Evaluation of Cold—Moist Stratification Treatments for Germinating Eastern and Carolina Hemlock Seeds for ex Situ Gene Conservation Author(s): Robert M. Jetton, W. Andrew Whittier and William S. Dvorak Source: Southeastern Naturalist, 13(sp6):168-177. Published By: Eagle Hill Institute URL: http://www.bioone.org/doi/full/10.1656/058.013.s611
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BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. 2014 Forest Impacts and Ecosystem EffectsSoutheastern of the Hemlock Naturalist Woolly Adelgid in theVol. Eastern 13, Special US Issue 6 R.M. Jetton, W.A. Whittier, and W.S. Dvorak Southeastern Naturalist 6SHFLDO,VVXH ± (YDOXDWLRQRI&ROG±0RLVW6WUDWL¿FDWLRQ7UHDWPHQWVIRU *HUPLQDWLQJ(DVWHUQDQG&DUROLQD+HPORFN6HHGVIRU ([6LWX*HQH&RQVHUYDWLRQ
Robert M. Jetton1,*, W. Andrew Whittier1, and William S. Dvorak1
$EVWUDFW Populations of Tsuga canadensis (Eastern Hemlock) and Tsuga caroliniana (Carolina Hemlock) are declining due to infestation by Adelges tsugae (Hemlock Woolly Adelgid), an exotic insect pest. A better understanding of the environmental conditions UHTXLUHGIRUVHHGJHUPLQDWLRQLVQHHGHGWRPRUHHI¿FLHQWO\XWLOL]HWKHVHHGVFROOHFWHGIRU genetic-resource conservation and the establishment of seed orchards. This study examined WKHHIIHFWRIFROG±PRLVWVWUDWL¿FDWLRQWUHDWPHQWVRIYDU\LQJGXUDWLRQ DQGGD\V RQWRWDOJHUPLQDWLRQ DQGWKHQXPEHURIGD\VWR¿UVWDQGSHDNJHUPLQD- tion (germination speed) on seeds of both species in experiments conducted at 22 °C and K KOLJKW GDUNSKRWRSHULRG2YHUDOOWRWDOJHUPLQDWLRQIRU(DVWHUQ+HPORFNZDV DQGLQFUHDVHGZLWKLQFUHDVLQJGXUDWLRQRIWKHVWUDWL¿FDWLRQWUHDWPHQWV&DUROLQD+HPORFN WRWDOJHUPLQDWLRQZDVDQGYDULHGOLWWOHDPRQJWKHWUHDWPHQWVDOWKRXJKIHZHUVHHGV WHQGHG WR JHUPLQDWH IROORZLQJ ORQJHU GXUDWLRQV RI VWUDWL¿FDWLRQ 6WUDWL¿FDWLRQ LQFUHDVHG germination speed of Eastern Hemlock but not Carolina Hemlock. The results indicate WKDW(DVWHUQ+HPORFNVHHGVVKRXOGEHFROG±PRLVWVWUDWL¿HGDW&IRUDWOHDVW±GD\V prior to sowing to promote higher total germination. Carolina Hemlock seeds can be sown GLUHFWO\IROORZLQJDKVRDNZLWKQRDGGLWLRQDOFROG±PRLVWVWUDWL¿FDWLRQ
