•We studied fourteen variables about reforestation in Spain from 1879 to 2006.•We related the variables with the ecological, political and socieconomic context.•More than five million hectares were ...reforested.•Three different stages explain the process and its landscape-level impact.•The species used changed in every period, native pines were the most used.
Spain had not more than six million hectares of woodlands in the mid-19th century. Nowadays woodlands cover more than sixteen million hectares. During the last one hundred and fifty years, much effort was devoted to improving forest cover and, as a result, five million hectares were artificially regenerated, which represents ten percent of the whole country area. All this work required large nursery infrastructures, thousands of workers and high public investments. The outcome of these reforestation and afforestation efforts is nowadays obvious throughout the Spanish landscapes, and sometimes has given rise to controversy between supporters and opponents. Nevertheless, the process that led to the vast reforestation of Spain has not been yet studied in depth from a historical perspective. This study aims at reconstructing that historical process, by describing it through several features that help to understand the historical development of the artificial forest regeneration policy in Spain, together with its social, political and economic context. The study period comprises since 1879 to present, with special focus on the recent history, that is, since the mid-20th century. The lessons learnt from this analysis may contribute to improving the design of large-scale reforestation policies as well as their potential impacts in other parts of the world and, in the end, shed light on the debate about the possible solutions to deforestation and forest degradation.
Submediterranean forests are considered an ecotone between Mediterranean and Eurosiberian ecosystems, and are very sensitive to global change. A decline of Scots pine (Pinus sylvestris L.) and a ...related expansion of oak species (Quercus spp.) have been reported in the Spanish Pre-Pyrenees. Although this has been associated with increasing drought stress, the underlying mechanisms are not fully understood, and suitable monitoring protocols are lacking. The aim of this study is to bring insight into the physiological mechanisms anticipating selective decline of the pines, with particular focus on carbon and water relations. For this purpose, we performed a sampling campaign covering two growing seasons in a mixed stand of P. sylvestris and Quercus subpyrenaica E.H del Villar. We sampled seasonally twig xylem and soil for water isotope composition (δ18O and δ2H), leaves for carbon isotope composition (δ13C) and stems to quantify non-structural carbohydrates (NSC) concentration, and measured water potential and leaf gas exchange. The first summer drought was severe for both species, reaching low predawn water potential (-2.2 MPa), very low stomatal conductance (12 ± 1.0 mmol m-2 s-1) and near-zero or even negative net photosynthesis, particularly in P. sylvestris (-0.6 ± 0.34 μmol m-2 s-1 in oaks, -1.3 ± 0.16 μmol m-2 s-1 in pines). Hence, the tighter stomatal control and more isohydric strategy of P. sylvestris resulted in larger limitations on carbon assimilation, and this was also reflected in carbon storage, showing twofold larger total NSC concentration in oaks than in pines (7.8 ± 2.4% and 4.0 ± 1.3%, respectively). We observed a faster recovery of predawn water potential after summer drought in Q. subpyrenaica than in P. sylvestris (-0.8 MPa and -1.1 MPa, respectively). As supported by the isotopic data, this was probably associated with a deeper and more reliable water supply in Q. subpyrenaica. In line with these short-term observations, we found a more pronounced negative effect of steadily increasing drought stress on long-term growth in pines compared with oaks. All these observations confer evidence of early warning of P. sylvestris decline and indicate the adaptive advantage of Q. subpyrenaica in the area.
•The masting habit and growth of stone pine were studied for individuals and stands.•A higher regional synchrony of ring-with compared with that of cone yield was found.•Large cone yields did not ...penalise growth during the year of main cone growth.•High positive correlations between growth and cone yield were found lagged 3 years.•Support is given for weather cueing as main masting mechanism of this species.
Trade-offs between life-history traits are common in plants, and those involving growth and reproduction may be evident during mast years. The nutlike seeds of the stone pine (Pinus pinea L.) stand out among the most appreciated Mediterranean forest products, but its lengthy reproductive cycle makes the identification of masting mechanisms challenging. In the Spanish Northern Plateau, stone pine woodlands are managed as multifunctional forests. Here, we investigated whether timber and nut production are compatible goals in the region. Temporal ring-width and cone yield patterns were characterised in five monospecific stands since 1960. At tree level, we found an equivalent allocation of resources to reproductive and non-reproductive (aboveground) biomass for an average year, but harvest index exceeded 80% during mast years. These large yields, however, did not impose a penalty on aboveground biomass increment. Regionally, we reported a slightly larger magnitude of high-frequency synchronous growth (â = 0.50) compared with that of reproduction (â = 0.42), which is important to contextualise the ecological and economical relevance of masting for the species. By investigating growth-yield interannual dynamics, we found that both traits were strongly and positively correlated, although with a 3-year lag. Therefore, years favouring a high growth coincided with large conelet emergences leading to abundant seed rains to occur three years later, which pointed to key environmental drivers common to both traits. Actually, radial growth and reproduction partly responded to the same climate factors, with climate three years before seed rain being related to masting in a similar way as it was related to ring-width of this same year. Our results provide evidence for the proposed link between masting and growth, and suggest that resources are not diverted from growth during cone filling in stone pine. We conclude that timber production and nut production are perfectly compatible in this species.
