Disturbances are ubiquitous features of most northern forest ecosystems. The subsequent response of plant assemblages on both short (resistance or not) and long term (recolonization or not) will depend on a number of factors operating at several spatial scales. In boreal forest ecosystems, bryophyte assemblages are a conspicuous and species rich group of plants for which these processes are poorly understood. Using a combination of experimental and observational approaches this thesis explores these questions for closed-canopy bryophyte assemblages in relation to a) microtopography (both for the initial and long-term response), b) environmental constrains during post-logging succession and c) disturbance type. My results clearly show that the shade and shelter provided by microtopographic surface structures can increase survival rates of bryophytes following clear-cut logging by decreasing mortality from microclimatic stress and mechanical disturbance. Following clear-cutting, the recovery of forest floor and dead wood living bryophytes seems to be a relatively steady and progressive process without any major bottleneck episodes in the young or semi-mature forest stages with much of the pre-disturbance composition recovered after 50 years. Although boulders were found to increase the initial survival on clear-cuts and hence increase disturbance resistance, we found no evidence that boulders influenced the subsequent recolonization process. Lastly, strong compositional dissimilarities were found in young forests (40 years) following clear-cut logging, wildfire and insect outbreak, indicating divergent trajectories to occur following different disturbances. Hence, early seral stages of forest ecosystems regenerating after natural disturbances seem to compliment young managed forests in maintaining landscape level diversity. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Manuscript. Paper 4: Manuscript.

The population structure of a lichen, Thamnolia subuliformis and a moss, Dicranum elongatum, was examined in northeastern regions of Wapusk National Park. With the use of microsatellite molecular markers, it was reported that the sterile lichen had a level of variation similar to that of a sexually reproducing species. The variation reported for the moss, where sporophytes were not encountered, supported subdivided populations. It was concluded that these species have the genetic resources necessary to adapt to changing environmental conditions. / February 2007

The population structure of a lichen, Thamnolia subuliformis and a moss, Dicranum elongatum, was examined in northeastern regions of Wapusk National Park. With the use of microsatellite molecular markers, it was reported that the sterile lichen had a level of variation similar to that of a sexually reproducing species. The variation reported for the moss, where sporophytes were not encountered, supported subdivided populations. It was concluded that these species have the genetic resources necessary to adapt to changing environmental conditions.

Snowbed vegetation contains both vascular plants and bryophytes. The latest snowbeds cover areas that are of predominantly, if not exclusively, bryophyte flora while the vascular plants are generally confined to the periphery of such late snowbeds. It is hypothesised that the exclusion of vascular flora from the snowbed core is the result of the shortened growing season generated by late-lying snow, which the bryophyte flora is better able to tolerate. The snowbed bryophytes cannot, however, tolerate the competition offered by the vascular flora in the peripheral areas from which they are absent. Data indicate that some of the bryophyte snowbed species are inhabiting optimal conditions in the snowbed core, rather than tolerating sub-optimal conditions. Adaptation and acclimation responses observed in peripheral vascular species indicate that these are inhabiting sub-optimal conditions in the snowbed periphery. The relationship between snow-lie and climate is examined, with to the construction and examination of a second hypothesis that snowbed loyalty in the Scottish Highlands is high, while duration of snow cover is variable. Snow-lie loyalty is the product of prevailing wind conditions, which are persistent and consistent in Scotland leading to consistency in late snowbed location, while the occurrence of mid-winter thaws at all altitudes makes duration of snow cover through accumulated snow depth much more variable. Increased zonal flow in winter has affected snow-lie in the Scottish Highlands, with a slight decrease in snow-lie duration in recent years. It is not clear whether this pattern applies to all altitudes and accumulations at higher levels, especially in the western Highlands, may be increasing as a result of steeper winter-time lapse rates. With late snowbed location varying very little, it is possible that the consequences of global warming may not necessarily mean an extinction of the late snowbed bryophytes in Scotland, which constitute an important part of Britain's montane flora.