,QWURGXFWLRQ Tsuga canadensis (L.) Carr. (Eastern Hemlock) and T. caroliniana Englem. (Carolina Hemlock) are long-lived, slow-growing, shade-tolerant conifers native to eastern North America. Eastern Hemlock occurs across a broad elevation range IURPVHDOHYHOWRPDQGKDVDZLGHVSUHDGJHRJUDSKLFGLVWULEXWLRQWKDWH[WHQGV from Nova Scotia west to northern Minnesota and south through New England, the Middle Atlantic States, and the southern Appalachian Mountains into northern *HRUJLDDQGWKH&XPEHUODQG3ODWHDXRI$ODEDPD )DUMRQ 7KHVSHFLHVLVEL- modal in habitat distribution, occurring in high abundance on moist, well-drained, QXWULHQWULFK VRLOV RI PHVLF ULSDULDQ ]RQHV DQG VHDVRQDOO\ PRLVW VXE[HULF DUHDV DWWKHORZDQGPLGGOHSRUWLRQVRILWVHOHYDWLRQUDQJH .HVVHOO $WKLJKHU elevations, it is often more scattered along exposed xerophytic slopes and ridges. Carolina Hemlock has a much smaller distribution and is restricted to the south- eastern United States where it is endemic to the southern Appalachian Mountain and Upper Piedmont regions of Virginia, Tennessee, Georgia, North Carolina, and 6RXWK&DUROLQD -HWWRQHWDO 8QOLNH(DVWHUQ+HPORFN&DUROLQD+HPORFNLV
1Camcore, Department of Forestry and Environmental Resources, North Carolina State 8QLYHUVLW\&DPSXV%R[5DOHLJK1& *Corresponding author - rmjetton@ ncsu.edu. Manuscript Editor: Scott Markwith 168 2014Southeastern Naturalist Vol. 13, Special Issue 6 R.M. Jetton, W.A. Whittier, and W.S. Dvorak
PRVWDEXQGDQWDORQJGU\QRUWKIDFLQJURFN\ULGJHWRSVDWHOHYDWLRQVRI± PRQVRLOVWKDWDUHGU\DFLGLFDQGQXWULHQWSRRU +XPSKUH\ Both Eastern and Carolina Hemlocks are considered to be at-risk species, and a number of factors threaten their long-term sustainability in eastern North America %HDUGPRUHHWDO)DUMRQHWDO 7KHPRVWVHULRXVRIWKHVHWKUHDWVLV the invasive Adelges tsugae Annand (Hemlock Woolly Adelgid [HWA]), an exotic, aphid-like insect introduced from Japan into the eastern United States in the early VWKDWFXUUHQWO\LQIHVWVDSSUR[LPDWHO\RIWKH(DVWHUQ+HPORFNUDQJHDQG RIWKH&DUROLQD+HPORFNUDQJH 86'$)RUHVW6HUYLFH +:$IHHGV at the base of hemlock needles by inserting its piercing/sucking mouthparts and extracting stored nutrients from xylem ray-parenchyma, thereby disrupting vegeta- tive and reproductive bud formation, causing needle desiccation and defoliation, DQGNLOOLQJWUHHVLQ±\HDUV 0DWHULDOVDQG0HWKRGV :HFROOHFWHG ULSH VHHG FRQHV LQ 6HSWHPEHU &DUROLQD +HPORFN DQG 2FWREHU (DVWHUQ+HPORFN IURPQDWXUDOVWDQGV SHUVSHFLHV ORFDWHGLQWKHFHQWUDO and southern Appalachian Mountains of the eastern United States (Table 1). We placed seed cones into cloth bags and stored them in a dry greenhouse ven- WLODWHGWRDPELHQWFRQGLWLRQVIRUGWRIDFLOLWDWHWKHRSHQLQJRIFRQHVDQGUHOHDVH RIVHHGVIURPWKHFRQHVFDOHV .DUUIDOW $IWHUFRQHGU\LQJZHH[WUDFWHGVHHGV from the