BUSCADOR RECOLECTA

Forest thinning can significantly affect hydrological processes. However, these effects largely vary with forest
types, climate, thinning intensity, and hydrological variables of interest. Understanding these effects and their
variations can significantly support thinning treatments’ design and selection to ensure desired hydrological
benefits. In this global-level review paper, we report the first comprehensive meta-analysis on the effects of
thinning on major hydrological processes with an emphasis on rainfall partitioning, soil moisture and evapotranspiration processes. The synthesized and reviewed studies encompass different biophysical conditions
(climate and forest ecosystems), silvicultural systems, and time scales (from weeks to decades) across continents.
The results showed a significant increase in net precipitation, soil moisture and tree-level water use after thinning
(the effect sizes are 1.19, 1.14 and 1.56 relative to the value of the control, respectively), while decreases in
stemflow and transpiration (the effect sizes of 0.42 and 0.6 relative to the value of the control, respectively).
Thinning intensity of about 50% of the stand density is determined as the threshold at or over which hydrological
processes are significantly affected. The duration of thinning effect can be set between 2.6 and 4.3 (throughfall)
and 3.1–8.6 years (soil moisture and transpiration), asking for repeated thinning in order to effectively sustain
these effects. These global averages can serve as benchmarks for assessment and comparisons, but the effects of
thinning depend on local biophysical conditions and thinning treatments. The literature review on the rest of the
studied hydrological variables suggests that thinning generally enhance runoff to increase water yield and
groundwater recharge. Thinning can also have a positive or limited role in water use efficiency (WUE), but it
mitigates the effects of drought through increasing WUE. Moderate adverse effects on water quality can be
prevented by adequate forest managements to prevent soil degradation. Nevertheless, more researches at relatively less studied regions are needed to support a more robust analysis of these reviewed hydrological variables.
The management implications of the synthesized and reviewed results are suggested and discussed within the
context of climate change., Cehyrfo-Med (CGL2017-86839-C3-2-R funded by
MCIN/AEI /10.13039/501100011033/ and FEDER a way to make
Europe), SilvAdapt.net (RED2018-102719-T funded by MCIN/AEI
/10.13039/501100011033), RESILIENT-FORESTS (LIFE17 CCA/ES/
000063), JSPS KAKENHI (JP 18H04152 and JP 19H03088), contract
RE21NOR-029 (British Columbia Ministry of Forests, Lands, Natural
Resource Operations and Rural Development, Canada), and the Canadian NSERC CRD (CRDPJ 485176-15) partly supported this work. Open
access was funded by CRUE-Universitat Politècnica de València.

Proactive silviculture treatments (e.g., thinning) may increase C sequestration contributing to climate change mitigation, although, there are still questions about this effect in Mediterranean pine forests. The aim of this research was to quantify the storage of biomass and soil organic carbon in Pinus forests along a climatic gradient from North to South of the Iberian Peninsula. Nine experimental Pinus spp trials were selected along a latitudinal gradient from the pre-Pyrenees to southern Spain. At each location, a homogeneous area was used as the operational scale, and three thinning intensity treatments: unthinned or control (C), intermediate thinning (LT, removal of 30–40% of the initial basal area) and heavy thinning (HT, removal of 50–60%) were conducted. Growth per unit area (e.g., expressed as basal area increment-BAI), biomass, and Soil Organic Carbon (SOC) were measured as well as three sets of environmental variables (climate, soil water availability and soil chemical and physical characteristics). One-way ANOVA and Structural Equation Modelling (SEM) were used to study the effect of thinning and environmental variables on C sequestration. Biomass and growth per unit area were higher in the control than in the thinning treatments, although differences were only significant for P. halepensis. Radial growth recovered after thinning in all species, but it was faster in the HT treatments. Soil organic carbon (SOC10, 0–10 cm depth) was higher in the HT treatments for P. halepensis and P. sylvestris, but not for P. nigra. SEM showed that Pinus stands of the studied species were beneficed by HT thinning, recovering their growth quickly. The resulting model explained 72% of the variation in SOC10 content, and 89% of the variation in silvicultural condition (basal area and density) after thinning. SOC10 was better related to climate than to silvicultural treatments. On the other hand, soil chemical and physical characteristics did not show significant influence over SOC10- Soil water availability was the latent variable with the highest influence over SOC10. This work is a new contribution that shows the need for forest managers to integrate silviculture and C sequestration in Mediterranean pine plantations, This research was collaborative funded by the following projects: SilvAdapt.net (RED2018-102719-T) funded by MCIN/AEI/10.13039/501100011033, Life-FOREST CO2 (LIFE14 CCM/ES/001271), ALTERACLIM (CGL2015-69773-C2-1-P), IN-ERTIA (PID2019-111332RB-C22-BDV), CEHYRFO-MED (CGL2017-86839-C3-2-R), RESILIENTFORESTS (LIFE17 CCA/ES/000063), TRANSHYMED (CGL2016-75957-R), AGL2017-83828-C2-2-R and ESPAS (CGL2015-65569-R), caRRRascal (RTI2018-095037-B-I00), TIMENUTRIENT (AGL2016-76463-P), and ISO-Pine (UCO-1265298). F.J.R.-G. was supported by a post-doctoral fellowship of the Junta de Andalucía (Spain) and the European Social Fund 2014-2020 Program (DOC_0055). A.J. Molina is beneficiary of an ‘APOSTD’ fellowship (APOSTD/2019/111) funded by the Generalitat Valenciana.

