High Winter Precipitation Research Articles

Палеоэкологические условия финала сарматской эпохи и их влияния на общества скотоводов и земледельцев Восточной Европы и Западной Сибири

The paper make an attempt to consider the cultural and historical events marking the final stage of the Sarmatian epoch from the point of view of climate dynamics in Eastern Europe. It has been confirmed that the Late Sarmatian period in the Lower Volga region coincided with increasing climate humidity and was characterized by high precipitation during the cold season. This occurred in conditions of the Siberian High weakening, resulted to penetration of the Atlantic and Mediterranean cyclones into the inland regions of Eastern Europe and the western areas of Western Siberia. This led to high snow cover formation and provoked a series of other unfavorable factors that triggered migrations and population decline in nomadic or semi-nomadic societies whose economic basis was cattle herding. We suppose that this climate change scenario was not limited to the Lower Volga region. In the article we analyze paleoclimatic, cultural and historical events of the 3rd – 4th centuries AD which occured in the adjacent regions. We found that during this period the Sargat culture, whose economy was based on semi-nomadic cattle breeding, was declining in most of the forest-steppe east of the Urals. The population in the Southern Urals almost completely disappeared by the last decades 3rd century AD. The area of the Late Sarmatian culture from the Lower Volga region is reduced to the Astrakhan Right Bank of the Volga. Only the Lower Don and the Sal-Manych steppes remained inhabited, which is probably due to the regional resource base specifics. Therefore, in most part of Eastern Europe and the western regions of Western Siberia, the population was declining or disappearing long before the Huns invasion, and increase in climate humidity was among the contributing factors. At the same time, the humid climate of the 3rd – 4th centuries AD had a beneficial impact on the crop production. A high winter precipitation provided the flourish of agricultural societies.

Breeders’ age, nest-site characteristics and climatic conditions but not density-dependent effects determine Bonelli’s Eagle breeding performance: A long-term study (2002–2021)

Abstract The conservation of endangered species is a crucial topic in conservation biology due to the important ecological roles these species play in their respective ecosystems. Top predators are particularly vulnerable to the variation in environmental conditions. The Bonelli’s Eagle (Aquila fasciata) is a long-lived bird of prey that fulfills its role as a top predator in Mediterranean ecosystems, but its overall population has declined in the Iberian Peninsula in recent decades. As with other long-lived species, the Bonelli’s Eagle reaches its maximum fitness at maturity, highlighting the importance of assessing how intrinsic and extrinsic factors affect population dynamics over time. In this study, we conducted annual surveys of a Bonelli’s Eagle subpopulation in the eastern Iberian Peninsula from 2002 to 2021. Our results indicate that the large decline observed in the number of occupied territories, fledged chicks, and successful pairs is not due to negative density-dependent effects but rather influenced by various environmental and demographic factors. These factors include breeders’ age, nest-site characteristics, climatic conditions, and previous breeding costs. We found that productivity was higher in territories with high winter precipitation and temperatures, as well as in coastal areas, leading to earlier laying dates. Additionally, the presence of subadult individuals in the breeding pair decreased breeding performance. Interestingly, the variability in the number of fledglings in each territory was driven by previous breeding costs. Prioritizing efforts to mitigate adult mortality and conserve suitable habitats becomes imperative to halt the ongoing decline of this population and also to enhance productivity, ultimately facilitating the restoration of the species to previous population levels.

Water dynamics of cover crops: No evidence for relevant water input through occult precipitation

AbstractRising temperatures and disruption of rainfall patterns due to climate change make water a limiting growth factor even in regions of temperate climates. Thus, producing ‘more crop per drop’ is of utmost importance. While cover crops provide many benefits to cropping systems, their influence on soil water is discussed controversially. While an increase in transpiration can lead to soil water depletion, the reduction of evaporation in combination with possible additional water inputs could provide a water benefit for a succeeding crop. Occult precipitation could be such an additional water input. The objective of this study was to quantify whether cover crops provide a net water benefit over a bare fallow due to the occurrence of occult precipitation. In a 2‐year experiment, seven different cover crops were cultivated in pure stands and as a mixture under semi‐controlled conditions in a container experiment. Water fluxes and meteorological conditions were closely monitored. Although favourable conditions occurred during both vegetation periods, we found no evidence of occult precipitation. In autumn, soil water was depleted by fast‐growing cover crops. In winter, soil water was recharged due to the early preparation of a mulch layer combined with high winter precipitation while in early spring rising temperatures increased transpiration losses of a winter‐hardy cover crop, leading to a reduction of soil water. For middle European conditions, this shows that (1) living cover crops do not provide any water benefits and that (2) soil water recharge in winter is highly dependent on meteorological conditions and cover crop management. From a water budget viewpoint, negative effects on a succeeding cash crop can only be prevented if cover crops are terminated early enough for replenishment of soil water.

