South Skyline Association

STATE OF CALIFORNIA - RESOURCES AGENCY
DEPARTMENT OF PARKS AND RECREATION
P.O. BOX 942896
SACRAMENTO 94296-0001

March 3, 1998

To: Castle Rock Advisory Committee Members
From: Castle Rock Planning Team, Dave Keck, Project Manager
Subject: Castle Rock State Park General Plan, Clarification of Planning Proposals

Through the resource inventory process for Castle Rock State Park, the California Department of Parks and Recreation planning team became aware that there are several areas in the park that have highly significant geologic features and plant and animal assemblages. Because of these findings, the team has proposed natural preserve status for an area of approximately 2,000 acres within the King's Creek and upper San Lorenzo River watersheds at Castle Rock State Park. This paper presents the legal definition of a State Park Natural Preserve, the features in the park we feel justify natural preserve status, and background on potential impacts to the area from off-trail use. It is important to note that public access into the proposed natural preserve would continue via official trails. These will adhere to the department's criteria for trail development in order to cause the least impact to the environment.

Definition of Natural Preserve Classification

(PRC 5019.71, Div. 5, Chapter 1, Article 1)

Natural preserves consist of distinct areas of outstanding natural or scientific significance established within the boundaries of other state park system units. The purpose of natural preserves shall be to preserve such features as rare or endangered plant and animal species and their supporting ecosystems, representative examples of plant or animal communities existing in California prior to the impact of civilization, geological features illustrative of geological processes, significant fossil occurrences or geological features of cultural or economic interest, or topographic features illustrative of representative or unique biogeographical patterns. Areas set aside shall be of sufficient size to allow, where possible, the natural dynamics of ecological interaction to continue without interference, and to provide, in all cases, a practicable management unit. Habitat manipulation shall be permitted only in those areas found by scientific analysis to require manipulation to preserve the species or associations which constitute the basis for the establishment of the natural preserve. (added by Stats. 1978, Ch. 615)

How the proposed natural preserve area at CRSP meets this classification

1. Endangered animal species and their supporting ecosystems:
   Wildlife inventories of Castle Rock State Park have produced a list of several special species that occur or potentially occur at the park unit. Among these are four species that have official federal or state listing under the federal Endangered Species Act or the California Endangered Species Act. These include the marbled murrelet (federal listed threatened, state listed endangered), California red-legged frog (federal listed threatened), peregrine falcon (federal listed endangered, state listed endangered), and steelhead trout (federal listed threatened). Supporting ecosystems for listed species within the proposed natural preserve include: old-growth coastal coniferous forest (marbled murrelet nesting); the upper San Lorenzo River aquatic and supporting riparian community required (spawning steelhead trout); and cliff habitat (peregrine falcon nesting). Habitat within the park for California red-legged frog is presently undetermined; however it is expected that most potential habitat in the park for this species occurs within the proposed natural preserve.
   
   
2. Representative examples of plant or animal communities existing in California prior to the impact of civilization:
   Redwood Forest - A stand of large-diameter, old-growth coastal redwood forest occurs along an unnamed tributary to King's Creek, within the boundaries of the proposed natural preserve. This is a prime example of upland redwood forest that occurred in the Coast Range prior to Euro-American civilization.

   Knobcone Pine Forest - Knobcone pine forest been designated as a rare plant community by the California Department of Fish and Game, Natural Diversity Data Base Nearly. Nearly all of the knobcone pine stands occurring within the park unit have been included within the boundaries of the propose natural preserve. One small section of a knobcone pine stand, occurring in the Castle Rock Trail Campground, is outside proposed preserve boundaries.

   Black Oak Woodland - Black oak woodland is relatively rare in Santa Cruz County. The largest stand of this plant community is found in Castle Rock State Park. The acreage of black oak woodland included in the proposed preserve is between 55 - 65 percent of the total in the park. The entire woodland was not included in preserve boundaries in order to continue to provide opportunities in the Castle Rock Ridge area for low impact rock climbers. However, protection for the black oak woodland within this zone, as well as within the proposed preserve, is a high resource management priority.
   
