Biomasa aérea en ecosistemas de Prosopis pallida (Humb. and Bonpl. ex Willd.) H. B. K. usando imágenes Landsat 7 ETM+

The significance of field work in remote sensing studies when applied to large areas has often been underestimated. The combination of specific forest inventories for the estimation of aboveground biomass in large dry tropical forest areas with remote sensor data has scarcely been explored to date. In this work, a systematic, stratified forest inventory involving 100 × 100 m square plots in an area of Peruvian Prosopis pallida dry forest, roughly one million hectares in size in the Piura province (Peru) has been compiled. The inventory encompassed the principal silvicultural variables defining the ecosystem studied, which were used in allometric equations for the different species, genera and plant associations in the area in order to estimate the amount of aboveground biomass present in each plot. Field data were related to a Landsat 7 ETM+ image by using six different vegetation indices derived from an image mosaic for the area. Two regression equations (relating the amount of aboveground phytomass to the different vegetation indices) provided reasonably acceptable phytomass predictions for the type of ecosystem concerned (R2 between 0.72 and 0.52).La importancia del trabajo de campo en estudios de teledetección radica en la necesidad de proveer una validación a los valores de reflectividad incluidos en los datos de los sensores remotos. La diversidad ecológica del medio forestal y la evaluación de grandes superficies de difícil acceso hacen de la combinación del inventario forestal y de la teledetección una herramienta compleja y útil en el análisis del medio terrestre. El presente trabajo muestra la aplicación de un inventario sistemático estratificado sobre un millón de hectáreas de bosque tropical seco de Prosopis pallida en el Departamento de Piura (Perú) en la validación de diferentes tipos de clasificación realizadas sobre dicho ecosistema mediante el uso de imágenes Landsat ETM+. El inventario recoge las principales variables del ecosistema y de los individuos, tomadas en parcelas de 1 hectárea, que posteriormente fueron relacionadas con los valores de reflectividad de las imágenes mediante el uso de índices de vegetación. Se hallaron ecuaciones de regresión entre valores de fracción de suelo cubierto y cinco índices de vegetación, obteniéndose resultados con R2 de hasta 72 %. Los niveles de significación hallados mediante el uso de los índices NDVI y EVI permiten una estimación razonable del estado del bosque seco de Prosopis pallida del Departamento de Piura de una forma económica, fácil de repetir en el tiempo y aplicable a zonas que difícilmente pueden ser evaluadas mediante inventarios convencionales

Contrasting Response to Drought and Climate of Planted and Natural Pinus pinaster Aiton Forests in Southern Spain

Extreme drought events and increasing aridity are leading to forest decline and tree mortality, particularly in populations near the limits of the species distribution. Therefore, a better understanding of the growth response to drought and climate change could show the vulnerability of forests and enable predictions of future dieback. In this study, we used a dendrochronological approach to assess the response to drought in natural and planted forests of the maritime pine (Pinus pinaster Aiton) located in its southernmost distribution (south of Spain). In addition, we investigated how environmental variables (climatic and site conditions) and structural factors drive radial growth along the biogeographic and ecological gradients. Our results showed contrasting growth responses to drought of natural and planted stands, but these differences were not significant after repeated drought periods. Additionally, we found differences in the climate–growth relationships when comparing more inland sites (wet previous winter and late spring precipitation) and sites located closer to the coast (early spring precipitation). Response functions emphasized the negative effect of defoliation and drought, expressed as the June standard precipitation-evapotranspiration index calculated for the 12-month temporal scale and the mean temperature in the current February, on growth. The strong relationship between climatic variables and growth enabled acceptable results to be obtained in a modeling approach. The study and characterization of this tree species’ response to drought will help to improve the adaptive management of forests under climate change

Analysis of Site-dependent Pinus halepensis Mill. Defoliation Caused by ‘Candidatus Phytoplasma pini’ through Shape Selection in Landsat Time Series

