Araucaria Trees Research Articles

Mineral changes in the rhizospheres of conifer plantations for a weathered subtropical soil

AbstractTree species can have great impacts on soil. Since the rhizosphere is more responsive to external inputs than the surrounding bulk soil, we investigated the rhizosphere effect of the exotic slash pine and the native araucaria in long‐term conifer monocultures in southern Brazil. Araucaria trees in a natural section of a nearby mixed araucaria forest were taken as the control. We assessed physical, chemical, and mineralogical properties of the underlying subtropical highly weathered soil. We did not find rhizosphere effects for most chemical and physical soil attributes, yet principal component analysis clearly distinguished the effects of the exotic and native conifers on rhizosphere properties by separating slash pine cluster from reforested and native araucaria clusters. Reductions in silt and sand contents under slash pine reforestation led to increases in clay and well‐crystallized iron oxides contents. The clay mineralogy comprised kaolinite, mica/illite, and hydroxy‐interlayered minerals, with kaolinite enrichment in the rhizospheres of both araucaria sites, mica/illite depletion in the rhizospheres of both araucaria and pine monocultures, and prevalence of well‐crystallized iron oxyhydroxides in the slash pine rhizosphere. This study demonstrates a tendency toward increasing soil weathering in the conifer monocultures, potential negative impacts of the faster growing slash pine reforestation on soil organic carbon, available P, and total K possibly by mica/illite depletion, while araucaria had lower impacts on soil properties. These results show long‐term potential loss of soil fertility and quality, which should be considered when monitoring soil changes in human modified ecosystems.

Modelling height–diameter relationships in living Araucaria (Araucariaceae) trees to reconstruct ancient araucarian conifer height

AbstractTo reconstruct a fossil forest in three dimensions, an accurate estimation of tree height is crucial. However, modelling the height–diameter relationship of ancient trees is difficult, because the trunks of fossil trees are usually fragmentary, making direct height measurements impossible. One practical approach for reconstructing ancient tree height is to use growth models based on the height–diameter relationships of the nearest living relatives of fossil taxa. Here we apply 19 models to describe height–diameter relationships of living Araucaria trees for establishing appropriate models for ancient Araucariaceae trees. Data come from four living populations of Araucaria: A. bidwillii and A. cunninghamii in Queensland, Australia, and A. cunninghamii and A. hunsteinii in New Guinea. According to an AIC‐based model selection, a power function with an exponent of 0.67 (termed here the modified Mosbrugger model) is found to be the most appropriate for each population and for the entire dataset (157 trees), but normalization constants differ across populations. To find the most appropriate models for the genus Araucaria, 100 random samples (each population generating 25 random samples) from the entire dataset are used. Based on 100 curve fitting results on each model and multiple performance criteria, three median models are generated from the medians of their parameter estimates. Of these, the median 2pPower model works best for Araucaria, but the modified Mosbrugger and Curtis models perform nearly as well. In a case study, we revise tree heights of Upper Jurassic araucariaceous logs in Utah, USA, by applying these three models.

Ecological restoration and protection of remnants are key to the survival of the critically endangered Araucaria tree under climate change

Araucaria angustifolia – ‘araucaria’– is a critically endangered conifer tree of great ecological, economic, and cultural importance occurring in subtropical forests and grasslands in southern Brazil. Using ecological niche modeling we estimated its distribution in the present and future scenarios (2050), assessed sources of uncertainties, evaluated the effectiveness of protected areas, and indicated suitable sites for restoration efforts to maintain viable populations. For this, we generated and compared 11,484 models with different combinations of variables and parameters. The final model included variables related to climate, soil, and topography. The potential distribution of araucaria was estimated to be 489.8 × 10 3km2, with a predicted reduction in 2050 from 45% to 56% (SSP245 and SSP585, respectively). The reduction within remaining habitats is estimated to range from 32% to 44%. Combined, current habitat availability and climate change accounted for a reduction from 70% to 75% of the potential distribution. Only 5% of the current potential distribution is within protected areas, which may be reduced to 1%. In addition, 40% of suitable sites in remaining habitats are not protected, which may reduce to 24–28% in 2050. Restoration efforts may contribute to an increase of 42–45% of the remaining population. We show that estimates of araucaria distribution in the future are variable and dependent on climate projections and scenarios, however, the potential distribution in natural grasslands may remain stable. Coordinated actions involving the protection and restoration of habitats associated with population growth are urgent to improve the persistence of araucaria in the future.

