In the present century, ecosystems across the globe will be subject to profound changes in climate. Forests are expected to be particularly sensitive to such change as the long life span of trees limits the potential for rapid adaptation. In order to preserve commercial viability and the essential ecosystem services provided by forests, there has been much interest in strategies for managing the adaptation of trees to their climatic environment. Climate Matching has emerged as one such strategy, whereby climate models are used to identify provenances – tree populations at a particular locality - with seed expected to be well adapted to the future conditions of a particular planting site. Debate continues about the feasibility and merit of this and other approaches, but it has yet to be demonstrated that the underlying assumptions of Climate Matching are valid for focal European tree species. Furthermore, a potentially major omission thus far has been consideration of how the Climate Matching strategy might influence associated organisms. Given the widely demonstrated bottom-up effects of foundation species genotype that have emerged from the field of community genetics, it is possible that planting seed of non-local provenance could effect forest organisms such as insect herbivores. In this thesis, I investigate the underlying assumptions of Climate Matching and its community level consequences using a model system of cynipid oak galls on Quercus petraea. Following a general introduction to Climate Matching and the study system, in Chapter 2 I use data from a provenance trial of Q. petraea in France to explore a central assumption of the Climate Matching strategy: that provenances of focal tree species show climate associated variation in adaptive phenotypic traits. In Chapter 3, I explore correlations between these phenotypic traits and the abundance, diversity, and community composition of an associated guild of specialist gall-inducing herbivores. Tree phenological traits in particular showed strong patterns of adaptation to climatic gradients, and influenced the abundance and community structure of galling species. However, as the response to non-local tree provenances was not strongly negative, it was considered unlikely that mixed planting of local and Climate Matched provenances would have sever impact on the gallwasp community. Having assessed the bottom-up effects of provenance phenotypic variation on the galling community, my ultimate aim is to extend analysis to include associated hymenopteran inquilines and parasitoids. However, interpretation of effects at this level is hindered by taxonomic uncertainty, with a growing appreciation that morpho-taxa may not represent independently evolving lineages (i.e. ‘true’ species). In Chapters 4 & 5 I therefore develop approaches for addressing taxonomic uncertainty with this ultimate aim in mind. In Chapter 4, I apply a DNA barcoding approach to parasitoid and inquiline specimens reared from the provenance trial, and compare taxa based on barcodes with those based on morphology to identify points of taxonomic uncertainty. I also investigate the extent to which networks based on morphological and molecular taxa support contrasting conclusions of network properties. In Chapter 5 I explore the potential for molecular based resolution of species level taxonomic error in a challenging group of parasitoids: the genus Cecidostiba. Beginning with a framework of single locus DNA barcoding, I use data from multiple nuclear loci to reveal the existence of cryptic species. Finally, in Chapter 6 I explore the practicalities of Climate Matching in light of my empirical results, and suggest fruitful avenues for further research.

Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

Physical characteristics of a site that plant species inhabit may be useful in deriving the range of the species. Current range maps for tree species of the United States were originally developed by Elbert Little. These range maps were based primarily on observations. The purpose of this study was to update Little’s (Little, 1971) range maps of select southern oak species in Mississippi by calculating the topological, soil, and climatic features of sites using a Geographic Information System (GIS) to analyze environmental variables associated with species distributions. Data collected from databases were input into ArcMap and site data extracted using Hawth’s Analyst Tools. Stepwise logistic regression performed with site variables yielded the parameters used in predictive models to generate probability maps for each species across Mississippi. These probability maps demonstrate the potential to efficiently manage forests by giving a more encompassing view of species occurrence.

Many bottomland hardwood stands in southern Mississippi lacked management prior to Hurricane Katrina. Following removal of overstory oaks, no seed source was available to naturally regenerate these stands. Artificial regeneration became the most viable option, but information was lacking on how to successfully reestablish thousands of acres of bottomland forests quickly and successfully. Bareroot and conventional containerized seedlings of Nuttall oak (Quercus texana) and swamp chestnut oak (Quercus michauxii) were planted on two sites in southern Mississippi. After two growing season’s Nuttall oak exhibited similar survival to (93.4%), better groundline diameter growth (13.0 mm) than, and better height growth (68.8 cm) than swamp chestnut oak (92.5%, 6.6 mm, 43.9 cm, respectively). Bareroot seedlings had the highest survival (94.5%), best groundline diameter growth (10.3 mm), and best height growth (66.6 cm), though conventional containerized seedling survival (91.4%), groundline diameter growth (9.3 mm), and height growth (46.0 cm) were all acceptable. Considering seedling cost and overall performance, bareroot seedlings provide the most effective option for artificial regeneration on high quality bottomland hardwood sites.

