Analyzing size-symmetric vs. size-asymmetric and intra-vs. inter-specific competition in beech (Fagus sylvatica L.) mixed stands

In mixed stands, inter-specific competition can be lower than intra-specific competition when niche complementarity and/or facilitation between species prevail. These positive interactions can take place at belowground and/or aboveground levels. Belowground competition tends to be size symmetric while the aboveground competition is usually for light and almost always size-asymmetric. Interactions between forest tree species can be explored analyzing growth at tree level by comparing intra and inter-specific competition. At the same time, possible causes of niche complementarity can be inferred relating intra and inter-specific competition with the mode of competition, i.e. size-symmetric or sizeasymmetric. The aim of this paper is to further our understanding of the interactions between species and to detect possible causes of competition reduction in mixed stands of beech (Fagus sylvatica L.) with other species: pine?beech, oak?beech and fir?beech. To test whether species growth is better explained by size-symmetric and/or size-asymmetric competition, five different competition structures where included in basal area growth models fitted using data from the Spanish National Forest Inventory for the Pyrenees. These models considered either size-symmetry only (Reineke?s stand density index, SDI), size-asymmetry only (SDI of large trees or SDI of small trees), or both combined. In order to assess the influence of the admixture, these indices were introduced in two different ways, one of which was to consider that trees of all species compete in a similar way, and the other was to split the stand density indices into intra- and inter-specific competition components. The results showed that in pine?beech mixtures, there is a slightly negative effect of beech on pine basal area growth while beech benefitted from the admixture of Scots pine; this positive effect being greater as the proportion of pine trees in larger size classes increases. In oak?beech mixtures, beech growth was also positively influenced by the presence of oaks that were larger than the beech trees. The growth of oak, however, decreased when the proportion of beech in SDI increased, although the presence of beech in larger size classes promoted oak growth. Finally, in fir?beech mixtures, neither fir nor beech basal area growth were influenced by the presence of the other species. The results indicate that size-asymmetric is stronger than size-symmetric competition in these mixtures, highlighting the importance of light in competition. Positive species interactions in size-asymmetric competition involved a reduction of asymmetry in tree size-growth relationships.

Metodología para la estimación de indicadores armonizados a partir de los inventarios forestales nacionales europeos con especial énfasis en la biodiversidad forestal

