<p>The distribution of plant species and functional traits in alpine and arctic environments are determined by abiotic conditions, but also by biotic interactions. In this thesis, I investigate interactions among plants and herbivory effects on plant community composition and plant functional traits in three different regions: Swedish Lapland, Beringia (USA/Russia) and Finnmark (Norway). Reindeer grazing was found to be extensive in southern Lapland and had limited effects on plant community composition and seedling germination. However, reindeer presence was found to influence plant functional traits, particularly in the subalpine birch forest. Tall herbs were lower and had lower SLA when reindeer were present, while small herbs showed an opposite pattern. The contrasting effects on the two herb groups are probably explained by a competitive release for small herbs when the tall herbs are suppressed by reindeer. Rodents had the largest relative impact on plant community composition in southern Lapland and this is consistent with the study from Finnmark, where rodents heavily affected dwarf shrubs on predator-free islands. With no predators present, vole densities increased profoundly and almost depleted some dwarf shrub species. These results support the idea that small mammals in arctic and alpine tundra are controlled by predators (i.e. top-down). However, a decrease in the nutritional quality in a sedge after defoliation gives support for the idea that small mammals are regulated by plant quality (i.e. bottom-up). In Beringia, small and large herbivores differed in the relation to plant community composition, since large herbivores were related to species richness and small herbivores were related to plant abundance. Plant functional traits were related only to large herbivores and standing crop of vascular plants.</p>

The distribution of plant species and functional traits in alpine and arctic environments are determined by abiotic conditions, but also by biotic interactions. In this thesis, I investigate interactions among plants and herbivory effects on plant community composition and plant functional traits in three different regions: Swedish Lapland, Beringia (USA/Russia) and Finnmark (Norway). Reindeer grazing was found to be extensive in southern Lapland and had limited effects on plant community composition and seedling germination. However, reindeer presence was found to influence plant functional traits, particularly in the subalpine birch forest. Tall herbs were lower and had lower SLA when reindeer were present, while small herbs showed an opposite pattern. The contrasting effects on the two herb groups are probably explained by a competitive release for small herbs when the tall herbs are suppressed by reindeer. Rodents had the largest relative impact on plant community composition in southern Lapland and this is consistent with the study from Finnmark, where rodents heavily affected dwarf shrubs on predator-free islands. With no predators present, vole densities increased profoundly and almost depleted some dwarf shrub species. These results support the idea that small mammals in arctic and alpine tundra are controlled by predators (i.e. top-down). However, a decrease in the nutritional quality in a sedge after defoliation gives support for the idea that small mammals are regulated by plant quality (i.e. bottom-up). In Beringia, small and large herbivores differed in the relation to plant community composition, since large herbivores were related to species richness and small herbivores were related to plant abundance. Plant functional traits were related only to large herbivores and standing crop of vascular plants.

The Carex nardina complex is a group of one to three species (C. nardina, C. hepburnii, C. stantonensis) and six taxa of unispicate sedges (Cyperaceae), the taxonomy of which has been controversial since the 1800s. As initial DNA phylogenies suggested that the complex was nested within Carex section Filifoliae and sister to C. elynoides, a species often confused with C. nardina and sympatric with it in the western North American Cordillera, analyses were conducted to determine whether C. hepburnii, C. stantonensis and other infraspecific taxa could be the result of hybridization. Morphometric and molecular analyses found no substantial evidence for hybridization and supported the recognition of no taxon beyond C. nardina. Consequently, this study concludes that the complex comprises a single variable species, Carex nardina, distributed throughout arctic North America south through the western Cordillera to New Mexico with a minor portion of its range in northeastern Russia, northwestern Scandinavia and Iceland.