Rising atmospheric CO2 and the need to understand potential impacts on terrestrial ecosystems has become increasingly recognized. Models can play a beneficial part in this research to enhance understanding of ecosystem responses to changing conditions like elevated CO2. In this study, data from a long term elevated CO2 experiment in a native forested ecosystem in east central Florida were employed to assess the utility of a multi-layer canopy photosynthesis model as a tool to better understand the responses to elevated CO2 in this ecosystem. Model results compared satisfactorily with the canopy gas exchange measurements in this ecosystem for the period modeled. Sensitivity analyses were used to evaluate the robustness of the model and understand the effects that changing model parameters had on model results, i.e. carbon assimilation in the system. The parameters evaluated included canopy height, leaf area density profile, number of canopy layers, maximum rate of carboxylation (Vcmax), and canopy species composition. Results of the sensitivity analyses point to structure and species as being important to carbon assimilation in this ecosystem. Although only an initial examination, this model could be a valuable tool to further understanding of the response of this important ecosystem to increasing CO2 and indicates that further work is certainly warranted.

A vegetation monitoring program was initiated at Big Oaks National Wildlife Refuge (Big Oaks NWR) to help understand the effects of fire management on critical wildlife habitat. The objectives of this study were to produce a baseline description of plant community structure and composition and to describe the landscape-level impacts of fire management within the refuge. These grassland communities are important for managing rare grassland wildlife species, especially Henslow's sparrows. Permanent plots were established in three managed grassland communities. Information on plant community species composition and structure was collected during 2000-2001. Andropogon viginiana and Solidago juncea were the dominant plant species in the permanent plots. Rhus copallinum and Liquidamber styraciflua were the dominant woody species. Changes in landscape structure were determined using aerial photographs and a geographic information system (GIS). Vegetation data layers were created for 1995 and 1998 with vegetation patches classified using the National Vegetation Classification System (NVCS). Field data was collected during 2000 and 2001 to validate the data layers. Changes in composition and structure of nine vegetation classes were compared between burned and unburned areas. Percent cover of grassland area increased while sparse woodland and shrubland decreased during the study period. The amount of total patches and total edge declined in the burn areas. Mean grassland patch size increased while the number of grassland patches and grassland edge decreased in the burn areas. Therefore, the grassland areas within the burn units were more homogeneous in 1998. The results of this study were related to Henslow's sparrow population estimates in the fire management units.

