bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of high calorific value in biomass
Authors: Suarez J. , Castro R. , Maseda F.
Published: May 2024

In order to know the Gross calorific value (GCV) of Biomass is necessary to analyse samples of weight lower than a gram, Because of the small density of this material which make that they are very voluminous samples, so that we can introduce them into combustion camera of the calorímeter in order to realise the tests. Because of that is necessary to study how this factor impacts in the evaluation of GCV of the studied sample. Moreover, it is necessary to know the contents of nitrogen (N) and sulphur (S) of the studied materials because during the tests the nitrogen reacts giving rise to HNO3 and the SO2 is oxidised and if rise to H2SO4. These quimic reactions absorb of detach heat which can mask the obtained values as GCV of the studied sample. As at the beginning of the test we don’t know the contents in N and S of the samples, we are going to study are so that we don’t have realise these determinations in each test, we realise work to see how they can impact this omission in the obtained facts. The study lie in realise tests in which it is supposed that the contents in N or in S are the maximum that these materials can contain and then the same test is repeated with the minimum contain of N or S. After that the differences between the obtained values are studied to the GCV of the original sample in both proves. So we can see how these factors impact in the obtained results. The test were realised in the laboratory using a calorimeter PARR 1261 with isoperibolie determination and evaluating the GCV of hops which had been mashed in order to make an homogeneous sample. In the test we evaluated the effects of the principal factors P, S and N, so that their interactions PxS, PxN, SxN and PxSxN. In order to confirm the obtained results in the tests we realised a statistic calculus of mena middle and the typical deviation and their variations through an analysis of variance so that a proof of the function F of Fisher in order to see the deviations produced in the variance of each one of the studied factors.
Interregional comparative analysis of wild land fires in Spain
Authors: Barjadi M. , Molina D.
Published: May 2024

We groups Spanish mainland provinces in three regions in order to accomplish this study: Northwest (NW), Mediterranean Coast (LM) and Interior (IP) aimed to explain if there are differences in today’s (decade 1986-95) wildland fire regimes. This grouping follows variations in both climatic conditions, human population densities and land uses, which influence fire causes and behavior. We calculate the frequency index (FI = number of fires / 10000 ha of wildlands) and the severity index (SI = area swept by fire ( 100 / total area of wildands). The latest index was recalculated for both forested and non-forested wildlands. Northwest region has higher FI (27.9) than Interior (4.1) and Mediterranean Coast (6.1) regions. Although frequency indexes for Interior and Mediterranean Coast are lower, the ratio area swept by fire over total forest area do not differ from Northwest ratio. Northwest region has SI values for non-forested wildlands (2.0) higher than other regions (0.4 for IP; and 0.8 for LM). Careful characterization of these regions through meteorological and social factors can help to understand those differences, especially the ones regarding causes.
Reforestation experiments of canarian thermophylus forests
Authors: Gonzalez Artiles F.
Published: May 2024

The results of four thermophilous forests restorations done in Gran Canaria (Canary Islands) are shown. The soil and climatic characteristics of the four plots are described, as well as the percentages of survivorship, the evolution of heights and basal diameters during the experiencie and their correlations. The aim of this study is to know the viability of this works, and to compare the development of the species used in this kind of ecological restorations. In base of their survival and development, Pistacia atlantica and Olea europaea subsp. cerasiformis show the best results.
Plough effect in Eucalyptus globulus biomass growing in southwest Spain
Authors: Donoso S. , Obispo A. , Sanchez C. , Ruiz F. , Herrera M. A.
Published: May 2024

The aim of the study was to asses the plough effects in the above and below ground biomass Eucalyptus globulus plantations. At the same time the root damage was evaluated. The project was carried out in two experimental stands, three trees were chosen by stand and plought treatment. The above ground biomass was determining harvesting the tree. The coarse and fine root were evaluated in 3.6 and 0.688 m3 of soil volume, respectively. Furthermore the root damage were analized in 50 trees. Afterward the predawn leaf water potential were determining in plough and unplough trees. The total above ground biomass have not statistical differences between treatments. The coarse roots represent a high percentage of the below ground biomass and the fine root biomass is higher near the stump. The plough effect was concentrated within the 0-20 cm soil profile. In the plough assay the amount of fine root was higher in the undisturbed than in ploughed soil. Greater part of more superficial fine roots were cuted and linearly decrease the predawn leaf water potential when increase the root damage.
Autoecology of sweet-chestnut stands in Catalonia (Spain)
Authors: Rubio A. , Elena R. , Sanchez O. , Blanco A. , Sanchez F. , Gomez V.
Published: May 2024

