Seasonal diet composition of Pyrenean chamois is mainly shaped by primary production waves

Espunyes J., Bartolomé J., Garel M., Gálvez-Cerón A., Aguilar X.F., Colom-Cadena A., Calleja J.A., Gassó D., Jarque L., Lavín S., Marco I., Serrano E. (2019) Seasonal diet composition of Pyrenean chamois is mainly shaped by primary production waves. PLoS ONE. 14: 0-0.
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Doi: 10.1371/journal.pone.0210819

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In alpine habitats, the seasonally marked climatic conditions generate seasonal and spatial differences in forage availability for herbivores. Vegetation availability and quality during the growing season are known to drive life history traits of mountain ungulates. However, little effort has been made to understand the association between plant phenology and changes in the foraging strategies of these mountain dwellers. Furthermore, this link can be affected by the seasonal presence of livestock in the same meadows. The objective of this work was to study the seasonal changes in diet composition of Pyrenean chamois (Rupicapra p. pyrenaica) and its relationship to primary production trends in a Mediterranean alpine environment. Moreover, diet composition in two populations with contrasting livestock pressure was compared in order to study the effect of sheep flocks on the feeding behaviour of chamois. From 2009 to 2012, monthly diet composition was estimated by cuticle microhistological analysis of chamois faeces collected in the eastern Pyrenees. The primary production cycle was assessed by remote sensing, using the Normalized Difference Vegetation Index. Additionally, the diet of sheep sharing seasonally the subalpine and alpine meadows with chamois was analysed. Diet selection of chamois and sheep and their overlap was also assessed. Our results show an intra-annual variation in the diet composition of Pyrenean chamois and demonstrate a strong relationship between plant consumption dynamics and phenology in alpine areas. In addition, Calluna vulgaris, Cytisus spp. and Festuca spp., as well as forbs in the summer, are found to be key forage species for Pyrenean chamois. Furthermore, this study couldn’t detect differences between both chamois populations despite the presence of sheep flocks in only one area. However, the detection of a shift in the diet of chamois in both areas after the arrival of high densities of multi-specific livestock suggest a general livestock effect. In conclusion, Pyrenean chamois are well adapted to the variations in the seasonal availability of plants in alpine habitats but could be disturbed by the seasonal presence of livestock. Due to the key plants in their diet, we suggest that population management programmes should focus on the preservation of mixed grasslands composed of patches of shrubs and herbs. The effects of climate change and shrub expansion should be studied as they may potentially affect chamois population dynamics through changes in habitat composition and temporal shifts in forage availability. © 2019 Espunyes 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.

Llegeix més

Different effects of alpine woody plant expansion on domestic and wild ungulates

Espunyes J., Lurgi M., Büntgen U., Bartolomé J., Calleja J.A., Gálvez-Cerón A., Peñuelas J., Claramunt-López B., Serrano E. (2019) Different effects of alpine woody plant expansion on domestic and wild ungulates. Global Change Biology. 25: 1808-1819.
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Doi: 10.1111/gcb.14587

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Changes in land-use and climate affect the distribution and diversity of plant and animal species at different spatiotemporal scales. The extent to which species-specific phenotypic plasticity and biotic interactions mediate organismal adaptation to changing environments, however, remains poorly understood. Woody plant expansion is threatening the extent of alpine grasslands worldwide, and evaluating and predicting its effects on herbivores is of crucial importance. Here, we explore the impact of shrubification on the feeding efficiency of Pyrenean chamois (Rupicapra p. pyrenaica), as well as on the three most abundant coexisting domestic ungulate species: cattle, sheep and horses. We use observational diet composition from May to October and model different scenarios of vegetation availability where shrubland and woodland proliferate at the expense of grassland. We then predicted if the four ungulate species could efficiently utilize their food landscapes with their current dietary specificities measuring their niche breath in each scenario. We observed that the wild counterpart, due to a higher trophic plasticity, is less disturbed by shrubification compared to livestock, which rely primarily on herbaceous plants and will be affected 3.6 times more. Our results suggest that mixed feeders, such as chamois, could benefit from fallow landscapes, and that mountain farmers are at a growing economic risk worldwide due to changing land-use practices and climate conditions. © 2019 John Wiley & Sons Ltd

Llegeix més

Evidence of high individual variability in seed management by scatter-hoarding rodents: does ‘personality’ matter?

