Conservation biologists often use biological indicators to measure and monitor changes in biological diversity. This study examines butterflies as indicators using a gradient-based study approach. The urban gradient was characterized by Environmentally Sensitive Policy Areas (ESPAs), urban parks, golf courses, residential areas, and industrial areas. This thesis has been divided into two separate chapters. Chapter 1 summarizes an extensive review of existing data on butterfly presence/absence in the Region of Waterloo to determine what species are relatively uncommon or rare in the Region and examine how butterfly presence/absence has changed over the last 80 year. Each butterfly species that occurs in the region was assigned a regional status which resulted in the identification of 46 uncommon and rare species. Chapter 2 examines changes in butterfly abundance and diversity along a gradient of urbanization to determine how different land uses are potential affecting butterfly communities. Transects, 500 meters in length, were established at fifteen sites, each of which represented a land use within the urban gradient identified. Each transect was walked once a week for a total of 28 weeks over two years (2009 and 2010). Overall butterfly richness was observed to be highest within ESPAs, followed by urban parks and industrial areas and lowest within golf courses and residential areas. Shannon diversity scores were compared using a Kruskal Wallis test and indicated that species richness and evenness was significantly different between ESPAs and urban parks and compared to the remaining land uses, while species richness and evenness was not significantly different among residential areas, golf courses, and industrial areas in either 2009 or 2010. Significant differences in species richness and evenness was observed across the same land uses in 2009 and 2010 for all types except residential areas. Overall butterfly abundance was observed to be highest in industrial areas and lowest within golf courses and residential areas, a trend which was observed in both 2009 and 2010. Abundance was observed to be heavily influenced by counts of two non native species- the cabbage white (Pieris rapae) and European Skipper (Thymelicus lineola). ESPAs were identified as 1) supporting the most diverse butterfly community out of the 5 land uses examined and 2) providing habitat for the highest number of rare and uncommon species, indicating that current regional policies in place for protecting rare species are effective. Through an extensive literature review it was concluded that butterflies are effective indicators in temperate regions within a small geographic area such as the Region of Waterloo. Therefore it is expected that the results of this study indicate how other terrestrial taxonomic groups, which are known to show a similar response to urbanized land uses, may be impacted by urbanization in the Region. It is anticipated that the results of this study may be used to guide urban land use planning as it identifies rare and uncommon butterfly species within the region as well as what land uses need habitat enhancement to support more diverse communities.

Conservation biologists often use biological indicators to measure and monitor changes in biological diversity. This study examines butterflies as indicators using a gradient-based study approach. The urban gradient was characterized by Environmentally Sensitive Policy Areas (ESPAs), urban parks, golf courses, residential areas, and industrial areas. This thesis has been divided into two separate chapters. Chapter 1 summarizes an extensive review of existing data on butterfly presence/absence in the Region of Waterloo to determine what species are relatively uncommon or rare in the Region and examine how butterfly presence/absence has changed over the last 80 year. Each butterfly species that occurs in the region was assigned a regional status which resulted in the identification of 46 uncommon and rare species. Chapter 2 examines changes in butterfly abundance and diversity along a gradient of urbanization to determine how different land uses are potential affecting butterfly communities. Transects, 500 meters in length, were established at fifteen sites, each of which represented a land use within the urban gradient identified. Each transect was walked once a week for a total of 28 weeks over two years (2009 and 2010). Overall butterfly richness was observed to be highest within ESPAs, followed by urban parks and industrial areas and lowest within golf courses and residential areas. Shannon diversity scores were compared using a Kruskal Wallis test and indicated that species richness and evenness was significantly different between ESPAs and urban parks and compared to the remaining land uses, while species richness and evenness was not significantly different among residential areas, golf courses, and industrial areas in either 2009 or 2010. Significant differences in species richness and evenness was observed across the same land uses in 2009 and 2010 for all types except residential areas. Overall butterfly abundance was observed to be highest in industrial areas and lowest within golf courses and residential areas, a trend which was observed in both 2009 and 2010. Abundance was observed to be heavily influenced by counts of two non native species- the cabbage white (Pieris rapae) and European Skipper (Thymelicus lineola). ESPAs were identified as 1) supporting the most diverse butterfly community out of the 5 land uses examined and 2) providing habitat for the highest number of rare and uncommon species, indicating that current regional policies in place for protecting rare species are effective. Through an extensive literature review it was concluded that butterflies are effective indicators in temperate regions within a small geographic area such as the Region of Waterloo. Therefore it is expected that the results of this study indicate how other terrestrial taxonomic groups, which are known to show a similar response to urbanized land uses, may be impacted by urbanization in the Region. It is anticipated that the results of this study may be used to guide urban land use planning as it identifies rare and uncommon butterfly species within the region as well as what land uses need habitat enhancement to support more diverse communities.

