Winter Thaw Research Articles

Thaw effects on cold-hardiness parameters in yellow birch

One-year-old, cold-hardened, container-grown yellow birch (Betula alleghaniensis Britt.) seedlings were exposed to cold treatments after being pretreated with a simulated winter thaw. Freezing injury to roots and shoots was assessed by relative electrolyte leakage and triphenyltetrazolium chloride reduction. Growth characteristics were also determined after 60 days under greenhouse conditions. Relative electrolyte leakage and triphenyltetrazolium chloride reduction measurements showed that roots became increasingly damaged with decreasing cold-treatment temperatures. However, plants pretreated with thaws showed significantly lower stem increment, shoot length, and leaf area in response to the cold temperatures than did the unthawed plants. Variation in these growth parameters was also significantly correlated with both root and shoot freezing injury parameters. Cold hardiness under different thaw pretreatments was assessed using the highest freezing temperature that caused significant injury, referred to as the critical temperature. For seedlings without the thaw pretreatment, shoot and root critical temperatures were estimated as –52.5 and 23.8°C, respectively. Following 12 days of thaw, these temperatures increased to –24.08°C for shoots and –13°C for roots. Twelve days of thaw, or growing degree-day (>4°C) accumulations greater than 66 during a thaw, could sufficiently deharden roots and shoots such that they would be susceptible to freezing damage at ambient temperatures commonly encountered in the Canadian Maritimes. We also observed that root pressure declined significantly with increasing root freezing injury. Sufficient root pressure is required for springtime refilling of xylem embolisms caused by winter cavitation of the vessels in this species. Weak root pressure caused by freezing injury would represent a risk of shoot dieback and tree decline due to the remaining embolisms reducing water flow to the developing foliage. The rapid reduction of shoot cold hardiness may also indicate the threat of late-spring frosts to this species. These induced changes are especially important under climate change scenarios that suggest increases in winter temperatures and changes in seasonality in eastern Canada.Key words: climate change, cold hardiness, electrolyte leakage, growth, root pressure, TTC reduction.

Photosynthesis of overwintering evergreen plants.

In this review we focus on photosynthetic behavior of overwintering evergreens with an emphasis on both the acclimative responses of photosynthesis to cold and the winter behavior of photosynthesis in conifers. Photosynthetic acclimation is discussed in terms of the requirement for a balance between the energy absorbed through largely temperature-insensitive photochemical processes and the energy used for temperature-sensitive biochemical processes and growth. Cold acclimation transforms the xanthophyll-mediated nonphotochemical antenna quenching of absorbed light from a short-term dynamic response to a long-term sustained quenching for the whole winter period. This acclimative response helps protect the evergreen foliage from photooxidative damage during the winter when photosynthesis is restricted or prevented by low temperatures. Although the molecular mechanisms behind the sustained winter excitation quenching are largely unknown, it does involve major alterations in the organization and composition of the photosystem II antenna. In addition, photosystem I may play an important role in overwintering evergreens not only by quenching absorbed light photochemically via its support of cyclic electron transport at low temperatures, but also by nonphotochemical quenching of absorbed light irrespective of temperature. The possible role of photosystem II reaction centers in nonphotochemical quenching of absorbed energy in overwintering evergreens is also discussed. Processes like chlororespiration and cyclic electron transport may also be important for maintaining the functional integrity of the photosynthetic apparatus of overwintering evergreens both during periods of thawing in winter and during recovery from winter stress in spring. We suggest that the photosynthetic acclimation responses of overwintering evergreens represent specific evolutionary adaptations for plant species that invest in the long-term maintenance of leaf structure in cold climatic zones as exemplified by the boreal forests of the Northern Hemisphere.

Responses of xylem cavitation, freezing injury and shoot dieback to a simulated winter thaw in yellow birch seedlings growing in different nursery culture regimes

