Light spectra distributions were measured in two different montane forests: temperate and tropical. Spectral light measurements were made in different sized canopy gaps in the conifer forest at H. J. Andrews Experimental Forest in Oregon, USA. Researchers at Oregon State University created these gaps of 20 m, 30 m, and 50 m in diameter. In the tropical cloud forest, spectral light measurements were made in two plots that were permanently established at La Mucuy Parque Nacional in Venezuela, in collaboration with researchers at Universidad de Los Andes. In both studies, spectra and distributions of physiologically active light were analyzed: red, far-red, R/FR ratio, and blue light.

Shrub expansion in herbaceous ecosystems is emerging as an important ecological response to global change, especially in mesic systems where increases in canopy biomass are greatest. Two consequences of woody encroachment are increases in belowground resources, such as carbon and nitrogen, and reductions in above-ground resources such as light, which affect diversity, community trajectory, and ecosystem function. My objective was to determine how expansion of the nitrogen-fixing shrub Morella cerifera affected the resource environment across a chronosequence of shrub expansion on a Virginia barrier island. I quantified changes in carbon (C) and nitrogen (N) cycling, canopy structure and understory light associated with M. cerifera expansion. Litterfall in shrub thickets exceeded litterfall for other woody communities in the same region, and due to high N concentration, resulted in a return of as much as 169 kg N ha-1 yr-1 to the soil, 70% of which was from symbiotic N fixation. Litter and soil C and N pools were 3-10 times higher in shrub thickets than in adjacent grasslands. Understory light in shrub thickets decreased to as low as 0.5% of above-canopy light. Sunflecks in shrub thickets were shorter, smaller and less intense than sunflecks in forest understories. However, relative to other shrub species such as Elaeagnus umbellata, M. cerifera was less efficient at intercepting light. Although M. cerifera had the highest leaf area index (LAI) of five shrub species studied, M. cerifera was relatively inefficient at light attenuation due to low levels of branching, steep leaf angles and a relatively shallow canopy. The shift from grassland to shrub thicket on barrier islands, and in other mesic systems, results in a significant change in canopy structure that alters understory resource availability and greatly alters ecosystem function and trajectory.

Nitrogen (N) fertilization due to atmospheric deposition (NDEP ) may explain some of the net carbon (C) sink (0.6-0.7 Pg y-1) in temperate forests, but estimates of the additional C uptake due to atmospheric N additions (∆C/∆N) can vary by over an order of magnitude (5 to 200 ∆C/∆N). High estimates from several recent studies [e.g. Magnani (2007), Nature 447 848-850], deriving ∆C/∆N from regional correlations between NDEP and measures of C uptake (such as eddy covariance -derived net ecosystem production, or forest inventory data) contradict estimates from other studies, particularly those involving 15N tracer applications added as fertilizer to the forest floor. A strong ∆C/∆N effect requires nitrogen to be efficiently acquired by trees and allocated to high C:N, long-lived woody tissues, but these isotope experiments typically report relatively little (~ 20 %) of 15N added is found above-ground, with less than 5 % of the total 15N applied found in wood. Consequently the high correlation-derived ∆C/∆N estimates are often attributed to co-variation with other factors across the range of sites investigated. However, 15N-fertilization treatments often impose considerably higher total N loads than ambient NDEP , while almost all exclusively only apply mineral 15N treatments to the soil, often in a limited number of treatment events over relatively short periods of time. Excessive N deposition loads can induce negative physiological effects and limit the resulting ∆C/∆N observed, and applying treatments to the soil ignores canopy nitrogen uptake, which has been demonstrated in numerous studies. As canopies can directly take up nitrogen, the chronic, (relatively) low levels of ambient NDEP inputs from pollution may be acquired without some of the effects of heavy N loads, with trees obtaining this N before it reaches the soil, allowing canopies to substitute for, or supplement, edaphic N nutrition. The strength of this effect depends on how much N uptake can occur across the canopy