BIG BEND The Impact of Human Use Upon the Chisos Basin and Adjacent Lands NPS Scientific Monograph No. 4

Basin

The major recommendations for the Chisos Basin are directed toward preventive control of impact and rehabilitation for those areas already impacted, Since the major form of activity centers around exposing the visitor to the unique landscape, effort must be made to provide this service in the smallest area possible and with the least effect upon the vegetation. Definitely, no further plans should be considered which will expand the impacted areas. Instead, a vigorous rehabilitative, revegetative program should be instituted to provide a more natural vegetation in both the Upper and Lower Basin complexes.

Since there is presently no Mountain Woodland Interpretive Program, one should be provided to offer a broader educational opportunity to the visitor. With the suggested reduction of visitor lodging and personnel housing in the Upper Basin, the present Ranger Station location would provide an excellent site for an interpretive center with a panoramic view of the basin and with close access to the woodland. From this center the visitor would have easy access to dining, auto, and food supplies, not to disregard Ranger Station services and easy access to several potential self-guided nature trails of varying lengths.

It is highly recommended that a program be instituted to phase out the use of horses on all basin trails. This unnatural population is creating or contributing to every major form of vegetation impact which was investigated. The decay of the trail system and the spread of Sorghum halpense are definitely attributable to their activity. One cannot expect to maintain any near-natural form of vegetation along the trails in the basin if the use of horses is permitted to continue.

Accompanying the vigorous rehabilitative-revegetation program, human walking and exotic or introduced species must be controlled. With a program to eliminate mountain lodging and unnatural horse populations, the only remaining areas of concern would be the campgrounds. Because the campgrounds are confined to more isolated areas, their effect is more restricted than the other two, hence walking and alien introductions can be more readily controlled.

Basic rehabilitative revegetation program

This program should be initiated as soon as the groundwork can be laid. The immediate plan should take advantage of the climatic cycle which is presently supporting significant reproductive advancement of the woodland trees. The program will probably require 15-20 years to shift the present man-influenced xeric condition to the native woodland vegetation. The major emphasis should be directed toward all impacted areas of the Upper and Lower Basin complexes. The area between the complexes should also be given attention, especially along those slopes with trails. The more extensive erosion sites along the roadcuts and trails should also receive attention, as well as abandoned impact areas.

The program should be under the direction of a Park Biologist who has ecological training and contact with consulting plant ecologists, soil geologists, and other pertinent consultants with extensive experience in regional woodland dynamics. Records of all procedures and plantings should be maintained for periodic evaluation and future reference. In the early phase of the program, moisture supplementation may be required for the trees and shrubs; however, as the program progresses natural vegetation will become established and supplements will not be required.

The basic program would entail the following steps: (1) The preparation of the bare or impacted site for vegetation establishment by controlling human walking, providing near-natural runoff moisture, adding sufficient rocks to slow runoff, and providing large, temporary rocks which can cast shade on newly established seedlings during the summer months, etc. (2) An annual collection of Bouteloua curtipendula fruits should be made in the basin along the pipeline scars, etc., to sow in the prepared impacted areas. This planting should be done 2 or 3 years in advance of the woody plantings to aid in site stabilization. (3) An annual surveillance should be made of the basin for sites of extraordinary Evergreen Woodland Formation species reproduction from which seeds, cuttings, and small seedlings for transplanting may be taken. The biologist and consultant should make this evaluation to prevent excess removal from the source. An example of an area which exhibits high reproduction presently is the northern end of the Boulder Meadow circle (Table 17). (4) To ensure success of the program, the seeds, cuttings, and seedlings should be propagated in a temporary starting nursery established in the area around the water barrel. Here the many plants can be furnished water to promote more rapid and controlled growth and ensure establishment when transferred to the rehabilitation site. Once a sufficient supply of plants is provided, the nursery can be phased out with no undue impact to this area and in the process it can rehabilitate the area around the water barrel. Most of the shrubs can be propagated from cuttings rooted in auxin-supplied solutions and soil culture.

The suggested trees for planting are Pinus cembroides, Juniperus deppeana, Quercus grisea, and Q. emoryi. Suggested shrubs are Rhus virens, R. aromatica, Garrya lindheimeri, Cercocarpus montanus, and Ceanothus greggi (desert ceanothus). Nolina erumpens and Agave scabra are suggested succulents; however, Dasylirion leiophyllum could be judiciously used as a supplement. Grasses which could be planted after the Bouteloua curtipendula stabilization period are Muhlenbergia emersleyi, Piptochaetium fimbriatum, and Stipa spp. (needlegrass). These should be transplanted as clones and supplemented by the sowing of fruit.

Exotic and introduced species program

The emphasis of this program should be to control and eventually eradicate all exotic and introduced species from the Chisos Basin, especially in the man-influenced areas. A second aspect of the program should be to alleviate all sites which support such populations. These are frequently erosion sites along roads and trails and moist areas around water hydrants. The third area of concentration should be to control or alleviate the means of introduction. Since several of these are directly related to National Park Service, Chisos Remuda, and National Park Concessions maintenance and operation, this can be quite readily controlled.

