Field and laboratory experiments were conducted to elucidate various factors influencing the temperature-dependent larval eclosion of winter moth, Operophtera brumata L, in New England. We found no difference in duration of the embryonic stage of eggs reared from larvae collected in Massachusetts (MA) and on Vancouver Island, British Columbia (BC), where winter temperatures are rarely below freezing. The number of growing degree days (GDD) required for larval eclosion declined with the number of days chilled in the laboratory and number of days below freezing in the field, confirming the findings of previous studies. Thus, eggs hatched with fewer GDD, when the spring came later than usual. Date of oviposition had no effect on date of hatch. Eggs laid by naturally occurring (feral) females hatched sooner with lower GDD than eggs from laboratory-reared females from MA and BC held on the same trees over the winter. South-facing eggs on the stems of trees hatched on average 1.6 days sooner than north-facing eggs. Growing degree days calculated from bi-hourly measures of temperature were 15% greater than GDD estimates based on the average of daily maximum and minimum temperatures, as used by many GDD estimates made for online sources. Over two years, the mean GDD in ⁰C for hatch of feral eggs based on bihourly temperature measurements, a 1 Jan start date and a 3.9⁰C developmental threshold was 176.53 ± 6.35SE

Research was conducted using the Soil-Plant-Atmosphere-Research (SPAR) units at Mississippi State University, Starkville, MS to investigate temperature effects on warm- and cool-season turfgrasses. Data collected include clipping yield, total root biomass, and relative chlorophyll index (RCI). Cultivars and species in the study included: ‘Latitude 36’, ‘Tifway’, ‘MSB-285’, and ‘TifEagle’ bermudagrass, ‘Meyer’ zoysiagrass, ‘Penn A1/A4’ and ‘Penncross’ creeping bentgrass, ‘Midnight’ Kentucky bluegrass, ‘Fiesta 4’ perennial ryegrass, and ‘Falcon V’ tall fescue. Grasses were grown in the SPAR units at varying day/night temperature regimes. Clipping yield was collected every three days, and regression was used to determine the temperature at which clipping yield equaled zero. Root biomass was collected at the conclusion of the trial, while RCI was taken once weekly. Base temperature for warm-season grasses ranged from 12.5 to 13.2°C. Determined optimum temperatures ranged from 31.8 to 36.1°C for warm-season turfgrasses and 18.8 to 20.6°C for cool-season turfgrasses.

An improved knowledge regarding what spatial scale temperature data is needed for ice-prediction would improve calculations how ice-coverage has been affected over time. Which by extension would give insight how ice might response to climate change. The purpose of this study was to find out if ice-growth in Sävar River could be explained by both local and regional temperature data, and what factors beyond temperature affect ice-growth. To accomplish this, I analyzed time-lapse photos from Sävar River during a three-month period. I found out that the use of regional temperature data to explain ice-growth on a local scale is limited due to the differences in accumulated degrees. The local temperature data measurement accumulated -2281 °C from ice began to grow until the whole channel was ice-covered and the regional temperature data accumulated -1901 °C under the same period. My findings support the assumption that frazil ice in large concentrations seem to increase ice-growth. Furthermore, no relation between ice-growth/decrease and precipitation or wet spots was found in this study.

Understanding how climate determines species’ geographic distributions is an important question in ecology with direct implications for predicting climate change-driven range shifts. For Lepidoptera, growing degree-days, a measure of growing season length, has been shown to be an important predictor of species’ distributions in some cases. Most studies use a standardized estimate of base development temperature in their calculations of growing degree-days instead of a species-specific threshold so past investigations of the influence of growing degree-days on Lepidoptera distributions may not have been optimal. Species distribution models (SDMs) are a commonly used approach in ecology that typically only implicitly capture the underlying processes that limit a species’ distribution. A species-specific estimate of growing degree-days should better characterize these processes than standard thermal thresholds and thus improve the accuracy of species distribution models. In this thesis, I use species distribution modelling to model the geographic distribution of 30 moth species native to North America. I ask whether a) growing degree-days are the best climatic predictor of these moth species distributions at broad scales; b) a lab-estimated biological threshold (i.e., BDT) can scale up and improve the predictive ability of SDMs; and c) the quality of experiments used to estimate species-specific BDT influences the predictive accuracy of SDMs. To do so, I compare the predictive accuracy of a correlative model based on a commonly-used thermal threshold to define growing degree-days to a hybrid model with degree-days defined based on a species-specific thermal threshold. I found that the predictive performance of the hybrid models was indistinguishable from the correlative models likely because growing degree-days was not the best climatic predictor of the geographic distributions of the majority of these moth species. I also found that there was no link between the quality of the lab experiments and the difference in performance of the hybrid and correlative models. My findings suggest that lab-estimated thermal thresholds may not always scale up to be predictive at a broad scale and that more work is needed to leverage the data from lab experiments into broad scale SDMs. Determining the ultimate factors that limit species’ distributions will be critical in accurately predicting species’ range shifts response to future climate change.

No description available.

