18 
component in SNC directly affected visual obstruction 
measurements. Duebbert et al. (1981) suggested that 
canopy cover in an established stand should be about 75 % 
grasses and 25% legumes. They also provided seeding 
guidelines that were directed toward achievement of this 
ratio of grasses to legumes. In Montana Dubbs (1975) 
found that (1) grasses were tallest when grown with a 
legume, (2) mixtures of grass and alfalfa yielded on the 
average 3.7 times more forage than grasses seeded in pure 
stands, and (3) grass mixtures usually were no more pro- 
ductive than pure stands of grass and should be planted 
only for some special purpose. Management of cover for 
wildlife should be viewed as a special-purpose effort. 
Mixed or pure stands of grasses are probably the best man- 
agement option for sites with heavy infestation of noxious 
weeds or high densities of pocket gophers. In contrast to 
stands dominated by grass, stands dominated by alfalfa 
usually showed extreme fracturing and lodging and consis- 
tently poorer visual obstruction. On the other hand, stands 
dominated by tall wheatgrass provided higher visual ob- 
struction than those dominated by intermediate wheat- 
grass or the pubescent variety of intermediate wheatgrass 
(A. i. trichophorum). Tall wheatgrass was also more 
tolerant of saline soils. Unlike smooth brome, intermediate 
and tall wheatgrass did not invade habitats adjacent to 
SNC stands. 
In addition to SNC, native plant species and shrub or 
tree seedlings were a part of the initial floristic composi- 
tion (Egler 1954). Annual ring counts of shrub and tree 
saplings from older age-class stands of SNC indicated that 
they were established in the first or second growing sea- 
sons. The presence of large shrubs and tree saplings was 
noticeably more pronounced in stands near shelterbelt 
plantings and in areas of 45 cm or more of annual precipi- 
tation, Although native plant species were present in SNC 
stands during all of the first 10 growing seasons, patterns 
of succession toward dominance by these species were evi- 
dently masked by the vigor of SNC. Therefore, the use of 
native plant species as well as shrubs or trees is mostly 
negated for predicting successional patterns and the times 
of treatment for management of SNC. 
Problem Related Species 
Undesirable and invader species were not consistent 
features of SNC stands but were present in some individual 
stands. Older stands with few species present other than 
the SNC mixture were generally stands with a history of 
intensive chemical and tillage management, of proper es- 
tablishment procedure, and of few fossorial rodents. These 
stands were the result of good farming practices by mana- 
gers and cooperative farmers and were a definite asset to 
the SNC resource units. 
Nearly all stands had at least one species present that 
could be classified either as a noxious weed, a problem 
farm weed, or a nuisance weed. Problem-related plant 

species were usually local in nature and not concomitant 
with the objectives of SNC management. The worst con- 
centrations of problem weeds in the SNC stands were seen 
on or around former farmyard, corral, and barn sites, on 
winter livestock feeding sites, or on sites with excessive 
manure accumulations. A regional guide for multiple or 
single species control is not presently available. In some 
instances use of herbicides to suppress weeds adversely 
affects the SNC mixture by removing alfalfa and sweet 
clover. In other instances alfalfa attracts pocket gophers 
and indirectly aids weed infestation of SNC through weed 
establishment on mounds, For areas with a concentrated 
broad-leaved weed problem, replacement of the SNC mix- 
ture with a mixture of grass species only would permit in- 
tensive use of herbicides and would also be less attractive 
to pocket gophers. 
Many of the more obvious weed species are temporarily 
subdued in SNC stands by annually mowing, flailing, 
burning, or swathing. Considerable amounts of public 
monies and manpower, much of which may result from 
unjustifiable complaints made by individuals or by local 
weed commissioners, are being used on these weed prob- 
lems. Several weed species, which are not regulated 
noxious weeds, also provide benefits to wildlife. Leafy 
spurge, wormwood, Canada thistle, musk thistle, and 
plumeless thistle necessitate special management on public 
lands. The weed problem on public land or, more spe- 
cifically, the threat of a small reservoir of problem weeds 
on public lands to adjoining private lands, many of which 
already receive intensive weed tillage and herbicide treat- 
ments annually, needs to be addressed to a greater extent 
in the near future. 
Stand Longevity 
The useful life expectancy of SNC was not determined 
in this study, but a few stands have retained their SNC 
species composition after 10 years of nontreatment. The 
quantities of wildlife production and attractiveness to 
SNC stands 8 years old or less have been well documented 
(Duebbert 1969; Duebbert and Kantrud 1974; Duebbert 
and Lokemoen 1976, 1977, 1980), but the same quantities 
for older stands of SNC are unknown. However, substan- 
tial waterfowl nest densities and production have been 
found in older stands dominated by smooth brome and 
with a haying history. These stands ranged in age between 
15 years (Vorhees and Cassel 1980) and 20 years (A. T. 
Klett, unpublished data). It seems probable, then, that 
SNC on good sites could also produce substantial quanti- 
ties of wildlife for 15 years or longer. 
During the time of initial evaluations of SNC (late 
1960’s-early 1970's), the concern of an energy crisis of 
fossil fuels had not yet been advanced to the alarm and 
conservation stage of the present. Likewise, stand quality 
or longevity was a minor concern to land managers and 
administrators because many of the extensive wildlife 
