Microwave extraction and molecular imprinted polymer isolation of bergenin applied to the dendrochronological chemical study of Peltophorum dubium.

This study describes methodologies for extracting and isolating bergenin, a C-glucoside of 4-O-methylgallic acid found in some plants and it presents various in vitro and in vivo biological activities. Bergenin was previously obtained from the Pelthophorum dubim (Fabaceae) roots with a good yield. Conventional chromatographic procedures of the CHCl3 soluble fraction of the MeOH extract gave 3.62% of this glucoside. An HPLC/DAD method was also developed and validated for bergenin and its precursor, gallic acid quantifications. Microwave extractions with different solvents were tested to optimize the extraction of bergenin, varying the temperature and time. MAE (Microwave Assisted Extraction) was more efficient than conventional extraction procedures, giving a higher yield of bergenin per root mass (0.45% vs. 0.0839%). Molecularly imprinted polymer (MIP) and non-imprinted polymer (NIP) based on bergenin as the template molecule, methacrylic acid, and ethylene glycol dimethacrylate were synthesized and characterized by FTIR and SEM (Scanning Electron Microscopy). Bergenin adsorption experiments using MIP and NIP followed by molecular imprinted solid phase extraction (MISPE) showed that MIP had a higher selectivity for bergenin than NIP. A dendrochronological study using the proposed method for detection and quantification of gallic acid and bergenin in five P. dubium growth rings of a 31-year-old heartwood and in the phelloderm and barks indicated that bergenin was more abundant in the 11-14th growth rings of the heartwood and decreased from the heartwood to the barks.

Potencial dendrocronológico de tres especies de Podocarpáceas de la Cordillera de los Andes / Dendrochronological potential of three Podocarpaceae species from the Andean Cordillera

Resumen Introducción: Poco se conoce del potencial dendrocronológico de las Podocarpáceas en el trópico. Objetivo: Explorar el potencial dendrocronológico de tres especies de podocarpáceas: Retrophyllum rospigliosii, Podocarpus oleifolius y Prumnopitys harmsiana. Métodos: De plantaciones no manejadas localizadas en los Andes colombianos, se muestrearon y analizaron 88 árboles: 30 muestras de R. rospigliosii provenientes de secciones transversales, 30 y 28 muestras de P. oleifolius y P. harmsiana, respectivamente, provenientes de núcleos de madera extraídos con barreno de incrementos. Las muestras se procesaron siguiendo las técnicas dendrocronológicas estándar. Resultados: En general, las características anatómicas de los anillos de crecimiento son similares para las tres especies, con una anatomía simple de traqueidas alineadas radialmente por tratarse de coníferas. Dado que la edad conocida de la plantación coincide con el número de anillos se considera una fuerte evidencia de la frecuencia anual de su formación en R. rospigliosii y P. oleifolius, las cuales presentaron buena sincronización (cofechado) con una inter-correlación promedio de 0.55 (r-Pearson). Para P. harmsiana no fue posible concretar series de ancho de anillos de las muestras recolectadas. Las series estandarizadas de R. rospigliosii y P. oleifolius mostraron una relación con los registros instrumentales de precipitación y temperatura, indicando que estas especies pueden ser promisorias para estudios adicionales. Conclusión: La investigación dendrocronología con especies de Podocarpáceas podría realizarse exitosamente con R. rospigliosii y P. oleifolius, pero no con P. harmsiana.

Abstract Introduction: Little is known about the dendrochronological potential of Podocarpaceaes in the tropics. Objective: To explore the dendrochronological potential of three Podocarpaceae species: Retrophyllum rospigliosii, Podocarpus oleifolius, and Prumnopitys harmsiana. Methods: From a non-managed plantation in the Andean cordillera in Colombia, a total of 88 trees were analyzed: 30 samples of cross-sections of R. rospigliosii, and 30 and 28 samples of P. oleifolius and P. harmsiana, respectively, obtained with an increment borer. Samples were processed according to standard dendrochronological methods. Results: The anatomical characteristics of the growth rings of the three species are similar, with a simple conifer anatomy with radially oriented tracheids. Since the known age of the plantation coincides with the number of tree rings this is strong evidence of annual tree-ring frequency of R. rospigliosii and P. oleifolius which also showed a satisfactory cross-dating with an average inter-correlation of 0.55 (r-Pearson). For P. harmsiana, it was not possible to build a tree-ring series from the collected samples. R. rospigliosii and P. oleifolius standardized ring-width chronologies showed a relationship with the instrumental records of rainfall and temperature, indicating these species may be promising further studies. Conclusions: Dendrochronological research with Podocarpaceae species could be carried out successfully with R. rospigliosii and P. oleifolius but not with P. harmsiana.

Radiocarbon and wood anatomy as complementary tools for generating tree-ring records in Bolivia.