under field conditions, and if this extra N supplies growth in woody tissues such as the stem, as well as the canopy. Similarly, such mineral fertilizer isotope trace experiments are also unable to trace N in the decomposing litter and humus layers of the soil, which even under heavy NDEP loading contribute most of the N utilised for forest growth. Recent literature suggests that some organic (early decomposition) forms of N may be taken up by roots. If this litter N is not retained or distributed in the same way as mineral fertilizers, its contribution to plant nutrition and ∆C/∆N may need to be reassessed under nitrogen deposition. We tested some of these assumptions in the nursery and the field. In order to facilitate litter 15N tracing, we conducted an experiment injecting large trees with 15N-NH4NO3 to create 15N-labelled litter, tracing the applied isotope into a full harvest of the canopy. Such labelled litter substitute was used to replace the litter layer in a Sitka Spruce plantation (Picea sitchensis L. (Bong.)), where the fate of this 15N from litter decomposition in the soil system was compared against the fate of 15N in deposition. Similarly, in potted Sitka Spruce saplings, we used combination treatments of 15N-labelled litter, soil-targeted 15N-deposition, and canopy targeted 15N-deposition, investigating 15N return in different age classes of above and below ground biomass. We found that i) 15N recovery in canopies (needles and branches) in our injected trees was almost all of the injected 15N five months after injection, ii) canopy application of NDEP led to 60 % 15N return in above-ground parts of saplings compared to 21 % in soil applications and iii) a litter-derived 15N source was retained 55 % more in topsoil, and 36 % more in roots, than a similar deposition 15N source applied as mineral fertilizer. We discuss the implications of such findings in the context of 15N return in different plant organs and ecosystem pools, seasonal variation in N content, and overall inferences of a forest ∆C/∆N effect. Our results suggest that the total ∆C/∆N effect driven by a high N sequestration from canopy uptake in wood is ~ 114:1, more than double that of 15N tracer experiments but not as high as upper estimates from correlative studies, and that litter-derived organic N is better retained in trees and soils in excess of similar amounts of mineral 15N from deposition. Existing forest 15N-fertilization experiments could under-estimate the overall ∆C/∆N effect of atmospheric N deposition.

Master of Science / Department of Geography / Douglas Goodin / Hyperspectral data has been widely used for estimates of canopy biochemical content over the past decades. Most of these studies were conducted in forests or crops with relatively uniform canopies. Feasibility of the use of hyperspectral analysis in heterogeneous canopies with diverse plant species and canopy structures remains uncertain. Spectral data at the canopy level, with mixed background noise, canopy biochemical and biophysical properties create more problems in spectral analysis than that at the leaf level. Complications of heterogeneous canopies make biochemical retrieval through remote sensing even more difficult due to more uneven spatial distribution of biochemical constituents. The objective of my research was to map canopy nitrogen content in tallgrass prairie with mixed canopies by means of hyperspectral data from in-situ and airborne measurements. Research efforts were divided into three steps: (1) the green leaf area index (LAI) retrieval, given LAI is an important parameter in scaling nitrogen content from leaves to canopies; (2) canopy nitrogen modeling from analysis of in-situ hyperspectral data; and (3) canopy nitrogen mapping based on aerial hyperspectral imagery. Research results revealed that a fine chlorophyll absorption feature in the green-yellow region at wavelengths of 562 – 600 nm was sensitive to canopy nitrogen status. Specific spectral features from the normalized spectral data by the first derivative or continuum removal in this narrow spectral region could be selected by multivariate regression for nitrogen modeling. The optimal nitrogen models with high predictive accuracy measured as low values of root-mean-square error (RMSE) were applied to the aerial hyperspectral imagery for canopy nitrogen mapping during the growth seasons from May to September. These maps would be of great value in studies on the interactions between canopy vegetation quality and grazing patterns of large herbivores in tallgrass prairie.

