Effect of fire on perennial grasses in central semiarid Argentina
Issue Date
2001-09-01Keywords
piptochaetium napostaenseStipa tenuis
Stipa gynerioides
basal area
semiarid grasslands
mortality
fires
fire effects
prescribed burning
environmental factorsPoaceaesoil water contentseasonal variationArgentinaStipafire mortalityfire intensitythermal death pointPiptochaetium napostaense (Speg.) Hack.Stipa tenuis Phil.Stipa gynerioides Phil.
Metadata
Show full item recordCitation
Pelaez, D. V., Boo, R. M., Mayor, M. D., & Elia, O. R. (2001). Effect of fire on perennial grasses in central semiarid Argentina. Journal of Range Management, 54(5), 617-621.Publisher
Society for Range ManagementJournal
Journal of Range ManagementAdditional Links
https://rangelands.org/Abstract
Fire is a key factor in the temperate semiarid region of central Argentina. The objectives of this work were to evaluate the effect of different fire intensities applied during different seasons under field conditions on the mortality of Piptochaetium napostaense (Speg.) Hack., Stipa tenuis Phil., and Stipa gynerioides Phil., 3 of the dominant grasses within the region and to determine their thermal death points in the laboratory. Ten plants of each species were exposed to low fire intensity (300-400 degrees C), high fire intensity (500-600 degrees C), and no fire (control) in April and December 1994, May 1995, and January 1996. Fire treatments were applied with a portable propane plant burner. The thermal death point was determined (during fall and spring) using the Wright's technique. Although mortality with high fire intensity was always higher than mortality with low fire intensity for all species, differences were not significant (p > 0.05). Pooling both treatments, the highest (p < 0.05) average mortality for P. napostaense (55%) and S. tenuis (85%) was observed after the May burn. Average mortality for S. gynerioides was similar (p > 0.05) for all burning dates. Only after the May burn, was average mortality of P. napostaense and S. tenuis higher (p < 0.05) than average mortality of S. gynerioides. The thermal death point was similar in all studied species. It was 65 degrees C during the fall, and 68 degrees C during the summer. This could explain, at least in part, similar mortalities (except after the May burn) between species and the date of burning found in this study.Type
textArticle
Language
enISSN
0022-409XScopus Count
Related items
Showing items related by title, author, creator and subject.
-
Bud viability in perennial grasses: water stress and defoliation effectsEffects of the timing and frequency of defoliation under different levels of soil water availability were evaluated on bud metabolic activity and subsequent outgrowth in the desirable (i.e., palatable) Stipa clarazii Ball. and S. tenuis Phil. in competition with the undesirable (i.e., unpalatable) S. gynerioides Phil. Field studies on these native, perennial tussock grasses were conducted from 1995 to 1997 in temperate, semiarid Argentina. Our working hypotheses were 1) axillary bud activation and subsequent tillering are lower under water stress than under higher soil moisture conditions in S. clarazii, S. tenuis, and S. gynerioides, 2) when compared to undefoliated controls, activation, and subsequent outgrowth of axillary buds reach similar or greater values in S. clarazii and S. tenuis after early (vegetative stage of development), but not late (during internode elongation) defoliations or increased defoliation frequency (vegetative+ during internode elongation) during each growing cycle. Additionally, it was expected that the greatest reduction of axillary bud metabolic activity and outgrowth would ocurr on plants defoliated twice, and 3) axillary bud activation and succeeding tillering are greater in the undefoliated S. gynerioides when the desirable species are defoliated than when they remain undefoliated. With a few exceptions, our results led us to reject all 3 hypotheses. Responses of axillary buds were in general specific to the species and treatments, to sampling time, and to the cumulative effects of previous treatments. This makes predictions of plant responses of these species under natural field conditions difficult, where they are often defoliated under water stress.
-
Cattle prefer endophyte-free robust needlegrassRobust needlegrass (Achnatherum robustum [Vasey] Barkw. = Stipa robusta [Vasey] Scribn.) is a high-biomass rangeland species that is adapted to warmer temperatures and matures later than most cool-season grasses. However, it has been associated with negative animal effects including avoidance. We compared populations of Neotyphodium and P-endophyte-infected endophyte-infected (E+) and endophyte-free (E-) robust needle-grass for animal preference. Leaf blades were fed to yearling heifers in 3 trials of 8-min cafeteria sessions for 4 to 5 days each. Trial 1 (27-30 May) compared E+, E-, basin wildrye (Leymus cinereus [Scribn. Merr.] A. Löve), and tall wheatgrass (Thinopyrum ponticum [Podp.] Barkw. D.R. Dewey). Basin wildrye consumption (425 g) did not differ from tall wheatgrass (342 g), but basin wildrye consumption exceeded E- (258 g), which in turn exceeded E+ (117 g) (16 animal-sessions). Basin wildrye was dropped from Trial 2 because its consumption exceeded that of both E- and E+. In Trial 2 (1-5 June), consumption of E-, E+, and tall wheatgrass did not differ. Tall wheatgrass was dropped from Trial 3 to allow direct comparison of E- and E+. In Trial 3 (13-17 July), consumption of E- (585 g) exceeded E+ (145 g) (15 animal-sessions). In Trial 3, animals often rejected E+ forage before tasting. Discrimination against E+ was greater at the end of Trial 3 than at the beginning. The reputation of robust needlegrass for animal avoidance may be more related to its endophyte infection status than to the grass itself. Differences in forage-quality parameters were not large enough to account for the observed differences in preference. Ergot and loline alkaloids were not found in either E- or E+, therefore they cannot be responsible for the observed avoidance of E+. Non-trace amounts of ergot alkaloids were found only in seed collected in the Sacramento Mountains of New Mexico and not at other locations in New Mexico, Arizona, or Colorado.
-
Impact of clipping on root systems of 3 grasses species in TunisiaThe study concerns the impact of herbivory on the root systems of 3 perennial grasses, buffelgrass (Cenchrus ciliaris), digitgrass (Digitaria commutata) and needlegrass (Stipa lagascae), growing in the arid zones of Tunisia. The study simulated animals feeding of the grasses by affecting cuttings at various times throughout the spring growing period. The following effects on the root systems of the grasses were observed. When there is continual overgazing (simulated by cutting all sprouts down the ground level along the spring), more than 65% of the roots off all 3 species are found in the salty upper 15 cm of soil. In case of medium average grazing (simulated by 2 to 3 cuttings), the root system again remains superficial for buffelgrass (C. ciliaris), with 58 to 67% of the roots located in the upper 15 cm of soil. Digitgrass (Digitaria commutata) and needlegrass (Stipa lagascae), however, develop deeper roots with 68 to 86% in the upper 30 cm of soil. When grazing is light (just one cutting), all 3 species perform all most exactly as if there had been no grazing compared to (a control plot) with 85% of the root system located in the upper 50 cm and about 15% at 50 to 75 cm of ground depth. On the basis of this experiments, it is suggested that grazing on these grasses should be allowed just once each spring, thereby allowing: 1- To take advantage of the aboveground contained in these grasses in spring. 2- Preservation of a deep root system which will thereby have a much better chance of getting through the water stress summer season.
