Average Snowfall Research Articles

Numerical fluctuations in the northern short‐tailed shrew: evidence of non‐linear feedback signatures on population dynamics and demography

Summary We studied a fluctuating population of the northern short‐tailed shrew (Blarina brevicauda) in the Appalachian Plateau Province of Pennsylvania, USA, spanning 21 years of monitoring. We analysed the pattern of annual temporal variation fitting both time‐series models and capture–mark–recapture (CMR) statistical models for survival and recruitment rates. We determined that non‐linear first‐order models explain almost 80% of the variation in annual per capita population growth rates. In particular, a non‐linear self‐excited threshold autoregressive (SETAR) model describes the time‐series data well. Average snowfall showed positive and non‐linear effects on population dynamics. The CMR statistical models showed that a non‐linear threshold model with strong effects of population density was the best one to describe temporal variation in survival rates. On the other hand, population density or climatic variables did not explain temporal variation in recruitment rates. Survival rates were high during the study period. Weekly changes in population size attributable to new recruits entering in the population fluctuate between 21% and 0%, while the changes in population size related to survival fluctuate between 79% and 100%. Two important results arise from this study. First, non‐linear models with first‐order feedback appear to capture the essential features of northern short‐tailed shrew dynamics and demography. Secondly, climate effects represented by snowfall appear to be small and non‐linear on this insectivore. The population dynamics of this shrew in the Appalachian Plateau are determined apparently by a strong non‐linear first‐order feedback process, which is related to survival rates. This study links population dynamics and demography by detecting the underlying demographic mechanisms driving population dynamics. The feedback structure of this shrew suggests the existence of population dynamics dominated by intraspecific competitive interactions, such as aggression, solitary nesting, non‐overlapping home ranges and territoriality.

Twenty years of data on climate–permafrost–active layer variations at the lower limit of alpine permafrost, marmot basin, jasper national park, canada

In March 1979, a hole was drilled to a depth of 16.8 m through 1 m of till and loess into the clast‐supported boulders of a fossil Pre‐Late Wisconsin rock glacier just above tree line (2195 m elevation) at the Marmot Basin Ski Area, Jasper National Park (latitude 52∘47′36.5′′N, 118∘06′45.9′′W). Vegetation cover consists of a moist alpine meadow, on a bench which slopes gently to the south on the otherwise steep mountainside. The mean daily temperature for the site has been recorded continuously, and monthly readings have been made of ground temperatures using a thermistor string. Depth of the snow pack has been recorded on each visit, while November to April snowfall data are measured daily at 1985 m elevation. The mean annual air temperature (−2.38∘C) has decreased by about 0.7∘C since 1979, while the average winter snowfall (c. 310 cm) has increased by about 70 cm.A water table occurs at about 12 m depth with a water temperature of about 1.1∘C. Permafrost up to 6.8 m thick was present for almost all the period of study, with the active layer ranging from 2.2 to 4.3 m in depth. Temperatures in the permafrost varied seasonally, ranging down to −2.5∘C. The ground temperatures are constantly changing and are more closely related to thickness and duration of snow cover rather than air temperatures. The geothermal gradient averages 0.45∘ per metre in the upper 10 m, and there is a ‘thermal offset’ of about 4.1∘. Heat conduction is dominant at the surface, being replaced by closed‐cell convection between the blocks. In the early summer, warmer snow melt from the adjacent mountainside increases the thickness of the active layer and sometimes pierces the permafrost so that the warm water descends to the main water table below.

Performance of Two Nitrification Inhibitors Over a Winter with Exceptionally Heavy Snowfall

Fall application of NH3 for spring wheat (Triticum aestivum L.) is common in the northern Great Plains. Two field sites were established in eastern North Dakota, with the objective of measuring the relative rate of fall and overwinter nitrification as influenced by two nitrification inhibitors, nitrapyrin and ammonium thiosulfate (ATS). Aqua ammonia was injected into the soil in early October 1996, alone, with nitrapyrin (0.56 and 1.68 kg ha−1), or with ATS (17 kg S ha−1). The N rate was 84 kg ha−1. The winter of 1996–1997 was very unusual, with about 3 m of snowfall—three times the average snowfall in southeastern North Dakota. Nitrapyrin and ATS were effective in slowing nitrification in the fall and both inhibitors increased the amount of mineral N found in the fertilizer bands in the spring at both sites. One site was planted to ‘Pioneer 2375’ spring wheat. Overwinter N loss, presumably by denitrification, was severe. Amending the ammonia with nitrapyrin or ATS greatly increased wheat growth, N uptake, and grain yield. The apparent N uptake efficiency into the grain + straw was 24% for the unamended aqua ammonia, but was 50 to 56% when nitrapyrin or ATS was used. These results probably define a worst‐case scenario regarding the performance of fall‐applied ammonia in this area, and suggest that both nitrapyrin and ATS have value as nitrification inhibitors with fall‐banded N.