Optimum and marginal parameter ranges have been established for defining landform, climatic and soil habitat diagrams of chestnut (Castanea sativa Miller) woodstands in Catalonia. Such diagrams show that most of the Catalonian chestnut stands are located on soils developed from igneous rocks, with predominant sandyloamy textures. According to FAO criteria, soils are classified as Cambisols. Although soil water holding capacities are considerably low, it does not occur significant drought stress. Despite their relatively high acidity, soil humus form are forest mull. Moreover, several silvicultural parameters have been calculated. After their correlation with the ecological ones, it is concluded that the best chestnut forest sites are located around 750 m elevation, with 240 mm spring rainfall, 11.5 ºC mean annual temperature, and 20 ºC mean temperature at the hottest month.
Preliminary study of the internal structure of the VI(IV)1 phytoclimatic subtype of Allué (1990). Phytoclimatic applications
Authors: Fernández Cancio A. , Sardinero Roscales S. , Manrique Menéndez E.
Published: May 2024

In this paper we try to establish a preliminary methodology for analyzing vegetation structures included in Allué´s (1990) phytoclimatic subtypes, and their phytoclimatic implications. One of the most geographically extensive subtypes (VI(IV)1) has been chosen, which comprises a considerable number of syntaxa.
Facing the climatic change: the rol of forests and forest products as carbon sinks
Authors: Pardos J. A.
Published: May 2024

The relationship between some signals of a possible climatic change, the increase of the atmospheric levels of gases that origin the greenhouse effect and the declining of forests are briefly dealt with in the introduction. The function of tree stands as sinks of the carbon emissions is showed through summarized data referred to the european continent and an estimation for Spain, together with a reference to the missing sink. The role of forestation of new land and the sequestering of carbon inside the wood products are emphasized.
Diagnosis of genuinity and suitability for Quercus coccifera in Spain
Authors: Cañellas I. , San Miguel A.
Published: May 2024

This paper presents the analysis of phytoclimatic genuinity and suitability for Quercus coccifera L., according to the methodology developed by Allué Andrade. 67 thermopluviometric stations where Quercus coccifera shrubland is the climax vegetation were used for that purpose. The predominant climate of the species belong to the phytoclimatic subtype IV1. The coincidence between hierarchies deriving from geographical distribution and ecological conditions is emphasized. Phytoclimatic preferences of Mediterranean Quercus (Q. ilex, Q. suber and Q. coccifera) show a high degree of complementarity. The aptitude of each climatic station is established regarding the phytoclimatic ambit of kermes oak, and a taxonomic key is presented with the aim of determining the suitability of the species for a concrete locality (climatic station).
Fencing effects on mountain ranges of the Sierra del Segura
Authors: Selva Denia M. , Orozco Bayo E. , Martínez Sánchez J. J. , López Donate J. A.
Published: May 2024

Fencing influence on overgrazed ranges of the Sierra del Segura is studied, over two fenced plots, during three years. An important increment of cover in herbaceous plants of elevated pastoral value, mainly perennial legumes, is observated. Uncovered soil ratio decreased by effect of fencing. Woody species of elevated pastoral value increment their cover. An important increment in floral richness and diversity is produced during the first year after fencing. Appearance species ratio decreased after the first year.
The Importance of legumes in the early stages of plant succesion in a burnt pine forest of Albacete province (Spain)
Authors: Martínez Sánchez J. J. , Herranz J. Mª.
Published: May 2024

The role of legumes in the natural regeneration of a burnt pine forests of Albacete province has been studied, recording their frequency and cover in permanent plots in the course of the first five post-fire years. Comparisons with unburnt control plots showed that fire induced a high appearance of annual legumes during the first two years. Legumes were the predominant plant family regarding species number and cover in the first five post-fire years. Scorpiurus muricatus and Psoralea bituminosa were the most abundant species in the first spring after fire, reaching their peak population size during this period. A remarkable second group of species (Trifolium sp. pl., Ornithopus compressus) showed a maximal population size two years after the fire. The abundance and cover of both species groups decreased drastically between the third and fifth year after fire.
Growth experiment trials. Permanent, temporal and interval plots
Authors: V. Gadow K. , Rojo Alboreca A. , Álvarez González J. G. , Rodríguez Soalleiro R.
Published: May 2024

The paper evaluates three types of temporal design of growth experiments: permanent, temporary and interval. Among the disadvantages of permanent plots are the high costs of the research infrastructure and the long wait for data while temporary plots cannot provide information about the rates of change of state variables. Interval plots, measured twice and spread over a range of growing sites, development stages and silvicultural treatment categories, combine the advantages of the permanent and the temporary designs.
The inventory in management projects for resin production
Authors: Allue M.
Published: May 2024

Official rules and literature concerning the practice of inventories in the management projects or revisions of resin production forests are revised in this paper. Several recommendations on the same subject are also made.
Renewable nature resource management. Migrate game and fishing species
Authors: Montoya Oliver J. M. , Mesón García M.
Published: May 2024

By the economical, social and scientific importance of the study and management of migratory species, an unexplored field in the natural renewable resources management, but really complicated, we propose a new management systems for it based on: • Standing crop make with true data capture. • Future projection of actual situation • Estimate the true number trough data on biological management • Results in capture unite in relation with the density This way to work permit us to have a sustainable management in each place without considering international agreement.
Recent landscape changes in mediterranean forest systems of Spain
Authors: Regato P. , Castejón M. , Tella G. , Giménez S. , Barrera I. , Elena-Rosello R.
Published: May 2024

