Riparian forest transpiration under the current and projected Mediterranean climate: Effects on soil water and nitrate uptake

Poblador S., Thomas Z., Rousseau-Gueutin P., Sabaté S., Sabater F. (2019) Riparian forest transpiration under the current and projected Mediterranean climate: Effects on soil water and nitrate uptake. Ecohydrology. 12: 0-0.
Link
Doi: 10.1002/eco.2043

Abstract:

Vegetation plays a key role in riparian area functioning by controlling water and nitrate (N─NO3 −) transfers to streams. We investigated how spatial heterogeneity modifies the influence of vegetation transpiration on soil water and N─NO3 − balances in the vadose soil of a Mediterranean riparian forest. On the basis of field data, we simulated water flow and N─NO3 − transport in three riparian zones (i.e., near-stream, intermediate, and hillslope) using HYDRUS-1D model. We investigated spatiotemporal patterns across the riparian area over a 3-year period and future years using an IPCC/CMIP5 climate projection for the Mediterranean region. Potential evapotranspiration was partitioned between evaporation and transpiration to estimate transpiration rates at the area. Denitrification in the forest was negligible, thus N─NO3 − removal was only considered through plant uptake. For the three riparian zones, the model successfully predicted field soil moisture (θ). The near-stream zone exchanged larger volumes of water and supported higher θ and transpiration rates (666 ± 75 mm) than the other two riparian zones. Total water fluxes, θ, and transpiration rates decreased near the intermediate (536 ± 46 mm transpired) and hillslope zones (406 ± 26 mm transpired), suggesting that water availability was restricted due to deeper groundwater. Transpiration strongly decreased θ and soil N─NO3 − in the hillslope and intermediate zones. Our climate projections highlight the importance of groundwater availability and indicate that soil N─NO3 − would be expected to increase due to changes in plant-root uptake. Lower water availability in the hillslope zone may reduce the effectiveness of N─NO3 − removal in the riparian area, increasing the risk of excess N─NO3 − leaching into the stream. © 2018 John Wiley & Sons, Ltd.

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Effects of past and current drought on the composition and diversity of soil microbial communities

Preece C., Verbruggen E., Liu L., Weedon J.T., Peñuelas J. (2019) Effects of past and current drought on the composition and diversity of soil microbial communities. Soil Biology and Biochemistry. 131: 28-39.
Link
Doi: 10.1016/j.soilbio.2018.12.022

Abstract:

Drought is well known to have strong effects on the composition and activity of soil microbial communities, and may be determined by drought history and drought duration, but the characterisation and prediction of these effects remains challenging. This is because soil microbial communities that have previously been exposed to drought may change less in response to subsequent drought events, due to the selection of drought-resistant taxa. We set up a 10-level drought experiment to test the effect of water stress on the composition and diversity of soil bacterial and fungal communities. We also investigated the effect of a previous long-term drought on communities in soils with different historical precipitation regimes. Saplings of the holm oak, Quercus ilex L., were included to assess the impact of plant presence on the effects of the drought treatment. The composition and diversity of the soil microbial communities were analysed using DNA amplicon sequencing of bacterial and fungal markers and the measurement of phospholipid fatty acids. The experimental drought affected the bacterial community much more than the fungal community, decreasing alpha diversity and proportion of total biomass, whereas fungal diversity tended to increase. The experimental drought altered the relative abundances of specific taxa of both bacteria and fungi, and in many cases these effects were modified by the presence of the plant and soil origin. Soils with a history of drought had higher overall bacterial alpha diversity at the end of the experimental drought, presumably because of adaptation of the bacterial community to drought conditions. However, some bacterial taxa (e.g. Chloroflexi) and fungal functional groups (plant pathogens and saprotrophic yeasts) decreased in abundance more in the pre-droughted soils. Our results suggest that soil communities will not necessarily be able to maintain the same functions during more extreme or more frequent future droughts, when functions are influenced by community composition. Drought is likely to continue to affect community composition, even in soils that are acclimated to it, tending to increase the proportion of fungi and reduce the proportion and diversity of bacteria. © 2018 Elsevier Ltd