Relationship of ENSO to snowfall and related cyclone activity in the contiguous United States

The relationship of the El Niño‐Southern Oscillation to the contiguous U.S. snowfall was investigated using data from 3841 cooperative observer stations for the period 1951–1997. Snowfall for seven strong El Niño and five strong La Niña events was compared with snowfall occurring during the other 34 winters. The average snowfall for the seven El Niño winters exhibits a coherent large‐scale pattern with below‐average snowfall across approximately the northern half of the United States and above‐average snowfall over the southwestern United States. Application of the t‐test indicates that these snowfall anomalies are significantly different (at the 10% level) from the base period snowfall in parts of the mid‐Mississippi River basin, the northern Ohio River basin, the western Great Lakes, and the northwestern United States. During strong La Niña winters, above‐normal snowfall occurs in the northwest United States and northern Great Lakes. Although these anomalies do not pass tests of statistical significance (at the 10% level), the difference between La Niña and El Niño years is quite notable in the northwest United States. The results suggest that useful long‐range outlooks of snowfall anomalies are possible for certain areas of the contiguous United States during strong El Niño events. An analysis of the frequency of strong cyclones (central pressure <992 hPa) shows that the El Niño winters were characterized by above‐normal frequency in the extreme southern United States and below‐normal frequency along the U.S.‐Canadian border, with the pattern approximately reversed in the La Niña winters.

Survival and Habitat Use by Ring-Necked Pheasants during Two Disparate Winters in South Dakota

Severe winter weather in the Northern Great Plains of North America can alter availability of winter cover and cause increased mortality of ring-necked pheasants (Phasianus colchicus). We monitored pheasant survival and habitat use via radiotelemetry during the second most severe winter in eastern South Dakota since 1892. We captured and radiomarked 48 female ring-necked pheasants at the onset of the 1996-97 winter and monitored survivors through spring at 3 sites in eastern South Dakota. We also monitored 58 female ring-necked pheasants at the same sites during the 1995-96 winter, a winter characterized by below average temperature and average snowfall (winter severity rank: 35th). Survival of radiomarked hens in 1995-96 (0.61 [SE = 0.07]) was higher (P 75 cm), cattail (Typha spp.) wetland, and corn food plot habitats in winter 1995-96, and early winter 1996-97. Shelterbelt and corn food plot ranked highest for pheasants that survived to the second half of the 1996-97 winter. We conclude that shelterbelt and food plot habitats are essential to the survival of pheasants in eastern South Dakota during extreme winter weather conditions.

Winter methane dynamics in a temperate peatland

Methane (CH4) dynamics in pore water, snow pore air, and surface emissions were investigated in a temperate poor fen in New Hampshire over several winters. Total snowfall and average air temperatures during winter months (defined as December, January, and February) were climatologic indicators of significant flux rates from this midlatitude poor fen. Average winter emissions, for the five winters ending in 1994–1995, were 20, 39, 53, 56, and 26 mg m−2 d−1, amounting to 2.0, 5.2, 6.6, 9.2, and 2.0% of the total annual fluxes, respectively. Totaling emissions over 5 years that represent low to average snowfall, winter accounted for 4.3% of emissions to the atmosphere. Winter flux rates were near 55 mg m−2 d−1 for years with average snowfall, and 25 mg m−2 d−1 for years with low snowfall. Concentrations of CH4 sampled in pore water immediately beneath the ice were highly variable (0 to 1.1 mM). The concentration magnitude and standard deviation increased toward the fen center and correlated with spatial variation in hydrology, peat texture, and peat depth. CH4 stores increased in the near‐surface pore water as the ice cover formed. Seasonal CH4 buildup in deeper peat began near the end of the growing season, probably due to changing transport mechanisms and temperature effects on solubility. Stored CH4 in the 25‐ to 75‐cm peat layer decreased by 2.7 g m−2 between January and June 1995.

