Microclimatic gradients may have large influence on individual vital rates and population growth rates of species, and limit their distributions. Therefore, I focused on the influence of microclimate on individual performance and distribution of species. Further, I examined differences in how microclimate affect species with contrasting distributions or different ecophysiological traits, and populations within species. More specifically, I investigated the performance of northern and southern distributed forest bryophytes that were transplanted across microclimatic gradients, and the timing of vegetative and reproductive development among northern, marginal and more southern populations of a forest herb in a common garden. Also, I compared the landscape and continental distributions across forest bryophytes and vascular plants and, thus, their distribution limiting factors at different spatial scales. Lastly, I examined the population dynamics across microclimatic gradients of transplants from northern and southern populations of a forest moss. The effects of microclimatic conditions on performance differed among bryophytes with contrasting distributions. There were no clear differences between northern and southern populations in the timing of development of a forest herb or in the population dynamics of a moss. However, within each region there was a differentiation of the forest herb populations, related to variation in local climatic conditions and in the south also to proportion of deciduous trees. The continental distributions of species were reflected in their landscape distributions and vice versa, in terms of their occurrence optima for climatic variables. The variation in landscape climatic optima was, however, larger than predicted, which limit the precision for predictions of microrefugia. Probably, the distributions of vascular plants were more affected by temperature than the distributions of bryophytes. Bryophytes are sensitive to moisture conditions, which was demonstrated by a correlation between evaporation and the population growth rate of a forest moss. We might be able to predict species’ landscape scale distributions by linking microclimatic conditions to their population growth rates, via their vital rates, and infer larger scale distribution patterns. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p> / EkoKlim

No description available.

Les tourbières ont stocké un tiers du carbone organique des sols mondiaux (C) malgré une superficie ne représentant que 3% de la surface terrestre. Cependant, en réponse aux changements globaux, les tourbières boréales et tempérées, majoritairement dominées par des sphaignes, peuvent être envahies par des plantes vasculaires susceptibles de modifier la dynamique du C dans ces écosystèmes. Cette thèse vise à étudier comment la présence des plantes vasculaires affecte le cycle du C des tourbières à sphaignes. Ces travaux ont porté principalement sur une plante envahissante de nombreuses tourbières, Molinia caerulea, via une étude en mésocosmes. Les expérimentations montrent que les plantes vasculaires sont à la fois favorables à la croissance des sphaignes et à la décomposition des litières. In fine, les résultats montrent que la présence de Molinia caerulea augmente la capacité de stockage du C dans les mésocosmes de sphaignes (30 to 220 gC stock m⁻² an⁻1), probablement liée à la forte productivité racinaire de cette plante. Cependant, cela semble s’opérer au détriment du C déjà stocké dans la tourbe avec une stimulation des microorganismes à travers la production d’exsudats racinaires. Ces derniers semblent également, d’une part promouvoir la consommation du C organique dissous et les émissions de CO₂ et de CH₄ observées en présence de Molinia caerulea, et d’autre part être responsables de la modification de la sensibilité à la température des exports de C via des changements des communautés microbiennes. L’impact de Molinia caerulea sur les microorganismes va aussi altérer ceux impliqués dans le cycle du N et entrainer une diminution des émissions de N₂O. / Peatlands have stored a third of the soil organic Carbon (C) in only 3% of the land area. However, in response to global change, boreal and temperate peatlands may shift from Sphagnum to vascular plant-dominated peatlands that may alter their C-sink function. This thesis aims at providing a better understanding of the vascular plants interactions in a Sphagnum dominated peatland and their implications on the C cycle. This work mainly focus on the invasion of a graminoid plant, Molinia caerulea, through a mesocosm experiment. Results from experiments show that vascular plants are both able to promote the growth of Sphagnum mosses as well as the decomposition of their litter. Molinia caerulea occurrence appears to increase the C sink capacity of Sphagnum peat mesocosms passing of 30 to 220 gC stock m⁻² y⁻1. This capacity of Molinia caerulea to store C is probably due to it high roots productivity. However, it also seems to stimulate the decomposition of ‘old’ C, stored as peat, by stimulating microorganisms activity through roots exudates. These latter also promote the dissolved organic C consumption and CO₂ and CH₄ emissions observed with Molinia caerulea occurrence, as well as the temperature sensitivity of C exports by altering the microbial communities. Molinia caerulea impacts on microorganisms also affect N cycle conducting to a decrease of N₂O emissions in these ecosystems.

