Eighty-three Didelphis virginiana from the Portland metropolitan area were collected and studied from December 1974 through May 1976. Males averaged 3394 g, females 2318 g. An annual sex ratio of 68.7:31.3 was recorded. Data indicate the possibility of a year-round breeding season and suggest the occurrence of three peaks of reproductive activity: January-February, April-May and October-November. The six primary foods consumed annually are: leaf litter, mammals, gastropods, earthworms, grasses and pet food. Seasonal composition and diversity in the diet is marked. Five new parasite-host records were established. These include mites: Androlaelaps fahrenholsi, Haemogamasus nidi, Eulaelape stabularis tick, Ixodes angustus, and a nematode, Toxocara canis. Both minimum and maximum temperature, and perhaps precipitation to a lesser degree, affect the activity of the species. Nest building by an immature opossum is described.

Thesis (Ph. D.)--University of Chicago, 1912. / "Reprinted from The Botanical Gazette, Vol. LII, No. 1."

Thesis (Ph. D.)--University of Chicago, 1912. / "Reprinted from The Botanical Gazette, Vol. LII, No. 1." Also available on the Internet. Also issued online.

1 ABSTRACT Charles University in Prague Faculty of pharmacy in Hradec Králové Department of pharmacognosy Student: Václav Předota Supervisor: PharmDr. Marie Kašparová, PhD. Title of diploma thesis: Plant tissue culture of Juniperus virginiana The derivation of callus cultures from leaves of Juniperus virginiana (varieties Hetzii, Glauca and Grey Owl) and determination of their growth curves were studied in this work. The cultures were cultivated at the temperature of 25 řC and light period of 16 hours light/8 hours dark on the Schenk and Hildebrandt medium with the addition of 3.0 mg.l-1 α-NAA and 0.2 mg. l-1 kinetin. It is clear from the growth curves, that all three varieties reached their maximum in growth on 35th day of the cultivation. The best results were achieved by variety Glauca.

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Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmacognosy Student: Lenka Srbová Supervisor: PharmDr. Marie Kašparová, Ph.D. Title of diploma thesis: Tissue culture of Juniperus virginiana L. as a promising source of podophyllotoxin. The diploma thesis deals with the cultivation of Juniperus virginiana tissue cultures. A growth was observed at Juniperus virginiana two years old culture (variety 'Glauca' and 'Grey Owl') after adding various concentrations of phenylalanine (1 mmol.l-1, 10 mmol.l-1 and 100 mmol.l-1 ) at selected time intervals. The results show that the highest increase in callus fresh weight was detected at Juniperus virginiana variety 'Grey Owl', particularly on the 14th day after adding 10 mmol.l-1 phenylalanine. Suspension culture was successfully derived from the Juniperus virginiana two years old callus culture (variety 'Glauca').

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Cheryl R. Boyer / Pine bark (PB) has been the principal component of nursery crop substrates in the United States for more than 60 years. Substrate material used for the purpose of growing ornamental plants in the Great Plains is generally shipped a great distance, primarily from the Southeastern U.S., due to a lack of pine plantations in this region. Eastern redcedar (Juniperus virginiana L.; ERC), an aggressively weedy tree species, has been identified as a possible alternative to PB for nursery substrates. The objective of this thesis was to evaluate the establishment of Miscanthus sinensis N.J. ‘Little Kitten’ (dwarf maiden grass), Rosa (L.) ‘Radtkopink’ (Knockout® rose), Ilex glabra (L.) A. Gray ‘Compacta’ (holly), Ulmus parvifolia Jacq. ‘Emer II’ (Allee® lacebark elm), Sedum telphium L. ‘Autumn Joy’ (sedum), Hosta Tratt. ‘Sum and Substance’ (hosta), and Hemerocallis L. ‘Charles Johnston’ (daylily) in three substrate mixes. These substrate mixes consisted of 80% PB: 20% sand, 80% ERC: 20% sand, and 40% PB: 40% ERC: 20% sand. At the end of the production phase differences in growth were observed in maiden grass, holly, lacebark elm, and sedum. At the end of the landscape establishment phase, no differences in growth were observed in any species except holly and hosta. To attempt to overcome the sub-optimal physical properties of ERC (high air space and low container capacity), cyclic irrigation was used to evaluate growth of Sedum spectabile Boreau ‘Autumn Fire’ (sedum), Rudbeckia fulgida Aiton ‘Goldstrum’ (black-eyed susan), and Hibiscus moscheutos L. ‘Luna White’ (hibiscus) in the same 3 substrates. The objective of this study was to evaluate the affect of irrigation frequency (1x, 2x, 3x, or 6x per day) and substrate ERC content on plant growth. Sedum had the greatest growth index (GI) shoot dry weight in PB and when irrigated 1x and 2x per day had the greatest root dry weight regardless of substrate. Irrigation frequency had no significant difference for GI and shoot dry weight Black-eyed susan had the greatest GI and shoot dry weight when grown in PB. Irrigation frequency only had an impact on shoot dry weight of black-eyed susan; plants irrigated 1x, 2x, and 3x per day had the greatest growth. Hibiscus had greatest growth in PB: ERC mix. Irrigation frequency had no impact on growth of hibiscus. Cyclic irrigation does not overcome low water holding capacities in these three species. Overall, ERC can be used as a partial replacement to PB (up to 50%). However, further research evaluating effects of different fertility regimes on ERC substrate is warranted.