Seedlings of yellow birch originating from the same seed source were treated with two levels of fertilizers during two growing seasons. The lower level of fertilizers, such as 50 (11:41:08 N:P:K ratio), 100 (20:08:20) and 35 ppm of nitrogen (08:20:30) were applied as the starter, grower and finisher, respectively. The higher level ones consisted of 75, 150, and 100 ppm of nitrogen in the same fertilizers. After 2 years growth, seedlings treated with the higher level of fertilizers, had fewer lateral branches, greater height and larger stem diameter. After natural hardening from November to February, seedlings were subjected to 0, 5, 10, 19 and 27 days of a simulated winter thaw followed by 10 weeks at −10°C. After the thaw-refreeze treatments, series of measurements were carried out. Stem xylem cavitation and root freezing injury significantly increased with thaw duration regardless of levels of fertilizer treatments. Stem freezing injury also significantly increased with thaw duration in all stem segments of seedlings treated with the higher level of fertilizers, but only in the top segments for the seedlings provided with the lower level of fertilizers. However, seedlings treated with the higher level of fertilizers developed cavitation more quickly. After 1 month of growth in the greenhouse following the thaw and freeze treatment, both types of seedlings showed significant decrease in the length of new shoot growth and increase in percent length of shoot dieback with thaw duration. The length of new shoots, however, was always greater for the plants treated with the higher level of fertilizers. No difference of shoot dieback between the seedlings of the two different nursery treatments were observed. Correlation analyses showed that the length of new shoots was highly related to root and stem freezing injury, while dieback was best correlated with root freezing injury and stem xylem cavitation regardless of the levels of fertilizer treatments. It was concluded that (1) the higher level of fertilizer applied during the culture of yellow birch seedlings can accelerate xylem cavitation and dehardening in the stem following freeze–thaw events; (2) stem xylem cavitation was unlikely the cause of stem freezing injury; and (3) root freezing injury and stem xylem cavitation are the most reliable measurements for predicting dieback of potential planting stock, but both root and shoot freezing injury are relate well to regrowth of new shoots in stock exposed to prolonged thaw.

Winter and Spring Thaw Measurements of N2O, NO and NOx Fluxes using a Micrometeorological Method

The impact of nitrogen fertilizers on gaseous emissions duringwinter and spring-thaw is not well understood and was the objective of this research. Using a micrometeorological method,N2O, NO and NOx fluxes from ryegrass were measured from November 1997 to March 1998. Three different mineralfertilizers were applied in November: urea (U), slow-release urea(SRU) and ammonium nitrate (AN). N2O emissions during the winter were small, increasing significantly in March. Total losses of N2O-N were significantly higher from SRU and U plots, with winter N2O emissions accounting for ∼50% of annual losses. Nitric oxide fluxes from all plots weresmall during the measurement period (<0.9 ng N m-2 s-1). The NO fluxes from U and AN fertilized plots were significantly higher than from SRU and control plots. NO2 fluxes were always negative (∼–6 ng N m-2 s-1)indicating deposition, but decreased to ∼–2 ng N m-2s-1 when snow was present on the soil surface. Our resultsindicate that the form of inorganic N applied has an effect on NO+ N2O emissions but not on NO2 fluxes.

Winter Photosynthesis in Red Spruce (Picea rubens Sarg.): Limitations, Potential Benefits, and Risks

Numerous cold-induced changes in physiology limit the capacity of northern conifers to photosynthesize during winter. Studies of red spruce (Picea rubens Sarg.) have shown that rates of field photosynthesis (Pfield) and laboratory measurements of photosynthetic capacity (Pmax) generally parallel seasonal ambient temperature trends; carbon exchange decreases in the fall, remains negative or close to zero for much of the winter, and increases in the spring. However, increases in Pfield, Pmax, and foliar carbohydrate concentrations can occur during winter thaws. Thaw-induced increases in photosynthesis are probably not the result of increased stomatal conductance, but may result from other changes in physiology associated with thaw-induced improvements in water relations. In addition to increased photosynthesis, red spruce also decrease in cold hardiness during thaws. The cooccurrence of thaw-induced changes in photosynthesis and cold hardiness raises questions regarding their adaptive significance, particularly in the context of potential climate change. Red spruce may face a tradeoff between potentially beneficial increases in carbon capture and potentially detrimental reductions in cold tolerance. The physiological consequence(s) of this tradeoff may depend on the number and duration of thaws, as well as ambient temperature trends following thaw. Pollution-induced reductions in cold tolerance, and the low genetic variability of red spruce, may also influence the net outcome of thaw-induced changes in physiology.