The science of tropical dendrochronology is now emerging in regions where tree-ring dating had previously not been considered possible. Here, we combine wood anatomical microsectioning techniques and radiocarbon analysis to produce the first tree-ring chronology with verified annual periodicity for a new dendrochronological species, Neltuma alba (commonly known as "algarrobo blanco") in the tropical Andes of Bolivia. First, we generated a preliminary chronology composed of six trees using traditional dendrochronological methods (i.e., cross-dating). We then measured the 14C content on nine selected tree rings from two samples and compared them with the Southern Hemisphere (SH) atmospheric 14C curves, covering the period of the bomb 14C peak. We find consistent offsets of 5 and 12 years, respectively, in the calendar dates initially assigned, indicating that several tree rings were missing in the sequence. In order to identify the tree-ring boundaries of the unidentified rings we investigated further by analyzing stem wood microsections to examine anatomical characteristics. These anatomical microsections revealed the presence of very narrow terminal parenchyma defining several tree-ring boundaries within the sapwood, which was not visible in sanded samples under a stereomicroscope. Such newly identified tree rings were consistent with the offsets shown by the radiocarbon analysis and allowed us to correct the calendar dates of the initial chronology. Additional radiocarbon measurements over a new batch of rings of the corrected dated samples resulted in a perfect match between the dendrochronological calendar years and the 14C dating, which is based on good agreement between the tree-ring 14C content and the SH 14C curves. Correlations with prior season precipitation and temperature reveal a strong legacy effect of climate conditions prior to the current Neltuma alba growing season. Overall, our study highlights much potential to complement traditional dendrochronology in tree species with challenging tree-ring boundaries with wood anatomical methods and 14C analyses. Taken together, these approaches confirm that Neltuma alba can be accurately dated and thereby used in climatic and ecological studies in tropical and subtropical South America.

Potencial dendroclimático del encino rojo, Quercus sideroxyla (Fagaceae) en México / Dendroclimatic potential of red oak, Quercus sideroxyla (Fagaceae) in Mexico

Resumen Introducción: Los estudios dendrocronológicos en México se han basado principalmente en las coníferas, mientras que las especies de madera dura han sido poco estudiadas. Este ha sido el caso del género Quercus, con una alta diversidad taxonómica en el país pero que no ha sido estudiado con fines dendrocronológicos, a pesar de los valores ecológicos y económicos de sus especies. Objetivo: En la presente investigación se determinó el potencial dendroclimático de Quercus sideroxyla en el noroeste de México, y su relación con variables climáticas como precipitación y temperatura. Métodos: La investigación se desarrolló en el estado de Durango en el ejido Chavarría Viejo en las coordenadas (23º43' N & 105º33' W), se recolectaron muestras de 5 a 7 cm en dos sitios bajo aprovechamiento forestal y se procesaron mediante técnicas dendrocronológicas convencionales. Resultados: Se desarrolló una cronología de ancho de anillo total, la cual se compuso por 30 muestras de 16 árboles para el período de 1917 a 2018 (101 años). Se obtuvieron valores de intercorrelación entre series de 0.43, de sensibilidad media de 0.36, relación señal-ruido de 3.53 y autocorrelación de primer orden (0.58). En cuanto a la relación clima-crecimiento, los valores de índice de ancho de anillo se correlacionaron con datos de la estación climática más cercana al sitio de estudio; donde la precipitación invierno-primavera (enero-mayo) fue la variable de mayor influencia en el crecimiento de la especie. Conclusiones: Con base en los parámetros dendrocronológicos se demuestra el alto potencial de la especie para ser empleada en estudios dendroclimáticos en la región, la respuesta de la especie a la precipitación es similar al de las coníferas con las que cohabita.

Abstract Introduction: Dendrochronological studies in Mexico have been mainly based on conifers, while hardwood species have been little studied. This has been the case of the genus Quercus, which has a high taxonomic diversity in the country but has not been previously studied for dendrochronological issues, despite the ecological and economic values of oak species. Objective: In the present investigation, the dendroclimatic potential of Quercus sideroxyla in Northwestern Mexico was determined, as well as its relationship with climatic variables such as precipitation and temperature. Methods: The research was carried out in the state of Durango, Chavarría Viejo with coordinates (23º43' N & -105º33' W). Samples of 5 cm to 7cm were collected in two sites under forest exploitation and processed by conventional dendrochronological techniques. Results: A chronology of total ring width was developed, which was composed of 30 samples from 16 trees for the period from 1917 to 2018 (101 years). Inter-series intercorrelation values of 0.43, mean sensitivity of 0.36, signal-to-noise ratio of 3.53 and first-order autocorrelation (0.58) were obtained. Regarding the climate-growth relationship, the ring width index values were correlated with data from the climatic station nearest to the study site, where winter-spring precipitation (January-May) was the variable with the greatest influence on the growth of the species. Conclusions: Based on the dendrochronological parameters, the high potential of the species that were used in dendroclimatic studies in the region has demonstrated that the response of the species to precipitation is similar to that of the conifers with which the Quercus sideroxyla shares its habitat with.

Reconstrucción histórica de la precipitación en la Reserva de la Biosfera El Cielo, México, mediante anillos de crecimiento en Taxodium mucronatum (Cupressaceae) / Historical precipitation reconstruction of El Cielo Biosphere Reserve, Mexico, using Taxodium mucronatum (Cupressaceae) annual growth rings

Introducción: El conocimiento histórico del clima es fundamental para analizar su variabilidad en el tiempo y su impacto en los ecosistemas y poblaciones humanas. Objetivo: Analizar el crecimiento anual de los árboles de sabino, también conocido como ahuehuete (Taxodium mucronatum) del río Sabinas para reconstruir la variabilidad de precipitación histórica en la Reserva de la Biosfera El Cielo, Tamaulipas, México. Métodos: Se fecharon los crecimientos anuales de 116 muestras de sabino, a partir de las cuales se desarrolló una cronología de 544 años (1474-2017). El periodo que sustentó un número de muestras adecuado para el análisis climático se extiende de 1550 a 2017 (468 años). Resultados: Con base en el análisis de función respuesta se determinó que la precipitación de invierno-primavera (noviembre-mayo) influyó de manera significativa en el crecimiento de los sabinos en el área de estudio (r= 0.77, P < 0.001). La reconstrucción registró una variabilidad climática alta a nivel interanual y entre décadas, en la cual, se identificó la presencia de sequías a principios y finales de cada siglo, así como la presencia de sequías extremas cíclicas cada 50 años. Estas sequías destacaron por su impacto social y económico a nivel nacional y regional. Las sequías más importantes son el "Año Uno Conejo" de acuerdo con el calendario Azteca, en 1558; la sequía de1696 con un impacto fuerte en el noreste de México; "El Año del Hambre" en 1785-1786, en la Reserva de la Biosfera El Cielo desde 1784; la sequía de 1801 que trajo consigo la escasez de alimentos; la de 1951 dentro del periodo de "Migración masiva del sector rural"; y la sequía más reciente, registrada en 2011. Las lluvias extremas más representativas sucedieron en 1756 y 1816. Conclusiones: De seguir el patrón de precipitación registrado en la Reserva de la Biosfera El Cielo, es posible esperar la presencia de sequías extremas a mediados y finales del siglo XXI.