Shifting climate conditions affect recruitment in Midwestern stream trout, but depend on seasonal and spatial context

AbstractClimate change is a complex threat to freshwater ecosystems. Effects on aquatic species will likely differ among populations depending on seasonal and spatial context, which makes a detailed understanding of population responses to shifting climate conditions key to guiding strategic decision‐making. However, few empirical studies have tested for such context dependency on distinct populations across seasons or at large spatial scales. We used 26 years of standardized survey data on recreationally and economically important brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) in Wisconsin, USA to assess short‐ and long‐term variability in population trends, and quantify the influence of seasonal and spatial climate variability (air temperatures and precipitation) on annual recruitment strength (as indexed by young‐of‐year [YOY] relative abundance in summer). Some short‐term population fluctuations were spatially consistent across the state, indicative of broadscale environmental forcing. Over the longer term, average YOY and age 1 and older brook trout relative abundance has declined since 2006, especially for YOY, while brown trout abundance has substantially increased. The effects of climate conditions on recruitment varied by species, season, and latitude. Increasing maximum summer temperatures were associated with lower brook trout recruitment, but higher brown trout recruitment. The effect for both species was stronger at lower latitudes. Spring temperatures were positively related to brown trout recruitment at lower latitudes; in mid‐latitude and northern streams, they were related to increasing recruitment up to about 1 standard deviation, above which recruitment declined. High and low winter and spring precipitation were associated with precipitous declines in recruitment for both species. By contrast, summer precipitation was positively related to recruitment in northern streams for brook trout and southern streams for brown trout. Our results demonstrate that shifts in climate can affect recruitment in similar species differently depending on temporal (seasonal) and spatial (warm, southern regions compared with cool, northern regions) context. Given trout population trends in Wisconsin and climate projections for the Midwestern United States, location‐ and species‐specific management actions are needed that account for this context dependency. Management should aim to maximize the resiliency of populations to extreme climate conditions by buffering negative influences on recruitment.

Quantifying the Trends and Drivers of Ice Thickness in Lakes and Rivers across North America

Monitoring the timing of ice-on and ice-off has been instrumental in estimating the long-term effects of climate change on freshwater lakes and rivers. However, ice thickness has been studied less intensively, both spatially and temporally. Here, we quantified the trends and drivers of ice thickness from 27 lakes and rivers across North America. We found that ice thickness declined on average by 1.2 cm per decade, although ice thickness declined significantly in only four waterbodies. Local winter air temperature, cloud cover, and winter precipitation were the most important determinants of ice thickness, explaining over 81% of the variation in ice thickness. Ice thickness was lower in years and regions with higher air temperatures, high percentage of cloud cover, and high winter precipitation. Our results suggest that warming is contributing to thinning ice, particularly at high latitudes, with potential ramifications to the safety of humans and wildlife populations using freshwater ice for travel and recreation.

Precipitation Variability and Probabilities of Extreme Events in the Eastern Mediterranean Region (Latakia Governorate-Syria as a Case Study)

This study aimed at analysis of the general-index change for the mean annual and seasonal precipitation in six stations in Latakia Governorate (Syria). The data of precipitation were collected for 40 consecutive years (1970–2010) in order to figure out the extent of the changes and variability in precipitation rates and the impact of this change on changes in the potential density that might cause extremely high or low precipitation rates according to Gumbel distribution of the extreme precipitation rates. Results revealed a decrease of the annual precipitation rates in all stations, the reduction in precipitation ranged from 46 to 210 mm during the whole period of the study. Spring, however, recorded the highest and statistically significant reduction, which reached 46–210 mm, while winter precipitation increased by 21–82 mm. Spring also has witnessed a decrease of about 3–9% of the total annual precipitation as compared to winter precipitation which increased by 5–8% of the total. The potential density of extremely high winter precipitation rates increased in all stations as indicated from Gumbel distribution in winter, and a greater increase took place in the probabilities of occurrence of the extremely low spring precipitation rates. This shows significant probability of occurrence of drought during spring season. By contrast, probabilities of winter precipitation rates increased more, thus winter is relatively more humid than before and spring is relatively drier than before.

