Holistic Resource Management of Fire, Livestock, and Oaks
Holistic Resource Management is based upon restoration and emulation of natural ecosystem relationships. It is a complex theory and practice requiring extraordinary attention and dedication from land managers. Careful regulation of livestock is one of its defining qualities.
Fire Hazard Reduction
Accumulated biomass from brushy plants and wood detritus, particularly that which lies within woodlands, under mature trees, or adjacent to vulnerable structures, is the fuel which contributes most to fire hazard on the Academic Reserve. Grazing does little to reduce this fuel, and improper grazing may increase it. Bay Area oak habitat managers prefer to remove it by burning, which also may yield substantial ecosystem restoration benefits. Intensive livestock grazing can lessen fire hazards by augmenting firebreaks or creating low-fuel areas around sensitive sites. This use of livestock might meet HRM objectives better than disking, and at substantial savings in disking expense. Mowing can lessen fire hazard from annual plant biomass in a manner less destructive than disking and less difficult to manage than grazing.
HRM Grazing Regimes
HRM guidelines for grazing rely upon high stock densities rotated through paddocks (fenced areas) to ensure thorough cropping of edible forage, followed by livestock exclusion for periods long enough to permit plants to recover the energy lost to grazing. Increasing the number of paddocks results in each paddock's being more evenly and fully grazed; it improves the ratio of recovery period to grazing period; and it enhances the likelihood that repetitive grazing with adequate intervening recovery will be possible. In all these ways, augmenting the number of paddocks lessens the risk of overgrazing, and increases utilization of range productivity. Temporary fences and full-time herd supervision are commonly necessary. Grazing by diverse livestock (e.g. - goats used in conjunction with cttle for brush control), though challenging to manage, can generate more beneficial impacts than single-species grazing. Horse owners are potential contributors to an HRM program on the Academic Reserve.
More than two thousand young oaks widely scattered across the Academic Reserve are vulnerable to grazing cattle and other predators. In the absence of measures to protect these, much of the university's investment in oak regeneration may be lost. Area exclusion of livestock and protection of individual trees are methods already proven on the reserve. The estimated cost of materials to defend individual trees from cattle and rodents is five to ten dollars per tree, though if livestock prove determined to disturb protective devices, material costs might be twice this. Regulating grazing by cattle or other livestock so that unprotected seedling oaks can grow to maturity may be possible, but entails substantial risk of failure with considerable ensuing loss.
Lacking confidential information about university priorities and about the costs and benefits of various possible courses of action to affected parties, we are without basis to make firm recommendations. We will be pleased to participate in the development of an HRM program aimed at enhancing ecosystem integrity and productivity on the Academic Reserve.
Holistic Resource Management1
Holistic Resource Management is a process directed at meeting objectives in three realms:
- human life-quality,
- ecosystem yields, and
- natural resource conservation.
An underlying premise of HRM is that maintenance of ecosystem integrity preserves the value of land, by protecting its capacity to generate a sustainable stream of ecosystem benefits. Stanford's land endowment is unique. A conscientiously developed HRM program for the Academic Reserve lands can be a way to conserve and increase their value.
An HRM program can be designed to address Stanford planners' concerns about wildfire, livestock, and oaks within the context of more general goals, like protecting and enhancing the quality of soil, water, and air, maintaining diversity and dynamic stability in living populations, and increasing the amount of energy stored in the ecosystem and the rate at which energy is captured by it. An HRM approach also will likely rely upon a broad range of tools and techniques, which may include permanent and temporary fencing and stock watering facilities, wildlife attractors and habitat enhancers, prescribed fire, rangeland rest, disking, mowing, seeding and planting, intensive grazing by different livestock species, active herding and moving of animals, and user education. Perhaps most importantly, an HRM plan will entail frequent monitoring and adjustment. Allan Savory, the founder of HRM, emphasizes that a good practitioner always assumes that the management strategy currently being implemented is wrong.
Lying at the edge of the San Francisco-Oakland-San Jose metropolis, the Academic Reserve is more heavily impacted by external factors than are most of the places where HRM has been practiced. Hydrology, air quality, and surrounding land use, as well as a plethora of local, state, and federal regulations are largely beyond the control of university personnel. Here, where unanticipated outside influences can be common, and interventions by land managers are constrained in so many ways, the pattern of frequent, small-scale trial, assessment, and adjustment characteristic of HRM will necessarily be even more intensive than on a more typical site.2
Stanford land managers contemplate cattle grazing as one component of an HRM strategy. In grazing compatible with HRM principles, livestock are tightly controlled. Savory developed HRM after years of observing the role of wild African ungulate herds in the ecology of grasslands. His livestock management methods emphasize regulation of the timing of an animal's bite on forage plants. By simulating some of the conditions which existed in grassland ecosystems prior to the domestication of grazing animals, Savory aims to restore patterns of interaction closer to those which were present during the millions of years over which grasses and their herbivore predators coevolved.