<p>One of the main reasons for the massive loss in plant species diversity is the fragmentation of habitats. In Europe, open pastures and meadows are the habitats going through the most changes during the 20th century, according to the agricultural changes. In this study vascular plants were invented at five different islands in the Lurö archipelago, Vänern, Sweden. The aim of the study was to sort out whether the diversity of plants has gone through any changes in abandoned managed grasslands compared to continuous managed grasslands. The aim was also to study if a change in the landscape has made any differences for the species development or decline. The results indicate that the number of vascular plants were significantly lower in the abandoned areas than the still managed areas. Results, only from the field layer, showed same results. There was a significant difference between the number of indicators in managed lands than lands that were abandoned for 30-40 and 100 years ago. A comparison from earlier study, from a time when grazing had just ceased at some islands, showed a significant difference in plant species diversity between the years. Just a few decades can impoverish a plant community that might have taken hundreds or even thousands of years to build up. To preserve the biological diversity formed by human impact, one must continue managing the lands.</p> / <p>En av de största orsakerna till den massiva förlusten av växtarter, är fragmenteringen av habitat. I Europa är öppna naturbetesmarker och ängar de habitat som genomgått de största förändringarna i och med jordbrukslandskapets omstruktureringar under 1900-talet. I den här studien inventerades kärlväxter på 5 olika öar i kulturlandskapet Lurö skärgårds naturreservat. Syftet var att ta reda på hur diversiteten bland kärlväxtarter skiljer sig mellan hävdade gräsmarker och f.d. gräsmarker där hävd upphört och hur ett förändrat landskap spelat roll för artantalets utveckling eller tillbakagång. Resultat visade att antalet kärlväxter var signifikant lägre i marker som slutat hävdas, än marker som fortfarande hävdas. Även jämförelser i enbart fältskiktet visade ett signifikant högre artantal hos välhävdade marker än marker där hävd upphört. Det fanns en signifikant skillnad mellan antalet indikatorarter i marker som var under hävd och marker som slutat hävdas för 30-40 år sedan, kontra 100 år sedan. Vid jämförelser med en tidigare studie, som ägt rum precis efter att hävden upphört på ett flertal lokaler visade resultat att det fanns en signifikant skillnad i artantal mellan de båda åren. På några få decennier kan ett helt växtsamhälle som byggts upp under hundratals eller kanske till och med tusentals år utarmas. För att bevara den biologiska mångfald som formas av en störningsregim beroende av människans inverkan, måste hävd fortsätta kontinuerligt.</p>

The Swedish deciduous forest has been actively replaced by coniferous forest during the last two hundred years. In Färna Ekopark, Västmanland, this trend is being reversed by restorations of deciduous forests through the removal of coniferous trees in mixed forests. This field study investigates how successful these restorations have been for plant diversity and how they were affected by past grazing and the proportion of similar mixed and deciduous forest habitats in thesurrounding landscape. Plant species richness was investigated in 370 1m2-plots distributed over 37 sample areas and the surrounding landscape analyzed in a GIS. Results show that a few years after restoration there was higher plant species richness and lower homogenization, at the site scale, compared to the controls. When the restored sites were divided into two subgroups dependant on age, the 5-6 year old restoration displayed higher plot richness than the 2-4 year old restorations, but were also more homogeneous. Past grazing showed a generally positive effect on plant diversity, and these areas also responded with a larger increase of plant species richness and less homogenous plant populations after restorations compared to areas that had not been formerly grazed. The proportion of similar deciduous and mixed forest habitats (more than 40 % deciduous trees) inthe surrounding landscape showed no effect on the plant diversity of deciduous forests in general, though it did display a weak influence over the plot richness of restored deciduous forests without a history of grazing. When restoring deciduous forests to increase plant diversity it would therefore appear wise to focuson the formerly grazed deciduous forests. To take advantage of the beneficial effects to plot richness restored deciduous forests should have a high degree of deciduous and mixed forests within one kilometer. / Den svenska lövskogen har aktivt ersatts med barrskog under de senaste tvåhundra åren. I Färna Ekopark, Västmanland, försöker man vända denna trend genom att ta bort barrträd i blandskog ochpå så sätt restaurera lövskog. Denna fältstudie undersöker om restaureringarna har gett ökad växtdiversitet och hur restaureringarna har påverkats av tidigare bete samt andelen av liknande bland- och lövskogshabitat i det omgivande landskapet. Växtartantalet undersöktes med 370 1m2-rutor utspridda över 37 områden och det omgivande landskapet analyserades i ett GIS. Resultaten visar att några år efter restaurering hade områdena högre växtdiversitet och artsammansättningen var mindre likformig i jämförelse med kontrollerna. När de restaurerade områdena delades upp i två grupper, i avseende på ålder, uppvisade de 5-6 år gamla restaureringarna högre växtdiversitet i rutorna än de 2-4 år gamla restaureringarna, men artsammansättningen var även mer likformig. Tidigare bete visade en generellt positiv inverkar på växtdiversiteten och dessa områden fick en ännu större uppgång i artrikedom och ännu lägre likformighet i artsammansättningarna efter restaureringarna än de områden som inte hade betats tidigare. Andelen av liknande bland- och lövskogshabitat (mer än 40 % lövträd) i det omgivande landskapet uppvisade ingen effekt på växtdiversiteten hos lövskog generellt, men det fanns en svag påverkan på växtdiversiteten på rutnivå hos restaurerade lövskogar utan tidigare bete. När man restaurerar lövskog för att öka växtdiversiteten verkar det därför bra att fokusera på tidigare betade lövskogar. Om man vill ta tillvara på den positiva påverkan på växtpopulationerna som omgivande landskap kan ha bör restaurerade lövskogar ha en stor andel bland- och lövskog en kilometer runt omkring sig.