Genetic, Morphological, and Environmental Differentiation of an Arid-Adapted Oak with a Disjunct Distribution

The patterns of genetic and morphological diversity of a widespread species can be influenced by environmental heterogeneity and the degree of connectivity across its geographic distribution. Here, we studied Quercus havardii Rydb., a uniquely adapted desert oak endemic to the Southwest region of the United States, using genetic, morphometric, and environmental datasets over various geographic scales to quantify differentiation and understand forces influencing population divergence. First, we quantified variation by analyzing 10 eastern and 13 western populations from the disjunct distribution of Q. havardii using 11 microsatellite loci, 17 morphological variables, and 19 bioclimatic variables. We then used regressions to examine local and regional correlations of climate with genetic variation. We found strong genetic, morphological and environmental differences corresponding with the large-scale disjunction of populations. Additionally, western populations had higher genetic diversity and lower relatedness than eastern populations. Levels of genetic variation in the eastern populations were found to be primarily associated with precipitation seasonality, while levels of genetic variation in western populations were associated with lower daily temperature fluctuations and higher winter precipitation. Finally, we found little to no observed environmental niche overlap between regions. Our results suggest that eastern and western populations likely represent two distinct taxonomic entities, each associated with a unique set of climatic variables potentially influencing local patterns of diversity.

Föhn, fire and grazing in Southern Tibet? A 20,000-year multi-proxy record in an alpine ecotonal ecosystem

The lithology, ostracods, palynomorphs and black carbon of a sediment core from a saline wetland in the southern Tibetan highlands (29°14′33.40″N/87°13′09.10″E, 4480 m a.s.l., A.R. Xizang, China) is analyzed and climate modelling applied with respect to core questions in Quaternary research: (1) Do meso-climatic effects of regional landscape structures like high mountains overrule the effects of global climates? (2) Did life persist during the LGM? (3) Which shifts in ecosystems can be detected? (4) Does the fire-record testify for the presence of humans and their environmental impact? (5) How old is Neolithisation in the world’s largest highlands?The results of this integrated multi-disciplinary investigation revealed (1) the meso-climatic effect of the Himalayan arc’s relief channeled westerlies with West-Himalayan forest-pollen types into the southern Tibetan highlands, with (2) higher winter-precipitation, slightly lower summer precipitation, and the persistence of life for plants, and herbivores and therefore probably hunters. (3) The most arid period occurred between 17.8 and 15 cal kyr B.P., possibly synchronous with the Heinrich 1 event. Around 14.8 cal kyr B.P. humidity increased with torrential rains of high erosive power on sparsely plant-covered slopes and lasted until 4 cal kyr B.P. (4) The continuous fire-record proved the availability of combustible matter and a constant fire source which is believed to be human-attributed. Charcoal peaks around 17, 16 and 13 cal kyr B.P. remained sporadic until 11.5 cal kyr B.P. and attained the highest values since 8.7 cal kyr B.P. Black carbon increased steadily until 11 cal kyr B.P. and sharply peaked with high fluctuations around 10 cal kyr B.P., indicating high frequency intensive fires at the beginning of the Holocene. Between 10 and 6 cal kyr B.P. fire frequency decreases, with a slight peak around 4 cal kyr B.P. (5) The dawn of pastoralism in the early Mid Holocene Climatic Optimum dated back to 8.7 cal kyr B.P. with a decline of grass-pollen and the synchronous emergence of grazing weeds, leaving a perception gap of 5000 years between the palaeo-ecological and the archaeological state of the art.

