Historical and Projected Changes in Chill Hours and Spring Freeze Risk in the Midwest United States

Implications of climate model selection for projections of decision-relevant metrics: A case study of chill hours in California

Moderate California winters often result in delayed, erratic or extended bloom, inadequate overlap with pollenizers, poor leafing-out, low fruit set, and irregular fruit maturity. In recent years, use of rest-breaking agents has become commonplace in California sweet cherry (Prunus avium L.) culture, mainly to promote earlier bloom and fruit maturity, but also to promote uniform flowering and overcome lack of marginal chilling. Variable responses by different cultivars and in different seasons may be due to different chilling requirements, despite little variation in genetic background for chill requirement in California's commercial cultivars. Other sources of variation include the activity of the rest-breaking agent used, concentration and carrier volume. A minimum amount of effective chill appears to be required for a given cultivar before rest-breaking agents can be effectively applied. This threshold, as exhibited by degree of response to treatment, can be an important indicator of when to spray. Method of measuring chill accumulation, and thus, timing of applications, varies by region and historic acceptance. California's tree fruit industry typically uses the 45 °F “chill hour” model. The Utah Chill Unit Model and the Modified 45 °F Chill Hours Model had not been thoroughly tested under California conditions nor with the rest-breaking chemicals that are in use today in California. We tested our research results against these models and the Dynamic Model developed in Israel and concluded that the Dynamic Model provided the best explanation of responses in our experimental trials. We have been developing recommendations for application of rest-breaking chemicals based on Dynamic Model chill portion accumulation.

In this study, four cider apple ( Malus ×domestica ) cultivars, Brown Snout, Dabinett, Kingston Black, and Yarlington Mill, were collected from four orchards, two in northwest Washington and two in central Washington, to compare juice quality characteristics. Northwest Washington has a cool, humid summer climate (16.0 °C on average during this study) and is the origin of the state’s cider apple industry, while central Washington has a hot, dry summer climate (22.1 °C on average during this study) and is the center of the state’s dessert apple industry. Each year from 2012 to 2015, fruit of the four cultivars were harvested and stored at each orchard until they were collected. Fruit were pressed and the juice analyzed for five quality characteristics important to cider making: soluble solids concentration [SSC (%)], specific gravity (SG), pH, titratable acidity [TA, malic acid equivalent (g·L −1 )], and tannin [tannic acid equivalent (%)]. Harvest dates and climate data were recorded annually for each orchard location. There were no significant differences in any of the juice quality characteristics due to region and no significant interaction of region, cultivar, and/or year. Results did show, as expected, a significant difference in all five juice characteristics due to cultivar. ‘Brown Snout’, ‘Dabinett’, and ‘Kingston Black’ were higher in SSC and SG than ‘Yarlington Mill’; ‘Dabinett’ had the highest pH and lowest TA while ‘Kingston Black’ had the lowest pH and highest TA; and tannin was highest in ‘Yarlington Mill’ and lowest in ‘Kingston Black’. There was also a difference in SG and tannin due to year; SG was lowest in 2013 while tannin was highest in 2012. The difference in SG from year to year may be a result of variable year-to-year storage time at each orchard before collection of fruit. The difference in tannin from year to year was likely due to climatic variation over the four years of this study. On average, growing degree days (GDD) increased 10% and chilling hours (CH) decreased 10% from 2012 to 2015 in both regions. Classification of the four cultivars included in this study differed from historical records at the Long Ashton Research Station (LARS) in England; in the current study, the four cultivars exhibited tannin levels below 0.20% and would not be classified as bitter, unlike their historical classification at LARS. Results from this study indicate that variations in juice quality characteristics occur between cultivars as expected and occur within a cultivar from year-to-year, but for the four cultivars included in this study variations did not occur due to production region in Washington.

For future climate projections to be useful they must be actionable at the local level. In this study, we develop daily temperature and precipitation climate scenarios suitable for use in projections of drought, energy use, water use, and crop production. We investigate the magnitude of future changes to air temperature and precipitation in the Midwest United States in response to three future climate change scenarios. Results are used to assess changes to incidence of precipitation extremes and human comfort (using heat index) associated with the anticipated climate changes in the region. We use self‐organizing maps and random forest based techniques to generate daily realizations of temperature and precipitation for 279 weather stations in a region centred on Illinois. We determine that the random forest model performs best for maximum and minimum temperatures, while the self‐organizing map performs best for precipitation. Using nine models from the Coupled Model Inter‐Comparison Project Phase 5, downscaled daily temperature and precipitation values are generated for low, moderate, and high greenhouse gas emissions scenarios for historical and future periods. Based on recent trends, we focus our results on the high emissions scenario, and show an average increase of 4.3°C in maximum daily air temperature across the region for the 2071–2100 period. Precipitation decreases by up to 15% in the southern half of the study region, with a similar percentage increase in the northern half of the region. The regional environmental changes result in an increase of 5.8° in average summer heat index, and increase of 48% in the number of days likely to produce extreme heat, and a decrease in the average value of the standardized precipitation and evapotranspiration index of 1.9 (indicating increased drought) across the region by 2100.