Introduction: Historical knowledge of climate is essential to analyze its variability over time, as well as its impact on natural ecosystems and human populations. Objective: To analyze the annual growth of the sabino trees, also known as ahuehuete trees (Taxodium mucronatum) from the Sabinas River to reconstruct the historical variability of precipitation in El Cielo Biosphere Reserve, Tamaulipas, Mexico. Methods: The annual growth of 116 sabino samples was dated to develop a chronology of 544 years (1474-2017). The period that admitted a series of samples suitable for climate analysis extends from 1550 to 2017 (468 years). Results: Based on the analysis of the response function, it was determined that the winter-spring precipitation (November-May) significantly influenced the radial growth of sabinos in the study area (R= 0.77, P < 0.001). The reconstruction recorded high climatic variability at interannual and interdecadal levels, in which the presence of droughts was identified at the beginning and end of each century, as well as the presence of extreme cyclical droughts every 50 years. These droughts stood out for their social and economic impact at the regional and national level. The most important droughts are the "Año Uno Conejo" ("Year One Rabbit") according to the Aztec calendar in 1558. In 1696 with a strong impact in Northern Mexico. "El Año del Hambre" ("The Year of Hunger") in 1785-1786. Also, the drought of 1801 that brought alongside food shortages. 1951 within the period of "Mass migration of the rural sector"; and the most recent drought, recorded in 2011. The most representative extreme rainfalls occurred in 1756 and 1816. Conclusions: If the precipitation pattern registered at El Cielo Biosphere Reserve continues, it is possible to expect the presence of extreme droughts in the mid and late 21st century.

Intra-annual oxygen isotopes in the tree rings record precipitation extremes and water reservoir levels in the Metropolitan Area of São Paulo, Brazil.

The impacts of climate change on precipitation and the growing demand for water have increased the water risks worldwide. Water scarcity is one of the main challenges of the 21st century, and the assessment of water risks is only possible from spatially distributed records of historical climate and levels of water reservoirs. One potential method to assess water supply is the reconstruction of oxygen isotopes in rainfall. We here investigated the use of tree-ring stable isotopes in urban trees to assess spatial/temporal variation in precipitation and level of water reservoirs. We analyzed the intra-annual variation of δ13C and δ18O in the tree rings of Tipuana tipu trees from northern and southern Metropolitan Area of São Paulo (MASP), Brazil. While variation in δ13C indicates low leaf-level enrichments from evapotranspiration, δ18O variation clearly reflects precipitation extremes. Tree-ring δ18O was highest during the 2014 drought, associated with the lowest historical reservoir levels in the city. The δ18O values from the middle of the tree rings have a strong association with the mid-summer precipitation (r = -0.71), similar to the association between the volume of precipitation and its δ18O signature (r = -0.76). These consistent results allowed us to test the association between tree-ring δ18O and water-level of the main reservoirs that supply the MASP. We observed a strong association between intra-annual tree-ring δ18O and the water-level of reservoirs in the northern and southern MASP (r = -0.94, r = -0.90, respectively). These results point to the potential use of high-resolution tree-ring stable isotopes to put precipitation extremes, and water supply, in a historical perspective assisting public policies related to water risks and climate change. The ability to record precipitation extremes, and previously reported capacity to record air pollution, place Tipuana tipu in a prominent position as a reliable environmental monitor for urban locations.

Impact of temperature on the growth of a Neotropical tree species (Hymenaea courbaril, Fabaceae) at its southern distribution limit.

Widely distributed tree species usually face different growth conditions across gradients of climate variables. Hymenaea courbaril inhabits most of Neotropical lowlands, where its growth is limited by low precipitation under seasonal precipitation regimes. However, it is still unclear what are the drivers of growth variability at its distribution limits, where populations are most vulnerable to climate change. We evaluated the role of precipitation and temperature variability on the growth rate of two populations of H. courbaril at the southern limits of its occurrence. Sampling sites comprise two semi-deciduous forest fragments with weathered and chemically poor soils, similar temperature conditions, only differing in size and in precipitation regime. To achieve that goal, we built two tree-ring chronologies using standard dendrochronological methods, one with 21 trees (37 radii) and the other one with 13 trees (24 radii). First, we evaluated if site conditions would affect average growth patterns, and then, we tested the climate-growth relationships and the teleconnections with the Equatorial Pacific sea surface temperature (SST). The results show that trees display similar average growth rates throughout life without evidence of influence from differing fragment sizes. Nonetheless, precipitation positively influences annual growth in the drier site, while it has a negative effect on growth in the wetter site. In contrast to previous studies, temperature has a stronger influence than precipitation on the growth of these trees. Monthly, seasonal, and annual mean temperatures showed a negative influence on trees growth. The variability of the regional temperature and, consequently, of the growth rate of the trees is partially dependent on the SST of the Equatorial Pacific. In conclusion, this study shows that temperature is a key limiting growth factor for this species at its southern distribution limits and periods with warmer temperature will likely reduce annual growth rate.