Human alteration of the global nitrogen (N) cycle has had major impacts on naturally N-limited ecosystems worldwide. Peatlands, dominated by peat mosses, Sphagnum species, represent one such sensitive ecosystem. I have studied how this ecosystem is affected by increased N availability, using a small-scale N fertilization experiment in combination with a gradient study of three peatlands with varying N deposition. I found both in the experiment and in the gradient a similar pattern of Sphagnum decline accompanied by an increase of vascular plants associated with enhanced N supply. For one common Sphagnum species - both in the experiment and in the gradient study - I also found an identical, linear increase in soluble amino acid N (NAA) accumulation. As soluble amino acids function as N storage compounds among Sphagna, NAA is a suitable measure for Sphagnum N status, and indicates accumulation of excess N not used for growth. My results show that NAA can be used as a sensitive indicator to signal N pollution before the slow, and gradual, regime shift from Sphagnum to vascular plant dominance is visible. In an N-uptake experiment using Sphagnum specimens from the three peatlands varying in N deposition, I found a reduced N-uptake by both investigated Sphagnum species from a high N deposition site, in south-western Sweden. This potential of Sphagna to adjust to high N loads through N uptake regulation will, however, not prevent tissue N accumulation, and as a result a shift from Sphagnum to vascular plant dominance. In general I found similar patterns of N induced changes both in Sphagnum tissue chemistry and vegetation structure in the experiment and along the gradient study. Thus, I conclude that long-term, small-scale field experiments seem to offer reliable estimates of both the direction and strength of key vegetation responses in Sphagnum dominated peatlands. This is likely related to the key role of Sphagna as ecosystem engineers. In the experiment I found a marked time lag in vegetation response to N application treatments. The closed Sphagnum carpet did not collapse until after eight years of continuous treatments. Another result was that dwarf shrubs, e.g. cranberry Vaccinium oxycoccos, first increased, but later declined due to severe attacks by fungal diseases. One important conclusion is that long-term, manipulative field experiments are necessary for our ability to understand how ecosystems will respond to environmental change.

As the climate warms, Arctic bumblebee species face the loss of habitat and must deal with increased competition from southern species tracking their thermal and habitat niches north, for example Bombus terrestris. Previous studies demonstrate that bumblebees follow Bergmann’s rule, i.e., larger body sizes at higher latitudes, despite bumblebees not being considered truly ectothermic, as they can generate heat through muscular activity (i.e., beating their wings). This study seeks to confirm and understand the relationship between body size and temperature using an elevational gradient as a proxy for climate. In this study, I examined 13 plots (420-1164 m.a.s.l.) set along the 3.4 km transect up the slope of Mt. Nuolja in Abisko National Park, Sweden. For body size, I chose to use the commonly accepted proxy distance between the base of the wings (i.e., intertegular distance). For temperature, I chose the mean temperature at time of visitation. Results show that climate is a significant explanatory variable for bumblebee body size, with an overall increasing body size with increasing elevation (i.e., colder climate), although most of the variance is explained by caste, i.e., queens having a larger body size than workers. Body size also shows some correlation with day of capture, which can be explained by changes in environmental conditions (e.g., temperature, flowering plant species) during the growing season experienced by the different emerging times for the castes. Given that caste was the most useful explanatory variable for body size, future studies could look at a larger environmental gradient, for example, by sampling at multiple locations along the entire Scandes mountain range to see if the effects found are localized. Further, specific habitat and specific traits of preferred plants may also help to elucidate body-size differences between species and castes. For example, many bumblebee species’ castes emerge at a specific time of year when only certain flowering plant species in specific habitats are available. This important research would also help to illuminate whether bumblebees and the species of plants they pollinate remain synchronous as climate warming accelerates. Nevertheless, my results show an overall positive relationship between bumblebee body size and elevation, indicating that a warming climate will result in reduced body sizes among bumble bee species. Future studies will have to investigate what consequences this will have for Arctic bumblebee populations – and for the plants that rely on bumblebee visits for their pollination.

