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APA3385
SUSITNA HYDROELECTRIC P R OJECT FEDERAL ENERGY REGULATORY COMMISSION PROJECT No. 7114 MARCH 1985 SNOW DEPTH SURVEY IN THE MIDDLE SUSITNA RIVER BASIN, ALASKA PREPARED BY Aloollo ltooooroll Aoooolotoo UNDER CONTRACT TO [}{]~[¥3~~=~®~®00 SUSITNA JOINT V~N T'URE FINAL REPORT JANUARY 1988 DOCUMENT No. 3385 Alaska Power Authority ======::::J r r '- l l SUSITNA HYDROELECTRIC PROJECT MARCH 1985 SNOW DEPTH SURVEY IN THE MIDDLE SUSITNA RIVER BASIN, ALASKA Report by LGL Alaska Research Associates, Inc. Willie~ D. Steigers, Jr., LGL Warren B. Ballard, AIF &G Ear 1 f. Becker, AIF &G Under contract to Harza-Ebasco Susitna Joint Venture Prepared for Alaska Power Authority Final Report Janua ry 1986 Docu•nt No . JJ85 S uaitre f ile No . 4.3.3.2 NOTICE ANY QUESTIONS OR COMMENTS CONCERNING THIS REPORT SHOULD BE DIRECTED TO THE ALASKA POWER AUTHORITY SUSITNA PROJECT OFFICE 11 LIST OF ffiURES v i 1 NTRD..Cl"DJ 1 2 ~ 2 3 STI.OYft.FEA 2 4 ~ 3 4.1 Snow Survey 3 4.2 Winter Bird Transects 4 5 FES..l.lS 5 5.1 Snow Site Descriptions 5 Snow Site 1 5 Snow Sije 1 !Bl 6 Snow Site 1 !El 6 Snow Sjte 1 !W) 6 Summary of Snow Site 1 6 SnowSije2 7 Snow Sije3 7 SnowSije4 7 Snow SiteS 8 Snow Sije6 8 Sr,owSije7 9 Snow Sije8 9 SnowSije9 10 Snow Site 10 10 Snow Sije 11 11 Snow Sije 12 11 i ii Bg Snow Site 13 11 Snow Site 14 12 Snow Site 15 12 Snow Sije 16 13 SnowSije 17 13 Snow Sjte 1J 13 Snow Sije 19 14 Snow Sije2Q 14 Snow Stte 21 14 Snow Sjte 22 15 SnowSije23 15 SnowSije24 16 Snow Stte 25 16 Snow Sije 26 17 Snow Sije 27 17 Snow Sije 28 18 ~owSije29 18 Snow Sije 30 18 Snow Sije 31 19 5.2 Winter Bird Transect Site Descriptions 19 Bird Transect 1 19 Bird Transect 2 19 Bird Transect 3 20 Bjrd Transect 4 20 Bird Transect 5 21 Bird Transect 6 21 5 .3 Comparisons Among Sttes 22 lV 6 '7 8 v ~ 23 24 25 UST OF FlGU:U:S Figure 1 March 1985 snow depth survey sites in the middle Susitna bas in, Alaska 27 2 Snow depths at sequential sample points for snow site 1 (B). 28 3 Snow depths at sequential sample points for snow site 1 (E). 29 4 Snow depths at sequential sample points for snow site 1 C'N). 30 5 Snow depths at sequential sample points for snow site 2. 3 1 6 Snow depths at sequential sample points for snow site 3. 32 7 Snow depths at sequential sample points for snow site 4. 33 8 Snow depths at sequential sample points for snow site 5. 34 9 Snow depths at sequential sample points for snow site 6. 35 10 Snow depths at sequential sample points for snow site 7. 36 11 Snow depths at sequential sample points for snow site 8. 37 12 Snow depths at sequential sample points for snow site 9. 38 13 Snow depths at sequential sample points for snow site 1 0. 39 14 Snow depths at sequential sample points for snow site 11. 40 15 Snow depths at sequential sample points for snow site 12. 41 ~ 16 Snow depths at sequential sample points for snow site 13. 42 17 Snow depths at sequential sample points for snow site 14. 43 18 Snow depths at sequential sample points for snow site 15. 44 19 Snow depths at sequential sample points for snow site 16. 45 20 Snow depths at sequential sample points for snow site 17. 46 21 Snow depths at sequential sample points for snow site 18. 47 22 Snow depths at sequential sample points for snow site 19. 48 23 Snow depths at sequential sample points for snow site 20. 49 24 Snow depths at sequential sample points for snow site 21. 50 Vl Figure fa 25 Snow depths at sequential sample points for snow site 22 . 51 26 Snow depths at sequential sample points for snow site 23 . 52 27 Snow depths at sequential samp le points for snow site 24 . 53 2 8 Snow depths at sequential sample points for snow site 25. 54 29 Snow depths at sequential sample points for snow site 26. 55 30 Snow depths at sequential sample points for snow site 26 . 56 3 1 Snow depths at sequentia~ s. pie points for snow site 28. 57 32 Snow depths at sequential sample points for snow site 29. 58 33 Snow depths at sequential sample points for snow site 30. 59 34 Snow depths at sequential sample points for snow site 31. 60 35 March 1985 snow depth bird transects in the middle Susitna River basin, Alaska. 61 36 Snow depths at sequential 15 minute intervals for bird transect 1. 62 3 7 Snow depths at sequential 15 minute intervals for bird transect 2. 63 38 Snow depths at sequential 15 minute intervals for bird transect 3. 64 39 Snow depths at sequential 15 minute intervals for bird transect 4. 65 40 Snow depths at sequential 15 minute intervals for bird transect 5. 66 41 Snow depths at sequential 15 minute intervals for bird transect 6. 67 42 Comparison of snow depths for sites in the Jay Creek drainage. 68 vii Figure 43 Comparison of snow depths for sites in the Coal Creek drainage. 69 44 Comparison of sncm depths for sites in the Watana Creek drainage. 70 45 Comparison of snow depths for sites in the Clark/T susena Creek drainage. 71 4 6 Comparison of snow depths for sites in the Devil Creek drainage. 72 47 Comparison of snow depths and decreasing elevations for 31 snow sites. 73 viii ~ Depth an d quality of snow in winter have the capacity to limit moos e (~ ~ ~populations in Alaska. Snow depth, density, crust layers in the snow profile, and duration of the snowpack are probably the most important characteristics (Coady 197 4 , Kelsall and Telfer 1974). Deep, dense, and/or hard-packed snow increases energy requ ired for locomotion to obtain food , and covers the food making it less access ible to forag ing moose (Coady 1974, LeResc.1e 1974). Studies have shown that moose can travel more or le ss freely through soft snow up to about 24 inches deep (Telfer 1970), but are increas ingly restricted in their movements as snow becomes crusted, denser, harder, or as depths of soft snow increase beyond 24 inches. Moose are generally absent from areas in North America where snow depths greater than 28 inches persist for more than about 2 months each winter (Kelsall and Telfer 1974). Construction of the Susitna Hydroelectric Project in the middle Susitna River basin of southcentral Alas ka would make lower elevation habitats within the 2 impoundment zones unavailable to wintering moose. In the project area upstream of the Devil Canyon dams ite moose generally occupy lower elevations (1 ,800-3,000 ft) from mid-winter through early spring (January-May) and then, in the post-calving period , move to higher elevations (< 4,000 ft) where they remain through the rutting period in fall (Septem ber- October) (Ballard et al. 1983}. Many moose again decend to lower elevations at some time during the mid-winter to early spri n g period. As snow accumulates during the winter, many moose make their way to lower elevation habitats. They tend to remain there until ameliorating snow and weather conditions permit them to leave. Initiation of these movements often appears to be associated with recent increases in local snow accumulation . For moose whose range of movements overlap the project imJX>undments zones, movement to lower elevations can take them below the high pool levels. Snow in the project area usually reaches its greatest cummulative depth near the end of March and generally begins reced ing thereafter. Although snow depths vary greatl y 2 throughout the middle basin, they are known to increase from east to we t. Histc ~i cal snow survey records in this area of 20 inches near the Oshetna River (Square Lake}, 23 inches at Fog Lakes near the Watana dam sit , and 33 inches near Devil Canyon (SCS 1985} show that average snow depth increases from east to west. Snow depths are generally assumed to increase from lower to higher elevations. However, no reliable information was available for snow depths over elevational gradients within the project area, particularly with i n major tributary drainages. Movement tterns of most radio-collared moose inve!itigated from 1976 through 1983 appeared to be related to the drainc.. .... J patterns of Sus itna River tributaries (Ballard e.t al. 1982, 1983, 1984}. As a result, most movements in the middle basin approximate a ger.dral north-south pattern. The objective of this snow survey study was to obtain preliminary data on snow depths by elevation along major tributaries of the Susitna River in the m iddle basin. 2~ A number of individuals contributed ideas for this preliminary study . They include Jack Whitman, C raig Gardner, and Karl Schneider (Alaska Department of Fish and Game}, Randy Fairbanks (Harza-Ebasco Susitna Joint Venture}, and Robin Sener (LGL Alaska Research Associates, Inc}. We also thank Dale Herter and Br ian Cooper of (LGL Alaska Research Associates, Inc} for collecting snow depth data during their winter bird transects . Rgures were prepared by Graphic Definitions and computer-generated. 