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Studien zur Tütenpflanze

Feuerökologie und Graslandnutzung

Darum gehts: Im Nordosten Patagoniens gibt es fruchtbares Grasland, das für die Weide und Rinderzucht genutzt wird. Die Tütenpflanze kommt dort nativ vor und wird durch Feuer im Wachstum und der Verbreitung gefördert. Durch häufige Feuer, welche durch die zunehmenden Dürren durch die Klimaveränderung zunehmen, ist davon auszugehen, dass auch die Tütenpflanze sich weiter ausbreitet und wirtschaftlich produktives Grasland verdrängt. Im Gegensatz zu den Gräsern gilt die Tütenpflanze als wenig geeignetes Rinderfutter.

Studienort: San Ramón ranch, 30 km östlich von Bariloche (Provinz Río Negro, NW-Patagonien), Argentinien (41°03'19S, 71°01'50W). Die Ranch umfasst 23 846 ha und liegt am Fusse der Anden. Das Klima ist gemässigt mit mediterran verteilten Niederschlägen. 60% fallen zwischen Mai und August, der jährliche Niederschlag beträgt 580 mm. Die Durchschnittstemperaturen liegen bei 7 °C, im Januar 22 °C, im Juli -3 °C. Während des ganzen Jahres gibt es starke W-NW Winde.

Vegetation: Stipa speciosa dominiert in den tiefer gelegenen Teilen der Ranch, Festuca pallescens in den höher gelegenen Teilen. Zwischendurch wachsen zerstreut Sträucher von Senecio bracteolatus und Mulinum spinosum. An einigen Stellen wachsen einheimische Pflanzen wie Fabiana imbricata und Discaria articulata. An Bäumen gibt es zudem Austrocedrus chilensis.

"1 Introduction


In the forest - steppe ecotone of northwestern Patagonia - vegetation patterns are strongly influenced by fire (Veblen and Lorenz, 1987), topography, substrate type and possibly the depth of water tables (anchorena and Cingolani, 2002). Here, fire regime and environmental heterogeneity create a vegetation mosaic of grasslands and Fabiana imbricata shrublands (Ghermandi et al., 2004). In this region, for the last 100 years, fire regime has been affected by climate variation, related to ENSO phenomena, and also by human land use (Veblen et al., 1999; Kitzberger et al., 2005). Precipitation exceeds the normal average during El Niño years producing higher rates of vegetation growth and consequently higher fuel accumulation. After this, the occurrence of a drier phase of La Niña will dry the fuel favouring the occurence and spread of intense and severe fires (Veblen et al., 1992; Ghermandi et al., 2004). Extensive fires have occurred in northwestern Patagonia after three El Niño events followed by a strong La Niña event since 1972 to 1999 (National Weather Service Climate Prediction Centre, 2008; Ghermandi, unpublished.

Fabiana imbricata is a shrub characteristic of the Northwestern patagonian ecotone and that is frequently found in rocky substrates, and also drainage lines and streams, suggesting that it may be a facultative phreatophyte (Anchorena and Cingolani, 2002). This obligate seeder species recruits new individuals after a disturbance (Ghermandi et al., 2010) forming coeataneous shrublands (Ruete, 2006). According go this, high rates of F. imbricata recruitment were detected after a severe fire followed by a wet spring and models suggest that this is the best situation for the growth of F. imbricata shrublands, also at different fire frequencies (Ghermandi et al., 2010). Global climate change models suggest an increase in the frequency and amplitude of the ENSO phenomena and for this more recruitment windows could be expected for F. imbricata.

Northwestern Patagonian grasslands are the most productive of the region and the main source for cattle and sheep breeding. Frequent fires could stimulate F. imbricata encroachment which means a setback for grassland palatable species and, therefore, a decrease in the forage availability, thus a consequential reduction of the stocking capacity.

