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  • 1
    Language: English
    In: Environmental modelling & software : with environment data news, 2017-03, Vol.89, p.190-195
    Description: Daily precipitation datasets are usually large, bulky and hard to handle, but they are of key importance in many environmental studies. We developed a tool to create custom datasets from observed daily precipitation records. Reference values (RV) are computed for each day and location using multivariate logistic regression with altitude, latitude and longitude as covariates. The operations were compiled in an Open Source R package called reddPrec. The reddPrec package consists of a set of functions used to: i) apply a comprehensive quality control over original daily precipitation datasets, flagging suspect data based on five predefined criteria; ii) fill missing values in original data series by estimating precipitation values using the 10 nearest observations for each day; and iii) create new series and gridded datasets in locations where no data were recorded. •A daily precipitation reconstruction method is compiled in an Open Source R package.•Three functions are provided to apply quality control, fill gaps and create grids.•Users are able to obtain complete datasets and estimate new data at ungauged locations.
    Subject(s): Daily precipitation ; reddPrec ; Missing values ; Quality control ; Grid ; Precipitation (Meteorology)
    ISSN: 1364-8152
    E-ISSN: 1873-6726
    Source: ScienceDirect Journals
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  • 2
    Language: English
    In: Journal of biogeography, 2018-05, Vol.45 (5), p.1126-1139
    Description: Aim We investigate the effects of the environmental and geographical processes driving growth resilience and recovery in response to drought in Mediterranean Pinus pinaster forests. We explicitly consider how intraspecific variability modulates growth resilience to drought. Location Western Mediterranean basin. Methods We analysed tree rings from a large network of 48 forests (836 trees) encompassing wide ecological and climatic gradients, including six provenances. To characterize the major constraints of P. pinaster growth under extremely dry conditions, we simulated growth responses to temperature and soil moisture using a process‐based growth model coupled with the quantification of climate–growth relationships. Then, we related growth–resilience indices to provenance and site variables considering different drought events. Results Pinus pinaster displayed strong variation in growth resilience across its distributional range, but common patterns were found within each provenance. Post‐drought resilience increased with elevation and drier conditions but decreased with spring precipitation. Trees from dry sites were less resistant to drought but recovered faster than trees from wet sites. Main conclusions Resilience strategies differed among tree provenances: wet forests showed higher growth resistance to drought, while dry forests presented faster growth recovery, suggesting different impacts of climate warming on forest productivity. We detected geographically structured resilience patterns corresponding to different provenances, confirming high intraspecific variability in response to drought. This information should be included in species distribution models to simulate forest responses to climate warming and forecasted aridification.
    Subject(s): drought resistance ; drought stress ; resilience indices ; forward growth models ; dendroecology ; provenances ; post‐drought recovery ; Dendroclimatology ; Precipitation (Meteorology) ; Soil moisture ; Droughts ; Analysis
    ISSN: 0305-0270
    E-ISSN: 1365-2699
    Source: Alma/SFX Local Collection
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  • 3
    Language: English
    In: Ecological monographs, 2018-05-01, Vol.88 (2), p.141-169
    Description: Over the past 15 years, 3 million hectares of forests have been converted into shrublands or grasslands in the Mediterranean countries of the European Union. Fire and drought are the main drivers underlying this deforestation. Here we present a conceptual framework for the process of fire-induced deforestation based on the interactive effects of fire and drought across three hierarchical scales: resistance in individuals, resilience in populations, and transitions to a new state. At the individual plant level, we review the traits that confer structural and physiological resistance, as well as allow for resprouting capacity: deforestation can be initiated when established individuals succumb to fire. After individuals perish, the second step toward deforestation requires a limited resilience from the population, that is, a reduced ability of that species to regenerate after fire. If individuals die after fire and the population fails to recover, then a transition to a new state will occur.We document trade-offs between drought survival and fire survival, as embolism resistance is negatively correlated with fire tolerance in conifers and leaf shedding or drought deciduousness, a process that decreases water consumption at the peak of the dry season, temporally increases crown flammability. Propagule availability and establishment control resilience after mortality, but different hypotheses make contrasting predictions on the drivers of post-fire establishment. Mycorrhizae play an additional role in modulating the response by favoring recovery through amelioration of the nutritional and water status of resprouts and new germinants. So far, resprouter species such as oaks have provided a buffer against deforestation in forests dominated by obligate seeder trees, when present in high enough density in the understory. While diversifying stands with resprouters is often reported as advantageous for building resilience, important knowledge gaps exist on how floristic composition interacts with stand flammability and on the "resprouter exhaustion syndrome," a condition where pre-fire drought stress, or short fire return intervals, seriously restrict post-fire resprouting. Additional attention should be paid to the onset of novel fire environments in previously fire-free environments, such as high altitude forests, and management actions need to accommodate this complexity to sustain Mediterranean forests under a changing climate.