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.
Abstract
Drought is projected to occur more frequently and intensely in the coming decades, and the extent to which it will affect forest functioning will depend on species-specific responses to ...water stress. Aiming to understand the hydraulic traits and water dynamics behind water-saver and water-spender strategies in response to drought and recovery, we conducted a pot experiment with two species with contrasting physiological strategies, Scots pine (Pinus sylvestris L.) and Portuguese oak (Quercus faginea L.). We applied two cycles of soil drying and recovery and irrigated with isotopically different water to track fast changes in soil and stem water pools, while continuously measuring physiological status and xylem water content from twigs. Our results provide evidence for a tight link between the leaf-level response and the water uptake and storage patterns in the stem. The water-saver strategy of pines prevented stem dehydration by rapidly closing stomata which limited their water uptake during the early stages of drought and recovery. Conversely, oaks showed a less conservative strategy, maintaining transpiration and physiological activity under dry soil conditions, and consequently becoming more dehydrated at the stem level. We interpreted this dehydration as the release of water from elastic storage tissues as no major loss of hydraulic conductance occurred for this species. After soil rewetting, pines recovered pre-drought leaf water potential rapidly, but it took longer to replace the water from conductive tissues (slower labeling speed). In contrast, water-spender oaks were able to quickly replace xylem water during recovery (fast labeling speed), but it took longer to refill stem storage tissues, and hence to recover pre-drought leaf water potential. These different patterns in sap flow rates, speed and duration of the labeling reflected a combination of water-use and storage traits, linked to the leaf-level strategies in response to drought and recovery.
Whole-stand models normally require data on initial stand basal area and dominant height. Dominant height measurements are time-consuming and often imprecise, compromising subsequent predictions. ...Poplar plantations provide a special case where basal area correlates with site index; a whole-stand model could thus be based on stand basal area. We report a static model constructed by the generalized algebraic difference approach (GADA) for poplar plantations for three different hybrid poplars (
Populus
×
euramericana (Dode) Guinier “I-214”, “MC”, and “Luisa Avanzo”) in northeast Spain. The transition function was based on current stand basal area and was fitted with data from 158 permanent plots ranging from 1- to 17-year-old plantations. Merchantable stand volume was estimated by a volume equation where height was predicted by a height–basal area relationship based on 458 temporary plots. The model differences between clones were compared using the nonlinear extra sum of squares method. Significant differences were detected, while Luisa Avanzo presented the highest merchantable volume at the end of the rotation. Errors in basal area predictions were below 20% within 6 years in the case of Luisa Avanzo and MC clones, and within 3 years in the case of I-214. Our research showed that satisfactory predictions can be obtained using GADA with a single transition function based on an easily measurable variable such as stand basal area.
Desde que iniciase su andadura como profesión en España, ha quedado constancia del compromiso ético de las y los profesionales del Trabajo Social en las respuestas que han venido ofreciendo en cada ...época a los conflictos y dilemas éticos que se originaban en el ejercicio profesional. Ante la ausencia de estudios de similares características a nivel nacional, el objetivo del presente artículo consiste en explicar nuestra propuesta de periodización de la evolución del compromiso ético de las y los profesionales del Trabajo Social en España a partir del estudio de los valores éticos que han sido destacados por las y los mismos desde 1861 hasta la actualidad. Para ello, explicaremos los diferentes períodos en los que hemos estructurado la evolución de la Ética del Trabajo Social en España, identificando algunos elementos del estoicismo.
El objetivo del artículo es definir y explicar los tipos de profesionales del Trabajo Social existentes en España mediante una investigación descriptiva, cuantitativa y tipológica. Esta primera ...aproximación puede servir para iniciar la reflexión sobre la organización profesional del Trabajo Social en España y para identificar las características que definen su labor profesional. Los resultados muestran la existencia de doce tipos de profesionales del Trabajo Social en España.
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