Shifting Impacts of Climate Change: Long-Term Patterns of Plant Response to Elevated CO<inf>2</inf>, Drought, and Warming Across Ecosystems

Andresen, L.C., Müller, C., de Dato, G., Dukes, J.S., Emmett, B.A., Estiarte, M., Jentsch, A., Kröel-Dulay, G., Lüscher, A., Niu, S., Peñuelas, J., Reich, P.B., Reinsch, S., Ogaya, R., Schmidt, I.K., Schneider, M.K., Sternberg, M., Tietema, A., Zhu, K., Bilton, M.C. (2016) Shifting Impacts of Climate Change: Long-Term Patterns of Plant Response to Elevated CO2, Drought, and Warming Across Ecosystems. Advances in Ecological Research. : 0-0.
Link
Doi: 10.1016/bs.aecr.2016.07.001

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Soil food web stability in response to grazing in a semi-arid prairie: The importance of soil textural heterogeneity

Andrés P., Moore J.C., Simpson R.T., Selby G., Cotrufo F., Denef K., Haddix M.L., Shaw E.A., de Tomasel C.M., Molowny-Horas R., Wall D.H. (2016) Soil food web stability in response to grazing in a semi-arid prairie: The importance of soil textural heterogeneity. Soil Biology and Biochemistry. 97: 131-143.
Link
Doi: 10.1016/j.soilbio.2016.02.014

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Grazing of grasslands by large herbivores is a form of land use intensification that affects not only plant communities but also soil biota and the ecosystem services that it provides. While grassland ecosystem responses to grazing have been extensively studied, few studies have focused on the effects of aboveground herbivores on belowground diversity and functions. In this work, we quantified effects of grazing on the structure, function and dynamic stability of soil food webs. We sampled a long-term grazing manipulation in a semi-arid shortgrass steppe (USA Great Plains) at sites showing contrasting soil textures. Treatments included native steppe plots that have been moderately grazed since 1939 paired with plots totally protected from grazing since 1996. We sampled our plots for soil C and N, and for soil biota, separated microbes and micro- and mesofauna in trophic functional groups and defined trophic relationships. We used models to estimate carbon and nitrogen mineralization, energy flow throughout the food web, interaction strengths between trophic groups at steady-state and, eventually, asymptotic (near-equilibrium or local) stability (Moore and de Ruiter, 2012). Soil food web response to grazing depended on soil texture and organic matter content. In our food webs, most energy flowed through the fungal and bacterial detritus-based channels (sensu Moore and Hunt, 1988). There was a clear asymmetry between the amount of energy flowing through each of the two channels and, the higher this asymmetry, the higher was food web stability. Stability was affected by both grazing and soil properties (increased under grazing in high clay soils with high organic matter content but decreased in less organic loam sandy soils), and positively associated with soil organic matter content. Overall, we found that the carbon flow through the soil food web of the shortgrass steppe is responsive to grazing in ways that altered stability and that structural, functional, and dynamic attributes are sensitive parameters for evaluating soil response to land use under changing scenarios. © 2016 Elsevier Ltd.

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Relationships among taxonomic, functional, and phylogenetic ant diversity across the biogeographic regions of Europe

Arnan X., Cerdá X., Retana J. (2016) Relationships among taxonomic, functional, and phylogenetic ant diversity across the biogeographic regions of Europe. Ecography. : 0-0.
Link
Doi: 10.1111/ecog.01938

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Understanding how different biodiversity components are related across different environmental conditions is a major goal in macroecology and conservation biogeography. We investigated correlations among alpha and beta taxonomic (TD), phylogenetic (PD), and functional diversity (FD) in ant communities in the five biogeographic regions most representative of western Europe; we also examined the degree of niche conservatism. We combined data from 349 ant communities composed of 154 total species, which were characterized by 10 functional traits and by phylogenetic relatedness. We computed TD, PD, and FD using the Rao quadratic entropy index, which allows each biodiversity component to be partitioned into α and β diversity within the same mathematical framework. We ran generalized least squares and multiple matrix regressions with randomization to investigate relationships among the diversity components. We used Pagel's λ test to explore niche conservatism in each biogeographic region. At the alpha scale, TD was consistently, positively related to PD and FD, although the strength and scatter of this relationship changed among the biogeographic regions. Meanwhile, PD and FD consistently matched up across regions. Accordingly, we found similar degrees of niche conservatism across regions. Nonetheless, these alpha-scale relationships had low coefficients of determination. At the beta scale, the three diversity components were highly correlated across all regions (especially TD and FD, as well as PD and FD). Our results imply that the different diversity components, and especially PD and FD, are consistently related across biogeographic regions and analytical scale. However, the alpha-scale relationships were quite weak, suggesting environmental factors might influence the degree of association among diversity components at the alpha level. In conclusion, conservation programs should seek to preserve functional and phylogenetic diversity in addition to species richness, and this approach should be applied universally, regardless of the biogeographic locations of the sites to be protected. © 2016 Nordic Society Oikos.

