Clearing vs. burning for restoring Pyrenean grasslands after shrub encroachment

C.L. Alados, H. Saiz, P. Nuche, M. Gartzia, B. Komac, Á. de Frutos, Y. Pueyo

Abstract


Anthropogenic activities have modified vegetation on subalpine belts for a long time, lowering the treeline ecotone and influencing the landscape mainly through grazing and fire. The abandonment of these traditional land use practices during the last decades and global warming are contributing largely to the colonization of woody species in subalpine grasslands, causing irreversible changes in ecosystem functioning. A variety of management strategies requiring the use of fire and/or clear-cutting are carried out to prevent the expansion of highly encroaching shrubs and improve the conservation status of subhumid high-productive grasslands ecosystems. However, it is still poorly understood how different management strategies affect the recovery of subalpine grasslands, which is influenced concurrently by the vegetation community involved. In this study we used field experiments to test the impact of management treatments on soil properties and vegetation responses in subalpine Bromion erecti grassland communities colonized by the pyrophyte shrub Echinospartum horridum (Vahl) Rothm. on the southern Pyrenees. Vegetation was monitored for 5 years in E. horridum plots (two plots per treatment) where the vegetation was removed by prescribed fire (Burnt treatment) or by mechanical removal (Clear-cut treatment). Undisturbed E. horridum plots were used as a control (C-Erizón) for shrub removal treatments and a Bromion erecti grassland community regularly grazed (C-Grass) was used as a control for subalpine grassland. Clear-cut treatment of E. horridum community was more effective to control E. horridum colonization than Burnt treatment and contributed to a higher extent to recover original grassland vegetation, because E. horridum seedling performed worse (lower germination rates) and plant species were more similar to the original grassland (legumes, non-legume forbs, and grasses). Shrubs and sub-shrubs cover in Burnt areas increased faster than in Clear-cut areas during the 5 years following the treatment, although it did not reach the level of C-Erizón. Species richness and diversity increased in comparison with C-Erizón in both treatments, but they were significantly lower than those in the C-Grass. Network connectivity was larger in well preserved grasslands, i.e, C-Grass, than in any other treatments, mainly dominated by negative plant-plant association. Soils nutrients declined in Burnt sites 4 years after the fire treatment and no difference was observed between Clear-cut and C-Erizón sites, although they did not reach the soil fertility values of C-Grass in terms of organic matter and C/N ratio. This study showed that grazing favors plant diversity and community complexity in subalpine grasslands. It also demonstrated that clearing is a better strategy than burning to restore grasslands after shrub encroachment because burning entails deeper soil degradation and faster recovering of the pyrophyte shrub, E. horridum.


Keywords


subalpine vegetation; diversity; Echinospartum horridum; grassland restoration; plant-plant association; soil fertility

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References


Aldezabal, A., Moragues, L., Odriozola, I., Mijangos, I. 2015. Impact of grazing abandonment on plant and soil microbial communities in an Atlantic mountain grassland. Applied Soil Ecology 96, 251-260. https://doi.org/10.1016/j.apsoil.2015.08.013.

Alexis, M., Rasse, D., Rumpel, C., Bardoux, G., Pechot, N., Schmalzer, P., Drake, B., Mariotti, A. 2007. Fire impact on C and N losses and charcoal production in a scrub oak ecosystem. Biogeochemistry 82, 201-216. https://doi.org/10.1007/s10533-006-9063-1.

Álvarez-Martínez, J., Gómez-Villar, A., Lasanta, T. 2016. The use of goats grazing to restore pastures invaded by shrubs and avoid desertification: a preliminary case study in the Spanish Cantabrian mountains. Land Degradation & Development 27, 3-13. https://doi.org/10.1002/ldr.2230.

Anderson, V.J., Briske, D.D. 1995. Herbivore-induced species replacement in grasslands: is it driven by herbivory tolerance or avoidance? Ecological Applications 5, 1014-1024. https://doi.org/10.2307/2269351.

André, M.F. 1998. Depopulation, land-use change and landscape transformation in the French Massif Central. Ambio 27, 351-353.

Anthelme, F., Cornillon, L., Brun, J.-J. 2002. Secondary succession of Alnus viridis (Chaix) DC. in Vanoise National Park, France: coexistence of sexual and vegetative strategies. Annals of Forest Science 59, 419-428. https://doi.org/10.1051/forest:2002016.

