ENERGETICPRODUCTION BY SOFT AND HARDMAST FOODS OF AMERICAN BLACKBEARS INTHE SMOKYMOUNTAINS ROBERTM. INMAN,1 Department of Forestry,Wildlife, and Fisheries, Universityof Tennessee, Knoxville,TN 37916, USA, email: [email protected] MICHAELR. PELTON,Department of Forestry,Wildlife, and Fisheries,University of Tennessee, Knoxville,TN 37916, USA, email: mpelton@ utk.edu Abstract: We measuredcaloric productionby 19 species of vegetation used as food by Americanblack bears (Ursus americanus)in GreatSmoky MountainsNational Parkto determinethe significance of productionby mast type, season, and species. Mean annualproduction by all species was 351,209 cal/ha. Hardmast produced74.5% (16.0 billion cal) of total calories availableon the study area;soft mast produced25.5% (5.5 billion cal). Gross energeticcontent of soft and hardmast did not differ (P = 0.488, n = 19). Mid-summerwas the lowest periodof production.Northern red oak (Quercus rubra)produced 65.7% of calories; squawroot(Conopholis americana) produced 15.8%, and huckleberries(Gaylussacia spp.) produced 5.1 %. A white oak (Q. alba and Q. prinus) mast failureoccurred, and white oaks producedonly 5.1% of calories. Oaks are likely the single most influentialgenera affecting bear ecology in the southernAppalachians. However, availabilityof soft mast likely has a substantialimpact on bear populationsbecause of the timing of production,nutrients available, and its functionas a surrogateduring hard mast failure. Furtherstudy is needed to determinethe effects of soft mast abundanceon age of primiparity,litter interval, recruitment, and density. Once the roles of majorfoods are well understood,appropriate habitat compositions and silvicultural prescriptions may be defined. Ursus13:57-68 (2002) Key words: Americanblack bear,Carya, Conopholis,energy, Gaylussacia, mast, Nyssa, Prunus,Quercus, Rubus, Smilax, Smoky Mountains,Ursus americanus, Vaccinium,Vitis Nutritionalcondition of Americanblack bears affects nent of black bear habitatsin the southernAppalachian age of primiparity(Jonkel and Cowan 1971, Eiler et al. region. Soft mast composed a greaterpercent than hard 1989), litter interval(Rogers 1976, Eiler et al. 1989), lit- mast in both annualvolume index (45%vs. 14%,Beeman ter size (Beecham 1980, Elowe and Dodge 1989), cub and Pelton 1980) and relative percent density (37% vs. survival (Rogers 1976, Eiler et al. 1989), and yearling 10%,Eagle andPelton 1983) of scatscollected in GSMNP. survival (Jonkel and Cowan 1971; Rogers 1976, 1987). Gypsy moth (Lymantriadispar) infestations in Virginia Nutritionalcondition may also influence fertility (Noyce resulted in complete acorn crop failures, yet bear repro- and Garshelis 1994). Thus, habitatswith adequatefood duction and survival in those areas did not decrease im- sources are essential for effective bearmanagement. mediately after the infestationand subsequentfailure of Because of the importanceof energy storage for the the mastcrop (Kasbohmet al. 1996). The amountof shrub denningperiod, previous southern Appalachian bear stud- soft mast availablein an areainfluences the seasonal and ies were designed to determinethe relationshipbetween annualhome range sizes of bears and their activity pat- fall oak mast availabilityand reproduction. Bear repro- terns (Garshelisand Pelton 1980, Quigley 1982). Bears ductionwas found to be highly correlatedwith hardmast with abundantblack cherry (Prunus serotina) in theirhome indices by Eiler et al. (1989), Pozzanghera(1990), and range displayed delayed movement to areas of abundant McLean (1991). However, Coley (1995) found no sig- oak mast (Garshelisand Pelton 1981). Abundantgrape nificant positive correlationsbetween hard mast indices (Vitisspp.) cropsreduced the impactsof a severe oak mast andbear population size. Coley (1995) analyzed20 years failure on bearreproductive effort (Eiler et al. 1989). of black bear populationdata to determinethe influence Managing bear habitatsrequires identificationof im- of hardmast productionon black bearpopulation dynam- portanthabitat components and determinationof the op- ics in GreatSmoky MountainsNational Park(GSMNP). timal, or at least minimal, habitat mix necessary for Coley (1995) correlatedhard mast indices from GSMNP maintainingpopulations at desiredlevels (Schoen 1990). with variouspopulation estimates for periodsup to 5 years Policies regardingnatural disturbances in nationalparks afterrecorded hard mast data, a broadapproach that should and silviculturalpractices on multiple-uselands influence accountfor the influence of recruitmentin additionto re- food availabilityfor bears. Bear habitatmanagement in production. Because soft mast availabilitywas not docu- the southernAppalachians currently emphasizes the im- mented during the 20-year period