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HomeMy WebLinkAboutAPA3422SUSITNA HYDROELECTRIC PROJECT FEDERAL ENERGY REGULATORY COMMISSION PROJECT No. 7114 MOOSE FOOD HABITS AND NUTRITIONAL QUALITY FORAGE IN THE MIDDLE SUSITNA P.IVER BASIN, ALASKA PREPARED BY UNDER CONTRACT TO [}{]~~~~=(g@~@©@ SUSITNA JOINT VENTURE FINAL REPORT MAY 1986 DOCUMENT No. 3-i22 Alaska Power Authority =======.1 SUSl:TIIA BYDROBLBC'l'RIC PROJBC!' Dacu•nt No. JU2 Suaitn. fila No. •.3.3.2 MOOSB POOD HABITS ARD RDTRITIOBAL QUALI~ PORAGB I. T11B IIIDDLB SUSITM RIVD BASI., AUSD Report by LGL Alaska Research Associates, Inc. William D. Steigers, Jr., LGL Earl F. Becker, ADF&G Under Contract to Harza-Ebasco Susitna Joint Venture Prepared for Alaska Power Authority Final Report May 1986 l IIOfiCB AllY QOBS'fiOIIS OR CDMfii!S COIICDIIIIG 'fillS UPOH SBOOLD BB DIUC'l'BD TO '!1m ALASD KMU AO'fllORI'l'Y SOSI'ftiA PROJBCr OPPICB IN'.IRDJC:!'riCII . • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 1 SBCTtON I-STUDIES •••••••••••••••••••••••••••••••••••••••••••••••• ~ 3 Winter Food Habits of Moose in the Middle SUsitna River Basin, Ala.ska......................................................... 3 ()Ja).ity of Winter Moose Forage in the Middle SUsitna River Basin 1 Al.a.sJca. • •. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 25 SECTION II-MODEL INPOTS ••••••••••••••••••••••••••••••••••••••••••• 48 fblthly Diet Crap?sitial, Digestibility, and Crude Protein ••• ~. 48 Mbnthly Diet SUbstitution •••••••••••••••••••••••••••••••••••••• 51 Literature Cited ••••••••••••••••••••••••••••••••••••••••••••••• 53 .. . I 1 lr l~ I r 1 IWDODUCTIOJ The propo .. d Suaitu Hydroelectric Project in the aidclle SoaitDa River basin of southcentral Alaska vould peraanently re.ove habitat naad by ~interiDI aoose. In early 1983 the Alaska Power Authority -de a decision to pursue assesaent of proposed project illpacts on aoose habitat by developin& eatiaates of loss of nutritional carryiD& c .apacity. Jutritional carryin& capacity can be defined aa the size of a healthy and productive population that the ava ~lable food resources of a unit of land can .. iDtaiD without pe~ently desradiD& habitat quality. A ruainant co.puter st.ulation .odel specific to aoose beiD& developed by the Alaska Departaeot of Fish and Game. (ADF&G~ vas to be used to develop nutritional carryins capacity estimates. This aodel intesTates nutritional requireaents of the animal with those forase nutrients supplied by the habitat. F..,rase nutrients senerally considered most important (limiting) to ruminants are energy and nitrogen. For rwa.inants such as •oose, digestibility of winter forages is also important. The ruminant s timulation model was developed and tested by ADF&G on the Kenai Pen.insula. Specific information was required to adapt the model to predict carrying capacity for the Susitna project area. This report is dividr.d into 2 sections. Section 1 cloe181Dts tile results of 2 studies designed to provide information specific to project area. In the first study, winter food habits of aooH middle Susitna River basin were determined froa fecal pellet The second study docuaents seasonal nutritional digestibility of those plant species eaten by moose durtaa ~~~ .-.-&."'"'-'- results of these 2 studies have been written in a for.at I [ ~ I r I ~ r I. !- 1 2 their eubaissloa for journal publication, ud are pre .. nted 1a that for.at. References to figures, tables, and literature cltatioaa witbiD the tezt of each study in Section I are specific to the respective study only. Section II of this report co.bines and ~rues the reeults of the 2 previous studies into .. aninaful inputs to the carrytna capacity .odel. This section also provides justification, ratioual, and reco..endationa for certain related aasu.ptions that vill be .ade 1D the carryina capacity 80del st.ulation runs. References to figures, tables, and literature citations within Section II are specific to this section only. SECTION I b I -............. "' ........ -............... ~. __..._ .... ~.._ .... "' ... --~--·-----.. -...... -..................... ---· ·--... ----------------.... -...... -..... ... r J. I r r r r Dr. Villi~ D. Steiaera. Jr. SR.D. lox 9038-A Pabler. M. 99645 (907) 745-6218 4 JlUDDlna Beacl: ViDter Moose Pood Habits 1D Alaska • Stei&era et al. WINTER FOOD BAIITS OF MOOSE IN THE MIDDLE SUS I TNA RIVER BASIN , ALASL\ 1 VUliaa D. Stetaera, Jr.. LGL Alaska lleaearch Aasociatea, IDe •• 505 v. llor~bem Lip~a llYd. • Suite 201, ADchorqe, M. 99503 VayDa L. lleaeliD, Alaska Depart.ent of Fish aDd ea.e. 1300 Coll•a• lload, Fairbanka, M. 99701 Earl P. Becker, Abaka Depart.ent of Fish and Gaae, 333 llaspberry Road, Anchorase. Al 99502 2 Charles L. Elliott, University of Alaska, Fai.rbanks, Fairbanks, Al 99701 3 Ja.es G. MacCracken, • University of Alaska, Fairbanks, Agricultural and Forestry Exper~nt Station, 533 E. Pireweed, Palaer, Ak 99645 Abstract: Winter food habits of .oose (Alces alces gigas) in the middle Suaitna lliver basin of southcentral Alaska were determined froa ~crohi.stological analysis of fecal pellets. Pellet saaples were collected froa line transects and analyzed separately for 9 areas witbi.n 1 Present address: Sll.D. Box 9038-A, Palmer, AK 99645 2 Present address: University of ~entuclty, Depart•ent of Biology, llidmond, n 40475 3 P ~eaent address: USDA Pacific Northwest Research Station, Institute of Northern Forestry, 308 Tanana, Fairbanks, Ak 99775-5500 ------------ Steiaers at al. 5 dla study area. Willow (Salix) vas the doainant co.pooent 1D fecal .-plas. naraaiDI 72% for all areu sud raaaiaa fro. 40-87%. Ieala birch (Betula slandulosa) averqed 11% for all areas (ranae 3-16%). MoulltaiD craaberry (Vacciniua vitie-idaea) vas bishest at 2 veatera sites (27% ad 41%) but vas relatively low in other areafl. Other species vere aiaor co.poaants of fecal a.-plea. Regioaal abundance ad diatributioa of willow appeared to 1Dfluence diet composition. We vere UD&ble to calibrate fecal pallet aJUllysis by differential in vitro diseatioo ad aicrohistolosical fras-ent identificatioa of residue for tbe .. jor dietary COIIpODenta. Accuracy 8Dd reliability of data 1s 1D question whenever the aicrohistolosical techDique is used. ltEY WORDS: Moose. Alces alee& 1!1.!!• Susitna, soutbcentral Alaska, winter, food habits, diet, forase, willow, Salix, in yitro • disestibility, IVDDM. Several studies on .ooae and their h a bitat 1D the aiddle Susitua lliver basin iaplieated woody browse species as the aajor coapon.ent of vinter diets . McKendrick et al. (1982) reported that willows were observed to be the most heavily browsed species in all vesetation stands sampled. Resin birch shrub ca.aunities vere noted to have received aoderate use, while only individual American green alder (Alnus crispa) plants appeared to be heavily browsed (McKendrick et al. 1982). Ballard et al. (1982) suggested that distribution of willow stronsly influenced seasonal distribution of aoose , and that willow distribution was useful in deterlliniDI the iaportace of habitats to moose populations. Steisers et al. (1983) reported tvis utilization by aoose in 9 .... ~......_-~~..: .... ~ ......... _~----~~ ..... -.......... ~---..................................... ~" h .... h 2 > .................... ~ .. ..._ ...... _ .. _ ... ,... ... _____ ..... ____ • _____ ~ •• r ~ r I r t::, Stetaen et al. 7 STUDY AliA The study are" vas located in the aiddle Susitna liver basin in soutbcentral Alaska (Fig. 1). Generally, the area vas a broad U-sbaped valley occupied by the Susitna liver. N\nlerous tributaries drained into the river along its course. liver elevations ranged froa about 270 a on the western end of the study area to appro:xiaately 750 • on the east. Topography has been strongly influenced by glacial action and associated river and stream erosion. Extensive sedt.entary terraces perched above the river channel were appro:xiaately 61Q-760 a in elevation, and aade up a aajority of the study area. The specific areas froa which saaples were collected generally bordered and paralleled the SuiJitna liver for appro:xiaately 120 km along its east-vest orientation. Nuae.rous plant c~nities characteristic of the northern boreal forest occurred in the study areli . R.A. Kreig and Associates, Inc. mapped 92 vegetation types to level~ 11.1 and IV of Viereck and Dyrness (1980; 1982 revision). Distribution of plant communities was strongly influenced by site topography, soils, and moisture regimes. ~ Feltleaf willow (Salix alaxenais) was the predoainant shrub growing along riverine and st~e-riparian zones and on disturbed sites. Steep, well-drained river channel slopes were dominated by coar~nities of aixed paper birch (Betula papyrifera)-vhite spruce (Picea glauca) forests and open coniferous spruce forests. Terraces at higher elevations above the river were primarily shrub ca..unities dominated by resin birch on the drier sites, with white spruce forests on moderately drained slopes, and black spruce (Picea aariana) forests on wetter, poorly drained sites. Willows, priaarily diamondleaf willow (Salix pulchra), grayleaf willow <!