Armas-Herrera, C.M., Martí, C., Badía, D., Ortiz-Perpiñá, O., Girona-García, A., Porta, J. 2016. Immediate effects of prescribed burning in the Central Pyrenees on the amount and stability of topsoil organic matter. Catena 147, 238-244. https://doi.org/10.1016/j.catena.2016.07.016.

Armas, C., Ordiales, R., Pugnaire, F.I. 2004. Measuring plant interactions: a new comparative index. Ecology 85, 2682-2686. https://doi.org/10.1890/03-0650.

Ayuda, M.I., Pinilla, V. 2002. El proceso de desertización demográfica de la montaña pirenaica en el largo plazo: Aragón. Ager 2, 101-138.

Bardgett, R.D., Wardle, D.A., Yeates, G.W. 1998. Linking above-ground and below-ground interactions: how plant responses to foliar herbivory influence soil organisms. Soil Biology and Biochemistry 30, 1867-1878. https://doi.org/10.1016/S0038-0717(98)00069-8.

Bekker, R.M., Verweij, G.L., Smith, R.E. N., Reiné, R., Bakker, J.P., Schneider S. 1997. Soil seed banks in European grasslands: Does land use affect regeneration perspectives? Journal of Applied Ecology 34, 1293-1310. https://doi.org/10.2307/2405239.

Benito Alonso, J.L. 2006. Vegetación del Parque Nacional de Ordesa y Monte Perdido (Sobrarbe, Pirineo Central Aragonés). Publicaciones del Consejo de Protección de la Naturaleza de Aragón, Zaragoza, pp. 425.

Bossuyt, B., Honnay O. 2008. Can the seed bank be used for ecological restoration? An overview of the seed bank characteristic in European communities. Journal of Vegetation Science 19, 875-884. https://doi.org/10.3170/2008-8-18462.

Callaway, R.M., Brooker, R.W., Choler, P., Kikvidze, Z., Lortie, C.J., Michalet, R., Paolini, L., Pugnaire, F. I., Newingham, B., Aschehoug, E. T., Armas, C., Kikodze, D., Cook, B. J. 2002. Positive interactions among alpine plants increase with stress. Nature 417, 844-848. http://doi.org/10.1038/nature00812.

Callaway, R.M., L. Walker, R. 1997. Competition and facilitation: a synthetic approach to interactions in plant communities. Ecology 78, 1958-1965. https://doi.org/10.1890/0012-9658(1997)078[1958:CAFASA]2.0.CO;2.

Canadell, J., López-Soria, L. 1998. Lignotuber reserves support regrowth following clipping of two Mediterranean shrubs. Functional Ecology 12, 31-38. https://doi.org/10.1093/conphys/cov068.

Canals, R.-M., Pedro, J., Rupérez, E., San-Emeterio, L. 2014. Nutrient pulses after prescribedwinter fires and preferential patterns of N uptakemay contribute to the expansion of Brachypodiumpinnatum (L.) P. Beauv. in highland grasslands. Applied Vegetation Science 17, 419-428. https://doi.org/10.1111/avsc.12088.

Cavieres, L.A., Badano, E.I. 2009. Do facilitative interactions increase species richness at the entire community level? Journal of Ecology 97, 1181-1191. https://doi.org/10.1111/j.1365-2745.2009.01579.x.

Caviezel, C., Hunziker M., Schaffner, M., Kuhn, N.J. 2014. Soil-vegetation interaction on slopes with bush encroachment in the central Alps- adapting slope stability measurements to shifting process domains. Earth Surface Processes and Landforms 39, 509-521. https://doi.org/10.1002/esp.3513.

Clark, P.E., Lee, J., Ko, K., Nielson, R.M., Johnson, D.E., Ganskopp, D.C.,. Pierson, F.B, Hardegree, S.P. 2016. Prescribed fire effects on resource selection by cattle in mesic sagebrush steppe. Part 2: Mid-summer grazing. Journal of Arid Environments 124, 398-412. https://doi.org/10.1016/j.jaridenv.2015.03.005.

Collins, D., Knapp A.K., Briggs, J.M., Blair, J.M., Steinauer, E.M. 1998. Modulation of diversity by grazing and mowing in native tallgrass prairie. Science 280, 745-747. https://doi.org/10.1126/science.280.5364.745.

Cook, J.G., Hershey, T.J., Irwin, L.L. 1994. Vegetation response to burning on Wyoming mountain-shrub big game ranges. Journal of Rangeland Management 47, 296-302. https://doi.org/10.2307/4002550.