Adaptive forest management (AFM) is an urgent need because of the uncertainty regarding how changes in the climate will affect the structure, composition and function of forests during the next decades. Current research initiatives for the long-term monitoring of impacts of silviculture are scattered and not integrated into research networks, with the consequent losses of opportunities and capacity for action. To increase the scientific and practical impacts of these experiences, it is necessary to establish logical frameworks that harmonize the information and help us to define the most appropriate treatments. In this context, a number of research groups in Spain have produced research achievements and know-how during the last decades that can allow for the improvement in AFM. These groups address the issue of AFM from different fields, such as ecophysiology, ecohydrology and forest ecology, thus resulting in valuable but dispersed expertise. The main objective of this work is to introduce a comprehensive strategy aimed to study the implementation of AFM in Spain. As a first step, a network of 34 experimental sites managed by 14 different research groups is proposed and justified. As a second step, the most important AFM impacts on Mediterranean pines, as one of the most extended natural and planted forest types in Spain, are presented. Finally, open questions dealing with key aspects when attempting to implement an AFM framework are discussed. This study is expected to contribute to better outlining the procedures and steps needed to implement regional frameworks for AFM., A.J. Molina is beneficiary of an “APOSTD” fellowship (APOSTD/2019/111) funded
by the Generalitat Valenciana. M. Moreno-de las Heras is beneficiary of a Serra Hunter fellowship (UB-LE-9055) funded by the Generalitat de Catalunya. F.J. Ruiz-Gómez is supported by a
postdoctoral fellowship of the Junta de Andalucía (Sevilla, Spain), and the European Social Fund
2014–2020 Program (DOC_0055). The authors received national and international funding through
the following projects: SILVADAPT.NET (RED2018-102719-T), ESPECTRAMED (CGL2017-86161-R),
Life-FOREST CO2 (LIFE14 CCM/ES/001271), ALTERACLIM (CGL2015-69773-C2-1-P), INERTIA
(PID2019-111332RB-C22-BDV), CEHYRFO-MED (CGL2017-86839-C3-2-R), DEHESACLIM (IB16185),
RESILIENTFORESTS (LIFE17 CCA/ES/000063), Rhysotto (PID2019-106583RB-I00), AGL2017-83828-
C2-2-R, RTI2018-096884-B-C31, ESPAS (CGL2015-65569-R), and caRRRascal (RTI2018-095037-B-I00).

[EN] Having regard to the substantial world-scale forest restoration needs, the efforts must be done efficiently, which necessarily forces to consider the adaptation of new forests to the extremes arising from climate change. In this context, species selection strategies should enhance long-term functional resilience in the face of novel environmental scenarios. The use of plant functional traits for selecting species under climate change might be advantageous over more traditional taxon-based criteria as an adaptive forestry management strategy. In this work, we studied which functional traits (across species) have played a relevant role on field performance and fitness in a mull-species reforestation trial in a Mediterranean dryland affected by an extreme drought event. Different traits both from the individual plant and from the species were studied in seven species both at the short and the mid-term (10 years). The relative importance (RI) or contribution of the different traits to plantation performance was assessed through boosted regression tree models. The results showed that, under favorable climatic conditions, mean survival was above 70% and individual plant functional traits held up to 60% of importance on such value. The impact of species functional traits was low in this case (less than 18%) pointing out that all the species were performing within their niche at this point. However, after the driest year on record, the role of the latter on survival rose up to 53% of RI and survival sharply decreased to 33%, with some species showing negligible survival rate (< 10%). The dynamic response of stomata and xylem resistance to cavitation, together with roofing depth, were the main traits (species traits) identified in successful performance facing the extreme environmental factors. Thus, trait-oriented approach to select species represent a key tool in the implementation of new and successful forest restoration strategies to design resistant and resilient ecosystems adapted to the climate change challenges., This study is part of two research projects: "Comprehensive quality control of the reforestation works in the public forests of Cortes de Pallas, Valencia" signed between the Polytechnic University of Valencia (Re-ForeST) and the state-owned company TRAGSA, and "Monitoring and evaluation of the reforestation in the forest V-143 Muela de Cortes, in the municipality of Cortes de Pallas (Valencia), 10 years after its execution" (contract number CNMY18/0301/26), signed between the Polytechnic University of Valencia (Re-ForeST) and Valencia Regional Government (CMAAUV, Generalitat Valenciana) The authors are grateful to CYGSA staff (Maria Amparo Barber and Hector Cantos), Tragsa (Juan Ramon Torres), Vaersa (Pedro Lazaro) and Ana Isabel Aparicio (UPV) for their assistance in the fieldwork during the installation of the plot and early growth measurements. Projects CEHYRFO-MED (CGL2017-86839-C3-2-R), RESILIENT-FORESTS (LIFE17 CCA/ES/000063) and SilvAdapt.net (RED2018-102719-T) are acknowledged.

[EN] Forest thinning can significantly affect hydrological processes. However, these effects largely vary with forest types, climate, thinning intensity, and hydrological variables of interest. Understanding these effects and their variations can significantly support thinning treatments' design and selection to ensure desired hydrological benefits. In this global-level review paper, we report the first comprehensive meta-analysis on the effects of thinning on major hydrological processes with an emphasis on rainfall partitioning, soil moisture and evapotranspiration processes. The synthesized and reviewed studies encompass different biophysical conditions (climate and forest ecosystems), silvicultural systems, and time scales (from weeks to decades) across continents. The results showed a significant increase in net precipitation, soil moisture and tree-level water use after thinning (the effect sizes are 1.19, 1.14 and 1.56 relative to the value of the control, respectively), while decreases in stemflow and transpiration (the effect sizes of 0.42 and 0.6 relative to the value of the control, respectively). Thinning intensity of about 50% of the stand density is determined as the threshold at or over which hydrological processes are significantly affected. The duration of thinning effect can be set between 2.6 and 4.3 (throughfall) and 3.1-8.6 years (soil moisture and transpiration), asking for repeated thinning in order to effectively sustain these effects. These global averages can serve as benchmarks for assessment and comparisons, but the effects of thinning depend on local biophysical conditions and thinning treatments. The literature review on the rest of the studied hydrological variables suggests that thinning generally enhance runoff to increase water yield and groundwater recharge. Thinning can also have a positive or limited role in water use efficiency (WUE), but it mitigates the effects of drought through increasing WUE. Moderate adverse effects on water quality can be prevented by adequate forest managements to prevent soil degradation. Nevertheless, more researches at relatively less studied regions are needed to support a more robust analysis of these reviewed hydrological variables. The management implications of the synthesized and reviewed results are suggested and discussed within the context of climate change., The authors are grateful to Javier Perez Romero (UPV, Spain), Risa Kamitani (KUF, Japan), and Yuzhu Li (KUF, Japan) for their assistance in this work. Projects: Cehyrfo-Med (CGL2017-86839-C3-2-R funded by MCIN/AEI /10.13039/501100011033/ and FEDER a way to make Europe), SilvAdapt.net (RED2018-102719-T funded by MCIN/AEI /10.13039/501100011033), RESILIENT-FORESTS (LIFE17 CCA/ES/ 000063), JSPS KAKENHI (JP 18H04152 and JP 19H03088), contract RE21NOR-029 (British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development, Canada), and the Canadian NSERC CRD (CRDPJ 485176-15) partly supported this work. Open access was funded by CRUE-Universitat Politecnica de Valencia

