Disturbances on a shrubby steppe of the Monte phytogeographical province: changes in vegetation
Keywords:
fire, mechanical removal, grazing, interactions, biological crustAbstract
We evaluated the effects of individual and joint effects of fire, mechanical removal of shrubs and grazing on natural vegetation of the eastern Monte Phytogeographical Province in Rio Negro, Argentina. Four enclosures were constructed in sites where large disturbances (fire, mechanical removal and both) had taken place. Measurements were made both inside and outside them in order to evaluate not only the grazing effects in each site, but also possible interactions between the latter and large disturbances, which have not usually been reported. Several structural characteristics (shrub density and cover, aerial biomass and basal cover of herbaceous layer, and of biological crust), plus a functional one (phenology of five grasses and two shrubs) were studied. Both the fire and the mechanical removal reduced the density and area covered by the shrubby layer, and also the biological crust cover, with the effects being larger at the site were both had taken place. Bare soil was higher in the disturbed sites respect to the control due to the disappearance of the biological crust. Fire produced a qualitative change in the floristic composition of the herbaceous layer through altering the dominance from Stipa tenuis Phil. to a more palatable species as it is Stipa papposa Nees. Grazing reduced homogeneously aboveground biomass of the herbaceous layer, but extended the vegetative period of grasses and increased the size of that budget though reducing the reproductive one. The last two effects will be beneficial for secondary production since they increase the energy flux to herbivory. Large disturbances, however, could have negative effects through the reduction of the biological crust, which plays an important role in seed germination, seedlings establishment and water balance, thus contributing to ecosystems sustainability.
References
BECKER, GF; CA BUSSO; T MONTANI; MA BURGOS; AC FLEMMER & MB TORIBIO. 1997b. Effects of defoliating Stipa tenuis and Piptochaetium napostaense at different phonological stages: root growth. J.Arid Environ., 36:639-653.
BECKER, GF; CA BUSSO; T MONTANI; AL ORCHANSKY; RE BREVEDAN; MA BURGOS ET AL. 1997c. Effects of defoliating Stipa tenuis and Piptochaetium napostaense at different phonological stages: tiller demography and growth. J. Arid Environ., 35:251-268.
BELNAP, J; R ROSENTRETER; S LEONARD; JH KALTNECKER; J WILLIAMS & D ELDRIDGE. 2001. Biological soil crusts: ecology and management. Tech. Ref. 1730-
2, US Department of Interior Bureau of Land Management. Denver, Co.
BERLOW, EL; CM D’ANTONIO & H SWARTZ. 2003. Response of herbs to shrub removal across natural and experimental variation in soil moisture. Ecol. Appl., 13:1375–1387.
BISIGATO, AJ & MB BERTILLER.1997. Grazing effects on patchy dryland vegetation in northern Patagonia. J. Arid Environ., 36:639-653.
BONHAM, CD. 1989. Measurements for terrestrial vegetation. John Wiley & Sons (eds). New York, USA. 338 pp.
BOÓ, RM; DV PELÁEZ; SC BUNTING; OR ELÍA & MD MAYOR. 1996. Effect of fire on grasses in central semi-arid Argentina. J. Arid Environ., 32:259-269.
BOÓ, RM; DV PELÁEZ; SC BUNTING; OR ELÍA & MD MAYOR. 1997. Effect of fire on woody species in central semi-arid Argentina. J. Arid Environ., 35:87-94.
BRAN, D; J AYESA; G CECCHI; A MARCOLIN; C LÓPEZ & H MORAGA. 1988. Principales tipos de campos y forrajeras naturales del Noreste de la provincia de Río Negro. Pp. 176-180 en: Estación Experimental Agropecuaria Valle Inferior Convenio provincia de Río Negro. Manual de especies silvestres del Monte rionegrino. INTA.
BRAN, DE; GA CECCHI; JJ GAITÁN; JA AYESA & CR LOPEZ. 2007. Efecto de la severidad de quemado sobre la regeneración de la vegetación en el Monte Austral. Ecol. Austral, 17:123-131.
CECCHI, GA; AI KRÖPFL; NM VILLASUSO & RA DISTEL. 2006. Stemflow and soil water redistribution in intact and disturbed plants of Larrea divaricata in Southern Argentina. Arid Land Res. Manag., 20:209-217.
COOK, JG; TJ HERSHEY & LL IRWIN. 1994. Vegetative response to burning on Wyoming mountain-shrub big game ranges. J.Range Manage., 47:296- 302.
FULS, ER. 1992. Ecosystem modification created by patch-overgrazing in semi-arid grassland. J. Arid Environ., 23:59-69.
GIORGETTI, HD; OA MONTENEGRO; GD RODRÍGUEZ; CA BUSSO; T MONTANI; MA BURGOS ET AL. 1997. The comparative influence of past management and rainfall on range herbaceous standing crop in east-central Argentina: 14 years of observations. J. Arid Environ., 36: 623-637.
HAWKES, CV & VR FLETCHER. 2002. Biological soil crusts in a xeric Florida shrubland: composition, abundance and spatial heterogeneity of crusts with different disturbance histories. Microb. Ecol., 43:1-12.
HEISLER, JL; JM BRIGGS; AK KNAPP; JM BLAIR & A SEERY. 2004. Direct and indirect effects of fire on shrub density and aboveground productivity in a messic grassland. Ecology, 85:2245-2257.
HURLBERT, SH. 1984. Pseudoreplication and the design of ecological experiments. Ecol. Monog., 54:187-211.
INOUYE, RS. 2006. Effects of shrub removal and nitrogen addition on soil moisture in sagebrush steppe. J.Arid Environ., 65:604-618.