SOIL CHEMICAL ATTRIBUTES RELATIONSHIPS AROUND THE Araucaria angustifolia TREES IN AGROFORESTRY SYSTEMS

This work aimed to understand the relationships between araucaria trees and some abiotic factors (soil type, soil organic C and soil nutrient supply) in agroforestry systems (AFS). Soils of two production areas in south-central region of the state of Parana (Bituruna - B and São Mateus do Sul - M) were characterized and soil chemical attributes were determined in microsites close to araucaria trees. B area presented only “juvenile” trees, while M area was formed by “juvenile” and “adult” trees. According to the multiple linear regression analyses, the soil chemical attributes showed an almost total dependence of the microsites depth. Soil chemical attributes dependence was much more diffuse in relation to the distances from the tree insertion in the soil. The non-metric multidimensional scaling ordination according to soil chemical attributes showed a great overlap of behavior of these tree groups. The chemical attributes comparison generated, to a certain extent, a soil fertility deficiency gradient between the microsites of the three groups of trees (MJ < MA < BJ). AFS with shaded Ilex paraguariensis must consider the replacement of nutrients exported by leaf harvest, which will help in the sustainability of the activity. This includes the environmental services that the AFS promotes by maintaining, or even renewing, of the native trees from the local forest, especially araucaria trees, in a productive system.

COMPARATIVE STUDY OF ALCOHOLIC EXTRACTION OF COMPOUNDS FROM ARAUCARIA ANGUSTIFOLIA: MICROWAVE-ASSISTED EXTRACTION VS. MACERATION EXTRACTION.

Background: The Araucaria angustifolia is a prominent tree species indigenous to the southern regions of Brazil. The tree can be a source of different compounds of interest if properly used. Aims: This research aims to compare the alcoholic extraction of compounds from Araucaria angustifolia using two different methods, microwave-assisted extraction and maceration extraction. Methods: Alcahoolic extractions of compounds from the sawdust of Araucaria angustifolia were performed using microwave-assisted extraction and maceration extraction. The color was observed by eye inspection. The taste was observed by putting the samples into the mouth and tasting it. The olfactive test was conducted at hot and cold temperatures. Results: it was obtained red color solution, both from the bark and from the branch. The intensity of the color changed with the extraction method and time of maceration. The solutions tasted like "green wood". Discussion: MAE and Maceration extraction can provide extracts from the bark and branch of the araucaria tree. There is the possibility that the “green wood” taste of the MAE extract can be changed with the thermal treatment of the wood. Conclusions: microwave-assisted extraction can perform the faster extraction of compounds from Araucaria angustifolia than maceration extraction..

Multiproxy Approach to Reconstruct the Fire History of Araucaria araucana Forests in the Nahuelbuta Coastal Range, Chile

Multiproxy reconstructions of fire regimes in forest ecosystems can provide a clearer understanding of past fire activity and circumvent some limitations of single proxy reconstructions. While inferring fire history from scars in trees is the most precise method to reconstruct temporal fire patterns, this method is limited in Araucaria araucana forests by rot after fire injuries, successive fires that destroy the evidence and the prohibition of sample extraction from living Araucaria trees. In this context, dendrochemical studies in Araucaria trees and charcoal analysis from sediment cores can complement and extend the time perspective of the fire history in the relictual Araucaria-Nothofagus forests of the coastal range. We used dendrochemical, fire scar and charcoal records from the Nahuelbuta Coastal Range (37.8° S; 73° W) spanning the last 1000 years to reconstruct the fire history. The results indicate that periods with higher fire activity occurred between 1400 and 1650 AD. Long-term changes in the fire regime are related to increased climate variability over the last 1000 years, and especially with the arrival of settlers to the area after 1860 CE. The most severe fire events in the Nothofagus and Araucaria forests occurred when suitable fire-prone conditions were superimposed with high human densities.

Can We Predict Male Strobili Production in Araucaria angustifolia Trees with Dendrometric and Morphometric Attributes?