Carbon Dioxide Fluxes of a Young Deciduous Afforestation Under the Influence of Seasonal Precipitation Patterns and Frequent Typhoon Occurrence

AbstractAfforestation is considered a major tool for climate change mitigation with high potential particularly in the tropics. In this study we analyzed CO2 fluxes of an afforested former sugar cane plantation in southern Taiwan, as this forest had been planted with the goal of sequestering CO2 to help mitigate climate change. The plantation is exposed to a monsoon climate with dry but warm winter seasons, heavy precipitation during the summers and experiences a rather high frequency of typhoons (0.7 per year). The aim of this study is to quantify the net ecosystem exchange (NEE), ecosystem respiration (ER), gross primary production (GPP) and increment in above‐ground biomass (AGB) at the site. Specifically, we aim to analyze the influence of the distinct wet and dry seasonality and the frequent typhoon impact on these fluxes. We estimated the CO2 fluxes for two years using the eddy covariance approach. In 2010 and 2016 the forest sequestered carbon from the atmosphere with a NEE of −116 g C m−2 year−1 and −322 g C m−2 year−1, respectively. Between 2011 and 2014, the yearly increment in AGB increased with a mean increment of 509 ± 181 (SD) g C m−2 year−1. We observed high seasonal difference in CO2 fluxes particularly in ER and GPP, and conclude that high winter precipitation enhances CO2 uptake. Furthermore, frequent typhoons reduced the CO2 uptake and increment in AGB, such as in 2016, when a very strong typhoon passed the forest.

Holocene precipitation seasonality in northern Svalbard: Influence of sea ice and regional ocean surface conditions

Arctic precipitation is predicted to increase in the coming century, due to a combination of enhanced northward atmospheric moisture transport and local surface evaporation from ice-free seas. However, large model uncertainties, limited long-term observations, and high spatiotemporal variability limit our understanding of these mechanisms, emphasizing the need for paleoclimate records of precipitation changes. Here we use lipid biomarkers in lake sediments to reconstruct precipitation seasonality in northern Spitsbergen, Svalbard. We measured the hydrogen isotopic ratios (δ2H) of n-alkanoic acids (C20–C30) from sedimentary leaf waxes in lake Austre Nevlingen, Spitsbergen. We interpret δ2H values of mid-chain (C22) and long-chain (C28) n-alkanoic acids to represent δ2H of lake and soil water, respectively. Austre Nevlingen lake water δ2H reflects amount-weighted mean annual precipitation δ2H. In contrast, soil water is mostly recharged by summer rainfall, and therefore reflects δ2H values of summer precipitation. Austre Nevlingen leaf wax δ2H values are 2H-depleted in the Early Holocene, suggesting high winter precipitation amounts. This coincides with high summer insolation, strong Atlantic water advection and reduced spring sea-ice cover in surrounding waters. Winter precipitation continued to dominate until c. 6 cal. kyr BP. After 6 cal. kyr BP, the trend in the biomarker record is not as clear. This could be related to colder conditions causing longer duration of seasonal lake-ice cover, thereby influencing the precipitation seasonality registered by the lake water. The Austre Nevlingen record suggests a close relationship between precipitation seasonality and regional ocean surface conditions, consistent with simulations suggesting that Arctic winter sea-ice loss will lead to increased local evaporation.

Evaluating historical trends and influences of meteorological and seasonal climate conditions on lake chlorophyll a using remote sensing

Hansen CH, Burian SJ, Dennison PE, Williams GP. 2019. Evaluating historical trends and influences of meteoorological and seasonal climate conditions on lake chlorophyll a using remote sensing. Lake Reserv Manage. 36:45–63.Evaluations of long-term water quality trends and patterns in lakes and reservoirs are often inhibited by irregular historical records. This study uses historical Landsat satellite imagery to construct a more complete historical record of algal biomass (measured via chlorophyll a [Chl-a]) and presents a framework for developing seasonal algal estimation models using open source tools for processing and model development. This approach is both physically based (using observed patterns of variability and algal succession in the lake) and data driven (relying on statistical methods for model development). We use a generalized linear regression modeling technique to develop lake-specific, seasonal models for each lake in the multilake Great Salt Lake system in Utah. The 32-yr constructed history of estimated Chl-a enables analysis of long-term trends within the lake system as well as evaluations of local climate influences on Chl-a concentrations. The estimated historical record exhibits a shift in seasonality (i.e., maximum Chl-a occurs earlier in the growing season), as well as increasing trends of extreme Chl-a concentrations. We also evaluated relationships between meteorological conditions and Chl-a using the enhanced historical record and found localized sensitivity to short-term weather events such as high wind, high temperatures, or precipitation events. Seasonal climate conditions including high winter precipitation, summer temperatures, and early spring snow water equivalent are consistent with higher Chl-a extremes in the historical record. Improved understanding of the trends and climate influences provides useful context and guidance for future monitoring efforts and management strategies.

