Idaho Batholith ecoregion

The Eastern Batholith ecoregion is located in the easternmost portion of the Idaho Batholith, which is just northwest of the Continental Divide. The region is forested and mountainous. Its surface waters tend to be very low in alkalinity, which is caused by its underlain intrusive rocks of the Cretaceous Idaho Batholith. Alkalinity is the measure of a solution's capacity to neutralize or buffer acids. The average annual precipitation ranges from 16-55 inches (40.6-139.7 cm). Climax vegetation includes subalpine fir (Abies lasiocarpa), Douglas-fir (Pseudotsuga menziesii), and ponderosa pine (Pinus ponderosa). Logging, grazing, mining, and recreation illustrate some of the more common land uses of the area.[19]

The Lochsa Uplands ecoregion is mountainous and dissected. Granitic rocks underlay the region which is spread out by volcanic ash deposits that help improve the soil fertility and water retention in the uplands. Grand fir (Abies grandis) and Douglas-fir are common throughout the region. Engelmann spruce (Picea engelmannii) and subalpine fir grow at high elevations, while cedar-hemlock-pine forests are found in canyons and on north-facing slopes.[19] [20]

The Lochsa-Selway-Clearwater Canyons ecoregion features fast-flowing rivers transporting cold water. As the depths of canyons increase, they become warmer and drier. The ecoregion is dominated by Douglas-fir, grand fir, western redcedar (Thuja plicata), western larch (Larix occidentalis), and western white pine (Pinus monticola). Ponderosa pine is found on lower, drier sites. There are large tracts of wilderness here and the Selway River watershed is located within the region. Logging is common in non-wilderness areas.[20]

Sedimentary (those formed by the deposition of sediment) and extrusive (those formed by magma cooling at the Earth's surface) rocks largely underlay the Dry, Partly Wooded Mountains ecoregion.[21][22] Granitics are less likely to be found here than in any other part of the Idaho Batholith ecoregion, which is uncharacteristic. This region is on the leeward (or downwind) side of the mountains, meaning it is dry and receives very little precipitation. Unlike any other parts of the Idaho Batholith ecoregion, there is a mosaic of shrubland, open Douglas-fir forests, and aspen occurs. Mining is affecting water quality, and rapid residential and commercial growths are occurring near the city of Ketchum, Idaho.[20]

The Glaciated Bitterroot Mountains and Canyons ecoregion is spread out by volcanic ash and sediment left from glaciers. It is characteristically underlain by granite. The summits of mountains are high enough here to capture moisture from the Pacific Ocean, unlike in nearby ecoregions. Common vegetation includes grand fir, Douglas-fir, and western larch, while Engelmann spruce and subalpine fir can be found on north-facing slopes and at high elevations. Most of the region is wilderness or contains no roads, although recreation is common here.[20]

The Foothill Shrublands-Grasslands ecoregion lies in the rain shadow of the high mountains, as does the Dry, Partly Wooded Mountains ecoregion. Being in the rain shadow of the mountains means that most of the area is dry and treeless. The landscape is covered by vegetation such as shrubs and grasses. Part of the region is situated near Boise, Idaho, which is experiencing residential development in rural areas; otherwise, land is mostly used for grazing.[20]

The High Glacial Drift Valleys ecoregion contains geological features formed by glaciers such as outwash plains and moraines, which are accumulations of unconsolidated glacial debris.[23] The region also contains terraces, wetlands, and hills. Sedges (Cyperaceae) and rushes (Juncaceae) originally grew commonly in wet soils. In drier soils, bunch grasses and mountain big sagebrush (A. tridentata subsp. vaseyana) originally occurred. Lodgepole pine (Pinus contorta subsp. latifolia) and ponderosa pine originally grew in valley floors. Cold and snowy winters occur here. Large amounts of runoff from melting snow in the mountains occur during the spring. The region serves as pasture for livestock during the summer months. Land is also used for cropland and developments for recreation. Streams suffer raised sediment and nutrient (phosphorus) levels from flood irrigation and grazing.[20]

The High Idaho Batholith ecoregion has been greatly impacted by glaciation. The glaciation of the region has resulted in geologic features such as jagged peaks, tarns, and rockland. Tarns are lakes that form in cirques (depressions that form at the heads of glacial valleys).[24] Annual precipitation is greater than surrounding ecoregions at lower elevations and the mountains are often capped with snow. The soils are shallow, contain many stones, and have a cryic (cold) temperature regime. The region includes alpine areas, subalpine parkland, and open, windblown forests of mostly non-marketable trees such as subalpine fir and whitebark pine at very high elevations. Above treeline, tundra, alpine grasslands, subirrigated meadows, and wetlands are found.[19][20]

The South Clearwater Forested Mountains ecoregion experiences maritime influences at a lower rate than ecoregions to the north, but at a higher rate than ecoregions to the south. Grand fir, found at elevations between where Douglas-fir and subalpine fir grow, is the only tree species in the region that receives maritime influences. Instability of slopes and sedimentation of streams is caused by logging. Rivers are also heavily impacted by various types of gold mining.[20]

The Hot Dry Canyons ecoregion is heavily dissected by the occurring canyons. Relief (or local relief) can reach 5,000 ft (1,524 m). Relief is the difference between the highest and lowest elevations in a given area. Much like the canyons in ecoregion 16c, the canyons here become drier and warmer as depth increases. This region receives little snowfall in the winter. Widespread vegetation includes mountain sagebrush, ponderosa pine, and various grasses. Vegetation on south-facing slopes is less than on north-facing slopes to the increased impact of the Sun due to the Earth's tilt in the Northern Hemisphere. This effect also causes the sites on south-facing slopes to be drier. Douglas-fir can also be found, but is less common than in nearby ecoregions. The bottoms of canyons have been impacted by mining. Some of these canyon bottoms are used as transportation corridors.[20]

Soils derived from granitic rocks, which are characteristically poor at retaining water spread out the Southern Forested Mountains ecoregion. This region receives marginal influence from maritime events. Ponderosa pine can be found growing in canyons, while grand fir and subalpine fir grow at higher elevations. Douglas-fir in open settings is common in the region, while sagebrush and forests can be found in the south. Like much of the Idaho Batholith ecoregion, soil disturbance results in high amounts of sediment being deposited in streams.[20]