Many amphibian populations are rapidly disappearing throughout the world. An important issue for ecologists is why some amphibian species are more susceptible to decline than others. Here I present five experiments that compare the performance of an endangered (Rana sevosa) and a common (Rana sphenocephala) frog in changing habitats, to determine why these two species differ in their persistence. I include additional studies investigating the habitat requirements and behavior of R. sevosa. I found that habitat change in the form of canopy closure over breeding ponds negatively affects both species, making them smaller as tadpoles and at metamorphosis. The magnitude of size differences was greater for R. sevosa and this species was less likely to survive in closed canopy ponds. Larval survival was not affected in R. sphenocephala and this is likely a key reason for the persistence of this species in habitats where R. sevosa has been extirpated. The introduction of fish to breeding ponds would also differentially affect the two species. R. sevosa did not display behavioral defenses to the threat of fish predation while R. sphenocephala did. R. sevosa displayed a preference for certain characteristics in its habitat including open canopy ponds, grassy terrestrial habitats and an abundance of burrows. An association with the chemical cues of burrow making organisms suggests that these organisms may be important for R. sevosa. Therefore, specialized habitat requirements and behaviors which may be contributing to its decline. I found some evidence of asymmetric competition in the larval stage with R. sevosa negatively affecting R. sphenocephala. It does not appear that larval competition with R. sphenocephala has contributed to the decline of R. sevosa. The primary difference between the two species was in responses to habitat change. R. sevosa appears to be rigid in its habitat requirements and behavior and its inability to respond and adapt to change is a key component of its rarity. By contrast R. sphenocephala showed an ability to cope with habitat changes. Conservation of R. sevosa will require suitable management of the aquatic and terrestrial habitats, primarily through the instigation of an appropriate fire regime.

A oferta de forragem exerce forte influência sobre o consumo e o desempenho dos animais em pastejo com reflexos na estrutura do dossel e no acúmulo de forragem. O objetivo deste estudo foi avaliar o efeito da oferta de forragem (OF) sobre a capacidade fotossintética foliar e do dossel, o acúmulo de forragem, a estrutura do dossel e a eficiência de pastejo em pastagens de capim-Marandu [Brachiaria brizantha (Hochst ex A. RICH.) STAPF.] sob lotação rotacionada. O experimento foi realizado na Faculdade de Zootecnia e Engenharia de Alimentos da Universidade de São Paulo em Pirassununga SP de dezembro de 2002 a abril de 2004. O delineamento experimental foi o de blocos completos ao acaso com quatro repetições. Os tratamentos foram quatro níveis de OF, 5, 10, 15 e 20 kg massa de forragem 100 kg peso vivo-1 dia-1 (%) em lotação rotacionada com ciclos de pastejo de 35 dias, com 28 dias de descanso e sete de ocupação. As variáveis avaliadas durante a rebrotação foram o índice de área foliar (IAF), a interceptação de luz, a altura média do dossel, a massa de forragem e a fotossíntese foliar. A eficiência de pastejo foi estimada em função do acúmulo de forragem durante a rebrotação e da taxa de desaparecimento de forragem, descontando-se as perdas durante o pastejo. A dispersão dos valores de altura do dossel, medidos no pré-pastejo e no pós-pastejo, permitiu a avaliação da variabilidade espacial da vegetação. Com base na distribuição da luz no perfil do dossel e na fotossíntese foliar, foi desenvolvido um modelo matemático para estimar a fotossíntese do dossel e o acúmulo de forragem. A altura do dossel no pós-pastejo se manteve ao redor de 17 cm para a OF de 5%, enquanto que para as demais OFs houve aumento dos valores ao longo do experimento. A relação entre altura e interceptação de luz pelo dossel foi modificada de 2003 para 2004, de modo que para uma mesma altura, a capacidade de interceptação se tornou maior nos dosséis sob OF de 5 e 10%. A fotossíntese foliar decresceu de maneira linear com o aumento da OF e os valores se situaram