TRENDS IN LAND USE PLANNING AND CONSERVATION BIOLOGY
For California, 1992 was a year of conservation planning. Housing starts declined and commercial properties suffered high vacancy rates for a second year. This stall in the economy created an opportunity for proactive planning of land-use at the county and regional level. As such, there has been a tremendous need for information and education on sensitive species, sensitive habitat, and wildlands management. This need is particularly true for southern California hardwood rangelands, where over 23 species of vertebrates may be listed as endangered in the next two years. The IHRMP was involved in a number of issues, including: 1) providing policy panels and local planners information on sensitive species conservation; 2) developing standard survey methods to describe the occurrence of sensitive species and habitats; 3) educating landowners on environmental laws and endangered species.
In 1992, the first steps were taken to divide the management of the state's biological resources into 10 bioregions: the North Coast, Klamath, Modoc, Sacramento Valley, Sierra, Bay and Delta, Central Coast, San Joaquin, South Coast, Mohave Desert, and Colorado desert. Boundaries are flexible and were designed to address specific issues in conservation. As such, they are likely to change over time, reflecting the geographic features which best define specific problems in resource management. This new flexibility means more participation of all levels of government in resource policy decisions. More important to the IHRMP, information needs will be decentralized. Cooperative Extension may play a far larger role in information management in response to these regional situations. Counties are more likely to respond to landowner needs; applied research and outreach will be necessary to help resource agencies define management options. In the south coast, the IHRMP has already begun to study how wildlands are being altered by land development, and is focusing on the way animals respond to these habitat changes. Evolving topics of research range from the response of individual animals to human disturbance to landscape-level fragmentation of species distributions.
The Natural Heritage Program of the California Department of Fish and Game, using the Natural Diversity Database, has taken the lead in identifying sensitive biological resources in each region. Their first objective is to define the geographic patterns of sensitive resources. The most active ecoregion is South Coast, where over 80 persons have contributed information. The critical question is how these data will be applied to the state's plans for preservation. IHRMP academics are currently attempting to develop standards for preserve design and management; however, there is a tremendous need for information and policy development because many preserves will be developed on private lands. The southern California IHRMP specialist currently is a member of the Southern California Association of Governments (SCAG) Open Space Task Force, charged with developing criteria for preserve design and protection of biological resources.
A more focused management effort has been undertaken in the coastal sage scrub vegetation of the hardwood rangelands. Controversies about land development in this habitat prompted the State Resources Agency to develop the Natural Community conservation Plan (NCCP). This plan is designed to expedite solutions to land management problems through regional planning. A plan was developed for coastal sage scrub, a vegetation type that covers much of the hardwood rangeland in southern California. Implementation of the plan will demand a tremendous amount of new information, policy decisions, and new techniques for biological surveys. Outreach by the IHRMP in this area was reactive for most of the spring and summer, conveying information to county supervisors, planners, consultants, and landowners. Cooperative Extension staff took part in the development of survey techniques for San Diego and Riverside counties, and reviewed methods suggested by the scientific panel.
In addition to state actions, there are county-based efforts on biological conservation which are attempting multiple species management plans. San Diego, Riverside, and Orange counties, as well as Camp Pendleton (US Marine Corps), have begun to assess their resources and plan for a system of reserves. Joint powers agreements between these agencies and other local governments appear to be the grass-roots equivalent to the NCCP. IHRMP staff have been active in developing protocols for information acquisition in both San Diego and Riverside counties and have a wildlife habitat demonstration plot in Orange County. The federal government, through the US Fish and Wildlife Service, has begun to supply information on endangered species and sensitive habitat distributions. The IHRMP has agreed to work with them to evaluate data quality.
The Santa Rosa Plateau remains the best example of integrated resource management in southern California. The Plateau has a Nature Conservancy preserve as its focal point, surrounded by multiple use lands and rural housing. The IHRMP has held a number of workshops with environmentalists, planners and landowners and is close to developing a system of wildlife habitats that encompasses the preserve, a series of corridors and easements, and network of private lands managed for wildlife enhancement. The opportunity for integrating resource management among the Nature Conservancy, government agencies, and private individuals is outstanding.