ABSTRACT A Comparative Study of Three Growing Media and Four Plant Groups Under Extensive Green Roof Conditions in San Luis Obispo, California Todd A. Nelson Green roof growing media and plant species are critical factors when deciding on the best materials for a project. Growing media must be chosen in accordance with load bearing capacities of structures and water requirements of the plant material. Plant species must be able to thrive in the climate of the green roof and withstand a green roof’s harsh environment. The objectives of this research were: (1) to determine which of three extensive green roof growing media support the most growth of Sedum, a proven extensive green roof plant genus; and (2) to determine which of four plant groups provides the most media coverage under extensive green roof conditions. Sedum growing in a granular growing media blend with higher organic matter and larger particles provided more coverage than Sedum growing in a medium with smaller particles with lower organic matter and an experimental foam medium. Sedges covered the soil faster than Sedum, grasses, and Mediterranean species. These results will help green roof designers and landscape architects anticipate the plant growth rates during the first 36 weeks of new projects and choose more effective growing media blends. They can also observe the growth patterns of the plant groups to choose plant material that will achieve the functional objectives of a green roof more efficiently. These results are applicable to green roofs designed for moderate California coastal climates and regions with similar weather conditions.

For over a century, the origins and mechanisms underlying the diversification of the enormous cosmopolitan genus Carex (>2,100 species; Cariceae, Cyperaceae or sedge family) have remained largely speculative. Although its unique morphology (e.g., unisexual flowers, perigynia) clearly indicated it was a natural group, it obscured its relationships to all other Cyperaceae because the morphological gap between it and the rest of the family was so wide. Consequently, no plausible sister group to Carex has ever been proposed. Early molecular analyses narrowed the problem by placing Carex within a strongly-supported clade with the enigmatic monospecific genus Khaosokia, and tribes Dulichieae and Scirpeae (hereafter CDS), a group consisting of 2,250 species, or approximately 41% of all Cyperaceae. However, poor taxonomic sampling and the limited number of molecular markers used in these studies meant that the sister group to Carex remained a mystery. The goals of this thesis were to resolve evolutionary relationships within the CDS clade, to identify the sister group to Carex, and to develop a new natural tribal classification of CDS that could be used in future biogeographic and comparative analyses of Carex and its relatives. Initial phylogenetic analyses using two plastid markers (matK, ndhF) identified seven major CDS lineages, and suggested that Carex could be nested within a paraphyletic Scirpeae. However, backbone support for these relationships was low due to an ancient rapid radiation (~10 million years) followed by long divergence of the seven major lineages (~40 million years). The addition of conventional sequence-based markers from the plastid genome (rps16) and nuclear ribosomal region (ETS-1f, ITS) indicated that a traditional molecular approach would not resolve these key backbone nodes. Consequently, a recently developed flowering-plant-specific anchored enrichment probe kit targeting hundreds of conserved nuclear genes combined with next generation sequencing was used to resolve the CDS backbone. Although the resulting phylogenomic dataset was able to resolve the CDS backbone with high support, the topology and branch lengths only reaffirmed the isolated position of Carex. However, comparative morphological analyses of specimens at key herbaria not only suggested that Sumatroscirpus, a rare genus thought to be endemic to Sumatra, could be sister to Carex, but they also provided an easily accessible site to collect DNA in Northern Vietnam. Subsequent phylogenetic analyses of plastid (matK, ndhF, rps16) and nuclear ribosomal (ETS-1f, ITS) markers strongly supported Sumatroscirpus as the sister to Carex, and molecular dating estimates suggested they shared a common ancestor in the late Eocene (~36 million years ago). Comparative studies and ancestral state estimates of key morphological characters were congruent with this hypothesis, suggesting that the perigynium is not unique to Carex, but in fact a synapomorphy shared with Sumatroscirpus. This means that the initial key innovation in the remarkable diversification of Carex is not the perigynium, but could be the release of mechanical constraints that permitted the evolution of the remarkable morphological diversity of Carex perigynia seen today. A taxonomic revision of Sumatroscirpus revealed that this purportedly monospecific genus actually consisted of four species, and it extended its range over 2,400 km to the north into Northern Vietnam, Myanmar, and Southwestern China. The phylogenetic framework provided by the previous studies enabled a new tribal and generic classification of CDS to be proposed. Seven monophyletic tribes are recognised including four new tribes (Calliscirpeae, Khaosokieae, Sumatroscirpeae, Trichophoreae), and a new genus (Rhodoscirpus). Morphological synapomorphies are identified for all recognized tribes, and a worldwide treatment, including identification keys, is provided for Sumatroscirpus species, CDS genera, and Cyperaceae tribes.