In explaining how HRM works, Savory describes the process of overgrazing in minute detail. Animals graze certain plants, often leaving other nearby plants untouched. The bitten plants are stimulated to put on new growth, which offers more protein and energy, and less fiber, than older growth. Animals in the area graze the new growth preferentially. When livestock have prolonged access to an area, certain plants are overgrazed while their neighbors rest.
Herds of animals grazing continuously on relatively large plots usually both overgraze and overrest plants in the same area. This outcome may manifest as a mosaic of fairly extensive ungrazed and overgrazed patches, or it may take a more subtle form, dispersed among a variety of plants and species in a pattern difficult to discern with casual observation. HRM practitioners aim to prevent this result by concentrating stock in relatively small areas for brief periods. In these circumstances, animals graze all edible plants. They are then removed, and plants are permitted to grow undisturbed until they can be safely grazed again. This careful regulation of livestock is a defining quality of HRM, and is essential for HRM to fulfill its promise.3
Resources for HRM
If Stanford personnel decide to proceed with the development of an HRM program, its various components might qualify for financial subsidy or other assistance from state and federal agencies. The Agriculture Stabilization and Conservation Service offers grants of up to $3,000 per year for projects with resource enhancement objectives. California Division of Forestry makes $10,000 cost-sharing grants for qualifying land management projects, and through its Vegetation Management Program, and Forest Stewardship programs provides other types of technical support for grazing, burning, and other activities aimed at enhancement of wildlife and native plant habitat, or stimulation of forest and rangeland productivity.4
Wildfire in the foothills section of the Academic Reserve poses risk both to natural features, like native oaks, and to artificial features like research facilities and nearby homes. High values of fire-vulnerable elements in and near the reserve, and concerns of residents, researchers, and recreational users are reasons to be thorough in fire hazard reduction.
Characteristics of Grassfires
The grasses and low-growing annuals which populate much of the Academic Reserve are a dispersed fuel. Fire professionals term them "cool-burning" because they release much less heat per unit of land than forest or scrub.5 Grassfires are quick to spread, yet much less likely to "jump" firebreaks than fires in forest or chaparral.6 In oak woodlands they very rarely become canopy fires in the absence of substantial additional fuel, like brushy understory species or accumulated woody debris.7
Risk vs. Hazard
CDF personnel and other professionals with fire management expertise emphasize the distinction between fire risk and fire hazard.8 Risk is the chance a fire will occur, hazard is the magnitude of damage likely to result. The former can be of little consequence where the latter is small.
Areas like the Academic Reserve can be managed so that fire hazard is close to zero.9 The strategies for doing so are: eliminate concentrations of combustible material; provide firebreaks; maintain adequate fire-suppression response capability; and educate and regulate users.
In the foothills region, chaparral and other brushy understory plants, and woody debris are materials likely to fuel damaging fires.10 These are more dangerous when situated within or adjacent to woodland areas, or when they border buildings or trees near buildings. Regular removal of brush and woody debris from sensitive areas is key to fuel reduction in the foothills.11
Grazing and Fire
Grazing cattle can lessen the quantity of fuel which accumulates as a result of a single season's growth by the species they eat. Their suppression of the many annuals and perennials which they reject as food, and their impacts upon dead branches, snags and other woody debris-all of which are potentially troublesome fuels-are mostly limited to trampling.12, 13
Inadequately managed cattle can actually increase fire hazard by contributing to the spread of exotic annuals like thistle and mustard, which they refuse to eat.14 These opportunistic species readily colonize disturbed soils and places where other plants have been overgrazed. On the Academic Reserve they now grow in dense stands where cattle have historically congregated. This is especially true under canopies of large oaks and around previous watering sites. As noted above, accumulation of biomass from such plants within the driplines of mature trees poses fire hazards which experts consider more substantial than those presented by ungrazed grasslands.
Theoretically, cattle can be managed to diminish populations of thistle and other unwanted exotics, but we have yet to find specific examples of significant success in this endeavor. Some ranchers using HRM grazing regimes report that stands of bunchgrasses, primarily Stipa pulchra, are more vigorous and widespread as a result, but those we interviewed stopped short of asserting that weedy exotics have been substantially reduced in number or vigor.15
Grazing generates cash income for the university, and the presence of grazing lessee personnel may enhance public safety; however, only carefully regulated grazing to augment firebreaks or create low-fuel zones adjacent to sensitive facilities can contribute much to reducing risk of loss from fire. In some locations such grazing might meet HRM objectives better than disking.