· glauca), and Richardson willow (!. lanata), I r Stdpn et al. 8 doa!Dat.. tbe abnab c• •altiea ill wetter altea 011 uplaDd alopaa and lntemixad wltb raalD blrcb 1D coulferoua foraata. AlplDe veaatation type a occurred at tbe blpeat elnationa. METHODS AID MAt'DlALS WlDter fecal pelleta of 800ae vere collected alona 32 line tranaecta aa part of ~ber atudy (Bela and Mayer 1985) durlna early apriq (late April tbroqb early Kay) 1983 (Pia. 1). At each of 9 area•, 2 non-raDdoaly placed parallel tranaecta approxiaately 100 a apart on either or botb tbe north-and aouth-facina elope• of tbe Suaitna River chaDDel vere walked by observers. Twenty-eight transect• at 8 aites extended froa the up~and terraces downalope to the Suaitna River or aajor tributary. Four transects at 1 site (Fog Creek) extended generally dovnalope parallel to a tributary located on a terrace above the Susitna River. Transects ranged in length from 1.2-1.6 ka. Fecal pelleta vere collected opportunistically froa atop melting snov along the tranaects to ensure they bad been reliably deposited during the winter aonths. Four pellets vere randoaly collected froa each pellet group. Pellet samples vere composited within each of the 9 areas. Because pellets vere collected opportunistically, total sa.ple size in the ca.posite varied UlOng areas. Fec.al saaples vere forced-air oven-dried at 60 C for 48 hours, then ground once through a Wiley aill using a 1 ma screen (Bolecbek and Gross 1982). For each area, subsample~ vere taken equal to one-half (1 extra if a fraction) of the total nu.ber of saaples in ea~b coaposite. Microbbtological exaaination vas used to identif~ food it:eas in fecal pelleta (Sr arks and Kalecbeclt 1968, Free et al. 1970, Dearden et al. 1975). This procedure bas aany advantages as discussed by Holecbek I ,. ~ L r I ., r I I. • 1 D$ tla• 'llla1c1a -coaaW.rM to pro.Ua uaquate HllpliDI iau n e lty f• ~-.,.cia ill the fecal pelleta. Twaty •alld aicroacope f:l..U. -.a reM at 12Sa ae ucla alida (Bolacbelt aD4 Groaa 1912) • A •al.U fleU U4 to coataia at laut 2 dlacanibla pl.at fr ..... ta. A 4Uceniltla f~t fr..-nt wu dafi.Dad by Jobnaoa at al. (1913) u a fr ..... t "b.Yilal at laut 2 diatiDct aaatoaical characteriatica, aacb .. alllca bodiaa. tticJac.ea • or ata.at .. ". Data v.. recorded .. fraqaeDCy of occurraac:a of diacarllible fr ..... ta 1D a field 1D relation to the towl .....,_r of fielda r.... Thia baa bean calle4 the "percent frequaDCJ Uditioa" procedure by Bolecbelt aud Groas (1982). aDd ... statiatically evaluated 1D their study. Only the frequency of occurrence of diaceroible fragaents in the aicroscope field vere recorded. Discernible frag.ents i~cluded both known and unknown species. Ubiquitous fr..-nts of plants such as xylea, protoxylea, and phloea vere not recorded. All pl.ata vere identified to species vhen technically po_ssible. Forbs and graainoids vere identified and cm~piled as life form categories. Every effort vas aade to identify to genera and species all unknown plant frapents that .ade up a substantial proportion of the saaple composition. Viereck and Little (1972) was used as the vernacular authority for scientific and com.on names of plant species. To calibrate for possible differential digestion of the major plant species found in the fecal samples, in vitro digestible dry matter (IVDDK) was determined ·for plant species alone and in combination as test diets. Currt:nt annual growth tvig11 of willow, resin birch, wholE 80Ulltain cranberry plants (twigs and l eaves), and .ass {pri .. rily 10 II' s .,.) wen eolleet.. Rrt.aa October fraa tbe at1MIJ U\._, fore .. -etr o.ea-4ri.. fer 41 haara at 60 C. ADd 1~,_• ODCa tbroap a vtley ld.ll ataa a 1 -acreea. For th•~• aaly ... , 60:40 villow vu c ; aaacl af arouDII carreat aamaal IT'-~h twiaa of clir.-oDclleaf willow ADd faltluf willow, reapactivaly, in a 60~41:! ratio ~ry weilbt atstura. Pba teat cliau ucb co.priaacl of 60:40 willow, raaiD birch, .ountaill ernbarry. ad .,.. wn praparacl. Lavela for each foraae ill the cliat ldstaraa raJIIacl over tba apprmd.aate percentaaea obeervacl fraa tba fecal pallet 8aalyaia. Diet proportions ware vaiabad uataa a Mettler -4 electronic balance to the neareat 10 g. IVDDM vas deterained uataa the •tbod of Tilley and Terry (1963) as .odified by Goeriq and Va Sout (1970). IVDDI trials vere run ~n triplicate udng bovtae ~ inoculua obtat ned froa a -ture Holstein dairy cow fed broae (lro.us) hay and dairy ration. All IVDDM analyses vere run concurrently fro. the .... inoculua source, and the data expressed as a percent of digested d!"J -tter. Residue froa each replicate of the IVDDM trials for the 5 test diets vere analyzed for dietary composition using the aicrohistological technique . Methods followe d those previously described except 5 slides vere read per residue saaple. The saae observer and reference slides vere used for both the fecal and residue analysis. Neither coaposition or proportion$ of plant species in the IVDDM residue vere known to the technical observer conducting the microhistological analysis. RESULTS Fecal Analysis A total of 199 fecal aaaple s were collected from pellet groups along transects at the 9 areas . 1\lenty-six samples were collected from r.-; .... , .. ,.,, .. ---~~ ................. .., ... ---.. ~---......................... _ ..... ~ ........ -................................. _ ......................... _... -·-..__ ........................... _ ....................... 0 : .. . . r I· i Stet.aen et al. 11 0..11 Creek, 9 froa T.uaeaa Creak, 31 froa Foa Creak, 33 froa Vatana Creak. 14 froa Vataaa Slide, 14 froa Caaaie Creek, 23 froa loaina Creak, 11 froa Clarence Creek, and 38 froa O.hetna lliver trUUiecta (Fig •. 1). A total of 102 aubeamples were prepared froa the fecal sa.plea. Analysis of the winter .fecal s-.1lea shoved that willow vu the doainant coaponent for all areas sampled in the aiddle Susitaa lliver .· . basin (Table 1). Epideraal tricha.es characteristic of the genera could not be used to distinguish a.ong individual species of villov using the aicrohiatol@lical tecbnique. Baaed on percent dry weight COIIpOaition of identified frac-nta, villov ranged froa a high of 87% at the WataDa Slide area to a low of 401 at the Tauaena Creek area. Vith.in the 7 areas in the eastern half of the study area bordering the Suaitna llivar (Watana Creek to Oshetna River), percent coaposition of willow vas 771. These eastern transects generally traversed a greater proportion of upland benches and coniferous forests where willow forage biomass vas higher than in the deciduous forests com.on in the western half of the study area (:>evil Creek to Tausena Creek) (Beeker and Steiger& 1986). Fecal c0111position of willow vas lowest in the western half where it averag~d 461 froa the 2 areu (Table 1). Coaposition of resin birch in fecal saaples vas 111 for all areaa, ranging froa 3-161 (Table 1). Excluding the lowest value at the Tsuaena Creek area (3%), resin birch coaposed a fairly consistent but .aderately low percentage of fecal samples over the entire study area. Fecal composition of 110untain cranberry was greatest in the 2 western areas (Table 1). Forty-one percent of the fecal samples collected at the Tsusena Creek area were coaposed of .auntain cranberry. An increaaed ca~~ponent of mountain cranberry at the 2 western areas ~ ... -~· ...... ~~-------....... -----~---·-·· ·-·. -· ---·-----.... -----------· ----· ...... . Steiaera et al. 12 ai&ht have been related to the decreaaed availability of villov (Becker and Steiaera 1986). Percent co.position vas low for all eastern areas except Cassie Creek and ~sina Creek, which had 11% and 1S%, respectively (Table 1). Similar to .ountain cranberry, percent coapositi o:t of araaiDoids vas also greater at the 2 western areas (Table 1). Preauaably, .oose were foraging .ore at the dwarf shrub and ground layer vegetation levels in the western part of the study area where deciduous forests were .ore preda.inant and the pd ... ry food source of willow was less abundant (Becker and Steigers 1986). Percent c011position of sr~ids vas relatively low in the fecal samples at all western aceas (Table 1). Paper birch was found to be present in fecal samples only at the Watana Creek area (Table 1). Quaking "spen (Popu.lus tremuloides) alder, lichens, and forbs and other shrubs were IDinor components in fer.al samples throughout the study area (Table l). Dietary Calibration In the preliminary analysis of the fecal samples, aoss was initially identified as both a consistent and relatively important coaponent . Proportions of moss ranged froa 12-23% over the 9 a reas, averaging 18% for all areas . Prevalence of moss in fecal saaples was not easily explained. Though it was the doiDioant ground-layer plant species in the study area (Steiger& et al. 1983), i t was not considered to be .oose forage. Because the dwarf shrub mountain cranberry grew interspersed with the aoss, it was conjectured that moss might have been inadvertently conauaed in the process of foraging for mountain cranberry. Field observations of 110untain cranberry forased from craters dug in the snow by moose !ended support for this argument. r l~ r -I, Steiaers et al. 13 However. aosaes were reported to be "coapletely indiaestible" • biably fraa-ented, and easily identified in aicrobistoloaical analysis by Dearden et al. (1975). Thus, calibration of differential diaestibility, frag.entation, and fragaent identification rate vas undertaken to prevent overestiaatioo of aosses and underestiaatioo of other foraaea in o•J r data. Results of in vitro digestion shoved aountain cranberry vas the aost nighly " ~estible species. whereas aoss vas the lowest (Table 2) • IVD~ for the 60:40 willow aixture (34.3%) vas close to the predicted IVDDM fro. proportiooalized individual values for dia.ondleaf willow and feltleaf willow (33 .9%) (Table 2). IVDDH of .ass (20.3%) vas substantially higher than the "completely indigestible" of Dearden et al. (1975). IVDDM results closely paralleled those reported for the saae study area by Steigers et al. (1986) using moose rumen fluid. We were unable to calibrate results of the fecal sample aicrohistological analysis because reliable linear regression Lelationships could not be developed between true proportions and proportions resulting from analysis of IVDDM resi due of the test diets (Table 3). High variation between true proportions and residue proportions, high variation a.ang residue replt cations, and aisidentification of species in IVDDK