entre 28 e 23 µmol CO2 m-2 s-1 em 2003 e entre 27 e 24 µmol CO2 m-2 s-1 em 2004, para as OFs de 5 e 20%, respectivamente. A partir do final das avaliações em 2003, houve decréscimo na taxa de acúmulo de forragem (TAF) para as OFs mais elevadas, condição que se manteve em 2004, com uma taxa média de 49 kg MS ha-1 dia-1. O modelo de fotossíntese de dossel indicou que o máximo acúmulo de forragem foi atingido num IAF médio igual a 3,5, valor abaixo do que seria atingido (~ 4) se a fotossíntese foliar máxima (Amax) não diminuísse com o aumento do IAF. A eficiência de pastejo decresceu com o aumento da OF, atingindo valores máximos de 64% em 2003 e 55% em 2004, nas pastagens sob OF de 5%. Apesar da maior produção de forragem, o consumo total para as OFs de 10, 15 e 20% ficou abaixo dos valores obtidos para a OF de 5%. Houve aumento da variabilidade espacial da vegetação após o pastejo, exceção feita à OF de 10%. A utilização de OFs generosas, principalmente 15 e 20%, com o intuito de maximizar o desempenho animal trouxe conseqüências negativas sobre o potencial fotossintético e sobre o acúmulo de forragem em pastagens de capim-Marandu. Além disso, a eficiência de pastejo foi severamente diminuída e houve aumento considerável na variabilidade espacial da vegetação. / Herbage allowance (HA) has strong influence on intake and animal performance in grazing systems, as it impacts canopy structure and net herbage accumulation. The objective of this study was to assess the effects of HA on leaf photosynthesis, net herbage accumulation, sward structure and grazing efficiency in Marandu palisadegrass pastures [Brachiaria brizantha (Hochst ex A. RICH.) STAPF.] under rotational stocking. The experiment was carried out at Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, Pirassununga SP, from December 2002 to April 2004. The experimental design was a randomised complete block with four replications. Treatments were four levels of herbage allowance, 5, 10, 15, and 20 kg dry matter per 100 kg live weight per day (%) in a grazing cycle of 35 days (28 d of rest and 7 d of grazing). Responses studied during regrowth were leaf area index (LAI), light interception, mean canopy height, herbage mass and leaf photosynthesis. Grazing efficiency was calculated as a proportion of net herbage accumulation as well as of the herbage disappearance rate (minus losses) during the grazing period. The dispersion of sward height values, measured pre- and post-graze, allowed for the evaluation of the spatial variability of the vegetation. Based on the light distribution within the canopy profile and leaf photosynthesis, a mathematical model was developed to estimate canopy photosynthesis and net herbage accumulation. Post-graze canopy height averaged 17 cm for 5% HA, whereas for the other HA levels height increased across grazing cycles. The relationship between canopy height and light interception changed from 2003 to 2004. For the same height, interception increased in the 5 and 10% HA canopies. Leaf photosynthesis decreased linearly with increased HA, due to mutual shading within the canopy. Photosynthetic rates ranged from 28 and 23 µmol CO2 m-2 s-1 in 2003 and from 27 to 24 µmol CO2 m-2 s-1 in 2004, for the 5 and the 20% HAs, respectively. From season-end in 2003, through the winter dry season, net herbage accumulation under high HA decreased, and this persisted through the 2004 grazing season. The model of canopy photosynthesis suggests that maximum herbage accumulation was reached at a 3.5 LAI, lower than what would be reached (~ 4) if the maximum leaf photosynthesis did not decrease with increasing LAI. Grazing efficiency decreased with increased HA, and highest efficiencies were 64% in 2003 and 55% in 2004, in pastures under the 5% HA treatment. Despite the higher forage dry matter production, intake in the 10, 15, and 20% HA pastures was lower than that under 5% HA. Grazing increased the spatial variability of the vegetation, except for the 10% HA. The use of generous HA levels (15 and 20%), although favourable to high animal performance, was detrimental to the photosynthetic capacity and net herbage accumulation in pastures of Marandu palisadegrass. In addition, grazing efficiency was severely reduced and spatial variability was considerably higher under high HA.