Feldman M., Ferrandiz-Rovira M., Espelta J.M., Muñoz A. (2019) Evidence of high individual variability in seed management by scatter-hoarding rodents: does ‘personality’ matter?. Animal Behaviour. 150: 167-174.
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Doi: 10.1016/j.anbehav.2019.02.009

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The predation and dispersal of seeds by scatter-hoarding animals is one of the most studied processes in the context of animal–plant interactions. Seed management by these animals has been traditionally approached at the population level: the patterns documented in the field are assumed to be similar for all individuals of the population and the variability within the population is considered to be random noise. However, little is known about to what extent this variability responds to different and consistent behaviours between individuals. The aim of this study was to analyse the individual variation and consistency in behaviour of scatter-hoarding rodents within a population. As our model we used the wood mouse, Apodemus sylvaticus, a key disperser of holm oak acorns, Quercus ilex, which, in turn, suffers high predation pressure by the common genet, Genetta genetta. In two sets of laboratory experiments, we compared the variance and consistency in behaviours and acorn management due to individual differences with that due to manipulation, using genet scents, of the perceived predation risk. Genet scents reduced the activity (i.e. time out of the refuge) in all wood mice, but the differences and consistency in activity between individuals accounted for most of the variance. Also, mice showed different and consistent stress or relaxed behaviours. Most of the variance in seed management variables, such as dispersal distance and seed size selection, was explained by consistent differences between individuals across scent treatments. The increase in stress behaviours and decrease in relaxed behaviours were positively related to dispersal ability (i.e. longer distances and larger acorns). Our study highlights the importance of considering the individual component of behaviour in scatter-hoarding rodents. This fine-scale level, largely overlooked in the ecological framework, will help to increase our understanding of seed management by scatter-hoarding animals. © 2019 The Association for the Study of Animal Behaviour

Llegeix més

Sea spray influences water chemical composition of Mediterranean semi-natural springs

Fernández-Martínez M., Margalef O., Sayol F., Asensio D., Bagaria G., Corbera J., Sabater F., Domene X., Preece C. (2019) Sea spray influences water chemical composition of Mediterranean semi-natural springs. Catena. 173: 414-423.
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Doi: 10.1016/j.catena.2018.10.035

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Sea spray aerosol (SSA) is responsible for the large-scale transfer of particles from the sea to the land, leading to significant deposition of a range of ions, predominantly Na+, K+, Mg2+ Ca2+, and Cl−. Up to now, there has been little research into the effects of SSA on spring water chemistry. Therefore, we sampled 303 semi-natural springs across Catalonia (NE Iberian Peninsula) and analysed the concentrations of 20 different ions and elements, and determined the impact of SSA (using distance to the coast as a proxy) as well as climate, lithology and human disturbances. We found that distance to the coast had a clear effect on the water chemical composition of springs, while accounting for potentially confounding factors such as anthropogenic water pollution (nitrate, NO3 −), differences in lithology and annual rainfall. Our results showed that springs located closer to the coast had higher Cl−, SO4 2−, Na+, Mg2+, K+ and Ca2+ concentrations than those of springs located further away. Precipitation was generally negatively correlated with the concentration of almost all elements analysed. The concentration of NO3 − increased with distance to the coast, concurrently with farming activities, located mainly inland in the study area. These results demonstrate that SSA has an important effect on the groundwater of coastal zones, up to a distance of around 70 km from the coastline. This analysis reveals the main natural and human processes that influence spring water chemistry in this Mediterranean region, information that could be helpful in similar regions for ecological studies, water quality policies, and for the improvement of predictions in the current context of global change. © 2018 Elsevier B.V.

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Global trends in carbon sinks and their relationships with CO2 and temperature

Fernández-Martínez M., Sardans J., Chevallier F., Ciais P., Obersteiner M., Vicca S., Canadell J.G., Bastos A., Friedlingstein P., Sitch S., Piao S.L., Janssens I.A., Peñuelas J. (2019) Global trends in carbon sinks and their relationships with CO2 and temperature. Nature Climate Change. 9: 73-79.
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Doi: 10.1038/s41558-018-0367-7

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Elevated CO2 concentrations increase photosynthesis and, potentially, net ecosystem production (NEP), meaning a greater CO2 uptake. Climate, nutrients and ecosystem structure, however, influence the effect of increasing CO2. Here we analysed global NEP from MACC-II and Jena CarboScope atmospheric inversions and ten dynamic global vegetation models (TRENDY), using statistical models to attribute the trends in NEP to its potential drivers: CO2, climatic variables and land-use change. We found that an increased CO2 was consistently associated with an increased NEP (1995–2014). Conversely, increased temperatures were negatively associated with NEP. Using the two atmospheric inversions and TRENDY, the estimated global sensitivities for CO2 were 6.0 ± 0.1, 8.1 ± 0.3 and 3.1 ± 0.1 PgC per 100 ppm (~1 °C increase), and −0.5 ± 0.2, −0.9 ± 0.4 and −1.1 ± 0.1 PgC °C−1 for temperature. These results indicate a positive CO2 effect on terrestrial C sinks that is constrained by climate warming. © 2018, The Author(s), under exclusive licence to Springer Nature Limited.