residues were the primary causes. Differences ranging to 67% IVDDH between true and individual replication proportions of residue were found in several test diets. Microhistological analysis of undigested fractions of the test diets yielded siailarly variable results for many the same rea3ons (Table 3). It vas learned during the course of the microh.istologi cal analysis of IVDDM residue, however, that what had originally been identified as -r r I L I I r r I . I I Steiaera et al. 14 .oases were ill fact stea structures (laticifers) of vUlova. Furthe1110re. it vas learned that none of the species unde~ study were exeapt froa aisidentification us ina the aicrohistel~ical technique. Experiaentally deterained diaestibility of the abed teat diets (deteilllined IVDI»>) was found to be veJY siailar to the au.aation of digestibilities of the coaponent diet iteaa veiahted by proportion (predicted IVDI»>) (Table 3). There did not appear to be aeneral trencla between the 2 values as a result of changina proportions of the species in the test diets. DISCUSSION This study has shown that willows were the -j or ca.ponent of winter diets of aoose in the study area. The technique used to identify dietary fragments did not allow separation of the willows by species . However, other studies have shown that the species of willows that are doainant components of the vegetation ca.munities of the study area all contribute to the forage resource. Studies conducted by Steiger& et al. (1983) documented that diamondleaf willow, grayleaf willow, Richardson willow, and feltleaf willow were the aost coamon willows in vegetation types where they occurred; diamondleaf willow was the aost common of the willows. Diamondleaf willow bad the highest current annual growth bi0118ss of all willows in the study area (Becker and Steiger& 1986). Other species of willows also g r ow in the study area, but they generally uke up a small proportion of the willow bi01118ss (Becker and Steiger& 1986). Stdgers et al. (1983) reported that individual species of willows were browsed by aoose in approximate relative proportion to their stem density. r r ' r ,. I I . Steiaera et al. 15 Pallets collected aloq line traoaects passed throuah uu.erous different ••aetatioo typea aDd alooa a contJ.ouua of elnatlooal &radiants. There vas no deflDite .. ana to deteraille exactly the area where the forage vbich vas the source of the pellets vaa conaU8ed. Pellet sa.plea vera grouped by geographic area priaarUy to represent possible •ariati.cm in diets alooa the east-vest orientation of the Susitna lliYer draiDage withlD the defined study area boundaries. The results indicate atailar diets throughout the eastern half of the study area. with willow predoainatiDg. The western half of the study area had less willow bioaass in the uoderat~ry layer in the rher canyon (Becker and Steiger& 1986). and this vas reflected 1D the fecal analyses. ReslD birch vas a c~n .shrub species in the study area. It vas not considered a preferred forage species for .aoae. and vas utilized only lightly in relation to its availability (Steigers et ~Jl. 1983). Availability of forage bioaass of reslD birch vas not a factor liaiting its intake by aoose (Becker and Steiger& 1986). However. it appears that .oose will voluntarily consu.e resin birch up to approxiaately 15% of the diet. Murie (1944) reported that dwarf birch (Betula ~) vas regularly browsed by .aose in Denali National Park. Tbe frequency of occurrence of .ountain cranberry in fecal pellets of moose vas high in the Devil Creek and Tsusena Creek areas. Moose say have been expending .ore effort locating and consuming mountain cranberry growing at the dwarf shrub layer in the western part of the study area where willow vas leas abundant. While tracking moose through snow near the aouth of Tsuaena Creek in March. it vas observed that mountain cranberry vaa exposed directly beneath the canopies of spruce trees while between tree canopies it vas covered by snow approaching 75 r Steiaera et al. ca deep. Tracb led fr• tree to tree as .oou were appareatly feediD& OD the expoaecl .OUDtaiD craberry aDd Other &rounci-layer Ve&etatiOD. Lelleache aod Davis ( 1973) described staUar crateriD& by .oose for .ouataia craaberry oa the l.eaai Peaiaaula. Oo a depleted l.eaai Peainaula viater ranae, .ouataia cranberry co.posed 51% of observed bite couats (Lelleache aDd Davia 1973). Deep snow cover persists throuabout .ost of the viater in the study area, aakilla .ouutain craberTJ, licheDS, and other arouacl-layer plants of li.aited availab: lity as 800 .. forqe. Mountaill craberry 1a olll.y coDSidered li.aited to a .. xi•• of 20% of the averaae .ooae diet iD the study area duria& the period January tbrouah April iD winters of li&bt or average SDovfall and duria& the period Dece.ber through April in viaters with e.arly, c;Jeep saovfall. Paper birch as forage for .oose occurs in the study area prt.arily as adventitious basal shoots froa matuTe tne&, and to a lesser extent in disturbed areas such as stre_uabanka and slides (Steigers et al. 1986). ObseTVations of only li&bt brovsiag pressure on paper birch throughout the study area support the c onclusion of low dietary CO!!IlPOsition foun d iD this study. However, it i s uo1coovn whether this is a result of fever lWIIbers of .oose utiliziag the steeper canyon slopes where paper birch arovs, or the possibility that the paper birch foraae available to 1110ose is in ao.e vay leas palatable than regrowth available in other areas such as the Kenai Peninsula. Higher phenolitic resin content in adventitious basal sprouts than in mature tree crown twigs (Bryant 1981) may have inhibitory effects on digestibility of paper birch (Reisenboover et al• 1985), thus affecting its rate of ingestion as forage by 800Se (Steigers et al. 1986). Paper birch as a dietary Of • I L r I~ r r Steiaera et al. 17 e.,cmnt in the study area is ltaited priaarily by availability of foraae bia.aaa. Qaaktq aapen occurred 1.n.frequently in the aiddle SuaitDa J.iver basin. Alder vas a relatively ea..on species, but observations durtaa previous studies (Steiger• et al. 1983, Steigers and Be~ 1984) doCU8ented that 800se avoided br:O'.IIiing alders growing in dense ataads. Certain individual alder plants, especially those with nev tvia regrowth following previous browsing and those growing on recently disturbed sites vitb a high villow:alder ratio, were occasionally browsed. The inability to accurately and reliably eatt.ate true proportiona in teat diets using the aicrobistological technique throws so.e doubt on the validity and accuracy of the original analysis of fecal sa.plea. OD one band, ve aight partially explain the decrease in willow and increase in .auntain cranberry at the-2 western areas by aisidentification of species. On the other band, other evidence on differential regional forage availability exists (Becker and Steigers 1986) that augesta there are viable reasons to support the results as presented. In our studies the technical observer vas not informed of the species coaposition of the test diets; the results would likely have been leas variable bad the technici an been infor.e-J . The technician did, however, use the saae reference slide collection and. knev they were winter teat diets for .ooae. Obviously, •iaidentification of identifying characteristics and the inherent difficulty in identifying fragaents froa woody tissue were the major proble.s encountered using the technique. lesson learned though the analysis of IVDDH Probably the greatest residue vas that the microhistological technique should be used only to obtain probable I I I f I I ~ r Steqera at al • 18 .,.ci•• co.poeitioa iD diete aad aad aanerally broad r..... of percent ca.poeitioe. Tbia tecbaiqae is aot a .. fficiently reliable tool to use for tietar, aDalyaia other thaD to obtain aroaa eatiaatea of c011positio1l. With the above pidelinea iD aiDd, we cu dOClDII!nt that the doai.Dant co.pooent of .ooae villter dieu iD the aiddle SaaitDa ti'Wer baa in ia villo.r. Darin& aid-ancl late-winter (Dece.ber through April) , willow -y c011priH ap to 901 of the diet. A aut.. of 15-201 of the winter diet ia reain birch. Mountain crauberry ud gTaai.Doida are uaually covered by auow duri1lg winter vben forage availability beco.es liaitiq; their use ia probably governed by accessibility durin& the aid-and late-winter critical periods. Other species are aillor winter dietary coapouents. LITERATURE CITED Ballard, W.B., C.L. Gardner, J.B. Westlund, and J.R. Dau. 198 2. Moose -upstreaa, Phase I. Vol. Ill in: Susitna Hydroelectr ic Project big game studies. Alaska Dep. Fish and Game for Alaska Power Authority Susitna Hydroelec tric Project. 119pp. Becker, E.F., and V.D. Steigers, Jr . 1986. Moose forage iOIIUlBs in the aiddle Susitna River basin, Alaska. Alaska Dep. Fish and Game for the Alaska Power Authority Susitna Hydroelectric Proje&r. Bryant, J.P. 1981. Pbytocbeaical deterrence of sno.rsboe iui!'"~ bra.r•ing by adventitious shoots for four Alaskan trees. Sci. 213:889-89~. Dearden, B.L., R.E. Pegau, and R.M. Hansen. 1975. Precision of microbistological estiaates of rWDinant food habits. J. Vildl. Manage. 39:402-407. r I !' Stetaers et al. Free, J.C., a.M. Baa8eD, and P.L. St.a. 1970. of food plaats in feces of herbivores. 23:3Q0-302. 19 Eatt.atiq dry veipta J. laDle Kanaae. Goerina, B.l.., aad P.J. Van Soest. 1970. Foraae fiber analy•is. Apparatua t reaaents t procedures t and s~ applications. AaT. Handbook. lo. 379. U.S. Govt. Print. Off. 20pp. Bela, D., and P.V. Mayer. 1985. Plant phenoloc study. Univ. of Alaska, Aaric. and For. Exp. Sta. tor Alaska Power Authority Susitna Hydroelectric Project. 256pp. Holecbek., J.L., and B.D. Gross. 1982. Evaluation of calculation procedures for aicrohistoloaical analysis. Kana&•· 35:721-723. different J. llanl• M. Vavra, and R.D. Pieper. 