Changes in Snow Phenology from 1979 to 2016 over the Tianshan Mountains, Central Asia

Snowmelt from the Tianshan Mountains (TS) is a major contributor to the water resources of the Central Asian region. Thus, changes in snow phenology over the TS have significant implications for regional water supplies and ecosystem services. However, the characteristics of changes in snow phenology and their influences on the climate are poorly understood throughout the entire TS due to the lack of in situ observations, limitations of optical remote sensing due to clouds, and decentralized political landscapes. Using passive microwave remote sensing snow data from 1979 to 2016 across the TS, this study investigates the spatiotemporal variations of snow phenology and their attributes and implications. The results show that the mean snow onset day (Do), snow end day (De), snow cover duration days (Dd), and maximum snow depth (SDmax) from 1979 to 2016 were the 78.2nd day of hydrological year (DOY), 222.4th DOY, 146.2 days, and 16.1 cm over the TS, respectively. Dd exhibited a spatial distribution of days with a temperature of \u3c0 \u3e°C derived from meteorological station observations. Anomalies of snow phenology displayed the regional diversities over the TS, with shortened Dd in high-altitude regions and the Fergana Valley but increased Dd in the Ili Valley and upper reaches of the Chu and Aksu Rivers. Increased SDmax was exhibited in the central part of the TS, and decreased SDmax was observed in the western and eastern parts of the TS. Changes in Dd were dominated by earlier De, which was caused by increased melt-season temperatures (Tm). Earlier De with increased accumulation of seasonal precipitation (Pa) influenced the hydrological processes in the snowmelt recharge basin, increasing runoff and earlier peak runoff in the spring, which intensified the regional water crisi

Causes of Seeding Failure within the Tooele Fire Rehabilitation Project in Northwestern Utah

The original purpose of this study was to examine the influences of ecological site, seeding method and planting season on rangeland seeding success within the Tooele Fire Rehabilitation Project (TFRP) in northwestern Utah. The major objective of the TFRP, designed by the USDI Bureau of Land Management, was to establish a permanent cover of \u27Nordan\u27 crested wheatgrass (Aqropyron desertorum (Fischer ex Link) Schultes), \u27Luna\u27 pubescent wheat grass (Thinopyrum intermedium ssp. barbulatum (Schur) Barkw. and D. R. Dewey) and \u27Al kar\u27 tall wheatqrass (Thinopyrum ponticum (Podp.) Barkw. and D. R. Dewey) on approximately 20,000 ha of rangeland burned by a wildfire in July 1983. Thirteen combinations of site, method and planting season were identified within the study area; each was treated as an experimental unit. There were no significant differences (Pi0.05) in seedling densities between these treatment combinations. Means ranged from O to 1.9 seedlings/m2. There was significant variation (Pi0.05) among seedling densities within each treatment combination. Because of low seedling densities and non-uniform seedling establishment patterns, seedings within the study area were failures. Study effort was redirected to identify the causes of seeding failure. viii Among planting seasons and seeding methods, spring plantings and broadcast seeding contributed to failure. Most sites within the study area were suitable for seeding, with the exception of desert shallow loam. This site should not have been seeded because of steep topography and shallow soil. Planting during spring, broadcast seeding and the seeding of low potential sites explained only localized failure, however. The absence of crested wheatgrass seedlings within the study area was a major factor contributing to failure. Only two crested wheatgrass plants were found on a total of 195 permanently established transects. Of the three species seeded, crested wheatgrass was the best adapted to site conditions. Seeding technique was considered the most important factor causing failure. Contract workers on the project had no rangeland seeding experience. Drills were not properly equipped to control seed placement at the proper soil depth. Seeding was done during periods when site conditions were unfavorable. There was no evidence suggesting weather, grasshopper damage or cheatgrass competition caused failure

Seasonal temperature acclimatization in a semi-fossorial mammal and the role of burrows as thermal refuges.

