Ecuaciones de volumen total y comercial para rebrotes de salix babylonica var. Sacramenta `Soveny Americano ́

Las ecuaciones de volumen son una herramienta eficaz para la estimación del volumen del árbol individual, información que es esencial para la planificación y la gestión de rodales forestales. El objetivo de este trabajo fue ajustar ecuaciones de volumen total y comercial con corteza para rebrotes del clon Salix babylonica var. sacramenta `Soveny Americano´ (también conocido como sauce americano). Se trabajó con árboles provenientes de rebrotes de plantaciones establecidas inicialmente con alta densidad (1680 árboles/ha). Se ajustaron 3 ecuaciones de volumen mediante regresión lineal y no lineal que fueron analizadas estadística y gráficamente. Además, los modelos se ajustaron teniendo en cuenta una función de varianza (modelos generalizados). Se seleccionó el modelo de Schumacher y Hall para la estimación del volumen total con corteza y el modelo de Spurr (variable combinada) para la estimación de volumen útil (comercial). El rango de aplicación del modelo de volumen total es de 6,9 cm a 35 cm de diámetro a la altura del pecho (7,1 m hasta 20,7 m de altura total), mientras que el rango para el modelo de volumen comercial es de 8 cm a 35 cm (8,8 m hasta 20,7 m de altura). El error medio obtenido para el modelo de volumen total resultó -0,2% para el volumen total y - 1,2% para el volumen comercial, mientras que el error absoluto promedio fue 10,1% (0,016 m3) y 12,2% (0,015 m 3) para el volumen total y comercial, respectivamente.EEA Delta del ParanáFil: Fernandez Tschieder, Ezequiel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales. Cátedra de Silvicultura; ArgentinaFil: Achinelli, Fabio Germán. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales. Cátedra de Silvicultura; ArgentinaFil: Russo, Federico. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales. Cátedra de Silvicultura; ArgentinaFil: Angelinetti, S. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales. Cátedra de Silvicultura; Argentin

La forestación de salicáceas como aporte al desarrollo sustentable del Delta del Paraná

La producción forestal en los humedales del Delta del Paraná se basa principalmente en el cultivo de Populus (álamos) y Salix (sauces para producción de madera y sauces mimbre), ambos géneros pertenecientes a la familia Salicáceas. Con algunas diferencias en sus características de cultivo y requerimientos ambientales, estos géneros forestales poseen tradición en el territorio debido a su excelente y variada aptitud industrial, desde “triturado”, que comprende la elaboración de pulpa para papel y de tableros de partículas, a los “usos sólidos” (aserrado, debobinado, vigas, muebles, entre otros). En la disertación se darán a conocer cómo y en qué los agentes de desarrollo de la EEA Delta del Paraná –INTA- aportan al crecimiento del sector foresto-industrial de la región. El trabajo se aborda mediante una red multidisciplinaria que se ocupa de la conservación de los recursos naturales, protección vegetal, ecofisiología, silvicultura, mejoramiento genético, aspectos socioeconómicos y la extensión. Asimismo, se presentarán resultados recientes sobre clones mejorados de álamos y sauces, de aplicación en el Delta. En el caso del sauce, que ocupa el 98% de las plantaciones del delta entrerriano, se cuenta con clones recientemente seleccionados por INTA dotados de alta tolerancia al anegamiento prolongado. Se exponen conceptos vinculados a la selección y al potencial de los materiales mejorados de rápido crecimiento, adaptados a zonas inundables, y aptos para diversos usos industriales.EEA Delta del ParanáFil: Cerrillo, Teresa. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Alvarez, Javier Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Alvarez, Jorge Lisandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Battistella, Agustín. Ministerio de Agricultura Ganadería y Pesca. Dirección de Producción Forestal; ArgentinaFil: Braccini, Celina Laura. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Casaubon, Edgardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Cortizo, Silvia Cora. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Fernandez, Patricia Carina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Ceballos, Dario Sebastian. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Fernandez Tschieder, Ezequiel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Faustino, Laura Ines. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Fracassi, Natalia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Garcia Cortes, Manuel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: González, Adrián. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Grieco, Leda. Fundación ArgenInstituto Nacional de Tecnología Agropecuaria (INTA). Programa de Capacitación Gratuita para Estudiantes Universitarios; ArgentinaFil: Hemming, Juan Agustin. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Landi, Lucas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Mangieri, Victor. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Mema, Vanesa Yamila. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Monteverde, María Silvana. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; Argentina. Universidad de Concepción del Uruguay. Facultad de Ciencias Agrarias Universidad de Concepción del Uruguay. Cátedra de Genética y Mejoramiento; ArgentinaFil: Mujica, Gerardo Oscar. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Olemberg, Demián Jeremí­as. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; Argentin