High levels of ‘Candidatus Phytoplasma pini’ have produced extensive forest mortality on Pinus halepensis Mill forests in eastern Spain. This has led to the widespread levels of forest mortality. We used archival Landsat imagery and shapes algorithm implemented in the Google Earth Engine to explore the potential of the LandTrendr algorithm and its outputs, together with field observations, to analyze and predict the health status in P. halepensis stands affected by ‘Candidatus Phytoplasma pini’ in Andalusia (south-eastern Spain). We found that the Landsat time series algorithm (LandTrendr) has captured both long- and short-duration trends and changes in spectral reflectance related to phytoplasma disturbance in the Aleppo pine forest stands investigated. The normalized burn ratio (NBR) trends were positively associated with environmental variables: Annual precipitation, mean temperature, soil depth, percent base saturation and aspect. Environmental variables were tested for their contributions to the mapping of changes in Aleppo pine cover in the study area, as an empirical modeling approach to disturbance mapping in forests of south-eastern Spain. The methodology outlined in this paper has produced valuable results that indicate new possibilities for the use in forest management of remote-sensing technologies based on spectral trajectories associated with pest-diseases defoliation. Given the likely increase in pest risks in the forests of southern Europe, accurate assessment and map of pest outbreaks on forests will become increasingly important, both for research and for practical applications in forest management

Estimación de la biomasa área de ecosistemas de matorral en el sur de España

Although forest biomass estimates are vital for estimating carbon fluxes, the database for estimating the biomass or carbon pool in Mediterranean shrub ecosystems is lacking. This paper reports the above-ground phytomass estimates obtained for shrub ecosystems in Southern Spain. The phytomass values obtained were 1143 g m–2 for heath, 447 g m–2 for rock rose thicket-heath, 788 g m–2 for rock rose thicket and 1404 g m–2 for gorse thicket formations; the corresponding values for bushes were 695 g m–2 for mancha phytomass and 1966 g m–2 for Pistacia lentiscus formations. The photosynthetic-to-total phytomass ratio ranged from 0.156 for mancha highbush to 0.213 in rock rose thickets, with a mean value of 0.187 for the study ecosystems as a whole. The estimates of sequestered carbon differed between the shrub-type ecosystems in the interval between 2.23 t ha–1 for Cistus ladanifer to 9.83 t ha–1 for Pistacia lentiscus. A better understanding of biomass in Mediterranean shrub communities will provide useful information on the growth pattern of these species, biomass mapping, remote sensing and regional estimations of primary productivity in these areas.La estimación de biomasa en ecosistemas forestales es un parámetro crucial para el cálculo del ciclo de carbono. Sin embargo, la información disponible para estos ecosistemas sigue siendo insuficiente. En este artículo se presentan los resultados del cálculo de biomasa aérea de algunos ecosistemas de matorral en el sur de España (Montes de Propios-Jerez de la Frontera, Cadiz). Los valores de biomasa aérea obtenidos han sido de 1143 g m–2 en brezales, 447 g m–2 en jarales-brezales, 788 g m–2 en jarales puros, 1404 g m–2 en aulagares, 695 g m–2 para mancha, y 1966 g m–2 para lentiscales. El valor de la relación biomasa fotosintética-biomasa área total vario entre 0,156 para mancha y 0,213 para jarales, con un valor medio de 0,187 para el conjunto de formaciones estudiadas. El carbono retenido en estos ecosistemas oscila en el intervalo entre 2,23 t ha–1 para Cistus ladanifer y 9,83 t ha–1 para lentiscares. Una información mas precisa sobre la biomasa de los ecosistemas de matorral puede suponer una ayuda muy importante para la interpretación de la dinámica de estos ecosistemas y la aplicación de nuevas herramientas para su estimación en grandes superficies

Estudio de una superfamilia de genes de respuesta a patógenos (repat) en insectos

