Restoring Landforms and Soils

 
Excavator reworks the grade of a steep hill
Restoration of natural landforms required the use of heavy equipment.

NPS photo

Soil properties were restored to approximate those of surrounding, undisturbed soils. The most severely altered soil properties were compaction, alteration of aggregate structures, and loss of organic matter. To decompact soils and convert platy and blocky aggregate structures to natural crumb or granular structures, moist soils were cultivated to a depth of 5 to 8 inches with small, agricultural-type equipment . Cultivation was conducted outside the drip lines of mature trees and was halted or made shallower if major roots were encountered. To restore organic matter in the topsoil, highly decomposed forest bark humus was added during cultivation in some locations. Contractors conducted soil tests to determine application depth of humus necessary to raise organic matter content to 7 to 10 percent by weight. Because a major influx of carbon in organic matter can cause soil microorganisms to proliferate and sequester the soil’s limited nitrogen for their own use, nitrogen fertilizer was added during cultivation if soil tests indicated that this was necessary.

 
Line of granite rocks form a small dam across a gulley to check the flow of water.
Rock check dams slow the flow of water and reduce its ability to erode the soil.

NPS photo - Athena Demetry

Loosened soils were protected with wood chip mulch, soil retention blanket, or native litter and duff, which was salvaged prior to demolition if present or was collected from surrounding areas for restoration of linear features such as roads and trails.

During human occupancy of Giant Forest, erosion gullies had developed where roads, trails, and parking lots concentrated runoff from rain storms or snow melt. In most sites, the removal of the hardened asphalt surface and restoration of the landform was sufficient to correct the erosion problem. In sites where the erosion gully would continue to receive concentrated drainage, rock check dams were installed to slow the flow of water and reduce its ability to erode the soil.

All landform and soil restoration work listed was accomplished by contractors.

Last updated: October 3, 2023

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47050 Generals Highway
Three Rivers, CA 93271

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559 565-3341

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