1982. deteraination of range herbivore iets: Botanical coaposition a review. J. Ranae Manage. 35:309-315. Johnson, M.K., B. Wofford, and B.A. Pearson. 1983. Digestion and fragaentation: influence on herbivore diet analysis. J. Wildl. Manage. 47:877-879. LeResche, R.E., and J.L. Davis. 1973. .oose on the Kenai Peninsula, 37:279-287. laportance of nonbrovse foods to Alaska. J. Wildl. Manage • McKendrick., J., W. Collins, D. Bela, J. McMullen, and J. Koranda. 1982 . Plant ecoloiJ studies, Phase I. Univ. of Alaska, Agric. and For. Exp. Sta. for Alaska Power Authority Susitna Hydroelectric Project. 124pp. Murie, A. 1944. Ser. Bo. 5. The wolves of Mt. McKinley. 238pp. U.S. !~at. Park Ser. Fauna j f r I I I F I I• Stei&era et el. 20 leiaeaboower, K.L., L.A. lenecker, and L.E. KoraantiDi. 1985. Effecte of secondary .. tabolites fro. bal.aaa poplar aad paper birch on cellulose di& .. tiou. J. lange Mana&•· 38:37G-372. Sparlta, D.a., aDd J.C. llal.ecbeck.. 1968. Estiaating percentage !Jry vei&bta in diets usiug a aicroscopic technique. J. lange Manage. 21:264-265. Steigera, W.D., Jr., E.F. Becker, and W.L. legelin. 1986. Quality of winter .ooae fo:-age in the aiddle Susitua lliver basin, Alaska. Subaitted to J. Wildl. Kanase. , and D. Bela. 1984. Terrestrial prosr-1983 browse pilot study. Univ. of Alaska, Agric. and For. Exp. Sta. for Alaska Power Authority Susitna Hydroelectric Project. 341 pp. --· , J. G. MacCrack.en, J.D. McKendrick., and P. V. Mayer. 198:',. 1982 plant ecology studies. Univ. of Alaska, Agric. and Foi. Exp. Sta. for Alaska Power Authority Susitna Hyd roelectric Project. 288pp. Tilley, J.K.A., and R.A. Terry. 1963. A two-stage technique for the~ vitro digestion of forage crops. J. Br. Grassl. Soc. 18:104-111. Viereck., L.A. , and C. T. Dyrness. 1980. A prel:iJilinary class if icntion systea for vegetation of Alaska. USDA Forest Service, Pacific Northwest Fqr. and Range Exper. Sta., Gen. Tech . Rep. PNW-106. __ , and E.L. Little, Jr. 1972. Alaska trees and sb.rubs. Agric. Handbook. No. 410. USDA For. Ser. Washington, D.C. 265pp. 0 0 Mila a 10 10 ao Kllomatara -,- ao JO Plturo 1. Troftaoat laoatlona for oallaotlon of winter mao .. faoal pallata far the ••••• food' haltlta atudr. 1 Dewit Craall I TIUMftl Cr .. ll a-Watana Cr .. ll 4 Watana l llda I ,01 Craall e c ..... c'"" 7 Koafft a Craall t Clar~M• CrMII I Owtn a '""' N .... -1.-...._, Table 1. Percent dry wei1hta composition of winter fecal pellets of aooae for 9 areaa in the .tddle Suaitaa 11•er baain. Alaaka. Dietary Devil Tsuaena Watana Watana Fog Caaaie ltoaina Clarence Oahetna All Coaponent Creek Creek Creek Slide Creek Creek Creek Creek lliver area a Willow 49 40 71 87 80 80 69 84 80 72 Resin birch 10 3 14 7 9 7 10 9 16 11 Paper birch 4 1 Mountain cranberry 27 41 1 1 3 11 15 1 1 • Quaking aspen 5 1 1 Alder <1 <1 Lichen 1 <1 <1 Graminoid 12 14 2 3 5 <1 4 5 1 4 Forb & Other Shrub 2 2 3 3 3 2 2 3 2 2 a Due to rounding error. the dry weight may not total 1001 . r 23 dsiaa bov ine ru.en inoculua. I IVDDI I· Sped as -]( SD Dt..oudluf villov 39.8 a Peltleaf vtnov 28.0 a I 60:40 villov 34.3 1.3 I Resin birch 27 .8 0 .6 Mountain cranberry 44.2 1.6 r lk!l& 20.3 0 .8 a 1 in ~ replication i· I - Table 3. Percent dry veiaht coapoeition end lVDDK ueina bovine inoculua of 5 teet diete. Teet 60:40 Reein Mountain Deterained Predicted Diet Treatment villov birch cranberry Hose Alder Aepen lVDDM(SD) lVDDM(SD) 1 True proportion 70 10 19 1 0 0 33.9(0.1) 35.4 i Und i aeetad 85 10 n 0 5 0 x Dia .. ud (SD) 69(4. 7) 5(6.4) 26(1. 7) 0 0 0 2 True proportion 67 1 29 3 0 0 37.9(1.1) 36.7 i Undiaeeted 66 7 4 0 0 23 i Diaested(SD) 59 (1. 7) 3 (1. 0) 38(2.0) 0 0 0 3 True proportion 45 25 10 20 0 0 27.1(0.8) 30.9 i Undigeeted 63 34 3 0 0 0 x Digeated(SD) 66(5.1) 22(3.1) 6(7.4) 0 4 (3. 5) 2(4.0) 4 True proportion 86 6 1 7 0 0 34.4(0.6) 33.0 i Undigested 81 19 0 0 0 0 x Diaested(SD) 85(13.3) 9(8.2) 1(1.7) 0 5(4.0) 0 5 True proportion 25 15 50 10 0 0 33 .8(1.0) 36.9 x Undigested 59 21 20 0 0 0 N x Diges ted(SD) 72(17.3) 5(0.6) 17(13.5) 0 6(6.0) 0 .. .. r l I r r I I r QUALITY OF WINTER MOOSE FORAGE IN THE MIDDLE SUSITNA RIVER BASIN • ALASKA 25 r I· I ' r Dr. Wl118 D. swt~n.Jr. SR. 0. 8Dx 9038-A Pll..,. 1 II. 99645 (907) 745-6218 QtMLJTY Of WINTER tmSE f'OIMGE IN THE MIOOLE SUSITNA RIVER BASIN, AlASKA 26 Wi11i1m 0 . Stei91r1, Jr.,l LGl Alab Alarcla ~. Inc., 505 W. NDrthera litflb BMI., Stitt 201, AlcW., AK 99503 Earl F. Becbr,Alab O.pertnellttffiHendGeme, 333 Raspberrt~ Rold,~,AIC 99502 Wqne L Al9eli1,Al•b O.pertmenhffitbendGIIM, 1300Ce11. Ailed, FliriiMb,M.. 99701 AMACt: Nutriti4Nal14utlitv tf viAttr tong~~ of IROOII (~ elcet gi_gg) ia the nridllle SUiit• Riwr blsin of soutbcentnl Alesklwre tv~lueted for in vitro di4)8Stible drt~ IDittlr (IVOOM) 1M crllie protein content. Cur nAt enn•l grwtb tvi9' from 6 decidUDus henlwod Mrubl ..S 111¥11 and stems from 1 evergreen Mrf shrub wn collected durint 2 Yinter sample perieds. Then wa no tignificent diffeniCI in IVOOH beNeen sample periods for the 7tpeci• end no differeiCI in cnMie protein betwen sample periodss for en species excl udint peper birth. Crude pntei1 WI different between sample periods onlv for peper birth; differences wre probeblV artiflcts of semplint rather then ch10911 over time . TM dwrf thrub mountlin crenberrv (Ytceinium ~ !M) bed the highest IVDDH ~ut thel.....t cr .. protein conttnt of the 7 tbrube . IVDOH WI ..t different amont diamondlllf (Selix ukhr!), gravleet (~. glauce), and Richanllon (~. l!!!m) villCM, but feltleaf Yillw (~. alaxensis) vas substantiellv lover. IVDDH of both peper birch (Betula 1!!2!Jd..f!!t) end resin birth (1. tltndU)OM) WI lover than env of the Yi11CNS. Cr .. 1 Pr=nt address : SR. D. Box 9038-A, Pel mer, AK 99645. -.--,;.;,-. • •·r r I ('. I 1-, IR" l I 2 7 Steifenetll. ~· ..-t wsJitllest fir ,...,. ~rc• 1111111 relit Mrc•, lftllllwst fir .....Wn crullerrt- Die•Mieefvlllw W tM .....-,end trqleef _.Ric...,.._ Yi11w tM lwllt, era prWia Yll• tftM Ylllwl. A lifllific:lnt iiMrM c:ernlmea WI fould YheR IVOOM and crude ,.... Yll .. ..,.,.. compertd fw the •• apeci11 vttJria December ~r--0.82) c.ld Mlrch (r•-0.81) semple periods, end pooled ecross semple periods (r•-.75, excl..ting paper birch). KEY WORDS: Moole, Alc:a alca ti-'J!, SusitM, touthcentrel Alan, Yinter, autrittoR, fe,.., YilloY, S.lix. in vitA. cfi9estiMlity,IVOOM, crude protein, nitrc19'n. The cr•litv ef forage is •• importent c:ensideretion vhen eval..ting the c:epecitv et rlflglle,. to support Y11d1ife populations. Forege q•litg hll been commonly nportld in.,... tl cellular constituent. including fiber componentt end proteins. In~ or in Yitro dr!J mttt.r digestibility of plenb eaten by rumiMnt enimels ere elso usual11J reported . Sewrel wrken (Short 1!166, Brovn end Redcliffe 1971, Robbins et el. 1975, Robbins end Moen 1975, mc1emever et el. 1977) hive ettempted Yith limited s..:c:ess to correlate drv metter dite'tibiutv Yith venous !'utritive peremeten such a crt* protein, organic materiel, enervv digestion, era fiber, cellulose content , other crude fiber constituents, end minenls. t1Dit wran (MorriiOn 1954, Bissell end Strong 1955, Dietz 1970, mdemever 1974) consider dieterv era protein the most important plant nutrient because it provides nitn191n required by rumen microorgenitms for diteStion of cerbohvcfretet , end it essential for ruminant body meintenanc:e, grovth, reproduction, end lactation . Crude protein is often the most limiting nutrient for Yild ruminant., particularly during Yintar vhen wody plenta vhich ere lov in protein dominate the diet. DiteStibility is ebo en important determinant of the quality of forege . An evaluation of forage digestibilitv determines the amount of nutrient. utilized per unit consumed. Lowr digestibility hlrdwod b~ species often dominate Yild ruminant diets in Yintar . r [ . I I· I I j.~- r ~ r I 28 SwtnJ it .... 1Mt1 reporW H the ... itt_,,.,.. ia Al11a1 -diet.. Huch ef tM wrt ,..,...... ta Alelb Ml •• .. tllll KIMi PuiMu1t. uAelcbt end DIYia ( 1973) dllcriiiM the i! !H!l.....,fllilttl 1M MtritiHIJ eMlpia tl ,.,... eetea ~, Klnli ....... 01deme91r ( 1974) l1to ,.,.,..... the ntulta tlil met ditlltion If 3 brwae apecitl Ulld 11 the ICIDii . !! vitne4JIIti .. litt, avtrieatce•llt, HdiRinenl cempllitiea If Kenei fer• ,..,. deacribtd bt Olde•ver et aJ. (1917). F.,.. .-Jitt determi_. fnm r_. c:e•nb wa reported fw iM8rier AI..U .. " c..wv Mil Celdt < 1974). era pnteia cement of Yillwl wa daeribed for sita ia tntlrilr Alaska bv Milke ( 1 G69) end for both interior Alaska and tbe KeMi Pelli•al• ~ MlciHI ( 1979\ er• ,-. Hd i! Yitrt di911tilrilitv et npr~~~ltative diet. tl Kllli PeliRSult -wa-.crtMd ~ R19e1ineteJ. (1986). T,_. atudi11 provt-. apectfic nutritionel que1it9 i nforrnetion oa forage apeci11 UMd bv mooae in their napectiveanaa of atudv . Howver, similar information we not l\llilable for t• Rridd'le SUiitne River bllia vhere plant apecitt compolitiea end eeterv propertioM differed Yide1V from results reported from ot•r fje0graphiaa11y distant studies (Steiten et al. 1986). 1• primarv objective of tlris studv YtS to provide aree-s;.ec;fic informetion on the di4)1st" Jilitv end crude protein centent of Yinter forages used bv moose in the middle Susit• Rivr . besin of southcentrel Alasa. A teeondery objective YeS to determine if digestilrility end crude protein content of the dormant shrubs chtnged owr the coune of the '&linter . This information YeS required as pert of elarter program to estimate nutritional atrryi ng capacity of the study area. R.H. Polltnt of LGL Alesb Reteerch Associates, Inc . (LGL) tnd M.G . McDonald, T J.. Otto, end R.W. Catlt If tht Alan Deportment of Fiah end Geme (ADF&G) esliated Yith field collection of plant aemples. l.D . Aumiller of ADF&G end R.H. Pollard of LGL prepered samples for laboratory anal VIis . M.E. Hubbert end C.C. Schwrtz of ADf&G ere thanked for their assistance in conducting invitndi4)1StioneMlpes . R.l. fairbanks of Ham-Ebesco Susitna Joint Venture, R.G.B . Senner ef LGL, 1nd K.B. Schneider of ADf&G provided program support end critically evelueted the r ~' I· I I I I ~ ~· >· l· r I r.