The bluegrass billbug (Sphenophorus parvulus Gyllenhal) and hunting billbug (Sphenophorus venatus vestitus Chittenden) have become important pests of orchardgrass (Dactylis glomerata L.) grown in Virginia, causing 40 - 100% stand losses according to a 2005 survey of over 324 ha (800 ac) of orchardgrass. Their sheltered feeding habits combined with a lack of labeled insecticides for orchardgrass make billbug control extremely difficult for this crop. Over two seasons, orchardgrass fields were surveyed for paired feeding holes caused by feeding of the billbug spring adult. Simultaneously, barrier pitfall traps, a standard method for determining the presence of billbugs in orchardgrass, were used to trap billbug adults in the fields. A comparison of these methods using a Wilcoxon sign-ranked test found no significant differences in the time when paired feeding holes were first observed in fields and when billbug adults were first trapped, showing that the methods are equally satisfactory for determining the presence of billbugs in orchardgrass. In addition, temperature data from SkyBit E-Weather® service, which are currently used to alert growers and other interested parties of pertinent billbug activity in orchardgrass, was compared to data from a field-based weather data logger over the two seasons. A comparison of these data showed high coefficients of correlation, indicating a close relationship between these two degree-day collection methods. Therefore, the SkyBit system can continue to be used for the alert system. A field-border application of Metarhizium anisopliae (Metschnikoff) Sorokin strain F52 (Met-52), an entomopathogenic fungus, was evaluated against billbug adults as they enter orchardgrass fields in the spring. Randomized pairs of treated and untreated plots were placed along the edge of an orchardgrass field in studies over two seasons. Plots were monitored for billbug adults using barrier pitfall traps, and billbug adults were checked for Met-52 infection. The Met-52 proved unsatisfactory for controlling billbugs in this study. A field efficacy trial was used to evaluate several insecticides and Met-52 against billbug adults in orchardgrass over two seasons. A randomized complete block design, four insecticide treatments and an untreated control were used in each of two trials. Samples from each treatment plot were dissected and checked for billbug life stages and for injury to orchardgrass plants. In one trial, plants in the Sevin XLR Plus® treatment were found to have a significantly higher percentage of injury to the crowns than all other treatments except Mustang Max. No other significant differences were seen in this study. / Master of Science in Life Sciences

Juniper (Juniperus spp.) encroachment into sagebrush (Artemisia spp.) and bunchgrass communities has reduced understory plant cover and allowed juniper trees to dominate millions of hectares of semiarid rangelands. Trees are mechanically masticated or shredded to decrease wildfire potential and increase desirable understory plant cover. When trees are masticated after a major increase in tree population density and associated decrease in perennial understory cover, there is a risk that invasive annual grasses will dominate because they are highly responsive to the increased resource availability that commonly follows removal of the main resource user. To determine if tree mastication increases resource availability and subsequently favors invasive annual or perennial grasses, we compared soil temperature, water, and nutrient microenvironmental conditions and seedling establishment and growth. We used the major rangeland weed, cheatgrass (Bromus tectorum L.), to represent invasive annual grasses and Anatone bluebunch wheatgrass (Pseudoroegneria spicata (Pursh) A. Löve), a natural accession of native bluebunch wheatgrass, to represent the perennial grasses of the sagebrush-bunchgrass plant community. These comparisons were made between and within paired-adjacent masticated and untreated areas at three locations in Utah dominated by Utah juniper (Juniperus osteosperma (Torr.) Little). Juniper tree mastication generally increased resource availability with masticated areas having greater soil temperature, soil water availability, and soil N supply rates than untreated areas. Prior to juniper tree mastication litter mounds were not found to be resource islands probably because juniper trees themselves were using subcanopy soil water and nutrients. After juniper tree mastication and elimination of these predominant resource users, litter mounds served as resource islands with greater soil water availability and N supply rates than bare interspaces during the critical time for seedling establishment in spring. Plant growth followed in line with greater resource availability after tree mastication with masticated areas having more productive although fewer invasive-annual and perennial grass seedlings than untreated areas. These results suggest that increases in resource availability and warmer spring temperatures associated with mastication will not necessarily favor invasive annual over perennial grass seedling establishment. Resilience of the sagebrush-bunchgrass community to return to dominance after juniper control will likely be greatly influenced by how much of the sagebrush-bunchgrass community remains following tree control and the intensity of propagule pressure by invasive species. If only invasive annuals remain when the trees are treated then invasive annuals would be expected to dominate the post-treatment plant community especially with their ability to establish inside litter mounds unless they were also controlled and perennial grasses planted at the time of treatment.