Cubit, S. 1996. Burning back with the snow: traditional approaches to grassland management in Tasmania. Australian Geographical Studies 34, 216-224. https://doi.org/10.1111/j.1467-8470.1996.tb00117.x.

Chacón-Labella, J., de la Cruz, M., Escudero, A. 2017. Evidence for a stochastic geometry of biodiversity: the effects of species abundance, richness and intraspecific clustering. Journal of Ecology 105, 382-390. https://doi.org/10.1111/1365-2745.12710.

De Luis, M., Raventós, J., González-Hidalgo, J.C. 2005. Factors controlling seedling germination after fire in Mediterranean gorse shrubland. Implication for fire prescription. Journal of Environmental Management, 76, 159-166. https://doi.org/10.1016/j.jenvman.2005.01.014.

DeGabriel, J.L., Albon, S.D., Fielding, D.A., Riach, D.J., Westaway, S., Irvine, R.J. 2011. The presence of sheep leads to increases in plant diversity and reductions in the impact of deer on heather. Journal of Applied Ecology 48, 1269-1277. https://doi.org/10.1111/j.1365-2664.2011.02032.x.

Fernandes, P.M., Davies, G.M., Ascoli, D., Fernández, C., Moreira, F., Rigolot, E., Stoof, C.R., Vega, J.A. M., Molina, D. 2013. Prescribed burning in southern Europe: developing fire management in a dynamic landscape. Frontier in Ecology and Environment 11, 4-14. https://doi.org/10.1890/120298.

Fernández-Santos, B.J., Gómez-Gutiérrez, M., Tárrega García-Mares, R. 1992. Efectos de quema, corte, arranque, abonado o pastoreo del matorral de escoba blanca (Cytisus multiflorus) sobre la producción y estructura de la comunidad herbácea. Pastos 22, 131-146.

Fernández, C., Vega, J.A., Fontúrbel, T. 2012. The effects of fuel reduction treatments on runoff, infiltration and erosion in two shrubland areas in the north of Spain. Journal of Environmental Management 105, 96-102. 10.1016/j.jenvman.2012.03.048.

Fernández, C., Vega, J.A., Fontúrbel, T., Jiménez, E., Pérez, J.R. 2008. Immediate effects of prescribed burning, chopping and clearing on runoff, infiltration and erosion in a shrubland area in Galicia (NW Spain). Land Degradation & Development 19, 502-515. https://doi.org/10.1002/ldr.855.

Fox, H.V., Bonnet, O., Cromsigt, J.P.G.M., Fritz, H., Shrader, A.M. 2015. Legacy effects of different land-use histories interact with current grazing patterns to determine grazing lawn soil properties. Ecosystems 18, 720-733. https://doi.org/10.1007/s10021-015-9857-x.

Frank, D.A., Evans, R.D. 1997. Effects of native grazers on grassland N cycling in Yellowstone National Park. Ecology 78, 2238-2248. https://doi.org/10.1890/0012-9658(1997)078[2238:EONGOG]2.0.CO;2.

Gartzia, M., Alados, C.L., Perez-Cabello, F. 2014. Assessment of the effects of biophysical and anthropogenic factors on woody plant encroachment in dense and sparse mountain grasslands based on remote sensing data. Progress in Physical Geography 38, 201-217. https://doi.org/10.1177/0309133314524429.

Gehrig-Fasel, J., Guisan, A., Zimmermann, N.E. 2007. Tree line shifts in the Swiss Alps: Climate change or land abandonment? Journal of Vegetation Science 18, 571-582. https://doi.org/10.1111/j.1654-1103.2007.tb02571.x.

Gellrich, M., Baur P., Koch, B., Zimmermann, N.E. 2007. Agricultural land abandonment and natural forest re-growth in the Swiss mountains: A spatially explicit economic analysis. Agriculture, Ecosystems & Environment 118, 93-108. https://doi.org/10.1016/j.agee.2006.05.001.

Goodall, D.W. 1952. Some considerations in the use of point quadrats for the analysis of vegetation. Australian Journal of Sciences Research Bulletin 5, 1-41.

Guisan, A., Theurillat J.P. 2000. Assessing alpine plant vulnerability to climate change: a modeling perspective. Integrated Assessment 1, 307-320. https://doi.org/10.1023/A:1018912114948.

