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Carbon accounting in the land sector requires a reference level from which to calculate past losses of carbon and potential for gains using a stock-based target. Carbon carrying capacity represented by the carbon stock in primary forests is an ecologically-based reference level that allows estimation of the mitigation potential derived from protecting and restoring forests to increase their carbon stocks. Here we measured and collated tree inventory data at primary forest sites including from research studies, literature and forest inventories (7982 sites, 288,262 trees, 27 countries) across boreal, temperate, and subtropical Global Ecological Zones within Europe. We calculated total biomass carbon stock per hectare (above- and below-ground, dead biomass) and found it was 1.6 times larger on average than modelled global maps for primary forests and 2.3 times for all forests. Large trees (diameter greater than 60 cm) accounted for 50% of biomass and are important carbon reservoirs. Carbon stock foregone by harvesting of 12–52% demonstrated the mitigation potential. Estimated carbon gain by protecting, restoring and ongoing growth of existing forests equated to 309 megatons carbon dioxide equivalents per year, additional to, and higher than, the current forest sink, and comparable to the Green Deal 2030 target for carbon dioxide removals.

Thermodynamics is a vast area of knowledge with a debatable role in explaining the evolution of ecosystems. In the case of soil ecosystems, this role is still unclear due to difficulties in determining the thermodynamic functions that are involved in the survival and evolution of soils as living systems. The existing knowledge is largely based on theoretical approaches and has never been applied to soils using thermodynamic functions that have been experimentally determined. In this study, we present a method for the complete experimental thermodynamic characterization of soil organic matter. This method quantifies all the thermodynamic functions for combustion and formation reactions which are involved in the thermodynamic principles governing the evolution of the universe. We applied them to track the progress of soil organic matter with soil depth in mature beech forests. Our results show that soil organic matter evolves to a higher degree of reduction as it is mineralized, yielding products with lower carbon but higher energy content than the original organic matter used as reference. These products have higher entropy than the original one, demonstrating how the soil ecosystem evolves with depth, in accordance with the second law of thermodynamics. The results were sensitive to soil organic matter transformation in forests under different management, indicating potential applicability in elucidating the energy strategies for evolution and survival of soil systems as well as in settling their evolutionary states.

The role of plantations as active carbon sinks is widely recognized, their rapid growth over a short time period makes them important contributors to climate change mitigation. The construction of root production models based on the leaf index area could provide an interesting predictive tool for estimating the contribution of roots in terms of carbon, particularly given the difficulty involved in the direct estimation of this fraction and its potential importance in terms of carbon in the soil. The data used for this study came from a poplar short rotation plantation of the highly productive genotype of Populus x canadensis Mönch, established in central Spain in 2017 at a density of 10,000 trees ha-1. A potential non-linear model, which relates root biomass to leaf area index, is presented. The results indicate an explained variance of 0.881. Root biomass of polar plantations under Mediterranean conditions plays a key role in increasing and/or restoring C stocks in the soil, the C carbon content in the root biomass being 5.81 Mg C ha-1 per rotation cycle. This study helps to further our knowledge regarding the real carbon balance of these plantations under Mediterranean environments. © 2022, ETA-Florence Renewable Energies.

The thermodynamic characterization of the soil organic matter could be achieved by different enthalpic models little explored for soil. This paper compares two of them for calculating the enthalpy change, the Gibbs energy change and the entropy change of the soil organic matter combustion reaction, by simultaneous differential scanning calorimetry and thermogravimetry. Soil samples were collected in beech and oak forests from different geographical areas, and at different depths to represent the L/F horizon and the mineral soil, at each sampling site. The thermodynamic state variables were calculated using two different enthalpic models, to examine how they differed in relation to different types of SOM and different forest ecosystems. Both models yielded thermodynamic variables, which although closely and significantly correlated, were statistically significantly different. All the thermodynamic variables depended on the different forest types and the different nature of the soil organic matter under study. Results allowed to discern which of the models applied better to the SOM combustion reaction designed.