Small mammals in habitats with strong seasonal variation in the thermal environment often exhibit physiological and behavioral adaptations for coping with thermal extremes and reducing thermoregulatory costs. Burrows are especially important for providing thermal refuge when above-ground temperatures require high regulatory costs (e.g., water or energy) or exceed the physiological tolerances of an organism. Our objective was to explore the role of burrows as thermal refuges for a small endotherm, the pygmy rabbit (Brachylagus idahoensis), during the summer and winter by quantifying energetic costs associated with resting above and below ground. We used indirect calorimetry to determine the relationship between energy expenditure and ambient temperature over a range of temperatures that pygmy rabbits experience in their natural habitat. We also measured the temperature of above- and below-ground rest sites used by pygmy rabbits in eastern Idaho, USA, during summer and winter and estimated the seasonal thermoregulatory costs of resting in the two microsites. Although pygmy rabbits demonstrated seasonal physiological acclimatization, the burrow was an important thermal refuge, especially in winter. Thermoregulatory costs were lower inside the burrow than in above-ground rest sites for more than 50% of the winter season. In contrast, thermal heterogeneity provided by above-ground rest sites during summer reduced the role of burrows as a thermal refuge during all but the hottest periods of the afternoon. Our findings contribute to an understanding of the ecology of small mammals in seasonal environments and demonstrate the importance of burrows as thermal refuge for pygmy rabbits

A Statewide Evaluation of Fuel Treatment Effectiveness in Altering Wildfire Outcomes on Public Lands in Utah

Fuel treatments are land management activities that reduce living and dead flammable materials on the landscape to mitigate undesirable wildfire behavior and effects. Common treatments in the western United States include mechanical methods such as thinning and mastication, prescribed burns, and chemical methods, such as herbicide application. Treatments usually have multiple objectives, including reducing fire intensity, protecting natural and cultural resources, slowing or disrupting a potential future fire’s path, supporting ecosystem health, and reestablishing low to mid severity fire cycles in ecosystems. Although treatments can potentially modify fire behavior and ecological health, they generally cannot prevent fires from igniting, eliminate fires from occurring, or consistently stop active fires from spreading. The majority of fuel treatments are never encountered by wildfire, which limits our understanding of effectiveness. In Utah, treatments are primarily implemented by the U.S. Department of the Interior Bureau of Land Management (BLM) and U.S. Department of Agriculture Forest Service (USFS). In order to increase understanding of fuel treatment effectiveness, I conducted a statewide study, including 3,208 fuel treatments and 1,558 wildfires on BLM and USFS managed lands across Utah from 1997 to 2019. The objective of my study was to evaluate treatment effectiveness using four metrics: 1.) Encounter rates, 2.) Burn severity, 3.) Manager reports and 4.) Ecological health. In Chapter 2, I summarized treatment and wildfire distributions and calculated a treatment encounter rate of 8.7%. I also analyzed burn severity in 48 treatments in forested vegetation, finding that treatments significantly reduced burn severity, especially in areas that had been treated repeatedly. Finally, manager observations from treatments encountered by fire were summarized, with findings that managers reported fuel treatments to be effective in the majority of encounters. Chapter 3 evaluated ecological health in juniper mastication treatments, using field measurements, and found no treatment effect on cheatgrass, bare ground, or sagebrush density post-fire. In conclusion, fuel treatments were effective in their primary goals of altering fire behavior and effects, based on the metrics of burn severity and manager reports. However, fuel treatments were seldom encountered by wildfire, and juniper mastication treatments were ineffective at improving the measured ecological health metrics. These findings suggest that expanding treated areas to improve encounter rates will increase the circumstances in which treatments are effective

The influence of climate and land cover on wildfire patterns in the conterminous United States