Scale effects of topographic ruggedness on precipitation over Qinghai‐Tibet Plateau

AbstractDue to the complex topography in mountainous areas, the pattern of precipitation is impacted by the topographic ruggedness (TR) that is characterized from Digital Elevation Model and thus scale‐dependent. Scale effects on the precipitation–TR relationship have not been well known in the Qinghai‐Tibet Plateau. Based on station measurements of precipitation in the domain, this study uses the quantile regression method to investigate the response of precipitation quantiles in summer and winter to the TR changes at different spatial scales. It is found that the scale variations impede the validity analysis of precipitation–TR relations. Neither too large (>100 km) or too small (<1 km) scales are suitable for exploring summer precipitation, and the scales are better less than 30 km for high winter precipitation. The analyses address that the precipitation–TR relations depend on appropriate spatial scales, which is important for statistical downscaling and model projection of precipitation in the Qinghai‐Tibet Plateau.

Revisiting the dynamic and thermodynamic processes driving the record-breaking January 2014 precipitation in the southern UK

Many attribution studies of precipitation extreme events have attempted to estimate the thermodynamic contribution (linked to temperature changes) and the dynamic contribution (linked to the atmospheric circulation). Those studies are based on statistical decompositions of atmospheric fields, and essentially focus on the horizontal motion of the atmosphere. This paper proposes a framework that decomposes those terms from first physical principles, which include the vertical atmospheric motion that has often been overlooked. The goal is to take into account the driving processes of the extreme event. We revisit a recent example of extreme precipitation that was extensively investigated through its relation with the atmospheric circulation. We find that although the horizontal motion plays a minor (but important) role, the vertical motion yields a dominating contribution to the event that is larger than the thermodynamic contribution. This analysis quantifies the processes leading to high winter precipitation rates, and can be extended for further attribution studies.

Value of a Limited Number of Discharge Observations for Improving Regionalization: A Large‐Sample Study Across the United States

AbstractEven in regions considered as densely monitored, most catchments are actually ungauged. Prediction of discharge in ungauged catchments commonly relies on parameter regionalization. While ungauged catchments lack continuous discharge time series, a limited number of observations could still be collected within short field campaigns. Here we analyze the value of such observations for improving parameter regionalization in otherwise ungauged catchments. More specifically, we propose an ensemble modeling approach, where discharge predictions from regionalization with multiple donor catchments are weighted based on the fit between predicted and observed discharge on the dates of the available observations. It was assumed that a total of 3 to 24 observations from a single hydrological year were available as an additional source of information for regionalization. This informed regionalization approach was tested with discharge observations from 10 different hydrological years in a leave‐one‐out cross validation scheme on 579 catchments in the United States using the HBV runoff model. Discharge observations helped to improve the regionalization in up to 94% of the study catchments in 8 out of 10 discharge sampling years. Sampling years characterized by exceptionally high peak discharge, or high annual or winter precipitation were less informative for regionalization. In the least informative years, model efficiency increased with an increasing number of observations. In contrast, in the most informative sampling year, 3 discharge observations provided as much information for regionalization as 24 discharge observations. Overall, discharge observations were most effective in informing regionalization in arid catchments, snow‐dominated catchments, and winter‐precipitation‐dominated catchments.