Winter Photosynthesis in Red Spruce (Picea rubens Sarg.): Limitations, Potential Benefits, and Risks

Numerous cold-induced changes in physiology limit the capacity of northern conifers to photosynthesize during winter. Studies of red spruce (Picea rubens Sarg.) have shown that rates of field photosynthesis (Pfield) and laboratory measurements of photosynthetic capacity (Pmax) generally parallel seasonal ambient temperature trends; carbon exchange decreases in the fall, remains negative or close to zero for much of the winter, and increases in the spring. However, increases in Pfield, Pmax, and foliar carbohydrate concentrations can occur during winter thaws. Thaw-induced increases in photosynthesis are probably not the result of increased stomatal conductance, but may result from other changes in physiology associated with thaw-induced improvements in water relations. In addition to increased photosynthesis, red spruce also decrease in cold hardiness during thaws. The cooccurrence of thaw-induced changes in photosynthesis and cold hardiness raises questions regarding their adaptive significance, particularly in the context of potential climate change. Red spruce may face a tradeoff between potentially beneficial increases in carbon capture and potentially detrimental reductions in cold tolerance. The physiological consequence(s) of this tradeoff may depend on the number and duration of thaws, as well as ambient temperature trends following thaw. Pollution-induced reductions in cold tolerance, and the low genetic variability of red spruce, may also influence the net outcome of thaw-induced changes in physiology.

Effects of xylem cavitation and freezing injury on dieback of yellow birch (Betula alleghaniensis) in relation to a simulated winter thaw.

Shoot dieback, shoot growth, stem xylem cavitation, stem and root freezing injury, and root pressure were measured in 2-year-old, cold-hardened, potted yellow birch (Betula alleghaniensis Britt.) seedlings that had been subjected to a simulated winter thaw for 0, 5, 10, 19 or 27 days followed by 10 weeks at -10 degrees C. Stem xylem cavitation was determined as percent loss of hydraulic conductivity. Stem freezing injury was measured as electrolyte leakage (EL). Root freezing injury was determined by EL and by triphenyl tetrazolium chloride (TTC) reduction. Thaw duration was significantly correlated with dieback, new shoot growth, stem xylem cavitation, stem and root freezing damage, and root pressure (P < 0.05). In particular, shoot dieback was positively correlated with stem xylem cavitation (P < 0.001), residual stem xylem cavitation (P < 0.01) and root freezing injury (P < 0.010), but only weakly correlated with stem freezing damage (P < 0.05). In roots, freezing damage was negatively correlated with root pressure (P < 0.05), which, in turn, was negatively correlated with residual stem xylem cavitation after root pressure development. In stems, there was no correlation between freezing damage and xylem cavitation. We conclude that long periods of winter thaw followed by freezing resulted in freezing injury to roots concomitant with a reduction in root pressures, leading to poor recovery from freezing-induced xylem embolism.

Effects of duration of a simulated winter thaw on dieback and xylem conductivity of Betula papyrifera.

Stems or roots + stems of potted, 2-year-old paper birch (Betula papyrifera L.) were subjected to simulated winter thaws of various durations in climate-controlled chambers. The simulated thaws induced dieback of shoots of the treated plants. Although the stem thaw treatment did not significantly increase dieback, there were significant (P < 0.05) correlations between growing degree days above 4 degrees C and both shoot dieback and percent reduction in conductive xylem. All trees that received > 60 growing degree days (GDD) > 4 degrees C died back to some extent. Plants in the root + stem thaw treatment that received more than 60 GDD > 4 degrees C showed a significant (P < 0.05) increase in dieback and a significant (P < 0.05) loss of conducting xylem after a period of growth and recovery in the greenhouse, especially in the xylem of 1-year-old stems. Furthermore, higher correlations between GDD > 4 degrees C during a thaw and both the extent of dieback and the loss in conductive xylem were found in trees subjected to the root + stem thaw treatments than in trees exposed only to the stem thaw treatments (P < 0.05). The root + stem thaw treatments also resulted in highly significant relationships (P < 0.05-0.001) between loss in conductive xylem and dieback. The occurrence of dieback in response to winter thaws, and its close correlation with irreversible losses of xylem conductivity due to embolisms, coupled with an inability to refill the xylem because of root damage, support the view that these processes may be key factors in initiating birch decline.

Physiological changes in red spruce seedlings during a simulated winter thaw.