Heanes, D.L. 1984. Determiation of total organic-C in soils by an improved chromic acid digestion and spectrophotometric procedure. Communications in Soil Science and Plant Analysis 15, 1191-1213. https://doi.org/10.1080/00103628409367551.

Hobbs, N.T., Spowart, R.A. 1984. Effects of prescribed fire on nutrition of mountain sheep and mule deer during winter and spring. Journal of Wildlife Management 48, 551-560. https://doi.org/10.2307/3801188.

Hothorn, T., Bretz, F., Westfall, P. 2008. Simultaneous Inference in General Parametric Models. Biometrical Journal 50, 346-363. https://doi.org/10.1002/bimj.200810425.

Kirkpatrick, J.B., Marsden-Smedley, J.B., Di Folco, M.B., Leonard, S.W.J. 2016. Influence of grazing and vegetation type on post-fire floristic and lifeform composition in Tasmania, Australia. Plant Ecology 217, 57-69. https://doi.org/10.1007/s11258-015-0559-4.

Knapp, A.K., Briggs, J.M., Collins, S.L., Archer, S.R., Bret-Harte, M.S., Ewers, B.E., Peters, D.P., Young, D.R., Shaver, G.R., Pendall, E., Cleary, M.B. 2008. Shrub encroachment in North American grasslands: shifts in growth form dominance rapidly alters control of ecosystem carbon inputs. Global Change Biology 14, 615-623. https://doi.org/10.1111/j.1365-2486.2007.01512.x.

Komac, B., Alados, C.L., Camarero, J.J. 2011a. Influence of topography on the colonization of subalpine grasslands by Echinospartum horridum. Artic and Alpine Research 43, 601-611. https://doi.org/10.1657/1938-4246-43.4.601.

Komac, B., Alados, C.L., Bueno, G., Gómez, D. 2011b. Spatial patterns of species distributions in grazed subalpine grasslands. Plant Ecology 212, 519-529. https://doi.org/10.1007/s11258-010-9842-6.

Komac, B., Kefi, S., Nuche, P., Escós, J., Alados, C.L. 2013. Modeling shrub encroachment in subalpine grasslands under different environmental and management scenarios. Journal of Environmental Management 121, 160-169. https://doi.org/10.1016/j.jenvman.2013.01.038.

Körner, C. 2005. The green cover of mountains in a changing environment. In: Huber, U. M., Bugmann, H. K. M., Reasoner, M. A. (Eds.), Global Change and Mountain Regions. Springer, Dordrecht, pp. 367-375.

Körner, C., Paulsen, J. 2004. A world-wide study of high altitude treeline temperatures. Journal of Biogeography 31, 713-732. https://doi.org/10.1111/j.1365-2699.2003.01043.x.

Krahulec, F., Skálová, H., Herben, T., Hadincová, V., Wildová, R., Pecháčková, S. 2001. Vegetation changes following sheep grazing in abandoned mountain meadows. Applied Vegetation Science 4, 97-102. https://doi.org/10.1111/j.1654-109X.2001.tb00239.x.

Lasanta, T., Arnáez, J., Errea, M.P., Ortigosa, L., Ruiz-Flaño, P. 2009. Mountain pastures, environmental degradation, and landscape remediation: The example of a Mediterranean policy initiative. Applied Geography 29, 308-319. https://doi.org/10.1016/j.apgeog.2008.09.006.

Limb, R.F., Fuhlendorf, S.D., Engle, D.M., Miller, R.F. 2016. Synthesis paper: assessment of research on rangeland fire as a management practice. Rangeland Ecology & Management 69, 415-422. https://doi.org/10.1016/j.rama.2016.07.013.

MacDonald, D., Crabtree, J.R., Wiesinger, G., Dax, T., Stamou, N., Fleury, P., Lazpita, J.G, Gibon, A. 2000. Agricultural abandonment in mountain areas of Europe: environmental consequences and policy response. Journal of Environmental Management 59, 47-69. https://doi.org/10.1006/jema.1999.0335.

Martínez-Mena, M., Alvarez, R.J., Castillo, V., Albaladejo, J. 2001. Organic carbon and nitrogen loses influenced by vegetation removal in a semiarid mediterranean soil. Biogeochemistry 61, 309-321. https://doi.org/10.1023/A:1020257208048.