Knowledge of the formation and correlation of reproductive structures with dendro/morphometric variables of the Araucaria angustifolia tree species is a tool for its conservation and viability for sustainable forest management. We counted visually in araucaria trees the number of male strobili in RGB images acquired by Remotely Piloted Aircraft System (RPAs) over forest remnants. The diameter at the breast height (d), total height (h), crown radii (cr), crown base height (cbh), periodic annual increment in d based on increment rolls were measured, and the morphometric indices and crown efficiency were calculated with these variables. The relationships of these variables with male strobili production were analyzed by Pearson’s correlation and multivariate analysis techniques (cluster, factorial analysis, and main components). The morphometric variables correlated with the production of male strobili were d (r = 0.58, p-0.0002), crown diameter (r = 0.62, p < 0.0001), crown area (r = 0.62, p < 0.0001), coverage index (r = 0.51, p-0.001) and slenderness (r = −0.39, p-0.01). We argue that the production of male strobili is related to the vitality, dimension, density, growth space, and position in the stratum of the tree inside the forest, inferring a relationship between reproductive structures with the shape, size, growth space, and tree density. Such aspects shall be considered in future forest management initiatives in Southern Brazil.

Chemical composition of bunya nuts (Araucaria bidwillii) compared to Araucaria angustifolia and Araucaria araucana species

Three of nineteen Araucaria tree species from around the world produce large edible seeds. While composition is established for edible pinhão and piñones nuts from Brazil and Chile, respectively, the first detailed characterisation for the composition of edible Araucaria bidwillii (bunya nut) from Australia is provided. Almost half of the kernel weight is moisture and the main component in the dried kernel is starch. Whilst low in protein and fat, it contains all essential amino acids and half the fatty acids are polyunsaturated (Omega-3 and 6). Bunya nuts are a source of dietary fibre, folate and minerals (Cu, Mn, Fe, Mg), while the nut husks and inner coating are high in phenolics, mainly catechin. The composition supports the Traditional Knowledge of Aboriginal Australians that the bunya nut is an energy dense and nutrient rich food. Similarities in the composition among the three different edible varieties were found, which should assist in developing sustainable value chain propositions via shared knowledge on processing and utilisation.

Demographic dynamics of araucaria trees in forest fragments with different structural conditions

The demographic processes of a tree community, such as recruitment and mortality of individuals, significantly affect the other dynamic and structural events of forests. The objective of this research was to evaluate the recruitment and mortality rates of Araucaria angustifolia (Bertol.) Kuntze in forest remnants in Southern Paraná. Data came from seven permanent sample plots of 1 ha each, installed in 1999 and monitored annually for 14 years. Mortality and recruitment, as well as gain and loss rates of basal area, were obtained for the plots, which represent distinct structural features of the remnants. The data indicated that there is not equilibrium among the rates of mortality and recruitment. In general the rate of recruitment was significantly higher than the rate of mortality. From the seven studied plots only two of them had higher rates of mortality than recruitment. The density of the plots had a direct influence on mortality and an inverse influence on recruitment.

Old‐growth structural attributes associated with the last giant subtropical conifers in South America

AbstractGiant Araucaria trees in Brazilian Atlantic forests today are rare but remain critically important for structuring these ecosystems, providing unique and rare habitat elements that can serve as points of reference for their management. Old‐growth Araucaria trees, with their complex crowns and big trunk cavities, supply more important ecological services than smaller trees with simple crowns. Forest ecology managers lack information on the old‐growth structures of Brazilian Araucaria forest, their ecological importance and their potential societal values and uses. In this study, we investigated old‐growth attributes of Araucaria angustifolia and relate their wide structural variability to ecological management goals. In this study, we used currently available data on the last large old Araucaria trees, as well as our own new records, from large trees of 1.6–3.2 m diameter in the Araucaria forests in southern Brazil. In order to quantify the structural attributes of these remnant trees, their main trunks, any reiterated canopy trunks and trunk cavities were measured for diameters, heights and volumes. These old‐growth trees had an average height of 38.4 m, and total tree volumes ranged from 21.5 to 106.6 m3. The biggest reiterated trunk was 1.1 m in diameter and 17 m long, which is larger than most adult Araucaria trees. Number of cavities and number of reiterated trunks were all significantly related to the diameters of these large remnant Araucaria trees; both features are absent in Araucaria <50 cm in diameter. The maximum diameter and average length of reiterated trunks were correlated with the number and size of trunk cavities. Commercial wood values and uses are limited for all trees with main trunk diameters exceeding 1.5 m due to large internal cavities—however, these rare, relictual old‐growth structures are of high ecological value for the local fauna and flora.