that Coley (1995) portanceof the fall hardmast component (Eiler et al. 1989, studied, the variationin populationestimates that could Pelton 1989). A betterunderstanding of the influence of be explainedby soft mast availabilityis unknown. soft mast on bear population dynamics in the southern Soft mast may also be an importantnutritional compo- Appalachiansmay lead to more effective management strategies. In this study, we examined food 1 Presentaddress: Wildlife availability ConservationSociety, 2023 Stadium the calories the of Drive,Suite 1A, Bozeman, MT 59715, USA. by measuring produced by majority 58 Ursus 13:2002 vegetative bear foods in GSMNP (59% annual volume ous studies in the southernAppalachians (Beeman and index of scat; Beeman and Pelton 1980). Our objectives Pelton 1980, Eagle and Pelton 1983, Brody and Pelton were (1) to test for differences in caloric productionper 1988). All plants were common in GSMNP (Whittaker hectarebetween mast types and among seasons, and (2) 1956, Stupka 1960, Golden 1974). to estimatetotal calories producedon the study area sea- sonally, by mast type, and by species. Sampling Scheme We stratifiedthe study areato select 275 samplepoints by (1) vegetationtype, (2) elevationalrange of each veg- STUDYAREA etation type, (3) aspect, and (4) distance from trails. We GSMNP is located along the borderof Tennessee and used the vegetation classification by MacKenzie (1993; North Carolina (Fig. 1). This study was limited to the Table 1). To stratifyby vegetationtype we overlaidtopo- northwesternquadrant of GSMNP (613 km2). Elevations graphic maps with Landsat Thematic Mapper satellite withinthe studyarea ranged from 270 m to 2,025 m. Soils imagery that was remotely sensed during 1984 are thin and poorly developed with mediumto high acid- (MacKenzie1993). This vegetationdata layer had a pixel ity, low water storagecapacity, and low to moderatefer- resolutionof 90 x 90 m, with each pixel classified as 1 of tility (Soil Survey 1945, 1953). Climate of the area has 14 vegetationtypes. We sampled9 of 14 vegetationtypes: been classified as a warm-temperate rain forest cove hardwood,xeric oak, mesic oak, mixed mesic hard- (Thorthwaite 1948). Annual precipitationranges from wood, pine, pine-oak, tulip-poplar,northern hardwood, 140 cm at lower elevations to 230 cm at higherelevations and spruce-fir. The 5 unsampledtypes (treeless, grassy (Stephens 1969). GSMNP's microclimaticdiversity rep- bald,grape thicket, heath bald, and water) comprised 2.4% resented site potentials for much of the federally owned of the study area. We did not recordstand age, but it was landin the southernAppalachians, and management goals generally>60 years.Thus, forests in most vegetationtypes of the Parkare intendedto maintainan absence of human were relativelymature and undisturbed.An exception to alteration. Thus, GSMNP affordeda unique opportunity this was the spruce-fir type, in which over 70% of the to studyhabitat use of wildlife populationsin a relatively Fraserfir (Abiesfraseri) had been killed by the balsam controlledsetting. wooly adelgid (Adelgespiceae) duringthe past 30 years (NationalPark Service [NPS] personnel,Gatlinburg, Ten- nessee, USA, personalcommunication, 1995). We clas- METHODS sified elevation rangesfor each vegetationtype as low or We selected 19 plantspecies for this studythat had been high, and aspects as northeastern(315-134?) or south- identified as primaryfoods for black bears duringprevi- western (135-314?). We distributed30-33 sample plots j 7 W j Cherokee NF Fig. 1. Location of study area in GreatSmoky MountainsNational Park, Tennessee (TN)and NorthCarolina (NC), USA. Muchof surrounding area is national forest (NF). ENERGETICPRODUCTION IN THESMOKY MOUNTAINS * Inman and Pelton 59 Table1. Vegetationtypes as classifiedby MacKenzie(1993), including dominant tree species, area,and percent of northwest quadrant of Great Smoky Mountains National Park, North Carolina and Tetnnessee, USA. a Vegetation type Dominanttree species Hectares Area (%) Covehardwood Easternhemlock (Tsuga canadensis) 14,710 24% Sweet birch (Betula lenta) Red maple (Acer rubrum) Carolinasilverbell (Halesia carolina) Tulip-poplar(Liriodendron tulipifera) Northernred oak (Quercus rubra) Basswood (Tilia heterophylla) Yellow birch (Betula alleghaniensis) Pine Table-mountainpine (Pinus pungens) 13,476 22% Pitch pine (Pinus rigida) Virginiapine (Pinus virginiana) Scarlet oak (Quercuscoccinea) Xericoak Chestnutoak (Quercusprinus) 13,235 22% Red maple Tulip-poplar Sourwood (Oxydendrumarboreum) Scarlet oak Mixedmesic hardwood Tulip-poplar 8,017 13% Red maple Easternhemlock Chestnutoak Northernhardwood Yellow birch 3,363 6% Americanbeech (Fagus grandifolia) Sweet birch Easternhemlock Red maple Northernred oak Red spruce (Picea rubens)