Mayer, R., Kaufmann, R., Vorhauserc, K., Erschbamer, B. 2009. Effects of grazing exclusion on species composition in high-altitude grasslands of the Central Alps. Basic and Applied Ecology 10, 447-455. https://doi.org/10.1016/j.baae.2008.10.004.

McNaughton, S.J., Banyikwa, F.F., McNaughton, M.M. 1997. Promotion of the cycling of diet-enhancing nutrients by African grazers. Science 278, 1798-1800. https://doi.org/10.1126/science.278.5344.1798.

Medina-Roldán, E., Paz-Ferreiro, J., Bardgett, R.D. 2012a. Grazing-induced effects on soil properties modify plant competitive interactions in semi-natural mountain grasslands. Oecologia 170, 159-169. https://doi.org/10.1007/s00442-012-2287-y.

Medina-Roldán, E., Paz-Ferreiro, J., Bardgett, R.D. 2012b. Grazing exclusion affects soil and plant communities, but has no impact on soil carbon storage in an upland grassland. Agriculture, Ecosystems & Environment 149, 118-123. https://doi.org/10.1016/j.agee.2011.12.012.

Melgoza, G., Nowak, R.S., Tausch, R.J. 1990. Soil water exploitation after fire: competition between Bromus tectorum (cheatgrass) and two native species. Oecologia 83, 7-13. https://www.jstor.org/stable/4219288.

Metzger, M.J., Rounsevell, M.D.A., Acosta-Michlik, L., Leemans, R., Schröter, D. 2006. The vulnerability of ecosystem services to land use change. Agriculture, Ecosystems & Environment 114, 69-85. https://doi.org/10.1016/j.agee.2005.11.025.

Michalet, R., Schöb, C., Lortie, C.J., Brooker, R.W., Callaway, R.M. 2014. Partitioning net interactions among plants along altitudinal gradients to study community responses to climate change. Functional Ecology 28, 75-86. https://doi.org/10.1111/1365-2435.12136.

Milchunas, D.G., Lauenroth, W.K. 1993. Quantitative effects of grazing on vegetation and soils over a global range of environments. Ecological Monographs 63, 327-366. https://doi.org/10.2307/2937150.

Milchunas, D.G., Sala, O.E., Lauenroth, W.K. 1988. A generalized model of the effect of grazing by large herbivores on grasslands community structure. The American Naturalist 130, 168-198. https://www.jstor.org/stable/2461755.

Montserrat, P., Fillat, F. 1990. The system of grassland management in Spain. In: Breymeyer, A. I. (Ed), Managed Grasslands Regional Studies. Elsevier, Amsterdam, pp. 37-70.

Moody, J.A., Shakesby, R.A., Robichaud, P.R., Cannon, S.H., Martin, D.A. 2013. Current research issues related topost-wildfire runoff and erosion processes. Earth-Science Reviews 122, 10-37. https://doi.org/10.1016/j.earscirev.2013.03.004.

Moreira, F., Rego, F.C., Ferreira, P.G. 2001. Temporal (1958–1995) pattern of change in a cultural landscape of northwestern Portugal: implications for fire occurrence. Landscape Ecology 16, 557-567. https://doi.org/10.1023/A:1013130528470.

Moreno-de las Heras, M., Diaz-Sierra, R., Turnbull, L., Wainwright, J. 2015. Assessing vegetation structure and ANPP dynamics in a grassland-shrubland Chihuahuan ecotone using NDVI-rainfall relationships. Biogeosciences 12, 2907-2925. https://doi.org/10.5194/bg-12-2907-2015.

Nadal-Romero, E., Otal-Laín, I., Lasanta, T., Sánchez-Navarrete, P., Errea, P., Cammeraat, E. 2018. Woody encroachment and soil carbon stocks in subalpine areas in the Central Spanish Pyrenees. Science of the Total Environment 636, 727-736. https://doi.org/10.1016/j.scitotenv.2018.04.324.

Nigh, R., Diemont, S.A.W. 2013. The Maya milpa: Fire and the legacy of living soil. Frontiers in Ecology and the Environment 11, e45-e54. https://doi.org/10.1890/120344.

Niu, K., He, J.-S., Lechowicz, M.J. 2016. Grazing-induced shifts in community functional composition and soil nutrient availability in Tibetan alpine meadows. Journal of Applied Ecology 53, 1554-1564. https://doi.org/10.1111/1365-2664.12727.