    Subject(s): REVIEWS ; state and transition ; Mediterranean forests ; drought ; community dynamics ; land degradation ; stress physiology ; fire ; climate change ; Deforestation ; New York ; Netherlands ; Global temperature changes ; Droughts ; Physiological aspects ; United Kingdom ; Forests and forestry ; Australia ; Germany ; Spain
    ISSN: 0012-9615
    ISSN: 1557-7015
    E-ISSN: 1557-7015
    Source: Wiley Online Library All Journals
    Source: Alma/SFX Local Collection
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  • 4
    Language: English
    In: International journal of climatology, 2021-01, Vol.41 (S1), p.E2015-E2030
    Description: The long‐term hydroclimatic variability in Santiago (Chile) was analysed by means of a new 481‐year (1536–2016 CE) tree‐ring reconstruction of the Standardized Precipitation Evapotranspiration Index (SPEI) of August, integrating the hydroclimatic conditions during the preceding 14 months. Results show a high frequency of extreme drought events in the late 20th and early 21st centuries, while the frequency of extreme wet events was higher in the 17th–18th centuries. The mid‐20th century represents a breaking point for the hydroclimatic history in the region, including some significant changes: (a) the interannual variability increased; (b) the wet events became less intense; (c) the extreme dry events became more frequent; and (d) the most intense dry event of the entire period was identified, coinciding with the so‐called Megadrought (2006–2016). A correlation analysis between the reconstructed SPEI and three climate indices (PDO, SOI and Niño3.4) was performed at monthly scale, considering different multi‐annual aggregations. The analysis shows diverse impacts on the hydroclimatic variability, with positive correlations between SPEI and PDO as well as Niño3.4, and negative correlations between SPEI and SOI. The most significant correlations were, overall, found at multi‐annual time scales (〉7 years). Results help to better understand the current hydroclimatic changes (Megadrought) in a long‐term context. The long‐term hydroclimatic variability in Santiago (Chile), analysed by means of a 481‐year (1536–2016 CE) tree‐ring reconstruction of the Standardized Precipitation Evapotranspiration Index (SPEI) of August, shows a great temporal variability with higher frequency of extreme drought events in the late 20th and early 21st centuries. The most intense dry event of the whole period was identified, coinciding with the so‐called Megadrought (2006–2016).
    Subject(s): megadrought ; Chile ; tree‐ring ; SPEI
    ISSN: 0899-8418
    E-ISSN: 1097-0088
    Source: Alma/SFX Local Collection
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  • 5
    Language: English
    In: Drying technology, 2017-02-17, Vol.35 (3), p.281-299
    Description: A steady-state, three-dimensional, multiphase computational fluid dynamics (CFD) modeling of a pilot-plant countercurrent spray drying tower is carried out to study the drying behavior of detergent slurry droplets. The software package ANSYS Fluent is employed to solve the heat, mass, and momentum transfer between the hot gas and the polydispersed droplets/particles using the Eulerian-Lagrangian approach. The continuous-phase turbulence is modeled using the differential Reynolds stress model. The drying kinetics is modeled using a single-droplet drying model, which is incorporated into the CFD code using user-defined functions (UDFs). Heat loss from the insulated tower wall to the surrounding is modeled by considering thermal resistances due to deposits on the inside surface, wall, insulation, and outside convective film. For the particle-wall interaction, the restitution coefficient is specified as a constant value as well as a function of particle moisture content. It is found that the variation in the value of restitution coefficient with moisture causes significant changes in the velocity, temperature, and moisture profiles of the gas as well as the particles. Overall, a reasonably good agreement is obtained between the measured and predicted powder temperature, moisture content, and gas temperature at the bottom and top outlets of the tower; considering the complexity of the spray drying process, simplifying assumptions made in both the CFD and droplet drying models and the errors associated with the measurements.