The occurrence of wildfires is greatly dependent on an ecoregions typical climate and land cover type. To investigate whether climate or land cover primarily lead to wildfires in the conterminous United States, wildfire events from 1999- 2010 are analyzed. Wildfires are divided into years and eco-divisions, a sub-form of ecoregions. To assess whether warmer and dryer divisions are more severely affected by wildfires, the characteristic fire size is determined for every division. Smaller to medium sized fires are found to contribute most to the area burnt but no relationship between the fire size and the climate could be found. The Nesterov Fire Index, Growing Degree Days and precipitation are calculated for all years at a 0.5° resolution and are pooled together with elevation, the fractions of land cover classes and the area burned per cell. Envelopes are created for all factors to assess the threshold from whereon fire bigger than 700m2 are not affected by fire anymore. Fire events seem to occur randomly, whereby evergreen forest and shrub land are identified to burn easily. A Pearson correlation is performed between the parameters but only weak correlations are found. A weighted logistic regression is then carried out to test if more significant results are present when applying a GLM-model. Only slightly better correlations are found whereby the Nesterov Index scores as the best factor. A model selection is then done to inspect which factors explain the occurrence of wildfires best. Again the Nesterov Index scores as the best predictor, followed by the "others" land cover class (infrastructure, barren land, water bodies), evergreen forest and the GDD. The impact of these factors is not strong enough to conclude that climate or land cover is determined to be the dominant factor causing wildfires. However, climate sets the frame on where fires might occur and where they certainly do not. More factors over a longer time period and on a smaller scale must be taken into account to predict the wildfire occurrence.Fuel, an ignition source and dry conditions must be available for a fire to ignite. The occurrence of wildfires thus greatly depends on the ecoregions with its typical climate and land cover. To investigate if climate or land cover primarily lead to wildfires in the conterminous United States, wildfire events from 1999- 2010 are analyzed. To assess if warmer and dryer divisions are more severely affected by wildfires, the characteristic fire size is determined for every division. This is the fire size which contributes most to the total area burned. Smaller to medium sized fires are found to be the main contributors but no relationship with climate could be found. The U.S. is divided into small cells (0.5° resolution). The Nesterov Index (an index which indicates the danger for a fire to ignite), Growing Degree Days (measures the growth of vegetation) and precipitation are calculated for all years and each cell. They are pooled together with elevation, the fractions of land cover classes and the area burned per cell. For each factor, the maximum and minimum value where a fire is detected are determined to assess the thresholds where fires certainly do not burn anymore. Fire events seem to occur randomly, whereby evergreen forest and shrub land are identified to burn easily. Almost no effect of the factors on the occurrence of fires is measured when carrying out a regression analysis. The Nesterov Index scores best, followed by the "others" land cover class (infrastructure, barren land, water bodies), evergreen forest and GDD. The impact of these factors is not strong enough to conclude that climate or land cover is determined to be the dominant factor causing wildfires. More factors over a longer time period and on a smaller scale must be taken into account to predict the wildfire occurrence

Environmental Superstatistics

A thermodynamic device placed outdoors, or a local ecosystem, is subject to a variety of different temperatures given by short-tem (daily) and long-term (seasonal) variations. In the long term a superstatistical description makes sense, with a suitable distribution function f(beta) of inverse temperature beta over which ordinary statistical mechanics is averaged. We show that f(beta) is very different at different geographic locations, and typically exhibits a double-peak structure for long-term data. For some of our data sets we also find a systematic drift due to global warming. For a simple superstatistical model system we show that the response to global warming is stronger if temperature fluctuations are taken into account.Comment: 37 figures. Significantly extended version, to appear in Physica A. Added new material in section 6 quantifying the stronger response to global warming if temperature fluctuations are taken into account. Concluding section 7 and several new references adde

The use of high altitude remote sensing in determining existing vegetation and monitoring ecological stress

High altitude color and multispectral black and white photography was used to survey existing vegetation and soil conditions on the Empire Ranch where large scale development will soon begin. Utilizing stereo pairs of the high altitude color photography, four vegetation classifications were discernable as a function of topography and foliage characteristics. In contrast to the undeveloped Ranch, the same photography was used to detect environmental changes in the Tucson metropolitan area as a result of rapid urbanization. The most prevalent change related to development is the removal of vegetation in high density areas to allow for housing starts. Erosion then occurs where vegetation has been removed