[EN] Water is the key element that modulates the provision of goods and services together with global/climate
stressors affecting semiarid forests. In this sense, there is a need to improve the understanding and quantification
of forest and water relationships as affected by forest management. This work addresses this issue by comparing
net rainfall (Pn) redistribution into different belowground hydrological processes (BHP) in two forest types after
a thinning treatment: a holm oak coppice (HU) and a post-fire Aleppo pine regeneration (CAL). The relative
contribution (RI) of forest structure, antecedent soil moisture (¿st), rainfall and meteorological conditions on the
BHP was assessed through boosted regression trees models. In both sites, the RI of the forest structure itself was
limited (< 10%). However, ¿st, which clearly increased significantly with thinning, received an average RI of
29%. Surface and subsurface lateral flows showed values<1% of gross rainfall (Pg) in either site and were not
significantly affected by thinning. On the other hand, soil moisture and drainage were affected by the thinning
treatment, although with different extent depending on the site: in the drier site (CAL), the increased Pn in the
thinning was mainly allocated into increased soil water content, with very limited improvement in drainage
(< 10 mm/year); in contrast, in the wetter continental site of HU, drainage to deeper soil layers was the most
remarkable effect of thinning (50 mm/year higher than in control), given the higher ¿st and hence the lower soil
water storage available. Thinning also improved the response of BHP during drought, making these processes
more elastic and less vulnerable to climatic extremes. The results presented here complement those previously
reported on rainfall partitioning in these sites and all together provide a comprehensive understanding of the
short-term effect (3¿4 years) of water-oriented silviculture in Quercus ilex and Pinus halepensis low-biomass
semiarid forests. Questions such as the long-term effects of thinning remain open for these ecosystems., This study is a component of research projects: HYDROSIL (CGL2011-28776-C02-02), SILWAMED (CGL2014-58127-C3-2), CEHYRFO-MED (CGL2017-86839-C3-2-R) funded by the Spanish Ministry of Science and Innovation (Spain), FEDER funds (EU) and LIFE17 CCA/ES/000063 RESILIENTFORESTS. The authors are grateful to the Valencia Regional Government (CMAAUV), VAERSA, ACCIONA, the "Sierra Calderona" Natural Park and the communal authority of Serra, for their support in allowing the use of the experimental forest and for their assistance in carrying out the fieldwork. A.J. Molina is beneficiary of a "Juan de la Cierva" post-doctoral fellowship funded by the Spanish Ministry of Economy and Competitiveness.

[EN] In order to quantify the impacts of silvicultural treatments in semiarid forests, it is necessary to know how they affect key aboveground processes and also properties characterizing the forest floor and mineral soil compartments. The general objective of this work is to study the mid-term effects of thinning intensity on forest floor and soil properties after 13 years following the intervention. The experimental design consisted of a randomized block design with four thinning treatments (3 thinning intensity plots plus a control or unmanaged plot) and three blocks or replicates. Several determinations, such as total organic carbon, dissolved organic carbon, or basal respiration, were performed for characterizing forest floor and mineral soil by considering three random sampling points per experimental plot. Thirteen years after thinning, total organic content, the different organic carbon fractions studied, and basal respiration were higher in the forest floor of the unmanaged plot. These results, however, were contrasted to those obtained for the mineral soil, where significant differences between the treatments were only observed in basal respiration and C/N ratio, while the different organic carbon fractions were not affected by thinning intensity. Our results suggest better soil quality where biological activity is enhanced as a consequence of improved environmental conditions and also litterfall input. The latter is especially important in forests with tree leaves of low biodegradability, where new understorey species promoted by thinning can provide higher nutrient availability for the remaining trees and, therefore, better forest resilience., A.J. Molina is the beneficiary of an "APOSTD' fellowship (APOSTD/2019/111) funded by the Generalitat Valenciana. The authors received national and international funding through the following projects: SILVADAPT.NET (RED2018-102719-T funded by MCIN/AEI/10.13039/501100011033), CEHYRFO-MED (CGL2017-86839-C3-2-R funded by MCIN/AEI/10.13039/501100011033 and FEDER a way to make Europe), and RESILIENTFORESTS (LIFE17 CCA/ES/000063)