One of the main reasons for the massive loss in plant species diversity is the fragmentation of habitats. In Europe, open pastures and meadows are the habitats going through the most changes during the 20th century, according to the agricultural changes. In this study vascular plants were invented at five different islands in the Lurö archipelago, Vänern, Sweden. The aim of the study was to sort out whether the diversity of plants has gone through any changes in abandoned managed grasslands compared to continuous managed grasslands. The aim was also to study if a change in the landscape has made any differences for the species development or decline. The results indicate that the number of vascular plants were significantly lower in the abandoned areas than the still managed areas. Results, only from the field layer, showed same results. There was a significant difference between the number of indicators in managed lands than lands that were abandoned for 30-40 and 100 years ago. A comparison from earlier study, from a time when grazing had just ceased at some islands, showed a significant difference in plant species diversity between the years. Just a few decades can impoverish a plant community that might have taken hundreds or even thousands of years to build up. To preserve the biological diversity formed by human impact, one must continue managing the lands. / En av de största orsakerna till den massiva förlusten av växtarter, är fragmenteringen av habitat. I Europa är öppna naturbetesmarker och ängar de habitat som genomgått de största förändringarna i och med jordbrukslandskapets omstruktureringar under 1900-talet. I den här studien inventerades kärlväxter på 5 olika öar i kulturlandskapet Lurö skärgårds naturreservat. Syftet var att ta reda på hur diversiteten bland kärlväxtarter skiljer sig mellan hävdade gräsmarker och f.d. gräsmarker där hävd upphört och hur ett förändrat landskap spelat roll för artantalets utveckling eller tillbakagång. Resultat visade att antalet kärlväxter var signifikant lägre i marker som slutat hävdas, än marker som fortfarande hävdas. Även jämförelser i enbart fältskiktet visade ett signifikant högre artantal hos välhävdade marker än marker där hävd upphört. Det fanns en signifikant skillnad mellan antalet indikatorarter i marker som var under hävd och marker som slutat hävdas för 30-40 år sedan, kontra 100 år sedan. Vid jämförelser med en tidigare studie, som ägt rum precis efter att hävden upphört på ett flertal lokaler visade resultat att det fanns en signifikant skillnad i artantal mellan de båda åren. På några få decennier kan ett helt växtsamhälle som byggts upp under hundratals eller kanske till och med tusentals år utarmas. För att bevara den biologiska mångfald som formas av en störningsregim beroende av människans inverkan, måste hävd fortsätta kontinuerligt.