Seasonal habitat use and movements of woodland caribou in the Omineca Mountains, north central British Columbia, 1991-1993

From 1991 to 1993, 30 woodland caribou were captured and fitted with radio-collars west of the Williston Reservoir in north central B.C. Monthly radio-telemetry location flights revealed that caribou in the Northern Area, characterized by a complex of mountain ranges, moved greater distances to calving areas than did those in the South, where only one major mountain range exists. In the year of record heavy snowfall for the area, all collared caribou wintered on windswept alpine slopes, while during the below average snowfall year, many caribou remained in forested habitats. In winter, caribou were found to forage on terrestrial lichens in both lowland lodgepole pine flats and on windswept alpine slopes, and on arboreal lichens in upper elevation Engelmann spruce and subalpine fir forests. There are at least 600-700 caribou in the Omineca Mountains.

Winter methane dynamics beneath ice and in snow in a temperate poor fen

AbstractThe influence of winter on methane (CH4) stored in pore water and emitted through snow was investigated in a temperate poor fen in New Hampshire over two winters. Methane accumulated beneath ice layers (1 cm) deposited by freezing rain, resulting in snow‐pore air mixing ratios as high as 140 ppmv during the first winter and 600 ppmv during the second. An early winter snow crust of 300 kg m−3 caused no discontinuity in a linear mixing ratio profile and therefore was not observed to retard snowpack emissions. Methane concentration‐depth profiles in pore water steepened and concentrations increased by as much as 400 μM at the 10 and 20 cm depths as the ice cover formed. This suggests that the peat‐ice cover plays an important part in CH4 build‐up in pore water by limiting the transport of gases between the peat and the atmosphere. Pore water concentrations gradually declined through late winter. The seasonality of dissolved CH4 in pore water over two winters and one summer showed an average annual amplitude of 1.3 gCH4m−2 (25–75cm depth range), with a winter maximum of 4.7gCH4m−2. Emissions during the winter with average snowfall accounted for a larger percentage (9.2% in 1993–1994) of total annual emission than the winter with below‐average snowfall and warmer air temperature (2% in 1994–1995). Emissions averaged 56 and 26mg m−2 day−1 during the first and second winter (December, January and February), respectively.

Spatiotemporal Trends in Lake Effect and Continental Snowfall in the Laurentian Great Lakes, 1951–1980

Abstract A new raster-based monthly snowfall climatology was derived from 1951–1980 snowfall station data for the Laurentian Great Lakes. An automated methodology was used to obtain higher spatial resolution than previously obtained. The increase in resolution was attained by using all available monthly snowfall data from over 1230 stations per year combined with a monthly lime step to produce high-resolution grids. These monthly grids were combined to produce snow-year grids. Multiyear average grids were created and compared. This technique minimizes traditional problems associated with missing data and variable length station records. The three 10-year average distribution maps presented here indicate a period of increasing snowfall. Windowing of the 30 seasonal grids revealed that increasing snowfall was attributable to an increase in lake effect snowfall and not to continental snowfall. The Great Lakes drainage basin was evaluated for trends within and between monthly and seasonal average snowfall thr...

Salt lake at record levels

Utah's Great Salt Lake rose 1.6 m between September 1982 and June 1983, the greatest seasonal rise measured in 136 years of record, according to a report published by Ted Arnow, chief of the U.S. Geological Survey (USGS) Water Resources District Office in Salt Lake City. The lake, which continued to rise after Arnow wrote his report, rose 25 cm in December, a record for a 1‐month period. On January 1 the lake's height was measured at 1282.03 m above sea level, the highest since 1887.The combined effects of above average rainfall in 1982, above average snowfall in the autumn of 1982 and the spring of 1983, and unseasonably cool weather during the spring of 1983 led to the record rise.