cones using a shaker box, de-winged them in a small tumbling drum, and removed empty seeds, loose wings, and chaff using a seed blower (Seedburo 0RGHO6HHGEXUR(TXLSPHQW&RPSDQ\'HV3ODLQHV,/ :HUHPRYHGPRUH HPSW\VHHGVE\FRQGXFWLQJDÀRDWWHVWLQZDWHU:HGHWHUPLQHGWKHPRLVWXUHFRQWHQW RIDVXEVHWRIVHHGVIURPHDFKVHHGORWXVLQJD0HWWOHU7ROHGRPRLVWXUHDQDO\]HU 0HWWOHU7ROHGR,QF&ROXPEXV2+ DYHUDJHVHHGPRLVWXUHFRQWHQWZDV IRU(DVWHUQ+HPORFNDQGIRU&DUROLQD+HPORFN:HSDFNDJHGWKHUHPDLQLQJ VHHGVLQVPDOOUHVHDODEOHSODVWLFEDJVDQGSODFHGWKHPLQGU\±FROGVWRUDJHDW& IRU GD\VSULRUWRWKHEHJLQQLQJRIWKHVWXG\ 3UHJHUPLQDWLRQ WUHDWPHQWV FRQVLVWHG RI FROG±PRLVW VWUDWL¿FDWLRQ KHUHDIWHU VWUDWL¿FDWLRQ RIVHHGVIRU DQGGD\VDW&LQDGDUNZDON LQFRROHU)RUVWUDWL¿FDWLRQZHVRDNHGDOOVHHGVLQGLVWLOOHGZDWHUIRUKDWURRP WHPSHUDWXUHDQGSODFHGWKHPLQ FP3HWULGLVKHVZLWKDVXEVWUDWHRIZKLWHJHUPLQD- WLRQSDSHUPRLVWHQHGWRVDWXUDWLRQZLWKGLVWLOOHGZDWHU(DFK3HWULGLVKFRQWDLQHG VHHGVDQGWKHUHZHUHGLVKHVSHUVSHFLHVWUHDWPHQWSURYHQDQFHFRPELQDWLRQIRUD WRWDORISHWULGLVKHVDQGVHHGVLQWKHVWXG\:HFKHFNHGGLVKHVGDLO\DQG Table 1. Provenance location and Hemlock Woolly Adelgid infestation status for Eastern Hemlock DQG&DUROLQD+HPORFNVHHGVRXUFHVXWLOL]HGLQWKHVHHGVWUDWL¿FDWLRQVWXG\/HDVWVTXDUHPHDQWRWDO JHUPLQDWLRQ 6( DFURVVDOOFROG±PRLVWVWUDWL¿FDWLRQWUHDWPHQWVLVDOVRUHSRUWHGIRUHDFKVHHGVRXUFH /DW ODWLWXGH 1 ORQJ ORQJLWXGH : HOHY HOHYDWLRQ P WRWDOJHUP WRWDOJHUPLQDWLRQ HWA Species/provenance County, State Lat Long Elev status Total germ Eastern Hemlock &RRN)RUHVW )RUHVW3$ 1RQH .HQWODQG)DUP 0RQWJRPHU\9$ ,QIHVWHG /DNH7R[DZD\ 7UDQV\OYDQLD1& 7UHDWHG Carolina Hemlock &DUO6DQGEXUJ +HQGHUVRQ1& 7UHDWHG +DQJLQJ5RFN 6WRNHV1& ,QIHVWHG 1HZ5LYHU 0RQWJRPHU\9$ ,QIHVWHG 170 2014Southeastern Naturalist Vol. 13, Special Issue 6 R.M. Jetton, W.A. Whittier, and W.S. Dvorak UHPRLVWHQHGWKHJHUPLQDWLRQSDSHUDVQHHGHG:HEHJDQWKHVHHGVWUDWL¿FDWLRQZLWK WKHGWUHDWPHQWDQGZRUNHGEDFNZDUGVVRWKDWDOO3HWULGLVKHVZHUHUHDG\WR start the germination period of the experiment on the same day. All seeds remained SDFNDJHGLQWKHUHVHDODEOHSODVWLFEDJVDW&XQWLOSODFHGLQWRWKHLUSDUWLFXODU VWUDWL¿FDWLRQWUHDWPHQWV7KHUHIRUHVHHGVIRUHDFKWUHDWPHQWH[SHULHQFHGGLIIHUHQW OHQJWKVRIGU\±FROGVWRUDJHIRUH[DPSOH GD\VIRUWKHGVWUDWL¿FDWLRQWUHDW- PHQWDQGGD\VIRUWKHGD\WUHDWPHQW We conducted the VHHGJHUPLQDWLRQ H[SHULPHQW RYHU D GD\ SHULRG LQ DQ environmental chamber at the North Carolina State University Southeastern Plant Environment Laboratory (Phytotron). Environmental conditions in the chamber