El intestino de los insectos es una de las principales vías de entrada de entomopatógenos. Con el fin de minimizar los efectos negativos de los patógenos, el intestino de los insectos posee diferentes mecanismos: síntesis de péptidos antimicrobianos, producción de especies reactivas de oxígeno, activación de los sistemas de reparación y detoxificación, melanización, fagocitosis, apoptosis y la renovación celular, entre otros. Estudios de expresión tras la exposición a diferentes patógenos han mostrado cómo la expresión de ciertos genes varía en el intestino tras la infección. Previamente a la realización de esta tesis, se identificó, en el lepidóptero Spodoptera exigua, una familia de genes que aumentaba sus niveles de expresión en el intestino tras la exposición a la toxina Cry1Ca de Bacillus thuringiensis y a baculovirus. Esta familia, compuesta por cuatro miembros en su inicio, se denominó repat (por respuesta a patógenos). Al comienzo de esta tesis no se disponía de información sobre el papel de estos genes en la respuesta a patógenos. Es por ello que el objetivo principal de esta tesis ha consistido en profundizar en el conocimiento sobre la familia REPAT, tanto en el estudio de su función a nivel molecular como en determinar sus implicaciones en la respuesta del intestino de los insectos a distintos microorganismos entomopatógenos y sus factores de virulencia. En un primer capítulo, la comparación a nivel transcripcional entre una población de S. exigua susceptible y otra resistente, a un producto comercial basado en B. thuringiensis (XentariTM), mostró una elevada expresión constitutiva de cuatro genes repat en la población resistente. Tres de estos genes repat eran nuevos, se secuenciaron y se nombraron como repat5, repat6 y repat7. Además, se observó una correlación positiva entre la expresión de repat5 y la resistencia al producto XentariTM. En un segundo capítulo tratamos de aproximarnos a la función molecular de estos genes a través del estudio de las proteínas que interaccionan con REPAT1 mediante la técnica del doble híbrido. Para ello se construyó una genoteca que contiene los genes que se expresan en el intestino de larvas de quinto estadio de S. exigua. En los experimentos de doble híbrido en levaduras se observó que dos proteínas interaccionaban con REPAT1. Estas proteínas eran REPAT4 y una nueva proteína similar a ésta, que se secuenció y se nombró como REPAT8. En estudios de localización celular se observó que REPAT1 se encuentra en el citoplasma celular, pero en presencia de REPAT8 aparece también en el núcleo. El análisis de la expresión de los ocho genes descritos hasta el momento mostraron una respuesta general a los tratamientos relacionados con B. thuringiensis (toxina Cry1Ca, XentariTM y una cepa de B. thuringiensis que no produce toxinas Cry, Bt cry-) y no frente a otros tratamientos con bacterias no patógenas (Escherichia coli, Enterococcus spp. y otras presentes en su microbiota), sugiriendo que la expresión de estos genes se activa principalmente en respuesta al daño celular. En un tercer capítulo, aprovechando la reciente secuenciación del transcriptoma de S. exigua por parte de nuestro grupo, tratamos de identificar nuevos genes repat. El análisis del trancriptoma reveló la presencia de al menos 46 miembros diferentes. El análisis de estas secuencias mostró la presencia de ciertos motivos conservados, así como la posible clasificación de sus miembros en dos grandes clases: αREPATs y βREPATs. Además, en este capítulo estudiamos la expresión de esta superfamilia de genes, observando un cambio en la expresión en intestino de los αrepats tras la intoxicación con Cry1Ca pero no en respuesta a un aumento de la microbiota en el intestino de las larvas. Interesantemente, al estudiar la expresión de estos genes en las células madre del intestino (en comparación a la expresión en el intestino completo), las larvas con mayor carga bacteriana mostraron un mayor número de genes repat expresados en estas células madre. El aumento del número de genes repat en S. exigua ha permitido la identificación de homólogos en otras especies de insectos: Spodoptera frugiperda, Spodoptera littoralis, Spodoptera litura, Mamestra configurata, Mamestra brassicae, Helicoverpa armigera, Bombyx mori y en el díptero Drosophila melanogaster. En el organismo modelo D. melanogaster se identificaron dos homólogos: CG13323 y CG13324. Dado que en Drosophila existen herramientas moleculares no disponibles para S. exigua, se decidió estudiar la función de estos homólogos para profundizar en el conocimiento de estos genes. Para ello se obtuvo, tanto un mutante con la deleción de CG13323 y CG13324, como mutantes de sobreexpresión de CG13323. El mutante con ambos genes delecionados mostró un aumento en la supervivencia a la infección con Pseudomonas entomophila, lo cual resultó contrario al resultado esperado, ya que los genes han mostrado aumento de su expresión después de la infección. También se observó un aumento en la supervivencia, tanto de larvas como de adultos, en los mutantes que sobreexpresan CG13323. Para comprobar si CG13323 estaba implicado en alguna de las rutas del sistema inmune de D. melanogaster, se estudió la expresión de algunos genes marcadores (diptericina de la ruta Imd, upd3 de la ruta JAK-STAT y vein de la ruta EGF), no encontrándose ningún cambio relacionado con la sobreexpresión de CG13323 que nos permitiera situar los genes repat en algunas de las principales rutas del sistema inmune de insectos. Debido a las características de los genes repat y las proteínas que codifican: la gran cantidad miembros de la misma familia, su diferente respuesta a nivel de expresión, el pequeño tamaño de las proteínas, la interacción entre miembros de la misma familia que produce su translocación nuclear, y la homología