Fire is a natural part of California's oak woodland ecosystem, and people have used fire as a management tool since pre-history. Native Americans regularly set fires, and European settlers continued this practice. Until the 1950's controlled burning remained an accepted means of improving grazing lands and destroying unwanted understory plants and detritus.16 During the next several decades fire suppression became increasingly common, especially near urban settlements. As a result, fuel accumulated and the risk of catastrophic wildfires increased.17 In addition, long-standing ecological relationships were disrupted.18
In recent years, fire has again become more widely accepted as a restoration tool. The capacity of fire to induce resurgence of native plant populations in degraded ecosystems is well-documented. In California managers of many Nature Conservancy preserves, state parks, and national parks, and a growing number of private landowners now employ prescribed burning in oak biomes to restore native species diversity and with it, ecological stability.19
Like wildfires, controlled burns leave a blackened landscape, which most people find ugly. Note, however, that fire professionals consider early summer the time when prescribed burns are relatively safe and most beneficial in terms of fire risk reduction.20 This coincides with a lull in the university calendar, and thus reduces negative impact on the Stanford community. Also, a program of rotational burning will in any single year entail much less extensive scarring than that which results from a major wildfire.
Local regulations allow burning on private lands between November 1 and April 30 as a method of forest management. Burning during other times of the year can be permitted for the purpose of wildland vegetation management. Burn plans require approval by Bay Area Air Quality Management District (BAAQMD) personnel and a fire permit issued by the local fire authority. Following approval, burning may take place on days designated by Bay Area Air Quality Management District regulators. Bay Area air quality standards are strict and there are a limited number of days each year when weather and air quality conditions make a prescribed burn acceptable. Costs of burning are borne by the landowner, and include fees charged by fire safety personnel, plus any damage to people or property resulting from a burn.21
Despite these constraints Bay Area land managers have been employing prescribed burns for the past decade to reduce unwanted biomass accumulation and to further restoration activities. BAAQMD personnel work closely with landowners to ensure that approved burns can take place, and people experienced in fire management at Annadell State Park, the BAAQMD, and U.C. Berkeley's Integrated Hardwood Range Management Program have all offered their expertise to assist in designing and implementing a program of prescribed burning for the Academic Reserve. Burn regulations are currently in flux, and proposed amendments appear likely to make fire an even more readily accessible tool.22
The placement of firebreaks and their specifications are largely beyond the scope of this report. Roads within the Academic Reserve provide some protection. Minimum requirements are established by law. Methods of fulfilling legal obligations or implementing additional measures to secure valuable natural or artificial assets can be assessed on the basis of their contribution to HRM objectives and their cost.
In many oak savannas and oak woodlands, disked firebreaks are considered sufficient manipulation of the landscape to reduce fire risks to acceptable levels.23 The current system of roads and disked firebreaks on the Academic Reserve meet the university's responsibilities as defined by local and state law.
Stanford planners are particularly sensitive to the concerns of owners and occupants of buildings and other improvements in and around the foothills portion of the Academic Reserve, and consider the value of these assets and the peace of mind of university community members to warrant extraordinary measures. Additional disking immediately adjacent to high-value homes and other facilities has been used to provide an extra margin of safety and peace-of-mind.
Disking, like fire, leaves the land scarred, and some university homeowners and Academic Reserve recreational users consider it a nuisance. In addition, disking accelerates erosion, kills beneficial fauna like snakes and lizards, obstructs the establishment of perennials, including oaks, provides the kind of disturbance which favors the spread of noxious species like thistle, and entails substantial expense. Because of its many drawbacks, especially its adverse affects on ecosystem integrity, disking is used with restraint in HRM programs.24
Mowing can prevent fuel accumulation with much less ecosystem disruption than disking.25 Mowing substantially diminishes fire risk even where trimmings are allowed to remain on the land, because it reduces the surface-to-volume ratio of the fuel. Cut grasses lying on the ground burn far more slowly than standing dry grass. When mowing is accompanied by removal of plant material, fire risk is lowered further, but care must be taken to preserve organic and mineral content of soils, and to provide adequate seed where annual plants are desired. In Contra Costa County, fire authorities consider a three-inch mowing of a fifteen foot-wide strip an acceptable fuel break on open space lands.26 If mowing is substituted for disking, and properly timed, it can be a means to encourage the displacement of exotic grasses and other annuals by native perennial bunchgrasses.27
Whether mowing is in place of disking or a supplement to it, marking oak seedlings in areas to be mowed with semi-permanent stakes so that mower operators can easily avoid them will reduce the risk that mowing will be an impediment to seedling recruitment. Mowing may even enhance survival and vigor of young oaks by lessening competition for moisture and by reducing shade from surrounding plants.28
Regularly mowing the open areas around the private residences along Junipero Serra Boulevard can reduce the potential of fire damage to these residences and provide reassurance to their occupants. The contractor currently responsible for disking firebreaks on the Academic Reserve has noted that mowing a 250-foot wide swath starting at the fence near Junipero Serra Boulevard, following the fenceline behind the houses adjacent to the Academic Reserve, crossing the extension of Frenchman's Road which enters the foothills, and following the fenceline around to Junipero Serra Boulevard will entail only modest additional cost.
Availability of fire-suppression personnel and equipment are generally beyond the scope of this report. Installation of emergency call boxes similar to those increasingly common along public highways might enable quicker response by trained fire-suppression personnel and otherwise contribute to the safety of people and property on and near the Academic Reserve.