Partial and preliminary results obtained from a Spanish forest formation dynamics study are presented in this paper. Seven land squares located in different land classes and selected according to a fitoclimatological gradient (Allue, 1990), have been diacronically analyzed using aerial photointerpretation and spatial analysis with G.I.S. techniques. As an overall trend, polarization in forest pattern evolution has been detected: Fragmentation and diversification have occurred in coastal and/or periurban areas, and homogenization and extensification have occurred in inner and remote areas.
Detection of lignocellulolytic enzymatic activities of Chaetomium spp.
Authors: Troya T. , Muñoz-Mingarro D. , Llinares F. , Rodríguez-Borrajo C. , Yuste M. , Rubio F.
Published: May 2024

Soft rot in wood in contact with soil is usually produced by different species of Chaetomium. For this reason, the lignocellulolytic capacities of Chaetomium globosum and Chaetomium erraticum, microflora habitually found in farmland, have been studied considering the following tests: formation of biomass, assimilation of carbohydrates, production of extracellular enzymes, and determination of lignocellulolytic activities (cellulase, xylanase, laccase and manganese peroxidase). The substrates used were: glucose, galactose, mannose, xylan and cellulose. The effect of veratryl alcohol as a possible inductor of lignocellulolytic activity was analysed as well. The combined results prove that both species exert show enzymatic capacity which allows the degradation of the principal components of wood, above all, cellulose and hemicellulose. This capacity is seen to be significantly higher in Chaetomium globosum.
Foliar and edaphic parameters in a Quercus robur stand in Galicia (Spain)
Authors: Rozados Lorenzo M. J. , Silva Pando F. J. , Alonso Santos M. , Ignacio Quinteiro M. F.
Published: May 2024

Soil chemical composition during the active period was described in a oak stand (Quercus robur L.) situated at NW Iberian Peninsula. Leaves chemical composition and pigments were analysed on north and south-faced leaves in order to compare both positions. The parameters considered were: C, N, P, K, Ca, Mg, pH, ammonification and nitrification in soil and specific leaf weight (SLW), N, P, Ca, Mg, K, chlorophylls a and b and carotenoids in leaves. We focused on soil nitrification and ammonification processes to investigate nitrogen dynamic and to identify related factors. Significantly higher SLW was observed in south faced leaves than in north faced ones. There is a general trend in north faced leaves to show higher values of chlorophyll and carotenoids (per weight unit) and chlorophyll (per area unit), and in south-leaves to present higher nutrient concentrations, except phosphorus, and increased chlorophyll a/b. Nevertheless, any significant differences were found. The influence of environmental conditions on the soil was showed out by a decrease in C/N ratio in June and an increase in pH values in November.
Thinning experiment in a Scots pine (Pinus sylvestris L.) natural regeneration stand in the Central range
Authors: Montero González G. , Del Río Gaztelurrutia M. , Ortega Muela C.
Published: May 2024

A thinning experience was carried out in a Scots pine natural regeneration stand in the Central range with a site index of 23, according to the quality curves given by Rojo and Montero (1996). The age of the stand at the beginning of the experience (1971) was 35 years, and 60 years at the last inventory (1996). The statistical design of the trial was a randomised complete block with four treatments and three blocks. One treatment was a control or unthinned (A), and the other three were low thinning with different intensities: light (C), moderate (D) and heavy (E) thinnings. In this work, effects of these treatments on stand yield, mean tree and stand structure are studied. Results showed that with the heaviest thinning the total yield of the stand was a bit lower than in control treatment. This lost in production was imperceptible at early ages, so heavy thinning should be applied when stand is still young. According to these results the heaviest treatment of the trial is near the lower density limit for this species (critical basal area of Assmann). On the other hand, mean tree and stand structure characteristics became more suitable for increasing stand stability when thinning were heavy. The grater the intensity of thinning, the lesser the h/d ratio and the larger the square mean diameter. Moreover, more dominated and dying trees are removed. As conclusion we recommend low heavy thinning in early ages, reducing the intensity with age. Specially in stands of middle and high quality, the first thinning should be early, for instance at 20-25 years.
The influence of climatic factors on the onset of flowering and leafing in poplar clones in Delta del Paraná, Argentina
Authors: Garau A. , Filippini de Delfino S. , Berrondo G.
Published: May 2024

We studied the effect of different climatic factors on the burst of flower and leaf buds of several poplar clones through a multivariate analysis technique. Six Populus deltoides clones of wide cultivation in Argentina were studied and phenological observations were done for six years. Meteorological information were photoperiod, chilling hours (as numer of hours with temperature equal or minor than 7 °C), precipitations and temperature considered as degree-day model. Four threshold temperatures and two start dates were considered. Statistical analysis was performed using univariated and multivariate analysis. Temperature summation, with a threshold temperature of 4 °C, beginning on July 1st was the main factor for the begining of the phenophases. Photoperiod, precipitations and chilling hours were less important. The relative importance of the several climatic factors analyzed is discussed related to the geographic origen of Populus deltoides.
Macro and micronutient foliar concentrations in nine eucalyptus species in northwest Spain
Authors: Español E. , Zas R. , Vega G.
Published: May 2024