A reposição de perfilhos mortos ou consumidos pelo pastejo é ponto chave para manutenção da perenidade e produtividade da pastagem. Dentre outros fatores, a dinâmica com que esse processo ocorre é variável em função das estratégias de manejo utilizadas. Dessa forma, as estratégias de manejo do pastejo afetam a dinâmica do perfilhamento, gerando modificações em densidade populacional de perfilhos e em sua composição, nos padrões de ocupação horizontal da área e na estabilidade da população de perfilhos, características determinantes da perenidade e produtividade da planta forrageira. Com isso, o objetivo com este trabalho foi avaliar a frequência e o tamanho das touceiras, a dinâmica do perfilhamento, a densidade populacional de perfilhos e a participação relativa de perfilhos basais e aéreos na população de plantas de capim-elefante cv. Napier submetido a estratégias de pastejo rotativo de janeiro de 2011 a abril de 2012. Os tratamentos corresponderam a combinações entre duas condições pós- (alturas pós-pastejo de 35 e 45 cm) e duas condições pré-pastejo (95% e máxima interceptação luminosa - IL95% e ILMáx) e foram alocados às unidades experimentais segundo arranjo fatorial 2x2 e delineamento de blocos completos casualizados, com quatro repetições. Foram avaliadas características da estrutura horizontal dos pastos, dinâmica do perfilhamento e população de perfilhos totais e demografia de perfilhos basais e aéreos. Pastos manejados com a meta IL95% apresentaram ocupação mais uniforme da área caracterizada pela maior frequência de touceiras e menor frequência de espaços vazios relativamente àqueles manejados com a meta ILMáx. Independente da meta de IL pré-pastejo, os pastos passaram por um período de adaptação aos tratamentos impostos caracterizado pela redução da variabilidade do perímetro médio das touceiras do início do experimento até o início da primavera. Pastos manejados com a meta ILMáx apresentaram menor índice de estabilidade da população de perfilhos, consequência das maiores taxas de mortalidade relativamente aos pastos manejados com a meta IL95%. A densidade populacional de perfilhos aéreos (DPPa) foi maior que a de perfilhos basais (DPPb) para ambas as metas de IL pré-pastejo. De forma geral, não foi registrada diferença em DPPa entre as metas de IL pré-pastejo, mas a DPPb foi maior nos pastos manejados com a meta IL95%. A estratégia de manejo caracterizada pela meta IL95% favorece menor mortalidade de perfilhos e maior perfilhamento basal que, por sua vez, favorece ocupação mais uniforme da área, sugerindo possíveis benefícios para a habilidade competitiva e produtiva da pastagem. / Replacement of dead or consumed tillers during grazing is a key point for ensuring longevity and productivity of pastures. Among other factors, the dynamics of the tillering process is variable depending on management strategies used. In that context, grazing management strategies affect tillering dynamics causing changes in tiller population density and its composition, patterns of plant horizontal distribution and area occupation and in the stability of tiller population, all important characteristics determining longevity and productivity of forage grass communities. The objective of this study was to evaluate the frequency and size of tussocks, tillering dynamics, tiller population density and the relative contribution of basal and aerial tillers in elephant grass cv. Napier subjected to strategies of rotational stocking management from January 2011 to April 2012. Treatments corresponded to combinations between two post- (post-grazing heights of 35 and 45 cm) and two pregrazing conditions (95% and maximum canopy light interception during regrowth - LI95% and LIMax), and were allocated to experimental units (850 m2 paddocks) according to a 2x2 factorial arrangement in a complete randomised design, with four replications. The following response variables were measured: characteristics of sward horizontal structure, tiller dynamics and population, and demography of basal and aerial tillers. Swards managed with the LI95% target showed a more uniform occupation of the area characterised by higher frequency of tussocks and lower frequency of bare ground areas relat ive to those managed with the LIMax target. Regardless of LI pre-grazing target, swards underwent an adaptation period to treatments imposed characterised by reduction in the variability of the average tussock perimeter from the beginning of the experiment until early spring. Swards managed with the LIMax target had lower population stability index than those managed with the LI95% target, consequence of higher tiller death rates. Population density of aerial tillers (TPDa) was larger than basal tillers (TPDb) for both LI pre-grazing targets. In general, there was no difference in TPDa between LI pre-grazing targets, but TPDb was larger on swards managed with the LI95% target. the management strategy characterised by the LI95% target results in lower tiller death and larger production of basal tillers that, in turn, favours a more uniform occupation of the area, suggesting potential benefits to the competitive and productive ability of pastures.