3 sn.DY /JF£A The study area was located in the middle Susitna River basin in southcentral Alaska. The basin is generally oriented in an east-west direction between the Alaska Range to the north and the Talkeetna Mountains to the south. The basin is a broad U-shaped valley which has been dissected by the Susitna River, forming a relatively narrow V-shaped channel through the basin. Numerous stream and river tributaries enter the Susitna River along its course through the middle Basin. Elevations under study ranged from about 1 , 1 00 ft at the confluence of Devil Creek and the Susitna River to 3,600 ft near the headwaters of Coal 3 Creek. The w ide range of environmental conditions in the basin has resulted in a com ple x mosaic pattern of plant communities . Plant commun ity composi t ion and phys iognomy have been st rongly influenced by fire history, topography , soil moisture, aspect , and brows ing by large herbivores. Precipitation in the area averages about 20 inches an d most falls during the frost-free period . 4 WE11-0:S Two separate late-winter snow surveys in the middle Sus itna River bas in were conducted simultaneously during March 27-30, 1985. Snow depth information w as collected at sites based on prior knowledge of presence or absence of wintering moose (Ballard et al. 1982, 1983, 1984} during March 29 and 30, 1985. Concurrent w ith a winter bird census during March 27-29, 1985, snow depth inf rmation was also recorded at points along transects. Sample methods varied by source, so each are d iscussed separately. 4. 1 Snow Survey During March 29 and 30, 1985, 31 sites were sampled for depth of accumulated snow. Site selection was based primarily on a priori knowledge of use or no n-use of a specific are a by wintering moose (Ballard et al. 1982, 1983 , ~ 984) and on a concurrent moose st ratificat ion survey (Ballard et al. ~ 985}. Site selection usually followed major t ributary drainages of the Susitna River , or elevational gradients of the Susitna River canyon. Specific site locations were selected from the helicopter . S ites were usu ally grouped in sets of at least 3 to correspond with number of observers available for data collection . One observer was placed at each site (except site 1) by helicopter. The observer then selected a non-random line of travel based on the local topography and drainage pattern if near a stream and began sampling snow depths at 5 step (approximately 15ft) intervals along the line transect. As many different vegetation types and other physical or topographical features were sam pled as possible in an effort to obtain representation of the 4 variation in snow depths within a site. Therefore, transect placem e nt and length within a site were left to the discretion of the individual observer. Often several shorter , disjointed transects were conducted in lieu of a single, longer transect when site-spec if ic requirements d ictated . As most sites were selected with in drainages, moderate and ste e p slopes were usually not sampled . Snow depths were measured t u the nearest inch using fiberglass rods marked at 3- inch intervals. Data was recorded on voice tape recorders or field data notebooks , and later transcribed to data c;oh eets. Notes of interest, su ch as surface snow hardness , crust layers in the snow profile, shrub species present , relat ive past and present browsing pres su re , plant condition, animal sign, type of vegetation, and a narration of topographical pos ition ing were also recorded at stops along transects. Elevation, aspect, and slope were recorded , and the site location marked on U.S.G.S. topographical maps and 1:60,000 scale co lor-infrared photographs. A minimum of 20 measurements were taken at each site ; the maximum number was governed only by allotted time before return of the helicopter. 4.2 W inter Bird Transects During the March 27-29, 1985 winter bird census (Herter 1985), snow depth information was collected at systematic points along 6 li ne transects. Transects varied from 2. 7-4.2 miles in length, and followed the form of triangles, 4-sided polygons , or 2 o r 3 sides of 4-sided polygons (Herter 1985). Transects were placed through relatively large stands of homogeneous vegetation near the Susitna River channel, with most of thei r length within the Devil Canyon (2 transects) and Watana (4 transects) impoundment zones (Herter 1985). Snow depths were sampled at 15 minute intervals (e.g., 0830, 0845 , 0900 , etc .) while the observer slowly walked along a previously flagged transect. Ten consecut ive measurements spaced 2 short paces (approximately 3 ft) apart were taken in the dire ct ion of travel along the transect. Snow depth was measured t o the nearest 0.39 inc h (1 em) using a wooden dowel marked in 0.39 inch (1 em) increments . Vegetation class ification 5 (Viereck et al. 1982} was recorded at ecotype edges along the length of the transect (Herter 1985}. 5 FEU..TS Snow depth data was collected in a non-random sample scheme , where s ites , placement of trans ects within sites, and number of points sampled a long transects were determined by the individual bserver. Topographical and environmental features such as slope, aspect, elevation, and vegetation classification that may have affected snow depths were not controlled for between sites nor Within sites. This made comparisons between sites tentative and subject to individual interpretation. General trends appeared evident (given the aforementioned interpretive caution}, however, especially when within-s i t l~ 1ariation was narrated by the observer taking the measurements. Snow depth data has been presented as a series of points along the 1 or more disjoined transects conducted at each site. Sample points were presented in the order they were taken , and disjoined transects combined into a single series of points. The vertical axis portraying snow depth was standardized in all figures to facilitate comparison of relative variation within and among sites. Average snow depth was depicted as a solid horizontal line . A narrative of sampling conditions and other observations were included in the site descriptions when recorded by the observer. 5. 1 Snow Site Descriptions Snow Sije 1 Site 1 was located in a tributary of Jay Creek near its headwaters appro ximate y 11 miles upstream from it, mouth (Figure 1 }. Site 1 was at 3,575 ft elevation with a northerly aspect and medium (15 degree) slope. Vegetation was an open shrub .;anopy of resin birch (Betula glandulosa) and willow(~. Most shrubs showed little eviaence of browsing. Feltleaf (s.a!.ix alaxensis) willow growing to 15 ft in height near the stream had been heavily browsed in the distant past, although it showed little sign of recent browsing . No fresh moose sign was observed. Three observers collected snow depth data t site 1 ; 6 results were presented separately by observer as subsites and then summarized as a single s ite. Snow Subsjte 1 (8).--Subsite 1 (B) was first oriented parallel to an ti up the tributary stream. It then turned uphill toward a northeast-facing windblown ridge . Average snow depth was 26.0±3.8 (mean ±standard deviation) inches, ranging from 18-36 inches deep (Figure 2). Points 1-13 paralleled the stream; points 12 and 13 entered drifts overhanging the stream. Points 14-31 were measured as the transect turned up a gentle slope onto a ridge. Hard, layered, crusts at 3 , 12, 15, and 25 inches depth from the snow surface were measured beginning at point 23 as the steeper crown of the ridge was approached. Crusting in the top layers and drifts were evidence of the effects of wind on sn01: deposition. Northerly w inds appeared to be prevalent. Snow Subsjte 1 lEl.--Subsite 1 (E) was oriented perpendicular to the stream, bisecting the small valley. Average snow depth was 28.8±4.8 inches, ranging from 22-42 inches deep (Figure 3). Surface crusting was evident as a result of wind-packing. Snow Subsjte 1lW).--Subsite 1 (W) was oriented down the stream valley. Average snow depth was 28.3±4.5 inches, ranging from 17-37 inches deep. Points 1-5 showed increasing snow depths as the partially drift-filled stream was approached (Figure 4). Points 25-38 were mea3ured from a distance approximately 30m from and parallel to the stream. Summary of Snow Site 1.-Average snow depth over all points taken at site 1 was 27.7±4.5 inches, ranging from 17-42 inches deep. Measured snow depths were heavily influenced by wind redeposition in this area. SnowStte2 Site 2 was located approximately 1 mile downstream in the s ame tributary of Jay Creek as site 1 , and about 1 0 miles upstream of the mouth of Jay Creek (Figure 1). ~ was at 3,250 ft elevation with a northerly aspect and gentle slope. Vegetation was a open shrub community of resin birch and willow. 