KNOOP, WT & BH WALKER. 1985. Interactions of woody and herbaceous vegetation in a southern African savanna. J. Ecol.,73:235-253.
KRÖPFL, AI; GA CECCHI; NM VILLASUSO & RA DISTEL. 2002. The influence of Larrea divaricata on soil moisture and on water status and growth of Stipa tenuis in southern Argentina. J. Arid Environ., 52:29-35.
MAYOR, MD; RM BOÓ; DV PELÁEZ & IR ELÍA. 2003. Seasonal variation of the soil seed bank of grasses in central Argentina as related to grazing and shrub cover. J. Arid Environ., 54:467-477.
MEMMOTT, KL; VJ ANDERSON & SB MONSEN. 1998. Seasonal grazing impact on Cryptogamic crusts in a cold desert ecosystem. J. Range Manage., 51:547-550.
MILCHUNAS, DG & WK LAUENROTH. 1993. Quantitative effects of grazing on vegetation and soils over a global range of environments. Ecol. Monogr., 63:327-366.
MORTON, HL & A MELGOZA. 1991. Vegetation changes following brush control in creosotebush communities. J. Range Manage., 44:133-139.
OESTERHELD, M; J LORETI; M SEMMARTIN & JM PARUELO. 1999. Grazing, fire and climate effects on primary productivity of grasslands and savannas. Pp. 287-306 in: L Walker (ed). Ecosystems of disturbed ground. Elsevier. Amsterdam, Netherlands.
PELÁEZ, DV; RM BOÓ; OR ELIA & MD MAYOR. 2003. Effect of fire on growth of three perennial grasses from central semi-arid Argentina. J. Arid Environ., 55:657-673.
PELÁEZ, DV; RM BOÓ; MD MAYOR & OR ELÍA. 2001. Effect of fire on perennial grasses in central semiarid Argentina. J. Range Manage., 54:617-621.
RICE, EL. 1967. A statistical method for determining quadrat size and adequacy of sampling. Ecology, 48:1047-1049.
RICHBURG, JA; AC DIBBLE & WA PATTERSON III. 2002. Woody invasive species and their role in altering fire regimes of the Northeast and Mid-Atlantic states. Pp. 104-111 in: KEM Galley & TP Wilson (eds.). Proceedings of the Invasive Species Workshop: the Role of Fire in the Control and Spread of Invasive Species. Fire Conference 2000: the First National Congress on Fire Ecology, Prevention and Management. Misc. Publ. No. 11. Tall Timbers Research Station. Tallahassee, FL, USA.
ROSTAGNO, CM; GE DEFOSSE & HF del VALLE. 2006. Postfire vegetation dynamics in three rangelands of Northeastern Patagonia, Argentina. Rangeland Ecol. Manage., 59:163-170.
SALA, OE; RA GOLLUSCIO; WK LAUENROTH & A SORIANO. 1989. Resource partitioning between shrubs and grasses in the Patagonian steppe. Oecologia, 81:501-505.
SANKARAN, M; NP HANAN; RJ SCHOLES; J RATNAM; DJ AUGUSTINE; BS CADE; ET AL. 2005. Determinants of woody cover in African savannas. Nature, 438: 846-849.
SCHWILK, DW & DD ACKERLY. 2005. Is there a cost to resprouting? Seedling growth rate and drought tolerance in sprouting and nonsprouting Ceanothus (Rhamnaceae). Am. J. Bot., 92: 404-410.
SCUTARI, NC; MB BERTILLER & AL CARRERA. 2004. Soil-associated lichens in rangelands of north- eastern Patagonia. Lichen goups and species with potential as bioindicators of grazing disturbance. The Lichenologist, 36:404-412.
SOKAL, RR & FJ ROHLF. 1981. Biometry. The principles and the practice of statistics in biological research. 3a edn. WH Freeman & Co (eds). New York, USA. 858 pp.
SORIANO, A & O SALA. 1983. Ecological strategies in a Patagonian arid steppe. Vegetatio, 56:9-15.
ST CLAIR, LL; BL WEBB; JR JOHANSEN & GT NEBEKER. 1984. Cryptogamic soil crusts: enhancement of seedling establishment in disturbed and undisturbed areas. Recl. and Reveg. Res., 3:129-136.
VALENTIN, C. 1981. Organisations pellicullaires superficielles de quelques sols de regions subdesertique (Agadez-Republique du Niger). Dynamique de formation et consequences sur l’economie en eau. These. Université de Paris VII, U.E.R. de Sciences physiques de la terre, Laboratorie de Pedologie.
VAN AUKEN, OW. 2000. Shrub invasions of north american semiarid grasslands. Annu. Rev. Ecol. Syst., 31:197-215.
WALKER, BH & I NOY MEIR. 1982. Aspects of the stability and resilience of savanna ecosystems. Pp. 577-590 in: BH Huntley & BH Walker (eds). Ecology of tropical savannas. Springer-Verlag. New York, U.S.A.
WHELAN, RJ. 1995. The ecology of fire. Cambridge Univ. Press. Cambridge, UK.
Downloads
Published
How to Cite
Issue
Section
License
Authors retain their rights as follows: 1) by granting the journal the right to its first publication, and 2) by registering the published article with a Creative Commons Attribution License (CC-BY 4.0), which allows authors and third parties to view and use it as long as they clearly mention its origin (citation or reference, including authorship and first publication in this journal). Authors can make other non-exclusive distribution agreements as long as they clearly indicate their origin and are encouraged to widely share and disseminate the published version of their work.