Durante las últimas décadas el objetivo principal de la silvicultura y la gestión forestal en Europa ha pasado de ser la producción de madera a ser la gestión sostenible de los ecosistemas, por lo que se deben considerar todos los bienes y servicios que proporcionan los bosques. En consecuencia, es necesario contar con información forestal periódica de diversos indicadores forestales a nivel europeo para apoyar el desarrollo y la implementación de políticas medioambientales y que se realice una gestión adecuada. Para ello, se requiere un seguimiento intensivo sobre el estado de los bosques, por lo que los Inventarios Forestales Nacionales (IFN), (principal fuente de información forestal a gran escala), han aumentado el número de variables muestreadas para cumplir con los crecientes requerimientos de información. Sin embargo, las estimaciones proporcionadas por los diferentes países no son fácilmente comparables debido a las diferencias en las definiciones, los diseños de muestreo, las variables medidas y los protocolos de medición. Por esto, la armonización de los datos que proporcionan los diferentes países es fundamental para la contar con una información forestal sólida y fiable en la Unión europea (UE). La presente tesis tiene dos objetivos principales: (i) establecer el diseño de una metodología para evaluar la biodiversidad forestal en el marco del Inventario forestal nacional de España teniendo en cuenta las diferentes iniciativas nacionales e internacionales, con el objetivo de producir estimaciones comparables con las de otros países de la UE y (ii) armonizar los indicadores más relevantes para satisfacer los requerimientos nacionales e internacionales. Como consecuencia del estudio realizado para alcanzar el primer objetivo, la metodología diseñada para estimar la biodiversidad fue adoptada por el Tercer Inventario forestal nacional. Ésta se componía de indicadores agrupados en: cobertura del suelo, composición de árboles y especies de arbustos, riqueza de especies herbáceas y helechos, especies amenazadas, estructura, madera muerta, y líquenes epífitos. Tras el análisis del diseño metodológico y de los datos proporcionados, se observó la conveniencia de modificarla con el fin de optimizar los costes, viabilidad, calidad y cantidad de los datos registrados. En consecuencia, en el Cuarto Inventario Forestal Nacional se aplica una metodología modificada, puesto que se eliminó el muestreo de especies herbáceas y helechos, de líquenes epífitos y de especies amenazadas, se modificaron los protocolos de la toma de datos de estructura y madera muerta y se añadió el muestreo de especies invasoras, edad, ramoneo y grado de naturalidad de la masa. En lo que se refiere al segundo objetivo, se ha avanzado en la armonización de tres grupos de variables considerados como relevantes en el marco de los IFN: los indicadores de vegetación no arbórea (que juegan un papel relevante en los ecosistemas, es donde existe la mayor diversidad de plantas y hasta ahora no se conocían los datos muestreados en los IFN), la determinación de los árboles añosos (que tienen un importante papel como nicho ecológico y su identificación es especialmente relevante para la evaluación de la biodiversidad forestal) y el bosque disponible para el suministro de madera (indicador básico de los requerimientos internacionales de información forestal). Se llevó a cabo un estudio completo de la posible armonización de los indicadores de la vegetación no arbórea en los IFN. Para ello, se identificaron y analizaron las diferentes definiciones y diseños de muestreo empleados por los IFN, se establecieron definiciones de referencia y se propusieron y analizaron dos indicadores que pudiesen ser armonizados: MSC (mean species cover) que corresponde a la media de la fracción de cabida cubierta de cada especie por tipo de bosque y MTC (mean total cover). Se estableció una nueva metodología que permite identificar los árboles añosos con los datos proporcionados por los inventarios forestales nacionales con el objetivo de proporcionar una herramienta eficaz para facilitar la gestión forestal considerando la diversidad de los sistemas forestales. Se analizó el concepto de "bosque disponible para el suministro de madera" (FAWS) estudiando la consistencia de la información internacional disponible con el fin de armonizar su estimación y de proporcionar recomendaciones para satisfacer los requerimientos europeos. Como resultado, se elaboró una nueva definición de referencia de FAWS (que será adoptada por el proceso paneuropeo) y se analiza el impacto de la adopción de esta nueva definición en siete países europeos. El trabajo realizado en esta tesis, puede facilitar el suministrar y/o armonizar parcial o totalmente casi la mitad de los indicadores de información forestal solicitados por los requerimientos internacionales (47%). De éstos, prácticamente un 85% tienen relación con los datos inventariados empleando la metodología propuesta para la estimación de la biodiversidad forestal, y el resto, con el establecimiento de la definición de bosque disponible para el suministro de madera. No obstante, y pese a que esta tesis supone un avance importante, queda patente que las necesidades de información forestal son cambiantes y es imprescindible continuar el proceso de armonización de los IFN europeos. ABSTRACT Over the last few decades, the objectives on forestry and forest management in Europe have shifted from being primarily focused on wood production to sustainable ecosystem management, which should consider all the goods and services provided by the forest. Therefore, there is a continued need for forest indicators and assessments at EU level to support the development and implementation of a number of European environmental policies and to conduct a proper forest management. To address these questions, intensive monitoring on the status of forests is required. Therefore, the scope of National Forest Inventories (NFIs), (primary source of data for national and large-area assessments), has been broadened to include new variables to meet these increasing information requirements. However, estimates produced by different countries are not easily comparable because of differences in NFI definitions, plot configurations, measured variables, and measurement protocols. As consequence, harmonizing data produced at national level is essential for the production of sound EU forest information. The present thesis has two main aims: (i) to establish a methodology design to assess forest biodiversity in the frame of the Spanish National Forest Inventory taking into account the different national and international initiatives with the intention to produce comparable estimates with other EU countries and (ii) to harmonize relevant indicators for national and international requirements. In consequence of the work done related to the first objective, the established methodology to estimate forest biodiversity was adopted and launched under the Third National Forest Inventory. It was composed of indicators grouped into: cover, woody species composition, richness of herbaceous species and ferns, endangered species, stand structure, dead wood, and epiphytic lichens. This methodology was analyzed considering the provided data, time costs, feasibility, and requirements. Consequently, in the ongoing Fourth National Forest Inventory a modified methodology is applied: sampling of herbaceous species and ferns, epiphytic lichens and endangered species were removed, protocols regarding structure and deadwood were modified, and sampling of invasive species, age, browsing impact and naturalness were added. As regards the second objective, progress has been made in harmonizing three groups of variables considered relevant in the context of IFN: Indicators of non-tree vegetation (which play an important role in forest ecosystems, it is where the highest diversity of plants occur and so far the related sampled data in NFIs were not known), the identification of old-growth trees (which have an important role as ecological niche and its identification is especially relevant for the assessment of forest biodiversity) and the available forest for wood supply (basic indicator of international forestry information requirements). A complete analysis of ground vegetation harmonization possibilities within NFIs frame was carried on by identifying and analyzing the different definitions and sampling techniques used by NFIs, providing reference definitions related to ground vegetation and proposing and analyzing two ground vegetation harmonized indicators: “Mean species cover” (MSC) and “Mean total cover” (MTC) for shrubs by European forest categories. A new methodology based on NFI data was established with the aim to provide an efficient tool for policy makers to estimate the number of old-growth trees and thus to be able to perform the analysis of the effect of forest management on the diversity associated to forest systems. The concept of “forest available for wood supply” (FAWS) was discussed and clarified, analyzing the consistency of the available international information on FAWS in order to provide recommendations for data harmonization at European level regarding National Forest Inventories (NFIs). As a result, a new reference definition of FAWS was provided (which will be adopted in the pan-European process) and the consequences of the use of this new definition in seven European countries are analyzed. The studies carried on in this thesis, can facilitate the supply and/or harmonization partially or fully of almost half of the forest indicators (47%) needed for international requirements. Of these, nearly 85% are related to inventoried data using the proposed methodology for the estimation of forest biodiversity, and the rest, with the establishment of the definition of forest available for wood supply. However, despite this thesis imply an important development, forest information needs are changing and it is imperative to continue the process of harmonization of European NFIs.