[EN] Poor reforestation outcomes imply unfulfillment of program goals and might erode institutional willpower and political momentum towards reforestation efforts, affecting both public and private support. However, program improvement in real reforestation projects is challenging due to the conjunction of many different variables of distinct nature that mutually interact and feedback in an inextricable fashion. In this work, we deploy a comprehensive integral assessment of reforestation program based in a study case where technical and environmental information is gathered and related to indicators of performance both in the short and mid-term. This assessment aims to provide reliable end-results for survival and growth, unveils pitfalls on successful plantation establishment and allows for learning processes on how to improve plantation performance and the potential margin for this improvement. The selected project was carried out on harsh site conditions, with different species, cultural treatments and contractors, and was affected by the driest year on record, encompassing enough technical and ecological complexity that makes it suitable for the purpose of this study. Mortality, either in the short (53%) or in the mid-term (83%), was high, but very variable according to site and species. Anthropogenic variables (project planning and execution) gathered high relative importance on plantation performance in the first two years (11-29%) that decreased with time, whilst environmental variables (site and meteorological) showed increased importance ten years after planting (>50%). In the short-term, soil moisture and meteorology during planting season have been identified as key factors that trigger the effects of both technical decisions (planting date and planting technique) and other environmental variables on performance. In the design phase, some decisions related to zoning, species selection and cultural treatments application have been related to poor performance. The results provide practical information and guidelines for forest restoration improvement under similar setup., This study is part of two research projects: "Comprehensive quality control of the reforestation works in the public forests of Cortes de Pallas, Valencia", signed by both the Polytechnic University of Valencia (Re-ForeST) and the state-owned company TRAGSA; and "Monitoring and evaluation of reforestation in forest V-143 Muela de Cortes, in the municipality of Cortes de Pallas (Valencia) , 10 years after its execution" (contract number CNMY18/0301/26) , signed by both the Polytechnic University of Valencia (Re-ForeST) and the Regional Government (CMAAUV, Generalitat Valenciana) . The authors are grateful to CYGSA staff (M Amparo Barber and Hector Cantos) , TRAGSA (Juan Ramon Torres) , Vaersa (Pedro Lazaro) and Ana Isabel Aparicio (UPV) for their assistance in the fieldwork during the installation of the plots and early growth measurements. Projects CEHYRFO-MED (CGL2017-86839-C3-2-R) , RESILIENT-FORESTS (LIFE17 CCA/ES/000063) and SilvAdapt.net (RED2018-102719-T) are acknowledged.

[EN] Proactive silviculture treatments (e.g., thinning) may increase C sequestration contributing to climate change mitigation, although, there are still questions about this effect in Mediterranean pine forests. The aim of this research was to quantify the storage of biomass and soil organic carbon in Pinus forests along a climatic gradient from North to South of the Iberian Peninsula. Nine experimental Pinus spp trials were selected along a latitudinal gradient from the pre-Pyrenees to southern Spain. At each location, a homogeneous area was used as the operational scale, and three thinning intensity treatments: unthinned or control (C), intermediate thinning (LT, removal of 30-40% of the initial basal area) and heavy thinning (HT, removal of 50-60%) were conducted. Growth per unit area (e.g., expressed as basal area increment-BAI), biomass, and Soil Organic Carbon (SOC) were measured as well as three sets of environmental variables (climate, soil water availability and soil chemical and physical characteristics). One-way ANOVA and Structural Equation Modelling (SEM) were used to study the effect of thinning and environmental variables on C sequestration. Biomass and growth per unit area were higher in the control than in the thinning treatments, although differences were only significant for P. halepensis. Radial growth recovered after thinning in all species, but it was faster in the HT treatments. Soil organic carbon (SOC10, 0-10 cm depth) was higher in the HT treatments for P. halepensis and P. sylvestris, but not for P. nigra. SEM showed that Pinus stands of the studied species were beneficed by HT thinning, recovering their growth quickly. The resulting model explained 72% of the variation in SOC10 content, and 89% of the variation in silvicultural condition (basal area and density) after thinning. SOC10 was better related to climate than to silvicultural treatments. On the other hand, soil chemical and physical characteristics did not show significant influence over SOC10- Soil water availability was the latent variable with the highest influence over SOC10. This work is a new contribution that shows the need for forest managers to integrate silviculture and C sequestration in Mediterranean pine plantations., This research was collaborative funded by the following projects: SilvAdapt.net (RED2018-102719-T) funded by MCIN/AEI/10.13039/501100011033, Life-FOREST CO2 (LIFE14 CCM/ES/001271), ALTERACLIM (CGL2015-69773-C2-1-P), IN-ERTIA (PID2019-111332RB-C22-BDV), CEHYRFO-MED (CGL2017-86839-C3-2-R), RESILIENTFORESTS (LIFE17 CCA/ES/000063), TRANSHYMED (CGL2016-75957-R), AGL2017-83828-C2-2-R and ESPAS (CGL2015-65569-R), caRRRascal (RTI2018-095037-B-I00), TIMENUTRIENT (AGL2016-76463-P), and ISO-Pine (UCO-1265298). F.J.R.-G. was supported by a post-doctoral fellowship of the Junta de Andalucia (Spain) and the European Social Fund 2014-2020 Program (DOC_0055). A.J. Molina is beneficiary of an "APOSTD" fellowship (APOSTD/2019/111) funded by the Generalitat Valenciana. The information included reflects only the opinion of the authors and the European Commission/Agency is not responsible for any use that may be made of the information contained in this scientific paper.

[EN] Hydrology-oriented forest management sets water as key factor of the forest management for adaptation due to water is the most limiting factor in the Mediterranean forest ecosystems. The aim of this study was to apply Bayesian Network modeling to assess potential indirect effects and trade-offs when hydrology-oriented forest management is applied to a real Mediterranean forest ecosystem. Water, carbon and nitrogen cycles, and forest fire risk were included in the modeling framework. Field data from experimental plots were employed to calibrate and validate the mechanistic Biome-BGCMuSo model that simulates the storage and flux of water, carbon, and nitrogen between the ecosystem and the atmosphere. Many other 50-year long scenarios with different conditions to the ones measured in the field experiment were simulated and the outcomes employed to build the Bayesian Network in a linked chain of models. Hydrology-oriented forest management was very positive insofar as more water was made available to the stand because of an interception reduction. This resource was made available to the stand, which increased the evapotranspiration and its components, the soil water content and a slightly increase of deep percolation. Conversely, Stemflow was drastically reduced. No effect was observed on Runof due to the thinning treatment. The soil organic carbon content was also increased which in turn caused a greater respiration. The long-term effect of the thinning treatment on the LAI was very positive. This was undoubtedly due to the increased vigor generated by the greater availability of water and nutrients for the stand and the reduction of competence between trees. This greater activity resulted in an increase in GPP and vegetation carbon, and therefore, we would expect a higher carbon sequestration. It is worth emphasizing that this extra amount of water and nutrients was taken up by the stand and did not entail any loss of nutrients., This study is a component of research projects: HYDROSIL (CGL2011-28776-C02-02), SILWAMED (CGL2014-58127-C3-2) and CEHYRFO-MED (CGL2017-86839-C3-2-R) funded by the Spanish Ministry of Science and Innovation and FEDER funds. The authors are grateful to the Valencia Regional Government (CMAAUV, Generalitat Valenciana), ACCIONA for their support in allowing the use of the experimental forest and for their assistance in carrying out the fieldwork.