Na natureza, durante milhares de anos de convivência, gramíneas forrageiras e herbívoros passaram por um processo de co-evolução desenvolvendo múltiplas estratégias de sobrevivência e de adaptação. Práticas de manejo que interferem na forma como a forragem é disponibilizada aos animais (estrutura do dossel forrageiro) podem causar mudanças dos padrões de procura e ingestão de forragem e interferir com o desempenho animal. Nesse contexto, o objetivo deste estudo foi avaliar a estrutura do dossel forrageiro e a taxa de consumo de forragem em pastos de capim-elefante cv. Napier (Pennisetum purpureum Schum.) submetidos a estratégias de pastejo rotativo. O experimento foi conduzido em área da Escola Superior de Agricultura \"Luiz de Queiroz\", Piracicaba, SP, de janeiro de 2011 a abril de 2012. Os tratamentos corresponderam a combinações entre duas condições pós- (alturas pós-pastejo de 35 e 45 cm) e duas condições pré-pastejo (95% e máxima interceptação de luz pelo dossel forrageiro - IL), alocados às unidades experimentais (piquetes de 870 m²) segundo arranjo fatorial 2x2 e delineamento de blocos completos casualizados, com quatro repetições. Foram avaliadas em pré- e em pós-pastejo as seguintes variáveis-resposta: distribuição vertical dos componentes morfológicos da massa de forragem dos pastos, taxa de bocados, massa do bocado, taxa de consumo e valor nutritivo da forragem consumida (composição morfológica e bromatológica de amostras de extrusa).A estrutura do dossel influenciou fortemente a massa do bocado, a taxa de bocados e a taxa de consumo independente de tratamento e época do ano. Em pré-pastejo, apesar de a massa do bocado ter sido maior nos pastos manejados com a meta ILMáx, não houve diferença em taxa de consumo entre as metas de IL avaliadas, resultado da maior taxa de bocados registrada nos pastos manejados com a meta IL95%. Em pós-pastejo a taxa de consumo também não variou entre as metas de IL avaliadas, sendo observados ajustes na taxa de bocados como forma decompensar as variações em massa do bocado. As metas de altura pós-pastejo modificaram a composição morfológica e bromatológica da forragem consumida, as quais variaram também em função da época do ano. De maneira geral, pastos manejados com a meta IL95% e altura pós-pastejo de 45 cm resultaram em maior porcentagem de folhas na extrusa, o que conferiu melhor taxa de consumo e valor nutritivo da forragem consumida pelos animais em pastejo. / In nature, during thousands of year of co-existence, forage grasses and herbivores underwent a co-evolution process that resulted in multiple survival strategies and adaptations. Management practices that interfere with the way forage is presented to animals (sward structure) may cause changes in patterns of search and consumption of herbage, affecting animal performance. The objective of this experiment was to evaluate sward structure and rate of herbage intake of rotationally stocked elephant grass (Pennisetum purpureumSchum., cv. Napier). The experiment was carried out at Escola Superior de Agricultura \"Luiz de Queiroz\", Piracicaba, SP, Brazil, from January 2011 to April 2012. Treatments corresponded to combinations between two post- (post-grazing heights of 35 and 45 cm) and two pre-grazing swards conditions (95% and maximum canopy light interception - LI), and were allocated to experimental units (870 m2 paddocks) according to a 2x2 factorial arrangement in a complete randomised block design, with four replications. The following response variables were evaluated in both pre- and post-grazing conditions: vertical distribution of morphological components of sward herbage mass, bite rate, bite mass, rate of intake and nutritive value of the consumed herbage (morphological and chemical composition of extrusa samples). Sward structure strongly influenced bite mass, bite rate and rate of intake regardless of treatment and season of the year. At pre-grazing, in spite of the larger bite mass on swards managed with the pre-grazing target LIMax, there was no difference in rate of intake between LI targets, consequence of the higher bite rate recorded on swards managed with the pre-grazing target LI95%. At post-grazing, there was no difference in rate of intake between LI targets, with variations in bite rate used to compensate variations in bite mass. Post-grazing targets altered the morphological and chemical composition of the consumed herbage, which also varied with season of the year. Overall, swards managed with the pre-grazing target LI95% and the 45 cm post-grazing height resulted in larger percentage of leaves in the extrusa, favouring higher rates of intake and nutritive value of the herbage consumed.

The epiphytic lichen Usnea longissima is strongly associated with old-growth forests and is declining. Previous studies have documented unimodal relationships between stand density and abundance of U. longissima. The aim of this thesis has been to investigate whether the same relationship is found in Sweden and to determine the optimum level of stand density. The study area (1.4 ha) was divided into a grid with 48 circular plots (10-m radius). Stand density was measured as basal area (m²/ha) using a relascope and abundance of U. longissima was measured as the length of the longest thallus present on the tree nearest the plot center. Usnea longissima was found in 42 plots (mean thallus length of 37 cm). The regression analyses between length of U. longissima and basal area showed that the relationship was not significant (R²=0.082, P=0.066), and tended to be linear rather than unimodal. However, plots with U. longissima had significantly lower basal area (30.4 m²/ha) than plots without the lichen (35.1 m²/ha). The basal area in U. longissima plots was higher than in Norwegian studies, but similar to other Swedish sites. Thus, my results correspond well with earlier studies that have documented higher basal area in U. longissima-locations in Västernorrland than in more oceanic areas in Norway. Thereby a basal area around 27-35 m²/ha seems most favorable for U. longissima in the study area. The lichen cannot develop large populations in dense stands, indicating that management operations to reduce the basal area might be needed in such stands.