· ,.., r 29 Stet.,ers et 11. •HKript. fundint va prwided bv the Alesb Powr Authoritv ill support of the Sait• H4jllnllectric Pnject. STUDY AREA TM ,. ... ., trMwa1Gcettd iR tM middle SusitM Riwr bestft ia aevtlantnl Alab (fit. 1 ). Genenllv, the tree VIS I broad U-sbeped valleg eccupied bv the Susit• River . NumertiD trtbullri• dnined into tM riwr elong itt c:eurae . Riwr elewtiena nftgld frem ebevt 270 m ea tM wst to epproxintelg 750 m on the eest. Surrounding peeb of the Talbetne MDuntliM nnged tD 1,907 mIt the top ef Ht . Wetene . Topognpltt Ms been stronglv influenced bv glecill 1Ctio1 end ISIOCieted riwr and stream erosion. Extenstw tledi mentarv terraces perched eboYI the riYir cMnnelwre epproximetelv 610-760 min elevation, and made up • mejoritv of the ltudt .,.... Numerous plent communities cherecteristic of the northern boreal forest occurred ia tM studv eree . R.lt. Kreig and Associates, Inc . (Anchor•, Alesb) mapped 92 yegetetion tvpe~ to levels Ill and IY of Viereck and Dyrness ( 1980; 1982 revision). Distribution of plent eommunties VIS strongly influenced by site topographg, soils, and moisture regimes . feltleef viUw wa the predomi nent shrub grwi ng along ri peri an zones of streams and on disturbed sites. Steep, w11-dreined river channel slopes wre dominated by communities of mixed paper birch- vlrite spruce (Picee g!!!g) forestl and open coniferous spruce forestl. Terrecea It higher elevations above the river vere primarily shrub communities dominated bg resin birch on the drier sites, vith vhite spruce forests on moderately drained slopes, and bleck spruce (Picee meriane) forest~ on wtter sites. WillOVI, primarily diamondleef villw, grayleef villw, end Richardson villov, dominated the shrub communities in vetter sites on upland slope~ and intermixed vith resin birch in coniferous forests. Alpine vegetation types occurred at the highest elevations . r I I· r l r ~ I··· I 30 St~ttmetll . METIGDS saw•wnc:ellecWfrlli151iteslloAgt100t•lt'*'lfU.s.it• Riwr (fit-1) Mrill 2 vt•r _,..,.,....:Dice~ 11-13~ 1984 1M Mira 5-7~ 1985. Prier tJMNWge If..,.,.... .Wul» .,.a. ce•positiH eccurring tteecb lite~ tM ..-te IIIDple U. _._ Wit tn~Mnt If the .tudv ar~~~ ani lwlicopter ecce~~ coRiidentioRt tuidM ttlectieR fllf lit. lecetitRt . Ta,.t tlv"ult apedet wn ttmpled epportunimc:env It IICia lite durint the fint _.. peri .. t1 miXilllize tM aumber If lites npn~~nted Itt eecb specia. Stmpla II 7 •• species taw• tt be •jer c:alftlllneab tf 1n1101e diets il the stUikj aree (Steiten et al. 198~~ Steittn It 11 . 1986) wn etlltcted (T_.. 1 ). Shrub apecill tritiR111t Cllleded MriRt till DeceiRIIIr llnap1t peri4MI wre •• ttmpW1 if possl~1 vMI tM litl YIS reYiliW 4arill Hlrclt At eech lite ~ current ennual grovth Mts flf abrubs wn eli pped at the bud xele ac:er aM Mgged bv apecia. Onlv unbrowed Mgs wre co11ected 1 vhen plllible. Approximetelv 50-100 9 wt wight of plant material vas collectivelv accumulated from eecb species present at eecb site .turint eech ttmple period. Approximetelv f S M gs of diamondleef vi11W 1 tnvleef villw, tad Richenbon villov, 20 Mgs from resin lrircb 1 10 Mgs from peper lrircb, and 3 tvigs frot1 feltleef villov wre collected from eech shrub. One or more hendfulls of vbole mountaiR cnnberrv plants wre eli pped at ground level frem pib dug tbrougb the snov COYer . A wrialtle aumber of individual shrubs of each species wre sampled in order to meet the minimum wight pl at eech lite. Plent ttmpl• wre frozen until immediatelv prior to proceeting. S.mpltl wn OYtn- dried at 60 C for epproximetelv 72 hours . Dried leaves and other litter wre rernowd from the Mgs of ell species except mountain cranberry, Yhich is a dYarf evergreen shrub thet retains ib 1eeYel durint vinter. Samples wre ground once through a Wilev mill fitted vith a 1 mm xreen. Equal proportions of ground material from ell collection area wre composited by speci• for each sample period . r '· r i I· 1- 31 Stltpnltll. c. .......... ., wn .... ..,. il mm ... bit drv lllltter (IYDOI1) .. .. r_. t11C411• f,... 1 YiW -.U.CW .. tM ICeMi PHi_. ,...... ~ C..W (ttiE). IYDDt1 ........ wn CIMZW It t1AC fld1itiel fl'llwill tlal _.... tulli-' .. PelnH ( 1970). IVOOtl n,aicM wn na i1 tn,a~ tw ..n ..... 1M tM •IXJ"IIII• • percelt If......,*' ..tW. trilla,..-.... .,.. •riAined ~ tbe w.ct .... ..,. wbli .. (Ita end JtMIH 1976) wn c:eMucW i1 4up1icetlea the •• c:empotit. ••pi• ~ U. Pll_,. (Aielb) Plut ... Seilt ~flit liMrtWI-Cnlll prMI WI ati..W 111J Mlill ... fleW 6.25. CHVWt • .,... Mil pit of wriaa (ADA) 2-flcter flderial desita usift9 speda tAd 111np1t perWI • flcW1 WI Ulld to •teet at.tiatic:el 4ifftrt11C81. Multiple c:emperiaon of ntns WI colductld Mlill I pntlctld LSD ,_..,._ Sitnificoct 1ewl fer all atatimc:eJ tab WI .t et alpM • 0.05. RESUlTS Then WI no litnificent difference (P)0.36) in IVDDM betYetn •mple periods for env of the •• tpecieiMmpltd (fit 2). ND aitnifictnt (P)0.06) 2-wv interections betv:en tpeciea lftll " ...,1e perieds wre detected. vlricb ellowd peeling across saMple periods (Teble 2). Eliminetion tf •untli n cnnberrv. sampled onlv during December. did not effect the results of the enel pit. Meuntein crenNrrv hid the lri9heat IYDDM emong the 7 species 11mpled; deep tnov , ...-. 1 ) precluded itt collection during the Mtrcb sample period (Table J2):3 ·There wre significant afferences in IVDDM poeled ecnsa MIRple periods emong the 7 shrub speciea. Multiple comperi10n of Mmplt meena ahowd t het IVDDM wa not different emong ditmondleef. tnvleef,end Richerdlon YillOYS. but feltleef Yillov hed significantly lover digestibility . then the other Yillovs. IVDDM of both paper birch end resin birch vas significantly lo-wer than ell of the YillOYS Yith the exce ption of feltJeef Yillov. IVDDM of paper birch vas aignificantlv different from thet of resin birch (Table 2). 32 Stettenettl. TMrl WII titlificelt (Pc0.0()4t) 2-WIJ iMtrtdiH fer era proteil Mtwaa t,.cia 1M a..,ae ~ YIIH paper ~,g WI ildliiiM il tM NINA . Whel peper bircla WIIXCl_., tw. we MlitRifiCMt (P.0.-42) tMir"lctiM aM • llifference ( p,o.1 5) Mtwl• •• ,.,-iGII -fw uude "*ift t1 tM rnlliliRt 6 a,.a.. E1imineti0ft of .uatain cnUirrt, ...,aM HI' •.nftiJ December,~ lit affect tM retulb ef the tnei'J'is. Cr .. protein we pooled acna. ....,.. periodsfor...,.ritt•tf_,.. .... fer an sptdesexcept ,.,.r ~rcla (TMII 3). Awl• cr• ,_. ceMiat we ldtMit for relin lrircla, tRd 1....t fer •••• UMberrv (Teltle 3). Cr .. ,...lwtb fer paper bircla wre lillrilar te u.. fer reli1 lAm il ......... ,.. ,.,.... (fit. 3). OieiM .. IIfvillw ... the highest, end trtt~lllf-~ Yi11w te.l....t, cr .. protei• values ofthe Yi11ws (Ttble 3, Fit. 3). There wre litfific:Mt differe i1 crude "*• lewlt ._.. tM 6 wa apecia pooled ewr .. ,.. ,.,.-(TMII 3). With the exceptioa ef tnv1tef Yillw and Rict.nboa YilJw, vhicb wre limilar ia grwth form end size of current enaual trevth tYi91, the meent of ell other tpeciet wre differtod. There vas lrigh correlation (r•0.95) between crude protein values of the same species (excluding mountein crenberrlj) compered betveen December end March tample periedl, IHit trends over time wre not consistent (Table 3). Crude protein values for peper birch, resin lrirch, end trtljleef Yillov incr..., from December to March , ..,hile values for diemondletf YilkN, feltleefYillw,tnd RichenboaYi11wdecreesed (Teble 3, Fig. 3). A litnificent iiMrta correlation ..,.. found betveen IVDDM end cr .. protein values compered for the aeme speciet Yithin December (r•-0.82) end March (r•-0.81, using December vah• for mountei n cnnberrlj) aemple periods, end vhen pooled ecroa tample peri .. (r•-0.75, excluding peper lrirch). DISCUSSION In vitro digesti bilities of individual Yi11ov 'pecies reported in this studlj wre si nrilar to thole reported blj other reseerchen. 01demelJ8r ( 1974) reported IVDDM ustng moose rumen inoculum mreged 34.5,; end 37.3,; for litfletree Yi11ov ( Sellx erbusculoides) collected on the r r r ,~ I 35 ~ehl. Mtlf,..jwtlile,...cellli•..n•teStiH-illlllitiRtt .......... Kleil (1977) ... Br .... ( 1981) ,..,.rWtMt Wth rlliaCHtellt If -..J Hlet3 If ,.,.r ~rcll...,.rM Wwli., ~tMVIW MA (Ul!lt!!!rict!P). 81111 sMib fnNRIIirth trMI (~!b~Jai!!I!Jt tMJ. tttme•> wn ~Watt receiw lewr brwi1Rt ,nsturt frHt .....Wa lwl (lu!l ti!l!ifw) tallr'tMr•Swdl• (DIMll.., .._-Due111985). 1111t 11 the ,.,.,. llim ewi~H~e • w..... t• thett-. .,. ;. -.. .... lrili., ,_ IYif'-..t .. trMI. Tvtt••JJI• ceiW fer tJiit st ... wn lllltltilllt Ill,,... Mltl ..... The,..,. .... ,... fltllllllewr ..-.~.r~ttt blltl •ILl Mp t• the ••pl• MtvXpllil tM tHtnllt •~enpenciJ t•IVDOH bltwe• thb atudv lAd retUlb re,orW fn11 tltt Kelli PIM•• 1111 t*rilr Aletb vlten • ._ ... ,.,.,.birch pltnb wn t..,.,.._ t•-.. (LtAtlcltt ... DMa 1913), tliiHI' ... n~utb.,.. Mll'ln Wttlticl1 tl U.. If Alfllt• .. el. ( 1986). !! Yitrt •••• If ,.,.r llircll end resin lArch M91Mtll• .. .....,. U. tltt ·.,.. nw· tpteM flf ru•• difeatjeft vhen reiMWI or lilutiOft tf texic nat• -. ...._. di,.tt lrilitv ( Peraon et tl. 1980). Meuntltn creMerrt Md the hifhest digeatilrilitv of the MY~n species tilted. Sevenl other ttudia hiYe tllo IU!JIIIted tMt diteftilrilttv of moufttein crenlaerrv WI ~·e1nt1v lrifll i• reletioft te other~, fertl)lletten IHj .._.during Yinter. For exa11 3Chi tRd Dwia (1973) reported 50.1K IYDDM uaint Mvine inoculum, end Olde1R191r ~ 11 . (1917) fHRII 41.8K usint mooae rumen fluid end 40.8K usint deirv etN inoculum tft thl Ktnet Penineule vhere mountain crenberrv WI In important Yinter fonge perticultrlv vhln tnw WI ftOt deep. Our tbtervetiont auggtlt thlt moose in the middle Suaitne baift ltud9 lrtl entered through light anw cover ( <25 em) in Oecemlltr te reach mountain crenberrv. But bt Hem, vhea anov daptlll hid accumulated to over tpproximateltJ 60 em, cretering for this lw-trwint ctwarf shrub w. ren. Oldlmever ( 1974) report~ lowr IYOOH wluea for mountain crenberrt then ether studies: 36.0K end 37.4K usint moose rumen inoculum for Februer~ ~nd Herch atmples, AS"J*tivtl~. r 1:~ r I r r f ~~ I --. . 