Lloret F., González-Mancebo J.M. (2011) Altitudinal distribution patterns of bryophytes in the Canary Islands and vulnerability to climate change. Flora: Morphology, Distribution, Functional Ecology of Plants. 206: 769-781.LinkDoi: 10.1016/j.flora.2011.04.007
We report the pattern of bryophyte distribution through the elevation gradient of three Canary Islands (Fuerteventura, Tenerife and Gomera) assessing their vulnerability risk to climate change. We considered a conservative scenario of upslope climatic shift of 200-400. m and a drop in the upper limit of the cloud belt from 1500 to 1000. m. Climate change vulnerability was analyzed from the overlap between the predicted shift in isotherms or cloud-belt edges and the current species range, following the Colwell and colleagues's model.Liverworts show narrower ranges and tend to live at lower elevations than mosses. Perennials and long-lived shuttle species establish in the upper localities. Many perennials and most of the long-lived shuttle species grow in cloud forests. Many annual shuttle species and colonists establish in the lowest localities. Colonists also occupy the harsh summit in the highest islands.In accordance with the Colwell model, most elements of this bryoflora appears vulnerable to rapid climatic change. Upland extinction and contraction challenges the bryoflora on the driest, lowest island Fuerteventura; range-shift gaps do this on the highest island Tenerife. Liverworts tend to be more vulnerable to range-shift gaps; mosses are more vulnerable to upland extinction. On the lowest island, perennials and long-lived shuttle species are more vulnerable to upland extinction; perennials are also vulnerable to range-shift gaps. Colonists are most vulnerable to upland contraction or extinction on the high islands Gomera and Tenerife. Annual shuttle species tend to be more vulnerable to lowland attrition on these high, most humid islands. Many elements of the bryoflora of the upper limit of the cloud forests appear to be vulnerable, while most of the flora of other cloud forest areas presumably will not be so affected, with the exception of the most restricted species.A simple model illustrates the feasibility of preliminary assessments of climate change on organisms which show a lack of published detailed information on their distribution and biology. This assessment gains by incorporating estimates of biological attributes. © 2011 Elsevier GmbH.
Lloret F., Keeling E.G., Sala A. (2011) Components of tree resilience: Effects of successive low-growth episodes in old ponderosa pine forests. Oikos. 120: 1909-1920.LinkDoi: 10.1111/j.1600-0706.2011.19372.x
Recent world-wide episodes of tree dieback have been attributed to increasing temperatures and associated drought. Because these events are likely to become more common, improved knowledge of their cumulative effects on resilience and the ability to recover pre-disturbance conditions is important for forest management. Here we propose several indices to examine components of individual tree resilience based on tree ring growth: resistance (inverse of growth reduction during the episode), recovery (growth increase relative to the minimum growth during the episode), resilience (capacity to reach pre-episode growth levels) and relative resilience (resilience weighted by the damage incurred during the episode). Based on tree ring analyses, we analyzed historical patterns of tree resilience to successive drought-induced low growth periods in ponderosa pine trees growing in unmanaged, remote forests of the Rocky Mountains. Low-growth periods registered in tree rings were related to anomalies in the Palmer drought severity index (PDSI) and were attributed to drought. Independently of the impact of a specific event, subsequent growth after a single low-growth episode was related to the growth prior to the event. Growth performance differed with tree age: young trees were overall more resistant to low-growth periods, but older trees recovered better from more recent events. Regardless of tree age, recently burned sites exhibited lower post-episode growth and lower resistance and resilience than unburned ones. We found mixed evidence for the cumulative effect of past low-growth episodes: overall, greater impacts of a prior event and greater cumulative effects of past low-growth periods caused a decrease in resistance. However, we did not find a progressive decrease in resilience over time in old trees. Our results highlight the value of using a combination of estimators to evaluate the different components of resilience. Specifically, while tree responses to disturbance depend on past disturbance episodes, the response is context-specific and depends on the impact the capacity to recover after disturbance. This suggests that recent increases in forest mortality under current climate trends could relate to thresholds on specific components of resilience (resistance, recovery, resilience itself) rather than to an overall loss of resilience over time. Identifying such thresholds and their underlying mechanisms is a promising area of research with important implications for forest management. © 2011 The Authors.
Peñuelas J., Terradas J., Lloret F. (2011) Solving the conundrum of plant species coexistence: Water in space and time matters most. New Phytologist. 189: 5-8.LinkDoi: 10.1111/j.1469-8137.2010.03570.x
[No abstract available]
Lloret F, Vayreda J, Terradas J (2010) Atles d’espècies llenyoses dels bosos de Catalunya. Notícies de la Institució Catalana d’Història Natural, gener-febrer: 1-2.
