Recent and anticipated global change has focused concern on the role of forests in ecosystem functioning and carbon sequestration. Of key importance is identifying relevant factors that drive carbon and nutrient dynamics and the consequences of changes in these processes. Systems undergoing invasion by invasive woody species are particularly prone to changes. This study examined the branch and crown biomass and decay dynamics for the invasive Chinese tallow tree in Mississippi, USA as well as the influences of stand and site conditions on biomass modeling and arthropod contributions to fine woody debris decay. Coupling biomass and decay models presents a method for modeling carbon sequestration and nutrient turnover rates at the stand level. These predictions will aid our understanding of the consequences of ecosystem change, especially those driven by invasive species.

Chinese privet (Ligustrum sinense) is an invasive plant species in the United States (U.S.). This study utilized the most effective control measures found in the literature, and used financial analysis to identify the most cost effective management regimes to eradicate this species under different conditions. Management regimes were assessed using simulated scenarios created using six components, based on real parameters from the southern U.S.: infestation level, field coverage, stand density, herbicide application method, herbicide, and mechanical removal of privet. Financial impact on land expectation values (LEV) was analyzed and discussed for each simulated area conditions. Results suggest that the most cost effective management regime controlling privet varies according to these components. Privet control is economically feasible, and a positive LEV can be achieved for every area conditions. Finally, this study can serve as a guide to develop policies and incentives for invasive species control programs.

Recreational firewood collected from campers in Mississippi State Parks was investigated for factors associated with insect presence and their diversity. Insects were found in 20% of firewood and evidence of past feeding was found in 64.8%. Representatives of 35 families of insects were reared from collected firewood. These included representatives of Buprestidae, Cerambycidae, Curculionidae, Formicidae, and Rhinotermitidae. The effects of firewood age, moisture content, and source were also examined as effects on insect presence in firewood. At the same time, a survey of campers’ beliefs and attitudes about non-native woodborers was conducted. Exposure to public awareness campaigns had the strongest association on reported sources of firewood and support for regulations on firewood movement. However, no association was found between attitudes and beliefs and camper firewood habits. No association was found between camper responses to survey questions and biological factors from firewood collected from them.

In 1888, the lake Hjälmaren underwent a process of lowering by almost 2 metres with the aim of gaining 19.000 ha of arable land. This process had a wide array of ecological implications, and in connection with other historical events, it also resulted in spatial and social cracks dividing the city of Örebro laying on Hjälmaren’s west shore. The changing physical aspects of the city have led us to question the relationship of humans and species to the lake, but also to the stream Svartån connecting the lake and the city. Örebro used to be a city of collective practices and shared resources. It had much stronger ties to water as it used to be more present and made the city more centre-oriented. This does not apply today - the city’s development is oriented outwards, its centre lacks in quality non-consumerist spaces and capitalism and individualism are at the forefront. With this explorative design thesis, we propose solutions to activate Hjälmaren and Svartån. Our project widens the offer of common spaces and resources in Örebro, giving its residents more opportunities to interact in the everyday presence of water – just like in the past, but with a more modern spin.

No description available.

Natural dispersal mechanisms and biogeographical barriers have shaped species' native distributional ranges over millions of years. However, over the last few centuries, humans have dispersed species beyond their natural ranges. Those species that undergo explosive population growth and rapid expansion in the introduced region are considered as invasive because they have the potential to cause negative effects on desirable species and/or ecosystem services. In chapter II, I identified what ecosystem characteristics are more closely associated with successful establishment of exotic and native species, to have a better idea of where to concentrate our efforts and resources to prevent invasion events while preserving native species. I found that native and exotic species were differently affected by ecosystem properties. Exotic species were favored by human activities and low native species abundance and diversity. However, in Chapter III, I found that species functional traits, such as growth form and phenology, are more important to explain their response to ecosystem characteristics than native status under certain circumstances. The abundance and reproductive capacity of the evaluated plants were reduced when disturbances occurred during their respective active growing periods. This finding suggests that we need to have into account species-specific responses to ecosystem characteristics when managing biological invasions. Chapter IV examined phenotypic differentiation of native, expansive, and introduced populations of Baccharis halimifolia L. occurring in different regions of the world. The results suggest that there are significant phenotypic differences in germination and early growth among native, expansive, and introduced populations, which could have contributed to the success of B. halimifolia in the introduced and expansive ranges. Finally, in Chapter V, I used the information that I learned in the past projects to predict the spread of 45 exotic plants across southeastern United States and evaluated what landscape factors make an area more susceptible to be invaded. I found that the influence of landscape composition and configuration on invasion risk is species-specific. This result suggests that not only we have to consider species functional traits when managing biological invasions, as we saw earlier in the experiment with disturbance timing, but also species habitat preferences.