Biological assessments continue to be a problem for local governments. Questions about the adequacy of proponent-prepared environmental assessments have prompted agencies and local governments to seek the equivalent of scientific peer review on environmental projects. Planners endorse the concept of peer review because they set professional standards for conduct. Land developers, while unhappy about the loss of control, recognize the benefits of streamlining the review process through standardization.
The IHRMP is participating in a pilot project on CIS monitoring of the biological resources at the wildland/urban interface with the Urban and Environmental Outreach Program (UEOP) at UC Riverside. This is designed to give county planners almost instant assessments of the biological issues associated with development of any parcel within their jurisdiction. Inventory and retrieval systems for spatially based information are the crux of the system, which will allow county planners to ask for the specific kinds of biological reviews. Project proponents would receive from a potential conflicts between their development and the regions biological resources, thereby focusing environmental discussions. In turn, new information from the project surveys would be incorporated into the biological inventory system.
Oak Regeneration and Restoration
Even before the IHRMP was established in 1986, it has been recognized that poor natural regeneration of several native oak species is, potentially, a serious threat to their long-term sustainability in California. A number of IHRMP research projects have focused on identifying and understanding the factors responsible for poor oak recruitment. While these studies have clarified some of the specific causes of poor oak regeneration, this research has also demonstrated that there is no single or simple explanation. Instead, the causes are complex, varied, and often site specific.
Tree Shelters Protect Oak Seedlings from Cattle
One of the major obstacles preventing successful planting and establishment of oak seedlings on rangelands is browsing by herbivores such as rabbits, deer, and livestock. While screen cages have been used to protect seedlings from rabbits and deer, protecting seedlings from cattle has proved much more difficult. Cattle often nip off or trample unprotected oak seedlings. This damage is especially great in the late spring and early summer when other vegetation is drying up and young seedlings may be the only green plants around. Cattle also tend to pull up, stomp, or bend mall protective cages or shelters. Consequently, to date, it has generally been recommended that cattle either be excluded from oak seedling planting areas by building small cattle-proof exclosures, or kept entirely out of pastures where seedlings are planted, Unfortunately, these approaches have significant costs associated with them. Small cattle exclosures are expensive to build and maintain. And eliminating livestock from large pastures for the five to ten years it can take for oaks to grow big enough to be resistant to browsing, takes land out of production, thus eliminating revenues.
This past year, an alternative approach—using tree shelters to protect individual seedlings in grazed pastures—was evaluated in a research project at the Concord Naval Weapons Station. Tree shelters are tall, slender, double-wall plastic tubes that protect seedlings from physical injury and create a greenhouse environment favorable to more rapid growth. Those used in this study were four feet tall and were held in place using six-foot tall metal T-posts.
The results indicated that tree shelters can be effectively used to protect individual seedlings from cattle. None of the 52 tree shelters in the open were seriously damaged or rendered ineffective. In addition, seedlings inside tree shelters tended to grow rapidly. After one year from acorns, 58% of the seedlings inside tree shelters were alive, and average height was over 20 inches, with a sizeable percent growing over three feet.
While protecting individual seedlings with tree shelters is not cheap—it costs approximately $5 for a four foot tree shelter and a metal fence post—it is certainly less expensive than building fences around planting spots. These devices also have the added advantages of protecting plants from insects and rodents, facilitating weed control, and promoting growth. They therefore appear promising as a method for successfully protecting plants in areas where livestock browsing is a concern.
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This past year, a large state-wide project was initiated to evaluate how various environmental and management factors influence the ability of oaks to regenerate. Its primary goal is to identify factors critical for natural regeneration success, and determine how these factors vary from location to location. It is hoped that this information will provide guidelines for determining where regeneration is likely to occur or not occur, and prescriptions for enhancing natural regeneration where it is inadequate.
Another focus of regeneration efforts of the IHRMP has been to develop practical, low cost techniques for artificially establishing oaks where they have either been removed or are not regenerating in sufficient numbers to sustain populations. This research has been fruitful in that techniques have been identified and tested which result in high seedling survival and vigorous growth. These techniques are continually being refined to help develop more effective procedures suitable for large wildland plantings.