Studying the thermodynamic properties of soil organic matter is a developing field that involves the measurement of the energy stored by the soil. Quantifying soil energy content is still challenging despite different methodological approaches are available to calculate that value. One of the options is the proximate analysis following the guidelines for the energetic characterization of biomass. However, proximate analyses are still unexplored for soils. In this paper, we investigate the potential of this analysis to contribute to study soil from a thermodynamic perspective. With that goal, 31 soil samples collected in mature oak forests following a depth transect were used for elemental, thermal and proximate analysis. Proximate analyses and energetic characterization were performed by simultaneous thermogravimetry and differential scanning calorimetry

The important role that forests play in the global carbon cycle has led to the implementation of management practices to enhance long-term carbon storage in forests. Obtaining information about how forest biomass varies at different successional stages is therefore essential. In this study, we aimed (i) to determine the relationship between stand live biomass and the degree of naturalness (i.e. the degree to which forests dynamics are driven by natural processes in the absence of anthropogenic influences) in undisturbed, mature forests, and (ii) to establish the upper threshold of live biomass stock that is dependent on site quality, by using the site form (SF) index (dominant height-diameter relationship). We assessed live biomass stocks in a total of 10 undisturbed mixed and pure mature silver fir (Abies alba Mill.) and European beech (Fagus sylvatica L.) stands across the Spanish Pyrenees. We used dendrochronology and chrono-functional indicators to assess the degree of naturalness and to detect growth releases as proxies for past disturbance. We compared data from the mature plots and data from the Spanish National Forest Inventory (NFI), for similar forest types and SF values, to determine whether maximum live biomass values were reached in the plots. We observed that live biomass stock was generally independent of naturalness. The forests characterized by the lowest degrees of naturalness held similar amounts of live tree biomass as those characterized by the highest degrees of naturalness, including old-growth forests. Although some stands had undergone severe disturbance in the past, in all but two plots the live biomass stocks reached maximum values at the respective SF values, unlike in the NFI plots. The study findings contribute to the body of evidence supporting the existence of an upper threshold of live biomass stock represented by undisturbed mature stands. Maximum live carbon stock appears to be reached at earlier stages than the old-growth stage. T

Estimation of forest maturity linked to the biomass (or carbon) stock capacity is considered one of the most important issues regarding forest management and planning. This doctoral thesis explores such relationships and considers the use of stand level maximum biomass stock as a proxy for forest maturity through site quality gradient, as a measure that can feasibly be estimated from National Forest Inventory data. The research study was conducted in Spain for maritime pine (Pinus pinaster ssp. atlantica H. de Vill.), Scots pine (Pinus sylvestris L.), beech (Fagus sylvatica L.), beech-fir and silver fir (Abies alba Mill.) forests. Finally, the potential of terrestrial laser scanning (TLS) technology for estimating forest features in mature stands was also explored. For this purpose, the R package FORTLS was developed.

Este libro contiene las actas del Workshop sobre Teledetección Próxima Terrestre para Aplicaciones Forestales que tuvo lugar los días 1, 2 y 3 de septiembre de 2021 en la Escuela Politécnica Superior de Ingeniería del Campus Terra de la Universidade de Santiago de Compostela (Lugo, España). Este workshop tuvo como objetivo la puesta en común de resultados científicos y aplicaciones prácticas de estas tecnologías en el ámbito forestal, así como la práctica de aspectos operativos en la toma y análisis de datos. Para ello, constó de jornadas científico-técnicas con formato de congreso (híbrido presencial-telemático), sesiones prácticas de toma de datos en campo y de su posterior análisis y procesado en ordenador mediante la impartición de talleres (presencial), y de una mesa redonda de reflexión sobre el estado del arte de estas tecnologías en todos los ámbitos forestales implicados. Este evento fue organizado conjuntamente por los grupos de investigación GI-1716 Proyectos y Planificación (PROEPLA) y GI-1837 Unidad de Gestión Ambiental y Forestal Sostenible (UXAFORES) de la Universidade de Santiago de Compostela. La celebración del workshop fue financiada por la Diputación de Lugo y la Universidade de Santiago de Compostela, a través de la Convocatoria de axudas 2021 para a realización de actividades de investigación e/ou transferencia no ámbito do desenvolvemento rural no Campus de Lugo, y por la Consellería de Educación, Universidade e Formación Profesional de la Xunta de Galicia que, mediante el Programa de Consolidación y Estructuración de Unidades de Investigación Competitivas, financia los grupos de referencia competitiva PROEPLA (GRC GI-1716, ED431C 2021/27) y UXAFORES (GRC GI-1837, ED431C 2018/07). Además, el evento fue patrocinado por las empresas ÁLAVA INGENIEROS y GRAFINTA, que han participado como sponsors vinculados a dos de las tecnologías de teledetección próxima terrestre objeto de la actividad: escáner láser terrestre (TLS) y localización simultánea y