The role of air pollution and climate on the growth of urban trees.

The urban environment features poor air quality and harsher climate conditions that affect the life in the cities. Citizens are especially vulnerable to climate change, because heat island and impervious exacerbates extreme climate events. Urban trees are important tools for mitigation and adaptation of cities to climate change because they provide ecosystem services that increase while trees grow. Nonetheless, the growth of trees may be affected by the harsher conditions found in the urban environment. We assessed the impact of air pollution and climate on the spatial/temporal variability of tree growth in São Paulo, Brazil, one of the largest urban conglomerates in the world. For this purpose, we sampled 41 trees of the Tipuana tipu species in a region that includes industrial areas. We built a tree-ring chronology using standard dendrochronological methods. Spatial analyses show that trees grow faster in the warmer parts of the city and under higher concentrations of airborne P, whereas growth is reduced under higher concentrations of Al, Ba, Zn. Particulate matter (PM10) from the industrial cluster also reduce average growth rate of trees, up to 37% in all diameter classes. Similar results were obtained via temporal analyses, suggesting that the annual growth rate is positively associated with temperature, which explain 16% of interannual growth variability. Precipitation, on the other hand, has no association with tree growth. The average concentration of PM10 explains 41% of interannual growth variability, and higher concentrations during the driest months reduce growth rate. Despite heat island effect and water limitation in the soil of the city, this species takes advantage of warmer conditions and it is not limited by water availability as measured by precipitation. On the other hand, air pollution directly impacts the growth of these trees being a major limiting growth factor.

Potencial de Copaifera langsdorffii Desf. (Fabaceae) como indicadora de mudanças climáticas por meio da análise dos anéis de crescimento, Paraná, Brasil / Copaifera langsdorffii Desf. (Fabaceae) potential as an indicator of climate change by tree ring analysis, Parana, Brazil

No âmbito do atual tema das mudanças climáticas, ter acesso a ferramentas que permitam a sua análise torna-se essencial para a correta compreensão de tais alterações. A interpretação dos sinais climáticos evidenciados nos anéis de crescimento das árvores é uma das maneiras de entender essas relações. Portanto, este trabalho teve como objetivo avaliar como as relações climáticas regionais tem efeito sobre os anéis de crescimento de Copaifera langsdorffii, espécie típica das florestas estacionais semideciduais do Paraná. Foram utilizadas quatro árvores provenientes da supressão da vegetação para formação do reservatório da Usina Hidrelétrica Jayme Canet Júnior, na porção média do rio Tibagi, entre os municípios de Telêmaco Borba e Ortigueira. A partir dos discos transversais de madeira, foram traçados 40 raios com o intuito de identificar e demarcar os limites dos anéis de crescimento. Posteriormente, a largura dos anéis de crescimento foi mensurada, realizando-se o controle de qualidade destas medições e a construção de uma cronologia regional para a espécie. Os dados climáticos utilizados para as correlações foram obtidos junto aos institutos oficiais de meteorologia do Paraná e junto à um banco de dados climatológico global. A cronologia gerada compreende um período de 240 anos, com intercorrelação significativa (r = 0,469; p<0,01). Foram identificadas as relações dos picos de desenvolvimento com os eventos de El Niño, onde apresentaram correlações positivas a partir da década de 1970, especialmente no ano de 1983 (El Niño mais forte atuante na região Sul). Dessa maneira, os resultados preliminares reforçam o potencial de utilização desta espécie para estudos dendroecológicos podendo, inclusive, auxiliar no entendimento das mudanças climáticas, e como se dão os seus efeitos a nível regional e local, quando incorporados a um universo amostral com maior representatividade.

Under the current issue of climate change, having access to tools that allow its analysis has become essential for the correct understanding of such changes. The interpretation of climatic signals evidenced in tree rings is one of the ways to understand these relations. Therefore, this study aimed to evaluate how regional climatic relationships have an effect on the Copaifera langsdorffii growth rings, a typical species of the seasonal semideciduous forests of Parana. We used four trees as a result of the vegetation suppression to form the reservoir of the Jayme Canet Júnior Hydroelectric Power Plant, in the middle portion of the Tibagi River, between the municipalities of Telemaco Borba and Ortigueira. From the cross sections of the trees, 40 series were drawn in order to identify and demarcate the limits of the growth rings. Then, we measured the width of the growth rings and performed a quality control and the construction of a regional chronology for the species. The climatic data used for these correlations were obtained from the official meteorological institutes of Parana and a global climate database. The chronology has 240 years, with significant intercorrelation (r = 0,469, p <0.01). The relationship between development peaks and El Niño events was identified, with positive correlations from the 1970s, especially in 1983 (strongest El Niño in Southern Brazil). In this way, the preliminary results reinforce this species potential to be used for dendroecological studies, which may also help in the understanding of climatic changes, as well as their effects at a regional and local level, when incorporated into a sample universe of greater representativity.