Sources of variation in foliar nutrient concentration are studied in a provenances test of nine eucalyptus species (E. badjensis, E. globulus ssp. bicostata, E. cypellocarpa, E. delegatensis, E. fastigata, E. nitens, E. obliqua, E. smithii and E. viminalis) in north-western Spain. Sample plot is on an acid and sandy soil, poor in P and Mg. Parent material is granite. Four foliar samples series were collected in February, April, August and November 1996 from six plants of each provenance and species. Samples were analysed for N, P, K, Ca, Mg, Fe, Cu, Zn and Mn. There are significant differences between species and also, important differences between our results and those reported in other studies (in our test plot there are lower levels of N, P and K and higher levels of Ca and Mg for most of the species studied). Seasonal effects are very important in all nutrients and species. Differences between provenances are not clear and provenances-season interaction is not significant in most of cases.
Typology of Pinus sylvestris L. forests in Spain
Authors: Martínez García F. , Montero G.
Published: May 2024

The wide range of ecological factors such as climate, soils, topography, geographical position that can be found in the Iberian peninsula has produced a high diversity of Pinus sylvestris L. communities. In this paper the Scots pine communities in Spain have been reviewed and the different geobotanical interpretations made by Spanish botanists have been analysed. There is no unanimity on how to classify these forests, and some of them have not been included in geobotanical or phytosociological classification because they have been considered like reforestations in climax areas of the other species.
Forest genetic resources in Spain
Authors: Vallejo R. , Sanchez de Ron D. , De Tuero M. , Alia R.
Published: May 2024

This paper summarize the information available for the characterization of forest genetic resources in Spain, based on the Data Bank of the Nature (Ministry of Environment). The GIS oriented data comprise databases for the description of the environment (climate, soil, ecological classification of Spain), the National Catalogue of Base Material (including seed sources, selected stands and provenance regions of the main forest species), the main threats to forest genetic conservation (forest fires, pest and diseases, etc.) and the description of the different categories of protected areas in Spain. This information can be used to describe the genetic resources of tree forest species, and to implement national strategies of forest resources conservation.
Evaluation of genetic diversity and its use in conservation programmes
Authors: Jiménez P. , Collada C.
Published: May 2024

Intraspecific variation is the requirement for evolution and adaptation of a species to new conditions, since it offers the possibility of different responses to selective forces. The quantification of variability is then highly desirable. For assessing variability, several approaches have been used. Phenotypic characters are easily recordable, but show a strong environmental influence and their genetic control is unclear. Molecular markers allow the direct study of genetic material variation but usually traits without phenotypic value are recorded. Two types of variation can be distinguished: Neutral variability, those traits not influenced by selective forces, and adaptive variation, features with selective value. Neutral genetic diversity is estimated mainly by molecular markers. In the last years several techniques have been developed to study both proteins (products of genes) or DNA (hereditary material). A review of the most commonly used techniques is offered, as well as their main applications. The classic method for the study of adaptive variation are provenance/progeny trials, in which levels of variation and the amount corresponding to genetic variabiltiy are analyzed. The basis is to test different genotypes in the same site, in order to minimize the environmental variation. The knowledge of diversity is a prerrequisite in any conservation programm. It is a component of biodiversity that must be preserved, but, also, it is a useful tool for many aspects, specially for determining what processes are involved in the genetic structure of the target species.
Nutrient deficiencies in three pine species (Pinus sp.) grown in hydroponic culture for one growing season
Authors: Gallegos Pérula V. , Navarro Cerrillo R. M. , Alcántara Vara E.
Published: May 2024

The effects of nutrient deficiencies on three pine species (Pinus pinaster Ait., Pinus pinea L. y Pinus halepensis Mill.) are studied in this work. Seeds were planted in a mixture of peat and perlita. When the seedlings reached an adequate size, they were transplanted to hydroponic culture and grown for 4 months (April - July, 1998). Nutrient solutions lacking N, P, K, and Fe, and a control solution were used. During this period, morphological attributes (height, diameter, needles length, and dry weight of shoot and root) and physiological attributes (chlorophyll and nutrient content of needles) were measured, as well as visual symptoms produced by the nutrient deficiencies. Differences were observed depending on the lacking nutrient and the pine species. Nutrient deficiencies affected morphological and physiological attributes and caused growth decrease and visual symptoms. Nevertheless, these effects reached different importance depending on the lacking nutrient and pine species. For example, Fe deficiency caused the greatest and quickest effects, whereas K deficiency hardly affected. Deficiencies effects were greater in shoot growth than in root growth. P. pinaster was the most affected pine species.
Early testing of resin yield in Pinus pinaster Ait.
Authors: Tadesse W. , Auñón F. J. , Pardos J. A. , Gil L. , Alía R.
Published: May 2024