The influence of fire and cattle grazing on Araucaria population structure in forest-grasslands mosaics

Disturbances caused by land management via fire and cattle grazing can alter the population structure of keystone species that change the output of vegetation dynamics. Adult araucaria trees (Araucaria angustifolia) can facilitate the establishment of other woody plants and, thus, influence the expansion of forests over grasslands in the highlands of southern Brazil. Here we aimed to check araucaria population structure under two types of management – with or without fire and grazing– and in three habitat types: forests, shrublands and grasslands. We sampled araucaria populations in 40 transects (100×4 m), half of each located in the forest, and the other half, in variable extensions of shrublands or grasslands. Of the 40 transects, 18 were under management with fire and grazing and 22 in a protected area where the two disturbances are prevented (São Joaquim National Park). Overall, we sampled 339 araucaria seedlings, 59 saplings, 44 juveniles and 128 adults. Population structure differed both among habitats, between types of management, and between the same habitats but under distinct types of management. Population density was 1.4 times higher in areas with fire and grazing than without such disturbances, which was caused mostly by a larger number of seedlings. Under fire and grazing, we found 1.4 times more adults in forests, 5.7 times more seedlings in shrublands and 5.3 times more seedlings in the grassland than in the same habitat but without disturbances. Our results indicate that araucarias reach and germinate under all conditions but rarely surpass the seedling stage in grasslands and shrublands where fire and grazing is used. Consequently, fire and grazing disturbances should slow down forest expansion over shrublands and grasslands. In contrast, when disturbances are barred, araucarias can grow large enough to trigger their facilitative effect and then gear up the pace of forest expansion.

Cold spot microrefugia hold the key to survival for Brazil's Critically Endangered Araucaria tree.

Brazil's Araucaria tree (Araucaria angustifolia) is an iconic living fossil and a defining element of the Atlantic Forest global biodiversity hotspot. But despite more than two millennia as a cultural icon in southern Brazil, Araucaria is on the brink of extinction, having lost 97% of its extent to 20th-century logging. Although logging is now illegal, 21st-century climate change constitutes a new-but so far unevaluated-threat to Araucaria's future survival. We use a robust ensemble modelling approach, using recently developed climate data, high-resolution topography and fine-scale vegetation maps, to predict the species' response to climate change and its implications for conservation on meso- and microclimate scales. We show that climate-only models predict the total disappearance of Araucaria's most suitable habitat by 2070, but incorporating topographic effects allows potential highland microrefugia to be identified. The legacy of 20th-century destruction is evident-more than a third of these likely holdouts have already lost their natural vegetation-and 21st-century climate change will leave just 3.5% of remnant forest and 28.4% of highland grasslands suitable for Araucaria. Existing protected areas cover only 2.5% of the surviving microrefugia for this culturally important species, and none occur in any designated indigenous territory. Our results suggest that anthropogenic climate change is likely to commit Araucaria to a second consecutive century of significant losses, but targeted interventions could help ensure its survival in the wild.

Crown Efficiency and Pine Cones Production for Brazilian Pine (Araucaria angustifolia (Bertol.) Kuntze) in South Brazil

Crown efficiency is a relation of growth with the area tree occupies (available area efficiency). Efficiency is associated with the vertical and lateral expansion capacity of the tree and crown, increase, density and light absorption. Thus, our study aimed to evaluate crown efficiency with pine cones∙tree-1 production and dendro/morphometric variables of individual araucaria trees in three forest sites in south Brazil. In each site of each tree, dendrometric and morphometric variables were measured and increment rolls were taken at the breast height diameter level. Together with these data, the morphometric indexes, annual periodic increment in diameter of the last ten years (APId) and efficiency of the crown as a function of APId by the horizontal projection area of the crown (hpac) and number of pine cones∙tree-1 (np) by hpac were calculated. Crown efficiency was modeled as a function of the independent variables hpac, APId, crown length (cl), crown ratio (cr) and np. The accuracy of the adjustment was evaluated by the statistics of the deviance, Akaike’s information criterion and graph of the residuals. The results show that the number of pine cones∙tree-1 increases with annual periodic increment in diameter and diameter. Crown efficiency decreases with increasing hpac, cl and cr, indicating silvicultural treatments should be performed with the removal of trees of larger diameter and crown size. A higher pine cones production and efficiency correlates with forest growth, shape, competition, sociological position (stratum tree occupies) and density.