Armored scale insects (Hemiptera: Diaspididae) are among the most invasive insects in the world. They have unusual genetic systems, including diverse types of paternal genome elimination (PGE) and parthenogenesis. Intimate relationships with their host plants and bacterial endosymbionts make them potentially important subjects for the study of co- evolution. Also, in some groups, the adult female never sheds the second instars cuticle, and remains within its confines, a habit referred to as the pupillarial habit. Here we expand upon recent phylogenetic work (Morse and Normark 2006) by analyzing a partitioned dataset including armored scale and endoysmbiont DNA from one hundred and twenty three species of armored scales, represented by two hundred and fifty-four samples. Included were fragments of the nuclear protein-coding gene Elongation Factor 1α (EF1α), the D2 and D3 expansion segments of the large subunit ribosomal RNA gene 28S, and a region of mitochondrial DNA encompassing the 3' portion of cytochrome oxidase I (COI), and the 5' portion of cytochrome oxidase II (COII). Ribosomal 16S from the primary bacterial endosymbiont Uzinura diaspidicola was amplified as well. Two versions of our dataset were analyzed due to concerns over the possible effects of missing data. The first version (the full dataset) contained all 254 taxa, with every taxon having at least both the 28S and EF1α fragments. The second version (the core dataset) had only the 113 taxa for which all four fragments were available. Maximum parsimony, maximum likelihood, and Bayesian analyses were run on both versions of the dataset, as well as individually for each fragment. We find that our results were consistent across methods, and between the two versions of the dataset. It appears that including missing data had little effect on topology. Our results mirror that of the classic taxonomy, however we reconstruct a general lack of monophyly at the subfamily, tribal, and subtribal levels. Within the two major subfamilies, we reconstruct that the same developmental pathway has evolved independently. We reconstruct independent replacements of the pupillarial habit with the scale cover, followed by independent origins of early PGE. In each case there appears to be increased diversity in clades associated with the scale cover and early PGE. In light of this apparent increase we propose a new adaptive scenario under which early PGE may have evolved – the removal of male-killing paternal chromosomes. We also reconstruct the ancestor to the armored scales to Australasian in origins, and to have an ancestral diet breath that includes members of the Rosids and/or Monocot plant groups.

Early-successional habitats have become rare in much of the eastern United States, largely due to landuse change, forest maturation and the disruption of natural disturbance regimes. In addition to providing nesting habitat for shrubland species of high conservation concern, wildlife openings may be an important habitat for mature-forest birds during the postfledging period – a critical phase in the avian lifecycle with the potential for high mortality. The habitat requirements of birds during this time period are poorly understood. In this study I examined the relationship between habitat and landscape characteristics on; 1) the abundance of forest nesting birds in shrubland habitat during the postfledging season, and 2) the reproductive success of shrubland bird species. And lastly, I also examined the relationship between avian body condition and seed dispersal, with a focus on comparing native and invasive species. I found that the abundance of forest birds was strongly influenced by landscape characteristics, as well as food abundance and structurally complex vegetation. Shrubland birds varied in their response to habitat variables, but overall productivity was positively related to taller vegetation structure, and was negatively related to lower-dense vegetation. Frugivore diets were generalized, yet they selected native fruit more often than invasive fruit, and invasive fruit negatively affected condition. My findings are consistent with the results of previous studies of habitat use among postfledging birds, and suggest that, like for forest birds, habitat requirements for shrubland birds during the postfledging period differ from those during the nesting season. Hopefully these results will encourage other studies of this important, but poorly understood stage of the avian lifecycle.

Throughout the eastern United States, the spread of the hemlock woolly adelgid, Adelges tsugae Annand, has caused high mortality of eastern hemlocks Tsuga canadensis (L.). We recorded overwintering survival and fecundity of A. tsugae, and tree new growth at sites in the northeastern and southeastern United States and in a common garden experiment in Massachusetts. Overwintering mortality of A. tsugae was much higher in the north (87%) than the south (37%) in 2009, and showed significantly positive density-dependence in the north only. In 2010, overwintering mortality decreased in both regions but remained higher in the north (54%) than the south (34%), and, unlike 2009, density-dependent mortality was strongly negative in the north, and positive in the south. In both years, sistens fecundity was significantly higher in the south than the north, but we observed no density-dependent trends, and fecundity measurements were similar in the two years. The regional discrepancies in fecundity suggested the possibility of an evolutionary trade-off between overwintering mortality and sistens fecundity. However, when we reared samples in a common garden, we found that source region had no effect on either sistens fecundity or overwintering mortality, which suggests observed regional differences can be attributed to environmental factors rather than genetic differences. In our regional studies, branch samples from the north had significantly more new growth than those from the south in both 2009 and 2010, even though A. tsugae densities were comparable. This difference persisted in the common garden wherein branches inoculated with northern-derived A. tsugae had significantly higher new growth than those infested with southern-derived A. tsugae. These findings raise the possibility that A. tsugae may be evolving towards reduced virulence. If true, these findings may help explain why A. tsugae is killing hemlocks much more slowly now in New England than it did when it first invaded this region more than 20 years ago, or as it is doing now in more recently invaded regions in the southern United States.

Drift is a point of contention with pesticide applications, causing the need to research application methods that provide consistent efficacy while minimizing off-target movement. Experiments were conducted to evaluate eight undiluted herbicides on invasive woody plants, Chinese tallow (Triadica sebifera) and Callery pear (Pyrus calleryana), when applied individual plant treatment (IPT) via hack-and-squirt. Applications of undiluted aminocyclopyrachlor or imazapyr at 1 ml per 7.6 cm of tree diameter at breast height (DBH) made in the spring provided superior control over other herbicides or application timings. CamelBak® hydration reservoirs were evaluated for storage durability with eight undiluted herbicides. A third study was conducted to assess droplet size and distribution of Roadside Inc.’s new sprayer head for driftable fines. All nozzles were evaluated in a wind tunnel and produced droplet sizes above the benchmark for driftable fines (≤150 μm). The spray head also distributed droplets effectively from 2-30 feet from spray origin.