User Education and Regulation
Currently open fires, including smoking, are prohibited in the foothills. Voluntary compliance and enforcement by a ranger working for the university and by users themselves have resulted in near universal adherence to this regulation.
Holistic Resource Management – Grazing Regimes29
Grazing livestock on the Academic Reserve entails costs and benefits. Which of these predominates depends upon the value of lease income, and of the positive and negative impacts of grazing upon the land. Because the cumulative effects of decades of grazing are impossible to isolate and precisely quantify, the calculation of net costs or benefits to date is at best a difficult undertaking. Cost-benefit analysis of contemplated future action is even more problematic. Historic grazing practices may be very poor basis for evaluating the impacts of grazing regulated by HRM principles. Ongoing disruptions of the larger environment in which the Academic Reserve exists make extrapolation of many aspects of past experience unsound.
Though cattle grazing has been implicated in the degradation of oak woodlands throughout California, recent research by HRM practitioners has shown that carefully controlled livestock can arrest and even reverse certain types of ecological degradation.30 Properly managed animals may provide valuable agitation to oak woodlands.31 By removing decaying material and old growth from perennials, livestock can stimulate regrowth, contribute to the development of stronger and more stable root systems, and improve water and mineral cycles. HRM proponents assert that a properly grazed ecosystem can become a sustainable oak savannah or woodland community. At the same time, both they and virtually all other qualified observers concur that a mismanaged grazing regime can push these often fragile habitats towards desertification.32
Cattle and other herbivores graze selectively.33 Overgrazing may be viewed as a result of inadequate recovery between grazings. Plants unable to replenish their energy stocks eventually die. Overgrazing can transform a diverse, stable plant community into a less complex and more brittle one by subtle extirpation of more vulnerable species. On lands like Stanford's Academic Reserve, overgrazing may be occurring even if a lush cover of annual plants returns each year.
HRM generally prescribes the establishment of several paddocks roughly equal in size, or more importantly, in livestock carrying capacity. Overgrazing occurs when animals linger too long on a site or return too quickly to it. Adequate recovery periods, proper sizing of paddocks, and appropriate stock density are essential to prevent overgrazing.
The recovery period for a given paddock is the time necessary for plants within it to replenish the energy lost by being grazed. Recovery periods depend upon weather, intensity of grazing, species mix, soil quality, presence of predators and pathogens, and a host of other factors. They can vary widely year-to-year and site-to-site. Over time they can become much longer or shorter.34
Once the recovery period has been estimated, grazing periods for each paddock can be calculated by the formula: grazing period = recovery period/(number of paddocks - 1). This formula presumes that paddocks are of roughly equal productivity. For example, a ninety-day recovery period for an area with six equal paddocks yields an eighteen day average grazing period. In general, slow plant growth requires slower moves among paddocks, and rapid growth calls for more rapid moves.
A livestock manager may want to move animals sooner than the end of the calculated period because the grass appears overgrazed, the stock need to be supplemented, or for other reasons; however, cutting the grazing period for one paddock reduces the recovery period for all others.
Paddock Size and Number
As more paddocks are available to a manager, the ratio of recovery period to grazing period rises. Increasing the number of paddocks also results in each paddock's being more evenly and fully grazed, because grazing impacts can be concentrated, and repetitive grazing with adequate intervening recovery is more likely to be possible. This lessens the risk of overgrazing, and increases utilization of range productivity.
For example, where the total grazing season is 180 days, and the recovery period is ninety days, a four paddock arrangement will allow each of two paddocks to be given a single thirty-day period of grazing, and each of two others to be given two thirty-day periods with ninety days of recovery between grazings. With the same grazing and recovery periods, a sixteen-paddock arrangement will permit every paddock to be grazed twice for six days. Though such calculations are first-order approximations, and adjustments to reflect rates of forage growth and other variables are ongoing, they illustrate clearly the advantage of increasing the number of paddocks.
Ranchers and other land managers commonly use electric fencing or other temporary restraints to restrict livestock to smaller paddocks within larger, permanently fenced areas. Electric fencing can be moved easily, and in many stock operations has proven economically sound. The flexibility with which electric fencing can be rearranged is well-suited to the HRM practice of accommodating seasonal and year-to-year changes in range productivity with altered grazing regimes. Though the lessee reported numerous difficulties arising from initial trials of electric fencing on the Academic Reserve for a few weeks during the 1993-94 grazing season, different deployment and monitoring arrangements might yet yield satisfactory results.
Stock density is the number of animals per unit of land. Though stock density might at first seem the factor most likely to be correlated with overgrazing, Savory and others have substantiated the claim that excessively long stays in a paddock, and insufficient paddock rest between grazings are often more critical.
HRM practitioners have noted a number of advantages to dense stocking. Animals graze a greater proportion of available plants and graze them more evenly, leaving fewer ungrazed or severely grazed. Distributions of dung and urine are more uniform. Animals move with greater frequency, stimulating them and providing a more constant level of nutrition. Tighter plant communities develop, and forage contains more leaf and less fiber. As a result of these and other factors, animal performance in general improves.35 However, these benefits come at some risk. Densely stocked animals pose danger of severe ecosystem damage if they remain too long or return too quickly. Net improvement of rangeland like the Reserve has yet to be shown.