Micro-chipping was carried out in a clonal bank of Pinus pinaster with 17 clones and 69 ramets and 10 control (non grafted trees) trees. The micro-chipping consisted on the tapping of an area of 2.5 square cm above the graft union, every two weeks. Six tapping were made during the 3 months of the maximum resin yield (June, July and August). A high clonal heritability value (h2 = 0,501) for resin yield was computed. This demonstrates that more than 50 % of clonal resin yield variation is due to genetic factors. Moderately strong correlation was recorded between resin yield of the ortets and their micro-chipped clones (r = 0,63, with " = 0,05) showing the effectiveness of both evaluation methods. The resin yield of clones has been very superior to the production of the control trees. The resin yield has been positively correlated with the total height (r = 0,45, & = 0,01) and with the diameter (r = 0,43, & = 0,01) of the trees.
Growth and Yield Models for Pinus halepensis Mill.
Authors: Montero G. , Cañellas I. , Ruíz-Peinado R.
Published: May 2024

Growth and yield models of silviculture applied to four site indices have been drawn up. The data were obtained in 72 plots, installed in 1965 in man made stands of Pinus halepensis Mill., and inventoried in 1965, 1975, 1980, 1988 y 1999. The site index was defined as the top height at age 80 and models were adjusted using the Richards function, obtaining four site qualities: 20, 17, 14 and 11. Following this, silvicultural production models, including two different thinning regimes, were developed for the two higher site qualities sites, with more productive interest (20 and 17) using a simulation with the Hart-Becking rate. For 11 and 14 site quality, only one moderate thinning regime was developed, bearing in mind their most important protection value.
Cutover effects of the vegetation and soil in a natural forest
Authors: Casermeiro J. , De Petre A. A. , Spahn E. , Valenti R.
Published: May 2024

The disturbance produced on vegetation and soil after selective and total cutover of two sites were evaluated. The working area is located in Bovril, Entre Ríos, Argentina. It belongs to the Espinal Province, Ñandubay District, which has humid temperate climate and clay, compact and waterlogged soil. The woody structure was evaluated by the linear and fringe transecting methods. Each site was analyzed to study the floristic composition and the Sorensen similarity index (Is) was applied. Forage and weeds productivity was determined. The soil variables: total nitrogen, phosphorous, total organic carbon and others were estimated. The DCA design was continued. Dates was compared through ANOVA and Tukey test with SAS statistic siystem. The mean crown coverage for trees was 56,65 % and 38 % in the monte and the renoval. The tree density was 1,814 individuals ha–1 and 1,120 individuals ha–1 for both areas. The mean tree height was 4,10 and 2,9 m in each case. The shrub stratum presented few species and the herbaceous carpet was composed of Poaceae, Ciperaceae and Compositeae and a great diversity of others families of less importance. The annual forage volume was 3,505 and 3,271 kg M.S. ha–1 in both sites. The M.O., total nitrogen, assimilated phosphorous and nitrate reached higher values in forest vegetation soil than in soil lacking forest vegetation. The total removal of natural vegetation in the second gorwth forest produced a substantial alteration in its herbaceous, shrub-like and tree structure and the soil nutritive level.
Analysis of horizontal and vertical structures in a multicohort Pine-Oak ecosystem in north Mexico
Authors: Jiménez J. , Aguirre O. , Kramer H.
Published: May 2024

Knowledge on diverse structural traits in multicohort forests is of paramount importance for developing management plans of natural resources. The aim of this study was to define a protocol to understand the dynamics of trees in a mixed pine-oak ecosystem. The proposed methodology is a combination of global forest ecosystem measurement and the four structural group sample technique. All the information gathered was used to determine the abundance and dominance of tree species. Frequency, diameter and height differentiation index and species mingling index were determined using sampling plots. The above was determined for the population of the tree species defined. To measure the species vertical index, the total height of the individual was used, with a three strata distribution (number of individuals and basal area). This research defines an analysis protocol for vertical and horizontal structures in tree species inside multicohort pine-oak forests.
Forest management and carbon captures: Analytical aspects and policy implications
Authors: Díaz Balteiro L. , Romero C.
Published: May 2024

In the last few years there has been an increasing tendency to consider forest ecosystems as possible sinks of carbon dioxide. In this way, it is attempted to mitigate the dramatic increase of global emissions of this gas in the industrialised countries. This new context implies modifications in basic aspects of the forest management discipline, like the determination of the forest optimal forest rotation, including the new European grants. In this paper, some recent experiences in this direction will be critically reviewed and some new ideas will be considered. With this purpose in mind three cases are studied: one species of short rotation (Populus sp.), another one of medium rotation (Pinus radiata D. Don.) and finally one species of long rotation (Pinus sylvestris L.).
Tropical forests and the emerging CO2 market
Authors: Castro R. , Cordero S.
Published: May 2024