de alguno de sus miembros a factores transcripcionales como es MBF2, sugieren la posibilidad de que diferentes combinaciones de proteínas REPAT podrían ser responsables de la regulación de la transcripción de genes implicados en distintos aspectos de la fisiología del insecto.The insect gut is one of the main routes of entrance of entomopathogens. In order to minimize the negative effects from pathogens, insect gut possesses several mechanisms: synthesis of antimicrobial peptides, production of reactive oxygen species, activation of repair and detoxification systems, melanization, phagocytosis, apoptosis and cell renewal, among others. Expression analysis has shown differences in the transcription profile of certain genes in the insect gut due to the exposure to different pathogens. Prior to the start of this thesis, a family of genes was identified in the lepidopteran Spodoptera exigua by their increased expression in midgut after exposure to Cry1Ca toxin from Bacillus thuringiensis and to baculovirus infection. This family, initially composed by four members, was named REPAT (in REsponse to PAThogens). At the beginning of this thesis, no information about the molecular function of this new family of genes was available. With the current thesis we plan to increase our knowledge about the REPAT family and its implications in the insect gut response to entomopathogenic microorganisms and their virulence factors. In the first chapter, comparing the gene expression profiles of B. thuringiensis-resistant and susceptible colonies of S. exigua, four repat genes showed a higher constitutive expression in the resistant population. Three of these repat genes were novel and they were sequenced and named as repat5, repat6 and repat7. Moreover, a positive correlation was observed between the expression of repat5 and the resistance to the XentariTM product. In a second chapter we advanced to the molecular function of these genes through the study of proteins that interact with REPAT1 using the yeast two-hybrid technique. With that purpose, we constructed a cDNA library containing genes that are expressed in the midgut of fifth instar larvae of S. exigua. In the yeast-two hybrid experiments, two proteins showed interaction with the REPAT1 protein. These proteins were REPAT4 and a novel protein similar to this one, which was sequenced and named REPAT8. In cellular localization studies, REPAT1 was found in the cellular cytoplasm, but in the presence of REPAT8, REPAT1 also appears in the nucleus. The expression analysis of the eight repat genes described so far showed an overall response to the treatments related to B. thuringiensis (Cry1Ca toxin, XentariTM and a B. thuringiensis strain that does not produce Cry toxins, Bt cry-) but not with the treatments of non-pathogenic bacteria (Escherichia coli, Enterococcus spp. and other present in their microbiota), suggesting that the expression of these genes is activated mainly in response to cell damage. In a third chapter, taking advantage of the recent sequencing of the S. exigua transcriptome by our group, we tried to identify novel repat genes. The transcriptome analysis revealed the presence of at least 46 different members. Analysis of these sequences showed the presence of certain conserved motifs and their possible classification into two main classes: αREPATs and βREPATs. Also in this chapter we studied the expression of this gene superfamily, observing a change in the expression of αrepats in the midgut after exposure to Cry1Ca but not by an increased of microbiota in the larval gut. We studied the repat gene expression in midgut stem cells compared with the whole midgut tissue from S. exigua larvae. Interestingly, larvae with higher bacterial load in midgut showed a higher number of genes expressed in these stem cells. The increase of the number of sequences in S. exigua has allowed the identification of homologs in other insect species: Spodoptera frugiperda, Spodoptera littoralis, Spodoptera litura, Mamestra configurata, Mamestra brassicae, Helicoverpa armigera, Bombyx mori and the dipteran Drosophila melanogaster. In the model organism D. melanogaster, two homologs were identified: CG13323 and CG13324. Since in Drosophila there are molecular tools that are not available in S. exigua, we decided to study these homologous genes to increase our knowledge about repat genes. With that purpose, two types of mutants were obtained: a mutant with the deletion of CG13323 and CG13324, as well as CG13323 over-expressing mutants. The mutant with both deleted genes showed an increase in survival to Pseudomonas entomophila infection, which was contrary to the expected result because the genes showed increased expression after infection. There was also an increase in the survival of both larvae and adults in CG13323 over-expressing mutants. To test whether overexpression of CG13323 was involved in some of the routes of the immune system of D. melanogaster, we studied the expression of some marker genes (diptericin for the Imd pathway, upd3 for the JAK-STAT pathway and vein for the EGF pathway), finding no changes related to the over-expression of CG13323 and enabled us to locate the repat genes in some of the main routes of the insect immune system. Due to the characteristics of these genes and their encoded proteins: the large number of members of the same family, their different response at the expression level, the small size of the proteins, the interaction between members of the same family that produces nuclear translocation, and the homology of some members with transcriptional factors such as MBF2, suggest the possibility that different combinations of REPAT proteins could be responsible of transcriptional regulation of genes involved in various aspects of the insect physiology