Presently, there are several introduced populations which should be removed from the basin. The Cupressus arizonica trees in the main campground and Campfire Circle should be replaced with native trees and shrubs listed in the basic revegetation program. The cypress trees are not native and falsify the vegetation at the expense of native trees. Since Larrea tridentata is not a common natural species in the Lower Basin, all plants in the campground, along the Lower and Upper Basin roads, should be removed. Those which occur in the transported soils of the old road scar and pipeline scar should also be removed. They all produce great numbers of seeds which may find suitable germination sites and dominate the unnatural area for many years. If the increase of Prosopis glandulosa continues, a program controlling this species should also be considered.

A policy and sound program of exotic species control and removal should be instituted, especially of those listed in the study. The most important is Sorghum halpense, found commonly along the roads, in the campgrounds, and around the Chisos Remuda in the Lower Basin. Other exotic species are found locally distributed in eroded areas and around water hydrants in the campground. These can be quite easily controlled by removal. A long-range program should be adopted to rid the basin of the man-supported lawns of Cynodon dactylon. A gradual transplanting of natural grasses into the lawns from the basic list are suggested. Since the native species are clonal grasses rather than carpet-forming in nature, they will not become as dense and will be much slower to develop.

Chisos Remuda

The major corrective measure taken by the National Park Service toward this impact force should be the total removal of Chisos Remuda from the Chisos Mountains. The basin is too small and unstable in terrain, climate, and vegetation to support the constant impact of the unnatural population of horses. The effects of the horses are so widespread that the total ramification cannot even be delineated in terms of direct effects upon the vegetation. Attempts to identify them for future investigators are scattered throughout this text. The most serious effects are upon the trail system. which is unstable, poorly maintained, poorly constructed in some areas, and directly alters the vegetation. The terrain itself contributes significantly to these poor conditions. The few park visitors who benefit from the service do not justify the irreparable damage to the vegetation, increased trail maintenance costs, and the intolerable conditions which the hiker must endure because of the fecal material and dust.

In the event the program cannot be phased out, a vigorous unified program by both the National Park Service and Chisos Remuda management must be under taken to rehabilitate the impacted area around the operation. The rehabilitation program must be directed toward the halting of pollution around the corral. All present and future waste should be removed from the basin, and especially the present refuse dump near the northwest corner of the corral. A barrier system should be constructed around the corral to retrieve all the large particles, preventing their entrance into the surrounding ravine systems. The possibilities of a water filtration system to purify the runoff water from the corral should be investigated for feasibility. All baling wire and other by-products should be properly disposed of in containers for removal from the basin.

The area around the concession should undergo the general rehabilitation-revegetation program. Immediate attention should be given to the areas around the corral and to the west slope in particular. Efforts to reduce the spread of exotics and to disseminate viable seeds through feed should accompany the revegetation program.

Under the leadership of the National Park Service, a trail-respect program for the trail bosses should be initiated. The program should include interviewing the incoming trail bosses to disseminate National Park Service philosophy and information concerning the problems of trail maintenance that are related to their duties. The program could also introduce personnel to the plants, animals, history, geology, and ecology of the mountains and park. A trail-abuse fine system for off-trail walking, directed toward both the individual and concessions, should be instituted and these funds used to reconstruct abused sites. If this program is not feasible, it should be required that a seasonal ranger or naturalist accompany the larger groups during the heavy attendance periods. The National Park Service must become actively involved in preventative trail maintenance, involving those who most frequently use the trails.

National Park Concessions, Inc.

The major program of National Park Concessions should be to reduce its areal impact and transfer many of its activities out of the Chisos Basin. The complex is too large and critically located in the lower margin of the unstable evergreen woodland. The complex has greatly altered the natural drainage patterns, created extreme erosion sites, created many hard-surfaced and compacted areas, introduced numerous exotic and unnatural plant species, and made great demands on water and sewage facilities. The latter is presently creating the pollution problem at the Trailhead below the Ranger Station. Most of the facilities except for dining, food supplies, and automotive services could be more efficiently provided with less irreparable landscape damage at lower elevations in the park. Expansion of facilities and the trucking of supplies would be reduced, not to mention the aesthetic damage that the large, bare complex does by falsifying the integrity of the woodland vegetation.

If the reduction of lodging is not feasible, a vigorous program to revegetate the entire area must be initiated immediately to obscure the sprawl. To accompany the program, the woodland should be given total possession of its only natural invasion pathway into the Upper Basin. By removing the warehouse, round house, paved road, and structures along the road, the ravine could be freed of most impact. All storage of supplies and housing of support personnel can certainly be done in less critically vegetated lower elevations. This program would also reduce large quantities of road runoff water and provide a mare aesthetic and natural vegetation background for the existing complex. Every effort should be made to stabilize the abandoned area by the basic rehabilitation-revegetation program.

