Woodland management and productivity

FRANCIS T. HOLT, state woodland conservationist, Soil Conservation Service, helped prepare this section.

This survey area has about 190,000 acres of woodland. About 125,000 acres of this is commercial woodland, and the rest is noncommercial woodland (25). This section pro vides information that can aid landowners in managing this resource.

The main forest type in the county consists of redwood and Douglas-fir (9). Madrone, red alder, and California laurel grew in some areas, and there are places where the dominant forest type is Pacific ponderosa pine and Douglas-fir.

The county is a transitional zone from true timber types to lesser woody vegetation, and a few old-growth remnants of redwood can be found throughout the county. These are representative of some of the most southern extensions of these trees(16).

The importance of the woodland resource in Santa Cruz County has changed in recent years. Although several thousand acres are still used for commercial production of timber, the rapid increase in population in the county has resulted in increased homesite development on soils that were formerly used exclusively for timber production. In formation in this survey concerning potential for timber production can be used to plan management of these soils for either purpose.

If the soils are used exclusively for commercial timber production, various cultural operations may be needed to maintain healthy and esthetically pleasing stands of trees. Thinning some stands may be necessary in some areas, and trees may need to be planted in others. Other stands of trees may be near maturity and ready for harvesting. During all operations in the timbered areas, erosion control practices should be used. Suitable practices include: 1) yarding uphill with high-lead equipment; 2) yarding on the contour with skidding equipment; 3) logging with light equipment where possible; 4) exposing as little mineral soil as possible; and 5) never stripping steep areas. Roads must be located on a grade of 12 percent or less and well above streams and bottoms of drainageways. Effective surface drainage must be pro vided for roads and landings. Cuts and fills should be seeded and mulched. Adequate provisions must be made to safeguard the trees from harmful insects and from fire.

It is essential that all operations in timbered areas comply with state and local regulations. Professional ad vice should be sought about this aspect of woodland management.

Table 3 contains information useful to woodland owners or forest managers in planning the use of the soils for wood crops. Only those soils suitable for wood crops are listed, and the ordination (woodland suitability) symbol for each soil is given. Only soils bearing the same ordination symbol require the same general kinds of woodland management and have about the same potential productivity (11).

The first part of the ordination symbol, a number, indicates the potential productivity of the soils for important trees. The number 1 indicates very high productivity; 2, high; 3, moderately high; 4, moderate; and 5, low. The second part of the symbol, a letter, indicates the major kind of soil limitation. The letter x indicates stoniness or rockiness; w, excessive water in or on the soil; t, toxic substances in the soil; d, restricted root depth; c, clay in the upper part of the soil; s, sandy texture; f, high content of coarse fragments in the soil profile; and r, steep slopes. The letter o indicates insignificant limitations or restrictions. If a soil has more than one limitation, priority in placing the soil into a limitation class is in the following order: x, w, t, d, c, s, f, and r.

In table 3 the soils are also rated for a number of factors to be considered in management. Slight, moderate, and severe are used to indicate the degree of major soil limitations.

Ratings of equipment limitation reflect the characteristics and conditions of the soil that restrict use of the equipment generally needed in woodland management or harvesting. A rating of slight indicates that use of equipment is not limited to a particular kind of equipment or time of year; moderate indicates a short seasonal limitation or a need for some modification in management or equipment; severe indicates a seasonal limitation, a need for special equipment or management, or a hazard in the use of equipment.

Seedling mortality ratings indicate the degree that the soil affects expected mortality of planted tree seedlings. Plant competition is not considered in the ratings. Seedlings from good planting stock that are properly planted during a period of sufficient rainfall are rated. A rating of slight indicates that the expected mortality of the planted seedlings is less than 25 percent; moderate, 25 to 50 percent; and severe, more than 50 percent.

Considered in the ratings of windthrow hazard are characteristics of the soil that affect the development of tree roots and the ability of the soil to hold trees firmly. A rating of slight indicates that trees in wooded areas are not expected to be blown down by commonly occurring winds; moderate, that some trees are blown down during periods of excessive soil wetness and strong winds; and severe, that many trees are blown down during periods of excessive soil wetness and moderate or strong winds.

Ratings of plant competition indicate the degree to which undesirable plants are expected to invade or grow if openings are made in the tree canopy. The invading plants compete with native plants or planted seedlings by impeding or preventing their growth. A rating of slight indicates little or no competition from other plants; moderate indicates that plant competition is expected to hinder the development of a fully stocked stand of desirable trees; severe means that plant competition is expected to prevent the establishment of a desirable stand unless the site is intensively prepared, weeded, or otherwise managed for the control of undesirable plants.

The potential productivity of merchantable or important trees on a soil is expressed as a site index. This index is the average height, in feet, that dominant and co-dominant trees of a given species attain in a specified number of years. The site index applies to fully stocked, even-aged, unmanaged stands. Important trees are those that woodland managers generally favor in intermediate or improvement cuttings. They are selected on the basis of growth rate, quality, value, and marketability.

Trees to plant are those that are suitable for commercial wood production and that are suited to the soils.