Potencial de Copaifera langsdorffii Desf. (Fabaceae) como indicadora de mudanças climáticas por meio da análise dos anéis de crescimento, Paraná, Brasil / Copaifera langsdorffii Desf. (Fabaceae) potential as an indicator of climate change by tree ring analysis, Parana, Brazil

No âmbito do atual tema das mudanças climáticas, ter acesso a ferramentas que permitam a sua análise torna-se essencial para a correta compreensão de tais alterações. A interpretação dos sinais climáticos evidenciados nos anéis de crescimento das árvores é uma das maneiras de entender essas relações. Portanto, este trabalho teve como objetivo avaliar como as relações climáticas regionais tem efeito sobre os anéis de crescimento de Copaifera langsdorffii, espécie típica das florestas estacionais semideciduais do Paraná. Foram utilizadas quatro árvores provenientes da supressão da vegetação para formação do reservatório da Usina Hidrelétrica Jayme Canet Júnior, na porção média do rio Tibagi, entre os municípios de Telêmaco Borba e Ortigueira. A partir dos discos transversais de madeira, foram traçados 40 raios com o intuito de identificar e demarcar os limites dos anéis de crescimento. Posteriormente, a largura dos anéis de crescimento foi mensurada, realizando-se o controle de qualidade destas medições e a construção de uma cronologia regional para a espécie. Os dados climáticos utilizados para as correlações foram obtidos junto aos institutos oficiais de meteorologia do Paraná e junto à um banco de dados climatológico global. A cronologia gerada compreende um período de 240 anos, com intercorrelação significativa (r = 0,469; p<0,01). Foram identificadas as relações dos picos de desenvolvimento com os eventos de El Niño, onde apresentaram correlações positivas a partir da década de 1970, especialmente no ano de 1983 (El Niño mais forte atuante na região Sul). Dessa maneira, os resultados preliminares reforçam o potencial de utilização desta espécie para estudos dendroecológicos podendo, inclusive, auxiliar no entendimento das mudanças climáticas, e como se dão os seus efeitos a nível regional e local, quando incorporados a um universo amostral com maior representatividade.(AU)

Under the current issue of climate change, having access to tools that allow its analysis has become essential for the correct understanding of such changes. The interpretation of climatic signals evidenced in tree rings is one of the ways to understand these relations. Therefore, this study aimed to evaluate how regional climatic relationships have an effect on the Copaifera langsdorffii growth rings, a typical species of the seasonal semideciduous forests of Parana. We used four trees as a result of the vegetation suppression to form the reservoir of the Jayme Canet Júnior Hydroelectric Power Plant, in the middle portion of the Tibagi River, between the municipalities of Telemaco Borba and Ortigueira. From the cross sections of the trees, 40 series were drawn in order to identify and demarcate the limits of the growth rings. Then, we measured the width of the growth rings and performed a quality control and the construction of a regional chronology for the species. The climatic data used for these correlations were obtained from the official meteorological institutes of Parana and a global climate database. The chronology has 240 years, with significant intercorrelation (r = 0,469, p <0.01). The relationship between development peaks and El Niño events was identified, with positive correlations from the 1970s, especially in 1983 (strongest El Niño in Southern Brazil). In this way, the preliminary results reinforce this species potential to be used for dendroecological studies, which may also help in the understanding of climatic changes, as well as their effects at a regional and local level, when incorporated into a sample universe of greater representativity.(AU)

How are monospecific stands of invasive trees formed? Spatio-temporal evidence from Douglas fir invasions.

Invasive plant species can produce many impacts on native communities. Impacts can be especially important when the non-natives reach high densities, producing monospecific stands where little grows besides the non-native species. We propose three basic pathways by which monospecific stands of invasive tree species are formed: (i) gradually from the propagule source, (ii) via synchronous establishment and (iii) following several pulses of synchronous establishment. Different patterns can produce different impacts through time and may require different management techniques. This study aims to further our understanding of how monotypic stands of invasive species arise. We documented how monospecific stands are formed during invasion processes by studying patterns of spatio-temporal establishment of several monospecific stands of Douglas fir in Patagonia. We obtained data on tree density, year of establishment, size, distance to the seed source and other related measurements for this tree species along transects from the original seed source (80-year-old plantations) to the edge of the monospecific stand. We found that these monospecific stands arose in a more complex way than expected. While individuals established on average simultaneously over all distances from the seed source, there was substantial variation in time of establishment at all distances. Also, tree density was higher near the source than far from it. Different factors can account for the observed pattern of tree establishment, including seed dispersal, mycorrhizal facilitation and herbivory. Our results elucidate the complexities of spatio-temporal pattern of formation in monospecific stands. This understanding can improve management strategies and techniques for this invasion and other plant invasions in different regions.

Nonannual tree rings in a climate-sensitive Prioria copaifera chronology in the Atrato River, Colombia.

In temperate climates, tree growth dormancy usually ensures the annual nature of tree rings, but in tropical environments, determination of annual periodicity can be more complex. The purposes of the work are as follows: (1) to generate a reliable tree-ring width chronology for Prioria copaifera Griseb. (Leguminoceae), a tropical tree species dwelling in the Atrato River floodplains, Colombia; (2) to assess the climate signal recorded by the tree-ring records; and (3) to validate the annual periodicity of the tree rings using independent methods. We used standard dendrochronological procedures to generate the P. copaifera tree-ring chronology. We used Pearson correlations to evaluate the relationship of the chronology with the meteorological records, climate regional indices, and gridded precipitation/sea surface temperature products. We also evaluated 24 high-precision 14C measurements spread over a range of preselected tree rings, with assigned calendar years by dendrochronological techniques, before and after the bomb spike in order to validate the annual nature of the tree rings. The tree-ring width chronology was statistically reliable, and it correlated significantly with local records of annual and October-December (OND) streamflow and precipitation across the upper river watershed (positive), and OND temperature (negative). It was also significantly related to the Oceanic Niño Index, Pacific Decadal Oscillation, and the Southern Oscillation Index, as well as sea surface temperatures over the Caribbean and the Pacific region. However, 14C high-precision measurements over the tree rings demonstrated offsets of up to 40 years that indicate that P. copaifera can produce more than one ring in certain years. Results derived from the strongest climate-growth relationship during the most recent years of the record suggest that the climatic signal reported may be due to the presence of annual rings in some of those trees in recent years. Our study alerts about the risk of applying dendrochronology in species with challenging anatomical features defining tree rings, commonly found in the tropics, without an independent validation of annual periodicity of tree rings. High-precision 14C measurements in multiple trees are a useful method to validate the identification of annual tree rings.