36 s.etten et 11 . Dietz et II . (1962) ,...,.._,., • miliiRUIR fiA 1• cr• ,..,n fer IIN"WWItl .- c:eMitilft mult •r (O!IIcoilt• l!ll!it!W) vt•r ,.... Similerlt, Rlfeli• et tl. ( 1986) ncetMnt_.. thlt vinttr ,..ui,....MI te Mlltlillit,..n Mltnce If tM1t ..... •hHW lilt ..t r.vlitttrv cr• protein 1r41a of 6.5 •. Three of 4 vi11w species tnd mouatttn criMerrt 111 bid crude pntein lewis lowr thin the ncommeAded 6.5 •. The crude protein wh• fer the tlwu species investi91ted durint vtnter in thit ttlllv wre 911Wt11t c:omperHJt vit._ ltlw p~ithM iafennttiOA . Avenge cr• protein ctnteRt If 7.0• wa reporW fer fe1tletf villw i1 iDterier Alesta (Milke 1969) compered te our 6 .24•. Oiemend1eef vtllw in interior Alesb ,..,... from 5.4-5.6• (Mtcbide 1979), vbich WI lwer then the ~Wrage of 6 .92• c"* pretein in our studv tree. Crude protein IMAging 5.4• va found for meuntein cnnberrt •• both leRelche end Dwit ( 1973) tnd 01deiMIJir et el . ( 1977) on the Klnei Ptni •ule, comperM tl 5.25" dun ng December in the Susitna besi n. Because it is an ewrgreen abrub, most studies hiYe •hw• that mountain crenberry meinteined a loY but reletively uniform crude protein 1ew1 veer- round (01demeyer and Seemel 1976, Regelin et al . 1986). In contrast, Scotter ( 1965, cited iD 01demeyer 1974) found higher lewla of cr• protein in mountain crenberrv of northern Seslcatche'tfan; 7.9" and 6.3" in September and March, respectivelv . Oldemeyer et el. ( 1977) reported 8.5" crude protein in peper birch during Jenuarv,end cited Kenai National t1oose Ringe (Kenai National Moose Refuge narrttive report: Mav-August , 1963. Kenai, Aleslce. 25pp.) • hiving e vinter average of 7.5" on the Kenai Peninsula . Coven et el . ( 1950, cited in Oldemeljtr et el. 1974) found crude protein lewis ewreqing 6.1" during vinter compared to 8 .25" in our study. It is possible both crude protein and digestjbilitv could wrv over time as e result of changes in eveilebility of different plent perU. As vinter progresses, fever current ennual grovth tviCJS remain to be brovsed. Those tviCJS vhich do remain cen be of lwer nutritional qualitv if thev have been previouslv brovsed. Brovsed tviCJS have a Jerger remaining diameter end lack terminal buds, vhich contain the highest t~rotein content (Coven et al. 1970, Wolff r r I b r I ,. r 37 Stei,en et ••. 19n) eNien ..,. ... We . If tlis ws U. ca, tlwn • ceASistellt dec:lilill tnftll tver ti• w.N lie apecW. Ow.._ • lit lhw tlia treM. Our ~electiea ef predNl1•110t ~ tvifl ia lllth aeiAplt perieds W.W tellll tl ertificilll g auppress this triM l\ler tJat Mp • ..... IRifld ,,__ Thtugh ttatittic:ll telb thewd a signific.nt inc,.... in crllde prot.ia coatlllt Mt\.•a aample period meeftl for peper birch, it it our conclusion that the detected difference vet en ertifect of fieW Mmpling tnd lw Mmpltlize end do not npreaent r•J chenget through time tMt wul.t directlt influea DutritiM of foraging 10001t. We knov of no bielogicaJ reeaon ¥hV u• prttlin conta.t .t peper birch wuld inert~~~ during the ¥inter dormencv period . Further suppert for tlw cenclllieR tMt cr• protein lewis pre ba blt did not change ia the interiiA Ntwt• Dec:eMIIer w Minh comt1 fntft Beilet ( 1967) and Lavcock and Price ( 1970) ¥ho feuM thlt cr• proteiR comfit of lwwte does not change apprec1ablg durint tlw non-.,.wing ...... I MPUCA liONS These results heYe thwn that fli9esti Mlity and crude protein content of major food items eveilablees for• for mooae 'tiiaring in the middle Susitne River basin vary by species. Neither digestibility or crude protein content probably verv once the plants hiYe bec:ome dormant in the fall; thus a single 'Iii nter -long ~Yerege should be obtai ned for eech species uti ng the data from both temple periods . The results tuggllt thet digestibility among ctiamondleef, grayleef, and Richenbon 'tiillws wre not different; tMIJ could be combined and a single everege digestibility (35.2~) uaed . HweYer, differences in crude protein content among the 'tiillw spec1es tuggetts thet values should be individuelly determined . ltn everege crude protein content (5 .94~) could be uaed for greyleef 'tiillw tnd Richerdaon 'tiillw. Mountain cranberry had the highest digestibility but the lowst crude protein content of the specie$ t~ted Its d'Yerf grovth form mem 1t of limited IYiilabilityes for• in the study area during the period Jenuarv through April in ¥inters of light or eve,... sno'tifall and December through April in ¥inters 'tiith early, deep sno'tifa11 . LITERATURE CITED I k. r 38 Stetten et 11 . LITERATURE CITED Blileg, J.A. 1967. Slmp1ingdeerltrwae for crude protein. J . Wildl . Manege. 31 :437-442. Bi•l1, H. D., end H. St,.... 1955. TM cr• pretein venations in tbe browe diet of Ce1i fwnie deer. Ce1if. fish tad Gt1n1 41:145-155. Brwn, D.C., eRd J.C . Rlllclifft. 197 1. Prediction of in ~ dnJ metter, ervenic metter, end enertv ditlltibi1itiea tf til• bv i! vitro digestion techniques . Aust. J . Afri . Aea . 22:787-796. Brljlnt, J .P. 1981. Phvt&chemic:~1 deterrence of snCNShoe here brovsing bg edYentitious shoots of four A1t~bn treet. ScieRCe 213:889-890. town, I.M., W .S. l:to6r, end J. Hitter. 1950. The effect of forest succession upon the quantity end upoR tht nutritiw YlhM ef wody plenta Ul8d 11 food by rnooee . C.n. J . Ret . 28:249- 271. town, R.l., J.S. Jorden, J .L. Grimea,end J .D. Gill . 1970. Comperetive nutritive v.luea offorege species. Pages 48-56 in ti.A. Pe ulsen, E.H. Reid, and K.W. Parker, eds . Rer.ge end 'Wildlife habitat oveluatioR--e research symposium. U.S . Dep. Agric., For. Serv. Misc . Publ. 1147. 220pp. De nell, IC, end K. Huss-Denell. 1985. Feeding by insects end heres on birches earlier effected by moose brovsing . Oikos 44:75-81. Dietz , D.R. 1970. Animal production end forege quality. Pages 1-9 in H.A. Paulsen, E.H. Reid, end K.W. Parker, eds . Range end 'Wildlife hebitet evaluation--a research symposi um. U.S. Dep . Agric ., For . Serv. Miac. Publ . 1147. 220pp. --· R.H. Uda11, end l.E . Ve8CJ8r . 1962. Chemic:~l composition end digestibility by mule deer of selected forage species, Cache le Poudre Renge, Colorado . Colo. Geme end Fish Dep . Tech. Publ. No . 14. 89pp. Gesewy, W£.,end J .W. Coedy . 1974. Reviw of energy requirements end rumen fermentation in moose and other rumi nanb . Naturaliste c:~n . 101 :227-262. ) r ' 39 Steitmehl. t.:c, R.A ., 1M W .£.Jill I IlL 1976. Detenli.ttH of totel nit,..a i1 pleat till• llint • ~ect ,.,..tlr. J . A.O.A.£. 59:98-100. Khli1, D.R. 19n. wtNr fiiCI ,..,.,.. ... of tnwshoe ._,... (J.!u! ••riclftw> in tnterier Alesb. Pnc.IRt. Celgr. C..... Biel . 13:266-275. l.lpct, W .A., end D.A. Pnce. 1970. Ell'linnmentel influences • autritieMl wlue of ,.,.. plub. P.-37-47il H.A. Peultel, E.H . ReM, end IC.W . Pvbr, ... R.,. 1M viNiifl Mlritet 1¥11Uition--• ,_,reb SIJmposium. U.S. Oep . Agric., for. Serv. Misc. Publ. 1147. 220,. leRacM, IU., eiMI J .L. Dwis . 1973. lmportaace .t nnbrwse fledl i8 1n0011 ea till !Celli Peninsult, Alesb. J . Wildl. Menage. 37:279-287. Heclddl, S. 1979. Difftreltitl Ull of Yillw speciet bv moose i1 Alesb. M.S. Thesis . Univ. Alesb, flirbtftb. 97,. Mila, G.£. 1969. Some moose-Yillw relationships in the interior of Alesb. M.S. Thesit . Univ. Alesb, fairbenb. 79pp. MorniOR, F.B. 1954. Feedundfeeding, 21tttd. The Morrison Pult'I.Co. ltba, N.Y. 1,207H. 01demever, J.L 19 7 4. .Wutritive wl ue of moose forage . Natureliste can . 1 01 :217-226. --· A.W. frtnzmenn, A.l. Brundage, P.D. Arneson, end A. nvnn. 1977. Brwse qualitvend the ICenei moose population. J . Wildl . Manege. 41:533-542. --· end R.IC. Seemel . 1976. Occurrence end nutritive qualitv of lwbusb crenllerrv on the ICenei Peninaul~. Alesb. Can. J . Bot. 54:966-970. Peer11n, H.A. 1970. Digestibilitv trials: in vitro techniquea. Peges 85-92 i! H.A. Peuben, E.H. Reid , end IC.W. Parker, edt. Re,. ~...t Yildlift helritet 1¥11uation--e reseercb svmposium. U.S. Dep. Agric., For. Serv. Misc . Publ. 1147. 220pp. Person, S.J., R.E. Pegau, R.G . White , and J .R. Luick . 1980. !! vitro and nylon-bag digestibilities of reindeer and caribou forages . J . Wildl . Henege. 44:613-622. ... . • • L I ' ~ I I ~~ I I~ ~- 1 I 40 Rltlli•, W.L., C.C . ScMrtz, end A.W. fruzaaa. 1986. Effects of fenst s~ M ntrititMI .,.._.fl .... ,.,.._ vmnvv (ia prea). AliMIMIYir, IC.l., L.A. Rlnecur, end L.£. Morttntini. 1985. Effecb of teeo•rv metoolit. from bllsem popler end peper birch on cellulose ditution. J . Range Mlnege. 38:370- 372. RobbiM, C.T .,end A.M. 11Dea. 1975. Composition and digestibilitv of MYerel deciduous bnN~~~ in the northeelt. J . WiWI .1'11M9e. 39:337-341. -· P .J. Y•• Seest, W.W. Mlutz, end A.M. Moen . 1975. f~ enelepes end digestien Yitll reference to ... bite-tailed .. r . J . Wildl . Mlnege . 39:67-79. Scotter, G.W. 1965. Cbemicel composition of forage lichens from northern Saketchewn 11 releted to uee bv l•rren-tround ceribou. Can . J . Pl . Sci . 45:246-250. Short, H.l. 1966. Effects of cellelose lewls on the apperent digesti bilitv of feeds eeten bv mule deer . J . Wildl. t11n191 . 30:163-16 7. Steigers, W.D., Jr., D. Helm, J.G . M3cCracten, J.D . McKendrick, and P.Y. Mlver . 1983. 1982 plent ecolotV studies. Aletke Powr Authority, Susitne Hljdroelectric Project. Anchorage . 288pp . --, W.L. Regelin, E.f. Becker, C.L. Elliott, and J .G. Mac:Crtcken. 