1he single transect extended down the stream 7 valley. Average snow depth was 26.1±6.0 inches, ranging from 14-44 inches deep (Figure 5). Snow depths varied substantially within this site. Feltleaf willow showed signs of heavy past use of current annual growth twigs. Only 2 moose tracks were observed. SnowStte3 Site 3 was located approximately 1 mile downstream in the same tributary of Jay Creek as sites 1 and 2, and about 9 miles upstream of the mouth of Jay Creek (Figure 1 ). Site 3 was at 2,880 ft elevation with a northerly aspect and gentle slope. Vegetation was an open shrub community of resin birch and willow. The single transect extended down the valley along the stream. Average snow depth was 27.9±4.4 inches, ranging from 20-36 inches deep (Figure 6). Points 1-20 were on the west side of the stream parallel to and 15 ft distant, points 21-40 were on the stream, and points 41-49 were on the east side of the stream parallel to and 15 ft distant. Willows showed evidence of light past use of current annual growth twigs. Only 2 moose tracks and few signs of moose were observed . SnowStte4 Site 4 was located in Jay Creek about 6.5 miles upstream from its mouth and approximately 2.5 miles downstream of site 3 (Figure 1 ). Site 4 was at 2,650 ft elevation with a westerly aspgct 1nd gentle (3 degree) slope. Vegetation was an open shrub community of willow. The single transect extended down the valley along Jay Creek. Average snow depth was 19.8±4.5 inches, ranging from 7-28 inches deep (Figure 7). Points 1-2 were on the overflow ice of Jay Creek, while points 3-4 7 were in willows growing adjacent to the stream. Snow was deeper in adjacent shrubs than on the stream where the underlying overflow ice had rMuced snow depths. The snow had a light surface crust, but was not hard-packed. Willows showed evidence of heavy past use of current annual growth twigs. Diamondleaf ~ pulchra) and feltleaf willows were very heavily browsed. Feltleaf willow was about 5 ft tall after browsing. Abundant moose sign was present, with fecal pellets lying on top of unmelted snow. Moose had been cratering or walking through snow to gain access to the willows. The willows had been browsed since the 8 last heavy snowfall. Snow depth appeared to be comparable to the past browsing line on the shrubs. Total transect length was about 900 ft . Snow Stte5 Site 5 was located in a headwater tributary of Coal Creek approximately 20 miles upstream from its mouth (Figure 1 ). Site 5 was at 3,450 ft elevation with a southeasterly aspect and medium (15 degree) slope. Vegetation was a closed shrub community of willow. The several transects extended down the valley along the tributary stream flowing into Coal Creek. Average snow depth was 26.4±5.1 inches, ranging from 11-37 inches deep (Figure 8). Points 1-15 were on the west side paralleling the stream, points 16-30 were on the east side paralleling the stream, points 31 -45 were on the stream, points 46-60 were on the stream but about 0. 75 mile downstream of the start point, and points 61-70 were on the east side of the stream about 1 mile downstream of the start point. Willows showed little evidence of past use. Only 1 old moose track was observed. Snow Stte6 Site 6 was located in the headwaters of Coal Creek approxi mately 18.5 miles upstream from its mouth and 1.5 miles southeast of site 5 (Figure 1 ). Site 6 was at 2,940 ft elevation with an easterly aspect and gentle (3 degree) slope. Vegetation was a closed shrub community of willow. The several transects extended down the valley along Coal Creek. Average snow depth was 22.9±7.7 inches, ranging from 7-38 inches deep (Figure 9). Point 1 was on overflow ice of Coal Creek; in many places the stream had overflowed to the point that only solid ice was present. Points 2-15 were on the east side paralleling the stream; snow was wind-packed with crust layers at 3 and 12 inches from the surface. Points 16-40 w a re on the west side of the stream; low-growing diamondleaf willow and resin birch were exposed and the hard crusts in the snow profile made walking difficult. Points 41-48 were on the east side of the stream in diamondleaf and feltleaf willows. Where exposed above the snow, both diamondleaf and feltleaf willows showed evidence of heavy browsing pressure. At least 50 percent of the current annual growth twigs appeared 9 to have been removed. A preference for feltleaf over diamondleaf willow seemed to be present, though the taller height of feltleaf willow may have just made it more available . Virtually no recent browsing or moose sign was present since the last major snowfall. Only 1 moose track was observed; its direction of travel was up Coal Creek. SnowSije7 Site 7 was located on Coal Creek approximately 14 miles upstream from its mouth and 3 .5 miles southwest of Coal Lake (Figure 1 ). Site 7 was at 2,690 ft elevation with a nc.. 1easterly aspect and gentle slope. Vegetation was a closed hrub community of willow. The several transects extended down the valley along Coal Creek. Average snow depth was 27.3±3.9 inches, ranging from 21-38 inches deep (Figure 10). Points 1-17 were on the west side paralleling the stream, points 18-33 were on the stream, and points 34-53 were on the east side of the stream. Willows showed light to moderate evidence of past use . The direction of travel of most observed moose tracks was down Coal Creek. SnowStte8 Site 8 was located on Coal Creek approximately 9 miles upstream from its mouth and 5 miles downstream of site 7 (Figure 1 ). Site 8 was at 2,580 ft elevation with a northerly aspect and gentle slope. Vegetation was an open mixed forest community of spruce (~ and balsam poplar (Populus balsamifera). The several transects extended down the valley along Coal Creek. Average snow depth was 31. 7±3.6 inches, ranging from 18-40 inches deep (Figure 11 ). Points 1-15 were on the east bank paralleling 10 ft away from the stream; feltleaf willow was heavily browsed (>75%) and diamondleaf willow was lightly browsed (5-10%). Points 15-30 were on the west bank paralleling 10ft away from the stream; feltleaf willow was heavily browsed (>75%). Points 31-45 were on the west bank paralleling 40 ft away from the stream; diamondleaf willow was very lightly (<1 %) browsed. Points 46-60 were on the east bank paralleling 10 ft away from the stream; feltleaf willow was heavily browsed (>75%) and diamondleaf willow was lightly browsed (5-10%). Points 61-75 were on the east bank paralleling 40ft away from the stream; 10 d iamondleaf willow w as very lightly (<1%) browsed. Poi nts 76-102 w ere on the east bank parallel i ng 1 0 ft away f rom the stream . SoowStte9 Site 9 was located on lower Coa l Cre'9 k approxi mately 6 m i les u pstream from it s mouth and 3 miles downstream of s ite 8 (Figure 1 ). Site 9 was at 2 ,500 ft elevation w ith an eastern aspect and gentle (1 degree) slope. Vegetation was an open shrub com munity of willow along Coal Creek and an adjacent closed community of spruce. The sev~ral transects extended down the vall ey along Coal Creek. Average snow depth was 26.8±6.0 inches, ranging from 15-36 inches deep (Figure 12). Points 1-17 were on th e w est bank paralleling the stream; feltleaf willow was heavily browsed w ith decadent and d ead stems , and lack of cru ,..t s in the snow profile suggested that the area was protected from w ind. Points 18-19 were on the ice overflow of the stream. Points 20-29 were on a small is land within the stream banks; feltleaf willow were decadent and there were abundant old moose tracks . Points 30-53 left the stream and entered a stand of tall white spruce (~ glauca); Richardson willow ~ larJ.ata) was exposed in moose tracks , recent moose tracks suggested they were just walking around because no crater ing was evident, and t he area appeared to be sheltered from the wind. Points 54-61 were on overflow stream ice . Po ints 62-69 were on a small island within the stream banks; there was little evidence of w i nd action on the snow in this area, and decadent feltleaf willow on the island had experienced removal of about 50% of its current annual growth twigs . Throughout the streamside area, shrubs showed evidence of very heavy browsing pressure in their past. Snow SUe 10 Site 10 was located at the mouth of Coal Creek (Figure 1}. Site 10 was at 2,390 ft elevation with a easterly aspect and gentle slope. Vegetation was a closed shrub community of willow along Coal Creek and an adjacent open community of spruce. The several transects extended down the valley along Coal Creek and onto an adjacent island. Average snow depth was 24 .9±5.2 inches, ranging