Orientador: Victor José Mendes Cardoso / Banca: Fábio Socolowski / Banca: Gustavo Habermann / Resumo: A germinação de sementes representa uma etapa crítica para a sobrevivência da maioria das fanerógamas. Composição de gases, temperatura e água são os principais fatores ambientais limitantes do processo de germinação. Entre esses, a temperatura e a água exibem maior grau de flutuação, tanto em escala temporal como espacial, no ambiente terrestre, funcionando como importantes sinalizadores ambientais para a semente. Os objetivos deste trabalho foram fornecer a caracterização básica dos padrões germinativos de quatro cultivares (Carioca comum, Iapar 81, IPR Graúna e IPR Uirapuru) de Phaseolus vulgaris L. (Fabaceae); determinar as faixas ótimas de germinação para cada cultivar (experimentos em gradiente térmico com água destilada); realizar experimentos com interação dos fatores temperatura e potencial osmótico com soluções de polietilenoglicol 6000, visando à aplicação de modelos matemáticos baseados nos conceitos de graus-dia, psi-dia e na combinação destes dois conceitos (modelo psi-graus-dia), para se efetuar a comparação da resposta germinativa de tais cultivares. A cultivar IPR Graúna apresentou a faixa ótima com maior variação de distintas temperaturas (nove temperaturas), baseando-se na velocidade média de germinação; contrastando com a Iapar 81, que não apresentou uma faixa ótima, mas sim um único ponto ótimo (32,6ºC). Nenhuma das quatro cultivares apresentou germinação acima de 38,2ºC nem abaixo de 10,3ºC nos experimentos em gradiente térmico (água destilada). As temperaturas base obtidas pelo modelo de graus-dia variaram de 8,4 a 9,2ºC. Os ajustes (todos os R2s ≥ 0,70) ao modelo psi-graus-dia foram adequados para todas as cultivares, tanto na faixa supraótima quanto na infraótima. Assim sendo, ainda que mais estudos sejam necessários para melhorar a qualidade dos ajustes obtidos em relação... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Seed germination constitutes a crucial phase in relation to the life cycle of plant species. The composition of gases, temperature and water availability are the main environmental factors that may hinder several germination processes. Temperature and water availability, for example, are able to fluctuate considerably and may act as environmental "status' indicators to the seeds. The present work was aimed at furnishing a basic characterisation of the germination patterns of four Phaseolus vulgaris cultivars, viz. "Carioca comum', "Iapar 81", "IPR Graúna" and IPR Uirapuru; assessing the optimum range of germination for each cultivar; conducting experiments in which the effects of temperature and osmotic potential were simultaneously analysed in order to deploy mathematical models concerning the concept of degree-days (thermal time) with the aim of comparing the germination response of such cultivars. "IPR Graúna' exhibited a wider optimum range of temperature (nine distinct values) and "Iapar 81" presented only one temperature value as the optimum temperature (32.6ºC). The four cultivars did not germinate at temperatures higher than 38.2ºC and lower than 10.3ºC. The base temperatures derived from the application of the thermal time models varied from 8.4 to 9.2ºC. Regarding the hydrothermal-time model, the quality of the data fitting were deemed to be adequate (R2s ≥ 0.70) both in the suboptimum range and in the supra-optimum range. Other researches should be conducted in order to corroborate the present findings; nonetheless, the common bean cultivars were able to be compared and contrasted and exhibited, on the whole, a relatively homogenous... (Complete abstract click electronic access below) / Mestre

長久以來，電力消費與尖峰負載預測之方法不外乎使用迴歸模式及時間序列模式。其選用之自變數往往很多，如國民生產毛額(GNP)、價格、冷氣機台數、冷氣度(Cooling Degree Days)、冷氣時…等，因而使得整個預測模式相當複雜。吾人嘗試簡單以「溫度」單一變數來解釋電力消費與尖峰負載，作迴歸模式與時間序列模式並比較各模式的優劣，尋最適模式適配於『電力消費與溫度』、『尖峰負載與溫度』，並且以台灣地區為例，作實證分析研究，研究結果顯示溫度因素在電力消費上確實佔重要地位。文中溫度因素之單位，選用最具代表性之冷氣度(CDD)來表示，方便吾人探討。

This Thesis presents a framework for modelling species-specific site quality index (SQI) at a spatial resolution of 250 m by integrating biophysical variables of growing degree days (GDD), soil water content (SWC), and incident photosynthetically active radiation (PAR) in descriptions of potential tree growth. Development of GDD maps is based on processing and blending remotely-sensed data acquired with the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on the Terra satellite and ETM+ sensor on Landsat-7 satellite at spatial resolutions of 250 m and 28.5 m. Descriptions of SWC are based on a temperature-vegetation wetness index (TVWI) that relies on MODIS-based optical and thermal image products. PAR is estimated with an existing solar-radiation distribution model. SQI is defined as a function of species vital attributes and species environmental response to GDD, TVWI, and PAR. The methods are applied to a balsam fir [bF; Abies balsamea (L.) Mill.] dominated region in northwest New Brunswick. Comparisons between SQI and field-based estimates of site index and enhanced vegetation index showed that about 66 and 88% of the values corresponding to a series of Forest Development Survey lines (691 in total) were within 16% of SQI values. On average 92.1% of high bF-content stands (> 50% composition) in the area fell on medium-to-very high SQI values (> 0.50). Based on these agreements, SQI can be perceived as a good predictor of potential tree-species growth in the selection of optimal sites for biomass and wood fibre production.