Growth and reproduction respond differently to climate in three Neotropical tree species.

The response of tropical forests to anthropogenic climate change is critically important to future global carbon budgets, yet remains highly uncertain. Here, we investigate how precipitation, temperature, solar radiation and dry- and wet-season lengths are related to annual tree growth, flower production, and fruit production in three moist tropical forest tree species using long-term datasets from tree rings and litter traps in central Panama. We also evaluated how growth, flower, and fruit production were interrelated. We found that growth was positively correlated with wet-season precipitation in all three species: Jacaranda copaia (r = 0.63), Tetragastris panamensis (r = 0.39) and Trichilia tuberculata (r = 0.39). Flowering and fruiting in Jacaranda were negatively related to current-year dry-season rainfall and positively related to prior-year dry-season rainfall. Flowering in Tetragastris was negatively related to current-year annual mean temperature while Trichilia showed no significant relationships of reproduction with climate. Growth was significantly related to reproduction only in Tetragastris, where it was positively related to previous year fruiting. Our results suggest that tree growth in moist tropical forest tree species is generally reduced by drought events such as those associated with strong El Niño events. In contrast, interannual variation in reproduction is not generally associated with growth and has distinct and species-specific climate responses, with positive effects of El Niño events in some species. Understanding these contrasting climate effects on tree growth and reproduction is critical to predicting changes in tropical forest dynamics and species composition under climate change.

Growth ring analysis of Euxylophora paraensis through x-ray microdensitometry / Análise dos anéis de crescimento de Euxylophora paraensis por meio da microdensitometria de raios-x

Euxylophora paraensis Huber - Rutaceae, popularly known as yellow heart, is a species with a low-density population that has suffered intense exploitation in recent decades. This has led to its inclusion in the IBAMA list of endangered species. This study aimed to evaluate the existence of growth rings and their annuity in five trees of Euxylophora paraensis through the x-ray microdensitometry technique, as well as to compare them using the classical method. Application feasibility of this technique can be deepened through future, broader dendroecological studies, which may better elucidate the understanding of the species population dynamics and promote more sustainable uses. Wood disks were collected from the base of five 29-year-old trees from a planting site in the Curua-Una Experimental Station, located in Prainha, Pará State, Brazil. Samples were polished and sanded for the x-ray microdensitometric analysis. Values of minimum, average, and maximum density (0.581, 0.84, and 1.077gcm-3, respectively) were obtained. There was a significant difference in density between the studied trees. Growth rings boundaries, through densitometric pith-bark profile are demarcated by fibrous zones, with density variation between the early wood and late wood. This study concludes that the growth rings of the studied species are distinct and annual, validating the technique used.

Euxylophora paraensis Huber - Rutaceae, popularmente conhecida como pau amarelo, é uma espécie com baixa densidade populacional e que sofreu intensa exploração nas últimas décadas. Isso levou à sua inclusão na lista do IBAMA de espécies ameaçadas de extinção. O presente estudo objetiva avaliar a existência e anuidade dos anéis de crescimento de cinco árvores de Euxylophora paraensis, por meio da técnica de microdensitometria de Raio-x, e comparar com o uso do método clássico. A viabilidade da aplicação dessa técnica poderá ser aprofundada por meio de futuros estudos dendroecológicos mais amplos, que poderão melhor elucidar a compreensão da dinâmica populacional da espécie e promover usos mais sustentáveis. Coletou-se discos do lenho da base de cinco árvores, provenientes de plantio, na Estação experimental de Curua-Una, em Prainha PA, com então 29 anos de idade. As amostras foram plainadas e polidas, visando a análise microdensitometrica de raios x. Foram obtidos valores de densidade mínimos, médios e máximos (respectivamente 0,581, 0,84 e 1,077gcm-3). Houve diferença significativa na densidade entre as árvores estudadas. Verificou-se, por meio do perfil densitométrico no sentido medula casca, limites dos anéis de crescimento por zonas fibrosas, com variação da densidade entre o lenho inicial e tardio. Verifica-se que os anéisde crescimento da espécie estudada são distintos e anuais, validando a técnica utilizada.

Growth ring analysis of Euxylophora paraensis through x-ray microdensitometry / Análise dos anéis de crescimento de Euxylophora paraensis por meio da microdensitometria de raios-x

Euxylophora paraensis Huber - Rutaceae, popularly known as yellow heart, is a species with a low-density population that has suffered intense exploitation in recent decades. This has led to its inclusion in the IBAMA list of endangered species. This study aimed to evaluate the existence of growth rings and their annuity in five trees of Euxylophora paraensis through the x-ray microdensitometry technique, as well as to compare them using the classical method. Application feasibility of this technique can be deepened through future, broader dendroecological studies, which may better elucidate the understanding of the species population dynamics and promote more sustainable uses. Wood disks were collected from the base of five 29-year-old trees from a planting site in the Curua-Una Experimental Station, located in Prainha, Pará State, Brazil. Samples were polished and sanded for the x-ray microdensitometric analysis. Values of minimum, average, and maximum density (0.581, 0.84, and 1.077gcm-3, respectively) were obtained. There was a significant difference in density between the studied trees. Growth rings boundaries, through densitometric pith-bark profile are demarcated by fibrous zones, with density variation between the early wood and late wood. This study concludes that the growth rings of the studied species are distinct and annual, validating the technique used.(AU)