As the climate warms, Arctic bumblebee species face the loss of habitat and must deal with increased competition from southern species tracking their thermal and habitat niches north, for example Bombus terrestris. Previous studies demonstrate that bumblebees follow Bergmann’s rule, i.e., larger body sizes at higher latitudes, despite bumblebees not being considered truly ectothermic, as they can generate heat through muscular activity (i.e., beating their wings). This study seeks to confirm and understand the relationship between body size and temperature using an elevational gradient as a proxy for climate. In this study, I examined 13 plots (420-1164 m.a.s.l.) set along the 3.4 km transect up the slope of Mt. Nuolja in Abisko National Park, Sweden. For body size, I chose to use the commonly accepted proxy distance between the base of the wings (i.e., intertegular distance). For temperature, I chose the mean temperature at time of visitation. Results show that climate is a significant explanatory variable for bumblebee body size, with an overall increasing body size with increasing elevation (i.e., colder climate), although most of the variance is explained by caste, i.e., queens having a larger body size than workers. Body size also shows some correlation with day of capture, which can be explained by changes in environmental conditions (e.g., temperature, flowering plant species) during the growing season experienced by the different emerging times for the castes. Given that caste was the most useful explanatory variable for body size, future studies could look at a larger environmental gradient, for example, by sampling at multiple locations along the entire Scandes mountain range to see if the effects found are localized. Further, specific habitat and specific traits of preferred plants may also help to elucidate body-size differences between species and castes. For example, many bumblebee species’ castes emerge at a specific time of year when only certain flowering plant species in specific habitats are available. This important research would also help to illuminate whether bumblebees and the species of plants they pollinate remain synchronous as climate warming accelerates. Nevertheless, my results show an overall positive relationship between bumblebee body size and elevation, indicating that a warming climate will result in reduced body sizes among bumble bee species. Future studies will have to investigate what consequences this will have for Arctic bumblebee populations – and for the plants that rely on bumblebee visits for their pollination.

Die Rotbuche (Fagus sylvatica L.) ist die bestimmende Baumart der potentiell natürlichen Vegetation in den Wäldern Mittel- und Westeuropas die ökonomisch bedeutsamste Laubbaumart Deutschlands. Obwohl diese spät-sukzessionelle Baumart über eine hohe physiologische Toleranz gegenüber einem weiten Spektrum klimatischer Wuchsbedingungen verfügt, wird die Buche gegenüber anderen temperaten Laubbaumarten als relativ trockensensitiv eingeschätzt. Da im Zuge des globalen Klimawandels mit einer Verschlechterung der klimatischen Wasserbilanz und mit einer Zunahme sommerlicher Trockenperioden gerechnet wird, wird die zukünftige Rolle der Rotbuche in der europäischen Forstwirtschaft derzeit intensiv diskutiert. Diese Studie hatte zum Ziel, hydrologische und klimatische Einflüsse auf die Produktivität und die Vitalität der Rotbuche zu untersuchen. Hierdurch sollen grundlegende Mechanismen der Trockenstressantwort bei dieser trocken-sensitiven Art identifiziert, und Rückschlüsse auf zukünftige Klimaantworten von Buchenbeständen ermöglicht werden. Zu diesem Zweck wurde die ober- und unterirdische Biomasseproduktion von 12 Buchenaltbeständen im Norddeutschen Tiefland entlang eines natürlichen Niederschlagsgradienten (543-816 mm a-1) auf einheitlichem geologischen Substrat ermittelt. Um den zusätzlichen Einfluss der Wasserspeicherkapazität der Böden zu berücksichtigen, wurden Paare von Buchenbeständen untersucht, die unter nahezu