The population structure of a lichen, Thamnolia subuliformis and a moss, Dicranum elongatum, was examined in northeastern regions of Wapusk National Park. With the use of microsatellite molecular markers, it was reported that the sterile lichen had a level of variation similar to that of a sexually reproducing species. The variation reported for the moss, where sporophytes were not encountered, supported subdivided populations. It was concluded that these species have the genetic resources necessary to adapt to changing environmental conditions.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2007. / Thesis documentation sheet inserted. Includes appendix of four papers and manuscripts, three co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.

Made available in DSpace on 2014-07-29T16:21:18Z (GMT). No. of bitstreams: 1 Dissertacao Lailah Luvizoto Assad.pdf: 2534568 bytes, checksum: ab2279eb387d185161589f97b4d1fb46 (MD5) Previous issue date: 2010-06-08 / The damage caused by the proliferation of edge in forest cover, referred to as edge effects are extensive, may occur over large spatial scales influencing species composition, structure and ecological processes in boundaries of ecosystems. However, studies have shown highly variable response patterns of the taxonomic group studied in relation to the landscape. In this context, bryophytes are an ideal group for assessing the impacts of habitat fragmentation because of their sensitivity to changes in microclimate resulting from the loss and degradation of habitats. This study aimed to assess how the communities from epiphytes liverworts (Marchantiophyta) respond to forest edges originated of anthropogenic fragmentation and the natural edges in the grassland-forest transitions in the Cerrado. The study areas are located in the Parque Estadual da Serra de Caldas Novas and in surroundings, including Caldas Novas and Rio Quente cities, state of Goiás. We sampled three habitat types: (1) forest valleys on the slopes of the mountain with abrupt transitions to rocky fields, (2) edge (0 to 10 m) and (3) interior (100 to 110 m) of semideciduous forest fragments surrounded by a matrix of grass. These were the three treatments considered in the analysis, designated for: BN (natural edge), BA (anthropogenic edge) and IF (interior of the fragment). Four plots (10´10m) were randomly delimited along transects (10´200m) for each treatment in each area. For the sampling in the plots, were selected all trees with perimeter at breast height (PAP) ≥ 20 cm and with minimum coverage of bryophytes of 300cm2. For the quantitative survey of liverworts the interception line method was utilized. Between vegetation parameters, the number of individual trees had positive relationship with richness and abundance in liverworts, whereas basal area had positive relationship with coverage demonstrating the importance of these parameters in liverworts community struture. The richness of liverworts was higher in natural and anthropogenic edges in relation to the interior of the fragments demonstrating that the type of edges do not seem to influence the richness of the liverworts and this increased richness at the edges may be related with the intermediate disturbance hypothesis. Coverage of liverworts was higher in BN than BA, while the BN had distinct floristic composition of BA and IF, that may reflect the environmental peculiarities (moisture, temperature and solar radiation). The evaluation of edge effects on life forms and preference of habits shows some important trends to understand the responses of the liverworts, mainly due to increased frequency of pendant life-forms with low tolerance to desiccation and higher frequency of epiphytes shadow in natural edges. This indicates that the use of functional groups in monitoring the effects of fragmentation can provide a large generalization for the evaluation of responses the liverworts. / Os danos causados pela proliferação de bordas na cobertura florestal, geralmente designados efeitos de borda, são extensos, podendo ocorrer através de grandes escalas espaciais e influenciar na composição de espécies, estrutura e processos ecológicos nos ecossistemas limítrofes. Apesar disso, os estudos têm demonstrado padrões de respostas altamente variáveis, sendo que as respostas dos organismos podem variar tanto em relação à paisagem quanto ao grupo taxonômico estudado. Neste contexto, as briófitas constituem um grupo ideal para a avaliação dos impactos da fragmentação, devido