Llegeix més

A synthesis of bias and uncertainty in sap flow methods

Flo V., Martinez-Vilalta J., Steppe K., Schuldt B., Poyatos R. (2019) A synthesis of bias and uncertainty in sap flow methods. Agricultural and Forest Meteorology. 271: 362-374.
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Doi: 10.1016/j.agrformet.2019.03.012

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Sap flow measurements with thermometric methods are widely used to measure transpiration in plants. Different method families exist depending on how they apply heat and track sapwood temperature (heat pulse, heat dissipation, heat field deformation or heat balance). These methods have been calibrated for many species, but a global assessment of their uncertainty and reliability has not yet been conducted. Here we perform a meta-analysis of 290 individual calibration experiments assembled from the literature to assess calibration performance and how this varies across methods, experimental conditions and wood properties (density and porosity types). We used different metrics to characterize mean accuracy (closeness of the measurements to the true, reference value), proportional bias (resulting from an effect of measured flow on the magnitude of the error), linearity in the relationship between measurements and reference values, and precision (reproducibility and repeatability). We found a large intra- and inter-method variability in calibration performance, with a low proportion of this variability explained by species. Calibration performance was best when using stem segments. We did not find evidence of strong effects of wood density or porosity type in calibration performance. Dissipation methods showed lower accuracy and higher proportional bias than the other methods but they showed relatively high linearity and precision. Pulse methods also showed significant proportional bias, driven by their overestimation of low flows. These results suggest that Dissipation methods may be more appropriate to assess relative sap flow (e.g., treatment effects within a study) and Pulse methods may be more suitable to quantify absolute flows. Nevertheless, all sap flow methods showed high precision, allowing potential correction of the measurements when a study-specific calibration is performed. Our understanding of how sap flow methods perform across species would be greatly improved if experimental conditions and wood properties, including changes in wood moisture, were better reported. © 2019 Elsevier B.V.

Llegeix més

Agricultural soil organic carbon stocks in the north-eastern Iberian Peninsula: Drivers and spatial variability

Funes I., Savé R., Rovira P., Molowny-Horas R., Alcañiz J.M., Ascaso E., Herms I., Herrero C., Boixadera J., Vayreda J. (2019) Agricultural soil organic carbon stocks in the north-eastern Iberian Peninsula: Drivers and spatial variability. Science of the Total Environment. 668: 283-294.
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Doi: 10.1016/j.scitotenv.2019.02.317

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Estimating soil organic carbon (SOC) stocks under agriculture, assessing the importance of their drivers and understanding the spatial distribution of SOC stocks are crucial to predicting possible future SOC stocks scenarios under climate change conditions and to designing appropriate mitigation and adaptation strategies. This study characterized and modelled SOC stocks at two soil depth intervals, topsoil (0–30 cm) and subsoil (30–100 cm), based on both legacy and recent data from 7245 agricultural soil profiles and using environmental drivers (climate, agricultural practices and soil properties) for agricultural soils in Catalonia (NE Spain). Generalized Least Square (GLS) and Geographical Weighted Regression (GWR) were used as modelling approaches to: (i) assess the main SOC stock drivers and their effects on SOC stocks; (ii) analyse spatial variability of SOC stocks and their relationships with the main drivers; and (iii) predict and map SOC stocks at the regional scale. While topsoil variation of SOC stocks depended mainly on climate, soil texture and agricultural variables, subsoil SOC stocks changes depended mainly on soil attributes such us soil texture, clay content, soil type or depth to bedrock. The GWR model revealed that the relationship between SOC stocks and drivers varied spatially. Finally, the study was only able to predict and map topsoil SOC stocks at the regional scale, because controlling factors of SOC stocks at the subsoil level were largely unavailable for digital mapping. According to the resulting map, the mean SOC stock value for Catalan agriculture at the topsoil level was 4.88 ± 0.89 kg/m 2 and the total magnitude of the carbon pool in agricultural soils of Catalonia up to 30 cm reached 47.9 Tg. The present study findings are useful for defining carbon sequestration strategies at the regional scale related with agricultural land use changes and agricultural management practices in a context of climate change. © 2019 Elsevier B.V.