Climate and especially air temperature have a direct and high impact on nut trees in arid regions. In this regard, the use of multi-model ensemble projections as more reliable models is important. In this study, based on multi-model ensembles (MME) from the coordinated regional climate downscaling experiment Middle East North Africa (CORDEX-MENA), the air temperature in RCP8.5 and RCP4.5 pathways in pistachio cultivation areas in Iran was projected. The period 1980 to 2017 was identified as the reference period. Due to the sensitivity of climate change and the existing uncertainties, the hourly temperatures based on the models of chilling hours (CH) and chilling portions (CP) were also used for the reference period. The results of CORDEX simulations for pistachio cultivation areas suggest that the minimum and maximum annual air temperature (MMAT) and growing season temperature (GST) at the end of the current century compared to 1980–2017 as the reference period will increase significantly to 4 °C. The downward trend of winter chill accumulation during the cold season based on observational data will confirm the increase in air temperature in pistachio cultivation areas in Iran. In the output simulation of CORDEX project, the date of flowering pistachio tree for late-maturing varieties by 2080 under representative concentration pathway (RCPs) RCP8.5 and RCP4.5 will occur 16 days and 6 days sooner, respectively. The amount of heat accumulation or growing degree days (GDD) in the future in pistachio cultivation areas will be increased, and deviation from the historical period, based on RCP8.5 and RCP4.5 on average, will occur 3200 and 2600 GDD, respectively.

Agroclimatic requirements and phenological responses to climate change of local apple cultivars in northwestern Spain

While the Midwestern USA ranks among the world’s most important corn-soybean production regions, the area also produces a variety of high-value specialty crops. These crops are an important component of the region’s rural economy with an estimated value of $1.8 billion in 2012. More profitable per-acre than many row crops, specialty crops also have higher production-related risks. They are generally more sensitive to climatic stressors and require more comprehensive management compared to traditional row crops. Temperature and precipitation fluctuations across the Midwest directly impact specialty crop production quantity and quality and indirectly influence the timing of crucial farm operations and the economic impacts of pests, weeds, and diseases. Increasingly variable weather and climate change pose a serious threat to specialty crop production in the Midwest. In this article, we assess how climate variability and observed climatic trends are impacting Midwestern specialty crop production using USDA Risk Management Agency data. In addition, we review current trends in grower perceptions of risks associated with a changing climate and assess sustainable adaptation strategies. Our results indicate that weather-induced losses vary by state with excessive moisture resulting in the highest total number of claims across all Midwestern states followed by freeze and drought events. Overall, specialty crop growers are aware of the increased production risk under a changing climate and have identified the need for crop-specific weather, production, and financial risk management tools and increased crop insurance coverage.

U.S. agricultural and rural communities face ongoing challenges including profitability and environmental stresses that threaten the livelihoods and well-being of many who work the land and/or live in rural areas. Ongoing concerns exist regarding the sustainability of small family farms. Using sustainable agricultural practices and promoting locally produced specialty crops will provide new opportunities for small farms to be both profitable and environmentally sustainable. Specialty nut crops and Non-Timber Forest Products crops (e.g. eastern black walnut, elderberry, log-grown shiitake mushrooms, ginseng) produced in perennial polycultures (e.g. agroforestry systems, AFS) offer opportunities to introduce environmentally, economically and socially sustainable agricultural systems that create new opportunities for farmers, ranchers, forest landowners, and families in rural communities. An integrated, long-term approach involving cultivar selection and breeding, field production techniques, market and consumer studies, sound financial decision support tools and grower training is needed to bring specialty crops into the sustainable agriculture mainstream. This chapter summarizes recent research carried by the University of Missouri Center for Agroforestry (UMCA) on specialty crops, focusing on edible tree nuts (chestnuts and black walnuts), fruits and berries (elderberry), and other potential specialty crops.

To better understand dense fog events in the midwestern United States, a fog climatology was developed that examines the surface weather conditions at dense fog onset and during dense fog events, in relationship to fog duration. Surface airways hourly observations for the period 1948–96 were examined, focusing primarily on Peoria, Illinois, during the cold season (October–March). Temperature, winds, and visibility at dense fog onset did not prove to be useful in differentiating between short- (1–2 h) and long- (>5 h) duration dense fog events. However, it was found that once dense fog forms, it is more likely to persist if the horizontal visibility is 200 m (1/8 mi) or less and the ceiling height lowers to 30 m (100 ft) or less. Further, dense fog events at Peoria tend to last longer if they are widespread, that is, when many other midwestern surface airways hourly stations also report dense fog. When dense fog develops early in the night to the hours just after midnight, it is more likely to persist than when it develops later in the night or during the day. This was found to be the case for many other midwestern stations as well. Fog events forming earlier in the night may last longer because of the absence of solar insolation upon the fog layer during the night. As longer-duration fogs often become more opaque and more widespread than short-duration events, more time may be required to dissipate fog once the sun has risen. Dense fog onset time and the physical dimensions of the fog events appear to be the best predictors of fog duration considering all types of fog in the Midwest.