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Ordinary and extraordinary movement behaviour of small resident fish within a mediterranean marine protected area

Aspillaga E., Bartumeus F., Linares C., Starr R.M., López-Sanz A., Díaz D., Zabala M., Hereu B. (2016) Ordinary and extraordinary movement behaviour of small resident fish within a mediterranean marine protected area. PLoS ONE. 11: 0-0.
Link
Doi: 10.1371/journal.pone.0159813

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It is important to account for the movement behaviour of fishes when designing effective marine protected areas (MPAs). Fish movements occur across different spatial and temporal scales and understanding the variety of movements is essential to make correct management decisions. This study describes in detail the movement patterns of an economically and commercially important species, Diplodus sargus, within a well-enforced Mediterranean MPA. We monitored horizontal and vertical movements of 41 adult individuals using passive acoustic telemetry for up to one year. We applied novel analysis and visualization techniques to get a comprehensive view of a wide range of movements. D. sargus individuals were highly territorial, moving within small home ranges (< 1 km2), inside which they displayed repetitive diel activity patterns. Extraordinary movements beyond the ordinary home range were observed under two specific conditions. First, during stormy events D. sargus presented a sheltering behaviour, moving to more protected places to avoid the disturbance. Second, during the spawning season they made excursions to deep areas (> 50 m), where they aggregated to spawn. This study advances our understanding about the functioning of an established MPA and provides important insights into the biology and management of a small sedentary species, suggesting the relevance of rare but important fish behaviours. © 2016 Aspillaga et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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Leaf-level photosynthetic capacity in lowland Amazonian and high-elevation Andean tropical moist forests of Peru

Bahar N.H.A., Ishida F.Y., Weerasinghe L.K., Guerrieri R., O'Sullivan O.S., Bloomfield K.J., Asner G.P., Martin R.E., Lloyd J., Malhi Y., Phillips O.L., Meir P., Salinas N., Cosio E.G., Domingues T.F., Quesada C.A., Sinca F., Escudero Vega A., Zuloaga Ccorimanya P.P., del Aguila-Pasquel J., Quispe Huaypar K., Cuba Torres I., Butrón Loayza R., Pelaez Tapia Y., Huaman Ovalle J., Long B.M., Evans J.R., Atkin O.K. (2016) Leaf-level photosynthetic capacity in lowland Amazonian and high-elevation Andean tropical moist forests of Peru. New Phytologist. : 0-0.
Link
Doi: 10.1111/nph.14079

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We examined whether variations in photosynthetic capacity are linked to variations in the environment and/or associated leaf traits for tropical moist forests (TMFs) in the Andes/western Amazon regions of Peru. We compared photosynthetic capacity (maximal rate of carboxylation of Rubisco (Vcmax), and the maximum rate of electron transport (Jmax)), leaf mass, nitrogen (N) and phosphorus (P) per unit leaf area (Ma, Na and Pa, respectively), and chlorophyll from 210 species at 18 field sites along a 3300-m elevation gradient. Western blots were used to quantify the abundance of the CO2-fixing enzyme Rubisco. Area- and N-based rates of photosynthetic capacity at 25°C were higher in upland than lowland TMFs, underpinned by greater investment of N in photosynthesis in high-elevation trees. Soil [P] and leaf Pa were key explanatory factors for models of area-based Vcmax and Jmax but did not account for variations in photosynthetic N-use efficiency. At any given Na and Pa, the fraction of N allocated to photosynthesis was higher in upland than lowland species. For a small subset of lowland TMF trees examined, a substantial fraction of Rubisco was inactive. These results highlight the importance of soil- and leaf-P in defining the photosynthetic capacity of TMFs, with variations in N allocation and Rubisco activation state further influencing photosynthetic rates and N-use efficiency of these critically important forests. © 2016 New Phytologist Trust.

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Matching the phenology of Net Ecosystem Exchange and vegetation indices estimated with MODIS and FLUXNET in-situ observations

Balzarolo M., Vicca S., Nguy-Robertson A.L., Bonal D., Elbers J.A., Fu Y.H., Grünwald T., Horemans J.A., Papale D., Peñuelas J., Suyker A., Veroustraete F. (2016) Matching the phenology of Net Ecosystem Exchange and vegetation indices estimated with MODIS and FLUXNET in-situ observations. Remote Sensing of Environment. 174: 290-300.
Link
Doi: 10.1016/j.rse.2015.12.017