Livestock operators engaged in HRM estimate stocking density on the basis of range carrying capacity. A stocking rate of 1:20 indicates that each animal will be allocated twenty acres of pasture. If the grazing season lasts 180 days, this level of grazing can only be sustained if each twenty acres can supply 180 animal-days of feed. Under this regime, each acre must supply nine animal-days. Thus, one-ninth acre (a square approximately seventy feet by seventy feet) must feed one animal for one day. A successful HRM rancher frequently assesses the condition of land and forage to determine whether these are consistent with existing and planned stock densities. Finding sustainable stocking levels is an on-going process of trial and error. Because of the complexity of multi-herd operations, some HRM consultants suggest that transition to HRM be made while running a single herd.35
Prior to the introduction of domesticated livestock, native grazing animals herded together to minimize their vulnerability to predators. They grazed intensively and moved often. Later, dogs and cowboys replaced predators and cattle replaced populations of native species. In modern times, predator extirpation has made herding largely unnecessary for livestock protection.
HRM advocates are accumulating evidence that herding improves the integrity of grazed ecosystems. Unherded animals often find favorite areas within a paddock. This can especially be damaging if the paddock is large, stock densities are low, and grazing is prolonged. Many portions of the Academic Reserve where mustard and thistle are dense today mark areas where cattle previously congregated and overgrazed. Often these will be only a few feet from stands of native perennials which are commonly ungrazed when stock roam large paddocks for long periods. Herding can ensure that animals graze all areas and all edible species within a paddock, and permits them to be used to compact soil or break down capped soils, and to trample down excessively heavy crops, such as mustard and thistle.
Herding can be accomplished by one full-time farmhand on a horse. At night animals can be left to roam or cordoned off with a simple lightweight fence (such as a piece of wire or cord wrapped around four trees).36
HRM consultants have noted that in areas like the Academic Reserve, opportunities for integrating horse owners and their animals into management programs abound. Current local horse boarding rates can be three to four hundred dollars per month. Horse owners may find it advantageous to assist with herding in exchange for boarding, grazing, and access privileges on the Academic Reserve.
Some ranchers have experimented with salt blocks, water, and baled feed to create herding impacts in specific areas. For example, a salt block placed in the center of a dense stand of mustard can cause animals to thoroughly trample the area. In this way, the mustard can be suppressed. However, it is important to move salt blocks at least twice daily to prevent damage from over-trampling. Again, the goal is to simulate natural patterns in which a densely packed herd moves quickly through an area. Achieving this effect is particularly important in areas which have already suffered from overgrazing.
On the Academic Reserve, the limited availability of water poses a constraint in paddock sizing and configuration. HRM practitioners commonly design paddocks so that borders radiate outward from a water source, permitting stock to access a single source from a number of paddocks. They also may use temporary watering facilities to herd animals. A variety of equipment for trucking water and providing animals temporary troughs is available, and the installation of permanent watering facilities in additional Academic Reserve locations may be justified.
Diversity of Animal Grazers
Introducing different species of grazing animals is a widely recognized method for achieving native plant diversity. The forage preferences, hoof and mouth physiology, and herding habits of animals vary.37 An integrated grazing plan that utilizes cattle, horses, sheep, goats, and even deer may foster oak regeneration, and control mustard, thistle, and tarweed populations more effectively than any scheme entailing cattle alone;38 however, managing multiple herds on the same land requires sophisticated expertise, and intensive monitoring.
Reintroduction of cattle as part of an HRM program will require visible changes to the Academic Reserve. Modest community education, like explanatory signs at reserve entrances, and written materials available upon request, may prove invaluable in recruiting community support and cooperation. Such actions seem particularly essential if the incessant stream of changes and adjustments characteristic of HRM are to be met with understanding and acceptance. In addition, community participation in various HRM activities may lower university and lessee costs, and enable program enhancements otherwise impossible.
The Academic Reserve is a brittle ecosystem, an area where decay is primarily driven by oxidation and weathering, rather than by decomposer organisms. In such ecosystems agitation plays an important role in preserving biological diversity and maintaining ecosystems in dynamic equilibrium. Cattle and other livestock can provide this agitation and can effectively remove certain types of biomass; however, employing grazing animals in the framework of HRM requires that they be managed so that their behavior closely mirrors that of natural grazers.
The combination of brief, intensive grazing and adequate recovery is an essential element of HRM livestock programs. Configuring the Academic Reserve into numerous small paddocks, and stocking them at high densities for short periods will enable university planners and lessees to begin to ascertain whether HRM yields results consistent with their objectives.