O uso do eucalipto em sistemas silvipastoril: acúmulo de fitomassa arbórea e de pastagem

O presente estudo foi dividido em três capitulos, todos realizados na Estação Experimental de Ciências Florestais de Anhembi/SP, entre os anos de 2014 e 2015. O primeiro estudo intitulado de \"Variação mensal da fitomassa da forragem em função do grau de cobertura do dossel em sistemas silvipastoris\", foi realizado em 3 monoculturas de 13 anos de idade, com área útil de 50 m x 30 m para coleta de pasto as mesmas efectuadas mensalmente. Os resultados apresentaram que não há relação significativa entre a cobertura do dossel e fitomassa da forragem pelo caso de que o sub-bosque estava muito sombreado. Entretanto, houve uma relação indireta entre área basal e fitomassa. Evidenciando-se que o talhão de Eucalipto urograndis apresentou as melhores condições de crescimento e disponibilidade de materia seca mensal para Bachiaria decumbens além de obter a maior porcentagem de folha entre todos os tratamentos. Ao contrario, no talhão de Pinus tecunumanii, foi encontrada a menor disponibilidade de materia seca mensal e por consequência, menor porcentagem de folha. O segundo estudo foi chamado de: \"Disponibilidade de fitomassa de B. decumbens, em um sistema silvipastoril com eucalipto: o papel da radiação\" onde o componente florestal foi o eucalyptus (COP-1377) de 2 anos de idade plantado em uma área útil de 10 ha, dividido em 3 tratamentos (onda longa-OL (39 m), onda curta-OC (21 m), e testemunha-T) e instalado em 4 blocos distintos. Foram realizadas duas coletas dutante o período de verão e de inverno, onde foi possível verificar que o tratamento OL mostrou maior disponibilidade de fitomassa a 65% de irradiância além de obter maior porcentagem da fração folha. Este foi favorecido pelo maior espaçamento entre as aléias. Contudo, houve ataque de cigarinha na pastagem, mantendo a queda da disponibilidade no período de inverno. O terceiro estudo intitulado de: \"Variaçoes arquiteturais de uma monocultura de E. urograndis em função de sua posição espacial\", foi também realizado na monocultura do primeiro estudo, numa área de 7 ha. Para este estudo, realizou-se um inventario florestal, logo após, dividiu-se as árvores por sua classe diamétrica e selecionou-se aleatoriamente 60 árvores para cubagem, e destas, escolheu-se 15 para determinação da fitomassa e respectiva densidade da madeira. Para a obtenção da fitomassa dividiu-se as árvores em três frações de análise: tronco, galhos e folha. Além disso, as 15 árvores foram divididas em: bordadura, intermediária e centro da parcela, de acordo com a sua localização. Verificou-se que a bordadura apresentou os maiores crescimentos em DAP, altura, largura de copa e, que por consequência, obteve maior volume e fitomassa em todas suas frações. Também foi possível observar que tanto a bordadura quanto o centro apresentaram maior densidade básica em função da maior copa e altura das árvores incentivando a geração de mais fitomassa foliar. Finalmente conforme os três estudos realizados neste trabalho de pesquisa, concluiu-se que a radiação solar é fator chave na produtividade da cultura forrageira, demonstrando a necessidade de mais pesquisas sobre os sistemas agroforestais e silvipastoris para o sucesso de futuros emprendimentos.