We evaluated net photosynthesis, respiration, leaf conductance, xylem pressure potential (XPP) and cold hardiness in red spruce (Picea rubens Sarg.) seedlings exposed to either a continuous thaw (CT) or a daytime thaw with freezing nights (FN) for 8 days during mid-winter. Physiological differences between CT and FN seedlings were evident for all measured parameters. However, the temporal expression of treatment differences varied among parameters. When compared to FN seedlings, CT seedlings had higher rates of respiration following 24 h of treatment, and a higher net photosynthetic rate, leaf conductance and XPP after 48 h of treatment. The CT seedlings were significantly less cold tolerant than the FN seedlings following 4 days of thaw, whereas FN seedlings did not deharden over the 8 days of treatment. Examination of temporal trends among thaw-associated changes in physiology suggested that, although greater carbon exchange occurred as stomatal conductance increased, the transition from negative to positive net photosynthesis was not the result of increases in conductance, but may have been associated with thaw-induced increases in XPP. Because thaw-associated changes in gas exchange and cold hardiness were offset in time, we conclude that, if changes in these processes are physiologically linked, the linkage is indirect.

Agroclimatic Hazards and Dairy Farming in Wisconsin

Agroclimatic Hazards and Dairy Farming in Wisconsin

Dormant Pruning Rehardening of Peach Pistils after a Winter Thaw

Dormant Pruning Rehardening of Peach Pistils after a Winter Thaw

Effects of acid deposition on watershed ecosystems of national parks in the great lakes basin

Legally protected national parks provide an appropriate substrate for essential long-term study of ecosystem structure and function, and for detecting trends in natural and human-induced stress. The absence of unplanned site manipulation in such areas is especially valuable for such research. Our present research has two major components. The first is the long-term ecosystem-level study of the effects of atmospheric contaminants on ecosystem processes. The overall objective is to evaluate ecosystem aquatic/terrestrial linkages and their role in establishing aquatic ecosystem sensitivity to anthropic atmospheric inputs. Four watershed/lake ecosystems, representative of much of the region's diversity, are under study. Two mature boreal sites on Isle Royale are characterized by first-order perennial surface stream input and lake outflow. Two additional mainland northern hardwood sites, one with shallow soils and one with soils derived from glacial till, are characterized by sensitive aquatic systems. One site is in a private reserve and the other in Pictured Rocks National Lakeshore. Surface outflow is gaged by Parshall flume and stage height recorder. Meteorological stations record variables for estimating evapotranspiration. One-tenth ha plots have been established in all watersheds and three sites have had intensive study of precipitation modification by canopy and forest soil. Five-year mean maximum and minimum lake pH varies from 6.85 to 4.94, Ca(2+) from 1070 to 54 μ eq l(-1), K(+) from 5.42 to 8.35 μ eq l(-1), NH 4 (+) from 10.12 to 3.23 μ eq l(-1), HCO 3 (sup-) from 635 to 24 μ eq l(-1), NO 3 (sup-) from 3.27 to 1.54 μ eq l(-1), and SO 4 (sup2-) from 110 to 52.7 μ eq l(-1). The relatively high NO 3 (sup-) values observed in one lake are the result of stream drainage from a watershed dominated by Alnus rugosa, and another has high seasonal NO 3 (sup-) inputs during spring runoff. However, owing to periodic winter thaws, significant snowpack release of nutrients generally precedes maximum spring stream runoff. Water chemistry in both sensitive and non-sensitive lakes appears to be primarily reflecting how the conterminous terrestrial system is retaining atmospheric inputs more than the quality of direct lake atmospheric input. This is especially evident for H(+), NO 3 (sup-) and SO 4 (sup2-) .The second component is the assessment of watershed acidification, SO 4 (sup2-) output and soil retention across an input gradient. An anthropic deposition gradient provides the opportunity for intersite time-trend analyses as to the effects of inputs. Our study objective was to see if the decreasing west to east input/output values for SO 4 (sup2-) , noted in small first-order watersheds in national parks from Minnesota to Ohio, might be related to present atmospheric inputs, potential and total soil SO 4 (sup2-) adsorption, or soil SO 4 (sup2-) desorption from earlier higher inputs. Precipitation pH ranged from 5.05 at Fernberg, Minnesota to 4.24 at Wooster, Ohio. Minimum and maximum concentrations of NH 4 (+) , NO 3 (sup-) , SO 4 (sup2-) and Cl(-) were also found at these stations. Stream water concentrations of NO 3 (sup-) and SO 4 (sup2-) increase in a similar but sharper gradient. Streams are well buffered. Cation, HCO 3 (sup-) , NO 3 (sup-) and especially SO 4 (sup2-) output increase west to east, but H(+) output decreases. At the eastern site stream SO 4 (sup2-) concentration and output exceed HCO 3 (sup-) . Potential soil SO 4 (sup2-) adsorption capacity increases eastward, but this capacity is filled. Crystalline Fe hydrous oxides appear more effective than amorphous Fe hydrous oxides at adsorbing SO 4 (sup2-) . High anthropic anion inputs, inability of forest soil to adsorb additional inputs and perhaps SO 4 (sup2-) desorption appear responsible for the replacement of HCO 3 (sup-) by SO 4 (sup2-) in stream water. The major cation accompanying SO 4 (sup2-) is Ca(2+).