Implementation of the Vegetation Management Plan for the Academic Reserve (VMP) began ten years ago. The VMP authors proposed that the northern slopes of the reserve be divided into four paddocks, and that grazing be rotationally excluded from each of these for ten years in order to permit natural regeneration to occur. On southern slopes they proposed establishment of isolated protected sites for direct seeding of oaks.
The original framework of the plan has been repeatedly adjusted to accommodate conditions on the land, results of oak regeneration research at Stanford and elsewhere, and changing university priorities. Today there are at least two thousand young oaks scattered across the reserve. These include naturally seeded trees which escaped predation in areas from which cattle have been excluded, naturally occurring seedling and sapling trees individually protected from cattle in grazed areas, and trees planted under the auspices of the VMP throughout the area.
Under the conditions which have prevailed for the last decade, oaks on most parts of the reserve have grown too slowly to become capable of resisting cattle after only ten years. In many areas livestock have been excluded for less than half that duration. Where planting occurred recently with the expectation that livestock exclusion was to extend at least a decade into the future, young trees are especially vulnerable to depredation by grazing cattle. On the Academic Reserve and elsewhere in California, voles and other rodents have been found to pose a serious threat to juvenile oaks. Unless both naturally and artificially established seedlings and saplings are given continuing protection from livestock and rodents, much of Stanford's investment in oak regeneration may be lost.
Divers protection strategies are available. These include continuing cattle exclusion from large areas, controlling the timing of grazing to enable young oaks to recover after livestock have been removed, installing tree shelters around individual trees, and fencing single trees or groups of trees.
Cattle Exclusion Areas
Barring livestock from grazing young oaks is the surest means to prevent them from interfering with regeneration. Wholesale exclusion from the northern slopes of the reserve has enabled many seedling and sapling trees to grow without setbacks from grazing. Escaped animals were common in the early years of livestock exclusion, and repeatedly damaged seedling trees. During the most recent grazing season (1993-94) cattle have less often invaded the exclusion area, and lessee personnel have acted more promptly than in past years to recapture animals and return them to the leasehold.
The rest afforded land by livestock exclusion can encourage evolution of a diverse and stable plant community, and can be especially healing in an area where overgrazing has occurred; however, in ecosystems like those on the Academic Reserve, where a significant amount of decay occurs by oxidation and weathering, the beneficial effects of rest may decrease in value when the duration of rest is excessive and the beneficial agitation which stock can produce is forfeited.
Oak woodlands in California have evolved with agitation from periodic fire, and from cyclical browsing and grazing by diverse herbivores.39 Displacing these long-standing phenomena by fire suppression and sustained mono-species grazing has disrupted water and mineral cycles, brought wholesale shifts in types and quantities of biota, and contributed to the decline of oak ecosystems throughout the state.40 Also, in the absence of grazing, the risk of grass fire remains higher.
Strictly Timed Cattle Grazing
If cattle are removed from an area while moisture levels in the soil are still adequate to support oak seedling growth, grazed oaks may recover well enough to grow-albeit slowly-into mature trees.41 Many soils on the Academic Reserve are too dry to support seedling growth after April or May. Whether an HRM program can be designed both to reduce significantly the fire hazard from standing biomass which remains after grazing has ended, and to allow successful recovery by seedling oaks is yet to be proven.
Unprotected oaks that are grazed after water is inadequate to support growth will be unable to recover until the next growing season, when they will again be grazed.42 Only seedlings in the most favorable locations are likely to endure this cycle for more than a few years. Those that do will often remain stunted shrubs, unable to establish a central leader because the terminal buds of dominant branches are repeatedly removed by grazers.43
Plastic tree shelters placed around planted trees and other young seedlings have proven in some California locations to be a solid defense against grazing cattle and rodents. In addition, the microclimate within shelters encourages rapid growth and improves tree vigor, so that trees move beyond the reach of grazing animals and can withstand grazing pressure earlier in their lives.
Tree shelters fastened to a heavy T-post have been used experimentally in an area grazed by cattle at the U.C. Berkeley Sierra Field Station. In general, cattle ignored the shelters. Where cattle did rub up against the shelters, they proved resistant to damage. Protection might be improved by keeping the ground around sheltered trees clear of vegetation, to discourage cattle from even approaching them.44
Results of the fire of 1992 and experiments conducted by Magic personnel provide bases for assessing the fire hazard posed by shelters. Both types of shelter deployed on the Academic Reserve are flammable; however they burn much like a candle, slowly and at low intensity. Most of their heat is dissipated into the air. Though above-ground growth of enclosed trees may be consumed, root systems will likely be spared severe damage since the burning shelters raise the temperature of the ground very little. Wildfire may destroy the shelters, entailing replacement expense, but in a controlled burn, shelters can be removed beforehand and replaced afterwards without excessive cost.
For effective protection from grazing, four-foot shelters may be sufficient, but five-foot shelters are more secure.45 One heavy steel T-post is required for each shelter. Shelters of these sizes cost between two and three dollars each in the quantities required to protect identified vulnerable seedlings. These include about nine hundred planted sites and an equal number of volunteer trees. Posts cost approximately as much as the shelters themselves.