from 15-33 inches deep (Figure 13). Points 1-17 were on 1 1 the east bank of the stream, points 18-35 were on a gravel bar on the stream , and points 36-52 were on a island dominated by spruce. Browsing pressure was variable , rang ing from light to moderate. Moose tracks and sign were abundant Snow Stte11 Site 11 was located about 1.5 miles south of the mouth of the Oshetna River on th e upland bench (Figure 1 ). Site 11 was at 2,550 ft elevation on a easterly aspect with a gentle (5 degree) slope. Vegetation was an open shrub community of res in birch and w ill ow. The s i ngle transect travelled south through scattered black spruce (Pjcea mariana). Average snow depth was 22.3±2.7 inches, ranging from 18-30 inches deep (Figure 14). Several scattered moose tracks and pits where moose were cratering for diamondleaf willow and resin birch were observed. The tips of most shrubs were just protruding above the snow level. Only a light surface crust on the snow suggested that the area may not experience frequent winds. The general area appeared to receive moderate to heavy use, although caribou lRangifer tarandus) tracks may have contributed to the sign observed . Snow Stte 12 Site 12 was located about 2 miles south of the mouth of the Oshetna River on the upland bench, and about 0.5 miles southwest of site 11 (Figure 1 ). Site 12 was at 2,550 ft elevation, which was the same e evation as site 11, with a flat aspect and slope. Vegetation was an open shrub community of resin birch and willow. The single transect travelled in a southeasterly direction. Average snow depth was 19.9±3.3 inches, ranging from 10-26 inches deep (Figure 15). A semi-hard surface crust was present in the snow profile. Evidence of light browsing (<1 0%) was observed on diamondleaf and Richardson willows . No fresh moose tracks were observed. Snow Stte 13 Stte 13 was located about 0. 75 mile southeast of the mouth of the Oshetna River on an old river terrace lower in elevation than sites 11 and 12 (Figure 1 ). Site 13 was at 2 ,200 ft elevation with a flat aspect and slope. Vegetation was an open forest community of spruce 1 2 an d an open shru b community of resin birch and willow. The single transect trav lied in a northerl y d irect ion. Aver age snow depth was 20.5±2.0 inches, ranging from 18-24 inches deep (Figure 16). Approxi mate ly 50 % of th e ex posed tips of resin birch had been browsed . Snow Sjte 14 Site 14 was located at the mouth of Jay Cre ek on an island alo ng the Susitna River (F igure 1 ). Site 14 was at 1,725 ft elevat ion on a westerly aspect with a gen tle (3 degree) slope . Veg etation on the is land was an ope n shru b commun ity of willow alo ng th e Sus it a River and an adjacent open commun ity of spruce and large balsam pop lar . Th e tra nsect extended downriver through the will ows along the edge of the island , the n t urned into the adjacent spruce and balsam poplar. Average snow depth was 17 .2±4 .0 inches , rangi i;g from 7-21 inches deep (F igure 17). Points 1-17 were through the willow band betw een the spnJce to the south and the river channel to the north; feltleaf and diamond teaf willows and balsam poplar twigs were heavily browsed, some drifting of snow was observed , and most of the snow had been disturbed by cratering and walking moose. Points 18-25 were in th ick wh it e spruce trees with feltleaf willow in the un derstory . Points 26-33 were beneat h a tall, closed white spruce canopy with scattered alder (Alnus) in th e. understory; moose tracks appeared to be just passing through as there was no browse present. Points 34-40 returned to the bank of the river into feltleaf willow and balsam poplar ; both had been heavily browsed . Three moose were observed as we approached to land at site 14. Snow Stte 15 Site 15 was located on a terraced bench 0.5 mile southwest of the mouth of Jay Creek (Figure 1 ). Site 15 was at 2,050 ft elevation on a northerly aspect with a gent le slope . Vegetation was an open forest community of white spruce. The transect crossed the terraced bench. Average snow depth was 19.5±6.9 inches , ranging from 8-34 inches deep (F igure 18). Diamondleaf willow appeared to have been browsed in early winter , but was mostly unde r snow at that time. The understory was dominated by resin birch. 1 3 ~ Site 16 was located on the upland slopes above the Susitna River 3 .5 miles southeast of the mouth of Jay Creek (Figure 1). Site 16 was at 3 .100 ft elevation on a north erl y aspect with a gentle slope. Vegetation was a closed shrub community of resin birch , willow , and alder. Average snow depth was 22.3±3.6 inches, ranging from 13-30 i nch s deep (Figure 19). A surface crust was present in the snow profile. Felleaf and diamondleaf wiiiONS showed evidence of moderate browsing pressure. Alder had been browsed on the ti ps of twigs. A few moose tracks were observed. SnowStte 17 Site 17 was located in the Watana Creek floodplain approximately 1 mile upstream of its mouth (Figure 1 ). Site 17 was at 1 ,600 ft elevation on a southerly aspect with a gentle (3 degree) slope. Vegetation was an open shrub community of willow. The transect began by heading upstream through the willows, then turned into the open white spruGe forest to the east. Average snow depth was 23.1 ±1.9 inches, ranging from 19-27 inches deep (Figure 20). Points 1-13 were in feltleaf willow within the floodplain; no crusts were present in the snow profile, and almost all current annual growth of feltleaf willow had been removed . T he browsed condition of the feltleaf willow was much as would be expected if observed during late spring. Points 14-18 were on Watana Creek overflow ice. Points 19-43 were in white spruce; some feltleaf and diamondleaf willows were present in the understory and were heavily browsed. Moose tracks were observed travelling through, but no cratering was noted. No fresh moose sign was noted since the last major snowfall. Snow Site 18 Site 18 was located on the terraced bench approximately 1.5 miles southwest of the mouth of Watana Creek (Figure 1). Site 18 was at 2,250 ft elevation with a flat aspect and slope. Vegetation was a dwarf forest community of white spruce with a graminoid understory. The transects criss-crossed a flat area dominated by graminoids and diamondleaf willow. Average snow depth was 18.0±5.9 inches, ranging from 6-33 inches 4 deep (Figure 21 ). Hard crusts in the snow profi le and var iability in snow depths we re evidence of the effects of wind in this exposed area. Moose had been cratering for diamondleaf will ow . Snow Sjte 19 Site 19 was located on the uplands approximately 4 miles south -southwest of the mouth of Watana Creek (Figure 1 ). Site 19 was at 2,600 ft elevation with a northwesterly aspect and gentle slope . Vegetation was an open forest community of black and white ~pruce with an understory of resin birch and willow. Av erage snow depth was 17 .4 ±11 .2 inches , ranging from 3-45 inches deep (Figure 22). Hard crusts in the snow prof ile and vari ability in snow depths were evidence of the effects of wind in this higher elevat ion are a. Snow was deeper in the more protected willow (po ints 6-12) and black spruce (points 21- 27) stands. Feltleaf willow were large, decadert, and heavily browsed. Approx imately 50% of the current annual growth of diamondleaf willow had been browsed. Snow Sije 20 Site 20 was located in the headwaters of the east fork of Watana Creek approx im ately 19 miles upstream f rom the mouth (Figure 1). Site 20 was at 3,300 ft elevation with a southerly aspect and gentle (5 degree) slope. Vegetation was an open shrub co 11 munity of resin birch and willow. The transect travelled down the stream valley parallel to Watana Creek. Average snow depth was 44.4±9.8 inches, ranging from 21-55 inches deep (Figure 23). Points 1-15 and 20-25 were in and between 9 ft tall diamondleaf willows that had received virtually no browsing. Points 16-19 were on stream overf low ice . Numerous extremely hard crusts caused by wind-packing were present in the snow profile . Winds appeared to be predominantly from the north and east, and had blown the snow from exposed ridges. No moose sign was observed. Snow Sije 21 Site 21 was located in the headwaters of the east fork of Watana Creek approximately 17 miles upstre am from its mouth and 2 miles downstream of site 20 (Figure 1 ). Site 21 1 s was at 3,000 ft elevation with a southerly aspect and gentle slope. Vegetation was an open shrub community of resin b irch and willow. The transect travelled down the stream valley parallel to and about 20-40 ft from Watana Creek Average snow depH was 30.8±4.1 inches, ranging from 21-38 inches deep (Figure 24). Snow hardness varied from hard to soft with no cru st layers. Diamondleaf (about 20%) and Richardson w illows were moderately browsed, but feltleaf willow had been heavily browsed by moose. The area wa.