identischen klimatischen Bedingungen, jedoch auf Böden unterschiedlicher Textur (sandige versus lehmig-sandige Böden) stockten. Einflüsse der Wasserverfügbarkeit und klimatischer Variationen auf das Wachstum wurden untersucht unter Berücksichtigung (i) der gesamten ober- und unterirdischen Biomasseproduktion, (ii) der Dynamik von Ressourcen-Allokation und Kohlenstoff-Partitionierung, sowie (iii) der Morphologie wasseraufnehmender und -abgebender Oberflächen. Unerwarteterweise zeigte sich die gesamte Produktivität von Buchen-Altbeständen nur geringfügig von Veränderungen der hydrologischen Regime entlang des Gradienten beeinflusst. Trotz deutlicher Unterschiede in der jährlichen Wasserverfügbarkeit nahmen die oberirdische und die gesamte Biomasseproduktion auf den trockeneren Flächen des Transektes nicht ab. Allerdings führten ausgeprägte früh-sommerliche Wasserdefizite (in den Monaten Juni und Juli) zu deutlichen Einbußen der oberirdischen Biomasseproduktion, und insbesondere der Stammholzproduktion. Entlang des untersuchten Gradienten konnte eine ausgeprägte, kontinuierliche Verschiebung der Allokationsmuster festgestellt werden: Mit abnehmender Wasserverfügbarkeit nahm die Feinwurzelproduktion zu und das Verhältnis von oberirdischer:unterirdischer Biomasseproduktion ab. Anders als oberirdische Komponenten zeigte die Feinwurzelproduktion eine hohe Sensibilität gegenüber Unterschieden hinsichtlich hydrologischer Regime. In Übereinstimmung mit der Optimalitätstheorie der pflanzlichen Ressourcennutzung konnte dieses Allokationsverhalten in sowohl in Reaktion auf veränderte Niederschläge, als auch in Antwort auf auch veränderte Wasserspeicherkapazitäten beobachtet werden. Allokative Anpassungsmechanismen an Wassermangel wurden im Feinwurzelbereich zusätzlich durch morphologische Plastizität (Zunahme im Verhältnis von Oberfläche: Biomasse) und durch Regulierung der räumlichen Verteilung (zunehmende Konzentrierung von Feinwurzeln in der organischen Auflage) komplementiert. Im Gegensatz zu diesen komplexen unterirdischen Trockenheits-Antworten konnten keinerlei Anpassungen der Blattmorphologie an veränderte hydrologische Bedingungen festgestellt werden. Neben Reaktionen auf Wasserverfügbarkeit wurde die Fruchtbildung als zweiter wesentlicher Einfluss auf das Allokationsverhalten der Buche erkannt. Eine deutliche Ressourcen-Allokation zu Gunsten der Fruchtentwicklung beeinträchtigte maßgeblich das oberirdische vegetative Wachstum, insbesondere den Stammholzzuwachs. Auf Grund einer hohen Attraktionsstärke der Früchte gegenüber C und N führte zunehmende Fruktifizierung auch zu einer Gewichts- (und Größen-) Abnahme der Einzelblätter und somit zu reduzierter Bildung von Blattmasse und Bestandesblattfläche (LAI). Neben dieser Abnahme an assimilierender Blattoberfläche führte auch eine deutliche Senkung der Blatt-Stickstoffgehalte in Folge der reproduktiven Ressourcenwidmung mutmaßlich zu einer Verschlechterung der C-Bilanz, sowohl im Mast- als auch im Folgejahr. Eine Analyse klimatischer Einflussfaktoren auf das Mastverhalten legt nahe, dass die Blütenbildung der Buche durch Überschreitung eines Schwellenwertes der Kohlenstoffassimilation im Frühsommer (Juni-Juli) induziert wird. Sofern diese Schlüsse zutreffen, unterliegt das zeitliche Muster der Fruktifikations-Antwort auf Witterungsauslöser einer Rückkopplungskontrolle durch pflanzliche Stickstoff-Dynamik. Vor dem Hintergrund anhaltend erhöhter Stickstoffdepositionen ergäbe sich aus diesem Mechanismus eine zusätzliche Belastung für das zukünftige vegetative Wachstum der Buche. Es ist anzunehmen, dass die in dieser Studie belegte hohe allokative Plastizität in Altbäumen Fagus sylvatica dazu befähigt, ihre hohe Konkurrenzkraft in einem breiten Spektrum hydrologischer Regime zu entfalten. Darüber hinaus werden die hier dargestellten Mechanismen einer langfristigen Trockenheitsanpassung mutmaßlich zu einer gesteigerten Resistenz und Resilienz von Buchen-Altbeständen gegenüber Ereignissen extremer Sommertrockenheit beitragen.