Thesis (Ph. D.)--Oregon State University, 2003. / Typescript (photocopy). Includes bibliographical references (leaves 133-142). Also available on the World Wide Web.

Thesis (doctoral)--Universität Bonn, 2005. / Downloaded and printed Sept. 10, 2008. Includes bibliographical references (leaves 52-60). Also available via the internet.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2005. / Thesis documentation sheet inserted. Appendix reproduces four papers and manuscripts, three co-authored with others. Includes bibliographical references. Also partially available electronically via World Wide Web in PDF format; online version lacks appendix.

This thesis consists of three manuscripts describing ecophysiological research on the cyanolichen Lobaria oregana. The first manuscript includes a re-evaluation of the assumptions underlying past estimates of N fixation by this species and provides an estimate of annual N fixation at the Wind River Canopy Crane (WRCC). Based upon litterfall data, canopy biomass data, N content of lichen tissue, and published growth rates, L. oregana fixes 0.4-1.6 kg N₂ ha⁻¹ yr⁻¹. The second manuscript presents a series of physiological response curves and a model of N fixation by L. oregana. Temperature is the most important parameter controlling nitrogenase activity in hydrated thalli. The model is used to predict annual N fixation at the WRCC and at the H.J. Andrews (HJA) Experimental Forest. Lobaria oregana fixes 1.4-1.8 kg N₂ ha⁻¹ yr⁻¹ at the WRCC, and low winter temperatures often inhibit nitrogenase activity. Temperatures at the HJA are slightly warmer during the winter, and L. oregana fixes 2.6-16.5 kg N₂ ha⁻¹ yr⁻¹ depending on its stand-level biomass. The third manuscript investigates the effects of thallus water content, light, and temperature on CO₂ exchange in L. oregana. This species shows a typical photosynthetic response upon rehydration, and like other lichens it becomes light-saturated at low PAR levels. Positive net photosynthesis in L. oregana occurs only between 1-12°C. High respiration rates prevent carbon gain at warmer temperatures. The temperature constraints on carbon gain and nitrogen fixation may explain some of the landscape distribution patterns of L. oregana. / Graduation date: 2002

Thesis (doctoral)--Universität Göttingen, 2004. / Includes bibliographical references (leaves 106-117). Also available in PDF format.

Thesis (doctoral)--Uppsala Universitet, 2003. / Includes bibliographical references (p. 28-33). Downloaded and printed Aug. 26, 2004; also available via the Internet.

Graduation date: 2005

The main aim of this study was to analyse the long-term effects on epiphytic lichen dry mass development, diversity and community structure after exposure to a simulated nitrogen deposition gradient. A whole tree experiment was set up in a boreal forest in the County of Västerbotten in Sweden, whereby 15 trees were artificially irrigated and nitrogen fertilized during seven consecutive years (2006-2012). The treatments were equal to an additional deposition of 0.6, 6, 12.5, 25 and 50 kg N ha-1 yr-1. Branches from the trees were collected in October 2012 and the lichen material was harvested and further analysed during the spring 2013. The results from this study showed that the lichens were directly affected by the long-term increased nitrogen deposition. Generally, lichen dry mass and species richness declined at high nitrogen loads and the initial positive effects of low nitrogen loads reported in a preceding study had thus depressed with time. The results from this study also showed that the composition of the lichen community changed benefitting nitrogen-tolerant species, probably not because of competition but more likely because of nitrogen-sensitive species disappearance. This study strongly indicates that it takes more than a few years to detect changes in lichen communities exposed to enhanced nitrogen loads. In addition low concentrations seem to have a cumulative impact. Consequently, this study stresses the importance of also considering the cumulative effect of low nitrogen loads when determining critical values. The critical load for lichen communities in boreal forests might be below 6 kg N ha-1 yr-1.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2008. / Includes reprints of four papers and manuscripts co-authored with others. Includes bibliographical references. Also partially available electronically via World Wide Web in PDF format; online version lacks reprints of four papers and manuscripts.

Lichen uses - potentials of the European Guideline for mapping lichen diversity David Svoboda My projects had one common feature, namely the application of the European Guideline for mapping lichen diversity as an indicator of environmental stress (Asta et al. 2002). This methodology was developed in an effort to make a standardised protocol for European screening of epiphytic lichens for various purposes. The dissertation is focused on selected topics and the main objectives can be summarised as follows: 1) To evaluate the potential of the LDV method for determination of general air pollution, and the possibility of applying the new methodology in the Czech Republic. 2) To compare results given by the LDV method and the older qualitative method by Hawksworth and Rose (1970). 3) To determine the principal factors influencing the epiphytic lichen distribution in Central European oak forests, and to elucidate possible correlations among natural and human caused environmental factors in a large scale study. 4) To investigate the epiphytic lichens living in temperate oak forests, their features and possible lichenological differentiations; to determine indicative species for old growth forests and natural woodlands under different climatic conditions and human influence in the Central Europe. 5) To determine...