From trees to stands: production ecology, growth dominance and carbon partitioning

2021 Fall.Includes bibliographical references.Growth of a stand is the sum of the growth of individual trees, and it can be distributed among trees proportional to their size or a group of trees may produce a disproportional share of the stand's growth. Large trees within a stand usually have higher growth rates than smaller trees. The production ecology of trees shows that this is the result of large trees' greater resource acquisition, and greater efficiency of wood production per unit of resource used. However, the fact that large trees grow faster than small trees does not necessarily imply that these trees produce a disproportional share of the stand growth. The distribution of a stand's growth among trees is influenced by how trees compete for resources (symmetric or asymmetric competition) and by the efficiency with which trees used those resources to grow. This dissertation had two main questions: (1) how growth distribution relates to patterns of competition and patterns of resource use efficiency with tree size (Chapter I, II and III), and (2) why large trees have greater resource use efficiency for wood production than small trees within a stand (Chapter IV). In the first chapter, I proposed a specific connection between production ecology of trees and growth dominance patterns. Growth dominance is a measure of how the growth of a stand is distributed among trees. It can be negative or positive whether small or large trees account for a greater proportion of stand growth than its contribution to stand biomass, or null if all trees contribute a similar proportion to the growth and biomass of a stand (Figure 1). Specifically, positive growth dominance should relate to asymmetric competition for resources and (or) to increasing resource use efficiency with tree size in a stand. Null growth dominance should result from symmetric competition for resources and similar resource use efficiency among trees in a stand. Reverse growth dominance should arise from symmetric competition for resources and (or) from a decreasing resource use efficiency with tree size in a stand. In the second chapter, I used a Pinus ponderosa stand undergoing strong negative growth dominance (growth dominance negative = −0.22) to test the corresponding pattern proposed in Chapter I. Dominant trees were 5-times larger than suppressed trees but captured a less-than-proportional amount of light relative to their size compared with suppressed trees (90.4 vs. 20.9 GJ year-1 tree-1) and light use efficiency declined with tree size. Suppressed trees were twice as efficient as dominant trees (0.11 vs. 0.05 kg[wood] GJ [PAR]-1). In the third chapter, I studied the relationship between growth dominance and production ecology across species including conifer and broadleaf. Both light competition and patterns of resource use efficiency with tree size explained a large portion of the variation in the distribution of growth across tree sizes. Growth dominance increased with the asymmetry of competition for light (i.e., growth dominance increased as larger trees increased their share of light interception) and as light use efficiency increased with tree size. In the fourth chapter, I analyzed the pattern of water use efficiency across trees in eucalyptus experimental plots. I hypothesized that differences in water use efficiency related to changes in carbon partitioning between trees. Specifically, dominant trees should partition less photosynthate belowground than smaller trees, resulting in greater wood growth per unit of resource used. I combined tree transpiration and integrated crown water use efficiency to estimate tree-scale gross primary production, and belowground fluxes were estimated by subtracting aboveground production and respiration from gross primary production. Dominant trees produced 2.3-times more wood per unit of water transpired (0.87 vs. 0.38 gC LH2O-1), fixed 1.1-more carbon per unit of water transpired (3.4 vs. 3 gC LH2O-1) and partitioned 2.2-times more carbon to wood production than suppressed trees (0.26 vs 0.12). Belowground partitioning decreased with tree size; however, the uncertainty in transpiration measurements showed that this pattern might be the result of the underestimation of gross primary production in dominant trees. Overall, this study indicated that growth distribution (growth dominance) and production ecology patterns were related, but in variable ways. Stands with asymmetric distributions of growth are likely to have greater asymmetries in resource interception and resource use efficiency among trees. Variation in resource use efficiency related to both photosynthetic efficiency of trees and carbon partitioning to wood. However, the evidence supporting lower belowground carbon partitioning by dominant trees needs to be corroborated with future tests