ZHUHDFRQVWDQWWHPSHUDWXUHRI&±UHODWLYHKXPLGLW\DQG OLJKW± GDUNSKRWRSHULRGOLWE\DFRPELQDWLRQRIÀXRUHVFHQWDQGLQFDQGHVFHQWEXOEVWKDW SURYLGHGDSSUR[LPDWHO\NO[RILOOXPLQDWLRQ:HSODFHG3HWULGLVKHVRQWZR shelves inside the chamber with two blocks of dishes per shelf. Each block con- tained 1 Petri dish per species/provenance/treatment combination. We remoistened the dishes with distilled water daily during the germination period of the experi- ment. During daily inspection, we recorded the number of newly germinated seeds LQHDFKGLVK:HFODVVL¿HGVHHGVDVJHUPLQDWHGZKHQWKHHPHUJLQJUDGLFOHZDV PPORQJ$WWKHHQGRIWKHGJHUPLQDWLRQSHULRGZHFDOFXODWHGWKHWRWDOQXPEHU RIVHHGVJHUPLQDWHGDQGWKHQXPEHURIGD\VWR¿UVWDQGSHDNJHUPLQDWLRQIRUHDFK Petri dish in the experiment. 6WDWLVWLFDO DQDO\VLV :HDQDO\]HGWKHJHUPLQDWLRQGDWDIRU(DVWHUQ+HPORFNDQG&DUROLQD+HPORFN seeds using a logistic regression model with a binomial distribution and logit OLQNIXQFWLRQLQWKH*/,00,;SURFHGXUHRI6$6 6$6 WRHYDOXDWHWKH SUREDELOLW\ RI VHHG JHUPLQDWLRQ DIWHU GD\V 7KH UHVSRQVH YDULDEOH ZDV WRWDO SHUFHQW JHUPLQDWLRQ KHUHDIWHU UHIHUUHG WR DV WRWDO JHUPLQDWLRQ GH¿QHG LQ WKH model statement by the events/trials syntax or the number of germinated seeds per petri dish/total seeds per petri dish. The model tested the main effects of block, VSHFLHVSURYHQDQFH VSHFLHV DQGVWUDWL¿FDWLRQDQGDOOWZRZD\LQWHUDFWLRQVRQ total germination. To investigate within-species variation, we used similar logistic UHJUHVVLRQ PRGHOV WR WHVW WKH PDLQ HIIHFWV RI EORFN SURYHQDQFH DQG VWUDWL¿FD- tion, and all two-way LQWHUDFWLRQVRQWKHSUREDELOLW\RIVHHGJHUPLQDWLRQDIWHU days for each species individually. We conducted analysis of variance using the */0SURFHGXUHRI6$6 WRDQDO\]HWKHQXPEHURIGD\VWR¿UVWJHUPLQDWLRQDQG peak germination for the species individually, testing the main effects of block, SURYHQDQFH VWUDWL¿FDWLRQ DQG DOO WZRZD\ LQWHUDFWLRQV$OO PHDQV UHSRUWHG DUH OHDVWVTXDUHPHDQV$OOYDULDQFHVUHSRUWHGDUHVWDQGDUGHUURUV2QO\VLJQL¿FDQWHI- fects from the analysis are reported in the results. 5HVXOWV 2I WKH (DVWHUQ +HPORFN DQG &DUROLQD +HPORFN VHHGV DVVHVVHG LQ WKLV VWXG\RUJHUPLQDWHGVXFFHVVIXOO\E\WKHHQGRIWKHGH[SHULPHQW7KH 171 2014 Southeastern Naturalist Vol. 13, Special Issue 6 R.M. Jetton, W.A. Whittier, and W.S. Dvorak logistic regression analysis including species as a main effect indicated that strati- ¿FDWLRQ P VSHFLHV P SURYHQDQFH VSHFLHV P < DQGWKHLQWHUDFWLRQRIVSHFLHV VWUDWL¿FDWLRQ P VLJQL¿FDQWO\DIIHFWHGWKH