The last giant Araucaria trees in southern Brazil

ABSTRACT: Araucaria angustifolia (Bertol.) Kuntze is a native tree species of major importance in southern Brazil. It is a regional symbol due to its iconic shape and stature in the landscape; its wood was once economically important and its seeds are an important source of food for the fauna and are presently used in regional cuisine. Despite its importance and apparent abundance, the species is facing extinction mainly as a result of unregulated exploitation and deforestation. This study catalogued the remaining individuals in order to add to the body of knowledge available on A. angustifolia, a species that has become rare across its historic range. The circumference at breast height (1.30 m), the total height, and the tree volume were measured (3,529 araucarias). We catalogued trees with a large diameter measuring them in loco over three years involving a journey of more than 6,800 km. The volumes of these old trees are very large, ranging from 38.2 m3 to 106.6 m3. The largest A. angustifolia individual is located in the state of Santa Catarina and measures 3.25 m in diameter. The giant araucarias with > 2.00 m in diameter are rare and only 13 individuals could be found in southern Brazil; a priority action at the governmental level is to recognize and preserve these monumental trees and together with a need for a public policy of drawing up specific inventories of large trees.

Overlooked Parrot Seed Dispersal in Australia and South America: Insights on the Evolution of Dispersal Syndromes and Seed Size in Araucaria Trees

While Psittaciformes (parrots and allies) are well recognized as highly-mobile seed predators, their role as seed dispersers has been overlooked until very recently. It remains to be determined whether this role is anecdotic or is a key mutualism for some plant species. We recently found that the large nut-like seeds of the two South American Araucaria tree species (A. araucana in Andean forests and A. angustifolia in Atlantic forests, weighing c. 3.5 and 7g, respectively) are frequently dispersed, and to long distances, by parrots. Moreover, both observational and experimental work demonstrated that dispersed seeds can germinate faster after partial predation by parrots. Here, we hypothesized that a third, even larger-seeded (17.5g) congeneric Australian species (A. bidwillii) is also dispersed by parrots. We surveyed 52 A. bidwillii and 42 A. cunninghamii (a sympatric species with small winged seeds, c. 0.2g) during the seeding period. We found that sulphur-crested cockatoos (Cacatua galerita) consumed large amounts of seeds from all of the A. bidwillii trees surveyed. Cockatoos dispersed ca. 30% of the seeds they removed from the mother tree, carrying the seeds to distant perches for handling or dropped them while flying. Dispersal distances ranged between 10 and 153 m (mean = 61m). Most seeds handled for consumption (93%) were fully eaten but others were dropped intact (3%) or only partially eaten (4%), and germination was confirmed for both intact and partially-eaten dispersed seeds. Moreover, seeds dropped by cockatoos facilitated secondary seed dispersal by conspecifics and another three bird species. We found no evidence of other primary dispersal species for A. bidwillii, while the small, winged seeds of A. cunninghamii were just dispersed through barochory and anemochory. The seed weight of the three Araucaria species dispersed by zoochory is strongly related to the body mass of their main seed-dispersing parrot species. These results support a role for parrots as key dispersers of the three large-seeded Araucaria species around the world, and suggest that large seeds may have evolved–at least partially–as an adaptation that allows trees to attract parrots, satiate them, and benefit from their long-distance seed dispersal services.

Interaction of land management and araucaria trees in the maintenance of landscape diversity in the highlands of southern Brazil.