Nuche, P., Gartzia, M., Vilellas, J., Reiné, R., Alados, C.L. 2018. Assessment of prescribed fire and cutting as means of controlling the invasion of subalpine grasslands by Echinospartum horridum. Applied Vegetation Science. https://doi.org/10.1111/avsc.12354.

Öckinger, E., Eriksson, A.K., Smith H.G. 2006. Effects of grassland abandonment, restoration and management on butterflies and vascular plants. Biological Conservation 133, 291-300. https://doi.org/10.1016/j.biocon.2006.06.009.

Odriozola, I., García-Baquero, G., Laskurain, N.A., Aldezabal, A. 2014. Livestock grazing modifies the effect of environmental factors on soil temperature and water content in a temperate grassland. Geoderma 235-236, 347-354. https://doi.org/10.1016/j.geoderma.2014.08.002.

Olofsson, J., Oksanen, L., Callaghan, T., Hulme, P.E., Oksanen, T., Suominen, O. 2009. Herbivores inhibit climate-driven shrub expansion on the tundra. Global Change Biology 15, 2681-2693. https://doi.org/10.1111/j.1365-2486.2009.01935.x.

Pardo, I., Doak, D.F., García-González, R., Gömez, D., García, M.B. 2015. Long-term response of plant communities to herbivore exclusion at high elevation grasslands. Biodiversity and Conservation 24, 3033-3047. https://doi.org/10.1007/s10531-015-0996-3.

Paula, S., Ojeda, F. 2006. Resistance of three co-ocurring resprouter Erica species to highly frequent disturbance. Plant Ecology 183, 329-336. https://doi.org/10.1007/s11258-005-9043-x.

Paula, S., Pausas, J.G. 2008. Burning seeds: germinative response to heat treatments in relation to resprouting ability. Journal of Ecology 96, 543-552. https://doi.org/10.1111/j.1365-2745.2008.01359.x.

Pausas, J.G., Keelay, J.E. 2014. Evolutionary ecology of resprouting and seeding in fire-prone ecosystems. New Phytologist 204, 55-65. https://doi.org/10.1111/nph.12921.

Pausas, J.G., Llovet, J., Rodrigo, A., Vallejo, R. 2008. Are wildfires a disaster in the Mediterranean basin?- A review. International Journal of Wildland Fire 17, 713-723. https://doi.org/10.1071/WF07151.

Pereira, P., Jordán, A., Cerdà, A., Martin, D. 2015. Editorial: the role of ash in fire-affected ecosystems. Catena 135, 10-12. https://doi.org/10.1016/j.catena.2014.11.016.

Peringer, A., Siehoff, S., Chételat, J., Spiegelberger, T., Buttler, A., Gillet, F. 2013. Past and future landscape dynamics in pasture-woodlands of the Swiss Jura Mountains under climate change. Ecology and Society 18, 11. http://doi.org/10.5751/ES-05600-180311.

Pinheiro, J., Bates, D., Debroy, S., Sarkar, D., Team, R.C. 2014. nlme: Linear and nonlinear Mixed Effects Models. R package version 3, 1-117.

Pittarello, M., Probo, M., Lonati, M., Lombardi, G. 2016. Restoration of subalpine srhub-encroached grasslands through pastoral practices: effect on vegetation structure and botanical composition. Applied Vegetation Science 19, 381–390. https://doi.org/10.1111/avsc.12222.

Post, E., Pedersen, C. 2008. Opposing plant community responses to warming with and without herbivores. Procceeding of the National Academy of Sciences 105, 12353–12358. https://doi.org/10.1073/pnas.0802421105.

Price, J., Morgan, J. 2008. Woody plant encroachment reduces species richness of herb-rich woodlands in southern Australia. Austral Ecology 33, 278-289. https://doi.org/10.1111/j.1442-9993.2007.01815.x.

Price, M.V., Waser, N.M. 2000. Responses of subalpine meadow vegetation to four years of experimental warming. Ecological Applications 10, 811-823. https://doi.org/10.2307/2641047.

Raffaele, E., Veblen, T.T. 1998. Facilitation by nurse shrubs of resprouting behavior in a post-fire shrubland in northern Patagonia, Argentina. Journal of Vegetation Science 9, 693-698. https://doi.org/10.2307/3237287.

Rivas, M., Reyes, O., Casal, M. 2006. Influence of heat and smoke on the germination of six leguminous shrubby species. International Journal of Wildland Fire 15, 73-80. https://doi.org/10.1071/WF05008.