1986. Winter food habits If l1l003e in tbe middle Susitne River basin, Alaska. Submitted to J . Wildl. Mln.je. Viereck, l~., and C.T. Dvrness. 1980. A preli mi nerv classifiCition svstem for vegetation of Aletta . Anchorage Workshop on Clmificetion of Alaskan Vegetation . USDA for. Ser., Pte. WI for. and Range Exper. Sta., Gen. Tech. Rep. PW/-! 06. Wolff, J.O. 1977. Hali~tat utilization of sno..-sho..-hares ( lepU$ americanus) in interior Aletlca . Ph .D. Dissertation. Univ . California, Berkeley. 150pp . I I FIGURES [ I· 41 Steic,en et 11. LIST Of FIGURES Fig. 1. Sites yhere shrub samples wre collected for nutritional analysis in the middle Susitne River besin, Alaska . fig . 2. Comperiaon of percent IVDDM of current ennuel grOYth Mgs of 7 shrub species collected during 2 Yinter aemple periods in the middle Susitna River besin, Alaska . ~ Fig. J. Comperiaon of percent crude protein of current annual grOYth Mgs of 7 shrub species collected during 2 Yinter aemple periods in the middle Susitna River basin , Alaska . 0 0 Mile I 10 10 20 Kllometere ~,,.,,.,. ten-to 20 30 --, . • N 45 40 35 30 Percent Cl Paper birch II Resin birch IVDC\'v1 25 1.1 Diamondleaf willow 20 rm Feltleaf willow 15 ~ Grayleaf willow 10 liD Richardson willow 5 = Mountain cranberry 0 December 11-13 March 5-7 Sample Period Percent Crude Protein 9.00 -r--------------- 8.75 +-------------- 8.50 +------- 8.25 8.00 7.75 7.50 7.25 7.00 6.75 6.50 6.25 6.00 5.75 5.50 5.25 5.00 1-----a Paper birch -----• Resin birch 1-----• Dlamondleaf willow ----ED Feltleaf willow f----~ Grayleaf willow --0D Richardson willow I;; Mountain cranberry December 11-13 March 5-7 Sample Period -. r r. I I ~ I I t r I I ~ [ I· I· I I 45 Sllltm et 11 . TIMe 1. S1tes Yben carnat IIAU11 tmflb NIOS from 1 shrub spectes wn co11et1ed dur1ng Oec:eiUer 11-13. 1984 end Mlreb 5-7. 1985 t n the middle Susttne Rtver best n. A lata. fer~ge Species S1te SetDJleStze 2 3 4 5 6 1 8 9 10 11 12 14 15 16 Dec. Mlr. Paper birch B' 8 8 8 8 5 5 Resin btreb 8 8 8 B B 5 5 Otamondleaf vfllov B B B B B B 6 6 feltleafvfTlov B B 8 8 B 5 5 Gregleaf vfllov B 8 0 D 4 2 Richardson Yillov D B D D 0 8 6 2 Mountain cranberru 0 D D D 0 5 0 a B = Both sample periods ; D = December t 1-13 sample period onl v. -------------- 46 Stltltnth1. [ TIMe 2. .,_,. SIJ!Uo*t ............ Mlfltlfcwrnt IMUI1 ~IYttl (YWI It· ..... fir ...... ICtMIIIrrt) If 7 .......... Cl'llectM 41uriDt 2 Yillllr ............ il r U. .wit SulitM Riwr Mlil, Alesb. [ f.,. s,eciet DeceiDIIer 11-13 Merela 5-7 BDI•PerWs I; so ...... so so fi Peper bi rcla 24.41 3.0 24.4 0.9 24.4 Ab 1.7 ~ Alsi R lri relt 25.5 0.5 27.0 1.4 26 .3 a: 1.2 feJtltlf ..nnw 28.8 1.6 26.5 1.1 27.7 c 1.8 I! GrevJeef Yi11w 34.9 2.3 35.1 0.3 35.0 D 1.5 II Richenbon Yi11w 34.7 1.5 35.4 0.5 35 .1 D 1.1 Oiemondleaf villl'lll' 36.8 0.4 34.3 1.0 35.5 D 1.5 f ~~ Mountain cranberrlJ 42.6 0.6 42.6c E 0.6 1r a Pooled means vithin column fo11wed blJ a different letter are significantlv different . 1~-b OnllJ 2 replications . c December temple period onllJ. r l II I! II ll ~- r l~ r r I· I St1t9tn et II . T_... 3. Awl IllS cr• pntli1 CIMent of current tMUil 9rwth tvitt (YMlt p1ent fw mountai R cnftllerrv) .r 71hrR 1pecies cellected during 2 Yiftter semple periods in the middle Suaitne Riwr IIIIi A, Alesb. DeceiMer 11-13 Hetn so Hetn so so Mountain crenberrv 5 .25 0.0 5.2S8Ab 0 .0 Richardson Yillw 6.03 0.04 5.75 0 .27 5 .89 8 0.23 : Grevleet vmw 5 .97 0.23 6 .00 0 .0 5 .99 BC 0.13 feltleef Yillw 6 .25 0 .08 6 .22 0 .04 6 .24 0 0.06 DiemondJeef Yillw 7 .00 0 .08 6.85 0 .05 6 .92 E 0.11 Resin birch 8 .25 0.0 8 .26 0.18 8 .25 f 0.10 Peper lri reb 7 .97 0.04 8 .53 0 .04 __ c a December semple period only . b Pooled means vithi n column follo-wed by a different letter are signifiC8nt1 y diffe rent. c SignifiC8nt 2-vey interaction betveen specit$ and sample periods. 47 ,.. SECTION II .------- r 48 SECTIOII II -MODEL IJfPUTS Monthly Diet CO!pOSition, Disestibility, and Crude Protein t••~ts fro. the food habits study (Section I) doc::U11lented the senera, QlCl iD s~ cases species, of plants doainant in the diets of aiddle basin .oose. There vas variation in proportions of e.llcb food ite. a.oos areas, though the basic food items were present in all areas sa.pled. Laboratory calibration of diet proportions through differential digestion and frag.ent identi.fication vas not successful priaarily because of aisidentification of species using the aicrohistological technique. Though these results highlighted the imprecision of this technique, they still provided needed quantitative insight into the presence or absence of .ajor dietary items and gross dietary percent composition. To arrive at monthly dietary composition from dietary information sw.aarized over the entire project area vas an exercise in combining both documented data and undocumented field observations into a best educated estimation. Willow made up the largest proportion of the average moose diet in the project area. The major willow species present and browsed by moose were diamondleaf willow, grayle af willow, Richardson willow, and feltleaf willow. Diamondleaf willow was aost abundant, while feltleaf willow was the tallest growing and provided a mid-to late-winter forage resource growing along riparian streams. These 4 willows were used in preparing the willow component of the average monthly winter moose diet in the project area (Table 1). .L Percentages of each willow species were estimated based on knovn availability, abundance, distribution patterns, observed patterns of use by moose, and height struct ure. The dietary proportion of resin birch r l~ I r 49 vu eatabliahed u a .at.ua but C01llliatent 15% throughout the vi.nter aDd apring .onths (October through May) (Table 1). Mountain cranberry vas stabilized at 20% of the diet during the October through Deceaber period. decreased to 10% during the winter .ontbs vith deeper snow (January through March) • an.d then increased again during April ( 15%) and May (25%) reflecting progressive .elt of the SDOV pack and its availability as browae prior to spring plant phenological develop.ent (Bela and Mayer 1985) (Table 1). Priaarily because of its lov availability and U.adted distribution, paper birch vas liaited to a .axt.u. of 4% of the diet during aid-winter (Table 1). Average digestibi.lity and percent crude protein values used for calculating predicted values froa the sua of the ca.ponent forages are also shown in Table 1. Nitrogen was calculated from percent crude protein for direct input to the carrying capacity model. Calculated results for average monthly diet digestibility and crude protein content are w.aarized in Table 2. Diet digestibility and crude protein values for the sUIDIIler months (June through Septeaber) were obtained from studies conducted on the Kenai Peninsula (Regelin et al. 1986) and are also shown in Table 2. Digestibility values were calculated from entire current annual growth twigs clipped at the bud scale scar. The average digestibility values assume. in theory at least • coaplete utilization of the entire twig at one time. When utilization levels are less than 100%, (e.g., SO%}, it i s probable that average digestibility of the terminal portion of the twig ingested may exceed average digestibility obtained from the entire twig. Moen (1985) has documented that red maple (Acer rubrum) r so twta• a .re .,re hiply diaeatible (up to 1641) at the diatal ter..ioa.l bud thaD at the proxt.al bud scale scar. Field observations have suggested that, in a high-use area, .oose browse twigs of feltleaf willow progressively shorter through the winter rather than consuming an entire twig during a single feeding. However, for the shrub species we have used in average aonthly diets (Table 1), only feltleaf willow bas sufficiently long twigs that an upward adjustaent in average digestibility and crude protein levels could be considered necessary. The other 3 willow species and both paper birch r and resin birch all have small current annual twigs that are usually allaost entirely re.aved in a single bite. The entire aountain cranberry plant is also consumed in the saae manner. Observations of the degree of utilization of feltleaf willow in the project area suggest that this t. species is very heavily browsed, with almost the entire current annual r growth twig having been reaoved by spdng . Moose conswaing higher quality terminal buds in December would subsequently be consuaing the lover quality proximal end of the twig in March and April. This would result in an average diget.