[EN] Semi-arid forests are water limited environments considered as low-productive. As a result, these forests usually end up unmanaged and abandoned, with the subsequent wild fire risk increasing, water yield decreasing and a general diminishing of the forest resilience. Hydrological-oriented silviculture could be a useful alternative that increases management possibilities by combining forest productivity and water yield. However, the slight water yield increase after forest management together with the low forest productivity, could make this option insufficient for semi-arid forests, and other goods and services should be included and quantified. In this sense, the present study analyzes to what extent semi-arid forest management for water yield results effective and profitable at catchment scale, and how does it improve when it is combined with other benefits such as biomass production and fire risk diminishing. To that end, the effects of forest management of semi-arid Aleppo pine post-fire regeneration stands are analyzed in terms of water yield (TETIS-VEG model), fire risk (KDBY index and FARSITE) and biomass production, at catchment scale. Regarding to water yield, the results confirmed the slight effect of forest management on its increase (average increase of 0.27 +/- 0.29 mm yr(-1)), at the same time that highlighted the role of the upper catchment area as an important water contributor. The management produced 4161.6 Mg of biomass, and decreased in 27 +/- 17% and 25.6 +/- 14.1% the fire risk and fire propagation, respectively. Finally, a simple economic estimation of the management profitability is carried out by means of comparing the Benefit/Cost ratio of the managed and unmanaged scenarios. Both scenarios were always above the unity when just considering water as benefit, although the unmanaged scenario produced a higher ratio, as no management costs are expended. Contrarily, when wildfire was also included into the evaluation, the situation is overturned for wildfires equal or higher than 1.5 day duration, where the forest management is shown as the most convenient alternative., This study is a component of the research projects: INTEGRA (CGL2011-28776-0O2), E-HIDROMED (CGL2014-58127-C3) and CEHYRFO-MED (CGL2017-86839-C3-2-R) funded by the Spanish Ministry of Science and Innovation and FEDER funds, and LIFE17 CCA/ES/000063 RESILIENTFORESTS. The authors are grateful to the Valencia Regional Government (CMAAUV, Generalitat Valenciana), the VAERSA staff, the Natural Park staff and the communal authority of Serra (specially Juanjo Mayans) for their support and allowing the use of the Natural Park experimental forest.

[EN] The effects of a thinning treatment on soil respiration (Rs) were analysed in two dryland forest types with a Mediterranean climate in east Spain: a dry subhumid holm oak forest (Quercus ilex subsp. ballota) in La Hunde (HU); a semiarid postfire regenerated Aleppo pine (Pinus halepensis) forest in Sierra Calderona (CA). Two twin plots were established at each site: one was thinned (T) and the other was the control (C). Rs, soil humidity and temperature were measured regularly in the field at nine points per plot distributed into three blocks along the slope for 3 years at HU and for 2 years at CA after forest treatment. Soil heterotrophic activity was measured in laboratory on soil samples obtained bimonthly from December 2012 to June 2013 at the HU site. Seasonal Rs distribution gave low values in winter, began to increase in spring before lowering as soil dried in summer. This scenario indicates that with a semiarid climate, soil respiration is controlled by both soil humidity and soil temperature. Throughout the study period, the mean Rs value in the HU C plot was 13% higher than at HU T, and was 26% higher at CA C than the corresponding CA T plot value, being the differences significantly higher in control plots during active growing periods. Soil microclimatic variables explain the biggest proportion of variability for Rs: soil temperature explained 24.1% of total variability for Rs in the dry subhumid forest; soil humidity accounted for 24.6% of total variability for Rs in the semiarid forest. As Mediterranean climates are characterised by wide interannual variability, Rs showed considerable variability over the years, which can mask the effect caused by thinning treatment., This study was supported by research projects Hydrological characterisation of forest structures on a plot scale for adaptive management (CGL2011-28776-C02-02) and SILWAMED (CGL2014-58127-C3-2) funded by the Spanish Ministry of Science and Innovation and FEDER funds. CEHYRFO-MED (CGL201786839-C3-2-R), RESILIENT-FORESTS (LIFE17 CCA/ES/000063) and SilvAdapt. net (RED2018-102719-T) are also acknowledged. The authors are grateful to the Valencia Regional Government, VAERSA, ACCIONA and the "Sierra Calderona" Natural Park for their support in allowing us to use experimental forests and for their assistance in fieldwork. We also thank Rafael Herrera from the Centro de Ecologia, Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela, and the anonymous reviewers for critically reviewing the manuscript.