This past year, a number of studies evaluated various site preparation and seedling maintenance approaches, including augering, fertilization, top pruning, weed control, and various methods of protecting seedlings from animal damage. This research has indicated that there are a number of ways to increase the survival and growth of both acorns and seedlings planted in the field. Several studies have shown that one of the most critical factors necessary for establishing oaks is to control competing vegetation. Weeds not only compete with oak seedlings for limited moisture and nutrients, but create a habitat favorable to insects and rodents. High populations of these animals can, in turn, cause heavy acorn predation, herbivory and/or damage to roots. A study this past year indicated that the size of the weed-free areas around seedling planting spots can dramatically influence field performance. Seedlings planted in four or six foot diameter cleared areas had much higher survival and growth than those growing in two foot circles or in areas where no weed control was provided.
Animal damage has also repeatedly been shown to be a major factor limiting natural regeneration and adversely impacting efforts to artificially plant oaks. Several ongoing projects have been evaluating the efficacy of various seedling protectors in reducing damage from animals. These studies have indicated that a relatively new type of protective device called a tree shelter is particularly effective in preventing damage from a wide range of animals, including livestock (see sidebar).
Other techniques for improving the field performance of oak seedlings are also currently being evaluated. A recent study examining augering and fertilization prior to planting has shown that both of these practices can increase early growth of seedlings. Augering breaks up hard, compacted soil, allowing easier downward penetration of roots, and greater access to moisture available at deeper depths. Fertilization assures adequate nutrient availability, resulting in accelerated height and diameter growth. In another study, top pruning of seedlings at time of planting (to bring the shoots more into balance with the roots) also resulted in greater growth during the first three years.
As knowledge about how to grow and plant seedlings has expanded, the following question has arisen: How much genetic variability is there within different oak species, and how far away can seedlings be planted from where the acorns are collected? This question may be critical because experiences with other tree species have shown that offsite planting can, on occasion, have disastrous consequences. For instance, some conifers planted far from where their seed was collected have grown poorly or even died because they were not adapted to conditions in their new environment. At present, however, we know very little about how much genetic variation there is within different species of oaks or how far oaks can be moved without risking poor performance. Several projects are attempting to answer this. One is examining genetic markers within oak tissues to determine how much variability there is within populations. Two other studies are examining how well seedlings grow in different environments. In one, acorns were collected from a wide range of latitudes and elevations and then planted in "common garden" sites in both Yuba and Mendocino counties. These seedlings will be monitored for a number of years. How well they survive and grow at these sites should provide insights into how different seed sources (families) perform in different environments. This will, in turn, assist in developing planting guidelines and establishing seed zone maps for those species that will be widely planted.
As mentioned above, the ultimate purpose of testing and evaluating different regeneration techniques is to develop practical, low cost approaches, suitable for wildland plantings. Recently a number of restoration plantings have been undertaken using techniques developed by the IHRMP and others. At the Sierra Foothill Research and Extension Center, a four-acre field previously cleared of oaks for range improvement (removal of trees and shrubs to promote grass growth and forage production) was planted with over 1400 oak seedlings and acorns. While this planting has incorporated a study to evaluate different types of planting materials and site preparation methods, its primary goal is to restore an area to its natural vegetation.
Another planting at the Concord Naval Weapons Station is helping to restore valley oaks on lands where most of the original vegetation was also removed. Using techniques previously developed, this project resulted in many 3-foot tall saplings at the Station in less than a year after the acorns were collected. A similar, even larger scale, project is planned for Camp Roberts in Monterey County. The IHRMP has also worked with other organizations, including The Nature Conservancy, to promote oak restoration and improve its success.
While large scale wildland plantings are critical for sustaining the oak resources at the landscape level, there is also a need to develop specific recommendations for restoring oaks on disturbed sites. Increasingly, urban development in oak woodlands is resulting in tree removal. Mitigation for these losses often requires on-site planting of oak seedlings. Unfortunately, these sites may be extremely difficult to plant since they are on engineered slopes that have either been graded or filled and compacted. To evaluate several alternative approaches for establishing native oaks on such difficult sites, an IHRMP project funded by the International Society of Arboriculture is currently underway at a development in Contra Costa County. This project is evaluating how different stock types (sizes and ages of seedlings) and different planting methods, will affect field performance. The results should provide recommendations for mitigating losses and restoring oaks in development areas.