-ibility and crude protein content over the winter similar to that calculated for the entire twig, but a decreasing digestibility curve over the course of the winter. The digestibility and crude protein values reported in the Susitna studies {Section I, Forage Quality study) were comparable to those reported by other researchers in Alaska. Diet digesti bilities calculated from sums of the component forage items were very close to those experimentally deterained {Section, Food Habits study). In v i tro digestibilities using bovine rumen inoculum also compared well with t hose obtained from moose rumen inoculum. Because the willow species l M l i' r. t 1::: 51 were ca.biDed for forage bia.aaa calculations (Becker aad Steiaera 1986) aDd the above arau-enta. it 1a not reca.aended that a correction factor be applied to .anthly diet digestibility or crude protein valuea calculated in Table 1. Monthly Diet Subatitution ln co.puting carrying capacity. total available forage bioaass of all aubject species is offered for cotl8lmption over the specified tt.e period (e.g.. 100 days) the .oose are expected to be on their winter range (proposed t.poundaents). Allocation of forage bia.ass resources is constrained by aut.. percentages of each species allowed in the diet. When the upper Uait of the allowable dietary proportion is reached for diet itea A. diet itea B is substituted until its upper limit is also reached. and then diet item C is substituted. etc. Maximum allowable contributions of each diet item for project area moo • . .: were derived from the literature and from field experience. The 3 plant species requiring estimates of upper limits were paper birch. resin birch. and mountain cranberry . The contribution of willow in the diet is considered limited only by availability of total forage b l omass once allowances have been .ade for environmental liaitations such as snow depth. Research on the Kenai Peninsula has suggested that a reasonable aaxt.um contribution of paper birch in the diet of win tering moose is about 70% on a nearly monotypic paper birch study area (LeResche and Davis 1973). There is evidence that at higher percentages rumen activity wa y be inhibited by the resin content of paper birch (Reisenhoover et al. 1985). Paper birch is 11mited in abundance and is sparsely distributed in the project area. The 70% maximum dietary f r 52 contributioa vas uaed for paper birch even though project area .ooae could not likely achieve this level for chose very reasons. Resin birch vas not saapled for forage bi~&s in the project a rea because of its rather ubiquitous distribution and virtually unlillited abundance of forage bi011188s. Information from the food habits study (Section I) identified a aaxtmum dietary contribution of 16%, averaging 11% over the entire project area. Murie (1944) reported :-bat resin birch vas regularly browsed by moose during winter in Denali National Park, though LeResche and Davis (1973) and Spencer and Hakala (1964) considered resin birch of minor dietary importance. For the Susitna project area, we recommend a maximum but consistent dietary percentage o{ 15% resin birch throughout the period October through May. Mountain cranberry bas been reported to comprise up to 51% of the winter diet of moose on a depleted range on the Kenai Peninsula (LeResche and Davis 1973). Howe·.rer, on a normal quality range on the Kenai Peninsula the maximum winter dietary proportion of mountain cranberry was 21% (LeResche and Davis 1973). On the depleted range but not on the normal range, mountain cranberry made up nearly half of the diet (LeResche and Davis 1973). Cushwa and Coady (1976) also noted that frequency of mountain cranberry in moosL rumen samples was higher during spring than during winter on the Kenai Peninsula, but that i.t was nearly absent from samples taken from the interior near Fdirbanks . Deeper and more yersistent snow accumulations in the interior make mountain cranberry less available that on the Kenai Penins ula. The Susitna project area is in a transitional zone between the interior and southcentral coastal climatological zones. Average snow depths exceed those on the Kenai Peninsula (compare Steigers et al . 1986 r !<> I r 53 and LeReacbe and Davia 1973), but are leas that, t h .1se in tbe interior near Fairbanks. Tbua .auntain cranberry is considered to be available for a aborter period during tbe winter tban on tbe Kenai Peninsula. Dietary coaposition in tbe Susitna project area ranged froa 1-41%, averaging 8% over tbe entire area (Section I, Food Habits study). Mountain cranberry is considered to be at its lowest availability during the January tbrougb April period. For purposes of diet substitution, a aax~ winter diet contribution of 15% is considered to be reasonable for project area aoose. Mountain cranberry as a dietary component is not U.aiting in total biOIB&Ss production, but rather solely becalise of lillitations in availability. Literature Cited Becker, E.F., and W.D. Steiger&, Jr. 1986. Moose forage biomass in the middle Susitna River basin, Alaska. Alaska Dep. Fish and Game for the Alaska Power Authority Susitna Hydroelec~ric Project. Cusbwa, C.T., and J. Coady. 1976. Food habits of moose, Alces alces, ir Alaska: a preliminary study using rumen contents analysis. Can. Field-Nat. 90:11-16. Helm, D., and P. V. Mayer. 1985. Plant phenology study. Univ. of Alaska, Agric. and For. Exp. Sta. for Alaska Power Authority Susitna Hydroelectric Project. 256pp. LeResche, R.E., and J.L. Davis. 1973. Importance of nonbrowse foods to moose on tbe Kenai Peninsula, Alaska. J. Wildl. Manage. 37:279-287. Moen, A.N. 1985 Season and twig-length effects on cell composition of red maple. J. Wildl. Manage. 49:521-524. r ~~ I· I I ~~~ I !·~· r r I· I Murie, A. 1944. Ser. No. 5. 54 The wolves of Mt. Mc~.inley. U.S. Nat. Park Ser. Fauna 238pp. Reisenhoover, ~.L •• L.A. Renecker, and L.E. Morgantini. 1985. Effects of secondary .etabolites from bals8111 poplar and paper birch on cellulose digestion. J. Range Manage . 38:370-372. Regelin, W.L •• C.C. Schwartz, and A.W. Franzmann. 1986. Effects of forest succession on nutritional dynamics of moose forage. Viltrevy (in press). Spencer, D.L •• and J.B. Hakala. 1964. Moose and fire on the ~enai. Proc. 3rd Ann. Tall Tblbers Fire Ecol. Con.f . Tallahassee, Florida. 3:11-13. Steigers. W.D •• Jr., W.B. Ballard, and E.F. Becker. 1986. March 1985 snow depth survey in the aiddle Susitna River basin, Alaska. LGL Alas ka Research Assoc. • Inc. for Alaska Power Authority Susitna Hydroelectric Project . 73pp. r 55 Table 1 . Monthly diet composition and percent digestibility, protein, and t~ nitrogen con t ributions to the winter diets of moose in the middle Susitna River basin, Alaska. I ........ Oot.bw Ditt M)tl) Protm Nitr091ft Dlft"'"' ca; Dlft "~-"IYDr1) secmr . ,. Protm " CGntr . Cantr. vm.w G4 G4 DUmandlt~ 6:5 41.6 ~~ 14.77 6 .92 2.88 O.Q04606 GnglNf 10 6 .4 35D 224 5 .99 0.38 O.D00613 ~ 10 6 .4 ~-1 225 5.89 0.38 0000603 F'•lt1Nf 15 9.6 77.7 2-" 624 0.60 OD009SJ I P..,-Birctt 1 1 24.4 024 8.25 o.oa 0.(0)132 R.msrch 15 15 26.3 3 .95 8.25 124 0.001980 Cr~ 20 20 42.6 8~ :i2!5 1m 0.001680 I TOTALS 100 100 ~..£2 6.61 OD10573 Mon1b = NovftNI«' Dlft IYDr1) Prottm NttrOCJIO ,. Ditt"'"' • Ditt ·~-• M)tl) •c-tr. • Prot=in • Ccmr • c-tr . \'Blow M 64 OWnondiNf 65 41.6 35S 14.77 6.92 2.88 0~ Gf"I91Nf 10 6 .4 ~D 224 :5..99 0.38 O.D00613 Richwclson 10 6 .4 35.1 2.25 5.89 0.38 0000603 ftltlNf 1:5 9.6 77.7 2.66 6.24 0.60 0~ P..,-&ra 1 1 24.4 0~ 8.25 o.oa 0.(0)132 RHW'!Brdl 1:5 1:5 26.3 3 .9:5 8.25 1.24 0.001980 Cr~ 20 20 42.6 8.52 5.25 1DS 0 .001680 TOTALS 100 100 34..62 6.61 OD10573 ! Month = o.o.n... Ditt M)tl) Prot.W\ NitrOCJM r Dlft ltfm Sl>lft .. ~. SMH> secmr . " Protm .. Contr . Contr . Yillow G4 64 ~ ~ 32 ~~ 1 t .36 6 .92 221 O..oo3:543 Gr~1Nf 10 6 .4 35D 224 5.99 0~ OD00613 Rtc:Nrdson 10 6.4 ~.1 2.2!5 :5.89 0.38 0000603 F•lt1Nf 30 192 Z1.1 5.32 624 120 0 .001917 P..,-Brdl 1 1 24.4 024 8.2!5 o.oa 0.000132 R.msrch 15 15 26.3 3 .95 825 124 0.001980 :n.lbemj 20 20 42.6 8.52 5.2!5 UJ5 0.001680 TOTALS 100 100 33.87 6.54 OD10468 Mon1b=~ Oitt M)tl) Prot•W\ Nibogth Oitt lt8n .. Oitt .. ~. .. M)tl) .. c-tr . .. Prot.w-..Contr . Contr. Ylllow 12 12 OWnondiNf 40 28.8 35S 1022 6.92 1.99 0 .003189 Gf"I91Nf to 12 ~D 2.52 :5.99 0 .43 0..(0)690 RicNrdson 10 12 35.1 2..53 5.89 0 .42 0.()0()619 f•lt'INf 40 28.8 n.1 7 .CJ8 624 1.80 0 .0028"7:i P..,-Brch 3 3 24.4 0.13 825 0.25 0 .000396 RHi\Brdl 1:5 1:5 26.3 3.90 8.2!5 124 0.001980 Crriemj 10 10 42.6 426 5.25 0..53 0 .000840 TOTALS 100 100 32.19 6.66 0 .010649 .. r Table 1 . (continued). 56 L ....... ftllnaanJ INt M»t> ~-Nitr"Oflft Dlft .... WDift seen.. w IYDt1) WC4mr. • P'roUtl ~ C4mr. Qmr. Yilw 71 71 DlnondiNf ~ 24Z ~"' 8.82 6 .92 1.72 0~1 Gra,lNf 5 !.SS !5.0 1.24 5 .99 021 0000340 RtcNnlsan 5 3.SS 3:5.1 1.2:5 5.89 021 OF'm35 f•ltlNf S'5 !9.o5 X1 .1 10.B2 624 2 .44 OJX3899 P ..... Bi"c::h 4 4 24.4 0-'G 8.2:5 0.3! 0~ RMnBnh 15 15 2£.3 !.95 8.25 1.24 0.001990 cr~ 10 10 42.6 4.26 5.2:5 O.!S3 OlDJIMO TOTALS 100 100 31.31 6./,7 0 .010673 ~=Mwc* Dlft IYDf'l) Protm Nttrogtn INt tt.m S!Mt wee.... SMH> SCclntr. 11 Prot•WI 11 Contr. Contr. vmow 71 71 INrnandiNf m 21.3 !5.5 75 6 .92 1.47 O.oD2!58 Gr"Jlf.t 5 3.5':5 ~.D 1 24 5 .99 021 0.000340 RicNrclson 5 !55 !5.1 125 5.89 021 00003!5 Ftltlf.r 60 42.6 X1 .1 11.80 6 2 4 2.66 0,0042::53 P..,.Bnh 4 4 24.4 0 .98 825 0.33 0 .000528 bmBi"c::h 15 15 26.3 3 .9:5 8.2:5 124 0.001980 Cr~ 10 10 42./, 4.26 5.25 053 O..ooo&40 I TOTALS 100 100 3UJ3 6 .65 0.010634 r f'1oMh • April IMt IYDf'l) Prot. WI Hitr'ocJin Dlft lttm Sottt • Cor111-SIYDtl) SContr. • Prowt~ • Contr . Contr . r Yillow 67 67 Dinondlt.t 35 23.45 35..5 8.32 6 .92 1.62 O.OOZ596 Gr"JlNf 10 6 .7 !5.0 2.35 5 .99 0 .40 0..()006.42 I ~ 10 6 .7 35.1 2.3:5 5.89 0~ 010)631 F•ltlNf 45 !0.15 X1.1 8.35 624 1.88 O.D03010 P.,-Brctl 3 3 24.4 0.73 8Z5 o.zs 0 .()()(J3'96 ji RMnBinh 15 15 2£..1 3 .95 8.25 124 0.001990 Crntmj 15 15 42.6 6~ 5.2:5 0.~ 0.001260 TOTALS 100 100 !2.44 6S7 0.010516 Monti=~ Dttt IYDf'l) ProttW't Nitrogtn IMt lttm S!Mt •c..... SMH> 11 C«<tr . 11 ProttWI • C«<tr. C«<tr. Ylllow 59 5'9 ~ 70 41.3 46S 19.20 9 .73 4 .02 0006430 Gr"JlNf 10 5.9 46..5 2 .74 9 .73 O.:rl 0.(D)'9t9 Richwdson 15 8.85 46S 4 .12 9 .73 0..86 0.001318 Ftltlt.t 5 2.9:5 !9.0 1.15 9 .73 0.29 O.D00459 P..,-Bnh 1 1 D.5 0.34 11.D8 0 .11 0.000177 Rim Bi"c::h 15 15 34..5 5 .17 12.!S3 1.88 0003007 Cr~ 2S 2S 42.6 10.65 6 .43 1.61 OJJ02S72 TOTALS 100 100 43.37 9.34 0 .014942 Nott: IYDtl) w CP nllfs for~ •• 5usttM nter v•llfs plls 112 tht differtnet bttwttn Susitnl .nc~ ~.,. .t •t. (1m; S37 ~ r.-»lt 2) .Ally v•llfs. , f [ I I ,. I. Table 2. Ave r age _,nthly percent digestibility and crude protein content of calculated aoose diets to be used for carrying capacity model estiaates for the midd le Susitna River basin, Alaska. Month a September October November December January February March April June July August Digestibility Crude protein 42.00 13.38 34.62 6.61 34.62 6.61 33.87 6 .54 32 .19 6 .66 3L31 6.67 31 .03 6 .65 32.44 6.57 43.37 9.34 53 .10 18.75 53.10 15.63 44 .70 15.63 a Values for June through September were from the Kenai Peninsula. 57 I 1