Though a T-post and tree shelter scheme may prove adequate defense against grazing animals and rodents, the behavior of livestock can be difficult to foresee. In situations where livestock repeatedly disturb shelters, or where trees have grown too bushy to be confined to shelters without destructive pruning, fencing may be required.
Fencing Individual Trees
In the savanna region, a design utilizing about twelve feet of sturdy building fabric wire and two T-posts has proven adequate to protect individual oaks from cattle. If necessary, this system can be enhanced with a wrap of barbed wire. The cost of materials to protect an individual tree in this way is about ten dollars. One drawback to this design is that it can encourage rodent activity near the base of the tree.46 Suppressing vegetation within the enclosure with mulch has reduced rodent intrusion, but entails additional cost.
In some places naturally or artificially established seedlings grow close enough to each other to make fencing groups of young oaks potentially less expensive than fencing individual trees. Securely fencing fifty trees on a half acre requires about eight thousand linear feet of barbed wire, one hundred fifty light steel T-posts, and four double-braced four-by-four wooden corner posts. Because installation of this type of fencing requires special equipment and skilled labor, the total cost per tree will likely be greater than that for fencing for individual trees installed by unskilled volunteer labor using simple tools and supervised by contractor personnel. Furthermore, fenced areas will continue to hold large quantities of annual plant biomass, increasing the chance that a fire which reaches such an enclosure will spread to all trees within it. Grazing between individually enclosed trees lessens this risk.
Ranchers have employed other schemes to protect trees in grazed areas. For example, four wooden pallets can be wired together to enclose individual seedlings. Though this technique can be implemented with minimum expenditure for materials, it will add substantially to the fuel load on the reserve, and will increase the risk of tree mortality resulting from ground heating in the event of fire. Another alternative entails cutting out the bottoms of fifty-five gallon drums and staking single drums around individual trees. This method appears inferior in effectiveness, and at least as costly as the wire cages described above.
We have outlined here some of the mechanisms by which the Academic Reserve might be managed to address issues of fire, grazing, and oak regeneration. Lacking proprietary information about university priorities, and about the costs and benefits of the different practices we have described to each affected party, we are without sufficient basis to offer firm recommendations.
We are grateful to have had the opportunity to contribute to native oak regeneration and to community understanding of the stewardship responsibilities and human benefits of the foothills portion of the Academic Reserve. We will be pleased to participate further in the development of an HRM program for the reserve.
The full name, affiliation, and telephone number of individuals referenced, and full citations for published and unpublished documents may be found in the Sources section which follows these notes.
- Unless otherwise noted assertions of fact in this section are based upon Savory and Bingham, 1990, and Savory, 1988.
- Work, pers. comm.
- Standiford, pers. comm.; Hastings, pers. comm.
- Buseman, pers. comm.; Wachtel, pers. comm.
- Adams, pers. comm.; Buseman, pers. comm.; Hastings, pers. comm.
- Adams, pers. comm.; Buseman, pers. comm.; Wachtel, pers. comm.
- Adams, pers. comm.
- Buseman, pers. comm.; Hastings, pers. comm.; Wachtel, pers. comm.
- Adams, pers. comm.; Buseman, pers. comm.; Wachtel,pers. comm.
- Edwards, pers. comm.; Work, pers. comm.
- Standiford, 1994.
- Examples include recent Yellowstone National Park, the Oakland hills, and Malibu hills fires.
- Standiford, 1994, citing others.
- Local examples include Annadell State Park, the Nature Conservancy's Santa Rosa Plateau Reserve, the East Bay Regional Park District, and others.
- Hastings, pers. comm.
- Open burning falls under regulation 5 of the Bay Area Air Quality Management District. Regulations and assistance can be obtained from Ray Peterson at BAAQMD.
- Buseman, pers. comm.; Hastings, pers. comm.; Peterson, pers. comm.; Wachtel, pers. comm.
- Buseman, pers. comm.; et. al.
- Savory, 1988.
- Gilpin, pers. comm.: McLaran, 1981.
- Gilpin, pers. comm.
- Gilpin, pers. comm.; Kephardt, pers. comm.; McLaran, 1981.
- Bernhardt, pers. comm.
- Unless otherwise noted assertions of fact in this section are based upon Savory and Bingham, 1990, and Savory, 1988.
- Bingham, 1990; Edwards, 1992; George, 1991; et. al.
- Edwards, 1992; et.al.
- Adams, pers. comm.; Bingham, 1990; Edwards, 1992; George, 1991; Hastings, pers. comm.
- Blunler, 1992; Edwards, 1992; Savory and Bingham, 1990.
- Research by M.R. George (1991) suggests that during periods of slower growth recovery periods typically range from sixty to ninety days. During periods of more rapid growth recovery periods can be as short as twenty to thirty days.
- Recommended by Adams, pers. comm.; Thompson, pers. comm.; Work, pers. comm.; Savory and Bingham, 1990; and Savory, 1988.