Stand Delineation of Pinus sylvestris L. Plantations Suffering Decline Processes Based on Biophysical Tree Crown Variables: A Necessary Tool for Adaptive Silviculture

Many planted Pinus forests are severely affected by defoliation and mortality processes caused by pests and droughts. The mapping of forest tree crown variables (e.g., leaf area index and pigments) is particularly useful in stand delineation for the management of declining forests. This work explores the potential of integrating multispectral WorldView-2 (WV-2) and Airborne Laser Scanning (ALS) data for stand delineation based on selected tree crown variables in Pinus sylvestris plantations in southern Spain. Needle pigments (chlorophyll and carotenes) and leaf area index (LAI) were quantified. Eight vegetation indices and ALS-derived metrics were produced, and seven predictors were selected to estimate and map tree crown variables using a Random Forest method and Gini index. Chlorophylls a and b (Chla and Chlb) were significantly higher in the non-defoliated and moderately defoliated trees than in severely defoliated trees (F = 14.02, p < 0.001 for Chla; F = 13.09, p < 0.001 for Chlb). A similar response was observed for carotenoids (Car) (F = 14.13, p < 0.001). The LAI also showed significant differences among the defoliation levels (F = 26.5, p < 0.001). The model for the chlorophyll a pigment used two vegetation indices, Plant Senescence Reflectance Index (PSRI) and Carotenoid Reflectance Index (CRI); three WV-2 band metrics, and three ALS metrics. The model built to describe the tree Chlb content used similar variables. The defoliation classification model was established with a single vegetation index, Green Normalized Difference Vegetation Index (GNDVI); two metrics of the blue band, and two ALS metrics. The pigment contents models provided R2 values of 0.87 (Chla, RMSE = 12.98%), 0.74 (Chlb, RMSE = 10.39%), and 0.88 (Car, RMSE = 10.05%). The cross-validated confusion matrix achieved a high overall classification accuracy (84.05%) and Kappa index (0.76). Defoliation and Chla showed the validation values for segmentations and, therefore, in the generation of the stand delineation. A total of 104 stands were delineated, ranging from 6.96 to 54.62 ha (average stand area = 16.26 ha). The distribution map of the predicted severity values in the P. sylvestris plantations showed a mosaic of severity patterns at the stand and individual tree scales. Overall, the findings of this work underscore the potential of WV-2 and ALS data integration for the assessment of stand delineation based on tree health status. The derived cartography is a relevant tool for developing adaptive silvicultural practices to reduce Pinus sylvestris mortality in planted forests at risk due to climate change