What drives species diversity across landscapes is one of the most fundamental questions in ecology. Further, understanding the mechanisms underlying species diversity patterns is important not only for forming and challenging ecological theories but also essential for appropriate landscape management and effective nature conservation. This thesis focuses on patterns of vascular plant, moss and liverwort species richness and composition in relation to water flow in boreal-forest catchments, focusing mostly on riparian zones (RZs), that is terrestrial areas bordering streams and rivers. I addressed some of the most essential questions related to the ecology of riparian vegetation including the role of stream network position, groundwater (GW) flow paths, substrate availability, upland perturbations, and stream restoration. I also investigated how riparian soil processes and habitat properties relate to these factors in order to provide a holistic understanding of riparian dynamics. The results showed that the species richness and composition of riparian vascular plants, mosses and liverworts are strongly influenced by position along the stream network, GW discharge, presence of variable substrates in RZs, and by stream restoration. Generally, more species were found downstream in the network, at sites with inputs of upland GW, sites with high diversity of substrates (e.g., open mineral soil, rocks, stones, wood and bark), and along streams restored after channelization. This thesis also describes how riparian habitat properties responded to position in the landscape and human impacts, thus providing mechanistic links between plant species diversity and riparian processes across spatial scales. These ecological insights are further implemented into numerous recommendations for freshwater and upland management in boreal Sweden. Given that streams and rivers connect landscape elements both longitudinally and laterally I argue that management plans should be designed for entire catchments instead of individual river segments. Ignoring the connectivity of streams as well as the high connectivity of riparian areas to uplands via GW flows may result in failure of restoration, mitigation and/or protection actions. Further, during forestry operations more emphasis should be placed on GW discharge areas along streams and rivers, because they represent important ecological and biogeochemical hotspots in the landscape. The riparian buffers left along streams in boreal catchments affected by forestry are presently insufficiently wide and often uniform in width. This threatens the assemblages of species in GW discharge hotspots and the ecosystem services they provide. Overall, this thesis describes a holistic picture of riparian diversity patterns and riparian processes in boreal landscapes, acknowledges and elaborates on current ecological theories, presenting new patterns in biodiversity, and offers management guidelines.

Orientador: Julio Antonio Lombardi / Banca: Marco Atonio de Assis / Banca: Milton Groppo Junior / Resumo: A Mata da Pavuna é um fragmento de floresta estacional semidecídua em um cânion com afloramento rochoso e solo raso, localizado no município de Botucatu, Estado de São Paulo. Foram amostradas todas as espécies vasculares em estádio reprodutivo e identificadas até o menor nível possível. Foram encontradas 381 espécies em 83 famílias. Fabaceae foi a família com maior número de espécies (44), seguido de Asteraceae (33), Euphorbiaceae (18), Poaceae (17), Malvaceae (14), Bignoniaceae e Solanaceae (12). Em Pteridophyta sensu stricto as famílias mais diversas foram Pteridaceae (oito espécies) e Polypodiaceae (sete). Comparado a outros levantamentos florísticos extensos na Mata Atlântica os resultados ressaltam a elevada diversidade florística local, bem como a presença de espécies típicas de formações xerofíticas sugerindo, inclusive, a ocorrência de um encrave de vegetação seca. Noticiamos também o primeiro registro de Pellaea ovata (Desv.) Weath. (Pteridaceae) para o Brasil / Abstract: The „Mata da Pavuna‟ is a semideciduous seasonal forest fragment located in a canyon characterized by rock outcrops and shallow soil, in municipality of Botucatu, State of São Paulo. We collected all vascular plants in reproductive stage, and identified them to the lowest taxonomic level possible. We found 381 species in 83 families. Fabaceae was the most diverse family with 44 species, followed by Asteraceae (33), Euphorbiaceae (18), Poaceae (17), Malvaceae (14), Bignoniaceae (12) and Solanaceae (12). In the Pteridophyta sensu lato the most diverse families was Pteridaceae (eight species) and Polypodiaceae (seven). Compared to other comprehensive floristic surveys carried out in the Atlantic Forest these results show the high floristic diversity and the presence of typical xerofitic vegetation species, suggesting the presence of an enclave of dry forest. We reported here the first mention of Pellaea ovata (Desv.) Weath. (Pteridaceae) for Brazil / Mestre