Wet avalanches: long-term evolution in the Western Alps under climate and human forcing

Abstract. Understanding wet avalanche intensity and the role of past environmental changes on wet avalanche occurrence is a main concern especially in the context of a warming climate and accelerated environmental mutations. Avalanches are closely related to fast cryosphere changes and may cause major threats to human society. Here, we used the sedimentary archive of the Alpine Lake Lauvitel (Lac du Lauvitel; western French Alps) to establish the first long-term avalanche record in this Alpine region. For this purpose, we used a novel CT-scan methodology that allows the precise identification of coarse material – from sand to pebble – transported to the lake and embedded within the finer continuous sedimentation. We identified a total of 166 deposits over the last 3300 yr cal. BP. In parallel, a detailed pollen analysis gave an independent record of environmental changes. Based on modern observation, lake monitoring, seismic investigations and sedimentological evidences, coarse material deposits were attributed to wet avalanche events. Our results highlight the effect of vegetation cover on the avalanche hazard while a period of strong frequency increase occurred after 780 yr cal. BP. In Lake Lauvitel, this period corresponds to a major forest clearance induced by the rise of human land use. Climate forcing on the avalanche hazard was investigated before and after the vegetation shift. On a multicentennial scale, wet avalanches preferably occur during periods of larger glacier extent, in which higher winter precipitation probably generates a sufficiently thick snow cover. On a sub-centennial scale, avalanches are more frequent during periods of relative warming, resulting in a destabilization of the same snow cover in spring season. Our results highlight as well the role of forest cover in mitigating wet snow avalanches' occurrence. In the context of predicted warmer temperatures, this study raises the question of whether a wet avalanche hazard increase may be expected in the near future especially at higher altitudes.

Impacts of climate variability and change on seasonal drought characteristics of Pakistan

Assessment of the influence of climate variables on drought characteristics is important for adaption to changing pattern of droughts due to climate change. The objective of this study is to assess the changing characteristics of droughts due to climate variability and change during two major cropping seasons (Rabi and Kharif) for the period 1901–2010 over the diverse climate of Pakistan. The gauge-based gridded precipitation and temperature data with a spatial resolution of 0.5° is used for the reconstruction of droughts using standardized precipitation evapotranspiration index (SPEI). The temporal variations in droughts and their relationships with precipitation and temperature are assessed using a 50-year moving window with a 10-year time step. The annual maximum series (AMS) approach is used to estimate the return periods of seasonal droughts and the modified Mann-Kendal trend test is applied to assess the significance of trends in climate variables and drought index. The results showed that drought severity is increasing in the predominantly arid and semi-arid regions for both cropping seasons, while it is decreasing in western disturbance (WD) influenced high winter precipitation region during Rabi season. Temperature is found as the dominating factor for defining droughts in arid and semi-arid regions while the precipitation in WD influenced region. An increase in temperature in the range of 0.001 to 0.025 °C per year and almost no change in precipitation have caused decreases in Rabi SPEI in the range of −0.011 to −0.025 per year in the arid region. On the other hand, increases in precipitation in the range of 1.01–2.0 mm/year have caused increases in Kharif SPEI in WD influenced region in the range of 0.016–0.02 per year. However, rises in temperature in most part of the country has caused an increase in drought frequency in both seasons in the areas where droughts are less frequent. The results indicate that rising temperature due to global warming would increase drought severity and frequency in most part of the predominantly arid country.

Climate-sensitive radial increment model of Norway spruce in Tyrol based on a distributed lag model with penalized splines for year-ring time series

A novel methodological framework is presented for climate-sensitive modeling of annual radial stem increment using year-ring width time series. The approach is based on a generalized additive model with penalized regression splines together with a distributed time lag model taking into account smooth nonlinear effects of a series of monthly temperature and precipitation values, as well as their interactions. Climate effects are also assumed to vary smoothly with time lag. The model framework enables both the detrending of the individual time series and the regression modeling to be performed simultaneously in a single model step. The approach is applied to year-ring width time series of Norway spruce (Picea abies (L.) H. Karst.) trees in Tyrol, Austria. The marginal response curves show that tree growth is mainly promoted by high temperatures in late spring and early summer and by precipitation in fall and winter. Summer drought does not have a negative influence on the current year’s radial increment; however, when it is associated with high temperatures, it lowers the increment in the subsequent growth period. Higher winter precipitation in conjunction with lower temperatures has a positive effect. A significant non-climate related long-term growth trend is demonstrated, probably reflecting NOx and SO2 emission trends in Austria.