à sua sensibilidade às alterações microclimáticas resultantes da perda e degradação de habitats. Esse estudo teve o objetivo de avaliar como as comunidades de hepáticas (Marchantiophyta) epífitas respondem às bordas florestais proporcionadas antropicamente e às bordas naturais nas transições campo-floresta no bioma Cerrado. As áreas de estudo estão localizadas no Parque Estadual da Serra de Caldas Novas e no seu entorno, compreendendo as cidades de Caldas Novas e Rio Quente, estado de Goiás. Foram amostrados três tipos de habitats: (1) enclaves florestais nas encostas da serra, com transições abruptas para campos rupestres; (2) borda (0 a 10 metros) e (3) interior (100 a 110 metros) de fragmentos de florestas estacionais circundados por matriz de pastagem. Estes foram os três tratamentos considerados na análise, designados por: BN (borda natural), BA (borda antrópica) e IF (interior do fragmento). Quatro parcelas de 10´10m foram plotadas aleatoriamente ao longo de transectos de 10´200m para cada tratamento em cada área. Para a amostragem nas parcelas, foram selecionadas todas as árvores com perímetro à altura do peito (PAP) ≥ 20 cm e com cobertura mínima de briófitas de 300cm2. Para o levantamento quantitativo das hepáticas foi adotado o método de interceptação de linha. Entre os parâmetros da vegetação, o número de indivíduos arbóreos teve relação positiva com a riqueza e abundância de hepáticas, enquanto que a área basal teve relação positiva com a cobertura, o que demonstra a importância destes parâmetros na estruturação das comunidades de hepáticas. A riqueza de hepáticas foi maior nas bordas naturais e antrópicas em relação ao interior dos fragmentos, o que demonstra que o tipo de borda não parece influenciar na riqueza de hepáticas e esta maior riqueza nas bordas pode estar relacionada à hipótese do distúrbio intermediário. A cobertura de hepáticas foi maior em BN do que em BA, enquanto que as BN apresentaram composição florística distinta da BA e IF, o que pode ser reflexo das peculiaridades (umidade, temperatura e radiação solar) neste ambiente. A avaliação dos efeitos de borda sobre as formas de vida e hábitos de preferência mostra algumas tendências importantes para a compreensão das respostas das hepáticas, principalmente devido a maior frequência de forma de vida pendente com baixa tolerância à dessecação e maior freqüência de epífitas de sombra nas bordas naturais. Isso indica que a utilização de grupos funcionais no monitoramento dos efeitos da fragmentação pode proporcionar uma maior generalização para a avaliação das respostas das hepáticas.

Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-07-04T10:44:35Z No. of bitstreams: 1 hellencassiadossantosgomes.pdf: 4897399 bytes, checksum: 5c2ad21c559297af763a438dc5b1a398 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-08T13:06:11Z (GMT) No. of bitstreams: 1 hellencassiadossantosgomes.pdf: 4897399 bytes, checksum: 5c2ad21c559297af763a438dc5b1a398 (MD5) / Made available in DSpace on 2017-08-08T13:06:11Z (GMT). No. of bitstreams: 1 hellencassiadossantosgomes.pdf: 4897399 bytes, checksum: 5c2ad21c559297af763a438dc5b1a398 (MD5) Previous issue date: 2010-03-12 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Inserido no Complexo da Serra da Mantiqueira, o Parque Estadual do Ibitipoca está localizado entre o município de Lima Duarte e a vila de Conceição do Ibitipoca e preserva um importante remanescente vegetacional que inclui diferentes tipos de fisionomias: Candeial, Campos Encharcados, Floresta Ombrófila Densa Altimontana, Floresta Ombrófila Densa Montana, Campo Rupestre Arbustivo, Campo Rupestre sensu stricto e, em especial, uma área de transição entre os dois tipos de campos rupestres. Os objetivos do presente estudo foram inventariar a riqueza específica de hepáticas e antóceros que ocorrem nas diferentes fisionomias do Parque; analisar as espécies nas diferentes fisionomias e relacioná-las com os tipos de substratos em que ocorrem, acrescentando dados para o conhecimento da brioflora atual de Minas Gerais. Os espécimes foram coletados aleatoriamente, ao longo de trilhas pré-existentes, em diferentes substratos e fisionomias do Parque, no período de maio de 2008 a outubro de 2009. No levantamento realizado, foram encontradas 89 espécies de hepáticas (agrupadas em 17 famílias) e uma espécie de antóceros, sendo 13 espécies (12 espécies de hepáticas e uma, de antóceros) citadas pela primeira vez para o Estado de Minas Gerais. O substrato em que as plantas