Interactions between climate, growth and seed production in Spanish black pine (Pinus nigra Arn. ssp. salzmannii) forests in Cuenca Mountains (Spain)

Tree growth is regulated by a combination of exogenous and endogenous factors. Such factors also interact with each other, complicating the understanding of causal links. IN particular, resource allocation is sensitive to reproductive investment, especially in masting species, which in turn is regulated by climatic variables. Both resource allocation and seed production patterns are also sensitive to tree age. This study aims to (1) evaluate the effects of tree age and local and regional climate on tree ring width and seed production by Spanish black pine (Pinus nigra Arn. ssp. salzmannii) forest in Cuenca Mountains (Spain), and (2) assess the relationship between seed production and secondary growth of Spanish black pine. Seed fall was estimated using 60 rectangular seed traps (40 x\u97 50 x\u97 15 cm) from 2000 to 2014, randomly distributed across the study area. Standardized tree-ring chronologies were calculated using a random sample of 106 trees stratified into three age classes (> 80 years; 26-\u80\u9380 years, and < 25 years). Local climate data was obtained from a meteorological station, and regional climate data from the CRU-TS 3.1 dataset. Average seed production ranged over time from 2 to 189 seeds m\u88\u922(coefficient of variation = 157%). We identified four masting years (2000, 2003, 2006, and 2014) using a classification based on percentile seed production. Seed production was regulated by climate of the previous 2-3 years, while tree growth responded to precipitation and temperature in the previous and current year. Independent of climate, high seed production had a negative effect on tree ring width and weakened climate growth relationships, indicating resource depletion. Tree age modulated climate sensitivity, increasing correlations between climate and tree-ring index in older trees. P. nigra has been showed to be a climate sensitive species with a bimodal masting behaviour, which should be taking into account for management purposes and silvicultural guidelines under climate change scenarios

Influencia de los métodos de conservación en las actividades enzimáticas de suelos forestales mediterráneos

Soil storage method may alter enzymatic activity being storage conditions of the soil samples prior to analysis decisive for the results. Studies made on freshly collected soils are generally preferred. However it is always not possible due to practical reasons since for example sampling is often restricted to short period of the year or because a great quantity of microbiological analyses must be made on time and by few people. On this context, soil storage methods are needed, being cold at 4°C the most widely used although sometimes alternative storage methods are also utilized. The aim of this study is to evaluate the effect of two alternative storage methods of soil samples (freezing at –20°C and air drying conservation methods) in comparison to cold at 4°C on the enzymatic activities (dehydrogenase, phosphatase, β-glucosidase and urease soil enzymes). Samples of two forest ecosystems (pine and holm oak forest stand) were taken in two different season of the year (winter and spring 2009). Results showed that enzymatic activities differed when freezing or air drying conservation methods were used in comparison with cold soil samples. Generally, alternative soil storage methods presented lower enzymatic activity than cold at 4°C. However, these changes depend on season and sampling location.El método de conservación del suelo utilizado puede alterar la actividad enzimática, siendo decisivas para los resultados, las condiciones de conservación previas a los análisis. Para los estudios es preferible realizar los análisis en muestras frescas y recién cogidas. Sin embargo, esto no es siempre posible por razones prácticas ya que las muestras se tienen que recoger en un corto periodo del año o porque los análisis los debe hacer poca gente y siempre en un determinado tiempo. En este contexto, se necesita un método de conservación, siendo el mantenimiento en el frigorífico a 4°C el método más usado, aunque existen otros métodos alternativos. El objetivo de este trabajo es el de evaluar el efecto de dos métodos alternativos de conservación (congelado a –20°C y secado a temperatura ambiente) sobre las actividades enzimáticas (deshidrogenasa, fosfatasa, β-glucosidasa y ureasa), en comparación con el mantenido en el frigorífico a 4°C. Las muestras se obtuvieron de dos zonas forestales diferentes (pinar y encinar) y en dos épocas distintas (primavera y verano de 2009). Los resultados mostraron diferencias en las actividades enzimáticas cuando se usó el congelado o secado al aire de las muestras de suelo en comparación con el mantenimiento en el frigorífico. De forma general, los métodos de conservación alternativos mostraron una menor actividad enzimática en las muestras de suelo analizadas. Sin embargo, estos cambios dependen de la época del año y la zona de muestreo