Terrestrial Laser Scanning (TLS) devices show great potential for application in Forest Inventories (FIs) as they are capable of registering high resolution point clouds rapidly and automatically. Nevertheless, operational use of TLS for FI purposes has been hampered by the absence of algorithms for processing the acquired data, particularly in the single-scan mode, as occlusions result in loss of information. The R package FORTLS has been developed to overcome this obstacle, as it automates the processing of single-scan TLS point cloud data for forestry purposes and includes several features that deal with occlusions. FORTLS makes use of the main advantage of the single-scan scenario in FI, thus improving the efficiency of data acquisition and post-processing. All of these features of the FORTLS package are potentially valuable for the operational use of TLS in FIs, in combination with inference techniques derived from model-based and model-assisted approaches

Ecological knowledge on long-term forest dynamics and development has been primarily derived from the study of old-growth forests. Centuries of forest management have decreased the extent of temperate old-growth forests in Europe and altered managed forests. Disentangling the effects of past human disturbances and climate on current species composition is crucial for understanding the long-term development of forests under global change. In this study, we investigated disturbance and recruitment dynamics in two forests in the Western Pyrenees (Spain) with contrasting management history: an old-growth forest and a long-untouched forest, both dominated by the two shade-tolerant species Fagus sylvatica (European beech) and Abies alba (Silver fir). We used dendroecological methods in seven plots to analyse forest structure, growth patterns and disturbance histories in these forests. We benchmarked these data with the dynamic vegetation model ForClim to examine the effects of natural and human-induced disturbances on forest development, structure and species composition. Disturbance regimes differed between the study forests, but none showed evidence of stand replacing disturbances, either natural or human induced. Low disturbance rates and continuous recruitment of beech and fir dominated the old-growth forest over the last 400 years. In contrast, the long-untouched forest was intensively disturbed in 1700–1780, probably by logging, with lower natural disturbance rates thereafter. Beech and fir recruitment preferentially occurred after more intense disturbances, despite the high shade tolerance of both beech and fir. Higher fir abundance in the long-untouched forest than in the old-growth forest appeared to be related to its human-induced disturbances. ForClim closely simulated forest potential natural vegetation with a dominance of beech over fir, but overestimated the presence of less shade-tolerant species. Previously observed local fir decline may result from natura

Poplar (Populus spp.) Short Rotation Coppice (SRC) systems are characterized by high short-term biomass pro ductivity and play a key role in promoting employment in rural areas as well as supplying environmental benefits. However, in the context of climate change with expected reduced water availability in the Mediter ranean area, the productivity of these plantations may be seriously limited. In this regard, the aim of this work is to analyse the monthly dynamic responses of relevant variables at foliar level throughout the entire first rotation of a poplar short rotation plantation under two water scenarios: optimal scenario (with irrigation to field capacity (FC)) versus restrictive scenario (with 50% FC irrigation). This data came from 590 trees in a poplar short rotation plantation of the highly productive genotype ‘AF2‘. LAImax values of 2.39, 7.47 and 9.34 were found for the three-year rotation cycle, pointing to significantly lower values after the establishment year under the restrictive water scenario. SLA mean values displayed a downward trend, with 12.25 m2 kg− 1 , 10.82 m2 kg− 1 and 10.47 m2 kg− 1 for years 1, 2 and 3 respectively, no significant differences being observed between water scenarios. NPK foliar concentrations decreased over the rotation, being the values lower under the restrictive scenario. Additionally, the selected genotype, ‘AF2’, displayed tight stomatal control under conditions of water stress, maintaining high photosynthetic levels. The responses observed in this study can potentially be used to better understand the behavior of these var iables which most affect production of poplar plantations in face of climate change.