Since the Earth Summit gathered in Rio Janeiro in 1992, more than 180 countries of the world have been negotiating the United Nations Framework Convention on Climate Change including a strategy to reduce the emissions of gases that are thought to contribute to global warming. The Kyoto Protocol (1997) –that was announced recently will be ratified– includes provisions to allow countries where emissions reductions are very costly to meet their reduction targets by buying credits from countries where emissions reductions are cheaper. This strategy is still being debated; moreover, the sixth conference of the parties (COP VI) reached only a partial agreement. Costa Rica has been a pioneer in developing and selling emission reduction credits. Costa Rica’s carbon credits came primarily from two sources. First, converting cultivated fields and pastures into forests and second, from reducing deforestation. In 1996, in an unprecedented transaction, Costa Rica sold its first 200,000 tons of carbon emission reduction credits to Norway for $10 per ton of carbon. In early 1998, however, Costa Rica received no bids when it tried to auction an additional 1,000,000 tons of carbon credits with a floor price of $20 per ton. During the year 2001, other 8 Latin American countries offered credits to the World Bank’s Prototype Carbon Fund at prices between $2.9 and $20 per ton. Carbon trade final results will depend on the ultimate rules, regulations, and carbon prices.
Structure and regeneration patterns of pedunculate oak and European beech in an old-growth lowland forest in Cantabria, Spain
Authors: Rozas V.
Published: May 2024

The composition and structure of four stands of old-growth forest located in the Cantabrian lowlands, were described. The regeneration patterns of the dominant tree species as well as their relationships with the forest history were analysed. Age distributions and canopy history were reconstructed by using dendroecological techniques, and the spatial dimension of tree regeneration was studied by quantitative spatial analysis. The forest under study is composed of two dominant tree species, Fagus sylvatica L. and Quercus robur L., along with a shade-tolerant understory tree (Ilex aquifolium L.) and a group of five pioneer species. Both dominant species showed balanced populations, with monotonic-descendent or compound diameter distributions. All tree populations under study comprised two cohorts: young trees 20-70 years old and mature trees 155-260 years old. Both cohorts were separated by a period of 100-140 years lacking regeneration. F. sylvatica and Q. robur establishment showed a significant clumped pattern, with a significant repulsion from adult trees at a small spatial scale. The recruitment of Q. robur took place mainly in open space and canopy gaps, while the main limiting factor for F. sylvatica regeneration was the presence of mature trees of their own species. Tree establishment along the 20th century started in the 1930s, coinciding with a disturbance period, a reduction in forest density, and a decrease in grazing intensity.
Structure and spatial variability of Pinus uncinata Ram. growth forms at two contrasting treeline ecotones in the Spanish Pyrenees
Authors: Camarero J. J. , Gutierrez E.
Published: May 2024

We describe the spatial distribution of Pinus uncinata individuals classified according to their growth-form and size at two undisturbed altitudinal treeline ecotones in the Spanish Pyrenees (Ordesa, O; Tessó, T). At each site, a rectangular plot (30 ´140 m) was located with its longest side along the altitudinal gradient, and encompassing treeline and timberline. At both sites, living individuals were bigger and had a higher number of needle cohorts downslope. The distribution of size and growth-form classes at site O followed a neat sequence of increasing size downslope, from abundant shrubby multi-stemmed krummholz individuals with few needle cohorts (1-3) up to bigger uni-stemmed arborescent trees with several needle cohorts (4-12). In contrast, structural changes through the ecotone at site T were gradual, and they did not follow so neatly this sequence of increasing size downslope.
Preliminary site index model and individual-tree growth and mortality models for black pine (Pinus nigra Arn.) in Catalonia (Spain)
Authors: Palahí M. , Grau J. M.
Published: May 2024

A site index model, a distance-independent individual-tree diameter growth model, a static height model and a mortality model for Pinus nigra Arn. in Catalonia were preliminarily developed based on 2 to 7 measurements of 6 permanent sample plots established in 1964 by the Instituto Nacional de Investigaciones Agrarias (INIA). The plots ranged in site index from 9 to 15 m (dominant height at 60 years). The data for the diameter growth model consisted of 2997 observations and ranged in age from 45 to 132 years. The data for the height and mortality models consisted of 1065 and 3044 observations, respectively. A polymorphic difference equation derived from the Hossfeld function was selected to model dominant height development. This dynamic equation can compute predictions directly from any age-dominant height pair without compromising consistency of the predictions. The predictions of dynamic equations are unaffected by arbitrary changes in base-age. The relative bias for the diameter g rowth model and the height model were –0.80 and 0.13 %, respectively. The relative RMSE values for the diameter growth and height model were 67.7, 8.93 %, respectively. A logistic model for the probability of a tree to survive the coming 5-year period was prepared. The model set enables the simulation of stand development on an individual tree basis an accurately described the long-term development of sample plots of the study.
Estimation of crown diameter from the normal diameter (d1,3) in Casuarina equisetifolia Forst. plantations
Authors: Benitez Naranjo J. Y. , Rivero Vega M. , Vidal Corona A. , Rodríguez Rodríguez J. , Álvarez Rivera R. C.
Published: May 2024

