Native Vegetation of Idaho E.W

202 Rangelands 8(5), October 1986 munities of the salt desert ranges could be evolved. Such a faulty or haphazardlyapplied as answersto complex prob- knowledge was the visionof Dr. Lee Sharp. His quest may lems. Rangemanagement appeared at times to be gripped in have been decadesahead of itstime, butto seek such know- a paralysis induced by the shrill complaints directed at any ledgeis atributeto uncommonknowledge of rangeland resour- managementplan. ces. Resourcemanagers may have been forced into positions RangeImprovement by seeding exotic wheatgrasseslarge- of inertia as range science searchedfor new direction, but ly ended by the mid 1960's because of concern by some during the last two decades the rangelands of the Snake environmentalists about the conversion of degraded sage- River Plains have remained dynamic. Much of thechange in brush communities to wheatgrass stands. The emerging sagebrush ranges has literally been fueled by cheatgrass. field of wildlife management lashed out at range improve- Reoccuring wildfiresand resulting annual grass dominance ment as aconvenient cause for thedecline in population size refused to stand still whilesociety established a policy for of various game species on rangelands. Present day knowl resource management. edge of the population dynamics of some of these species Perhapswe need to ride upto theShoshone Basin and sit suggestscauses for changes in numbers are far more com- in the saddle on the high ridges where J.E. Bower looked plex than can be explained by localized range improvement. down and saw thepristine sagebrush/bunchgrasscommuni- The sagebrush/bunchgrassrangelands of the Snake River tiesof the SnakeRiver Country. Such a view may help crys- Country went from nobody's land in the 1930's to every- talize a policywhere the perpetuation ofthe basic assemb- body's land in the 1970's. Rangeland managerswere often lage of soils and plant communities in equilibrium with the bombarded by a hostof conflicting demands concerning the potential of theenvironment is the overriding principleupon uses and manipulation of rangelands. In frustration, some whichresource managementmust be built. turned to simplistic grazing systems that were inherently Native Vegetation of Idaho E.W. Tisdale Knowledge of the vegetation of the State is still incom- plete, although much progress has been made during the POTEP(T1AL VEGETATION pastthree decades. We now havefairly adequate data for the OFIWHO forest, sagebrush-grass, and grassland communities, but information for others, including the salt-desert shrub, LEGEMD mountain and is still P)C NThWEST GRAS9N1 brush, alpine riparian types, sketchy. GRCGRASS LGAASS Classification of the state's vegetation in recent years has ESCS- NOcflS€4= PT been done mainly in categories and nomenclature used in SGERRJSM GRASS the International BiologicProgram. In this system theforma- ST—SEflT GRRIJS WOLAND tion denotes the broadest class, such as forest or grassland, I/lAS _MSPCR and regionis used to describe a of communities with SAS'TI MR group FONEST similar appearance and regional climate such as conifer = COMFESOUS forest or Seriesare ofcommunities sagebrush-grass. groups OFI€R FEATLPES characterized by a single dominant species, and habitat LAS FR10 types are smaller units with relatively uniform biotic and — .aasao abiotic composition and structure. Series, which represent easily recognized and fairly extensive communities, were chosen as the most appropriate level for description in this article. The Physical EnvIronment Idaho is a large state (53 millionacres), extending about 500 miles from its northern toits southern border. Four major physlographic regions, i.e.: Northern Rocky Mountain, Mid- dle Rocky Mountain, Columbia Intermontane,and Basinand Range are represented.Seventy-five percent of the state is mountainous, and the only large areas of level terrain occur —..—..—..—...t onthe SnakeRiver Plainsin the southern part. A great variety FIg.1. Mapof main vegetationtypes and other landscapefeatures of of surface rock materials occur, including argillites, quart- are due zites Idaho.Boundaries approximate totheir actual irregularity and metasedimentsin the northern part; granitic mate- and the scale ofthe figure. rials in the central and Columbia basalt and other Batholith; of bess and ash add volcanics cover much of the western and southern portion. deposits volcanic surface material over Alluvialsediments also occur on the SnakeRiver Plains,and much of the northern and western portions. Climate varies greatly, mainly in response to physiogra- Theauthor IsProfessor Emeritus, Department of Range Resources, Univer- phic influences and latitude. The northern part has annual sityof Idaho. Rangelands 8(5), October 1986 203 precipitation ranging from 30 to 