Llegeix més

A quantitative assessment of mid-term risks of global change on forests in Western Mediterranean Europe

Gil-Tena A., Morán-Ordóñez A., Comas L., Retana J., Vayreda J., Brotons L. (2019) A quantitative assessment of mid-term risks of global change on forests in Western Mediterranean Europe. Regional Environmental Change. 19: 819-831.
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Doi: 10.1007/s10113-018-1437-0

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Assessment of potential forests’ threats due to multiple global change components is urgently needed since increasing exposure to them could undermine their future persistence. We aim to assess the risks to the persistence of monospecific forests in Western Mediterranean Europe posed by climate change, fire, and land-use changes (i.e., deforestation) in the short and medium terms (horizon 2040). We specifically evaluate whether the degree of risk related to the likelihood of hazard occurrence varies depending on seral stage, tree species, and climate gradients. We performed the risk assessment on forests of Catalonia (NE Spain) through a combination of correlative and process-based modeling approaches and future global change scenarios. Overall, climate suitability of forests showed a general decrease by 2040, with the exception of xeric Pinus halepensis forests mainly distributed in the driest climate of the study area. Forest stands dominated by low drought-tolerant species were at higher risk of losing climatic suitability than forests dominated by Mediterranean species. The highest fire and deforestation risks were predicted for forest stands in dry climate where human pressures are higher. Nevertheless, high deforestation risk was also attained outside the driest areas. Deforestation risk was lower in old-growth than in younger stands, whereas old-growth forests in the Wet climate or dominated by Pinus sylvestris were projected to be at higher fire risk than younger forests. Our results suggest that conservation actions should target forest stands in dry climate. Moreover, old-growth forest stands should also be prioritized due to their particular sensitivity to disturbances and their high ecological value. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.

Llegeix més

Encroachment of shrubs into subalpine grasslands in the Pyrenees modifies the structure of soil fungal communities and soil properties

Grau O., Saravesi K., Ninot J.M., Geml J., Markkola A., Ahonen S.H., Peñuelas J. (2019) Encroachment of shrubs into subalpine grasslands in the Pyrenees modifies the structure of soil fungal communities and soil properties. FEMS microbiology ecology. 95: 0-0.
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Doi: 10.1093/femsec/fiz028

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The encroachment of shrubs into grasslands is common in terrestrial ecosystems dominated by grass. Land abandonment and favourable climatic trends in recent decades have favoured the expansion of shrubs into subalpine grasslands in many mountainous regions across Europe. The advance of the succession from grassland to shrubland is expected to have a major impact on ecosystem functioning. We used DNA metabarcoding to assess whether the structure of soil fungal communities varied along the succession from subalpine grassland to shrubland in the Pyrenees, and investigated whether shrub encroachment was associated with changes in soil properties. The expansion of shrubs increased the soil C:N ratio and/or reduced the N, P or K contents. Plant-driven changes in soil properties were strongly associated with the compositional turnover of fungi, including arbuscular mycorrhizal, ectomycorrhizal, ericoid, root endophytic, saprotrophic, lichenised and pathogenic fungi. Total richness and the richness of most functional groups were correlated with soil P, N and the C:N or N:P ratios. We show that the interplay between abiotic factors (changes in soil properties) and biotic factors (occurrence and identity of shrubs) played a key role in the structure and uniqueness of soil fungal communities along the succession. © FEMS 2019.

Llegeix més

Temperature and masting control Norway spruce growth, but with high individual tree variability

Hacket-Pain A., Ascoli D., Berretti R., Mencuccini M., Motta R., Nola P., Piussi P., Ruffinatto F., Vacchiano G. (2019) Temperature and masting control Norway spruce growth, but with high individual tree variability. Forest Ecology and Management. 438: 142-150.
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Doi: 10.1016/j.foreco.2019.02.014

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Tree growth and reproduction are subject to trade-offs in resource allocation. At the same time, they are both influenced by climate. In this study, we combined long records of reproductive effort at the individual- (29 years), population- (41 years) and regional (up to 53 years) scale, and tree ring chronologies, to investigate the effects of climate and reproductive allocation on radial growth in an Alpine Norway spruce forest. Seed and cone production was highly variable between years (mean individual CV = 1.39, population CV = 1.19), but showed high reproductive synchrony between individuals (mean inter-tree correlation = 0.72). No long-term trend in reproductive effort was detected over four decades of observations. At the stand scale, cone production was dominated by a small number of individuals (“super-producers”), who remained dominant over three decades. Individual tree growth responded positively to summer temperature, but the response to cone production varied between individual trees. Consequently, we found some evidence that mast years were associated with a divergence in growth between high and low cone producing individuals, and a decline in within-population growth synchrony. At the population level we found limited evidence of a relationship between growth and reproduction. Radial growth was lower than average in some mast years, but not in others. This was partly explained by summer temperature during the year of growth, with growth reductions restricted to mast years that coincided with colder than average summers. Regional mast records and tree ring chronologies provided some support to indicate that our results were consistent in other spruce stands, although the effect of mast years on growth appeared to vary between sites. Tree ring variation at the individual and population level, and between-tree growth synchrony are influenced by masting, and consequently dendrochronologists should consider both the occurrence of masting and the individual differences in reproductive effort when interpreting tree ring datasets. Our results also indicate that tree ring chronologies contain information to facilitate reconstruction of mast events, which will help address outstanding questions regarding the future response of masting to climate change. © 2019 Elsevier B.V.

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