Assessment of a Biomass Utilization Alternative for Colorado State Parks

Colorado State Parks is currently managing overstocked wildland fuels on critical Parklands through mechanical mastication projects, but wants to determine the feasibility of alternatively turning thinned materials into marketable biomass fuel. Accurate estimates of potential volume and associated production costs are critical to determining this feasibility. In this study, forest inventory data were used to estimate potential volume and combined with data from previous studies to estimate potential harvest and haul costs and revenues. This study reveals that a biomass utilization alternative may be an economically feasible option for State Parks to pursue and in many cases may be more economically favorable than current mechanical treatments.

Permanent open water surfaces in central Siberia from ENVISAT ASAR wide swath data 2003/2004, link to shapefile

Permanent water bodies not only store dissolved CO2 but are essential for the maintenance of wetlands in their proximity. From the viewpoint of greenhouse gas (GHG) accounting wetland functions comprise sequestration of carbon under anaerobic conditions and methane release. The investigated area in central Siberia covers boreal and sub-arctic environments. Small inundated basins are abundant on the sub-arctic Taymir lowlands but also in parts of severe boreal climate where permafrost ice content is high and feature important freshwater ecosystems. Satellite radar imagery (ENVISAT ScanSAR), acquired in summer 2003 and 2004, has been used to derive open water surfaces with 150 m resolution, covering an area of approximately 3 Mkm**2. The open water surface maps were derived using a simple threshold-based classification method. The results were assessed with Russian forest inventory data, which includes detailed information about water bodies. The resulting classification has been further used to estimate the extent of tundra wetlands and to determine their importance for methane emissions. Tundra wetlands cover 7% (400,000 km**2) of the study region and methane emissions from hydromorphic soils are estimated to be 45,000 t/d for the Taymir peninsula.

Wetlands in central Siberia from ASAR WS 2003, link to shapefiles

An area in central Siberia (partial coverage of Turukhansky und Yeniseysky districts) was investigated using satellite data. It covers freshwater ecosystems of non-forested peatlands in boreal forests. The satellite data represent the growing seasons of 2003/2004. Microwave data were acquired by the Advanced Synthetic Aperture Radar (ASAR) instrument onboard ENVISAT. The multi-temporal capabilities and resolution (150mx150m in WS mode) of the ASAR wide swath mode enabled the detection of dynamic features >2ha over this vast area. Scatterometer (QuikScat) data could be employed to distinguish hydro-periods. Wetland types have been identified on the basis of seasonal changes in backscatter. Results for peatlands have been compared with Russian forest inventory data which contain information on wetland distribution.