~ heavily utilized by w intering moose ; about 50 animals were observed in th is general area of Watana Creek. Snow Sije 22 Site 22 was located in t h e east fork of Watana Creek appro xi mately 1 0 miles upstream from its mouth and 4 miles upstream of the confluence of the east and west forks of Watana Creek (Figure 1 ). Site 22 was at 2,800 ft elevation with a northerly aspect and gentle to moderate slope. Vegetation was an open forest community of black and white spruce. The transect was located on the valley slopes 0 .25 mile above Watana Creek. It travelled around the hillside toward the west, paralleling Watana Creek. Average snow depth was 24.6±5.0 inches, ranging from 17-36 inches deep (Figure 25). A surface crust layer was present but variable. Diamondleaf willow was noted to be moderately to heavi ly browsed. Numerous moose tracks and other sign was o~ Jed. Alder had not been browsed. Snow Sije 23 Site 23 was located in Clark Creek approximately 4 miles upstream of the confluence of Clark Creek and Tsusena Creek (Figure 1). Site 23 was at 2,750 ft elevation with a southwesterly aspect and flat slope. Vegetation was a closed shrub community of resin birch, willow, and alder. Average snow depth was 43.0±3.2 inches, ranging from 35-49 inches deep (Figure 26). Only light to moderate browsing of current annual growth twig~ of feltleaf willow had occurred, though the shrubs showed evidence of past heavy browsing pressure. No moose tracks were observed . 16 Snow Site 24 Site 24 was located on Tsusena Creek at the confluence of Clark Creek and Tsusena Creek, approximately 4 miles downstream of site 23 (Figure 1 ). Site 24 was at 2,380 e1evation with a southerly aspect and gentle slope. Vegetation was a woodland forest community of white spruce. The transect paralleled Tsusena Creek. Average snow depth was 35.1±2.9 inches, ranging from 28-42 inches deep (Figure 27). Points 1-31 were along the west bank of Tsusena Creek; feltleaf willow ·was neavily browsed with 90-100% of the twigs removed. Points 32-57 were on a knoll40 ft from Tsusena Creek, and points 58-71 were travelling from the knoll back to the bank of Tsusena Creek. Points 72-77 were again along the west bank of Tsusena Creek; feltleaf willow along the stream was all heavily browsed. Most browsing appeared to have occurred earlier during the winter as no fresh moose sign was observed. Snow Site 25 Site 25 was located at the mouth of Tsusena Creek along the Susitna River (Figure 1 }. Site 25 was at 1,510 ft elevation with a westerly aspect and gentle (1 degree) slope. Vegetation was a woodland forest community of white spruce. The transect began on the bank ice paralleling the Susitna River crossing the mouth of Tsusena Creek, and then travelled into the forest on the west bank of the stream. Average snow depth was 28.6±2.6 inches, ranging from 23-34 inches deep (Figure 28). Points 1-16 were on ice along the north side of the Susitna River. Points 17-36 were in a white and black spruce forest on the west bank of Tsusena Creek; absence of crusts in the snow profile suggested a lack of wind in this area, snow was less deep directly beneath the crowns of spruce trees than between them, and moose tracks were noted to travel between spruce trees where evidence was found of moose feeding on mountain cranberry (Vaccinium vitis-idaea) and low-growing willows in the shallower snow beneath the tree crowns. 1 7 Snow Sjte 26 Site 26 was locat ed at the mouth of Devil Creek along the Susitna River (Figure 1 ). Site 26 was at 1,110 ft elevation with a southerly aspect and gentle to 30 degree slope . Vegetation was a closed mixed forest community of spruce and paper birch (Bet ula papyrjfera). The transect extended along the banks of th u itna River and Devil Creek. Average snow depth ·.vas 27.9±9.9 inches, ranging from 9-55 inches deep (Figu r e 29). Points 1-9 were 1 0 ft off the north bank of the Susitna River; paper birch and alder had been lightly browsed . Points 10-20 were 30 ft off the north bank of the Susitna River ; paper birc h had been browsed and a single moose track was observed. Points 21-61 were a lo ng t he east bank of Devil Creek. Points 62-96 were along the Su sitna River; the shallow depths in the first part of this section suggested measurements were on overflow ice . Po ints 97-132 were on a hill adjacent to the north side of the Susitna River; paper birch and alder had been browsed. Points 133-158 were along the north bank of the Susitna River; the shallow depths in the fi rst part of this section suggested measurements were on overflow ice, and the 2 points 150 and 151 were measured in a snow sluff off an adjacent rock cliff. Snow Stte 27 Site 27 was located 5.5 miles upstream of the mouth of Devil Creek (Figure 1 ). SitP. 27 was at 2,525 ft elevation with a easterly aspect and gentle (5 degree) slope. Vegetation was a closed shrub community of willow and resin birch. The transect extended along the banks of De ·:Creek and then turned toward the distant western valley hillside . Average snow dept '1 was 43 .3±7.4 inches , ranging from 31-63 inches deep (Figure 30). Points 1- 13 were oriented through the willows along the west bank of Devil Creek heading north ; hard crusts were in the snow profile, feltleaf (90-1 00%) and diamondleaf (70%) willows were heavily browsed, the main stems of many feltleaf willow were broken off by foraging moose, anc furrows formed by moose plowing through chest-deep snow were observed . Points 14-47 turned to the west away from the stream toward the valley hillsides ; deep snow was present in depressions filled by blowing snow (P q ., points 21-25 and 46-47), 1 8 diamondleaf willow was less heavily browsed on the hillsides than nearer Devil Creek, and inds were primarily from the north or northeast. Snow Sjte 2EI Site 28 was located 9 miles upstream of the mouth of Devil Creek, and 3 .5 miles upstream of site 27 (Figure 1 ). Site 28 was at 2, 750 ft elevation with a south- southwesterly aspect and gentle slope. Vegetation was an open shrub community of willow and resin birch. The transect was adjacent to Devil Creek. Average snow depth was 42.9±11.4 inches, ranging from 22-64 inches deep (Figure 31 ). Feltleaf and diamond leaf (65%) willows were heavily browsed. No moose sign was observed. Snow Stte 29 Site 29 was located on the southwest shore of Stephan Lake (Figure 1 ). Site 29 was at 1 ,862ft elevation with a flat aspect and slope. Shoreline vegetation was a closed forest community of spruce. The transect was on and adjacent to Stephan Lake. Average snow depth was 30.3±1 0.6 inches, ranging from 10-45 inches deep {Figure 32). Points 1-5 were on overflow ice of Stephan Lake. Points 6·30 were in the shoreline spruce forest; snow immediately. became deeper as the observer moved from 1ake ice onto the s hore ( .g ., between points 5 and 6), snow depths stabilized around 39 inches deep within the trees, ar.d not much evidence of drifting was observed. Points 31-51 were in a graminoid-dominated summer bog; points 32 and 33 were on overflow ice from a small stream, and there w as some evidenc""' of drifting. Points 52-59 were again on lake ice. No moose sign was observed. Winds appeared to be a rather infrequent event on this lai-\e. Snow Stte 30 Site 30 was located along a tributary of Prairie Creek, 2 miles southeast of site 29 {Figure 1 ). Site 30 was at 2,200 ft elevation with a southwesterly aspect and gentle (5 degree) slope. Vegetation was a closed forest community of spruce and paper b1rch and an open shrub community of willow. The transect extended down the tributary stream . Average snow depth was 39.1±3.4 inches, ranging from 32-50 inches deep {Figure 33). 1 9 Points 1-80 were through a willow dominated shrub community; diamondleaf, f el tleaf, and Richardson willows wer all moderately to heavily browsed. Points 81-89 were in an adjacent spruce forest Only old moose sign was observed, implying the area had prim aril y been used earlier during the winter. Snow Site 31 Site 31 was located near upper Prairie Creek about 2 miles s utheast of site 30 (Figure 1 }. Site 31 was at 2,500 ft elevation w ith a north-northwesterly aspect and gentle slope. Vegetation was an open shrub community of willow. The transect extende d along the tributary st ream. Average snow depth was 37.5±2.6 inches, ranging from 32-42 inches deep (Figure 34}. Feltleaf willow was he avily browsed. Only old moose sign was observ ed, implying the area had primarily been used earlier during the winter. 