Seasonal resource acquisition strategies of a facultative specialist herbivore at the edge of its range

Understanding animal performance at range edges has gained increasing interest due to climate change, but most efforts have focused on specialist species. Studying the breadth and plasticity of generalist resource acquisition strategies will provide important insight into how mammals adapt to and persist under a variety of environmental conditions. The North American porcupine (Erethizon dorsatum) is a widely distributed generalist herbivore with special adaptations to harsh climates and low-quality diets. However, on the north coast of California, which has a mild climate and abundant vegetation, porcupine populations are patchily distributed and may be in decline. We studied seasonal resource use of porcupines in a coastal dune ecosystem by measuring changes in body mass, home range size, habitat selection, and diet. Both female and male porcupines lost body mass between summer and winter (= 8.3% and 17.2%, respectively), although less than reported elsewhere. Their home range sizes were 31% larger during summer than winter. Porcupines selected swales and marshes during the summer, when they fed primarily on willow leaves, and switched to conifer forests and coastal scrub during winter, when they fed on bark, conifer needles, and leaves of evergreen shrubs. Porcupines exploited 2 novel food sources common in Pacific coastal lowlands: coast manroot fruits and California wax myrtle leaves. We suggest that porcupines employ a similarly flexible resource acquisition strategy across their range, and although it appears to be broadly effective, they may face challenges from plant phenology, low broad-leaved tree diversity, and high winter precipitation in Pacific coastal climates.

Extreme Climate Effects on Dissolved Organic Carbon Concentrations During Snowmelt

AbstractExtreme weather and climate events are predicted to increase in frequency and severity in the near future, which could have detrimental consequences for water quality in northern latitudes. Key processes that regulate the production and transport of solutes, like dissolved organic carbon (DOC), from soils to streams can be potentially altered by episodes of extreme temperature and/or precipitation. Here we use an intensively studied research catchment in northern Sweden with 23 years of data to ask how extreme antecedent climate events influence DOC concentration during snowmelt. Specifically, we used a combination of principal components analysis, cluster analysis, and multivariate partial least square analysis to show that almost every year provides some combination of extreme conditions in terms of intensity, duration, or frequency of temperature and/or rainfall. However, in terms of DOC responses to these events, variations in peak concentrations were most closely related to cold winter conditions, winter precipitation (snow), and temperature during the previous autumn. Specifically, years with most severe frost and icing during winter, but low winter precipitation, previous summer precipitation, and warmer autumns, showed the highest peaks in concentrations. In contrast, the lowest peak DOC concentrations were observed during spring snowmelt following high summer precipitation, colder autumns, and high winter precipitation. While this research highlights the importance of winter climate for influencing the DOC concentration during the spring, it also points to the potential importance of lag effects from preceding seasons on responses observed during the snowmelt season.

The Geography of Glaciers and Perennial Snowfields in the American West

ABSTRACTA comprehensive mid-20th century inventory of glaciers and perennial snowfields (G&PS) was compiled for the American West, west of the 100° meridian. The inventory was derived from U.S. Geological Survey 1:24,000 topographic maps based on aerial photographs acquired during 35 years, 1955–1990, of which the first 20 years or more was a cool period with little glacier change. The mapped features were filtered for those greater than 0.01 km2. Results show that 5036 G&PS (672 km2, 14 km3) populate eight states, of which about 1276 (554 km2, 12 km3) are glaciers. Uncertainty is estimated at ±9% for area and ±20% for volume. Two populations of G&PS were identified based on air temperature and precipitation. The larger is found in a maritime climate of the Pacific Northwest, characterized by warm winter air temperatures and high winter precipitation (~2100 mm). The other population is continental in climate, characterized by cold winter air temperatures, relatively low winter precipitation (~880 mm), and located at higher elevations elsewhere. The G&PS in the Pacific Northwest, especially in the Olympic Mountains, are particularly vulnerable to warming winter air temperatures that will change the phase of winter precipitation from snow to rain, further accelerating glacier shrinkage in the future. Comparison with a recent inventory suggests that the total G&PS area in the American West may have decreased by as much as 39% since the mid-20th century.