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Atmo-ecometabolomics: a novel atmospheric particle chemical characterization methodology for ecological research

Rivas-Ubach A., Liu Y., Steiner A.L., Sardans J., Tfaily M.M., Kulkarni G., Kim Y.-M., Bourrianne E., Paša-Tolić L., Peñuelas J., Guenther A. (2019) Atmo-ecometabolomics: a novel atmospheric particle chemical characterization methodology for ecological research. Environmental Monitoring and Assessment. 191: 0-0.
Link
Doi: 10.1007/s10661-019-7205-x

Abstract:

Aerosol particles play important roles in processes controlling the composition of the atmosphere and function of ecosystems. A better understanding of the composition of aerosol particles is beginning to be recognized as critical for ecological research to further comprehend the link between aerosols and ecosystems. While chemical characterization of aerosols has been practiced in the atmospheric science community, detailed methodology tailored to the needs of ecological research does not exist yet. In this study, we describe an efficient methodology (atmo-ecometabolomics), in step-by-step details, from the sampling to the data analyses, to characterize the chemical composition of aerosol particles, namely atmo-metabolome. This method employs mass spectrometry platforms such as liquid and gas chromatography mass spectrometries (MS) and Fourier transform ion cyclotron resonance MS (FT-ICR-MS). For methodology evaluation, we analyzed aerosol particles collected during two different seasons (spring and summer) in a low-biological-activity ecosystem. Additionally, to further validate our methodology, we analyzed aerosol particles collected in a more biologically active ecosystem during the pollination peaks of three different representative tree species. Our statistical results showed that our sampling and extraction methods are suitable for characterizing the atmo-ecometabolomes in these two distinct ecosystems with any of the analytical platforms. Datasets obtained from each mass spectrometry instrument showed overall significant differences of the atmo-ecometabolomes between spring and summer as well as between the three pollination peak periods. Furthermore, we have identified several metabolites that can be attributed to pollen and other plant-related aerosol particles. We additionally provide a basic guide of the potential use ecometabolomic techniques on different mass spectrometry platforms to accurately analyze the atmo-ecometabolomes for ecological studies. Our method represents an advanced novel approach for future studies in the impact of aerosol particle chemical compositions on ecosystem structure and function and biogeochemistry. © 2019, Springer Nature Switzerland AG.

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We are what we eat: A stoichiometric and ecometabolomic study of caterpillars feeding on two pine subspecies of Pinus sylvestris

Rivas-Ubach A., Peñuelas J., Hódar J.A., Oravec M., Paša-Tolić L., Urban O., Sardans J. (2019) We are what we eat: A stoichiometric and ecometabolomic study of caterpillars feeding on two pine subspecies of Pinus sylvestris. International Journal of Molecular Sciences. 20: 0-0.
Link
Doi: 10.3390/ijms20010059

Abstract:

Many studies have addressed several plant-insect interaction topics at nutritional, molecular, physiological, and evolutionary levels. However, it is still unknown how flexible the metabolism and the nutritional content of specialist insect herbivores feeding on different closely related plants can be. We performed elemental, stoichiometric, and metabolomics analyses on leaves of two coexisting Pinus sylvestris subspecies and on their main insect herbivore; the caterpillar of the processionary moth (Thaumetopoea pityocampa). Caterpillars feeding on different pine subspecies had distinct overall metabolome structure, accounting for over 10% of the total variability. Although plants and insects have very divergent metabolomes, caterpillars showed certain resemblance to their plant-host metabolome. In addition, few plant-related secondary metabolites were found accumulated in caterpillar tissues which could potentially be used for self-defense. Caterpillars feeding on N and P richer needles had lower N and P tissue concentration and higher C:N and C:P ratios, suggesting that nutrient transfer is not necessarily linear through trophic levels and other plant-metabolic factors could be interfering. This exploratory study showed that little chemical differences between plant food sources can impact the overall metabolome of specialist insect herbivores. Significant nutritional shifts in herbivore tissues could lead to larger changes of the trophic web structure. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.