Developing a circular bioeconomy based on the sustainable use of biological resources, such as biomass, seems to be the best way of responding to the challenges associated with global change. Among the many sources, short rotation forest crops are an essential instrument for obtaining quality biomass with a predictable periodicity and yield, according to the areas of cultivation. This review aims to provide an overview of available knowledge on short rotation coppice Populus spp. plantations under Mediterranean conditions and specifically in Spain, in order to identify not only the status, but also the future prospects, for this type of biomass production. The analysis of available information was conducted by taking into consideration the following aspects: Genetic plant material; plantation design, including densities, rotation lengths and the number of rotations, and mixtures; management activities, including irrigation, fertilization, and weed control; yield prediction; biomass characterization; and finally, an evaluation of the sustainability of the plantation and ecosystem services provided. Despite advances, there is still much to be done if these plantations are to become a commercial reality in some Mediterranean areas. To achieve this aim, different aspects need to be reconsidered, such as irrigation, bearing in mind that water restrictions represent a real threat; the specific adaptation of genetic material to these conditions, in order to obtain a greater efficiency in resource use, as well as a greater resistance to pests and diseases or tolerance to abiotic stresses such as drought and salinity; rationalizing fertilization; quantifying and valuing the ecosystem services; the advance of more reliable predictive models based on ecophysiology; the specific characterization of biomass for its final use (bioenergy/bioproducts); technological improvements in management and harvesting; and finally, improving the critical aspects detected in environmental, ene

Terrestrial Laser Scanning (TLS) enables rapid, automatic, and detailed 3D representation of surfaces with an easily handled scanner device. TLS, therefore, shows great potential for use in Forest Inventories (FIs). However, the lack of well-established algorithms for TLS data processing hampers operational use of the scanner for FI purposes. Here, we present FORTLS, which is an R package specifically developed to automate TLS point cloud data processing for forestry purposes. The FORTLS package enables (i) detection of trees and estimation of their diameter at breast height (dbh), (ii) estimation of some stand variables (e.g., density, basal area, mean, and dominant height), (iii) computation of metrics related to important tree attributes estimated in FIs at stand level, and (iv) optimization of plot design for combining TLS data and field measured data. FORTLS can be used with single-scan TLS data, thus, improving data acquisition and shortening the processing time as well as increasing sample size in a cost-efficient manner. The package also includes several features for correcting occlusion problems in order to produce improved estimates of stand variables. These features of the FORTLS package will enable the operational use of TLS in FIs, in combination with inference techniques derived from model-based and model-assisted approaches

In this study, a comprehensive analysis of deadwood was conducted in four macro-areas located in two beech forests of public utility in Enciso (La Rioja, Spain). Dendrometric data, as well as qualitative and quantitative characteristics of deadwood, were collected and analysed with respect to the degree of accessibility to the forest to determine the effect of different levels of forest accessibility on deadwood volume and carbon stocks. All decomposition classes were present except the first, highlighting the development of natural degradation dynamics. Deadwood stored 6.9 t/ha of C in the easy accessibility class, 5.7 t/ha of C in the medium accessibility class and 2.2 t/ha of C in the difficult accessibility class. The average volume of deadwood and carbon stored calculated in this study were higher than the values reported in the Spanish and Italian national forest inventories, including one developed for Riojan beech forests. Deadwood volume was on average 22.5 m3/ha, showing an unequal distribution, with the lowest values found far from the access roads, despite forest accessibility generally being considered a factor that facilitates the human collection of deadwood. The distribution patterns of deadwood in beech forests of La Rioja, apparently counterintuitive, were due to a combination of different factors, including slope, cattle grazing, and weather conditions which might have favoured downward movement of the deadwood

Forest biomass is currently among the most important and most researched target variables in forest monitoring. The common approach of observing individual tree biomass in forest inventory is to assign the total tree biomass to the dimensionless point of the tree position. However, the tree biomass, in particular in the crown, is horizontally distributed above the crown projection area. This horizontal distribution of individual tree biomass (HBD) has not attracted much attention—but if quantified, it can improve biomass estimation and help to better represent the spatial distribution of forest fuel. In this study, we derive a first empirical model of the branch HBD for individual trees of European beech (Fagus sylvatica L.). We destructively measured 23 beech trees to derive an empirical model for the branch HBD. We then applied Terrestrial Laser Scanning (TLS) to a subset of 17 trees to test a simple point cloud metric predicting the branch HBD. We observed similarities between a branch HBD and commonly applied taper functions, which inspired our HBD model formulations. The models performed well in representing the HBD both for the measured biomass, and the TLS-based metric. Our models may be used as first approximations to the HBD of individual trees—while our methodological approach may extend to trees of different sizes and species