Evaluación de la cobertura de la vegetación después de un incendio mediante análisis de mezclas espectrales. Aplicación y comparación de diferentes métodos de caracterización de factores de referencia

The analysis of satellite images allows one to monitor the regeneration of vegetation after a fire. In this work, a methodology for quantifying post fire vegetation cover was developed. The proposed methodology is based on the examination of Landsat 7 ETM+ images by using Spectral Mixture Analysis (SMA) and involves the following steps: a) pre-processing, b) inherent dimensionality image determination c) endmember characterization following two methods that thus lead to different models: traditional method based on the knowledge of the area worked as well as Minimum Noise Fraction and Pixel Purity Index method, d) model inversion and combination, e) comparison between the vegetation cover estimated by each model and that measured in field, and f) selection of the most accurate model and mapping of the vegetation cover for the study area. The cover estimated provided by the different models exhibited a high correlation (Spearman’s correlation coefficient &gt;0.89). The average absolute difference between the estimated and field-measured vegetation cover obtained with the most accurate model for each fire never exceeded 6%.El an&aacute;lisis de im&aacute;genes de sat&eacute;lite permite el seguimiento y evaluaci&oacute;n de los procesos de restauraci&oacute;n post-incendio. En este trabajo se presentan parte de los resultados de una metodolog&iacute;a dirigida a la cuantificaci&oacute;n de la cobertura de la vegetaci&oacute;n despu&eacute;s de un incendio. La metodolog&iacute;a propuesta se basa en el empleo de im&aacute;genes Landsat 7 ETM+ mediante un An&aacute;lisis de Mezclas Espectrales (SMA) y supone los siguientes procesos: a) pre-procesado de la imagen, b) determinaci&oacute;n de la dimensi&oacute;n intr&iacute;nseca (inherent dimensionality) de la imagen c) selecci&oacute;n y caracterizaci&oacute;n de los factores de referencia (endmember) mediante dos m&eacute;todos propuestos en la literatura: estudio previo de la zona de trabajo, Minimum Noise Fraction y pixles puros (Pixel Purity Index), d) inversi&oacute;n del modelo y combinaci&oacute;n, e) comparaci&oacute;n entre la cobertura estimada por cada modelos y las medidas realizadas en el campo, y f) selecci&oacute;n del modelo de mayor precisi&oacute;n para la realizaci&oacute;n de una cartograf&iacute;a de la cobertura de la vegetaci&oacute;n en el &aacute;rea de estudio. La cobertura estimada por los diferentes modelos muestran una alta correlaci&oacute;n (Coeficiente de correlaci&oacute;n de Spearman &gt; 0.89), lo que ha permitido establecer una diferencia entre las medidas de cobertura a trav&eacute;s de la imagen y la estimaci&oacute;n de campo que en ning&uacute;n caso han superado el 6% de la cobertura post-inendio

