Abundance and morphometry changes across the high-mountain lake-size gradient in the tropical Andes of Southern Ecuador

Mosquera, P.V., Hampel, H., Vázquez, R.F., Alonso, M., Catalan, J. (2017) Abundance and morphometry changes across the high-mountain lake-size gradient in the tropical Andes of Southern Ecuador. Water Resources Research. 53: 7269-7280.
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Doi: 10.1002/2017WR020902

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Drivers of genetic differentiation in a generalist insect-pollinated herb across spatial scales

Muñoz-Pajares, A.J., García, C., Abdelaziz, M., Bosch, J., Perfectti, F., Gómez, J.M. (2017) Drivers of genetic differentiation in a generalist insect-pollinated herb across spatial scales. Molecular Ecology. : 0-0.
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Doi: 10.1111/mec.13971

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Growth and water use performance of four co-occurring riparian tree species in a Mediterranean riparian forest

Nadal-Sala D., Sabaté S., Sánchez-Costa E., Poblador S., Sabater F., Gracia C. (2017) Growth and water use performance of four co-occurring riparian tree species in a Mediterranean riparian forest. Forest Ecology and Management. 396: 132-142.
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Doi: 10.1016/j.foreco.2017.04.021

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Mediterranean riparian zones act as vegetation shelters for several deciduous tree species at the edge of their bioclimatic distribution, e.g. alder (Alnus glutinosa), black poplar (Populus nigra) or ash (Fraxinus excelsior). Current global warming and human induced disturbances may worsen their growing conditions. Under such circumstances, black locust (Robinia pseudoacacia) is outcompeting autochthonous tree species. Here, we provide evidences of black locust better growth and water use performance than alder and ash. We compare the temporal and spatial patterns of transpiration and the stem basal area increments of alder, black poplar, common ash and black locust, all of them co-occurring in a mixed riparian Mediterranean forest. Black locust presented the lowest transpiration values per basal area unit (4.0 mm·m−2·growing season−1). Although tree transpiration was mainly driven by energy availability instead of water, ash transpiration was constrained by water availability at soil water contents below 0.08 cm3·cm−3. Black locust was the only tree species growing all over the water availability gradient present in the study site, and it did not present any significant difference in sap flow values across this gradient. Furthermore, black locust and black poplar were the species with higher growth-based water use efficiency (5.4 g·cm−1·m−3 and 3.6 g·cm−1·m−3, respectively); ash and alder were the less efficient ones (2.8 g·cm−1·m−3 and 1.9 g·cm−1·m−3respectively). The good performance of black locust is relevant to understand its great successful invasion of Mediterranean riparian forests, particularly after human-induced disturbances, as forest management. © 2017 Elsevier B.V.

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Ecological impacts of atmospheric pollution and interactions with climate change in terrestrial ecosystems of the Mediterranean Basin: Current research and future directions

Ochoa-Hueso R., Munzi S., Alonso R., Arróniz-Crespo M., Avila A., Bermejo V., Bobbink R., Branquinho C., Concostrina-Zubiri L., Cruz C., Cruz de Carvalho R., De Marco A., Dias T., Elustondo D., Elvira S., Estébanez B., Fusaro L., Gerosa G., Izquieta-Rojano S., Lo Cascio M., Marzuoli R., Matos P., Mereu S., Merino J., Morillas L., Nunes A., Paoletti E., Paoli L., Pinho P., Rogers I.B., Santos A., Sicard P., Stevens C.J., Theobald M.R. (2017) Ecological impacts of atmospheric pollution and interactions with climate change in terrestrial ecosystems of the Mediterranean Basin: Current research and future directions. Environmental Pollution. 227: 194-206.
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Doi: 10.1016/j.envpol.2017.04.062