Temporal characterisation of soil-plant natural recovery related to fire severity in burned Pinus halepensis Mill. forests

Despite Mediterranean ecosystems' high resilience to fire, both climate and land use change, and alterations in fire regimes increase their vulnerability to fire by affecting the long-term natural recovery of ecosystem services. The objective of this work is to study the effects of fire severity on biochemical soil indicators, such as chemical composition or enzymatic activity, related to time after fire and natural vegetation recovery (soil-plant interphase). Soil samples from three wildfires occurring 3, 15 and 21 years ago were taken in the south-eastern Iberian Peninsula (semiarid climate). Sampling included three fire severity levels in naturally regenerated (and changing to shrublands) Pinus halepensis Mill. forests. In the short-term post-fire period, phosphorus concentration, electrical conductivity and urease activity were positively linked to fire severity, and also influenced β-glucosidade activity in a negative relationship. During the 15–21-year post-fire period, the effects related to medium-high fire severity were negligible and soil quality indicators were linked to natural regeneration success. The results showed that most soil properties recovered in the long term after fire (21 years). These outcomes will help managers and stakeholders to implement management tools to stabilise soils and to restore burned ecosystems affected by medium-high fire severity. Such knowledge can be considered in adaptive forest management to reduce the negative effects of wildfires and desertification, and to improve the resilience of vulnerable ecosystems in a global change scenario.This study was supported by a grant for research initiation provided by the Excma. Diputación Albacete (DIPU4-AB2015) and by the funds provided by University Castilla-La Mancha to the Forest Ecology Research Group.The authors with to thank the Spanish Institute for Agricultural and Food Research and Technology (INIA) for the funding awarded through National Research Projects GEPRIF (RTA2014-00011-C06)

Current Wildland Fire Patterns and Challenges in Europe: A Synthesis of National Perspectives

Changes in climate, land use, and land management impact the occurrence and severity of wildland fires in many parts of the world. This is particularly evident in Europe, where ongoing changes in land use have strongly modified fire patterns over the last decades. Although satellite data by the European Forest Fire Information System provide large-scale wildland fire statistics across European countries, there is still a crucial need to collect and summarize in-depth local analysis and understanding of the wildland fire condition and associated challenges across Europe. This article aims to provide a general overview of the current wildland fire patterns and challenges as perceived by national representatives, supplemented by national fire statistics (2009–2018) across Europe. For each of the 31 countries included, we present a perspective authored by scientists or practitioners from each respective country, representing a wide range of disciplines and cultural backgrounds. The authors were selected from members of the COST Action “Fire and the Earth System: Science & Society” funded by the European Commission with the aim to share knowledge and improve communication about wildland fire. Where relevant, a brief overview of key studies, particular wildland fire challenges a country is facing, and an overview of notable recent fire events are also presented. Key perceived challenges included (1) the lack of consistent and detailed records for wildland fire events, within and across countries, (2) an increase in wildland fires that pose a risk to properties and human life due to high population densities and sprawl into forested regions, and (3) the view that, irrespective of changes in management, climate change is likely to increase the frequency and impact of wildland fires in the coming decades. Addressing challenge (1) will not only be valuable in advancing national and pan-European wildland fire management strategies, but also in evaluating perceptions (2) and (3) against more robust quantitative evidence

Environmental and ecological factors influencing soil functionality of biologically crusted soils by different lichen species in dryland