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Shifts in ecosystem phenology play an important role in the definition of inter-annual variability of net ecosystem carbon uptake. A good estimate at the global scale of ecosystem phenology, mainly that of photosynthesis or gross primary productivity (GPP), may be provided by vegetation indices derived from MODIS satellite image data.However, the relationship between the start date of a growing (or greening) season (SGS) when derived from different vegetation indices (VI's), and the starting day of carbon uptake is not well elucidated. Additionally, the validation of existing phenology data with in-situ measurements is largely missing. We have investigated the possibility to use different VI's to predict the starting day of the growing season for 28 FLUXNET sites as well as MODIS data. This analysis included main plant functional types (PFT's).Of all VI's taken into account in this paper, the NDVI (Normalized Difference Vegetation Index) shows the highest correlation coefficient for the relationship between the starting day of the growing season as observed with MODIS and in-situ observations. However, MODIS observations elicit a 20-21 days earlier SGS date compared to in-situ observations. The prediction for the NEE start of the growing season diverges when using different VI's, and seems to depend on the amplitude for carbon and VI and on PFT. The optimal VI for estimation of a SGS date was PFT-specific - for example the WRDVI for cropland, but the MODIS NDVI performed best when applied as an estimator for Net Ecosystem Exchange and when considering all PFT's pooled. © 2015 Elsevier Inc.

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Strong resilience of soil respiration components to drought-induced die-off resulting in forest secondary succession

Barba J., Curiel Yuste J., Poyatos R., Janssens I.A., Lloret F. (2016) Strong resilience of soil respiration components to drought-induced die-off resulting in forest secondary succession. Oecologia. 182: 27-41.
Link
Doi: 10.1007/s00442-016-3567-8

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How forests cope with drought-induced perturbations and how the dependence of soil respiration on environmental and biological drivers is affected in a warming and drying context are becoming key questions. The aims of this study were to determine whether drought-induced die-off and forest succession were reflected in soil respiration and its components and to determine the influence of climate on the soil respiration components. We used the mesh exclusion method to study seasonal variations in soil respiration (RS) and its components: heterotrophic (RH) and autotrophic (RA) [further split into fine root (RR) and mycorrhizal respiration (RM)] in a mixed Mediterranean forest where Scots pine (Pinus sylvestris L.) is undergoing a drought-induced die-off and is being replaced by holm oak (Quercus ilex L.). Drought-induced pine die-off was not reflected in RS nor in its components, which denotes a high functional resilience of the plant and soil system to pine die-off. However, the succession from Scots pine to holm oak resulted in a reduction of RH and thus in an important decrease of total respiration (RS was 36 % lower in holm oaks than in non-defoliated pines). Furthermore, RS and all its components were strongly regulated by soil water content-and-temperature interaction. Since Scots pine die-off and Quercus species colonization seems to be widely occurring at the driest limit of the Scots pine distribution, the functional resilience of the soil system over die-off and the decrease of RS from Scots pine to holm oak could have direct consequences for the C balance of these ecosystems. © 2016, Springer-Verlag Berlin Heidelberg.

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Effects of drought-induced forest die-off on litter decomposition

Barba J., Lloret F., Yuste J.C. (2016) Effects of drought-induced forest die-off on litter decomposition. Plant and Soil. 402: 91-101.
Link
Doi: 10.1007/s11104-015-2762-4

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Aims: Drought-induced forest die-off and subsequent species replacement may modify environmental conditions and eventually affect litter decomposition. We aimed to disentangle the effects of tree species and die-off state on litter decomposition in a mixed forest where Pinus sylvestris populations experiencing severe drought-induced die-off are being replaced by Quercus ilex. Methods: Litter bags with leaves and fine roots from both species were placed under canopies representing three habitats of the die-off and replacement process (healthy and dead P. sylvestris and healthy Q. ilex). Mass was assessed over 3 years. Results: Species-specific chemistry of litter (C:N ratio) had a direct effect on mass loss, but also indirect effects, attributed to the decomposer microbial community associated with a given habitat-species. In their respective original habitats, oak leaves decomposed 44 % faster than pine needles, whereas oak roots decomposed 46 % slower than pine roots. Conclusions: Forest die-off and species replacement affected litter decomposition. This effect can have great implications in forest functioning, particularly if drought-induced die-off worsens in the next decades, according with the trend observed in the studied system. © 2015, Springer International Publishing Switzerland.

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Aclimatación de los bosques al aumento de la sequía: cambios funcionales y estructurales

Barbeta, A. (2016) Aclimatación de los bosques al aumento de la sequía: cambios funcionales y estructurales. Ecosistemas. 25: 144-148.
Link
Doi: 10.7818/ECOS.2016.25-3.19

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Sequence of plant responses to droughts of different timescales: lessons from holm oak (Quercus ilex) forests

Barbeta, A., Peñuelas, J. (2016) Sequence of plant responses to droughts of different timescales: lessons from holm oak (Quercus ilex) forests. Plant Ecology and Diversity. : 1-18.
Link
Doi: 10.1080/17550874.2016.1212288

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