Refugee perceptions of the role of climate change in their migrations to Europe

Forced migration and climate change are two of the most pressing issues humanity faces today, that will continue to need addressing in coming decades as they are predicted to grow in scale. Migration can be viewed as an adaptation response to climate shifts, and there can often be a direct link as in the case of storms or drought; however, it is extremely difficult to accurately quantify the role climate change is playing in these movements as there are complex factors at play. More often than not, climate is only one reason (of many) why people leave their homes, or it is a subtle contributor to wars and tensions that cannot necessarily be proven. This research aims to fill in some of the gaps in understanding the climate-migration nexus, i.e. if climate change is a contributing factor in forced migration, and to what extent refugees believe this to be the case. There is a plethora of literature based on expert opinions and abstract predictions as to the amount of climate refugees there truly are or will be in the future, but this study aims to get the refugee perspective on the matter. This mixed methods analysis will dissect and try to gauge what percentage of refugees in Europe believe climate to be a reason they left, how it played a role (water scarcity, agricultural difficulties, heat waves, etc…), in which regions (Middle East, North Africa, Sub-Saharan Africa…) it was most a factor, and if it continued to play a role on their journeys to Europe. The study will then go deeper on these reasons, examining the discrepancies between refugee perceptions and scientific projections, and take a case study approach with certain interviews that have the depth to do this. This will be conducted remotely and in person in Greece. The study aims to utilize a broad sample size of many nationalities to get a general idea of how prevalent “climate refugees” are among the refugee populations of Europe, by their own definition. Results of this study found that 93% of interviewees did not believe climate change had played a role in their migration, but alternatively 59% also believed that climate change is a reason people migrate from their country in general. Perceptions of climate change impacts in the regions of the Middle East, Sahel, Sub-Saharan Africa, and the Horn of Africa found that most of the interviewees did believe climate impacts were affecting their country, and were sometimes leading to migration, often in conjunction with other social and political factors. The perceptions often aligned with the physical science data, although not always, and sometimes there was opposition, while other times data and certainty was lacking. Changes in precipitation, water scarcity, and agricultural difficulties were the primary impacts mentioned, and associated with migration. Other impacts and drivers are discussed in the paper as well. This study provides interesting insight into climate migration perceptions of the refugee population in Europe

Increased Abundance of the Common Raven Within the Ranges of Greater and Gunnison Sage-grouse: Influence of Anthropogenic Subsidies and Fire

The common raven (Corvus corax; raven) is native to North America and has increased in abundance, especially throughout western North America, during the last century. Human subsidies have facilitated raven dispersal into less suitable habitats and enabled these populations to maintain higher annual survival and reproduction. Concomitantly, overabundant raven populations are impacting other native at-risk species such as the greater sage-grouse (Centrocercus urophasianus) and potentially the Gunnison sage-grouse (C. minimus). Using Breeding Bird Survey data from 1995–2014, we evaluated raven count data to quantitatively describe changes in abundance and expansion into sagebrush (Artemisia spp.) ecosystems, specifically sage-grouse habitat. We focused our analyses on the 7 sage-grouse management zones (MZs) delineated across 11 western U.S. states and 2 Canadian provinces. We assessed the effects of land cover and anthropogenic disturbance on instantaneous growth rate (r) or carrying capacity (K) of ravens. Abundance of ravens in western and southeastern MZs was greater than northeastern MZs within the greater sage-grouse range. While raven abundance was lower in MZ I and II (Alberta, Canada; Dakotas, Montana, and northwestern Colorado, USA; Saskatchewan, Canada; and Wyoming, USA), raven expansion and percent increase were equivalent or greater than all other MZs. High abundance in MZ VII indicated Gunnison sage-grouse have been exposed to increased raven populations for several decades. Areas with greater electric power transmission line density had higher r; higher K was positively related to proportion of urban land cover within 25 km and burned area within 3 km and negatively related to greater distance from landfills and proportion of forest land cover within 15 km. Ravens have capitalized on human subsidies to increase abundance and expand into sagebrush ecosystems that did not historically support high raven populations. As such, managers are now faced with a new dilemma of reducing populations of a native species to benefit other native sagebrush obligate species