   

3. Geological features illustrative of geological processes:
   Tafoni rock features that occur in various location throughout the park. These tafoni formations are derived from a process called "cavernous weathering." In this process, mildly acidic rainwater penetrates the sandstone rock and gradually dissolves the calcium carbonate that cements the sand grains together. In the dry season, water in the rock evaporates, carrying the dissolved calcium carbonate to the surface, where it precipitates out, forming a hard "dura-crust" on the outside of the rock. Because the cement is now missing from inside the rock, the sand grains will collapse to form caves. By a repetition of this process through time, the caves grow larger. Tafoni formations are rare and found in only a few regions of the earth with a Mediterranean climate. Tafoni formations in the Lion Caves and other areas of the proposed natural preserve are in relatively pristine condition, as opposed to those outside proposed preserve boundaries. Rocks with tafoni outside of the proposed preserve have been subjected to visitor use for several years; many are riddled with climbing bolts, moss has been removed from rock faces, and the vegetation and soils around outcrops has been disturbed. A Climbing Management Plan will be developed for the park unit that regulates climbing activities to ensure that tufoni formations will not be damaged or destroyed. It is recommended that climbing be prohibited in the proposed natural preserve.

Concerns regarding the area proposed for natural preserve classification:

Special Species
he marbled murrelet (federal listed threatened, state listed endangered) is a small sea-bird that nests in old-growth coastal coniferous forest. Marbled murrelets that are found in the Santa Cruz Mountains are part of the southern-most of three populations occurring in California. This population is estimated to number approximately 600 - 1,000 individuals. Demographic studies throughout its range show that this species is declining at a rate of from 2-4 percent annually; however it is conceivable that the actual decline may be 2-3 times greater than that (i.e., 4-12 percent annually). Logging of old growth coastal coniferous forest is the greatest reason for the decline, however gill netting, oil spills at sea, and predation are also factors. Ravens, crows, Steller's Jays and great horned owls have been documented to prey upon marbled murrelet eggs and nestlings in nesting habitat. These predators are associated with "edge" habitats. Edge habitat occurs naturally where two different plant communities join each other. Edge habitat is formed artificially when a disturbance such as a road or other development is constructed within an otherwise continuous plant community, or where an area is subjected to logging and other land use changes. When this occurs, edge-related species have access to new areas where they compete with, or prey upon, species that are found in the continuous, or interior, habitat. The enormous global increase in edge communities from human activities has resulted in population increases of many edge species. Current research indicates that marbled murrelets may have an affinity for nesting in old-growth conifer forests near the forest stand edge. Marbled murrelet's reproductive biology and behavior limits the species to only one potential offspring per nesting pair per year, far less than that of edge-related predators such as ravens and Steller jays. Habitat reduction and increases in predator populations seriously jeopardize the marbled murrelet in upland habitats.

One concern for the area proposed for natural preserve status is that visitors off trails will create volunteer trails in otherwise continuous habitats, thereby increasing edge habitat. This could bring increased numbers of edge-related predators into closer contact with nesting murrelets, as well as with other special species. This would greatly increase the potential for adverse impacts on special species. With off-trail visitor access, the location and number of unplanned trails cannot be controlled.

Another concern is the direct impact that humans have on wildlife, especially special species. Rangers and researchers documented the decline of wildlife sightings along park trails in the mid-1970's, a period when visitation was rapidly increasing. Declines were attributed to the flight behavior of many species as a response to the presence of humans. The effected animals are quite often displaced into areas that are marginal for survival because of behavioral interactions within their populations. With the predicted growth of nearby metropolitan areas, the demand for public access into natural areas is also predicted to grow. The desire to get away from the crowds and explore off-trail areas will be increasingly tempting. By allowing off-trail access, human-induced displacement of species that are sensitive to disturbance could increase in the very areas that have the greatest habitat value.

In addition to threatened and endangered species there are special species that are either candidates for listing, or are of special concern to wildlife agencies because of population trends or habitat loss. Species in this category that have been identified at Castle Rock State Park, or that potentially occur there, include Cooper's hawk, sharp-shinned hawk, golden eagle, long-eared owl, black swift, Vaux's swift, purple martin, yellow warbler, loggerhead shrike, western pond turtle, California horned-lizard, California tiger salamander, Townsend's big-eared bat, pallid bat, western mastiff bat, ringtail, and mountain lion. The proposed natural preserve contains variety of habitats used by these species. Concerns regarding habitat fragmentation and associated problems of edge-related predators and direct human disturbance apply to many of these species.

Steelhead trout is an anadromous fish that spawns in the San Lorenzo River, within park boundaries. The chief concerns for steelhead within the park are 1) protecting their spawning beds from siltation caused by accelerated erosion, and 2) maintaining water quality. The accelerated erosion of volunteer trails located on steep slopes with unstable soils that occurs during heavy rainfall events may impact both spawning habitat and water quality (see below: soil, vegetation and water resources). While the department cannot control natural events like landslides that are a function of slopes and saturated soils, it does have the potential to effectively control trail location, and therefore accelerated erosion. In the natural preserve, it is proposed that visitors stay on official park trails that are planned and developed using department criteria for placement to avoid impacts to special species.