In this work a mathematical model is obtained from a sample of 301 Casuarina equisetifolia Forst trees, which permits the determination of the average diameter crown from the normal diameter (d 1. 30). The measurements of 215 trees were used to perform the regression analysis and to validate the selected equation the corresponding measurements of 86 trees were taken. This study was done in the serpentinous savanna of Camagüey province plantations, located in Las Cuabas, Camagüey Silvicultural Unit belonging to Camagüey Forestry Integrated Enterprise. Three mathematical models were compared, being the linear model the most appropriate to perform the average crown diameter estimation. This model results in easy practical management.
Afforestations and its relationships with soil erosion and productivity in forest-steppe transition (Andinopatagonia, Argentina)
Authors: Broquen P. , Falbo G. , Apcarián A. , Candan F. , Girardin J. , Pellegrini V.
Published: May 2024

In Andinopatagonian region —Neuquén province— forested areas for wood production, located in forest – steppe ecotone, have increased during the last decades, where one of the most serious environmental problems is desertification caused by over-grazing. This turn critical other functions of afforestations such as soil conservation. A regional simulation of forest land use and its effect on soil erosion was done. Erosion under forest was estimated and compared with actual erosion, on soil cartographic units from moderately to very apt. Potential forest control on erosion was evident in the cartographic units under steppe vegetation. Field erosion and its consequences on potential productivity was estimated and compared under Pinus ponderosa Dougl. —first stand from 14 to 19 years old— and under shrub gramineous steppe. Eleven paired plots were selected in representative sites of the cartographic units, distributed from west to east, each pair under each vegetation type with equivalent physiographic conditions. A-horizon depth was higher under pine than under steppe, which indicated soil losses under steppe about 136 t-1 ha-1 year. This determined a decrease on Site Index at 14 years between 0.53 and 0.43 m, which implied a decline on potential productivity of the ecosystem. Soil losses under steppe in relation to soil losses under afforestations evidenced forest effect on erosion control and sustainable productivity uphold. This has a temporal projection and its consideration is decisive for ecosystem management.
Analysis of diameter distributions and conservation of forests of northern Morocco
Authors: Ajbilou R. , Marañón T. , Arroyo J.
Published: May 2024

The analysis of diameter distributions for different tree populations in a forest, allows to evaluate its ecological and conservation conditions. In particular, this type of analysis allows to detect a lack of regeneration or an ageing trend. A total of 84 samples of native forests have been studied in the Tingitanian Peninsula, northern Morocco. Forests of Quercus suber and Q. canariensis tend to have an assimetric, positive diameter distribution; this pattern reflects a lack of regeneration. Forests of Cedrus atlantica have a great proportion of small-diameter trees, indicating a recovering stage after past massive logging. Forests of Pinus pinaster var. maghrebiana have a relative higher number of trees within the intermediate size classes, indicating an ageing trend. Sacred forests or morabitos are usually dominated by large, old trees of Quercus suber ; in some cases, tree-sized Quercus coccifera and Phillyrea latifolia are dominant.
The role of Ulmus laevis in German floodplain landscapes
Authors: Mackenthun G. L.
Published: May 2024

In the past, the spread of modern civilisation has heavily reduced the occurrence of natural woodlands in floodplain landscapes and the numbers of elms have also been reduced on a large scale. At the time of the outbreak of Dutch elm disease (DED), the elm populations may have already been reduced by an estimated 90%. At that time, Ulmus minor was the most common elm species in the riparian forests of lowland Central Europe. Eighty years later, the numbers of U. minor had decreased significantly. Data from three rivers in Saxony, Germany suggest that a further 90% of the trees have succumbed to DED. The survivors have mostly been reduced to shrubs and small trees. Ulmus laevis has taken over the role of the typical and well established elm species in floodplain landscapes. Being less susceptible to DED, the trees dominate parts of floodplain meadow landscapes and riparian forests. However, the overall number is low when compared with other tree species. Most U. laevis trees find only restricted habitats within agricultural landscapes and in many cases the elm itself is the only reminder of the existence of a former riparian wildwood. Also, some individuals show a high degree of crown transparency without having been infected with DED. If elms are to constitute an important part of the floodplain tree flora in the future, it is crucial to protect and enhance the existing U. laevis populations. Controlled provenances can help in the process of re-establishing floodplain forests.
Ultrastructure of the alveolar network and its relation to coating on vessel walls in elms infected by Ophiostoma novo-ulmi and in other plants affected with similar wilt diseases
Authors: Ouellette G. B. , Rioux D. , Simard M. , Chamberland H. , Cherif M. , Baayen R. P.
Published: May 2024

