Browsing Journal of Range Management, Volume 54, Number 6 (November 2001) by Subjects
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Adaptation of perennial triticeae to the eastern Central Great PlainsThe tribe Triticeae contains over 250 perennial species that are components of grasslands in the temperate and sub-arctic regions of the world and includes some of the world's most valuable forage and rangeland species. Many of these species had not been evaluated previously in the Central Great Plains, USA. A subset of the germplasm of the tribe Triticeae which included over 100 accessions of 55 different species was evaluated in a replicated, space-planted trial in eastern Nebraska during 1994-1996 to determine the survival and forage productivity of the accessions. The evaluated accessions were representative of perennial Triticeae genera and genomes. Perennial grasses of the Triticeae are based on the P, St, H, Ns, E, W, Y genomes and an unknown Xm genome(s). Triticeae that survived and had acceptable forage yields during the period of the trial were the Agropyron's-crested wheatgrasses (PP and PPPP genomes), Psathyrostachys-Russian wildryes (NsNs genomes), Thinopyron's-intermediate and tall wheatgrasses (EEEEStSt and EEEEEEStSt genomes), some Elymus (StStHH genomes), several Leymus (NsNsXmXm genomes), and Pascopyrum-western wheatgrass (StStHHNsNsXmXm genomes). Several Leymus species had not been evaluated previously in this region but showed considerable potential and merit additional evaluation, including L. chinensis, L. akmolinensi, L. racemosus, L. sabulosus, and L. secalinus. Species with only the H genome (Hordeum) and St genome (Pseudoroegneria) were not adapted to the region because of poor survival or low productivity. The study provides an example of how the rapidly emerging field of genomics can have practical applications to grasslands and rangelands.
Long-term plant community development as influenced by revegetation techniquesA revegetation techniques study was initiated during the fall of 1976 in northwestern Colorado in a disturbed sagebrush (Artemisia tridentata Nutt.) community. The study included 2 irrigation treatments, three seed mixtures, 2 seeding techniques, and 2 fertilization treatments. Short-term results were published and conclusions were made regarding the initial success of each treatment. The objective of the current study was to determine the effects of each treatment on plant community production, species composition, and species diversity after 20 years of plant community development. Among irrigated plots, the native seed mixture produced greater aboveground biomass compared to an introduced mixture and a mixture of both native and introduced species (combination seed mixture). The native seed mixture also resulted in greater total species richness than the introduced mixture when averaging over all other treatments. Altered seeding rate ratios among life forms as well as altered seeding methods (drill versus broadcast seeding) did not significantly alter plant community development after 20 years. However, a single application of nitrogen and phosphorus significantly increased grass production on plots seeded to the combination seed mixture. All revegetation plots have remained grass-dominated. However, shrub biomass was greater in the native and combination mixtures than in the introduced mixture under initial irrigated conditions in part due to successful establishment and growth of four-wing saltbush (Atriplex canescens Pursh Nutt.). Thus, the seed mixtures evaluated in this study have resulted in distinctly different plant communities and demonstrate that such initial treatments can influence long-term plant community development on severely disturbed rangelands. Broadcast seeding a native seed mixture that has been irrigated for 2 growing seasons without fertilization appears to be an effective long-term combination of cultural revegetation practices.
Suppression of annual bromes impacts rangeland: Animal responsesPresence of annual bromes (Bromus spp.), introduced annual weedy grasses, can alter seasonal patterns of forage production and quality and require management changes for efficient use of infested rangelands. We determined biological impacts of the presence of brome by comparing livestock performance on brome infested rangeland to similar sites on which brome had been suppressed by autumn application of atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)- 1,3,5-triazine-2,4-diamine] at 0.56 kg ha(-1) in 1992 and 1993. Each treatment was randomly assigned to three, 12-ha pastures. Vegetation was measured for 5 months (May to September) each year from 1993 to 1995. Each pasture was stocked with 8 crossbred steers of British breed origin (Bos taurus) from mid-May to mid-September 1993 and 1995 and to mid-August 1994. Initial body weights averaged 329 kg SD = 31 in 1993, 273 kg SD = 14 in 1994, and 272 kg SD = 21 in 1995. Brome suppression and environment influenced plant species in diets, diet quality, and livestock performance. Brome suppression reduced percentage of annual grasses in diets from 14% to 10%. Annual grasses were replaced in the diet by a variety of forb and grass species [western wheatgrass [Pascopyrum smithii Rydb. (Love)], and blue grama [Bouteloua gracilis [H.B.K.] Lag. ex Griffiths]], with specific replacement depending on year and month. Steer gains were increased from 0.92 to 1.04 +/- 0.02 kg head(-1) day(-1) (P < 0.02) and from 69 to 81 +/- 2.8 kg ha(-1) (P < 0.05) with brome suppression. This experiment demonstrated that improvement in livestock performance can be expected with the suppression of annual bromes on semiarid rangelands.
Suppression of annual bromes impacts rangeland: Vegetation responsesPresence of invading annual bromes (Bromus spp.) can alter seasonal patterns of forage production and quality and require management changes for efficient use of infested rangelands in the Northern Great Plains. We studied biological impacts of the presence of brome by comparing brome infested rangeland to similar sites in which brome had been suppressed with autumn applications of atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)- 1,3,5-triazine-2,4-diamine] at 0.56 kg ha(-1) in 1992 and 1993. Each treatment was randomly assigned to three, 12-ha pastures. Vegetation was measured for 5 months (May to September) each year from 1993 to 1995. Each pasture was stocked with 8 cross-bred steers (Bos taurus) from mid-May to mid-September 1993 and 1995 and to mid-August 1994. The forage base varied temporally by date and year, but generally was not less than 800 kg ha(-1). Brome suppression increased (P less than or equal to 0.05) crude protein concentration for western wheatgrass (Pascopyrum smithii Rydb. [Love]) in July (7.1 vs. 9.1%) and August (6.0 vs. 7.1%). With the variation in annual brome stands among years, as influenced by growing conditions, this experiment demonstrated that improvement in forage nutritional quality can be expected from suppression of annual bromes on semiarid rangelands.