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Urban development versus wetland loss in a coastal Latin American city: Lessons for sustainable land use planning

Rojas C., Munizaga J., Rojas O., Martínez C., Pino J. (2019) Urban development versus wetland loss in a coastal Latin American city: Lessons for sustainable land use planning. Land Use Policy. 80: 47-56.
Link
Doi: 10.1016/j.landusepol.2018.09.036

Abstract:

Urbanization is a primary cause of wetland loss in coastal metropolitan regions. Therefore, it challenges the preservation of biodiversity and the provision of key ecosystem services for urban settlements. These services include leisure and recreation, climate and water regulation, water purification, and especially alleviation of natural hazards. Tsunami flood mitigation is a particularly valuable regulating service provided by these wetlands, as recently evidenced during the 2010 tsunami that hit the central coast of Chile. The Concepción Metropolitan Area (CMA), located on the central coast of Chile, has experienced noticeable wetland loss in recent decades. Our study focused on the Rocuant-Andalién wetland, which has been particularly affected by urbanization. This wetland strongly contributes to flood control, and has provided effective protection against the CMA's latest tsunamis (1835 and 2010). Based on Strategic Environmental Assessment (SEA), we have quantified urban growth over the wetland, both executed and projected under the Metropolitan Urban Plan of Concepción (MUPC). Recent loss in wetland area by urban growth has been quantified using land use and cover change (LUCC) maps from 2004 to 2014, obtained from the classification of Landsat images. Prospective changes (considering the complete MUPC deployment) have been inferred by combining the MUPC with the 2014 land cover map. In addition, we quantified the observed effect and planned urban growth on the wetland protected area, geoforms and potential flooding based on the area affected by the last Tsunami. Results show that urban areas have increased by 28% between 2004 and 2014, while future increase is expected to reach 238%. In contrast, wetland area has decreased by 10% from 2004 to 2014 and is expected to decrease by up to 32 %. Thus, the MUPC is not contributing to the mitigation of wetland loss nor the preservation of its biodiversity and ecosystem services. Implications for coastal planning are discussed. © 2018

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Analytical framework to assess the incorporation of climate change adaptation in water management: Application to the tordera river basin adaptation plan

Sanchez-Plaza A., Broekman A., Paneque P. (2019) Analytical framework to assess the incorporation of climate change adaptation in water management: Application to the tordera river basin adaptation plan. Sustainability (Switzerland). 11: 0-0.
Link
Doi: 10.3390/su11030762

Abstract:

Projections indicate that the Mediterranean region is an area where drastic changes in climate will occur, which will significantly affect water resources. In a context of increasing pressure on water resources as a result of the reduction in water availability, it is essential and urgent to structure water management in a way that allows for adaptation to the challenges that the changing climate will bring to an already water scarce region. It is necessary to generate experiences and methodologies that are based on real case studies that will lay the foundations for the generalisation of practices of climate change adaptation in water management. In this study, we have developed a ready to use analytical framework to evaluate the coherence of water management plans and programs with climate change adaptation principles. We have tested the applicability of the framework that was developed on the Tordera River Basin Adaptation Plan (TRBAP). The analytical framework has proven to be easy to apply and to allow for identifying the inclusion or exclusion of key climate change adaptation features appropriately. We have structured this analytical framework as a starting point contributing to further assessments of how climate change adaptation is incorporated in water management. © 2019 by the authors.

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Responses of forest ecosystems in Europe to decreasing nitrogen deposition

Schmitz A., Sanders T.G.M., Bolte A., Bussotti F., Dirnböck T., Johnson J., Peñuelas J., Pollastrini M., Prescher A.-K., Sardans J., Verstraeten A., de Vries W. (2019) Responses of forest ecosystems in Europe to decreasing nitrogen deposition. Environmental Pollution. : 980-994.
Link
Doi: 10.1016/j.envpol.2018.09.101

Abstract:

Average nitrogen (N) deposition across Europe has declined since the 1990s. This resulted in decreased N inputs to forest ecosystems especially in Central and Western Europe where deposition levels are highest. While the impact of atmospheric N deposition on forests has been receiving much attention for decades, ecosystem responses to the decline in N inputs received less attention. Here, we review observational studies reporting on trends in a number of indicators: soil acidification and eutrophication, understory vegetation, tree nutrition (foliar element concentrations) as well as tree vitality and growth in response to decreasing N deposition across Europe. Ecosystem responses varied with limited decrease in soil solution nitrate concentrations and potentially also foliar N concentrations. There was no large-scale response in understory vegetation, tree growth, or vitality. Experimental studies support the observation of a more distinct reaction of soil solution and foliar element concentrations to changes in N supply compared to the three other parameters. According to the most likely scenarios, further decrease of N deposition will be limited. We hypothesize that this expected decline will not cause major responses of the parameters analysed in this study. Instead, future changes might be more strongly controlled by the development of N pools accumulated within forest soils, affected by climate change and forest management. We find limited indication for response of Europe's forests to declining N deposition. Reactions have been reported for soil solution NO3 − and potentially foliar N concentrations but not for other indicators. © 2018 Elsevier Ltd

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Global photosynthetic capacity is optimized to the environment

Smith N.G., Keenan T.F., Colin Prentice I., Wang H., Wright I.J., Niinemets Ü., Crous K.Y., Domingues T.F., Guerrieri R., Yoko Ishida F., Kattge J., Kruger E.L., Maire V., Rogers A., Serbin S.P., Tarvainen L., Togashi H.F., Townsend P.A., Wang M., Weerasinghe L.K., Zhou S.-X. (2019) Global photosynthetic capacity is optimized to the environment. Ecology Letters. : 0-0.
Link
Doi: 10.1111/ele.13210

Abstract:

Earth system models (ESMs) use photosynthetic capacity, indexed by the maximum Rubisco carboxylation rate (Vcmax), to simulate carbon assimilation and typically rely on empirical estimates, including an assumed dependence on leaf nitrogen determined from soil fertility. In contrast, new theory, based on biochemical coordination and co-optimization of carboxylation and water costs for photosynthesis, suggests that optimal Vcmax can be predicted from climate alone, irrespective of soil fertility. Here, we develop this theory and find it captures 64% of observed variability in a global, field-measured Vcmax dataset for C3 plants. Soil fertility indices explained substantially less variation (32%). These results indicate that environmentally regulated biophysical constraints and light availability are the first-order drivers of global photosynthetic capacity. Through acclimation and adaptation, plants efficiently utilize resources at the leaf level, thus maximizing potential resource use for growth and reproduction. Our theory offers a robust strategy for dynamically predicting photosynthetic capacity in ESMs. © 2019 John Wiley & Sons Ltd/CNRS

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An integrative study of island diversification: Insights from the endemic Haemodracon geckos of the Socotra Archipelago

Tamar K., Simó-Riudalbas M., Garcia-Porta J., Santos X., Llorente G., Vasconcelos R., Carranza S. (2019) An integrative study of island diversification: Insights from the endemic Haemodracon geckos of the Socotra Archipelago. Molecular Phylogenetics and Evolution. 133: 166-175.
Link
Doi: 10.1016/j.ympev.2019.01.009

Abstract:

The Socotra Archipelago in the Arabian Sea is considered one of the most geo-politically isolated landforms on earth and a center of endemism. The archipelago is located at the western edge of the Indian Ocean and comprises four islands: Socotra, Darsa, Samha, and Abd al Kuri. Here we provide an integrative study on Haemodracon geckos, the sole genus of geckos strictly endemic to the archipelago. The sympatric distribution of Haemodracon riebeckii and H. trachyrhinus on Socotra Island provides a unique opportunity to explore evolutionary relationships and speciation patterns, examining the interplay between possible sympatric and allopatric scenarios. We used molecular data for phylogenetic inference, species delimitation analyses, and to infer the diversification timeframe. Multivariate statistics were used to analyze morphological data. Ecological comparisons were explored for macro-niches using species distribution models and observations were used for micro-habitat use. Haemodracon species exhibit great levels of intraspecific genetic diversity. Our calibration estimates revealed that Haemodracon diverged from its closest relative, the mainland genus Asaccus, in the Eocene, before the detachment of the archipelago. The two Haemodracon species diversified in situ on Socotra Island during the Middle Miocene, after the archipelago's isolation, into the two reciprocally monophyletic recognized species. Their divergence is associated mostly with remarkable body size differences and micro-habitat segregation, with low levels of climatic and body shape divergences within their sympatric distributions. These results display how ecological, sympatric speciation, and allopatric speciation followed by secondary contact, may both have varying roles at different evolutionary phases. © 2019 Elsevier Inc.