5.2 Winter Bird Transect Site Descriptions Bird Transect 1 Bird transect 1 was located on the north side of the Susitna River approximately 1 mile downstream of the mouth of Fog Creek (Figure 35}. Elevations ranged from 1,370- 1,700 ft with a southerly aspect and gentlb .,J steep slopes. The transect began near the bank and ran parallel to the Susitna River to the west, then turned upslope to the north, then turned east contouring around the slope, and then turned southeast returning to the point of origin (Figure 35}. Vegetation along the transect was prima rily closed spruce and mixed spruce-paper birch forests. Average snow depth was 32.5±2.4 inches, ranging from 26- 38 inches deep (Figure 36}. Sample points from 0845-1130 and 1415-1515 were at eievaticns below the Devil Canyon maximum high pool level of 1,466 ft, while points 1145-1400 were above that elevation. A light surface crust was noted to be ~resent. Snow depths remained relatively consistent throughout the closed forests crossed by this transect. Bird Transect 2 Bird transect 2 was locate d on the north side of the Susitna River across from the mouth of Fog Creek (Figure 35}. Elevations ranged from 1,370-1,900 ft with a 20 southwesterly aspect and gentle to steep slopes. The transect began near the bank and ran north along the Susitna River, then turned upslope to the west, then turned southwest contouring around the slope, and then turned southeast returning to the point of origin (Figure 35). Vegetation along the transect was primarily closed spruce and mixed spruce- paper birch forests. Average snow depth was 30.2±2.6 inches, ranging from 25-34 inches deep (Figure 37). Sample points from 0830-1200 and 1430-1445 were at elevati ons below the Devil Canyon maximum high pool level of 1 ,466 ft, while points 1230-1415 were above that elevation. Snow depths remained relatively consistent throughout the closed forests crossed by this transect. A light surface crust was noted to be present. Bird Transect 3 Bird transect 3 was located on the north side of the Susitna River near the mouth of Watana Creek (Figure 35). Elevations ranged from 1,550-2,020 ft with a southerly aspect and gentle to steep slopes. The transect began near the mouth of Watana Creek and ran upslope o the northeast and parallel to the stream, then turned upslope to the southeast, then turned back downslope to the southwest returning to the point of origin (Figure 35). Vegetation along the transect was primarily mixed spruce-paper birch forests at the lower elevations and woodland spruce and resin birch at the higher elevations. Average snow depth was 25.0±2.5 inches, ranging from 19-30 inches deep (Figure 38). All sample points were at elevations below the Watana Stage Ill maximum high pool level of 2,200 ft. Snow depths remained relatively consistent throughout the area crossed by this transect. The snow was noted to be soft and po.vdery. Bird Transect 4 Bird transect 4 was located on the north side of the Susitna River between Sally Lake and the mouth of Watana Creek (Figure 35). Elevations ranged from 1 ,550-2,1 00 ft with a southerly aspect and gentle to steep slopes. The transect began at the edge of Sally Lake and ran generally across the slope to the southwest toward the Susitna River, then turned westerly and contoured near the top of the steep slope above the canyon, ending at the mouth 21 of Watana Creek (Figure 35). Vegetation along the transect was primarily mixed spruce- paper birch forests at h e lower elevations and woodland spruce and resin birch at the higher elevations. Average snow depth was 20.3±2.5 inches, ranging from 15-25 inches deep (Figure 39). All sample points were at elevations below the Watana Stage Ill maximum high pool level of 2,200 ft. Snow depths remained relatively consistent throughout the area aossed by this transect The snow was noted to be soft and powdery. Bjrd Transect 5 Bird transect 5 was located on the north side of the Susitna River northwest of the mouth of Kosina Creek (Figure 35). Elevations ranged from 1 ,620-2,600 ft with a southerly aspect and gentle to steep slopes. The transect began at the edge of a small lake situated on the uplands northwest of the mouth of Kosina Creek, travelled in a generally straight line to the west-northwest for about 3 miles, then turned south and ended on the banks of the Susitna River (Figure 35). Vegetation along the transect was primarily open and closed spruce forest. Average snow depth was 19.3±4.1 inches, ranging f r om 11-25 inches deep (Figure 40). Sample points from 1115-1300 were at elevations above the Watana Stage Ill maximum t . gh pool level of 2,200 ft, while points 1315 -1530 were below that elevation. Snow depths were variable, but on the average appeared to be deeper at the higher elevations between points 1115-1315 than at the lower elevations nearer the river (Figure 40). Bird Transect 6 Bird transect 6 was located on the north si d e of the Susitna River northwest of the mouth of Kosina Creek (Figure 35). Elevations ranged from 1,640-2,700 ft with a southerly aspect and gentle to steep slopes. The transect began at the edge of the same small lake situated on the uplands northwest of the mouth of Kosina Creek where bird transect 5 began but at the opposite end, t ravelled to the northeast, then turned south-southwest, and then turned west where it ended on the banks of the Susitna River (Figure 35). Vegetation along the transect was primarily open and closed spruce and mixed spruce-paper birch 22 forests. Average snow depth was 22 .1 ±2.8 inches, ranging from 17-27 inches deep (Figure 41). Sample points from 1115-1330 were at elevations above the Watana Stage Ill .,aximum high poo l level of 2,200 ft, while points 1345-1615 were below that elevat:oo. Snow depths were variable, but on the average appeared to be deeper at the higher elevations between points 1115-1315 than at the lower elevat ions nearer the river (Figure 41 ). 5. 3 Corrparisons Among Sites Snow sites were conducted in sets of 3 or more because there were 3 observers . Often, sites were selected following a drainage valley; this was the case for Jay, Coal , Watana, Clark/Tsusena, and Devil Creeks. Because sites located along drainages generally followed elevational gradients, average snow depths among adjacent sites within those drainages were compared. Snow depths were averaged across all measurements taken at a site, including those in drifts and on overflow ice. For comparison, sites were plotted on figures by decreasing elevation within each drainage (see Figure 1 ). Average snow depths in Jay Creek decreased from about 28 inches at site 1 to approximately 17 inches at site 14; a decline in elevation of about 1,850 ft (Figure 42). There appeared to be no difference by elevation along Coal Creek, averaging 27 inches for the 5 sites (Figure 43). Greatest difference in average snow depths by elevation occurred in the Watana Creek drainage, with 44 inches at elevation 3,300 ft and 23 inches at elevation 1,600 ft (Figure 44) Average snow depths in the Clark/Tsusena Creek drainage decreased from 43 inches at elevation 2, 750 ft to 29 inches at elevation 1,51 0 ft, a decline of 1,240 ft. (Figure 45). Average snow depth was lower at site 26 at the mouth of Devil Creek than at either of t he other higher elevation sites withira that drainage (Figure 46). When elevation of all 31 sites was compared with average snow depths, no trend was apparent (Figure 47). Selected sites covered a broad geographical ra nge between Coal Creek and Devil Creek, and regional differences were expected. The maritime influence in the transitional climatic zone of the project area west of Tsusena Creek probably were a major 23 factor influencing snow depth relative to elevati()f'l at sites withi r. that region . To the east of Tsusena Creek the proj ect area appeared to become increasingly drier as the continental climatic zone was approached and the area entered the rain shad w of the Talkeetna Mountains. Other major factors that presumably could influence snow depth differences among the sites were movement of storm systems, topographic variation, and changes in latitude. 