In the southern Brazilian highlands, pre-Columbian societies created domesticated landscapes through the use and management of forests, including nurse Araucaria angustifolia trees, a common conifer in these regions. Nowadays, local smallholders still use traditional practices, such as burning, to promote vegetation for cattle grazing in highland grasslands. Even though burning is normally of small extent and low frequency, such management can slow down natural forest expansion and contribute to the maintenance of grasslands, by opposing the facilitative effect of nurse araucaria trees. To comprehend the interplay between human cultural management, species interactions and the environment, it is important to better understand how these relations affect diversity and composition. Our goal was to investigate how land management, biotic interactions and abiotic factors affect saplings species richness, abundance and composition. We hypothesized that (1) land management would decrease sapling richness and abundance and change sapling composition, (2) nurse araucaria trees would increase species richness and abundance and change sapling composition, and (3) the interactive effect between land management and nurse araucaria trees would shape sapling richness, abundance and composition. Data were collected in unmanaged and managed conditions, both beneath araucaria crowns and in nearby treeless areas. Our results indicate that abundance and species composition are affected by land management and araucaria crown influence. The highest values of sapling abundance were found beneath crowns in unmanaged areas. Species composition changed between all assessed combinations of land management and crown influence. Our study demonstrates the major roles of land management and facilitation in structuring communities, despite the effects of rock and grass cover. Moreover, our results clarify patterns and processes that may emerge in natural highland grasslands, such as the conversion of grasslands into forests and the loss of cultural landscapes when the main local management actions are excluded.

Domesticated Landscapes in Araucaria Forests, Southern Brazil: A Multispecies Local Conservation-by-Use System

Araucaria forest is a sub-tropical component of the Atlantic Forest Biome, occurring between 18o S and 30o S latitude, and 500 to 1800 m altitude in Southern and Southwestern Brazil and Northwestern Argentina. In recent history (20th century), this forest has undergone non-sustainable exploitation and reduction in area dedicated to agricultural and forestry use. However, smallholders continue using several resources from this forest, even adapting management systems. The main system is geared towards the production of yerba mate (Ilex paraguariensis) under Araucaria trees (Araucaria angustifolia), which holds economic, cultural and social relevance for thousands of farmers. Seeking evidence of domestication and conservation of the resources managed in this system, we compared different landscapes on the Northern Plateau of Santa Catarina in Southern Brazil. Focusing on three species – yerba mate, Araucaria and caraguata (Bromelia antiacantha) – we characterized management practices (interviews and guided tours), demographic structure (permanent plots in farming zones and in a protected area) and genetic diversity in populations from farming zones and from a protected area. Demographic structure and genetic diversity from different landscapes were compared to evaluate the system potential for conservation. The results indicated that the three species are intentionally promoted with practices of protection, transplanting and/or selection, in different ways and with different functions (caraguata hedges, yerba mate harvesting and collection of pinhoes – seed-like nuts of araucaria). Landscapes are managed for yerba mate harvesting and cattle raising, for both economic and cultural reasons, with a consequent reduction in the density of most other plant species. In all cases the genetic diversity of the species was high for most of the sampled properties, and the set of farmers’ populations did not differ from the protected area. The set of populations of each species operates as a metapopulation and local management practices contribute to conservation. Thus, management systems and practices conducted by farmers maintain the landscape with productive forest fragments, favoring the conservation-by-use of these species. The system requires these management practices, which bring about changes in various species and are motivated by cultural and economic factors, in order to maintain the domestication of these

Long-term vegetation, climate and ocean dynamics inferred from a 73,500 years old marine sediment core (GeoB2107-3) off southern Brazil

