In this section, we first provide a general overview of INEEL vegetation. This is followed by a brief fire history of the INEEL and discussion of the role that fire has played in shaping the current vegetation. Next, we review the history of vegetation studies at the INEEL. Finally, we discuss development of the current INEEL vegetation map and describe the major vegetation types identified on the map.

INEEL Vegetation, An Overview

The natural vegetation at the INEEL typically consists of a shrub overstory with an understory of perennial grasses and forbs. The most common shrub is Wyoming big sagebrush (Artemisia tridentata subspecies wyomingensis¹ ). Basin big sagebrush (Artemisia tridentata subspecies tridentata) may be dominant or co-dominant with Wyoming big sagebrush on sites having deep soils or accumulations of sand on the surface (Shumar and Anderson 1986). Communities dominated by big sagebrush occupy most of the central portions of the INEEL. Green Rabbitbrush (Chrysothamnus viscidiflorus) is the next most abundant shrub in many of these communities. Other common shrubs include gray rabbitbrush (Chrysothamnus nauseosus), winterfat Krascheninnikovia lanata), spiny hopsage (Grayia spinosa), prickly phlox (Leptodactylon pungens), broom snakeweed (Gutier-rezia sarothrae), and horse-brush (Tetradymia canescens). On the lakebed sediments of former Lake Terreton, assemblages occur that are very much akin to the “salt-desert shrub” communities so common in Utah and Nevada. These communities are dominated by shadscale (Atriplex confertifolia), Nuttall saltbush (Atriplex falcata), or winterfat.

Utah juniper (Juniperus osteosperma), threetip sagebrush (Artemisia tripartita), and/or black sagebrush (Artemisia nova) often dominate communities on the periphery of the INEEL on slopes of the buttes, alluvial fans, and the foothills of adjacent mountains.

The most common native grasses include thick-spiked wheatgrass (Elymus lanceolatus), bottlebrush squirreltail (Elymus elymoides), Indian ricegrass (Oryzopsis hymenoides), needle-and-thread grass (Stipa comata), and Nevada bluegrass (Poa secunda). Patches of creeping wildrye (Leymus triticoides) and western wheatgrass (Pascopyrum smithii) are locally abundant.  Bluebunch wheatgrass (Pseudoroegneria spicata) is rare at the lowest elevations but is common at slightly higher elevations to the southwest and along the eastern side of the INEEL; it is often the dominant grass on alluvial fans and slopes of the buttes and foothills.

Unlike much sagebrush steppe, which has a long history of grazing, the INEEL supports a high diversity of forbs (Vegetation Map). Common native forbs include tapertip hawksbeard (Crepis acuminata), Hood’s phlox (Phlox hoodii), Hoary false yarrow (Chaenactis douglasii), paintbrushes (e.g., Castilleja angustifolia), globe-mallow (Sphaeralcea munroana), buckwheats (e.g., Eriogonum mancum), evening primrose (Oenothera caespitosa), lupines (e.g., Lupinus argenteus), bastard toadflax (Comandra umbellata), milkvetches (Astragalus spp.), and mustards (e.g., Thelepodium laciniatum, Stanleya viridiflora, Arabis, spp.).