    Subject(s): spray drying kinetics ; Countercurrent spray drying ; heat and mass transfer ; multiphase CFD modeling ; Moisture content ; Heat
    ISSN: 0737-3937
    E-ISSN: 1532-2300
    Source: Academic Search Ultimate
    Source: © ProQuest LLC All rights reserved〈img src="https://exlibris-pub.s3.amazonaws.com/PQ_Logo.jpg" style="vertical-align:middle;margin-left:7px"〉
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  • 6
    Language: English
    In: International journal of climatology, 2018-09, Vol.38 (11), p.4211-4224
    Description: A comprehensive analysis of the spatial and temporal variability of daily precipitation in Spain in the period 1950–2012 was carried out based on the high‐resolution gridded data set SPREAD at a 5 × 5 km spatial resolution. Temporal trends of 12 daily precipitation indices were computed by application of the Sen's slope and the Mann–Kendall tests. The spatial distribution of the trends showed (a) a global slight increase in the duration of the precipitation events, especially along the Mediterranean fringe; (b) an increase of the frequency of low precipitation events and a decrease of the frequency of high and very high events (inverse in the Mediterranean coast); and (c) a slight decrease of the intensity when considering single events (1‐ or 5‐day duration), but a significant negative trend in mean and median precipitation when considering all the precipitation days (p 〉 0), especially in the Mediterranean coast. Daily precipitation trends are useful to understand the behaviour of important events such as the mean and longest periods of rainfall or droughts, which are of key importance in environmental risks. Based on a high‐resolution daily gridded precipitation data set covering Spain over the period 1950–2012, we show that daily precipitation has decreased in intensity and frequency and has slighter increased in duration. Overall, the daily precipitation in Spain has evolved to a less intense precipitation events with a longer duration.
    Subject(s): climate variability ; trends ; daily precipitation ; Spain ; Precipitation variability ; Analysis ; Precipitation (Meteorology)
    ISSN: 0899-8418
    E-ISSN: 1097-0088
    Source: Alma/SFX Local Collection
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  • 7
    Language: English
    In: Remote sensing (Basel, Switzerland), 2021-02-18, Vol.13 (4), p.757
    Description: The influence of soil water content on Aleppo pine growth variability is analyzed against climatic variables, using satellite and modeled soil moisture databases. The study was made with a dendrochronological series of 22 forest sites in Spain with different environmental conditions. From the results of the correlation analysis, at both daily and monthly scales, it was observed that soil moisture was the variable that correlated the most with tree growth and the one that better identified the critical periods for this growth. The maximum correlation coefficients obtained with the rest of the variables were less than half of that obtained for soil moisture. Multiple linear regression analysis with all combinations of variables indicated that soil moisture was the most important variable, showing the lowest p-values in all cases. While identifying the role of soil moisture, it was noted that there was appreciable variability between the sites, and that this variability is mainly modulated by water availability, rather than thermal conditions. These results can contribute to new insights into the ecohydrological dynamics of Aleppo pine and a methodological approach to the study of many other species.
    Subject(s): Aleppo pine ; tree growth ; soil moisture ; climatic factors
    ISSN: 2072-4292
    E-ISSN: 2072-4292
    Source: Academic Search Ultimate
    Source: Directory of Open Access Journals
    Source: ProQuest Central
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  • 8
    Language: English
    In: European journal of forest research, 2019, Vol.138 (2), p.299-312
    Description: Forests exhibit strategies to cope with climate change; however, the rate of the changes on forests can be slower than the actual changes in environmental conditions. Forest management policies, such as assisted migration, may help forests to adapt their species distribution to changing climate conditions. Nonetheless, it certainly requires a better knowledge of climate influences on trees to ensure the success of specific management actions. In this study, we apply dendroclimatological methods to investigate the growth response of the main forest species present in Moncayo Natural Park to climate to assess their current relationship and to model these responses over the potential distribution of each species across the study area. Our results revealed large differences in the response of beech, pine and Pyrenean oak to prevailing climate factors and indicated species-specific patterns of climate sensitivity. The general importance of summer conditions for tree growth was confirmed. In addition, we found directional trends in correlation with specific climate factors along spatial gradients; these results are consistent with the autoecology of the studied species. Based on these findings, we present a new model approach that can serve as a key tool for forest managers to design forest communities that are more stable during climatic change.