The pattern of winter respiratory response to temperature, moisture, and freeze–thaw exposure in Bouteloua gracilis dominated grassland soils of southwestern Alberta

Winter respiratory activity of soils from Bouteloua gracilis dominated grassland of southwestern Alberta was examined, both under in situ field conditions and over a matrix of defined laboratory conditions. The effect of winter thaw conditions was very pronounced on observed rates of soil surface CO2 evolution. Under conditions of diurnally fluctuating air temperatures, from ca. −18 to +8 °C, soil surface temperatures in early January ranged from ca. −12 to +4 °C, while concurrently measured respiratory activity ranged from less than 2 to over 16 mg CO2∙m−2∙h−1. By early spring, soil surface heating was even more extreme as a result of the greater magnitude of midday insolation exposure, with observed mean values of CO2 release ranging from less than 10 to over 60 mg CO2∙m−2∙h−1. Laboratory incubations showed continued, although low rates of respiratory activity in soils held at subzero temperatures, with a marked biphasic response pattern evident in Arrhenius plots of soil respiration. Predicted cumulative soil surface CO2 release was estimated at 34–48 g CO2∙m−2, depending on whether the effects of observed postthaw respiratory response were included. Some 55% of overall winter soil respiratory activity in the top 8 cm of the soil profile is predicted to occur at temperatures between −4 and +4 °C, with the remaining respiratory activity largely occurring at temperatures up to 15 °C. This magnitude of soil surface CO2 release represents between 3 and 30% of previously observed estimates of belowground root mass loss in the winter period, depending on whether this mass loss is presumed to occur over the entire winter period or mainly in early spring, coinciding with the peak period of root exudate production.

Soil Losses from Roadbeds and Cut and Fill Slopes in the Southern Appalachian Mountains

Abstract Soil losses were measured on the cut, fill, and roadbed surfaces of a forest road at Coweeta Hydrologic Laboratory. Before grass was planted or gravel spread, roadbed surfaces had the least loss per unit area and loss was primarily waterborne fine particles. A large part of the soil loss from fill slopes was due to slippage of wet soils in early spring. Surface erosion of fills was negligible because storm water from the roadbed was not spilled across loose soil. The cut slopes eroded most, principally because soils were loosened by diurnal cycles of freezing and thawing in winter. This study shows that inclined surfaces of cut and fill slopes are potential sources of large soil loss but these losses can be mitigated by early establishment of grass cover and by design features to control storm water. Soil loss from roadbeds was greatly reduced by gravel surfacing.¹

The Northern Muddy Intertidal: Seasonal Factors Controlling Erosion and Deposition — A Review

This review summarizes the seasonal physical and biological processes which take place on and in the muddy intertidal zone during the year and affect the erosion or deposition of sediment. The main physical processes that are considered are the effects of ice, waves, sediment dewatering, rain, and mud and water temperatures. The biological processes include the growth of benthic diatoms, algal mats, and higher plants as well as the effects of bioturbation, pellet formation, biodeposition, and changes in the intertidal microrelief.In the early spring in northern temperate estuaries, ice break-up is the most significant factor affecting muddy intertidal sedimentation. The ice-roughened intertidal has not yet been affected significantly by either plant or animal activity, and is particularly susceptible to sediment resuspension by waves. During the summer, organic processes dominate the intertidal as organisms feed on, pelletize, and bioturbate the sediments. Plant growth, especially benthic diatoms and algal mats, may stabilize the sediment. The few storms during this season combined with lower rainfall insure that the muddy intertidal only rarely undergoes erosion. In fall, seasonal storms increase while both plant and animal activity begin to slow down. Lower rates of bioturbation make the muddy intertidal more resistant to erosion, but the intensity of the fall storms, and higher rainfall, cause significant sediment scouring. With the onset of winter, ice forms over and on the muddy intertidal, reducing resuspension and erosion. However, significant sediment erosion and transportation occurs during winter thaws, when temporary ice break up occurs. But the effect of ice "armoring" all but eliminates sediment resuspension by waves over the muddy intertidal for most of the coldest winter months.Key words: intertidal zone, erosion, deposition