60 inches in the forested million acres. The forests are mainly coniferous, although areas to 13 to 22 inches in the canyons of the Snake and deciduous trees occur in riparian sites and aspen (Populus Salmon Rivers. Southern Idaho is generally much drier, and tremuloides) dominatescertain areasin southeasternIdaho. large areasof the Snake River plains receive 10to 12 inches The coniferous forest series occur along a gradient of or less. Half or more ofthe annualprecipitation occursin the moisture and temperature which covers a wide climatic wintermonths in most ofthe State, and the mid-summersare range. The most mesic series is that dominated by western extremely dry. Temperaturesvary greatly with elevation, but hemlock (Tsuga heterophylla), the mostshade tolerantand are generally milder than those in comparable areaseast of moisture-demandingof the conifers. Slightlyless moistsites the Rockies. are occupied by the western redcedar (Thu/ua plicata)ser- A great variety of soils hasdeveloped in responseto parent ies, with a wider range of temperature and moisture toler- material and climatic influences. Many soils are rockyand/or ance. The moist and relatively mild climate of both series is shallow, butmost are relativelyproductive withinthe limits of available moisture. Some, such as the granitic soils of the Idaho batholith are highly erosive when the natural plant cover is disturbed. FIg. 3. Large pondorosa pine growingas successional species in Douglas-fir type. Tree reproduction is mainly ofDouglas-fir. indicated by thelush growth oftrees, and by thenature of the Fig. 2. Western redcedar type with some western hemlock and understory which contains many disjunct species, common western larch included. in West Coastal forests, but not found inland except in this Vegetation Types northern Idaho area. The understory is rich in ferns, shrubs and forbs fern oak In broadest the including lady (Athyriumfilix-femina), terms, vegetation ofthe state may be visu- fern (Gymnocarpum dryopteris), menziesia for- alized as of conifer forests in the northern (Menziesia consisting mainly ruginia), queen's cup (Clintoniauniflora), and gold-thread and central parts, with shrub vegetation in the southern por- and a band of in the west (Coptisoccidentalis) tion, grassland central part. Other Another series with high moisture confined types include woodland, and requirements juniper riparian alpine vegeta- to nothern Idaho is formed by mountain hemlock (Tsuga tion (Fig. I). mertensiana) which occurs in scattered stands at higher elevations. Common include Forest Vegetation understory species beargrass (Xerophyl!um tenax) and wood rush (Luzula hitchcockii). Forest is oneof the major formations, occupying about 20 Some conifer series have awider distribution in the State. 204 Rangelands 8(5), October 1986 The grandfir (Abies grandis) series, for example, occurs in species tend to maintain themselvesfor long periods due to all but the southeastern section. It occupies sites with some the longevity of the individuals. ofthe mild climatic characteristics of the hemlock and western redcedar types, but with less available moisture. Shrub Vegetation High elevationsthroughout the State are occupied by the This formation occupies virtually all of the Snake River subalpine fir (Abies lasiocarpa). Its habitat is marked by low plain and adjacent foothills, and some of the communities temperatures and a very short growing season.The under- extend much farther North. Thetotal areaof potential shrub story is well developed and contains species such as huc- vegetation is about the same as the forested lands, but the kleberries (Vaccinium spp.) and bluejoint (Calamagrostis shrub typeshave been morealtered by land use.The forma- canadensis). The upper part of this type, just below timber- tion includes the extensive sagebrush-grass region, along line, often contains open heath and grassy balds. with a number of smaller types. Douglas-fir(Pseudotsuga menziesii) forms awide-ranging series which occursin all forested parts ofthe State. It occupies sites whichare drierthan those supporting grand fir and warmerthan those occupied by subalpine fir. Thetree stands are generally more open than in the series described so far and support well-developed understories dominated by shrubssuch as ninebark (Physocarpus malvaceus) or grasses suchas Idaho fescue (Festuca idahoens/s). Lodgepole pine (Pinus contorta) occursextensively as a fire successional species but also forms a climax series in certain habitats. These generally have shallow, excessively drained soils, occurring in areas cooler than those of the Douglas-fir type and drier than those ofthe grand fir series. Lodgepole pine is well adapted to cold-air drainages. Com- mon understory species

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