, reseeding, and control of invading plants will go a long way toward gradually getting ranges back in top shape.The difficulty, of course, is that most of these measures require added investment or intensified management, which necessitates examination of short-and long-run economic and financial tradeoffs.As these decisions can directly affect ranching profits, more information is needed on the economics and finance of range improvements.This kind of information will give managers a stronger basis for making tradeoff assessments and substantiating their decisions.14.The day of functionalism (management for indi- vidual products or values) in managing most forest-range lands is close to being over.Range managers, particularly those dealing with public lands, need to maintain a multiple-use management perspective.All potential uses of the forested range have to be jointly considered when changes in management of a range are contem- plated.Grazing practices which appreciably damage or hinder other significant products or amenities of the forest will normally have to be curtailed.On the other hand, by recognizing improvements in several products of the forest, some very worthwhile management practices may become economically defendable that otherwise would not have been if only one product had been considered.An example of this is the benefit to range, water, and timber production which accrues from suitably thinning timber stands.Physical Characteristics Geographic Ponderosa pine 2 dominates 3,657,600 acres or 92 percent of the State's commercial forest land (Spencer 1966).The ponderosa pine forest is for the most part equivalent to Merriam's Transition Life-Zone.The lower elevation is between 5,500 and 7,000 feet, and the upper elevation between 8,500 and 9,000 feet, varying according to slope and exposure.Pure stands occur most commonly between 7,000 and 8,000 feet.2 Common and botanical names of plants mentioned are given at the end of this Paper.