1 ABSTRACT Charles University in Prague Faculty of pharmacy in Hradec Králové Department of pharmacognosy Student: Kateřina Šandová Supervisor: PharmDr. Marie Kašparová, PhD. Title of diploma thesis: Plant tissue cultures as a potential source of phenylpropanoids II. This diploma thesis deals with the monitoring of jasmonic acid biotic elicitation impact on the production of podophyllotoxin in Juniperus virginiana suspension culture. The monitoring was carried out in two varieties of J. virginiana: var. 'Glauca' (7th and 19th passage) and var. 'Hetzii' (7th passage). The elicitation of the suspension culture was performed in 4 jasmonic acid concentrations: 0.005 mmol/l, 0.05 mmol/l, 0.5 mmol/l, 5 mmol/l. Samples were taken after 6, 24, 48 and 168 hours of elicitation. The best podophyllotoxin production increase was observed in the suspension culture of Juniperus virginiana var. 'Glauca' (7th passage). To achieve this result, the concentration of elicitor was 5 mmol/l and elicitor was applied for 168 hours. The podophyllotoxin production percentage was 0.067% and production increased by 179% over the control. Keywords: Juniperus virginiana, suspension cultures, podophyllotoxin, elicitation

Isoprene is the most abundant volatile organic compound (VOC) emitted from vegetation, mainly trees. Because it plays an important role in tropospheric chemistry leading to formation of pollutants and enhancing the lifetime of the greenhouse gas methane, concern about the response of isoprene emissions to the rise in atmospheric CO2 concentration and global climate change has been increasing over the last few years. The consequences of predicted climate change will have complex repercussions on global isoprene emission. The increasing atmospheric CO2 per se will have direct effects on terrestrial vegetation since CO2 is the substrate of photosynthesis. Because photosynthesis is limited by CO2 at current ambient concentrations, an increase in CO2 is expected to increase leaf biomass (i.e. isoprene emitting surface). Predicted warmer climate, extended drought periods, the possible shift in plant species in favour of isoprene emitters and the increase in length of growing season, may cause an increase in global isoprene emissions with profound perturbations of air quality and the global carbon cycle. The aim of this thesis was to investigate the effect of environmental variables such as light, temperature, drought and leaf-to-air vapour pressure deficit (VPD), and the short- and long-term effect of atmospheric [CO2] on isoprene emission from temperate and tropical tree species. Both leaf and whole ecosystem level fluxes were studied. At the leaf scale, a short-term experiment with leaves of potted two-year old trees of Quercus virginiana was carried out, exposing plants to two drying-rewatering cycles. Leaf isoprene emission fell, but the process was considerably less sensitive to water stress than photosynthesis and stomatal conductance. In drought conditions, the large reduction in photosynthesis caused the percentage of fixed carbon lost as isoprene to increase as plants became more stressed, reaching peaks of 50% when photosynthesis was almost zero. Isoprene emissions also showed a strong negative linear relationship with pre-dawn leaf water potential (psi-leaf). In another experiment carried out at the large enclosed facility of Biosphere 2 (B2L, Arizona, USA), studying isoprene emission from leaves of three-year-old plants of Populus deltoides grown at three CO2 atmospheric concentrations (430, 800 and 1200 mu mol mol-1 CO2) in non-stressed conditions, instantaneous increases in atmospheric [CO2] always resulted in a reduction of isoprene emission and a stimulation of photosynthesis. Moreover, in the long-term, the CO2 inhibition effect for isoprene emission became a permanent feature for plants growing under elevated [CO2]. Again, isoprene emission was less responsive to drought than photosynthesis. Both water-stress and high VPD strongly stimulated isoprene emission and depressed photosynthetic rate as a result of stomatal closure and the resulting decreases in intercellular [CO2] (Ci). This also led to a dramatic increase in the proportion of assimilated carbon lost as isoprene. The effect of atmospheric elevated [CO2] and its interaction with high VPD and water stress on ecosystem gross isoprene production (GIP) and net ecosystem exchange of CO2 (NEE) in the Populus deltoides plantations was also studied. Although GIP and NEE showed a similar response to light and temperature, NEE was stimulated by elevated CO2 by 72% and depressed by high VPD, while GIP was inhibited by elevated CO2 by 58% and stimulated by high VPD. Similar to what was observed at leaf level, under water stress conditions GIP was stimulated in the short term and declined only when the stress was severe, whereas NEE started to decrease from the beginning of the experiment. This contrasting response led the percentage of assimilated carbon lost by the ecosystem as isoprene to increase as water stress progressed from 2.5% and 0.6% in well-watered conditions to 60% and 40% for the ambient and the elevated CO2 treatments, respectively. Again, we found water limitation and high VPD off-set the inhibitory effect of elevated CO2, leading to increased isoprene emissions. The effect of a mild water stress on GIP and gross primary production (GPP) was also observed in the model tropical rainforest mesocosm of B2L. Although GPP was reduced by 32% during drought, GIP was not affected and correlated very well with both light and temperature. The percentage of fixed C lost as isoprene tended to increase during drought because of the reduction in GPP. Consumption of isoprene by soil was observed in both systems. The isoprene sink capacity of litter-free soil of the agroforest stands showed no significant response to different CO2 treatments, while isoprene production was strongly depressed by elevated atmospheric [CO2]. In both mesocosms, drought suppressed the sink capacity, but the full sink capacity of dry soil was recovered within a few hours upon rewetting. In summary, elevated CO2 increased biomass production and photosynthesis while depressing isoprene production. However, both drought and VPD may off-set the CO2 effect and lead to enhanced isoprene emission. We conclude that the overall effect of global climate change could be of enhancing global isoprene emissions while depressing the soil sink, and that the soil uptake of atmospheric isoprene is likely to be modest but significant and needs to be taken into account for a comprehensive estimate of the global isoprene budget.