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Mediterranean Basin ecosystems, their unique biodiversity, and the key services they provide are currently at risk due to air pollution and climate change, yet only a limited number of isolated and geographically-restricted studies have addressed this topic, often with contrasting results. Particularities of air pollution in this region include high O3 levels due to high air temperatures and solar radiation, the stability of air masses, and dominance of dry over wet nitrogen deposition. Moreover, the unique abiotic and biotic factors (e.g., climate, vegetation type, relevance of Saharan dust inputs) modulating the response of Mediterranean ecosystems at various spatiotemporal scales make it difficult to understand, and thus predict, the consequences of human activities that cause air pollution in the Mediterranean Basin. Therefore, there is an urgent need to implement coordinated research and experimental platforms along with wider environmental monitoring networks in the region. In particular, a robust deposition monitoring network in conjunction with modelling estimates is crucial, possibly including a set of common biomonitors (ideally cryptogams, an important component of the Mediterranean vegetation), to help refine pollutant deposition maps. Additionally, increased attention must be paid to functional diversity measures in future air pollution and climate change studies to establish the necessary link between biodiversity and the provision of ecosystem services in Mediterranean ecosystems. Through a coordinated effort, the Mediterranean scientific community can fill the above-mentioned gaps and reach a greater understanding of the mechanisms underlying the combined effects of air pollution and climate change in the Mediterranean Basin. © 2017 Elsevier Ltd

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Fire behavior in Pinus halepensis thickets: Effects of thinning and woody debris decomposition in two rainfall scenarios

Palmero-Iniesta M., Domènech R., Molina-Terrén D., Espelta J.M. (2017) Fire behavior in Pinus halepensis thickets: Effects of thinning and woody debris decomposition in two rainfall scenarios. Forest Ecology and Management. 404: 230-240.
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Doi: 10.1016/j.foreco.2017.08.043

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Thinning is recommended in overstocked thickets to improve forest structure and reduce high-intensity stand replacing fires. Many studies have outlined the benefits of thinning for forest growth and reproduction but effectiveness in fire intensity needs more attention. Moreover, the effect that slash generated by thinning may have on fire behavior has been seldom explored. Here we simulated fire behavior on unthinned and thinned Aleppo pine (Pinus halepensis) thickets in Catalonia (Northeast Spain) where woody residues were left in situ. Furthermore, we simulated fire behavior one year later considering the reduction in the dead fuel load, using decomposition rates empirically determined under high and low rainfall. We could also assess the accuracy of our simulations by measuring fire severity on trees in the same study area after a real wildfire. Simulations predicted that thinning prevents the occurrence of active crown fires and reduces mean flame length (from 6.2 ± 0.8 to 1.5 ± 0.2 m), the rate of fire spread (from 5.4 ± 0.9 to 0.9 ± 0.1 m min−1) and the fireline intensity (from 3631 ± 686 to 446 ± 70 kW m−1) compared to unthinned thickets. In the thinned stands these parameters further decrease one year later owing to the decomposition of woody residues. Decomposition of woody residues was observed to be faster under a high rainfall scenario leading to a reduction in simulated flame length and fire intensity twice as fast as under low rainfall. In accordance with the lack of active crown fires and the lower flame length predicted for thinned thickets, fire severity observed after a real wildfire in the study area was lower in thinned than in unthinned stands (respectively, 2.02 ± 0.13 vs. 2.93 ± 0.15 in a scale of 0–4). The agreement between simulations that predicted a reduction in fire intensity in thinned thickets and the lower fire damage (fire severity) observed confirms the benefits of thinning young P. halepensis thickets to reduce fire effects. Moreover, our results indicate that leaving woody residues in situ after the thinning of these young thickets does not increase fire intensity. Yet, the influence of precipitation on the decomposition of woody residues highlights the uncertainties that an increase in drought in Mediterranean-type climates may have in the behavior of future fire events. © 2017 Elsevier B.V.

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Climate change impacts on water availability and human security in the intercontinental biosphere reserve of the mediterranean (Morocco-Spain)

Pascual D., Pla E., Fons-Esteve J., Abdul-Malak D. (2017) Climate change impacts on water availability and human security in the intercontinental biosphere reserve of the mediterranean (Morocco-Spain). Environmental Change and Human Security in Africa and the Middle East. : 75-93.
Link
Doi: 10.1007/978-3-319-45648-5_4