Caracterización del material forestal de reproducción de cinco procedencias de Nothofagus alessandrii Espinosa, una especie en peligro de extinción

Nothofagus alessandrii es una especie endémica de la zona mesomórfica de Chile que se encuentra en peligro de extinción y de la cual existe aún información insuficiente respecto de las diferencias entre sus poblaciones. Por ello, en este trabajo se analizan y caracterizan parámetros cualitativos y cuantitativos del material germinativo y el comportamiento en vivero de cinco procedencias representativas del área de distribución natural de la especie. Se colectaron semillas de estas procedencias en febrero 2000 y se determinó su tamaño, forma, peso y capacidad germinativa. En septiembre del mismo año se cultivaron plantas en vivero y se evaluó su crecimiento diametral y en altura. Los resultados indican que el tamaño de las semillas es, en general, homogéneo y solo se observan diferencias estadísticas en la longitud de las dímeras y ancho de las trímeras. El peso de 1000 semillas y la capacidad germinativa varió significativamente entre las procedencias. El desarrollo de las plantas en vivero fue homogéneo y no hubo diferencias en el diámetro de cuello de la raíz ni en la altura que alcanzaron las plantas después de una temporada de cultivo. N. alessandrii tiene un comportamiento diferente al de otras especies del mismo género, sin que se observe una variación de tipo clinal. Sin embargo, la procedencia más austral tiende a diferenciarse de las otras y, probablemente, corresponda a un ecotipo diferente.Nothofagus alessandrii is an endemic and endangered species from the mesomorphic zone of Chile. Currently, differences across populations are not well known. To this end, quantitative and qualitative parameters pertaining to germinative material and nursery performance of seedlings from five provenances representing the natural distribution of the species were analyzed and characterized. Seeds were collected in February 2000 and size, form, weight, and germination capacity were determined. Seedlings were then cultivated in nursery in September of the same year, and basal diameter and height growth were quantified. Results indicate that seed size is generally homogeneous across sites, and statistical differences were limited to length of dimerous seeds and width of trimerous seeds. Seed weight and germination capacity varied significantly among the provenances. After one cultivation season, the development of the nursery plants was homogenous across provenances, with no differences in basal diameter or height. N. alessandrii differs, in relation to the variation among the studied provenances, from that of other species of the same genus, with the exception of a pronounced clinal type. However, the southernmost provenance tended, in general, to differ from the other ones and likely represents a different ecotype.Nothofagus alessandrii é uma espécie endêmica da zona mesomórfica do Chile que se encontra em perigo de extinção e da qual existe ainda informação insuficiente em relação às diferenças entre suas populações. Por isto, neste trabalho se analisam e caracterizam parâmetros qualitativos e quantitativos do material germinativo e o comportamento em viveiro de cinco procedências representativas da área de distribuição natural da espécie. Recolheram-se sementes destas procedências em fevereiro de 2000 e se determinou seu tamanho, forma, peso e capacidade germinativa. Em setembro do mesmo ano se cultivaram plantas em viveiro e se avaliou seu crescimento diametral e em altura. Os resultados indicam que o tamanho das sementes é, em geral, homogêneo e somente se observam diferenças estatísticas no comprimento das dímeras e largura das trímeras. O peso de 1.000 sementes e a capacidade germinativa variou significativamente em relação às procedências. O desenvolvimento das plantas em viveiro foi homogêneo e não houve diferenças no diâmetro do colo da raíz nem na altura que alcançaram as plantas depois de uma temporada de cultivo. N. alessandrii tem um comportamento diferente ao de outras espécies do mesmo gênero, sem que se observe uma variação do tipo clinal. No entanto, a procedência mais austral tende a diferenciar-se das outras e, provavelmente, corresponda a um ecótipo diferent