Euxylophora paraensis Huber - Rutaceae, popularmente conhecida como pau amarelo, é uma espécie com baixa densidade populacional e que sofreu intensa exploração nas últimas décadas. Isso levou à sua inclusão na lista do IBAMA de espécies ameaçadas de extinção. O presente estudo objetiva avaliar a existência e anuidade dos anéis de crescimento de cinco árvores de Euxylophora paraensis, por meio da técnica de microdensitometria de Raio-x, e comparar com o uso do método clássico. A viabilidade da aplicação dessa técnica poderá ser aprofundada por meio de futuros estudos dendroecológicos mais amplos, que poderão melhor elucidar a compreensão da dinâmica populacional da espécie e promover usos mais sustentáveis. Coletou-se discos do lenho da base de cinco árvores, provenientes de plantio, na Estação experimental de Curua-Una, em Prainha PA, com então 29 anos de idade. As amostras foram plainadas e polidas, visando a análise microdensitometrica de raios x. Foram obtidos valores de densidade mínimos, médios e máximos (respectivamente 0,581, 0,84 e 1,077gcm-3). Houve diferença significativa na densidade entre as árvores estudadas. Verificou-se, por meio do perfil densitométrico no sentido medula casca, limites dos anéis de crescimento por zonas fibrosas, com variação da densidade entre o lenho inicial e tardio. Verifica-se que os anéisde crescimento da espécie estudada são distintos e anuais, validando a técnica utilizada.(AU)

Growth ring analysis of Euxylophora paraensis through x-ray microdensitometry

ABSTRACT: Euxylophora paraensis Huber - Rutaceae, popularly known as yellow heart, is a species with a low-density population that has suffered intense exploitation in recent decades. This has led to its inclusion in the IBAMA list of endangered species. This study aimed to evaluate the existence of growth rings and their annuity in five trees of Euxylophora paraensis through the x-ray microdensitometry technique, as well as to compare them using the classical method. Application feasibility of this technique can be deepened through future, broader dendroecological studies, which may better elucidate the understanding of the species population dynamics and promote more sustainable uses. Wood disks were collected from the base of five 29-year-old trees from a planting site in the Curua-Una Experimental Station, located in Prainha, Pará State, Brazil. Samples were polished and sanded for the x-ray microdensitometric analysis. Values of minimum, average, and maximum density (0.581, 0.84, and 1.077gcm-3, respectively) were obtained. There was a significant difference in density between the studied trees. Growth rings boundaries, through densitometric pith-bark profile are demarcated by fibrous zones, with density variation between the early wood and late wood. This study concludes that the growth rings of the studied species are distinct and annual, validating the technique used.

RESUMO: Euxylophora paraensis Huber - Rutaceae, popularmente conhecida como pau amarelo, é uma espécie com baixa densidade populacional e que sofreu intensa exploração nas últimas décadas. Isso levou à sua inclusão na lista do IBAMA de espécies ameaçadas de extinção. O presente estudo objetiva avaliar a existência e anuidade dos anéis de crescimento de cinco árvores de Euxylophora paraensis, por meio da técnica de microdensitometria de Raio-x, e comparar com o uso do método clássico. A viabilidade da aplicação dessa técnica poderá ser aprofundada por meio de futuros estudos dendroecológicos mais amplos, que poderão melhor elucidar a compreensão da dinâmica populacional da espécie e promover usos mais sustentáveis. Coletou-se discos do lenho da base de cinco árvores, provenientes de plantio, na Estação experimental de Curua-Una, em Prainha - PA, com então 29 anos de idade. As amostras foram plainadas e polidas, visando a análise microdensitometrica de raios x. Foram obtidos valores de densidade mínimos, médios e máximos (respectivamente 0,581, 0,84 e 1,077gcm-3). Houve diferença significativa na densidade entre as árvores estudadas. Verificou-se, por meio do perfil densitométrico no sentido medula-casca, limites dos anéis de crescimento por zonas fibrosas, com variação da densidade entre o lenho inicial e tardio. Verifica-se que os anéis de crescimento da espécie estudada são distintos e anuais, validando a técnica utilizada.

Growth ring analysis of Euxylophora paraensis through x-ray microdensitometry / Análise dos anéis de crescimento de Euxylophora paraensis por meio da microdensitometria de raios-x

ABSTRACT: Euxylophora paraensis Huber - Rutaceae, popularly known as yellow heart, is a species with a low-density population that has suffered intense exploitation in recent decades. This has led to its inclusion in the IBAMA list of endangered species. This study aimed to evaluate the existence of growth rings and their annuity in five trees of Euxylophora paraensis through the x-ray microdensitometry technique, as well as to compare them using the classical method. Application feasibility of this technique can be deepened through future, broader dendroecological studies, which may better elucidate the understanding of the species population dynamics and promote more sustainable uses. Wood disks were collected from the base of five 29-year-old trees from a planting site in the Curua-Una Experimental Station, located in Prainha, Pará State, Brazil. Samples were polished and sanded for the x-ray microdensitometric analysis. Values of minimum, average, and maximum density (0.581, 0.84, and 1.077gcm-3, respectively) were obtained. There was a significant difference in density between the studied trees. Growth rings boundaries, through densitometric pith-bark profile are demarcated by fibrous zones, with density variation between the early wood and late wood. This study concludes that the growth rings of the studied species are distinct and annual, validating the technique used.