There has been an increase in tile drained area across the US Midwest and other regions worldwide due to agricultural expansion, intensification, and climate variability. Despite this growth, spatially explicit tile drainage maps remain scarce, which limits the accuracy of hydrologic modeling and implementation of nutrient reduction strategies. Here, we developed a machine-learning model to provide a Spatially Explicit Estimate of Tile Drainage (SEETileDrain) across the US Midwest in 2017 at a 30-m resolution. This model used 31 satellite-derived and environmental features after removing less important and highly correlated features. It was trained with 60,938 tile and non-tile ground truth points within the Google Earth Engine cloud-computing platform. We also used multiple feature importance metrics and Accumulated Local Effects to interpret the machine learning model. The results show that our model achieved good accuracy, with 96 % of points classified correctly and an F1 score of 0.90. When tile drainage area is aggregated to the county scale, it agreed well (r2 = 0.69) with the reported area from the Ag Census. We found that Land Surface Temperature (LST) along with climate- and soil-related features were the most important factors for classification. The top-ranked feature is the median summer nighttime LST, followed by median summer soil moisture percent. This study demonstrates the potential of applying satellite remote sensing to map spatially explicit agricultural tile drainage across large regions. The results should be useful for land use change monitoring and hydrologic and nutrient models, including those designed to achieve cost-effective agricultural water and nutrient management strategies. The algorithms developed here should also be applicable for other remote sensing mapping applications.

Neste estudo é apresentada a composição e similaridade florística de espécies vasculares sinantrópicas em uma área periurbana antropizada, no município de João Pessoa, Estado da Paraíba, e sua relação com outras floras sinantrópicas. Foram encontradas 98 espécies, em 75 gêneros e 30 famílias. Entre as espécies, 41,84% são cosmopolitas; 29,6%, pantropicais; 13,3% ocorrem apenas no cone sul da América; 8,2%, neotropicais; 5,1%, gondwânicas; e 2% ocorrem em toda a América. Asteraceae e Poaceae foram as famílias mais representativas em número de espécies. Os resultados foram comparados com os de outros levantamentos florísticos correlatos, utilizando o índice de similaridade de Sörensen, e observou-se que não é somente a proximidade geográfica entre os locais estudados que reflete uma maior similaridade florística entre as áreas, e sim a amplitude dos táxons e a presença de micro-habitat semelhante. A área de estudo está relacionada a uma área inserida na região Centro-Oeste do Brasil.

Mosquitoes are ecologically and economically important invertebrates that transmit numerous diseases and are an integral part of the food web in many terrestrial and aquatic ecosystems. Despite their importance, there have been no central repositories for occurrence or abundance records of mosquitoes in the United States. To enable research dependent on the geographic distribution and abundance of mosquito species, we built a database of occurrence records collected by many individuals and agencies, primarily in the United States and with emphasis on unpublished data in the Midwest region. This resource is invaluable to researchers studying mosquito ecology, disease vectors and pathways, and insect pests. The database contains 542 144 occurrence records, and each record includes information on sex, life stage, sampling method, presence/absence or abundance, and date and location of sampling. The accessibility of this resource will directly impact management and planning for mosquito‐borne diseases with region‐specific or species‐specific modeling. Because there is little centralized ecological information on mosquitoes, this database is foundational to expanding knowledge of mosquito ecology.

Complex mixtures of Pesticides in Midwest U.S. streams indicated by POCIS time-integrating samplers

System reliability worth assessment at a midwest utility—survey results for residential customers

This book is about the lives of Mexican working-class people in the neighborhood of South Chicago. The ethnic, Mexican migrant community sits at a crossroads, where the dividing lines of class, color hierarchies, gender, and belonging define their everyday lives. This book gathers stories about the working-class Mexicans who have come to make the city of Chicago their home. It is forcefully suggested in this book that the United States is a nation of immigrants and will continue to be so despite a resurgence of American nationalist rhetoric that seeks to reposition an idealized and racialized white, sovereign subject at its center. Ethnographically, the study focuses on documenting the lives of first- and second-generation Mexican migrants who came and settled from the states of Zacatecas, Guanajuato, Jalisco, and Michoacán to the US Midwest region, and Chicago in particular. Borders and borderlands are central themes in these stories during, and especially after, 2010, not as a transnational cultural moment but as a fundamentally transborder one. Indeed, the book argues that yarderos now find themselves at the crossings and inspections of multiple borders, sometimes not of their own making.