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Traditional plant functional groups explain variation in economic but not size-related traits across the tundra biome

Thomas H.J.D., Myers-Smith I.H., Bjorkman A.D., Elmendorf S.C., Blok D., Cornelissen J.H.C., Forbes B.C., Hollister R.D., Normand S., Prevéy J.S., Rixen C., Schaepman-Strub G., Wilmking M., Wipf S., Cornwell W.K., Kattge J., Goetz S.J., Guay K.C., Alatalo J.M., Anadon-Rosell A., Angers-Blondin S., Berner L.T., Björk R.G., Buchwal A., Buras A., Carbognani M., Christie K., Siegwart Collier L., Cooper E.J., Eskelinen A., Frei E.R., Grau O., Grogan P., Hallinger M., Heijmans M.M.P.D., Hermanutz L., Hudson J.M.G., Hülber K., Iturrate-Garcia M., Iversen C.M., Jaroszynska F., Johnstone J.F., Kaarlejärvi E., Kulonen A., Lamarque L.J., Lévesque E., Little C.J., Michelsen A., Milbau A., Nabe-Nielsen J., Nielsen S.S., Ninot J.M., Oberbauer S.F., Olofsson J., Onipchenko V.G., Petraglia A., Rumpf S.B., Semenchuk P.R., Soudzilovskaia N.A., Spasojevic M.J., Speed J.D.M., Tape K.D., te Beest M., Tomaselli M., Trant A., Treier U.A., Venn S., Vowles T., Weijers S., Zamin T., Atkin O.K., Bahn M., Blonder B., Campetella G., Cerabolini B.E.L., Chapin III F.S., Dainese M., de Vries F.T., Díaz S., Green W., Jackson R.B., Manning P., Niinemets Ü., Ozinga W.A., Peñuelas J., Reich P.B., Schamp B., Sheremetev S., van Bodegom P.M. (2019) Traditional plant functional groups explain variation in economic but not size-related traits across the tundra biome. Global Ecology and Biogeography. 28: 78-95.
Link
Doi: 10.1111/geb.12783

Abstract:

Aim: Plant functional groups are widely used in community ecology and earth system modelling to describe trait variation within and across plant communities. However, this approach rests on the assumption that functional groups explain a large proportion of trait variation among species. We test whether four commonly used plant functional groups represent variation in six ecologically important plant traits. Location: Tundra biome. Time period: Data collected between 1964 and 2016. Major taxa studied: 295 tundra vascular plant species. Methods: We compiled a database of six plant traits (plant height, leaf area, specific leaf area, leaf dry matter content, leaf nitrogen, seed mass) for tundra species. We examined the variation in species-level trait expression explained by four traditional functional groups (evergreen shrubs, deciduous shrubs, graminoids, forbs), and whether variation explained was dependent upon the traits included in analysis. We further compared the explanatory power and species composition of functional groups to alternative classifications generated using post hoc clustering of species-level traits. Results: Traditional functional groups explained significant differences in trait expression, particularly amongst traits associated with resource economics, which were consistent across sites and at the biome scale. However, functional groups explained 19% of overall trait variation and poorly represented differences in traits associated with plant size. Post hoc classification of species did not correspond well with traditional functional groups, and explained twice as much variation in species-level trait expression. Main conclusions: Traditional functional groups only coarsely represent variation in well-measured traits within tundra plant communities, and better explain resource economic traits than size-related traits. We recommend caution when using functional group approaches to predict tundra vegetation change, or ecosystem functions relating to plant size, such as albedo or carbon storage. We argue that alternative classifications or direct use of specific plant traits could provide new insights for ecological prediction and modelling. © 2018 The Authors Global Ecology and Biogeography Published by John Wiley & Sons Ltd

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