RESUMO: Euxylophora paraensis Huber - Rutaceae, popularmente conhecida como pau amarelo, é uma espécie com baixa densidade populacional e que sofreu intensa exploração nas últimas décadas. Isso levou à sua inclusão na lista do IBAMA de espécies ameaçadas de extinção. O presente estudo objetiva avaliar a existência e anuidade dos anéis de crescimento de cinco árvores de Euxylophora paraensis, por meio da técnica de microdensitometria de Raio-x, e comparar com o uso do método clássico. A viabilidade da aplicação dessa técnica poderá ser aprofundada por meio de futuros estudos dendroecológicos mais amplos, que poderão melhor elucidar a compreensão da dinâmica populacional da espécie e promover usos mais sustentáveis. Coletou-se discos do lenho da base de cinco árvores, provenientes de plantio, na Estação experimental de Curua-Una, em Prainha - PA, com então 29 anos de idade. As amostras foram plainadas e polidas, visando a análise microdensitometrica de raios x. Foram obtidos valores de densidade mínimos, médios e máximos (respectivamente 0,581, 0,84 e 1,077gcm-3). Houve diferença significativa na densidade entre as árvores estudadas. Verificou-se, por meio do perfil densitométrico no sentido medula-casca, limites dos anéis de crescimento por zonas fibrosas, com variação da densidade entre o lenho inicial e tardio. Verifica-se que os anéis de crescimento da espécie estudada são distintos e anuais, validando a técnica utilizada.

Increase in platinum group elements in Mexico City as revealed from growth rings of Taxodium mucronatum ten.

Tree rings may be used as indicators of contamination events providing information on the chronology and the elemental composition of the contamination. In this framework, we report PGEs enrichment in growth rings of Taxodium mucronatum ten for trees growing in the central area of Mexico City as compared to trees growing in a non-urban environment. Concentrations of PGE were determined by ICP-MS analysis on microwave-digested tree rings. The element found in higher concentrations was Pd (1.13-87.98 µg kg(-1)), followed by Rh (0.28-36.81 µg kg(-1)) and Pt (0.106-7.21 µg kg(-1)). The concentration trends of PGEs in the tree-ring sequences from the urban area presented significant correlation values when comparing between trees (r between 0.618 and 0.98, P < 0.025) and between elements within individual trees (r between 0.76 and 0.994, P < 0.01). Furthermore, a clear increase was observed for rings after 1997, with enrichment of up to 60 times the mean concentration found for the sequence from the non-urban area and up to 40 times the mean concentration for the pre-1991 period in the urban trees. These results also demonstrate the feasibility of applying T. mucronatum ten to be used as a bioindicator of the increase in PGE in urban environments.

Rock outcrops reduce temperature-induced stress for tropical conifer by decoupling regional climate in the semiarid environment.

We aimed to understand the effect of rock outcrops on the growth of Podocarpus lambertii within a microrefuge. Our hypothesis holds that the growth and survival of this species depend on the regional climate decoupling provided by rock outcrops. To test this hypothesis, we characterized the microclimate of (1) surrounding vegetation, (2) rock outcrop corridors, and (3) adjacencies. We assessed population structure by collecting data of specimen stem diameter and height. We also assessed differences between vegetation associated or not with outcrops using satellite imaging. For dendrochronological analyses, we sampled 42 individuals. Tree rings of 31 individuals were dated, and climate-growth relationships were tested. Rock outcrops produce a favorable microclimate by reducing average temperature by 4.9 °C and increasing average air humidity by 12 %. They also reduce the variability of atmospheric temperature by 42 % and air humidity by 20 % supporting a vegetation with higher leaf area index. Within this vegetation, specimen height was strongly constrained by the outcrop height. Although temperature and precipitation modulate this species growth, temperature-induced stress is the key limiting growth factor for this population of P. lambertii. We conclude that this species growth and survival depend on the presence of rock outcrops. These topography elements decouple regional climate in a favorable way for this species growth. However, these benefits are restricted to the areas sheltered by rock outcrops. Although this microrefuge supported P. lambertii growth so far, it is unclear whether this protection would be sufficient to withstand the stress of future climate changes.

No evidence for consistent long-term growth stimulation of 13 tropical tree species: results from tree-ring analysis.

The important role of tropical forests in the global carbon cycle makes it imperative to assess changes in their carbon dynamics for accurate projections of future climate-vegetation feedbacks. Forest monitoring studies conducted over the past decades have found evidence for both increasing and decreasing growth rates of tropical forest trees. The limited duration of these studies restrained analyses to decadal scales, and it is still unclear whether growth changes occurred over longer time scales, as would be expected if CO2 -fertilization stimulated tree growth. Furthermore, studies have so far dealt with changes in biomass gain at forest-stand level, but insights into species-specific growth changes - that ultimately determine community-level responses - are lacking. Here, we analyse species-specific growth changes on a centennial scale, using growth data from tree-ring analysis for 13 tree species (~1300 trees), from three sites distributed across the tropics. We used an established (regional curve standardization) and a new (size-class isolation) growth-trend detection method and explicitly assessed the influence of biases on the trend detection. In addition, we assessed whether aggregated trends were present within and across study sites. We found evidence for decreasing growth rates over time for 8-10 species, whereas increases were noted for two species and one showed no trend. Additionally, we found evidence for weak aggregated growth decreases at the site in Thailand and when analysing all sites simultaneously. The observed growth reductions suggest deteriorating growth conditions, perhaps due to warming. However, other causes cannot be excluded, such as recovery from large-scale disturbances or changing forest dynamics. Our findings contrast growth patterns that would be expected if elevated CO2 would stimulate tree growth. These results suggest that commonly assumed growth increases of tropical forests may not occur, which could lead to erroneous predictions of carbon dynamics of tropical forest under climate change.