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The Mediterranean basin has been identified as one of the world most vulnerable regions to global change effects. Global and regional climate change scenarios foresee an increase in the average annual temperature over the planet’s mean. These scenarios project an increasing frequency of drought episodes adding to the complexity of water scarcity management and questioning the future sustainability of water resource uses. This study assesses the potential water vulnerability in the Intercontinental Biosphere Reserve of the Mediterranean (IBRM), located in the western side of the Mediterranean Basin between Spain (Europe) and Morocco (Africa). The vulnerability assessment proposes an innovative and multidisciplinary approach based on the use of climate change scenarios, a hydro-ecological model and the participation of stakeholders and local experts in expert meetings. Future scenarios draw a more arid climate for the IBRM, with more frequent water scarcity phenomena. A reduction of around 28.1-30.3 % is expected in stream flows by 2070. Agricultural water demands are expected to increase between 7.5 and 16 % in the Moroccan side in order to maintain the current production standards, whereas Spanish pastures are expected to maintain current productions with no need of supplementary water supply. Within forests, tree covered areas showed a higher potential vulnerability to future climate change than shrublands proving higher adaptation to arid conditions. Finally, the tourism will be impacted by the increase in summer temperature and in water supply shortages. Moreover, a significant spatial segregation of impacts is observed. Higher altitudes will be less affected by climate change and changes may be relevant to biodiversity but not to human activities. On the contrary, lower altitudes and coastal areas will experience an increasing water demand to sustain different uses by the end of the century in a higher water scarcity context. © Springer International Publishing Switzerland 2017.

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Tropical insect diversity: Evidence of greater host specialization in seed-feeding weevils

Peguero, G., Bonal, R., Sol, D., Muñoz, A., Sork, V.L., Espelta, J.M. (2017) Tropical insect diversity: Evidence of greater host specialization in seed-feeding weevils. Ecology. : 0-0.
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Doi: 10.1002/ecy.1910

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Revisiting the open-field test: what does it really tell us about animal personality?

Perals, D., Griffin, A.S., Bartomeus, I., Sol, D. (2017) Revisiting the open-field test: what does it really tell us about animal personality?. Animal Behaviour. 123: 69-79.
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Doi: 10.1016/j.anbehav.2016.10.006

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Weakening temperature control on the interannual variations of spring carbon uptake across northern lands

Piao S., Liu Z., Wang T., Peng S., Ciais P., Huang M., Ahlstrom A., Burkhart J.F., Chevallier F., Janssens I.A., Jeong S.-J., Lin X., Mao J., Miller J., Mohammat A., Myneni R.B., Peñuelas J., Shi X., Stohl A., Yao Y., Zhu Z., Tans P.P. (2017) Weakening temperature control on the interannual variations of spring carbon uptake across northern lands. Nature Climate Change. 7: 359-363.
Link
Doi: 10.1038/nclimate3277

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Ongoing spring warming allows the growing season to begin earlier, enhancing carbon uptake in northern ecosystems. Here we use 34 years of atmospheric CO 2 concentration measurements at Barrow, Alaska (BRW, 71° N) to show that the interannual relationship between spring temperature and carbon uptake has recently shifted. We use two indicators: the spring zero-crossing date of atmospheric CO 2 (SZC) and the magnitude of CO 2 drawdown between May and June (SCC). The previously reported strong correlation between SZC, SCC and spring land temperature (ST) was found in the first 17 years of measurements, but disappeared in the last 17 years. As a result, the sensitivity of both SZC and SCC to warming decreased. Simulations with an atmospheric transport model coupled to a terrestrial ecosystem model suggest that the weakened interannual correlation of SZC and SCC with ST in the last 17 years is attributable to the declining temperature response of spring net primary productivity (NPP) rather than to changes in heterotrophic respiration or in atmospheric transport patterns. Reduced chilling during dormancy and emerging light limitation are possible mechanisms that may have contributed to the loss of NPP response to ST. Our results thus challenge the â € warmer spring-bigger sink' mechanism. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

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On the causes of trends in the seasonal amplitude of atmospheric CO<inf>2</inf>

Piao, S., Liu, Z., Wang, Y., Ciais, P., Yao, Y., Peng, S., Chevallier, F., Friedlingstein, P., Janssens, I.A., Peñuelas, J., Sitch, S., Wang, T. (2017) On the causes of trends in the seasonal amplitude of atmospheric CO2. Global Change Biology. : 0-0.
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Doi: 10.1111/gcb.13909

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