Linking competition with Growth Dominance and production ecology

The development of forests over time is influenced by competition for resources among trees, leading to patterns of size hierarchy. These two aspects – competition and size hierarchy – can be examined in conjunction with a production ecology perspective. Competition for resources between individuals has often been represented as a continuum between absolute symmetry and absolute asymmetry. Symmetric competition implies that trees capture resources proportional to size, whereas asymmetric competition implies that large trees capture a disproportional share of contested resources over small trees. Furthermore, the competitive ability of a tree is also determined by the efficiency with which the resources are used to grow. Competition is often inferred indirectly from size inequality or size hierarchy of the size structure using the Gini coefficient. This approach assumes that the predominant mode of competition is asymmetric, and that size hierarchy reflects a degree of competition. This presumption is not always valid, and in this case size hierarchy does not reliably represent competition. A more insightful examination of competition might be interpreted from the Growth Dominance approach. Growth dominance summarizes the growth distribution in relation to size structure, and characterizes how effectively large trees dominate growth in a population. When competition is not asymmetric, size hierarchy does not imply a hierarchy on growth relative to size. For example, two stands experiencing opposite modes of competition could have the same Gini coefficient, but will show different Growth Dominance coefficients. We propose that the connection between competition and Growth Dominance relates to specific resource use and resource use efficiency patterns among trees in a stand. Growth dominance can be positive (if larger trees dominate growth), null (if no particular group of trees dominate growth) or reverse (if smaller trees dominate growth). Positive Growth Dominance should relate to asymmetric competition for resources and (or) to increasing resource use efficiency with tree size in a stand. Null Growth Dominance should result from symmetric competition for resources and similar resource use efficiency among trees in a stand. Reverse Growth Dominance should arise from symmetric competition for resources and (or) from a decreasing resource use efficiency with tree size in a stand. We look forward to the development of many case studies that will challenge our idea, either refining or refuting it.EEA Delta del ParanáFil: Fernandez Tschieder, Ezequiel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; Argentina. Colorado State University. Department of Ecosystem Science and Sustainability. Graduate Degree Program in Ecology; Estados UnidosFil: Binkley, Dan. Northern Arizona University. School of Forestry; Estados Unido

Production ecology and reverse growth dominance in an old-growth ponderosa pine forest

The growth of a stand is the sum of the growth of individual trees. Growth of individual trees can be explained by the amount of resources captured and how efficiently those resources are used (production ecology). The relationship between the contribution of a tree to stand growth relative to the contribution to stand biomass is expressed by the growth dominance. Patterns of growth dominance vary among tree species and stand age, suggesting that differences in production ecology underlie the observed patterns of growth dominance within stands. We explored the production ecology in an old-growth ponderosa pine forest. Growth dominance was strongly negative (−0.22) and was the outcome of a less-than-proportional increase of tree growth as a function of tree size. Dominant trees were almost 5 times larger than suppressed trees (1024 vs. 211 kg tree−1) but grew only about 2 times more than suppressed trees (4.3 vs. 1.9 kg tree−1 year−1). Dominant trees captured a lessthan-proportional amount of light relative to their size (90.4 vs. 20.9 GJ year−1 tree−1) and light use efficiency declined with tree size. Suppressed trees were twice as efficient as dominant trees (0.11 vs. 0.05 kg[wood] GJ [PAR]−1). Our results highlight the link between growth dominance, competition for resources, and the pattern of light use efficiency among large versus small trees.EEA Delta del ParanáFil: Fernandez Tschieder, Ezequiel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; Argentina. Colorado State University. Department of Ecosystem Science and Sustainability. Graduate Degree Program in Ecology; Estados UnidosFil: Binkley, Dan. Northern Arizona University. School of Forestry; Estados UnidosFil: Bauerle, William. Colorado State University. Department of Horticulture and Landscape Architecture; Estados Unido

Why do Pinus species have different growth dominance patterns than Eucalyptus species? A hypothesis based on differential physiological plasticity