Nous avons étudié les réponses à la contrainte hydrique du système biologique formé par l'association plante hôte – communautés de champignons ectomycorhiziens (ECM) en prenant comme espèces modèles deux chênes méditerranéens correspondant à des types biologiques contrastées décidu (Quercus pubescens) et sempervirent (Q. ilex). Nous avonstesté l'hypothèse selon laquelle les interactions fonctionnelles entre plantes hôtes et communautés associées pourraient être régulées par le niveau de ressource hydrique. A l'aide d'une expérimentation réalisée en conditions contrôlées, nos résultats ont montré que Q. pubescens réduisait davantage sa production que Q. ilex en réponse au déficit hydrique. La colonisation racinaire par les champignons ECM a varié selon les deux chênes et la disponibilité de l'eau. La longueur des racines colonisées était positivement corrélée à la croissance des plantes et à l'immobilisation des nutriments chez l'espèce décidue Q.pubescens mais pas chez Q. ilex. In natura, nous avons testé les traits de communautés ectomycorhiziennes dans un gradient environnemental de trois forêts de Q. ilex. Sur chaque site, le taux de colonisation racinaire et la richesse des espèces ECM ont diminué avec l'horizon échantillonné alors que parallèlement les ECM de la famille dominante Russulaceae augmentaient. Sur tous les sites, le type d'exploration dit «contact» était dominant, particulièrement dans le site sec. La composition des espèces a varié considérablement d'un site à l'autre avec un nombre élevé d'espèces rares, à l'échelle locale et à l'échelle régionale. Dans les trois sites, l'application d'une perturbation de sol de faible dimension a induit uneréponse forte de la communauté ECM. La diversité spécifique et la richesse ont diminué après la perturbation avec la disparition de la plupart des espèces de Russulaceae, de Cantharellaceae et de Clavulinaceae. Les types d'exploration contact ont fortement diminué alors que les types courte distance ont répondu positivement à la perturbation. Une mosaïque d'espèces stress-tolérantes comprenant plusieurs espèces des genres Sebacina sp et Helvellasp, ont dominé les communautés après la perturbation. Ces travaux apportent des éléments de compréhension du fonctionnement et de la réponse du système chênes méditerranéens - communautés ECM face à la contrainte climatique, les expérimentations in natura permettant d'affiner notre connaissance des stratégies écologiques de recolonisation ectomycorhizienneaprès perturbation. / The effect of drought had been investigated on the biological system -host plantectomycorrhizal community ECM- using different approaches. In a first part, we evaluated the drought-resistance of Quercus species and their associated ECM fungi, comparing the responses of two oak species differing in their leaf habitat, Q. pubescens vs Q. ilex (deciduous vs evergreen) in a controlled experiment. Our results showed that Q. pubescens reduced more its production than Q. ilex according to drought treatments. The total length of colonized fine roots was positively correlated with plant growth and nutrient immobilization in Q. pubescens but not in Q. ilex. In a second part, we investigated ECM community traits in three Q. ilex forests across an environmental gradient. At each site, both ectomycorrhizal colonization rate and species richness decreased with increasing soil depth, while the dominant family Russulaceae increased in abundance with increasing soil depth. At all sites, contact exploration type strongly dominated, with the highest abundance in the driest site. Species composition varied significantly across sites with high number of rare species at local and regional scales. At all sites, the application of an experimental soil disturbance provoked strong responses of the ECM community. Species richness and diversity decreased after disturbance with disappearance of numerous species of Russulaceae, Cantharellaceae and Clavulinaceae. The relative abundance of contact exploration types decreased after the disturbance whereas the opposite pattern was observed for short distance exploration type. A mosaic of stress-tolerance species of Sebacina sp and Helvella sp, dominated after disturbance. These studies provide an understanding of the functioning and the responses of the system Mediterranean oaks – ECM communities facing climatic constraints. In natura experiments provide us insights on our understanding of ecological strategies of ectomycorrhizal fungi after disturbance.

Thesis (D.Min.)--Southwestern Baptist Theological Seminary, 2006. / Includes bibliographical references (leaves 133-138).

The Garry oak (Quercus garryana) is a species of oak tree native to North America’s Pacific coast. Its range in Canada is limited to the east coast of Vancouver Island, the southern Gulf Islands, and two isolated groves in the Fraser River valley. It is most widespread and conspicuous in Greater Victoria, the urban area centred around the city of Victoria, British Columbia. Garry oaks themselves and areas of relatively undisturbed land containing Garry oaks are threatened in Victoria by a number of factors including land development, the tree’s unpopularity as an ornamental species, and fire suppression. The Garry oak’s predicament provides rationale for the central goal of this thesis, which is to explore how people have known these trees in the 165 years since Fort Victoria was established. Using a range of print sources, I identify five prominent areas of knowledge about the tree, or Garry oak cultures. These are: Garry oaks as significant of Britishness, Garry oaks as known through science, Garry oaks as significant individual trees, Garry oaks as remnants of pre-colonial landscapes, and Garry oaks as advocated for by conservationists. From these, I draw three key themes. First, many people have found Victoria’s Garry oaks valuable or important and expressed that sense of value in a variety of ways. Second, people have used Garry oaks in narratives of national identity, though in divergent ways: for some Garry oaks have been symbolic of Britain and Victoria’s supposed connection with the mother country, and for others Garry oaks are to be regarded only as a native species. Third, scientific language and concepts have been used to understand Garry oaks with increasing popularity over the past few decades, especially as public awareness grows of the oaks’ ecological crisis. Following recent work in cultural geography, I contend that people negotiate connections to place through trees such as Garry oaks. Though these findings must be understood to be preliminary, they can help to explain the plight of the Garry oak by casting light on ambiguities and dissonances in the ways that Victoria’s diverse citizenry relates to the places they inhabit. / Thesis (Master, Geography) -- Queen's University, 2008-10-08 13:47:50.049

Thesis (M.A.)--University of North Texas, Dec., 2007. / Title from title page display. Includes bibliographical references.