ocorreram em maior frequência foi tronco de árvore, seguido de tronco de árvore morta ou em decomposição. A fisionomia que apresentou maior riqueza específica foi Floresta Ombrófila Densa Montana. A análise dos padrões biogeográficos indica que a maioria do táxons encontrados apresenta distribuição Neotropical. A distribuição geográfica no Brasil indica que a maioria das espécies ocorre em, praticamente, todas as regiões do Brasil. Dentre as famílias estudadas, Lejeuneaceae apresenta maior diversidade específica. O assinalamento de novas adições de hepáticas e antóceros do Parque Estadual do Ibitipoca para Minas Gerais é umas das evidências da relevância do estudo, que amplia o conhecimento da brioflora do estado e do Brasil. / The Ibitipoca State Park is part of the Serra da Mantiqueira, and is located between the municipality of Lima Duarte and the town of Conceição de Ibitipoca. The Park retains an important vegetation remnant which includes different types of physiognomies: “Candeial”, “Campos Encharcados (wet grasslands)”, “Floresta Ombrófila Densa Altimontana”, “Floresta Ombrófila Densa Montana”, Arbustive “Campo Rupestre”, “Campo Rupestre” sensu stricto, and, specially, a transitional area in which the vegetation is a mixture of the two types of “Campos Rupestres”. The aims of this study were to know the species richness of the liverworts and hornworts that occur in the different physiognomies present at the Park, to analyze the species in the different physiognomies, relating them to the substrate in which they occur, improving data to the knowledge of the actual bryoflora of Minas Gerais. The specimens were collected randomly in different substrates, through previously know tracks, during the period of May 2008 to October 2009. The inventory revealed the occurrence of 89 liverworts species (in 17 families) and one hornwort species in the Park; among these species, 13 are being referred for the first time to Minas Gerais (12 liverwort species, and one hornwort species). The more frequent substrate in which the plants occurred was tree trunks, followed by dead or decayed trunks. The physiognomy that presented the largest specific richness was “Floresta Ombrófila Densa Montana”. The biogeographic patterns of distribution indicated that the majority of the collected taxons have a Neotropical distribution. Concerning to distribution of the species in Brazil, the highest number of species studied can be found in almost all the Brazilian geographic provinces. Among the families studied, Lejeuneaceae presents the highest diversity. The relevance of the study is evidenced by the indication of new occurrences of liverworts and hornworts to Minas Gerais, from the Ibitipoca State Park; this improves the knowledge of the state and Brazil’s bryoflora.

Clear-cut logging is the most widely practised forestry method in Sweden. This often conflicts with nature conservation and leads to issues where economic interests are pitted against ecological values. Bryophytes are a group of organisms commonly used as indicators of change in the environment, and several species of this group are also used as tools for assessing conservation values in the habitats they occur in. These are termed indicator or signal species, as they demand certain prerequisites regarding for example climate or substrate that are characteristic for the specific habitat type. In this thesis, the effects of clear-cut logging on five Red-Listed bryophyte species specialised in old-growth forests were tested, to see if they can survive such an intervention. This was done in ArcGIS, by overlaying layers containing 13 years of species observations from Artportalen.se and spatio-temporally matched clear-cut areas from the Swedish Forest Agency. There were 229 logged areas containing a total of 401 observations of the selected bryophyte species, of which 25 were found post-logging. Additionally, 64 % of the post-logged findings were located within a 10 m buffer strip along the edge of the logged areas. The results provide strong evidence that clear-cut logging does impact these species negatively. At the same time the data suggest that developing adequate mitigation measures, for example retention patches along the edges, and evaluating those already in use, can help these species to some extent, by mitigating the negative impact. This is the most important implication from this study, because forestry will continue to be a necessary contribution to the ongoing transition