The main objective of this study is to determine, at a landscape scale, the spatial dynamics of F. imbricata shrublands in response to fire using GIS and remote-sensing tools, and dendrochronology techniques in northwestern Patagonian grasslands."

"2.2 Species description

Fabiana imbricata Ruiz et Pavón (Solanaceae), is a native evergreen shrub, characterised by its longevity (approx. 150 years) and which is 1.5-3 m tall. Its geographical distribution ranges from Mendoza to the center of Chubut in Argentina, and from Atacama to Valdivia in Chile. This species has stems with a high density of imbricata leaves and it has axillary flowers situated in axillary or terminal brnaches. Its fruit is a septicide capsule of 6 mm which contains main reniform seeds of approx. 0.0-1.2 mm, which have reticulate seed coat (Correa et al., 1971; Gonzalez, 2002). The flowering period extends from September to January. This species forms persistent seed pools in the soil (Gonzalez and Ghermandi, 2008) and its regeneration after a fire depends on seedling production (obligate seeder). The aerial parts of F. imbricata are used for medicinal purposes as a diuretic, digestive agent and th reliev kidney ailments (Razmilic et al., 1994) but it has no value as forage specie for cattle and sheep breeding. This species produce well-demarcated growth rings that can be easily identified (Barichivich et al., 2009)."

Zitierte Quellen:

  • Anchorena, J. Cingolani, A. (2002): Identifying habitat types in a disturbed area of the forest-steppe ecotone of Patagonia, Plant Ecol. 158(1): 97-112.
  • Barichivich et al. (2009): Climate signals in high elevation tree-rings from the semiarid Andes of north-central Chile: responses to regional and large-scale variability. Palaeogeogr. Palaeocl. 281(3-4): 320-333.
  • Correa et al. (1971): Flora patagónica. Inta.
  • Ghermandi et al. (2004): Early post-fire succession in northwestern Patagonia grasslands. J. Veg. Sci. 15(1): 67-76.
  • Ghermandi et al. (2010): Non-linear ecological processes, fires, environmental heterogeneity and shrub invasion in northwestern Patagonia. Ecol. Model. 221(1): 113-121.
  • Gonzalez (2002): Quelle nicht angegeben
  • Gonzalez & Ghermandi (2008): Postfire seed bank dynamics in semiarid grassland, Plant Ecol. 199(2): 175-185.
  • Kitzberger et al. (2005): Variable community responses to herbivory in fire-altered landscapes of northern Patagonia, Argentina. Afr. J. Range For. Sci. 22(2): 85-91.
  • National Weather Service Climate Prediction Centre (2008): Quelle nicht angegeben
  • Razmilic et al. (1994): Rutin and scopoletin content and micropropagation of Fabiana imbricata. Planta Medica 60: 140.
  • Ruete, A. (2006): Arbustización en la estepa? Efectos de disturbios en la dinámica de matorrales de Fabiana imbricata en el noroeste de la Patagonia. Bariloche, Universidad Nacional del Comahue.
  • Veblen & Lorenz (1987): Post-fire stand development of Austrocedrus-Nothofagus forests in northern Patagonia. Plant Ecol. 71(2): 113-126.
  • Veblen et al. (1992): Disturbance and forest dynamics along a transect from Andean rain forest to Patagonian shrubland. J. Veg. Sci. 3(4): 507-520.
  • Veblen et al. (1999): Fire history in northern Patagonia: the roles of humans and climatic variation. Ecol. Monogr. 69(1): 47-67.


  • Oddi, F.J. Dudinszky, N. Ghermandi, L. (2010): Spatial dynamics of Fabiana imbricata shrublands in northwestern Patagonia in relation to natural fires. Natural Hazards and Earth System Sciences 10: 957-966. doi:10.5194/nhess-10-957-2010. (PDF (https://www.nat-hazards-earth-syst-sci.net/10/957/2010/nhess-10-957-2010.pdf))

--davX Literatur 06:53, 16. Okt 2018 (CEST)

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