Made available in DSpace on 2014-06-11T19:23:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-03-01Bitstream added on 2014-06-13T20:29:29Z : No. of bitstreams: 1 santos_lb_me_rcla.pdf: 1972732 bytes, checksum: 1e73f7d242eda88ec651d632e3d4c8a0 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A Mata da Pavuna é um fragmento de floresta estacional semidecídua em um cânion com afloramento rochoso e solo raso, localizado no município de Botucatu, Estado de São Paulo. Foram amostradas todas as espécies vasculares em estádio reprodutivo e identificadas até o menor nível possível. Foram encontradas 381 espécies em 83 famílias. Fabaceae foi a família com maior número de espécies (44), seguido de Asteraceae (33), Euphorbiaceae (18), Poaceae (17), Malvaceae (14), Bignoniaceae e Solanaceae (12). Em Pteridophyta sensu stricto as famílias mais diversas foram Pteridaceae (oito espécies) e Polypodiaceae (sete). Comparado a outros levantamentos florísticos extensos na Mata Atlântica os resultados ressaltam a elevada diversidade florística local, bem como a presença de espécies típicas de formações xerofíticas sugerindo, inclusive, a ocorrência de um encrave de vegetação seca. Noticiamos também o primeiro registro de Pellaea ovata (Desv.) Weath. (Pteridaceae) para o Brasil / The „Mata da Pavuna‟ is a semideciduous seasonal forest fragment located in a canyon characterized by rock outcrops and shallow soil, in municipality of Botucatu, State of São Paulo. We collected all vascular plants in reproductive stage, and identified them to the lowest taxonomic level possible. We found 381 species in 83 families. Fabaceae was the most diverse family with 44 species, followed by Asteraceae (33), Euphorbiaceae (18), Poaceae (17), Malvaceae (14), Bignoniaceae (12) and Solanaceae (12). In the Pteridophyta sensu lato the most diverse families was Pteridaceae (eight species) and Polypodiaceae (seven). Compared to other comprehensive floristic surveys carried out in the Atlantic Forest these results show the high floristic diversity and the presence of typical xerofitic vegetation species, suggesting the presence of an enclave of dry forest. We reported here the first mention of Pellaea ovata (Desv.) Weath. (Pteridaceae) for Brazil

De nombreuses biomolécules qui constituent les plantes vasculaires ne sont synthétisées que par certains taxons de plantes et ont donc une spécificité chimiotaxonomique. Certaines d'entre elles, tels que les bioterpénoïdes, sont particulièrement résistantes et sont préservées dans les sédiments où elles se transforment en géoterpénoïdes lors de la diagenèse. Ces géoterpénoïdes conservent, partiellement ou totalement, leur spécificité initiale (spécifité paléochimiotaxonomique). Cependant, nos connaissances actuelles en paléochimiotaxonomie botanique, qui permettent d'associer ces biomarqueurs moléculaires à des taxons végétaux, restent encore lacunaires. L'objectif de cette étude est de déterminer la signature moléculaire des familles de conifères fossiles. 68 représentants appartenant aux 7 familles actuelles de conifères ont été artificiellement maturés par pyrolyse en milieu confiné afin de reproduire en laboratoire la transformation des bioterpénoïdes en géopterpénoïdes. Les résultats montrent que les Pinaceae, les Araucariaceae, les Cupressaceae, les Sciadopityaceae, les Podocarpaceae, les Taxodiaceae et les Taxaceae "fossilisés" peuvent se distinguer par la nature et la proportion relative de ces terpénoïdes. De plus, la comparaison des signatures moléculaires ont permis de réaliser des regroupements intergénériques pour chaque famille. Ces regroupements sont comparables avec ceux de la classification phylogénétique. À terme, ces résultats pourront être utilisés dans le cadre d’études paléobotaniques, paléoenvironnementales, environnementales et archéologiques / Many biomolecules that constitute terrestrial vascular plants are only synthesized by a restricted number of plant taxa and have thus a chemotaxonomic specificity. Some of these biomolecules, like the terpenoids, are particularly resistant and can be preserved within sediments where they are transformed into geomolecules during diagenesis. Geoterpenoids keep, partially or totally, their initial specificity (palaeochemotaxonomic specificity). However, our current knowledge in botanical palaeochemotaxonomy, allowing to link these plant biomarkers to plant taxa, remains incomplete. The aim of this study is to determine the molecular signature of fossil conifers. In this objective, 68 species belonging to the 7 extant conifer families were subjected to artificial maturation by confined pyrolysis. This process converts the bioterpenoids included within the plant material into geoterpenoids. The results show that the "fossilized" Pinaceae, Araucariaceae, Cupressaceae, Sciadopityaceae, Podocarpaceae, Taxodiaceae and Taxaceae can distinguished from each other by the nature and the relative proportion of these geoterpenoids. The comparison of these molecular signatures allows to achieve intergeneric groups for each family. These groups are comparable to those of the phylogenetic classification. In the future, these results could be used for palaeobotanical, palaeoenvironmental, environmental and archaeological assessments