[EN] Climate change increases the occurrence and severity of droughts due to increasing temperatures, altered circulation patterns, and reduced snow occurrence. While Europe has suffered from drought events in the last decade unlike ever seen since the beginning of weather recordings, harmonized long-term datasets across the continent are needed to monitor change and support predictions. Here we present soil moisture data from 66 cosmic-ray neutron sensors (CRNSs) in Europe (COSMOS-Europe for short) covering recent drought events. The CRNS sites are distributed across Europe and cover all major land use types and climate zones in Europe. The raw neutron count data from the CRNS stations were provided by 24 research institutions and processed using state-of-the-art methods. The harmonized processing included correction of the raw neutron counts and a harmonized methodology for the conversion into soil moisture based on available in situ information. In addition, the uncertainty estimate is provided with the dataset, information that is particularly useful for remote sensing and modeling applications. This paper presents the current spatiotemporal coverage of CRNS stations in Europe and describes the protocols for data processing from raw measurements to consistent soil moisture products. The data of the presented COSMOS-Europe network open up a manifold of potential applications for environmental research, such as remote sensing data validation, trend analysis, or model assimilation The dataset could be of particular importance for the analysis of extreme climatic events at the continental scale. Due its timely relevance in the scope of climate change in the recent years, we demonstrate this potential application with a brief analysis on the spatiotemporal soil moisture variability. The dataset, entitled "Dataset of COSMOS-Europe: A European network of Cosmic-Ray Neutron Soil Moisture Sensors", is shared via Forschungszentrum Julich: https://doi.org/10.34731/x9s3-kr48 (Bogena and Ney, 2021)., We thank TERENO (Terrestrial Environmental Observatories), funded by the Helmholtz-Gemeinschaft for the financing and maintenance of CRNS stations. We acknowledge financial support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) of the research unit FOR 2694 Cosmic Sense (grant no. 357874777) and by the German Federal Ministry of Education of the Research BiookonomieREVIER, Digitales Geosystem -Rheinisches Revier project (grant no. 031B0918A). COSMOS-UK has been supported financially by the UK's Natural Environment Research Council (grant no. NE/R016429/1). The Olocau experimental watershed is partially supported by the Spanish Ministry of Science and Innovation through the research project TETISCHANGE (grant no. RTI2018-093717-BI00). The Calderona experimental site is partially supported by the Spanish Ministry of Science and Innovation through the research projects CEHYRFO-MED (grant no. CGL2017-86839C3-2-R) and SILVADAPT.NET (grant no. RED2018-102719-T) and the LIFE project RESILIENT FORESTS (grant no. LIFE17 CCA/ES/000063). The University of Bristol's Sheepdrove sites have been supported by the UK's Natural Environment Research Council through a number of projects (grant nos. NE/M003086/1, NE/R004897/1, and NE/T005645/1) and by the International Atomic Energy Agency of the United Nations (grant no. CRP D12014).

[EN] Marginal semi-arid forests in areas currently affected by climate change are a challenge to forest management, which has to focus on key functional traits that can effectively contribute to resistance under extreme drought. We studied the effects of thinning in a marginal forest by quantifying functional responses relating to growth, carbon and water fluxes. Two experimental plots were established, one thinned in 2012 and the other one left as a control. The environmental conditions varied substantially during the 4-year study period, although dry years predominated. There were signs of dieback in the control with a decreasing inter-annual trend in LAI, as opposed to the treated plots, where LAI by the end of the study almost reached pre-thinning levels. Sap flow and transpiration were greatly enhanced by the treatment, with thinned trees transpiring 22.41 tree(-1) day(-1) in the growing season, about twice the control figures. The seasonal patterns of transpiration and soil moisture were uncoupled, indicating a contribution of deep groundwater to the former flux. In the control, limitations to water and carbon dynamics (canopy conductance) occurred at soil moisture values below 16%, whereas in the thinned trees these limitations appeared when soil moisture dropped below 10%. Overall, oaks' transpiration was enhanced with thinning to the point that stand-water use surpassed that of the control by the second half of the study period, averaging 24% of gross rainfall in both plots. Soil evaporation increased from 12 to 20% of gross rainfall after treatment in the overall period. The treatment had a profound watering effect in this marginal forest, led by fewer trees using the same amount of water as those in the untreated overstocked plot. This research may provide guidelines for ecohydrology-oriented silviculture in stands experiencing tree encroachment and transformation into shrublands that are more prone to global change-induced disturbances., This study is a component of the research projects HYDROSIL (CGL2011-28776-C02-02), SILWAMED (CGL2014-58127-C3-2) and CEHYRFO-MED (CGL2017-86839-C3-2-R), funded by the Spanish Ministry of Science and Innovation and the FEDER fund of the EU. The authors are grateful to the Valencia Regional Government (CMAAUV, Generalitat Valenciana) and ACCIONA for their support in allowing the use of the experimental forest La Hunde and for their assistance in the fieldwork.

[EN] Adaptive forest management (AFM) is an urgent need because of the uncertainty regarding how changes in the climate will affect the structure, composition and function of forests during the next decades. Current research initiatives for the long-term monitoring of impacts of silviculture are scattered and not integrated into research networks, with the consequent losses of opportunities and capacity for action. To increase the scientific and practical impacts of these experiences, it is necessary to establish logical frameworks that harmonize the information and help us to define the most appropriate treatments. In this context, a number of research groups in Spain have produced research achievements and know-how during the last decades that can allow for the improvement in AFM. These groups address the issue of AFM from different fields, such as ecophysiology, ecohydrology and forest ecology, thus resulting in valuable but dispersed expertise. The main objective of this work is to introduce a comprehensive strategy aimed to study the implementation of AFM in Spain. As a first step, a network of 34 experimental sites managed by 14 different research groups is proposed and justified. As a second step, the most important AFM impacts on Mediterranean pines, as one of the most extended natural and planted forest types in Spain, are presented. Finally, open questions dealing with key aspects when attempting to implement an AFM framework are discussed. This study is expected to contribute to better outlining the procedures and steps needed to implement regional frameworks for AFM., A.J. Molina is beneficiary of an "APOSTD" fellowship (APOSTD/2019/111) funded by the Generalitat Valenciana. M. Moreno-de las Heras is beneficiary of a Serra Hunter fellowship (UB-LE-9055) funded by the Generalitat de Catalunya. F.J. Ruiz-Gomez is supported by a postdoctoral fellowship of the Junta de Andalucia (Sevilla, Spain), and the European Social Fund 2014-2020 Program (DOC_0055). The authors received national and international funding through the following projects: SILVADAPT.NET (RED2018-102719-T), ESPECTRAMED (CGL2017-86161-R), Life-FOREST CO2 (LIFE14 CCM/ES/001271), ALTERACLIM (CGL2015-69773-C2-1-P), INERTIA (PID2019-111332RB-C22-BDV), CEHYRFO-MED (CGL2017-86839-C3-2-R), DEHESACLIM (IB16185), RESILIENTFORESTS (LIFE17 CCA/ES/000063), Rhysotto (PID2019-106583RB-I00), AGL2017-83828C2-2-R, RTI2018-096884-B-C31, ESPAS (CGL2015-65569-R), and caRRRascal (RTI2018-095037-B-I00).