Biocrusts are an essential soil surface cover at drylands where ecosystems are especially fragile to soil degradationprocesses due to climatic peculiarities. In the present work, (micro)biological and physicochemical properties indic-ative of soil functionality were studied in two different biocrust types dominated byDipolschistes diacapsisandLepraria isidiataand in underlying soil at two different depths (SL1, soil layer right below the biocrusts, and SL2,soil layer underlying SL1) at the Tabernas desert (southeast Spain). The influence of climatic factors (rainfall andtemperature) and general soilproperties on the (micro)biological properties were also analyzed in different envi-ronmental (climatic) conditions over a period of two years. PERMANOVA analyses showed significant statisticaldifferences (Pseudo-F = 63.9; P (perm) = 0.001) among biocrust and soil layers. Throughout the study period, en-zyme activities involved in C, N, and P cycles; microbial biomass-C; basal respiration; and several properties directlyrelated to ecosystem productivity (total organic carbon, total nitrogen, concentration of ammonium and nitrate)were higher in both biocrust types than in the underlying soil layers, showing that biocrusts improved soil functionsrelated to nutrient cycling. These properties progressively diminished in successive soil layers under the biocrusts(biocrusts > SL1 > SL2). Biocrusts showed greater similarity to each other and to SL1 than to SL2 in (micro)biologicalproperties. A distance-based linear model analysis showed that total organic carbon, rainfall, pH, mineralized N-NH4+, and total nitrogen were the most important variables for predicting (micro)biological soil properties inbiocrusts. Different biochemical behavior between the biocrusts and successive underlying soil layers has beenfound in wet periods. After rainfall periods, the biocrusts showed important peaks in basal soil respiration and in en-zyme activities involved in C and P cycles. Nevertheless, soil biochemical properties hardly showed any peak in SL1anddidnotchangeinSL2despitesoilmoisturebeinghigherinthesoillayersbelowthebiocrusts.Correlationanal-yses corroborated the existence of different relationships between soil moisture and enzymatic activities. In biocrusts, soil moisture showed a greater number of significant positive correlations with enzymes such asβ-glucosidase, invertase, and phosphomonoesterase among others, whereas in SL1 it was only correlated with cellu-lase and in SL2 with dehydrogenase. A change in rainfall regime, as predicted by models based on climate changein arid and semiarid zones, could affect the activity of soil enzymes in the biocrusts and underlying layers, thus ag-gravating the degradation of these fragile dryland ecosystems.This study was funded by the Spanish Ministry of Economy and Competitiveness (MINECO) and FEDER, through the project CGL2017-88734-R (BIORESOC) MINECO/AEI/FEDER, UE, the FEDER-Junta deAndalucía Research Projects: RESTAGRO (UAL18-RNM-A021-B) andRestoration of Abandoned Agricultural Soils in Semiarid Zones toImprove Productivity and Soil Quality and Enhance Carbon Sequestra-tion (P18-RT-4112), and by the Xunta de Galicia by the projectIN607A 2017/6. Isabel Miralles is grateful for funding received fromthe Ramón y Cajal Research Grant (RYC-2016-21191) from the SpanishMinistry of Economy,Industry andCompetitiveness (MINECO)and Raúl Ortega thanks his postdoctoral contract HIPATIA of the University of Almería Research Plan.Peer reviewe

Régénération et croissance initiale de Pinus nigra Arn. ssp salzmannii dans les sites chauds et secs : rôle de la provenance de la graine et du sol