6 CB:l.SSK:N As anticipated, snow depths varied Considerably within sites. Wind action , caus ing snow drifts and filling of depressions, resulted in variation. Snow depths were generally less when taken from atop overflow of frozen streams, lakes, or the Susitna River , where the underlying water had melted or incorporated snow in formation of the ice. Snow tended to be deeper in protected areas such as in denser vegetation (e.g., spruce forests and tall shrubs) than in open areas (e.g., low shrubs). Relatively little crusting was found at any site except those that had experienced wind-packing. Wind-p3cking was particularly evident in the exposed portions of the higher elevation sites such as upper ends of drainages ard on exposed ridges. Variation in snow depths was also affected by direction, distance, and length of transects placed within sites by individual observers. This was left entirely to the discretion of each observer, who was given only the guideline to obtain samples representing the variat;;:,n present at a site. Variation among observers was apparent as each sought to sample portions of sites of particular interest to that individual. The samples were obviously not randomly distributed, but when all points were t~!cer'! as a whole and averaged across all poi r...3 sampled they may have pproximated the mean snow depth at a site. Variation among sites was not explainable by elevational differences alone . Other unmeasured variables may account for these differences. Within a drainage, snow depths generally decreased with decreasing elevation. Generally, average snow depths increased from east to west over the basin in spite of decreases in elevation over that same gradient. ... 2 4 The magnitude of increase in snow depths in the western portion of the study area was also probably affected by the year it was sampled; winter 1985 was a particularly deep snowfall year of record for the lower Susitna basin, the effects of which extended north of Talkeetna into Devil Canyon (SCS 1985). 7 PFnECT MPLCATOJS Given the limitations of the data collected from this s ing le snow survey where sampling was by non-random techniques, conclusions drawn from this study must be viewed as tentative and subject to individual interpretation. The results presented here suggest that snow depths deer ase from hight.'r elevat ions to lower elevations. These findings tend to support the hypothesis of Ba llard et at . (1983, 1984) concerning patterns of moose movements over elevational gradients in the middle Susitna River basin. Snow depths also appear to decrease from west to east in th e s udy area The importance of snow depths to moose are basically 2-fold: snow accumulat ion 1) restricts locomotion, and 2) covers food resources. The majority of tracks and other sign of the presence of moose were found along riparian drainages where forage resources of primarily willow were concentrated. This was particularly ·dent along upper Watana Creek (e.g., site 21) where numerous moose were concentrated around their sim il arly concentrated food source in spite of the almost 31 ir,..f-)es of snow. This suggests that moose concentrate during winter at locally available food sources even when snow depths approach those that would otherwise restrict movements. Othe r observational evidence collected during this study substantiates previous observations of Ballard et al. (1982, 1983 , 1984) that moose will move from previously used areas to areas of lesser snow depths when accumulated snow restricts movements or covers forage resources (e.g., sites 7, 8, 9, 4 , 24 , 27, 28, 30, and 31 ). · Moose ~ign that we examined during late-winter 1985 appeared to be concentrated in areas occupied by feltleaf willow. Feltleaf willow usually grows in ass ciation with 25 riparian areas or on disturbed sites, and at all sites where nota ion was made it w as alw ays more heavil y browsed than other willow species with which it grew in associ ation. It is also t h e dominant w illow s p ecies grow i ng i n ripar ian areas along t he Susitna River. F el tleaf willow is tall -g r owing, and protrudes above t he snow w hen other shorter w illow speci es become covered . M ose movement and population data (B all ard et al. 1983, 1984), and subj ective observations f rom th is stud y suggest that d uring late winter m oose oncentrate in lower elevation r i pari an zones where s now is l es s deep and foods such as feltleaf willow protrude above the snow. Loss of lower elevation hab itats suppo rti ng concentrated forage resources and having lower snow depth accumu l at i ons w ·n have an advers e impact on wint ering moose populations. 8 UTERAlURE CITED Ba ll ard, W.B., C .L Gardner, J.H. Westlund, and J.R. Dau . 1982. Big game studies, V Ill, Moose -Upstream. Susitna Hydroelectric Project. Phase I f i nal report by the A laska Dept. of Fish and Game to the Alaska Power Author ity . Anch o rage . 199p p. plus appendices. __ , J .S. Whitman, N.G. Tankersley, LD. Aumiller, and P. Hessing. 1983. Bi g ga m e studies, Vol. Ill, Moose -Upstream. Susitn a Hydroelectric Project. Phase II progress report by the Alaska Dept. of Fi sh and Game to the Alaska Power Au thor ity. Anchorag e. 141 pp. __ , ____ _. __ ____, and . 1984. Big game studies, Vol. Ill, Moose - Upstream. Susitna Hydroelectric Project. Annual report by the Alaska Dept. of Fish and Game to the Alaska Power Author ity. Anchorage. 147pp. ----' __ __, and C.L. Gardner. 1985. Moose -Upstream. Susitna Hydroelectric Project. Annual r eport by the Alaska Dept. of Fish and Game to the A laska Power Authority. Anchorage. 48pp. Coady, J .W . 1974. Influence of snow on behav ior of moose. Can. Nat. 101:417-436. 26 Herter, D. 1985. W inter bird populations in forest habitats ot the middle Susttna River basin, Alaska. Susitna Hydroelect ·c Project. Report by LGL Alaska Re earch Associates, Inc. under contract to Harza-Ebasco Susitna Joint Venture for the Alaska Power Authority . Anchorage . 24pp. Kelsall, J .P., and E.S. Telfer. 1974. Biogeogra( y of moose with particular reference to westem North America. Can. Nat. 101:1 ·i 7-130. LeResche, A. E. 197 4 . Mooc;e migrations in North America. Can . Nat. 1 01 :393-415. SCS (Soil Conservation Service). 1985. Snow surveys and water supply outlook for Alaska . U.S. Dept. Agric. Soil Conser. Serv . Rep. March . 13pp. Telfer, E.S. 1970. Winter habitat selection by moose and white-tailed deer. J. W ildl. Manage. 34:533-559. Viereck, L.A., C.T. Dymess, and A.A. Batten . 1982. Revision of preliminary classificat ion for vegetation of Alaska. Unpublished report from Anchorage Worksh """' on Classification of Alaskan Vegetation, December 24, 1981. 72pp. FIGURE © 0 0 10 Mile a 10 20 Kllometera 20 30 Figure 1. March 1111 anow depth auner altea In the Middle lualtna River baaln. Alaaka . N -..1 28 Snow Silll 1(8) 65 65 60 60 55 55 50 50 45 45 SnowOeplh 40 40 (inches) 35 35 30 30 25 I 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 31 Sequential Sample Points Figure 2. Snow depths at sequential sample points for snow site 1 (8). 29 Snow Site 1(E) 65 65 60 60 55 55 so 50 45 45 Snow0ep4h 40 40 (inches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 31 36 Sequential Sample Points Figure 3. Snow depths at sequential sample points for snow site 1 (E). 30 Snow !)ita 1 (W) 65 65 60 60 55 55 50 50 45 45 SnowDapch 40 40 (inches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 31 36 Sequential Sample Points Figure 4. Snow depths at sequential sample points for snow site 1 (W). 31 SnowSitll 2 65 65 60 60 55 55 so 50 45 45 SnowDeplh 40 40 (inches) 35 35 30 30 25 25 20 20 15 15 10 10 l 5 5 0 0 6 11 16 21 26 31 Sequential Sample Points Figure 5. Snow depths at sequential sample points ~or snow site 2 . 32 SnowSite3 65 65 f.J 60 55 55 50 50 45 45 SnowDeplh 40 40 (inches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 31 36 41 46 Sequential Sample Points Figure 6. Snow depths at sequential sample points for snow site 3. 65 60 55 50 45 SrowOepl'l 40 (inches) 35 30 25 20 15 10 5 0 SnowSite4 33 65 60 55 50 45 40 35 30 25 -4H~ .. ~~~.---~HH.---~---r-------. .. ~HH.-~~~20 15 10 5 II ~~~~~~~~~~~~.~~~~~~~~~~~~~~~0 6 11 16 21 26 31 36 4 1 46 Sequential Sample Points Figure 7 . Snow depths at sequential sample points for snow site 4 . 3 4 Sncr.v Site 6 65 65 60 60 55 55 50 50 45 45 Sncr.v Deplh 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 31 36 41 46 Sequential Sample Points Figure 9. Snow depths at sequential sample points for snow site 6. Snow Site 5 65 60 55 50 45 Snow Depth 40 (i nches) 35 30 25 20 15 10 5 0 6 11 16 21 26 31 36 41 46 51 56 61 66 Sequential Sample Point& Figure 8. Snow depths at sequential sample points for snow site 5. 35 65 60 55 50 45 40 35 30 25 20 15 10 5 0 36 Snow Site 7 65 65 60 60 55 55 50 50 45 45 SnowDeplh 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 3 1 36 41 46 5 1 Sequential Sample Points Figure 10. Sr1ow depths at sequential sample points for snow site 7. 37 SnowSite8 65 65 60 60 55 55 50 50 45 45 Snow Depth 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 10 1 Sequential Sample Points Figure 11. Snow depths at sequential sample points for snow site 8. 3 SnowSit89 65 65 60 60 55 55 50 50 45 45 SnowOeplh 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 31 36 41 46 51 56 61 66 Sequential Sample Points Fi gure 12 . Snow depths at sequential sample po ints for snow site 9. 