[EN] Pinus halepensis Miller is a widespread tree species in the western Mediterranean basin, where very dense monospecific stands can be found, especially in natural regeneration after forest fires. Silvicultural thinning can reduce the competition of trees for natural resources and favour their development, although its effect depends on the habitat. The present study aims to know the effects on the soil at the physicochemical and microbiological levels after a heavy thinning in a young pine forest stand with a high stocking density. The stand is on a slope where the soil depth tends to decrease with altitude, and shows changes in its physicochemical properties between the upper and lower zones. Several soil carbon fractions (i.e., soil organic carbon (SOC), water-soluble organic carbon (WSOC), and microbial biomass carbon (MBC)), microbial activity (basal soil respiration (BSR)) and enzyme activities (acid phosphatase (AP) and urease (UA)) were analysed at specific dates over a period of about five years after a heavy thinning. The changes in organic matter content were abrupt in the slope, conditioning the observed differences. It is highlighted that the SOC and WSOC contents in the mineral soil were 2.5- and 3.5-fold significantly higher, respectively, in the upper shallow zone compared to the lower deeper zone. This was also reflected in significantly higher levels of gravimetric water content (GWC) and MBC (both about 1.4-fold higher), with higher levels of BSR and UA, and 2.5-fold significantly higher levels of AP. As a result, most of the properties studied showed no significant differences between the thinning treatment and the untreated control. Results varying between dates, with a strong dependence on climate (soil temperature and humidity) of WSOC and UA. It can be concluded that the heavy thinning applied in this short-term case study favoured the growth conditions of the pine without negatively affecting the soil properties studied., This study is a component of research projects: HYDROSIL (CGL2011-28776-C02-02) and
SILWAMED (CGL2014-58127-C3-2) and CEHYRFO-MED (CGL2017-86839-C3-2-R) funded by the
Spanish Ministry of Science and Innovation.

[EN] Mediterranean drylands are often nutrient poor, but parameter requirements of forest ecosystem models are usually high. Therefore, there is a need for developing parsimonious nutrients models. In that sense, this study aims to contribute to a better understanding and modelling of the hydrological and biogeochemical (carbon and nitrogen) cycles and their interactions in semiarid conditions and to test the capability of a new parsimonious model to satisfactorily reproduce them. The proposed model (TETIS-CN) and two additional widely used models were implemented in a Quercus ilex forest, and no noteworthy differences were found. Results suggest that: (1) it is important to include carbon observations in the calibration process and to consider all the existing vegetation species in the simulation; (2) a fixed daily potential uptake may not be appropriate to reproduce plant nitrogen uptake; and (3) TETIS-CN, with a lower number of parameters, proved an acceptable tool., This work was supported by the Spanish Ministry of Science and Innovation through the research projects: TETISMED (CGL2014-58127-C3-3-R), SILWAMED (CGL2014-58127-C3-2-R), CEHYRFO-MED (CGL2017-86839-C3-2-R) and TETISCHANGE (RTI2018-093717-B100), and by the project LIFE17CCA/ES/000063 RESILIENTFORESTS.

[EN] Water scarcity in semi-arid regions is expected to increase under climate change, which will significantly affect forest ecosystems by increasing fire risk, diminishing productivity and water provisioning. Eco-hydrological forest management is conceived here as an adequate strategy to buffer climate change effects and increase forest resilience. Under this context, soil moisture is a key variable to quantify the impacts of eco-hydrological forest management on forest-water relations. Cosmic-ray neutron and capacitance probes are two different techniques for measuring soil moisture, which differ greatly in the spatial scale of the measurement support (i.e., few centimeters vs. several hectares). This study compares the capability of both methodologies in assessing soil water dynamics as a key variable that reflects the effects of forest management in a semi-arid environment. To this end, two experimental plots were established in Sierra Calderona in the province of Valencia in Spain in a post-fire regeneration Aleppo pine forest with high tree density. One plot was thinned (T) and the other remained as control (C). Nine capacitance probes and one Cosmic Ray Neutron Probe (CRNP) were installed in each plot. First, the CRNP was calibrated and validated, and subsequently, the performance of both techniques was analyzed by comparing soil moisture and its relationship with environmental variables and stand transpiration. The validation results confirmed the general reliability of CRNP to obtain soil moisture under semi-arid conditions, with a Kling-Gupta efficiency coefficient (KGE) between 0.75 and 0.84, although this performance decreased significantly when dealing with extreme soil moisture (KGE: -0.06-0.02). A significant effect of forest biomass and litter layer was also observed on CRNP-derived soil moisture, which produced an overestimation of soil moisture. The performance of both methodologies was analyzed by partial correlations between soil moisture and environmental variables and transpiration, as well as by applying Boosted Regression Trees to reproduce tree transpiration with each soil moisture measurement technique together with the environmental variables. Both methodologies were capable to reproduce tree transpiration affected by soil moisture, environmental variables and thinning, although CRNP always appeared as the most affected by atmospheric driving forces., This study is a component of the research projects: EHIDROMED (CGL2014-58127-C3) and CEHYRFO-MED (CGL2017-86839-C3-2-R) funded by the Spanish Ministry of Science and Innovation and FEDER funds, and LIFE17 CCA/ES/000063 RESILIENTFORESTS. AM is beneficiary of an APOSTD fellowship (APOSTD/2019/111) funded by the Generalitat Valenciana.