International audienceCurrent decreasing precipitation and increasing temperatures promote the likelihood of extreme drought events and may alter the recruitment capacities of tree species. Spanish black pine (Pinus nigra ssp. salzmannii) initial recruitment is being one of the most affected pine species by changing conditions with alterations in the future species distribution. In this context, a cross-exchange experiment was implemented using an outdoor nursery located in a warmer and drier location for testing different Spanish Black pine seeds and soil provenance combinations in relation to early recruitment and initial seedling growth. Soil and seeds were collected at a high (HA, 1641 m.a.s.l.) and low (LA, 1099 m.a.s.l.) altitude in Cuenca Mountains (Spain). Then, a cross-sown experiment using HA and LA soils and seeds was set up in an outdoor nursery, which is located in Albacete (704 m.a.s.l.). Soil quality, seedling emergence, seedling survival, initial seedling growth and total seedling dry mass were measured after one year. We found higher seed emergence and seedling survival by combining LA soil with LA seeds or HA soil with HA seeds. Seedlings from LA seeds with both soil origins and seedlings from HA seeds with LA soils allocated more biomass to roots than seedlings from HA sites growing in HA soils under drier and warmer conditions. These results support the idea that autochtonous provenances have the potential to adapt to changing climatic conditions in their habitats

Régénération et croissance initiale de Pinus nigra Arn. ssp salzmannii dans les sites chauds et secs : rôle de la provenance de la graine et du sol

International audienceCurrent decreasing precipitation and increasing temperatures promote the likelihood of extreme drought events and may alter the recruitment capacities of tree species. Spanish black pine (Pinus nigra ssp. salzmannii) initial recruitment is being one of the most affected pine species by changing conditions with alterations in the future species distribution. In this context, a cross-exchange experiment was implemented using an outdoor nursery located in a warmer and drier location for testing different Spanish Black pine seeds and soil provenance combinations in relation to early recruitment and initial seedling growth. Soil and seeds were collected at a high (HA, 1641 m.a.s.l.) and low (LA, 1099 m.a.s.l.) altitude in Cuenca Mountains (Spain). Then, a cross-sown experiment using HA and LA soils and seeds was set up in an outdoor nursery, which is located in Albacete (704 m.a.s.l.). Soil quality, seedling emergence, seedling survival, initial seedling growth and total seedling dry mass were measured after one year. We found higher seed emergence and seedling survival by combining LA soil with LA seeds or HA soil with HA seeds. Seedlings from LA seeds with both soil origins and seedlings from HA seeds with LA soils allocated more biomass to roots than seedlings from HA sites growing in HA soils under drier and warmer conditions. These results support the idea that autochtonous provenances have the potential to adapt to changing climatic conditions in their habitats

Utilisation des barrages de correction torrentielle pour la protection contre l'érosion à l'échelle du bassin versant: un siècle d'histoire et des perspectives

International audienceCheck dams are transverse structures designed and built in watersheds mainly to control water and sediment flows, conserve soil and improve land. Their stabilization role across stream-beds and gullies have been well known since many years. National, regional and local governments have spent in the last century, and still currently spend, important funds for maintenance and new implementations of check dams as basin scale erosion-control measures throughout the world. However, some projects experience disappointing results due to many different circumstances, such as poor construction quality, inadequate check dam location and lack of adequate design criteria. In addition, these structures induce secondary effects: for instance, different studies have pointed that check dams represent one of the most dominant forms of human impact upon mountain fluvial systems, as they disrupt the downstream transfer of water and sediments; observations of channel cross sections and bed material in several studies for instance indicate that check dams may increase erosion ownstream. Furthermore, in spite of many and eminent studies focusing on laboratory and field researches, the complex hydraulic functioning of the structures (in particular for open check dams, proposed to smooth the adverse effects of the traditional structures) is not completely understood. Thus, there is a lack of full knowledge to optimize existing dams and define the best-adapted design to a given site, also considering the variety of factors materials, size, number, type, etc.) of these engineering works and effects (morphological, hydraulic, sedimentary, ecological and so on) played by them. In this communication, we present the preliminary results of an international review process considering more than 200 papers to highlight problems and benefits of check dam construction all over the world. We aim to achieve a detailed comprehension of check dams' effects at watershed scale in soil restoration schemes from the analysis of results reported in global literature (conceptual thinking, field observations, laboratory simulations), in order to contribute to filling the knowledge gaps identified above. This work is intended to represent a starting point to a future perspective to increase the confidence in developing check dams as restoration tools at watershed scale