Soil, vegetation and water resources
Visitors to Castle Rock State Park immediately become aware of the impressive scenic vistas in the park. These vistas are provided by the steep topography within the park unit that, on clear days, allows one to see to Monterey Bay and beyond. However, the steep slopes and potentially highly erosive soils that blanket them also limit the amount of development that can occur in the park.

Determinations of limitation and suitability ratings for various uses of specified soils in the park are based on a large number of soil properties and qualities observed in the field and through laboratory testing performed by the U.S. Department of Agriculture - Soil Conservation Service (SCS). Some of the factors used to develop criteria include slope, wetness, flooding, texture of the surface layer, depth to bedrock, kind of clay minerals, and parent material. Based on these and other criteria, soil suitability and limitation ratings have been developed for each category of land use. Resource inventory data shows that most soils at Castle Rock State Park, including those of the proposed natural preserve, have SCS soil ratings listed as "severe." A severe rating means that soil properties and/or site conditions are so unfavorable for the intended use (e.g., absorption fields, roadfill, roads, picnic areas, paths and trails, or campgrounds) that limitations can only be offset by a major increase in construction effort, intensive maintenance, special design, limited use, or by a combination of these measures. This often requires costly, major soil reclamation work.

There is currently ample evidence in the park of unofficial volunteer trails in varying stages of gullying because of their location on steep slopes bearing unstable soils. The erosion of these soils results in the following damage:

	Soil removed by erosion frequently ceases to be of value to native plant communities; the remaining soil, denuded of surface soil, is greatly decreased in productivity.
	The loss of rainwater that is channeled down gullies does not enter the soil for possible use by vegetation; this channeled water erodes soils in and adjacent to the gullies, and enlarges the gullies.
	Soil removed through erosion may be deposited in streams such as the San Lorenzo River and KingĄs Creek, thus reducing in-channel water storage capacity and increasing the likelihood of flooding and bank erosion. Siltation also impacts spawning beds for steelhead trout as well as habitat for other aquatic animals and invertebrates. Colloidal clay particles in the water column impact water quality and may have a direct adverse effect on aquatic organisms.

Disturbances in soil surface caused by volunteer trails also creates conditions favorable for invasive exotic plant species. When volunteer trails are formed within continuous plant communities, disturbed soils allow invasive exotic plants to penetrate into areas they were formerly incapable of occupying. For example, German ivy, an invasive exotic plant, has a devastating effect on riparian communities. This vine uses existing plants for structural support. Its leaves intercept sunlight, shade out the native vegetation and kill it. Impacts to the native plant community structure and composition negatively affect the animal life that is dependent upon native habitat for cover and sustenance. Eradication of these weeds can be very costly, especially when native plant restoration and maintenance is necessary.

Esthetics
Some sections of park unit, such as the Lion Caves and Castle Rock Ridge areas, have a combination of landform and micro-site conditions that allow a luxurious blanket of moss to cover the surface of small rocks on the ground as well as entire faces of some rock outcrops. In a pristine state, such as occurs in portions of the Lion Caves area, this, in combination with the unusual tafoni formations, is highly scenic. During the wet season the attachment of moss to the rocks is very fragile and dislodges with light foot traffic. In order to preserve this unique setting, volunteer trails in the Lions Caves area should not be allowed. Because the sport of rock climbing impacts the moss shrouds that cover rock faces, it should also be prohibited in this area. Public access should be provided to the area in order to furnish visitors with an opportunity to experience and gain an appreciation of its unique character. It is recommended that this access be provided by way of an official park trail, to be planned using approved criteria for trail placement to result in minimal impacts to the area.

Natural Preserve Boundaries

The boundaries of the designated area would follow existing roads, trails, river and stream corridors and state park boundaries, to create a practical management unit. The size of the proposed natural preserve includes known locations of sensitive plant and animal species or habitat and their supporting ecosystems.

The proposed natural preserve area will be roadless. Existing trails are located along ridges providing access for ranger patrols and public access to trail camps and scenic vistas. These trail routes are for hiking and pedestrian use only and are managed for minimal environmental impact. These trails will remain and new trails may be considered in the natural preserve where needed to meet interpretive objectives.

Alternatives to the proposed size and location of the natural preserve that were evaluated include a smaller watershed area and two separate preserves for the Lion Caves and Kings Creek Canyon wildlife habitat. These are still viable alternatives, but do not afford the desired level of resource protection. Public concerns for the proposed size of the preserve reflect a desire to maintain off-trail access and to allow for new climbing opportunities. The planning team believes that this would lead to an increase in recreational uses at Castle Rock State Park and more demand for trails development than would be appropriate for these natural areas.