Romano, S. 1995. National parks policy and mountain depopulation: a case study in the Abruzzo Region of the Central Apennines, Italy. Mountain Research and Development 15, 121-132. https://doi.org/10.2307/3673876.

Saiz, H., Alados, C.L. 2012. Changes in semi-arid plant species associations along a livestock grazing gradient. Plos One 7, e40551. https://doi.org/10.1371/journal.pone.0091478.

Sala, O.E., Chapin, F.S.I., Armesto, J.J., Berlow, E., Blommfield, J., Dirzo, R., Huber-Sanwald, E., Huenneke, L.F., Jackson, R.B., Leemans, R., Lodge, D.M., Mooney, H.A., Oesterheld, M., Poff, N.L., Sykes, M.T., Walker, B.H., Walker, M., Wall, D.H. 2000. Global biodiversity scenarios for the year 2100. Science 287, 1770-1774. https://doi.org/10.1126/science.287.5459.1770.

San Emeterio, L., Múgica, L., Ugarte, M.D., Goicoa, T., Canals, R.M. 2016. Sustainability of traditional pastoral fires in highlands under global change: Effects on soil function and nutrient cycling. Agriculture, Ecosystems & Environment 235, 155-163. https://doi.org/10.1016/j.agee.2016.10.009.

Sankaran, M., Hanan, N.P., Scholes, R.J., Ratnam, J., Augustine, D.J., Cade, B.S., Gignoux, J., Higgins, S.I., Le Roux, X., Ludwig, F., Ardo, J., Banyikwa, F., Bronn, A., Bucini, G., Caylor, K.K., Coughenour, M.B., Diouf, A., Ekaya, W., Feral, C.J., February, E.C., Frost, P.G.H., Hiernaux, P., Hrabar, H., Metzger, K.L., Prins, H.H.T., Ringrose, S., Sea, W., Tews, J., Worden, J., Zambatis, N. 2005. Determinants of woody cover in African savannas. Nature 438, 846-849. https://doi.org/10.1038/nature04070.

Santín, C.S., Doerr, H. 2016. Fire effects on soils: the human dimension. Philosophical Transactions of The Royal Society B 371, 20150171. https://doi.org/10.1098/rstb.2015.0171.

Semmartin, M., Aguiar, M.R., Distel, R.A., Moretto, A.S., Ghersa C.M. 2004. Litter quality and nutrient cycling affected by grazing-induced species replacements along a precipitation gradient. Oikos 107, 148-160. http://doi.org/10.1111/j.0030-1299.2004.13153.x.

Shakesby, R.A., Doerr, S.H. 2006a. Wildfire as a hydrological and geomorphological agent. Earth-Sciences Reviews 74, 269-307. https://doi.org/10.1016/j.earscirev.2005.10.006.

Shakesby, R.A., Doerr, S.H. 2006b. Wildfire as a hydrological and geomorphological agent. Earth-Sciences Reviews 74, 269-307. https://doi.org/10.1016/j.earscirev.2005.10.006.

Shannon, C.E. 1948. A mathematical theory of communication. Bell System Technical Journal 27, 379-423.

Soliveres, S., Maestre, F.T. 2014. Plant–plant interactions, environmental gradients and plant diversity: A global synthesis of community-level studies. Perspectives in Plant Ecology, Evolution and Systematics 16:154-163. https://doi.org/10.1016/j.ppees.2014.04.001.

Soto, B., Diaz-Fierros, F. 1998. Runoff and soil erosion from areas of burnt scrub: comparison of experimental results with those predicted by the WEPP model. Catena 31, 257-270. https://doi.org/10.1016/S0341-8162(97)00047-7.

Speed, J.D.M., Austrheim, G., Hester, A.J., Mysterud, A. 2012. Elevational advance of alpine plant communities is buffered by herbivory. Journal of Vegetation Science 23, 617-625. https://doi.org/10.1016/S0341-8162(97)00047-7.

Speed, J.D.M., Austrheim G., Mysterud, A. 2013. The response of plant diversity to grazing varies along an elevational gradient. Journal of Ecology 101, 1225-1236. https://doi.org/10.1111/1365-2745.12133.

Speed, J.D.M., Martinsen, V., Mysterud, A., Mulder, J., Holand, Ø., Austrheim, G. 2014. Long-term Iincrease in aboveground carbon stocks following exclusion of grazers and forest establishment in an Alpine ecosystem. Ecosystems of the World 17, 1138-1150. https://doi.org/10.1007/s10021-014-9784-2.