Measurement of soil water contents and frozen soil depth during a thaw using time‐domain reflectometry

Abstract The results of a field test of time‐domain reflectometry (TDR) to measure apparent liquid soil water contents and to locate the unfrozen‐frozen interface during thawing conditions is presented. The apparent liquid water content was observed in the fall and through a late winter thaw on two sand sites, one with a natural snow cover and the other with snow removed throughout the winter. Temperatures were monitored at intervals throughout the profile. The results indicate that TDR provides a method for monitoring apparent liquid water content andfreeze‐thaw processes.

The Silence Between Seasons

The Silence Between Seasons Seasons — our way of squaring natural circles, of building a four-cornered house for time. But we live between these angles, beside the four connecting walls. When winter thaws, the landscape flattens, open but bare. Like hope without sustenance, leafless trees bear blossoms. We trust, like burried seed, that cold won't come again. We lie in sun, on edges of pools whose waters hold winter. We warm, but the skin ripples under the wind like the mind under its memories. Then cloudburst. Late summer laps up water like a dog. Dust swirls. Leaves crackle under heat, but cling to limbs as if expecting spring. We know better. But passion burnt, we won't let go. What there was is harvested and stored. What's left is dead but not yet buried. It rattles life by day. But night comes, and frost, and what blew free is coffined by ice to the earth. BETTY FLOWERS ...

Factors involved in overwintering survival of the freeze tolerant beetle,Dendroides canadensis

Overwintering larvae of the beetle,Dendroides canadensis, from northern Indiana were able to survice freezing at temperatures down to −28°C. During a late winter thaw or upon warm acclimation the larvae became freeze susceptible, but cold acclimation or acclimatization restored freeze tolerance. Concentrations of the cryoprotectants glycerol and sorbitol, ice nucleating agents (probably proteins) and thermal hysteresis proteins increase in the autumn, peak in winter and decline in spring. These and other, as yet unknown, factors are responsible for the capacity ofDendroides to survice subzero temperatures. The hemolymph ice nucleating agents limit the amount of undercooling to approximately 1°C below the hemolymph freezing point and thereby prevent lethal intracellular ice formation. Therefore, the freezing point depression provided by the thermal hysteresis proteins becomes essential to the survival of the larvae during periods such as winter thaws, autumn, and spring when the larvae are freeze susceptible.

ROAD DE‐ICING SALTS IN AN URBAN STREAM AND FLOOD CONTROL RESERVOIR1

ABSTRACT: High concentrations of chloride and sodium were found in the bottom layers of a new flood control reservoir at the beginning of winter thaw periods. The reservoir had a number of significant downstream impacts. After short thaw periods, discharge from the bottom of the reservoir tended to cause higher salt concentrations downstream in comparison with upstream sites. During long thaw periods or when large quantities of rain fell, downstream salt concentrations were considerably less than upstream values. Average chloride and sodium content of soil at the bottom of the reservoir more than doubled as a result of impounding runoff waters for one winter.

A COMPARISON OF PHOSPHORUS AND WATER CONTRIBUTIONS BY SNOWFALL AND RAIN IN NORTHEAST OHIO1

ABSTRACT A record snowfall of 55.8 centimeters occurred on December 1 and 2, 1974 in Portage County, Ohio. An early winter thaw melted the greater part of the snow by December 22, 1974, and a two‐day rain fell from December 23 to December 25. These weather events provided an opportunity to compare snowmelt and rainfall contribution to runoff and phosphorus loading to the Twin Lakes Watershed. Phosphorus concentrations of the snow and rain were determined. Six lake inflows and two lake outflows were measured daily for volume and phosphorus concentration.The snow added 217,000 cubic meters of water and 2.2 kilograms of total phosphorus to the watershed. The rain added 74,000 cubic meters of water and 1.6 kilograms of total phosphorus. Total water discharge from the watershed during December was 244,537 cubic meters and total phosphorus output was 20.3 kilograms. The snow provided 49.9% of the discharge and 8% of the phosphorus whereas the rainfall contributed 28% of the discharge and 6% of the phosphorus. These results indicate that while snow is a significant source of water, it is not a large source of phosphorus. The greatest contribution of phosphorus comes from fine sediment carried by storm runoff.