Saura-Mas S, Paula S, Pausas JG, Lloret F (2010) Fuel loading and flammability in the Mediterranean Basin woody species with different post-fire regenerative strategies. International Journal of Wildland Fire 19: 783-794.
Keenan T, Serra J, Lloret F, Ninyerola M, Sabaté S (2010) Predicting the future of forests in the Mediterranean under climate change, with niche- and process-based models: CO2 matters!. Global Change Biology 17: 565-579. doi:10.1111/j.13652486.2010.02254.x.
Galiano L., Martínez-Vilalta J., Lloret F. (2010) Drought-Induced Multifactor Decline of Scots Pine in the Pyrenees and Potential Vegetation Change by the Expansion of Co-occurring Oak Species. Ecosystems. 13: 978-991.LinkDoi: 10.1007/s10021-010-9368-8
Episodes of drought-induced tree dieback have been recently observed in many forest areas of the world, particularly at the dry edge of species distributions. Under climate change, those effects could signal potential vegetation shifts occurring over large geographical areas, with major impacts on ecosystem form and function. In this article, we studied the effect of a single drought episode, occurred which in summer 2005, on a Scots pine population in central Pyrenees (NE Spain). Our main objective was to study the environmental correlates of forest decline and vegetation change at the plot level. General and generalized linear models were used to study the relationship between canopy defoliation, mortality and recruitment, and plot characteristics. A drought-driven multifactor dieback was observed in the study forest. Defoliation and mortality were associated with the local level of drought stress estimated at each plot. In addition, stand structure, soil properties, and mistletoe infection were also associated with the observed pattern of defoliation, presumably acting as long-term predisposing factors. Recruitment of Scots pine was low in all plots. In contrast, we observed abundant recruitment of other tree species, mostly Quercus ilex and Q. humilis, particularly in plots where Scots pine showed high defoliation and mortality. These results suggest that an altitudinal upwards migration of Quercus species, mediated by the dieback of the currently dominant species, may take place in the studied slopes. Many rear-edge populations of Scots pine sheltered in the mountain environments of the Iberian Peninsula could be at risk under future climate scenarios. © 2010 Springer Science+Business Media, LLC.
Peñuelas J, Gracia C, Filella I, Jump A, Carnicer J, Coll M, Lloret F, Curiel J, Estiarte M, Rutishauser T, Ogaya R, LLusiá J, Sardans J (2010) Intégration des effets du changement climatique sur les forêts méditerranéennes : observation, expérimentation, modélisation et gestion p. 351. Introducing the climate change effects on Mediterranean forest ecosystems: observation, experimentation, simul ation and management . Forêt Méditerranéenne XXXI, nº 4 pp. 357. ISSN 0245-484X.
Peñuelas J, Filella I, Estiarte M, Ogaya R, Llusià J, Sardans J, Jump A, Curiel J, Carnicer J, Rutishauser T, Rico L, Keenan T, Garbulsky M, Coll M, Díaz de Quijano M, Seco R, Rivas-Ubach A, Silva J, Boada M, Stefanescu C, Lloret F, Terradas J (2010) Impactes, vulnerabilitat i retroalimentacions climàtiques als ecosistemes terrestres catalans. A: Llebot E. (ed). Segon informe sobre el canvi climàtic a Catalunya. Institut d'Estudis Catalans i Generalitat de Catalunya. pp. 373-407.
Loepfe L., Martinez-Vilalta J., Oliveres J., Piñol J., Lloret F. (2010) Feedbacks between fuel reduction and landscape homogenisation determine fire regimes in three Mediterranean areas. Forest Ecology and Management. 259: 2366-2374.LinkDoi: 10.1016/j.foreco.2010.03.009
In densely populated areas like the Mediterranean, wildfire extent is mostly limited by fire suppression and fuel fragmentation. Fire is known to spread more easily through high fuel loads and homogenous terrain and it is supposed to reduce fuel amount and continuity, creating a negative feedback. Here we combine information from administration fire records, satellite imagery fire scars and land use/cover maps to asses the effects of fire on landscape structure and vice versa for three areas in Catalonia (NE Spain). We worked with three spatial focuses: the actual fire scar, 1 km2 squares and 10 km2 squares. In these regions agriculture land abandonment has lead to increased fuel continuity, paralleled by an increment of fire size. We confirm that fire spread is facilitated by land use/cover types with high fuel load and by homogeneous terrain and that fire reduces fuel load by transforming forests into shrublands. But we also found that fire increased landscape homogeneity, creating a positive feedback on fire propagation. We argue that this is possible in landscapes with finer grain than fire alone would create. The lack of discontinuities in the fuel bed diminishes the extinction capacity of fire brigades and increases the risk of large fires. We recommend that fire management should focus more on conservation of the traditional rural mosaic in order to prevent further increases in fuel continuity and fire risk. © 2010 Elsevier B.V. All rights reserved.
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