Os manguezais estão entre os ecossistemas, biologicamente, mais produtivos e importantes do mundo, fornecendo bens e serviços exclusivos para as sociedades e os sistemas costeiros. Entre suas funções destacam-se a estabilização da linha de costa e a redução do impacto de fenômenos extremos, como em casos de tempestades e furacão. No entanto, esse ecossistema têm apresentado alterações significativas oriundas da influência antrópica no ambiente, que modificam a cobertura vegetal e que, por sua vez, influenciam todo o ecossistema, inclusive nas interações microclimáticas. A pesquisa tem como objetivo avaliar a relação existente entre os controles (estrutura da vegetação, variação da maré e sistemas atmosféricos) e atributos climáticos (temperatura do ar, umidade absoluta do ar, radiação solar global, vento e precipitação) no manguezal localizado na Barra do Ribeira-Iguape/SP. Para isso, instalou-se uma torre microclimática contendo duas estações meteorológicas de forma a obter uma análise da variação dos atributos climáticos acima e abaixo do dossel de manguezal. Além disso, analisaram-se ainda as características estruturais da vegetação do manguezal. Constatou-se um aumento na transmissividade da radiação solar no dossel do manguezal, uma redução no albedo e uma diminuição na interceptação vegetal, que está associada a degradação do bosque, que não possui indivíduos novos que prosperam no ambiente, portanto sem renovação do ecossistema, resultado da presença de macrófitas ao longo da área de estudo. Comprovou-se o importante papel da maré no manguezal, contribuindo com entrada e saída de energia, favorecendo o resfriamento/aquecimento relativo do ambiente. Concluiu-se que, do ponto de vista microclimático, há diferenças significativas entre o que acontece acima e abaixo do dossel no manguezal, com diferenças superiores a 5°C, como no caso da temperatura máxima ou ainda entre a temperatura do solo e do ar com diferenças que ultrapassaram 10°C. É perceptível, nesse nível escalar, o acoplamento entre as escalas climáticas superiores com o nível microclimático. Observou-se como os atributos climáticos se conectam e como as diferenças entre os atributos climáticos ficam evidentes em escalas temporais inferiores. / Biologically, the mangrove ecosystems are among the most productive and important in the world, providing resources and services exclusive to societies and coastal systems. Its functions include the stabilization of the shoreline and reduction the impact of extreme weather events such as in cases of storms and hurricane. However, this ecosystem have been presenting significant changes arising from anthropogenic influence on the environment, modifying the vegetation and that, in turn, influence the entire ecosystem, including the microclimatic interactions. The research aims to assess the relation between controls (vegetation structure, tide variations and atmospheric systems) and climatic attributes (air temperature, absolute humidity, solar radiation, wind and rainfall) in the mangrove on the bar the Ribeira-Iguape/SP. To this end, was installed one microclimatic tower containing two weather stations to obtain an analysis of climatic attribute variations above and below the canopy of mangrove. Moreover, was analyzed the structural features of the mangrove vegetation. It was found an increase in transmissivity of solar radiation in the mangrove canopy, a reduction in albedo and a decrease in vegetable interception. These changes are associated with the degradation of the forest, who do not have new individuals who thrive in the environment, there is no renewal of the ecosystem as a result of the presence of macrophytes in the study area. It was proven the important role of tidal in mangrove areas, contributing with input and output power, favoring the cooling / heating relative on the environment. It was concluded that, from the microclimatic point of view, there are significant differences above and below the mangrove canopy. In the case of the maximum temperature, the differences were greater than 5 ° C and exceed 10 ° C between the air and soil temperature. It is noticeable in this scalar level, the coupling between the upper climatic scales with the microclimate level. Was observed how the climatic attributes are connected and how the differences between the climatic attributes are evident in inferior temporal scales.