towards a fossil free society. Therefore, the practice needs to shift towards a more biodiversity-friendly management, where alternative forestry methods that are less destructive, are promoted and used to a wider extent. Furthermore, the weight of these species as indicators of high conservation value for the habitats they grow in requires special caution when planning for logging such areas. Otherwise, there is risk of losing species to regional extinction, with specialist species like the ones in this study being of greatest concern. / Den vanligast förekommande skogsbruksmetoden i Sverige är idag trakthyggesbruket. Denna metod är inte alltid kompatibel med naturvårdsintressen och leder ofta till konflikter mellan ekonomiska och ekologiska värden. En organismgrupp som ofta används som indikatorer på förändringar i naturmiljön är mossor. Flertalet mossarter är dessutom så kallade signalarter, vilket betyder att de kan användas som ett mått på naturvärden i den biotop de förekommer i, då de har artspecifika krav på särskilda förutsättningar, som till exempel klimat och substrat. I den här studien testades därför hur slutavverkning påverkar fem Rödlistade mossarter strikt knutna till äldre kontinuitetsskogar. Syftet var att undersöka om de överhuvudtaget kan överleva ett sådant ingrepp. Detta utfördes genom att analysera rumsligt matchade geodatalager i ArcGIS, innehållande 13 års artobservationer från Artportalen.se samt utförda avverkningar från Skogsstyrelsen. Det fanns 229 avverkade områden med totalt 401 artobservationer, varav 25 var funna efter utförd avverkning. Av dessa 25 fynd var 64 % observerade inom en 10 m bred buffertzon utmed det avverkade områdets kant. Resultaten visar tydligt att slutavverkning påverkar dessa arter negativt, men pekar samtidigt på att utvecklingen av lämpliga metoder för naturvårdshänsyn (till exempel hänsynsytor längs med avverkningsområdenas kantzoner) och utvärdering av de metoder som redan används kan mildra problemet. Detta är därmed den viktigaste slutsatsen från denna studie, då skogsnäringen även fortsättningsvis kommer att vara ett viktigt bidrag till den pågående gröna omställningen och det är därför nödvändigt att främja även andra, mindre destruktiva, skogsbruksmetoder för att bibehålla och stärka ekologiska värden, som biodiversitet. Dessutom bör de här arternas värde som signalarter väga tungt vid planering av avverkning i dessa områden, då de ju visar att habitaten har höga naturvårdsvärden. Annars är det risk att vissa arter dör ut, i synnerhet sådana arter som är specialiserade på de miljöer som är mål för exploatering.

La productivité, la décomposition et le recyclage des nutriments sont faibles dans les polygones de tourbe de l’île Bylot. La présence de la Grande oie des neiges pourrait y modifier ces paramètres, car ses fèces contiennent des nutriments facilement assimilables. Il faut cependant considérer l’abondance des mousses. Le rôle important des mousses dans la dynamique des milieux humides a été confirmé par cette étude. À court terme, elles séquestrent les nutriments ajoutés par les fèces. Les plantes broutées ont accès aux nutriments uniquement lorsque les mousses sont saturées et que les nutriments atteignent leurs racines. La décomposition et le recyclage des nutriments ne sont pas affectés. Il semble donc qu’à court terme, l’effet fertilisant de l’oie n’est visible que sur la croissance des mousses. En résultat secondaire, cette étude a démontré que la technique des marqueurs naturels est la plus appropriée pour estimer la production primaire des mousses dans les milieux humides arctiques. / Productivities, decomposition rates and nutrient turnovers are low in polygon fens of Bylot Island. The Greater snow geese population could modify these parameters since goose faeces contain nutrients that are easily uptaken. However, it is important to consider the moss carpet. This study showed that mosses play an important role on the polygon fen dynamic by sequestrating the nutrients added by goose faeces. Grazed plants were able to uptake nutrients only when the mosses are saturated and consequently, when nutrients reach their roots. The decomposition rates and the turnover of nutrients were not affected by nutrient additions. In addition, in the short-term, it seems that fertilizing effect of geese was visible only on moss growth. As a secondary result, this study showed that innate marker method is the most appropriate to estimate moss primary production in arctic wetlands.