Anthropogenic change in the Great Plains of North America within the past two centuries has facilitated extensive woody encroachment by eastern redcedar (Juniperus virginiana, hereafter redcedar). Conversion of grassland to redcedar woodland occurs rapidly as a result of the interaction between changing disturbance and land use patterns. In addition, redcedar encroachment causes compositional shifts in grassland floral and faunal assemblages, and may alter abiotic factors such that grassland restoration efforts are limited. The objectives of this study were to: 1) track vegetation and faunal assemblages in grasslands along a gradient of redcedar encroachment, 2) assess the capacity for experimental tree removal to promote re-colonization of grasslands by associated flora and fauna, and 3) examine the influence of scale on spatial relationships between small-mammal abundance and redcedar cover. During the first phase of my study, I examined herbaceous vegetation, woody vegetation, and small-mammal assemblages at grassland sites along a redcedar encroachment gradient in north-central Oklahoma. I noted hump-shaped trends in the capture rate, species diversity, and species evenness of small mammals along the redcedar encroachment gradient. In addition, higher levels of encroachment were associated with compositional shifts from grassland- to woodland-associated small mammals. Characteristics of the small-mammal assemblage along the gradient corresponded to increases in redcedar cover and the frequency of episodic management events within the past two decades. Experimental redcedar removal during the second phase of my study generally increased vegetation and faunal diversity in 2 years following treatment, and treatment sites having the highest pre-treatment levels of redcedar cover exhibited the greatest responses to tree removal. The results of my study suggested that within the time frame I examined, redcedar encroachment had altered the biotic characteristics of this system, but did not facilitate abiotic shifts capable of constraining rapid grassland recovery. Tree removal also appeared to modulate the effects of consecutive drought and flood years on small-mammal diversity during post-treatment. During the third phase of my study, I examined the strength of association between differences in percent redcedar cover and spatial abundance patterns of 4 common small-mammal species. I examined small-mammal abundance at three relatively small spatial scales (38, 154, and 616 m2) to determine how redcedar-mammal associations were stronger with increases in spatial scale. In addition, I determined whether the influence of spatial scale on redcedar-mammal associations varied along a gradient of redcedar encroachment. The strength of redcedar-mammal associations increased with spatial scale, but was strongest at sites having the lowest levels of encroachment. These results corresponded to variation in the spatial distribution of redcedar cover and compositional differences in the small-mammal species assemblage along the encroachment gradient. Studies examining the effects of woody encroachment will extend our understanding of successional processes and ensure that appropriate management is implemented in the conservation of these imperiled grassland ecosystems.