3 SnowSite 10 65 65 60 60 55 55 50 50 45 45 SnowOeplh 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 31 36 41 46 5 1 Sequential Sample Points Figure 13. Snow depths at sequential sample points for snow 5ite 10 . SnowSit.11 65 65 60 60 55 55 50 50 45 45 Srow Oeplh 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 Sequential Sample Points Figure 14 . Snow depths at sequential sample points tor snow site 11 . 4 1 SnowSit.12 65 65 60 60 55 55 50 50 45 45 Snow Depth 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 Sequential Sample Po ints Figure 15. Snow depths at sequential sample points for snow site 12. 4 2 SnowSi .. 13 65 65 60 60 55 55 50 50 45 45 SrowDeplh 40 40 (inches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 Sequential Sample Points Figure 16. Snow depths at sequential sample points for snow site 13. 4 3 Snow Site 14 65 65 60 60 55 55 50 50 45 45 SnowDeplh 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 31 36 Sequential Sample Po ints Figure 17. Snow depths at sequential sample points for snow site 14. 44 SnowSite15 65 65 60 60 55 55 50 50 45 45 SrowDepth 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 Sequential Sample Po ints Figure 18. Snow depths at sequential sample points for snow site 15. 4 5 Snow Site 16 65 65 60 60 55 55 50 50 45 45 Snow Depth 40 40 (inches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 Sequential Sample Po ints Figure 19. Snow depths at sequential sample points for snow site 16. 4 I SnowSite17 65 65 60 60 55 55 50 50 45 45 SrcwDeplh 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 31 36 41 Sequential Sample Points Figure 20. Snow depths at sequential sample points for snow site 17. 47 Snow Site 18 65 65 60 60 55 55 50 50 45 45 Snow Depth 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 II 10 5 I 5 0 0 6 11 16 21 26 31 36 41 Sequential Sample Points Figure 21. Snow depths at sequential sample points for snow site 18. 4!? Snow Site 19 65 65 60 60 55 55 50 50 45 45 Snow Depth 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 Sequential Sample Po ints Figure 22. Snow depths at sequential sample points for snow site 19. 49 Snow Site 20 65 65 60 60 55 55 so so 45 45 Snow Depth 40 40 (in ches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 Sequential Sample Po in ts Figure 23 . Snow depths at sequential sample points for snow site 20. 50 Snow Site 21 65 65 60 60 55 55 so 50 45 45 Snow Depth 40 40 (inches ) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 Sequential Sample Po ims Figure 24. Snow depths at sequential sample points for snow site 21. 51 Snow Site 22 65 65 60 60 55 55 50 50 45 45 Snow Depth 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 Sequential Sample Points Figure 25 . Snow depths at sequential sample points for snow site 22. 52 Snow Site 23 65 65 60 60 55 55 50 50 45 45 Snow Depth 40 40 (inch es) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 Sequenti al Sample Po ints Figure 26. Snow depths at sequential sample points for snow site 23 . 65 60 55 50 45 SrowDepth 40 (i nches) 35 30 25 20 15 10 5 0 SrowSite 24 6 11 16 21 26 31 36 41 46 5 1 Sequential Sample Poi nts 56 61 66 71 Figure 27. Snow depths at se uential sample point s for snow site 24 . 53 65 60 55 50 45 40 35 30 25 20 15 10 5 0 76 65 60 55 50 45 Snow Depth 40 (i nches) 35 30 25 20 15 10 5 0 Snow Site 25 5 4 65 60 55 50 45 40 35 30 25 20 15 10 5 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 0 6 11 16 21 26 31 36 Sequential Sample Points Figure 28 . Snow dep ths at sequential sample points for snow site 25. s.-Sho26 65 60 55 50 45 51.-[)optl 40 (onches) 35 30 25 20 15 10 5 0 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 i1 Sequor<lal Samplo Poln111 Figure 29 . Snow depths at sequential sample points for snow site 26. Sl.-Sito 26 86 101 1()6 111 116 121 126 131 136 141 146 151 156 ~nl.al Samplo I'W>III 65 60 55 50 45 40 35 30 25 20 15 10 U1 U1 65 60 55 50 45 Snow Depth 40 (inc hes) 35 30 25 20 15 10 5 0 Snow Site 27 S G 65 60 55 50 ~~~~~r----ir------; .. ~HH .. .-~.---~ .. --~1---~.. 45 40 35 30 25 20 15 10 5 ~~~~~~~~~~~~~~~~~~~~~~~~~~~ 0 6 11 16 21 26 31 36 41 46 Sequential Sample Points Figure 30. Snow depths at sequential sample points for snow site 27 . 57 Snow Site 28 65 65 60 60 55 55 50 50 45 45 Snow Depth 40 40 (i nches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 21 26 Sequential Sample Points Figure 31. Snow depths at sequential sample poin s for snow site 28 . 65 60 55 50 45 Srow Depth 40 {i nc hes ) 35 30 25 20 15 10 5 0 SrowSite 29 58 65 60 55 50 45 40 35 ~---;~HHHH~~~ ...... ~~~--~~~~._ ...... r-------{ 30 25 20 15 10 5 ~~~~~~~~ .. ~~~~~~~~~~ .. ~~~~~~~~0 6 11 16 21 26 31 36 41 46 5 1 56 Sequ ential Sample Points Figure 32. Snow depths at sequential sample points for snow site 29 . Snow Depth (i nches) 65 60 55 50 45 40 35 30 25 20 15 10 5 0 SnowSite30 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 Sequential Sample Po ints Fig ure 33 . Snow depths at sequential sample points for snow site 0. 59 65 60 55 50 45 40 35 30 25 20 15 10 5 0 60 SnowSite31 65 65 60 60 55 55 50 50 45 45 Snow Depth 40 40 (i nc hes) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 6 11 16 Sequential Sample Po ints Figure 34. Snow depths at sequential sample points for snow site 31 . ~ If 0 Mile a 5 (,--= -! · .. fo Kllometera 10 , Figu r e 35. Merch 1885 anow depth bird trenaecta In the middle 8ual tne River blain, Aluke . · .. ·····~. 0'1 ....... 62 Bird Transect 1 65 65 60 60 55 55 50 50 45 45 Sro,y 40 40 Depth 35 35 (i nches) 30 30 25 25 20 20 15 15 10 :o 5 5 0 0 0845 0915 0945 1015 1045 1115 1145 1215 1245 1315 1345 1415 1445 1515 Sequential 15 Minute Interval Sample Po ints Figure 36. Snow depths at sequential 15 minute intervals for bird transect 1. 65 60 55 50 45 Sra.v 40 Depth 35 (i nches) 30 25 20 15 10 5 0 0830 0900 0930 Bird Transect 2 1000 1030 1100 1130 1200 1245 1315 Sequential 15 Minute Interval Sam pie Po ints 1345 1415 63 65 60 . 55 50 45 40 35 30 25 20 15 10 5 0 144 5 Figure 37 . Snow depths at sequential 15 minute intervals for bird transect 2. 64 Bird T ransec:t 3 65 f" 60 60 55 55 50 50 45 45 Srow 40 40 Depth (inches) 35 35 30 30 25 25 20 20 15 15 10 10 5 5 0 0 0845 0915 0945 1015 1045 1115 1145 1215 1245 1315 1345 1415 1445 1515 Seque ntial 15 Minute Interval Sample Points Figure 38. Snow depths at sequential 15 minute intervals for bird transect 3. Bird Transect 4 65 65 60 60 55 55 50 50 45 45 Srow 40 40 Depth 35 35 (inches) 30 30 25 25 20 20 15 15 10 10 5 5 0 0 0845 0915 0945 1015 1045 1115 1145 1215 1245 1315 Sequential 15 Minute Interval Sam pie Points Figure 39. Snow depths at sequential 15 minute intervals for bird transect 4 . 66 Bird Transect 5 65 65 60 60 55 55 50 50 45 45 SroiN 40 40 Depth 35 35 (inche s ) 30 "30 25 25 20 20 15 15 10 10 5 5 0 0 1115 1145 1215 1245 1315 1345 1415 1445 1515 Sequential 15 Minute Interval Sam pie Po ints Figure 40 . Snow depths at sequential 15 minute intervals for bird transect 5. 67 Bird Transect 6 65 65 60 60 55 55 50 50 45 45 Srow 40 40 Depth 35 35 (inches) 30 30 25 25 20 20 15 15 10 10 5 5 0 0 1115 1145 1215 1245 1315 1345 1415 1445 1515 1545 1615 Sequential15 Minute Interval Sample Po in ts Figure 41 . Snow depths at sequential 15 minute intervals for bird transect 6. 68 65 Jay Creek Draine 60 55 50 45 40 SrowDepth 35 (i nches) 30 0 0 0 25 20 0 15 0 10 5 0 2 3 4 14 S ites Figure 42. Comparison of snow depths for sites in the Jay Creek drainage. 69 65 Coal Creek Dralnage 60 55 50 45 40 SrowDepth 35 (inches) 30 0 25 0 0 0 0 20 15 10 5 0 5 6 7 8 9 Sites Figure 43. Comparison of snow depths for sites in the Coal Creek drainage . 70 65 Watana Creek Drainage 60 55 50 45 0 40 Snow Depth 35 (inches) 30 0 25 0 0 20 15 10 5 0 20 21 22 17 Sites Figure 44. Comparison of snow depths for s ites in the Watana Creek drainage . 71 65 ClarWTsusena Creek Drainage 60 55 50 45 0 40 Snow Depth 35 (i nches) 0 30 0 25 20 15 10 5 0 23 24 25 Sites Figure 45. Comp arison of snow depths for sites in the Clark/Tsusena Creek drainase 65 60 55 50 45 40 0 Snow Depth 35 (i nches) 30 25 20 15 10 5 0 28 Devil Creek Drainage 0 27 S ites 0 26 ...,..., ',{ Figure 46 . Compari s"O n of snow depths for sites in the Devil Creek drainage. 65 60 55 50 45 SrowDeplh· 40 (inches) 35 30 25 20 15 10 5 0 Basin-Wide Elevational Comparison 35 34 33 32 31 30 29 28 28 27 27 26 26 26 25 25 25 25 25 25 23 23 22 22 22 20 18 1 7 16 1 5 11 75 50 oo 5o oo oo 40 eo oo 50 50 90 5o oo 80 5o 50 25 oo oo go 80 5o oo oo 5o 62 2s oo 1 o 1 o Elevation 73 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Figure 47. Comparis on of snow depths and decreasing elevations for 31 snow site.s .