The areas presently impacted and those which are abandoned should be stabilized and revegetated according to the basic program. The exotic and introduced species program should also be conducted in the area.

Trails

The major program should be directed toward the phasing out of horse use on the trail system in the Chisos Basin if the long-term use of trails in planned. Because the trail system spans many miles of xerically adapted vegetation that can only slowly revegetate and stabilize the unstable slopes, the near-daily heavy use precludes little vegetation recovery to provide a natural access to the remote areas of the mountains. Few sections of the young trail system indicate stability to insure continued use in near-natural condition for years to come.

If an alteration in impact is not obtained, a long-range major program with great expenditures and consultation with ecologists, geologists, hydrologists, and engineers must be immediately instituted to insure stabilization, revegetation, and rehabilitative maintenance. A program to determine specific effects of the horse upon the trail and vegetation must be established, along with permanent plots for future comparative work. It is definitely certain that the present maintenance program is obsolete and of more detriment to the surrounding vegetation than no maintenance at all. The many days of trail-crew denuding and soil movement only promote the continued deterioration of the system which "nature" can do more naturally in several minutes during rainfall. The abandonment and rebuilding process does not provide a solution to the problem, as can be witnessed presently in the system. The few branches and fallen logs placed in the man-made gullies are not conducive to rehabilitation or revegetation.

New approaches to trail rehabilitation and maintenance should be instituted with increased crew personnel and equipment to support them. The research program must consider hard surfaces on the steep, unstable slopes of the Boot Canyon and Laguna Meadow trails and the incorporation of more drainbars. The use of drainbars to trap erosion products for maintenance purposes must be considered. This will require the use of small, powered soil conveyors since long distances must be covered and large quantities of soil and rocks must be transported in some regions of the trail system. Controlled plantings of grasses, shrubs, and trees incorporated into stone-covered slopes could reduce erosion, slippage, and shortcutting by trail riders and hikers. Immediate action must be taken to prevent horses from walking on the outer lip of the trail tread.

Since major concern has been focused on the destructive role of horses on the trail and vegetation, major consideration must be given to the cessation or reduction of horse use where it might increase use on a single trail section. Evidence indicates that the more mesic vegetation types, where stable, are less affected by trails than the more xeric vegetation types; however, more data is needed to substantiate such indications since long-range trends must be considered. A comparison of the vegetation along the lower, southern exposures on the Laguna Meadow Trail with that of its upper, northern exposures could supply pertinent data. The condition of the Window Trail and section of trail between Upper-Lower Basin, which are poor vegetationally as a result of impact, show evidence of increased or double use.

A policy directed toward reduced horse impact on Juniper Flat should be instituted. The vegetation recovery of Laguna Meadow and Stipa Flat indicates that the present condition of Juniper Flat is not natural or necessary. The flat, being close to the campground and available to less capable hikers, offers a unique habitat for an interpretative program, as does the vegetation along the short-cut trail to Laguna Meadow Trail. This trail should be restricted to hikers and have little preventative maintenance.

The complex trail system on the northern exposure of the slope between the Campfire Circle and the Ranger Station should be reduced to a single trail, as the present complex affects too great an area. The abandoned trails must undergo the basic rehabilitative-revegetation program and not receive the usual strategically positioned boulder and log.

Campground

The major rehabilitation program of the main campground and group campground areas is the control of visitors' walking while using the facilities provided. The aims should be to reduce erosion and compaction and to promote the development of a more natural vegetation. The entire campground, especially the present erosion sites and slopes, should undergo the basic rehabilitative-revegetation program. The introduction of trees and shrubs listed in the basic program is needed around the bare campsites and comfort stations to further the trend toward the potential evergreen woodland vegetation of the area.

To accompany the human control, erosion control, and revegetation programs, an attempt should be made to alleviate the habitats of the exotic and "weedy" species. The control of human walking and erosion will assist this significantly. The natural areas should be cleaned of camping debris and controlled by designated pathways wherever they must be traversed. The natural areas should also be ridded of the many Cupressus arizonica trees, and native trees, listed in the basic program, used to replace them.

Ranger Station

The major program of the Ranger Station and area should be the expansion of the facility into a Ranger Station and Mountain Woodland Interpretive Center. The center should occupy the present impacted circle and be a circular, two-storied building with Ranger offices and restrooms on the ground level and an overhanging second level consisting of a 360° observation floor, and with a centrally located, self-guided interpretive center. With the improvement or relocation of concession lodging to a lower elevation and with a vigorous revegetation program, the present impacted area would provide a picturesque view of the basin and would be an excellent educational asset to the Park. A circular parking arrangement around the base of the center would alleviate the present large parking lot, obscuring the automobiles from the viewers, and more appropriately provide for runoff in all directions. The included restroom facilities would permit the removal of the comfort station below the present Ranger Station, while the fire and rescue equipment could also be obscured from the visitors' view.

From the center, the visitor could be directed to a self-guided nature tour of the Window View circle, Juniper Flat-Laguna Meadow Trail shortcut, or the longer Window Trail.