Post-Release Movements of Introduced Marten

The U.S. Forest Service and the Wisconsin Department of Natural Resources released 124 marten (Martes americana) (97 males, 27 females) into the Fisher Management Unit (FMU) of the Nicolet National Forest between 26 January 1975 and 3 April 1976. Twenty-one marten (9 males, 12 females) were radiocollared to evaluate: (1) effects of 2 release methods, (2) release movements, and (3) reproduction. Postrelease movements for the 30-day period after release were significantly less for gentle-release (G-R) than for quick-release (Q-R) radio-collared marten. The G-R marten were held for a minimum of 1 week in pens placed throughout the FMU; Q-R marten were released directly from shipping containers. Six radio-collared marten moved out of the FMU by June 1976; maximum straight line movement in a 24-hour period was 22.0 km. Home range estimates for 2 females were 8.2 (N = 170) and 7.7 km2 (N = 42). No evidence of reproduction was documented. Marten are easily live-trapped and transported to parts of their former range provided accepted animal husbandry practices are followed. J. WILDL. MANAGE. 47(1):59-66 Marten were once indigenous to many of the wooded areas of the midwest. Their disappearance from these areas was apparently related to excessive trapping, fires, and logging during the 1800's and 1900's, which drastically reduced marten range throughout North America (Schupbach 1977). The marten was extirpated from Wisconsin in 1925 (Jackson 1961) and is currently classified as endangered in that state. The regrowth of forests in northern Wisconsin and upper Michigan in the last 50 years has created habitat that can again support marten. An attempt to introduce marten during 1969-70 in upper Michigan failed because of trapping pressure and emigration (Schupbach 1977). The U.S. Forest Service and the Wisconsin Department of Natural Resources (WDNR) released marten into the northwest portion of the Nicolet National Forest in 1975-76. Concurrent with the release, a study was initiated to evaluate: (1) effects of 2 release methods, (2) marten movements after release, and (3) marten reproduction. Research was conducted from I January 1975 to 30 June 1976. I thank L. Martoglio, E. Nelson, R. Perre-Davis, J. Toepfer, P. Vanderschaegen, and especially R. K. Anderson for support throughout the project. The U.S. Forest Service (Region 9), Wisconsin Department of Natural Resources, and University of Wisconsin-Stevens Point provided financial support. STUDY AREA AND METHODS Marten were released into the Fisher Management Unit (FMU) in the Nicolet National Forest (Fig. 1). This 560-km2 area consists mainly of large lowlands and dense hardwoods within the Pine River Watershed, Forest County. It has been closed to dry-set trapping since the 1960's when fisher (Martes pennanti) were successfully reintroduced. The average annual p ecipitation in the area is 76.2 cm and the average snowfall is 127.0-152.4 cm. J n ry temperatures average -10.8 C, July temperatures average 18.7 C, and annual temperatures average 4.3 C. The FMU contains a variety of habitats differing in composition, age, and size. Large homogeneous stands are not characteristic of this area. Parallel northeastIPresent address: Bureau of Land Management, Battle Mountain, NV 89820. J. Wildl. Manage. 47(1):1983 59 This content downloaded from 207.46.13.120 on Wed, 14 Sep 2016 05:38:20 UTC All use subject to http://about.jstor.org/terms 60 MOVEMENTS OF INTRODUCED MARTEN * Davis

Diets of Domestic Sheep and Other Large Herbivores in Southcentral Colorado

Diets of Domestic Sheep and Other Large Herbivores in Southcentral Colorado

Lichen Biomass in Acadian and Boreal Forests of Cape Breton Island, Nova Scotia

Lichen Biomass in Acadian and Boreal Forests of Cape Breton Island, Nova Scotia

Snowmelt delay by oversnow travel

Oversnow vehicles compact the snowpack several inches as a result of their passage; drifting snow tends to refill these tracks to ambient level. This repeated travel and drifting result in storage of much greater water content in the snowmobile trails than in the adjacent undisturbed snowpack. A brief field study was initiated to determine the magnitude of the increase in water content and the time delay of snowmelt in an area frequently traveled by oversnow vehicles.The area chosen for study was an abandoned farm with an elevation of 700–1100 feet msl near the confluence of the Schoharie and Mohawk valleys. The area is quite hilly, and the rather steep slopes face north or east. Average snowfall in this area is about 80 in./year. During the study year approximately 120 inches fell, and there was continuous total snow cover from December 4, 1970, until the first bare spots appeared on April 1, 1971. Snowmobile travel began with the first snow and continued through the winter, the last known passage occurring after the snowstorm of April 10. No accurate log of time or number of snow vehicle traverses was maintained; however, 25–50 passages per week would be a reasonable estimate of traffic over the most often used trail.

Snowfall in Maine

S NOWFALL studies have been made covering New England as a whole,' but none have been made of Maine in any detail. It is the purpose of this paper to present such a study for that state.2 The series of maps shows average snowfall as based primarily on the records from I895 to I935 for eight stations; these stations have been supplemented by 20 stations with shorter records (down to 6 years). The shorterterm stations have been reduced to the i895-I935 period, when possible, with stations of a longer record in the same locality. In drawing the isometric lines between stations, altitude has been taken into consideration.

Chart XI. Average Annual Snowfall.

Chart XI. Average Annual Snowfall.