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Boise Basin Experimental Forest

[image] The Boise Basin Experimental Forest lies on the outskirts of the small town of Idaho City, Idaho. It was established in 1933 to study management of ponderosa pine (Pinus ponderosa). It consists of 3,540 ha (8,740 acres) and is divided into three units surrounding Idaho City in southern Idaho. Idaho City was a booming mining town in the 1870s and the surrounding forests supplied material to the community. Two units were heavily affected by mining activities and the majority of trees in them now are the results of post-mining regeneration. The third unit, on steeper slopes, has many undisturbed areas (containing large areas of ponderosa pine), including a Research Natural Area.


The climate is characterized by warm, dry summers and cool, wet winters. Annual precipitation averages 635 mm with the most falling from October through June. Summers can be punctuated by downpours and severe lightning. Temperatures average -4 C in the winter and 19 C in the summer.


Soils are derived from granitic rocks of the Idaho Batholith. They are generally deep and mostly Typic or Lithic Xeropsamments, Cryumbrepts, Cryoboralls, Cryorthents, and Cryocrepts with pH ranges from 5.5 to 7.0. The 50-year ponderosa pine site index ranges from 53 to 66.


Interior ponderosa pine dominates the forest cover at Boise Basin. Prior to successful fire exclusion, frequent surface fires maintained the pine with patches of quaking aspen. Douglas-fir occupies many settings, with mountain shrubs occupying the cooler aspects and shallow soils.

Long-Term Data Bases

There are long-term data bases on historical fire return intervals, soils, habitat types, and vegetation trends.

Research, Past and Present

The earliest studies, beginning in 1933, evaluated different methods of selecting mature trees for harvest and the effects of remaining tree patterns on tree growth, reproduction, and undergrowth vegetation. Crews installed permanent transects for monitoring tree reproduction and undergrowth vegetation. Subsequent studies evaluated factors affecting germination, survival, and growth of young ponderosa pine and the phenology of trees and undergrowth vegetation in ponderosa pine forests. Competition factors for planted and natural pine seedlings were investigated in 1937, followed by two studies of seed storage, viability, and germination of stand management as root sytems of trees and seedlings, porcupine feeding relationships with ponderosa pine, and thinning and pruning methods.

Later studies compared timber production under individual tree versus group selection methods of harvest, the viability of seeds stored in the soil, site preparation methods for tree planting, tree seed dispersal, application of plant hormones, and conversion of old growth stands to second growth.

Current activities include how various shade densities affect planted tree seedlings on harsh sites, the historical changes in stand composition and density, continued monitoring of the 1933 transects, and demonstration areas relating to ecosystem management and health.

Major Research Accomplishments and Effects on Management

Research at Boise Basin has provided important information on ponderosa pine management, habitat types in dry forests, ponderosa pine regeneration, and response of ponderosa pine to prescribed fire.


US Forest Service
's Region 4, Boise National Forest, National Interagency Fire Center, University Of Idaho, and Boise Cascade Corp. have collaborated with the Rocky Mountain Research Station's scientists.

Research Opportunities

There are research opportunities at Boise Basin on the following subjects: ponderosa pine restoration, the urban-rural interface, and recreation.


There are no facilities at Boise Basin, which is located about 50 km northeast of Boise, on Highway 21.

Lat. 4349' N, long. 11550' W

Contact information

Boise Basin Experimental Forest
US Forest Service

Rocky Mountain Research Station
1221 South Main
Moscow, ID 83843
Tel: (208) 882-3557

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