    Subject(s): GAMs ; Forest management ; Climate ; Tree growth ; Dendrochronology ; Life Sciences ; Forestry ; Plant Sciences ; Plant Ecology
    ISSN: 1612-4669
    E-ISSN: 1612-4677
    Source: Academic Search Ultimate
    Source: Alma/SFX Local Collection
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  • 9
    Language: English
    In: Trees (Berlin, West), 2013-08, Vol.27 (4), p.927-936
    Description: Tree-ring widths (RW), earlywood (EW) and latewood (LW) widths, the transition from early to latewood (T) and the occurrence of intra-annual density fluctuations in EW (E-ring) and in LW (L-ring), as well as the presence of resin canals in EW and LW, were analyzed in Aleppo pine (Pinus halepensis Mill.) from three sites in Spain and one in Slovenia to find out if the anatomical characteristics can provide additional seasonal climate–growth information from contrasted environmental conditions. Principal component analysis was applied to elucidate the relationship between the measured parameters and climate. Principal component factor PC1 proved to be related to parameters of EW and the climatic variables of winter-spring; PC2 to parameters of LW and climatic variables of summer–autumn; PC3 to conditions during transitions from humid to dry periods. The three PCs vary between sites and are determined by the climatic conditions during their formation. The study demonstrates that wood anatomical features may provide complementary information to that contained in tree-ring widths. Since such results are obtained on contrasting sites, it is likely that it may be generalized over the wide range of P. halepensis distribution representing a useful proxy for studies on a regional scale.
    Subject(s): Life Sciences ; Plant Pathology ; Tree rings ; Plant Anatomy/Development ; Mediterranean ; Pinus halepensis ; Forestry ; Agriculture ; Plant Physiology ; Intra-annual density fluctuations ; Anatomical characteristics ; Plant Sciences ; Analysis ; Environmental quality
    ISSN: 0931-1890
    E-ISSN: 1432-2285
    Source: Alma/SFX Local Collection
    Source: ProQuest Central
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  • 10
    Language: English
    In: Climate of the past, 2019-09-02, Vol.15 (5), p.1647-1664
    Description: In the northeast of the Iberian Peninsula, few studies have reconstructed drought occurrence and variability for the pre-instrumental period using documentary evidence and natural proxies. In this study, we compiled a unique dataset of rogation ceremonies – religious acts asking God for rain – from 13 cities in the northeast of Spain and investigated the annual drought variability from 1650 to 1899 CE. Three regionally different coherent areas (Mediterranean, Ebro Valley, and Mountain) were detected. Both the Barcelona and the regional Mediterranean drought indices were compared with the instrumental series of Barcelona for the overlapping period (1787–1899), where we discovered a highly significant and stable correlation with the Standardized Precipitation Index of May with a 4-month lag (r=-0.46 and r=-0.53; p〈0.001, respectively). We found common periods with prolonged droughts (during the mid and late 18th century) and extreme drought years (1775, 1798, 1753, 1691, and 1817) associated with more atmospheric blocking situations. A superposed epoch analysis (SEA) was performed showing a significant decrease in drought events 1 year after the volcanic events, which might be explained by the decrease in evapotranspiration due to reduction in surface temperatures and, consequently, the higher availability of water that increases soil moisture. In addition, we discovered a common and significant drought response in the three regional drought indices 2 years after the Tambora volcanic eruption. Our study suggests that documented information on rogation ceremonies contains important independent evidence to reconstruct extreme drought events in areas and periods for which instrumental information and other proxies are scarce. However, drought index for the mountainous areas (denoted Mountain later in the text) presents various limitations and its interpretation must be treated with caution.
    ISSN: 1814-9332
    ISSN: 1814-9324
    E-ISSN: 1814-9332
    Source: Directory of Open Access Journals
    Source: Alma/SFX Local Collection
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