Long-term changes in vegetation and climate of southern Brazil, as well as ocean dynamics of the adjacent South Atlantic, were studied by analyses of pollen, spores and organic-walled dinoflagellate cysts (dinocysts) in marine sediment core GeoB2107-3 collected offshore southern Brazil covering the last 73.5 cal kyr BP. The pollen record indicates that grasslands were much more frequent in the landscapes of southern Brazil during the last glacial period if compared to the late Holocene, reflecting relatively colder and/or less humid climatic conditions. Patches of forest occurred in the lowlands and probably also on the exposed continental shelf that was mainly covered by salt marshes. Interestingly, drought-susceptible Araucaria trees were frequent in the highlands (with a similar abundance as during the late Holocene) until 65 cal kyr BP, but were rare during the following glacial period. Atlantic rainforest was present in the northern lowlands of southern Brazil during the recorded last glacial period, but was strongly reduced from 38.5 until 13.0 cal kyr BP. The reduction was probably controlled by colder and/or less humid climatic conditions. Atlantic rainforest expanded to the south since the Lateglacial period, while Araucaria forests advanced in the highlands only during the late Holocene. Dinocysts data indicate that the Brazil Current (BC) with its warm, salty and nutrient-poor waters influenced the study area throughout the investigated period. However, variations in the proportion of dinocyst taxa indicating an eutrophic environment reflect the input of nutrients transported mainly by the Brazilian Coastal Current (BCC) and partly discharged by the Rio Itajaí (the major river closest to the core site). This was strongly related to changes in sea level. A stronger influence of the BCC with nutrient rich waters occurred during Marine Isotope Stage (MIS) 4 and in particular during the late MIS 3 and MIS 2 under low sea level. Evidence of Nothofagus pollen grains from the southern Andes during late MIS 3 and MIS 2 suggests an efficient transport by the southern westerlies and Argentinean rivers, then by the Malvinas Current and finally by the BCC to the study site. Major changes in the pollen/spore and dinocyst assemblages occur with similar pacing, indicating strongly interlinked continental and marine environmental changes. Proxy comparisons suggest that the changes were driven by similar overarching factors, of which the most important was orbital obliquity.

INFLUÊNCIA DA POSIÇÃO SOCIAL NAS RELAÇÕES MORFOMÉTRICAS DE <i>Araucaria angustifolia</i>

http://dx.doi.org/10.5902/1980509821116As relações morfométrias permitem descrever dimensões das árvores sem o prévio conhecimento da idade, auxilia no planejamento florestal e na execução de atividades silviculturais, principalmente quando se deseja tornar sustentável o uso das florestas. Com esse propósito, o objetivo do presente estudo foi modelar e comparar as relações morfométricas de árvores de araucária que crescem em posição social dominante, codominante e dominada em remanescente florestal nativo, localizado no município de Lages - SC. Um total de 294 árvores distribuídas em classes de DAP foi selecionado intencionalmente no interior da floresta. De cada árvore foi medido o DAP, altura total, altura do fuste, diâmetro de copa sob oito raios, bem como a classificação quanto à posição social. Modelos de regressão linear simples e múltipla foram empregados para descrever a relação h/d, proporção de copa e formal de copa em função do diâmetro a altura do peito na forma simples, quadrática, cúbica, inversa e logarítmica. A análise de covariância com variáveis dummy para descrever a posição social foram usadas para testar o paralelismo e inclinação das regressões indicando a necessidade ou não do emprego de regressões independentes. Os resultados indicaram que, mesmo com grande variabilidade na forma e dimensão das copas decorrente do processo de crescimento e de competição, as relações morfométricas de araucária podem ser estimadas com precisão por modelos de regressão. A relação h/d, proporção de copa e formal de copa pode ser descrita por modelo individual para posição social dominante, codominante e dominada, ou alternativamente por modelo único, com a utilização de variáveis dummy que diferenciam o estrato dominado no modelo de relação h/d e de formal de copa. Para a proporção de copa existe diferença de dimensões das árvores dos três estratos sociais, sendo necessário utilizar uma variável de classificação dummy para cada caso ou os modelos individuais.

DIOECY EFFECT ON GROWTH OF PLANTED Araucaria angustifolia Bert. O. Kuntze TREES

ABSTRACT The aim of the study was to evaluate the influence of dioecy on the growth in diameter at breast height (DBH), individual basal area, total height and individual volume of planted Araucaria angustifolia trees. The data came from 60 trees (30 male trees and 30 female trees) sampled from a 30-year-old plantation in Paraná State. Complete stem analysis was used to recover historical tree growth. The Chapman-Richards model was fitted in order to represent the growth and yield of the dendrometric variables for female and male Araucaria trees. Weighted non-linear least squared method was used in the fitting process and the inverse variance was used as weight to solve the problem of heteroscedasticity. The test to verify the equality of parameters and the identity of non-linear regression models proposed by Regazzi (2003) was used to test the influence of dioecy on growth. Dioecy significantly influenced the growth of Araucaria, and female trees have higher growth in diameter, individual basal area and individual volume, while male trees showed better height development. The asymptotic coefficient of the Chapman-Richards model showed that male trees have a higher asymptotic height than female trees.