Tasser, E, Tappeiner, U. 2002. Impact of land use changes on mountain vegetation. Applied Vegetation Science 5, 173-184. https://doi.org/10.1111/j.1654-109X.2002.tb00547.x.

Theurillat, J.-P., Guisan, A. 2001. Potential impact of climate change on vegetation in the European Alps: a review. Climatic Change 50, 77-109. https://doi.org/10.1023/A:1010632015572.

Tilman, D., Kareiva, P.M. 1997. Spatial Ecology: The Role of Space in Population Dynamic and Interspecific Interactions. Princeton University Press, NJ, USA.

Tinner, W., Theurillat J.-P. 2003. Uppermost Limit, Extent, and Fluctuations of the Timberline and Treeline Ecocline in the Swiss Central Alps during the Past 11,500 Years. Arctic, Antarctic, and Alpine Research 35, 158-169.

Tirado, R., Pugnaire, F.I. 2005. Community structure and positive interactions in constraining environments. Oikos 111, 437-444. https://doi.org/10.1111/j.1600-0706.2005.14094.x.

Valiente-Banuet, A., Verdú, M. 2008. Temporal shifts from facilitation to competition occur between closely related taxa. Journal of Ecology 96, 489-494. https://doi.org/10.1111/j.1365-2745.2008.01357.x.

van der Wal, R. 2006. Do herbivores cause habitat degradation or vegetation state transition? Evidence from the tundra. Oikos 114, 177 - 186. https://doi.org/10.1111/j.2006.0030-1299.14264.x.

Veen, P., Jefferson, R., de Smith, J., van der Straaten, J. 2009. Grasslands in Europe of high nature value. KNNV Publishing, Zeist (Netherlands), pp. 320.

Vega, J.A., Fernández, C., Fontúrbel, T. 2005. Throughfall, runoff and soil erosion after prescribed burning in gorse shrubland in Galicia (NW Spain). Land Degradation & Development 16, 37-51. https://doi.org/10.1002/ldr.643.

Vilà, M., Lloret, F., Ogheri, E., Terradas, J. 2008. Positive fire-grass feedback in Mediterranean Basin woodlands. Forest Ecology and Management 147, 3-14. https://doi.org/10.1016/S0378-1127(00)00435-7.

Vittoz, P., Randin, C., Dutoit, A., Bonnet, F., Hegg, O. 2009. Low impact of climate change on subalpine grasslands in the Swiss Northern Alps. Global Change Biology 15, 209-220. https://doi.org/10.1111/j.1365-2486.2008.01707.x.

Vittoz, P., Rulence, B., Largey, T., Freléchoux, F. 2008. Effects of Climate and Land-Use Change on the Establishment and Growth of Cembran Pine (Pinus cembra L.) over the Altitudinal Treeline Ecotone in the Central Swiss Alps. Arctic, Antarctic, and Alpine Research 40, 225-232. https://doi.org/10.1657/1523-0430(06-010)[VITTOZ]2.0.CO;2.

WallisDeVries, M.F., Poschlod, P., Willems, J.H. 2002. Challenges for the conservation of calcareous grasslands in northwestern Europe: integrating the requirements of flora and fauna. Biological Conservation 104, 265-273. https://doi.org/10.1016/S0006-3207(01)00191-4.

Wiegand, T., Huth, A., Getzin, S., Wang, X., Hao, Z., Gunatilleke, C.V.S., Gunatilleke, I.A.U.N. 2012. Testing the independent species’ arrangement assertion made by theories of stochastic geometry of biodiversity. Proceedings of the Royal Society B 279, 3312-3320. https://doi.org/10.1098/rspb.2012.0376.

Zavala, L.M., Jordán, A., Gil, J., Bellinfante, N., Pain, C. 2009. Intact ash and charred litter reduces susceptibility to rain splash erosion post-wildfire. Earth Surface Processes and Landforms 34, 1522-1532. https://doi.org/10.1002/esp.1837.

Zuur, A.F., Ieno, E.N., Walker, N.J.K., Saveliev, A.A., Smith, G.M. 2009. Mixed effects models and extensions in Ecology with R. Springer, New York.




DOI: http://dx.doi.org/10.18172/cig.3589

© Universidad de La Rioja, 2013

ISSN 0211-6820

EISSN 1697-9540