[EN] Soil organic carbon pools have an important role in the maintenance of ecosystems as a source of energy for soil microorganisms. Soil biological and biochemical properties are essential for the decomposition of organic matter. These soil properties can be affected by thinning, which is considered sustainable when the soil properties are maintained or improved. We studied the effects of selective thinning and shrub clearing, performed with an ecohydrological approach, in a marginal Holm oak forest in a semiarid area on soil properties. The effects of thinning (T) were compared with an untreated area (control, C). Fine woody debris was ground into mulch onto the thinned area. Forest floor and mineral soil properties were analyzed between five months and seven years after the thinning. In the forest floor, gravimetric water content (GWc(ff)) and water soluble organic carbon (WSOCff) were analyzed and compared between T and C. In mineral soil, GWC(ms), soil organic carbon (SOC), WSOCms, soil basal respiration (BR), soil microbial biomass carbon (MBC) and soil enzymes (acid phosphatase (Acid PA) and urease (URE)) were analyzed. In the early stage, the results showed slightly higher SOC and WSOms in T likely due to fine woody debris left on the forest floor. However, seven years after the thinning the effects of the thinning on all the studied variables were negligible. All variables showed high spatial-temporal variability. Our results suggest that selective thinning and shrub clearing in the studied site do not affect negatively soil properties when woody debris is left on the forest floor., This study is a component of research projects: HYDROSIL (CGL2011-28776-C02-02) and SILWAMED (CGL2014-58+127-C3-2), RESILIENT-FORESTS (LIFE17 CCA/ES/000063) and CEHYRFO-MED (CGL2017-86839-C3-2-R) funded by the Spanish Ministry of Science and Innovation, and the FEDER fund and the EU. The authors are grateful to the Valencia Regional Government (CMAAUV, Generalitat Valenciana) for it supports in allowing the use of the experimental forest. We thank Joana Oliver for her laboratory and technical assistance and Dr. Rafael Herrera for valuable comments on the manuscript.

[EN] Water-oriented forest management is an urgent need in semiarid catchments. In the case of low-biomass forests and shrublands, the magnitude, efficiency and temporal duration of thinning effects on rainfall partitioning needs further attention. This work studies the effects of juvenile thinning and shrub clearing on stemflow (Stf), throughfall (Thr) and interception (It) in two low-biomass forests (CAL: post-fire Aleppo pine saplings with 74% of basal area, BA, removed; and HU: evergreen oak coppice with 41% of BA removed), as well as the relative contribution of the event meteorology. The effects are compared with a control plot during the first 3¿4¿years. Stf rate (%) decreased with density and, on a tree scale, it was enhanced by the treatment only in the bigger oaks. Event Thr increased from 55 to 81% and from 68 to 86% of gross rainfall (Pg) for CAL and HU respectively after thinning, resulting in about 15% less intercepted Pg. High evaporative conditions and an open (ventilated) forest structure led to high It rates in the controls when comparing with other studies, thus making the treatments more efficient in net precipitation (Pn) gain (Pg intercepted decreased 17% or 2.3% per unit of LAI or BA removed respectively). In general, depths (mm) were mostly explained (>75%) by the rainfall characteristics of the event (e.g. amount, duration, intensity), with a limited contribution from forest structure (e.g. cover, LAI) and event meteorology (e.g. temperature, wind speed, vapor pressure deficit). On the contrary, when expressed as rates (% of Pg), forest structure and event-meteorology gained importance (explaining 25¿65%), especially in the drier site (CAL). In this site, the low gain in Pn (~25¿mm per year on average) was offset with no temporal dampening during the span of this study, as observed in the wetter site (HU), where plant growth tended to mitigate the effect of the treatment by the end of the study. The results presented here make a contribution to a better understanding of the effects of water-oriented forest management in low-biomass semiarid forests., This study is a component of research projects: HYDROSIL (CGL2011-28776-C02-02), SILWAMED (CGL2014-58127-C3-2) and CEHYRFO-MED (CGL2017-86839-C3-2-R) funded by the Spanish Ministry of Science and Innovation and the FEDER fund of the EU. The authors are grateful to the Valencia Regional Government (CMAAUV, Generalitat Valenciana), Serra municipality, VAERSA and ACCIONA for their support in allowing the use of the experimental forest and for their assistance in carrying out the fieldwork.

Adaptive forest management (AFM) is an urgent need because of the uncertainty regarding how changes in the climate will affect the structure, composition and function of forests during the next decades. Current research initiatives for the long-term monitoring of impacts of silviculture are scattered and not integrated into research networks, with the consequent losses of opportunities and capacity for action. To increase the scientific and practical impacts of these experiences, it is necessary to establish logical frameworks that harmonize the information and help us to define the most appropriate treatments. In this context, a number of research groups in Spain have produced research achievements and know-how during the last decades that can allow for the improvement in AFM. These groups address the issue of AFM from different fields, such as ecophysiology, ecohydrology and forest ecology, thus resulting in valuable but dispersed expertise. The main objective of this work is to introduce a comprehensive strategy aimed to study the implementation of AFM in Spain. As a first step, a network of 34 experimental sites managed by 14 different research groups is proposed and justified. As a second step, the most important AFM impacts on Mediterranean pines, as one of the most extended natural and planted forest types in Spain, are presented. Finally, open questions dealing with key aspects when attempting to implement an AFM framework are discussed. This study is expected to contribute to better outlining the procedures and steps needed to implement regional frameworks for AFM., A.J. Molina is beneficiary of an “APOSTD” fellowship (APOSTD/2019/111) funded by the Generalitat Valenciana. M. Moreno-de las Heras is beneficiary of a Serra Hunter fellowship (UB-LE-9055) funded by the Generalitat de Catalunya. F.J. Ruiz-Gómez is supported by a postdoctoral fellowship of the Junta de Andalucía (Sevilla, Spain), and the European Social Fund 2014–2020 Program (DOC_0055). The authors received national and international funding through the following projects: SILVADAPT.NET (RED2018-102719-T), ESPECTRAMED (CGL2017-86161-R), Life-FOREST CO2 (LIFE14 CCM/ES/001271), ALTERACLIM (CGL2015-69773-C2-1-P), INERTIA (PID2019-111332RB-C22-BDV), CEHYRFO-MED (CGL2017-86839-C3-2-R), DEHESACLIM (IB16185), RESILIENTFORESTS (LIFE17 CCA/ES/000063), Rhysotto (PID2019-106583RB-I00), AGL2017-83828-C2-2-R, RTI2018-096884-B-C31, ESPAS (CGL2015-65569-R), and caRRRascal (RTI2018-095037-B-I00).