Pollen from 50 lake surface samples in Brandenburg, Germany, in 2009

Past changes in plant and landscape diversity can be evaluated through pollen analysis, however, pollen based diversity indexes are potentially biased by differential pollen production and deposition. Studies examining the relationship between pollen and landscape diversity are therefore needed. The aim of this study is to evaluate how different pollen based indexes capture aspects of landscape diversity. Pollen counts were obtained from surface samples of 50 small to medium sized lakes in Brandenburg (Northeast Germany) and compiled into two sets, with one containing all pollen counts from terrestrial plants and the second restricted to wind-pollinated taxa. Both sets were adjusted for the pollen production/dispersal bias using the REVEALS model. A high resolution biotope map was used to extract the density of total biotopes and different biotopes per area as parameters describing landscape diversity. In addition tree species diversity was obtained from forest inventory data. The Shannon index and the number of taxa in a sample of 10 pollen grains are highly correlated and provide a useful measure of pollen type diversity which corresponds best to landscape diversity within one km of the lake and the proportion of non-forested area within seven km. Adjustments of the pollen production/dispersal bias only slightly improve the relationships between pollen diversity and landscape diversity for the restricted dataset as well as for the forest inventory data and corresponding pollen types. Using rarefaction analysis, we propose the following convention: pollen type diversity is represented by the number of types in a small sample (low count e.g. 10), pollen type richness is the number of types in a large sample (high count e.g. 500) and pollen sample evenness is characterized by the ratio of the two. Synthesis. Pollen type diversity is a robust index that captures vegetation structure and landscape diversity. It is ideally suited for between site comparisons as it does not require high pollen counts. In concert with pollen type richness and evenness, it helps evaluating the effect of climate change and human land use on vegetation structure on long timescales.

Epidometria de Calophyllum brasiliense Camb. em plantios comerciais

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Florestal, Programa de Pós-Graduação em Ciências Florestais, 2016.

Dinâmica de uma floresta tropical manejada na Amazônia oriental

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Florestal, 2016.

Umbrella pine above ground biomass estimation with very high spatial resolution satellite images

Above ground biomass is frequently estimated with forest inventory data and an extrapolation method for the per unit area evaluations. This procedure is labour demanding and costly. In this study above ground biomass functions, whose independent variable is crown horizontal projection, were developed. Multi-resolution segmentation method and object-oriented classification, based on very high spatial resolution satellite images, were used to obtain the area of tree crown horizontal projection for umbrella pine (Pinus pinea L.). A set of inventory plots were measured and with existing allometric functions for this species above ground biomass per tree and per plot were calculated. The two data sets were used to fit linear functions both for individual plot and their cumulative values. The results show a good performance of the models. Errors smaller than 10% are obtained for stand areas greater than 1.4 ha. These functions have the advantages of estimating above ground biomass for all the area under study or surveillance, not requiring forest inventory; allow monitoring in short time periods; and are easily implemented in a geographical information system environment.

Above ground biomass estimation in Mediterranean multiple use systems with high spatial resolution satellite images

Forest biomass has been having an increasing importance in the world economy and in the evaluation of the forests development and monitoring. It was identified as a global strategic reserve, due to its applications in bioenergy, bioproduct development and issues related to reducing greenhouse gas emissions. The estimation of above ground biomass is frequently done with allometric functions per species with plot inventory data. An adequate sampling design and intensity for an error threshold is required. The estimation per unit area is done using an extrapolation method. This procedure is labour demanding and costly. The mail goal of this study is the development of allometric functions for the estimation of above ground biomass with ground cover as independent variable, for forest areas of holm aok (Quercus rotundifolia), cork oak (Quercus suber) and umbrella pine (Pinus pinea) in multiple use systems. Ground cover per species was derived from crown horizontal projection obtained by processing high resolution satellite images, orthorectified, geometrically and atmospheric corrected, with multi-resolution segmentation method and object oriented classification. Forest inventory data were used to estimate plot above ground biomass with published allometric functions at tree level. The developed functions were fitted for monospecies stands and for multispecies stands of Quercus rotundifolia and Quercus suber, and Quercus suber and Pinus pinea. The stand composition was considered adding dummy variables to distinguish monospecies from multispecies stands. The models showed a good performance. Noteworthy is that the dummy variables, reflecting the differences between species, originated improvements in the models. Significant differences were found for above ground biomass estimation with the functions with and without the dummy variables. An error threshold of 10% corresponds to stand areas of about 40 ha. This method enables the overall area evaluation, not requiring extrapolation procedures, for the three species, which occur frequently in multispecies stands.