It has been observed that Eucalyptus stands show high growth dominance levels while Pinus stands show null or low growth dominance levels. We hypothesized that this differential behaviour is linked to a higher degree of physiological–biochemical plasticity in Eucalyptus than in Pinus species related to photosynthetic capacity. This leads to an increment in growth efficiency (GE) difference between the largest and the smallest trees of a stand, and therefore to high growth dominance levels in Eucalyptus. To test our hypothesis we carried out a bibliographical survey and reanalyzed data from Pinus ponderosa and Pinus taeda plantations in Argentina. We found that some species within the genus Eucalyptus present higher growth dominance levels, physiological plasticity and GE differentiation than Pinus species. The mean maximum values of these traits reported for any Eucalyptus species were: growth dominance coefficient, 0.48; photosynthetic capacity increment when resource availability increases, 175%; GE difference between the largest and the smallest trees of a stand, 300%. Mean maximum values for the same traits reported for any Pinus species were 0.13, no phostosynthetic plasticity as the most frequent pattern, and 51%, respectively. In Pinus species the most frequent response to an increase in resource availability is characterized by an increase in leaf area or biomass, maintaining a similar photosynthetic capacity per unit area. However, it appears that in P. ponderosa there are some situations, characterized by a high degree of intraspecific competition, leading to a very high degree of GE differentiation which deserve future research. Although we did not find any study reporting simultaneously all variables concerning our hypothesis (growth dominance, growth efficiency differentiation and physiological plasticity) any of the circumstantial evidence found in the bibliography contrasts our hypothesis.EEA BarilocheFil: Fernandez, Marí­a Elena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Fernandez Tschieder, Ezequiel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Letourneau, Federico Jorge. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Campo Forestal General San Martín; ArgentinaFil: Gyenge, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; Argentin

Ecuación de volumen total para Populus deltoides de plantaciones del Bajo Delta del Paraná

Las ecuaciones de volumen son una herramienta eficaz para la estimación del volumen del árbol individual, información que es esencial para la planificación y la gestión de rodales forestales. Las ecuaciones de volumen para Populus spp. (álamo) en el Delta del Paraná son escasas y no existen para clones ampliamente difundidos en la actualidad. El objetivo de este trabajo fue ajustar una ecuación estándar de volumen total, con y sin corteza, para los clones ‘Australiano 129/60’ y ‘Australiano 106/60’ de Populus deltoides. Se trabajó con árboles de plantaciones localizadas en campos protegidos contra las inundaciones por diques perimetrales de la región Islas del Río Carabelas. Se evaluó la capacidad de predicción de ecuaciones de volumen publicadas para la especie y se ajustaron seis ecuaciones de volumen, mediante técnicas de regresión lineal y no lineal ponderada, que fueron analizadas estadística y gráficamente. La estimación del volumen de los clones “australianos” a partir de modelos publicados resultó poco precisa. Todas las ecuaciones ajustadas presentaron muy buenos estadísticos de ajuste. Se seleccionó el modelo de Schumacher y Hall para la estimación del volumen total con y sin corteza. El rango de aplicación de los modelos va desde 11,1 cm hasta 55,1 cm de diámetro a 1,3 m de altura y desde 11,9 m hasta 37,5 m de altura total. El error medio obtenido en la autovalidación resultó -1,2% (0,001 m3) para el volumen total con corteza y -1,3% (0,000 m3) para el volumen total sin corteza, mientras que el error absoluto promedio fue 6,8% (0,041 m3) y 6,6% (0,034 m3) para el volumen total con y sin corteza, respectivamente.Volume equations are a useful tool for individual tree volume estimate, which is essential information for forest stand planning and management. Volume equations for poplar in the delta of the Paraná River are scarce and do not exist for very widespread clones currently. The purpose of this work was to fit a standard total volume equation outside and inside bark for the clones ‘Australiano 129/60’ and ‘Australiano 106/60’ of Populus deltoides. The trees were sampled in plantations protected against floods by a dike located in the region Carabelas River Island. The prediction capacity of published volume equations for the species was evaluated and six volume equations were fitted by weighted linear and no linear regression, which were analyzed statistically and graphically. The “australianos” clones volume estimate from published equations resulted inaccurate. All the equations presented very good fit statistics. The Schumacher and Hall model was selected for the estimate of the total outside and inside bark volume. The models applicability ranges from 11.1 to 55.1 cm in diameter at 1.3 m height and from 11.9 to 37.5 m in total height. The average error obtained at the self-validation was -1.2% (0.001 m3) to the outside bark volume and -1.3% (0.000 m3) to the inside bark volume, while the average absolute error was 6.8% (0.041 m3) and 6.6% (0.034 m3) to the outside bark and inside bark volume respectively.EEA Delta del ParanáFil: Fernandez Tschieder, Ezequiel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Fassola, Hugo Enrique. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Montecarlo; ArgentinaFil: Garcia Cortes, Manuel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; Argentin

Populus deltoides ‘Australiano 129/60’: variación axial de la densidad y desarrollo de un modelo predictivo de la densidad del árbol completo = Populus deltoides clone 'Australian 129-60’: density axial variation and predictive model for whole tree density