In elms infected with Dutch elm disease, alveolar networks, demarcated by filamentous-like bands and confluent with similar matter (the coating) accumulating on vessel walls, occurred regularly in vessel elements. Similar material lined vessel walls in inoculated, sterilized, thin elm wood sections fixed by high pressure freezing. The coating was observed to connect with fungal cells and occasionally contained small opaque particles, the size of ribosomes, membranous and vesicular structures, and, following incubation of wood chips taken from diseased samples incubated on an agar medium, it still displayed similar matter. Coating and alveolar bands increased in thickness by confluence of other bands or membranous structures. Similar matter and structures also occurred in other plants affected by similar fungal wilt diseases. In all systems, the compact coating did not label for chitin, cellulose and pectin. In staghorn sumac, the probe for DNA attached to the coating. Altogether, in the light of these data, it appears that the coating and alveolar networks are not inert components, a fact which indicates their primordial probable pathogen origin. It is proposed that these elements might be important not only in the initial infection stages but also in older or recurrent infections at a time when host resistance mechanisms are ineffective.
Elm forests in North Bulgaria and conservation strategies
Authors: Stoyanov N.
Published: May 2024

From the genus Ulmus, the naturally spread species in Bulgaria are Ulmus minor, U. laevis, and U. glabra. The main reason for the decreasing of the number and density of the elm populations in Bulgaria are the epyphytonic expressions of the Dutch elm disease (DED) in the 1920s and 1970s, after which the representatives of genus Ulmus today occur predominantly as solitaire trees, biogroups and rarely form stands. In connection with the preservation of the genepool of the elms after the in situ method, an inventory of their genetic resources in North Bulgaria has started in 2002. To study the variability according to morphological signs and health status 17 permanent sample plots have been established and 60 plus trees have been determined. For the needs of the afforestation six seed stands were established. The ex situ conservation method was carried out through clone collections, progeny trials and experimental plantations.
Oasification: a forest solution to many problems of desertification
Authors: Martínez de Azagra A. , Mongil J. , Rojo L.
Published: May 2024

Desertification is a widespread process worldwide, particularly acute on deforested sloping lands under arid, semiarid or dry sub-humid conditions. To counteract this environmental threat, we have opted for an approach promoting the opposite process, which has been termed oasification. It entails the building of small earth structures to collect and infiltrate as much precipitation and runoff as possible by modifying a slope’s physiography in a convenient and non-aggressive manner. As a result, better soil moisture conditions will prevail and the chances of the establishment and growth of woody vegetation will be markedly improved, thus redressing the dangerous process of desertification. Since ancient times, many water harvesting strategies (microcatchments, ridging, terracing, etc.) have been successfully employed to check, collect and infiltrate surface runoff in those regions of the world where precipitation is scarce. All these structures can be currently designed according to enlightened hydrologic criteria based on sound knowledge of water economy, water requirements, soil erosion, building costs and landscape impacts. These criteria should help land managers and technicians in deciding the appropriate planting densities and micropond sizes that will yield the best seedling survival rates with minimal disturbance to the original physiography of the slope.
Effects of canopy history and climate on radial growth patterns of Fagus sylvatica L. and Quercus robur L.
Authors: Rozas V.
Published: May 2024

Radial growth patterns and the effects of canopy history and climate on the growth of beech (Fagus sylvatica L.) and oak (Quercus robur L.) in a mature forest in the Cantabrian lowlands, were studied. Tree ages ranged between 150 to 270 years, and their diameters were of up to 86 cm in beech and 129 cm in oak. The most frequent growth pattern in beech showed a conspicuous rising trend since 1900 to nowadays. This pattern was a consequence of disturbances that occurred in 1929, 1956 y 1978, which accounted for a significant increment in beech growth rates above those expected from random observations. On the other hand, oak growth was only slightly affected by canopy history. The most abundant growth patterns were negative exponential or monotonic descendent, which could be expected for oak in the absence of disturbances. Also, only 26% of the radial growth patterns of oak showed disturbance signals. The climate variability accounted for 28.4% of beech’s ring-width variation and 26.7% of oak’s one. Precipitation in July showed a positive effect on oak radial growth, while beech growth was negatively related to temperature in June-July. These results suggested the feasible effects of climate warming on the productivity of natural forests.
A volume prediction system for Quercus robur L. in Galicia (Northwestern Spain) based on a volume ratio equation
Authors: Barrio Anta M. , Álvarez González J. G. , Díaz-Maroto Hidalgo I. J.
Published: May 2024

Eight total-volume equations and four volume-ratio equations (for diameter limits) were fitted to a sample of 225 trees of Quercus robur of different ages. The trees were collected in stands growing in a great variety of site qualities and densities in Galicia (Northwest of Spain). The data employed to develop volume ratio equations have a longitudinal structure so a second order autoregressive model was used to correct the error dependence implicit in this kind of data. Several «goodness-of-fit» statistics were used in order to select the best equations within each group (total volume equations and volume ratio equations) and cross-validation was used to analyse the performance of the model. Finally, the models selected were combined to develop a volume equation with product classification.