Above ground biomass functions with vegetation indices for multiple use systems of two evergreen oaks

Remote sensing is a promising approach for above ground biomass estimation, as forest parameters can be obtained indirectly. The analysis in space and time is quite straight forward due to the flexibility of the method to determine forest crown parameters with remote sensing. It can be used to evaluate and monitoring for example the development of a forest area in time and the impact of disturbances, such as silvicultural practices or deforestation. The vegetation indices, which condense data in a quantitative numeric manner, have been used to estimate several forest parameters, such as the volume, basal area and above ground biomass. The objective of this study was the development of allometric functions to estimate above ground biomass using vegetation indices as independent variables. The vegetation indices used were the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Simple Ratio (SR) and Soil-Adjusted Vegetation Index (SAVI). QuickBird satellite data, with 0.70 m of spatial resolution, was orthorectified, geometrically and atmospheric corrected, and the digital number were converted to top of atmosphere reflectance (ToA). Forest inventory data and published allometric functions at tree level were used to estimate above ground biomass per plot. Linear functions were fitted for the monospecies and multispecies stands of two evergreen oaks (Quercus suber and Quercus rotundifolia) in multiple use systems, montados. The allometric above ground biomass functions were fitted considering the mean and the median of each vegetation index per grid as independent variable. Species composition as a dummy variable was also considered as an independent variable. The linear functions with better performance are those with mean NDVI or mean SR as independent variable. Noteworthy is that the two better functions for monospecies cork oak stands have median NDVI or median SR as independent variable. When species composition dummy variables are included in the function (with stepwise regression) the best model has median NDVI as independent variable. The vegetation indices with the worse model performance were EVI and SAVI.

A structured inventory of spiders (Arachnida, Araneae) in natural and artificial forest gaps at Porto Urucu, Western Brazilian Amazonia

A preliminary survey of the spider fauna in natural and artificial forest gap formations at “Porto Urucu”, a petroleum/natural gas production facility in the Urucu river basin, Coari, Amazonas, Brazil is presented. Sampling was conducted both occasionally and using a protocol composed of a suite of techniques: beating trays (32 samples), nocturnal manual samplings (48), sweeping nets (16), Winkler extractors (24), and pitfall traps (120). A total of 4201 spiders, belonging to 43 families and 393 morphospecies, were collected during the dry season, in July, 2003. Excluding the occasional samples, the observed richness was 357 species. In a performance test of seven species richness estimators, the Incidence Based Coverage Estimator (ICE) was the best fit estimator, with 639 estimated species. To evaluate differences in species richness associated with natural and artificial gaps, samples from between the center of the gaps up to 300 meters inside the adjacent forest matrix were compared through the inspection of the confidence intervals of individual-based rarefaction curves for each treatment. The observed species richness was significantly higher in natural gaps combined with adjacent forest than in the artificial gaps combined with adjacent forest. Moreover, a community similarity analysis between the fauna collected under both treatments demonstrated that there were considerable differences in species composition. The significantly higher abundance of Lycosidae in artificial gap forest is explained by the presence of herbaceous vegetation in the gaps themselves. Ctenidae was significantly more abundant in the natural gap forest, probable due to the increase of shelter availability provided by the fallen trees in the gaps themselves. Both families are identified as potential indicators of environmental change related to the establishment or recovery of artificial gaps in the study area.

New, low estimate for carbon stock in global forest vegetation based on inventory data

Abstract