Reclaimed oil sands landscapes are perceived to be low in plant diversity compared with naturally occurring plant communities. Approximately 66 Carex species inhabit the oil sand region. This thesis is unique and represents the first large scale study of Carex establishment on reclaimed oil sands landscapes. Research compared diversity and habitat variables between natural ecosystems and reclaimed landscapes, and examined the colonization mechanism for Carex establishment on reclaimed landscapes (i.e., ingress from adjacent natural ecosystems or emergence from the soil seed bank). Low positive associations between the presence of Carex in natural and reclaimed landscapes, and the presence of species on reclaimed landscapes not accounted for in either the forest or edge plots, suggests Carex established from the soil seed bank and less so from natural ingress. Carex share the same seed dispersal mechanisms as many plants, so the implications may apply to a broader range of plant species.

This thesis is part of Project of the Grant Agency of the Czech Republic No P504/11/1151, focused on the role of plants in the balance of carbon dioxide and the other greenhouse gases produced in the ecosystem of a sedge fen, which is situated on the study site Wet Meadows near Třeboň. The thesis deals with the growth dynamics of the dominant sedge, Carex acuta. The samples were taken using the method of successive harvests near the automatic meteorological station of Czech Globe, Academy of Sciences of the Czech Republic. During the growing season nine harvests were accomplished on 25.3, 15.4, 6.5, 5.6., 9.7., 5.8., 9.9., 21.10., 25.11.. On each date eight replicates were taken, i.e., a total of 72 samples within the vegetation season. The seasonal dynamic of the above ground biomass was compared between C. acuta and the other plant species on the experimental area. Both live and dead biomass, was harvested and subsequently sorted to single botanic species, dried, weighed and the values were processed using the MS Excel tables. The seasonal maximum of aboveground biomass of all plant species (both live and dead parts) was found on 9.7. (1452,72 g.m-2). Among plant species the highest values of aboveground biomass were attained by Calamagrostis canescens (1257,93 g.m-2) and C. acuta (1163,49 g.m-2). C. acuta displayed the highest density of all shoots on 15.4 (300 m-2),and the highest average weight of one shoot. The maximum length of the longest live shoot of Carex acuta was very consistent among the measurememnts.

This thesis is part of Project of the Grant Agency of the Czech Republic No P504/11/1151, focused on the role of plants in the greenhouse gas budget of a sedge fen. The thesis deals with the growth dynamics of the dominant sedge, Carex acuta L., on the study site, Wet Meadows near Třeboň, Czech Republic. The seasonal changes in aboveground biomass were followed using successive harvests during vegetation seasons of 2010 and 2011. The seasonal maximum of aboveground biomass of Carex acuta L. (both live and dead parts) was 321,44 g.m-2 and 357,97 g.m-2 in 2010 and 2011, respectively. The seasonal maximum of total aboveground biomas sof all species was 558,22 g.m-2 and 522,38 g.m-2 in 2010 and 2011, respectively. The seasonal maximum of shoot density was 485 ks.m-2 and 435 ks.m-2 in 2010 and 2011, respectively.

No description available.

The thesis was focused on the microevolutionary mechanisms that contribute to morphological diversity in selected members of the sedge family (Cyperaceae). Natural hybridization, evidenced from both morphological characters and molecular markers, was revealed to be a potentially important source of diversification in the tropical spikerushes of Eleocharis subgenus Limnochloa. High levels of phenotypic plasticity of clonal growth but rare genetic (ecotypic) differentiation among contrasting morphotypes were found in the polymorphic species Carex nigra, which implied that taxonomic splitting of the species was unreasonable.