Los objetivos de este trabajo fueron determinar la variación axial de la densidad de la madera de Populus deltoides ‘Australiano 129/60’ y desarrollar un modelo predictivo de la densidad total del árbol a partir de la densidad a una única altura. Se voltearon 11 árboles de 10 años de tres clases diamétricas en Buenos Aires, Argentina. Se extrajeron muestras a siete alturas del fuste (0,5 m; 0,7 m; 1,0 m; 2,2 m; 6,6 m; 11,0 m y 15,4 m). Se determinó la densidad normal media y media ponderada por volumen al 15% de contenido de humedad. Se realizaron ANOVAs entre alturas de muestreo y clases diamétricas. Se realizaron regresiones lineales y no lineales, simples y múltiples, para ajustar modelos de predicción de la densidad media ponderada del fuste, tomando como variables predictoras la densidad normal a 1 m de altura y el diámetro a la altura del pecho. La densidad media fue de 458 ± 35 kg m–3 y la densidad ponderada de 470 ± 14 kg m–3. La variación axial mostró un aumento significativo de los valores de densidad desde la base hacia el ápice. La densidad tomada a 1,0 m subestimó la densidad ponderada del árbol completo en un 11%. Se verificó una mayor densidad en las clases diamétricas superiores. Se considera factible producir estos álamos con mayores diámetros y obtener al mismo tiempo mayor densidad. Es posible ajustar modelos de estimación de la densidad media ponderada a partir de una muestra tomada a una única altura y el DAP.The aims were to determine the axial variation pattern for wood density of Populus deltoides clone ‘Australian 129-60’ and to develop a predictive model for whole tree density from density at one sample height. Eleven ten-year-old trees from three diametric classes were sampled in Buenos Aires Province, Argentine. Disks were taken at seven sampling heights (0.5 m; 0.7 m; 1.0 m; 2.2 m; 6.6 m; 11.0 m and 15.4 m). Density and weighted density were determined at 15% of moisture content. An analysis of variance was carried out for sampling heights and diametric classes. The relationship between whole tree density and predictive parameters, density at 1.0 m height and Diameter at breast height (DBH), was quantified using linear and non linear regression analyses. Clone mean density was 458± 35 kg m–3 and weighted density was 470 ± 14 kg m–3. Density axial variation shows significantly increasing values from the lower sampling height to the top. Density taken at breast height, approximately (1.0 m), underestimates (11%) the weighted density of whole tree. It is feasible to produce high diameters poplars and to obtain major wood density at the same time. It is possible to fit models to estimate the mean weighted density of whole tree based on density at breast height approximately, with linear regression analysis.EEA Delta del ParanáFil: Diaz, Gastón. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; ArgentinaFil: Monteoliva, Silvia Estela. Universidad Nacional de La Plata. Facultad de Ciencias Agrarias y Forestales; ArgentinaFil: Alvarez, Javier Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Fernández Tschieder, Ezequiel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; Argentin

Influence of growth dominance and individual tree growth efficiency on Pinus taeda stand growth. A contribution to the debate about why stands productivity declines

A well recognized pattern during even-aged stands development is the growth decline after reaching a peak. We studied the effect of changes in stand structure, characterized by growth dominance, upon stand growth, stand growth efficiency and tree growth efficiency in thinned and unthinned plots of Pinus taeda. According to the stated hypothesis (Binkley, 2004), stand growth decline would be related to a decrease in growth efficiency of smaller trees due to the increase of growth dominance. Growth dominance in unthinned plots continuously increased with age, although it was very low compared to other genus, particularly Eucalyptus. In thinned plots, growth dominance was even lower and no consistent trend through time was observed. In general large trees were more efficient than small trees in unthinned and thinned plots, however, growth efficiency of both, small and large trees, showed the same pattern with age. Nevertheless, in both treatments, the difference between growth efficiency of smallest and largest trees increased with developing growth dominance because the increasing difference in tree size with age. At stand level lower growth dominance levels did not result in higher stand growth efficiency. Based on the low growth dominance levels, we cannot conclude that increasing growth dominance during stand development can be responsible for its growth decline. Growth dominance appears not to be the cause but the consequence of growth efficiency differentiation between small and large trees of a stand.EEA Delta del ParanáFil: Fernandez Tschieder, Ezequiel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Delta del Paraná; ArgentinaFil: Fernandez, María Elena. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Schlichter, Tomas Miguel. Instituto Nacional de Tecnología Agropecuaria (INTA). Dirección Nacional; ArgentinaFil: Pinazo, Martin Alcides. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Montecarlo; ArgentinaFil: Crechi, Ernesto Hector. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Montecarlo; Argentin