- Work, pers. comm.; Roger Ingram, an animal handling expert, consults and trains.
- Standiford, 1994; Edwards, 1992; George, 1991; et.al.
- Bernhardt, unpubl.; George, 1991; Standiford, 1994; Whitney, 1989.
- Edwards, 1992.
- Adams, pers. comm.; Bernhardt, pers. comm.; Blunler, 1992; Edwards, 1992; Hastings, pers. comm.; Kephardt, pers. comm.; McCreary, pers. comm.; Standiford, 1994.
- Adams, pers. comm.
- McCreary, pers. comm.; McCreary, 1993; McCreary and Tecklin, 1993.
- Experiments at the U.C. Berkeley Sierra Field Station were successful with four-foot shelters, but Tree Essential, a shelter manufacturer, suggests five-foot shelters.
- McCreary, pers. comm.; Adams, pers. comm.; et.al.
- Adams, Ted; Agronomy and Range Science, U.C. Davis, (916) 752-1011
- Bernhardt, Elizabeth; Principal, Phytosphere Research, (707) 452-6735
- Buseman, Rex; California Department of Forestry and Fire Protection (CDF), (415) 345-4091
- Clinic, Rich; Park Supervisor, Pleasanton Ridge Park, (510) 862-2963
- Ferri, Larry; Park Supervisor, Mt. Diablo State Park, (510) 687-1800
- Gilpin, David; Native Plant Specialist, Pacific Coast Seed Inc., (510) 463-1941
- Hastings, Marla; Restoration Ecologist, Annadell State Park, (707) 938-1519
- Ingram, Roger; Animal Handling and HRM Consultant, (916) 237-4563
- Kephart, Paul; Resource Management Specialist, Elkhorn Ranch, (408) 763-1207
- McCreary, Doug; Integrated Hardwood Management Program, U.C. Berkeley, (916) 639-2418
- Peterson, Ray; Bay Area Air Quality District, (415) 771-6000
- Standiford, Rick; Integrated Hardwood Management Program, U.C. Berkeley, (510) 643-5429
- Thompson, Rocky; Restoration Ecologist, Circuit Rider Productions Inc., (707) 838-6641
- Wachtel, Dave; Morgan Hill headquarters, CDF, (408) 779-2121
- Wills, Robin; Director, Santa Rosa Plateau Reserve, The Nature Conservancy, (909) 699-1856
- Work, George; Rancher and HRM Consultant, (805) 467-3233
- Bernhardt, E.A.; and Swiecki,T.J., 1991, Minimum input techniques for restoring valley oaks on hardwood rangeland, Report for CDF.
- Bernhardt,E.A.; Swiecki,T.J.; and Drake,C., Factors affecting blue oak (Quercus Douglasii) sapling recruitment, unpublished.
- Bingham, S., 1990, Where animals save the land, World Monitor, pp.34-40.
- Blunler, M.A., 1992, Some myths about California grasslands and grazers, Fremontia, 20:3, pp. 22-27.
- Edwards, S.W., 1992, Observations on the prehistory and ecology of grazing in California, Fremontia, 20:1, pp. 3-20.
- George, M.R., 1991, Grazing and land management strategies for hardwood rangelands, USDA Forest Service Gen. Tech. Rep. PSW-126, pp. 315-319
- Hall, L.M.; George, M.R.; Adams, T.E.; Sands, P.B.; and McCreary, D.D., 1991, The effect of season and stock density on blue oak establishment, USDA Forest Service General Technical Report PSW-126, pp. 312-314.
- Hall, L.M.; George, M.R.; McCreary, D.D.; and Adams,T.E., 1992, Effects of cattle grazing on blue oak seedling damage and survival, J. Range Management 45(5): pp. 503-506.
- Hart, R.H.; Samuel, M.J.; Test, P.S.; and Smith, M.A., 1988, Cattle, vegetation, and economic responses to grazing systems and grazing pressure, J. of Range Management, 41(4), pp. 282-286.
- McClaran, M.P., 1981, Propagating Native Perennial Grasses, Fremontia, 9:1, pp. 21-28.
- McCreary, D.D.; and Tecklin, J., 1993, Tree shelters accelerate valley oak restoration on grazed rangelands (California), Restoration and Management Notes, 11:2, p. 152.
- McCreary, D.D., 1993, Tree shelters protect oak seedlings from cattle, Oaks 'n' Folks, March.
- Savory, A., 1988, Holistic Resource Management, Covelo Island Press.
- Savory, A.; and Bingham, S., 1990, The Holistic Resource Management Workbook, Island Press.
- Standiford, R.B., 1994., The role of fire in California's oak woodlands, Oaks 'n' Folks, 9:2.
- Steffen, J., 1993, Study examines the heat of combustion of deciduous tree leaf litter (Illinois), Restoration and Management Notes, 11:2, p. 152.
- Whitney, S., 1989, The Pacific Northwest, A Sierra Club Naturalist's Guide, Sierra Club Books.