probability of seed germination. Total germination was higher for Eastern Hem- ORFN FRPSDUHGWR&DUROLQD+HPORFN DQGUDQJHGIURP ±DPRQJWKHSURYHQDQFHV 7DEOH 7KHSURYHQDQFHVZLWKWKHKLJKHVW total germination were either uninfested or had received insecticide treatments in WKH¿HOGWRFRQWURO+:$7KHSURYHQDQFHVZLWKWKHORZHVWJHUPLQDWLRQZHUH HWA-infested at the time of seed collection. 7KH SUREDELOLW\ RI VHHG JHUPLQDWLRQ IRU (DVWHUQ +HPORFN ZDV VLJQL¿FDQW- O\ DIIHFWHG E\ VWUDWL¿FDWLRQ P SURYHQDQFH P DQG WKH SURYHQDQFH VWUDWL¿FDWLRQLQWHUDFWLRQ P 7KHRYHUDOOVSHFLHVWUHQGZDV IRULQFUHDVLQJWRWDOJHUPLQDWLRQZLWKLQFUHDVLQJGXUDWLRQRIWKHVWUDWL¿FDWLRQWUHDW- ments (Fig. 1). We also observed this trend for the individual provenances, although the slope of increase for the Kentland Farm seed-source was much lower than that for the other 2 populations. Total germination of seeds from the Kentland Farm SRSXODWLRQZDVZKLFKZDVDQGORZHUWKDQVHHGVIURPWKH&RRN)RUHVW and Lake Toxaway populations, respectively (Table 1). Figure. 1. Least square mean (± SE) total-germination response of Eastern Hemlock seed to FROG±PRLVWVWUDWL¿FDWLRQWUHDWPHQWVDWWKHVSHFLHV RYHUDOO DQGLQGLYLGXDOSURYHQDQFHOHYHOV 172 2014Southeastern Naturalist Vol. 13, Special Issue 6 R.M. Jetton, W.A. Whittier, and W.S. Dvorak 6HHGJHUPLQDWLRQIRU&DUROLQD+HPORFNZDVVLJQL¿FDQWO\DIIHFWHGE\VWUDWL¿FD- tion (P DQGSURYHQDQFH P DQGWKHUHZDVPXFKOHVVYDULDWLRQ LQ WRWDO JHUPLQDWLRQ DPRQJ WKH VWUDWL¿FDWLRQ WUHDWPHQWV FRPSDUHG WR (DVWHUQ +HPORFN*HUPLQDWLRQYDULHGOLWWOHIURP±GD\VDQGWKHQGHFUHDVHGIROORZ- LQJWKH DQGGWUHDWPHQWV )LJ 7KHWHQGHQF\RIWRWDOJHUPLQDWLRQWR GHFUHDVHIROORZLQJWKHORQJHUGXUDWLRQVWUDWL¿FDWLRQWUHDWPHQWVZDVDSSDUHQWIRU the individual provenances as well. Total germination among seeds from the Carl 6DQGEXUJSRSXODWLRQZDVKLJKHUWKDQIRUVHHGVIURP+DQJLQJ5RFNDQG1HZ River (Table 1). The speed of Eastern Hemlock and Carolina Hemlock seed germination was VLJQL¿FDQWO\ LQÀXHQFHG E\ WKH VWUDWL¿FDWLRQ WUHDWPHQW DQG SURYHQDQFH DV ZHOO 2YHUDOO&DUROLQD+HPORFNVHHGVJHUPLQDWHG¿UVWDQGUHDFKHGSHDNJHUPLQDWLRQ VRRQHU GDQGGUHVSHFWLYHO\ FRPSDUHGWR(DVWHUQ+HPORFN GDQGGUHVSHFWLYHO\ $OWKRXJKRYHUDOOJHUPLQDWLRQVSHHG LQ(DVWHUQ+HPORFNZDVVORZHUVWUDWL¿FDWLRQLPSURYHGWKHSDFHRIJHUPLQDWLRQLQ WKLVVSHFLHV$PRQJ(DVWHUQ+HPORFNVHHGVWKHQXPEHURIGD\VWR¿UVWJHUPLQDWLRQ ZDVVLJQL¿FDQWO\DIIHFWHGE\ERWKVWUDWL¿FDWLRQDQGSURYHQDQFH P < ZKLOH WKHQXPEHURIGD\VWRSHDNJHUPLQDWLRQZDVDIIHFWHGE\VWUDWL¿FDWLRQDORQH P = $VWKHGXUDWLRQRIWKHVWUDWL¿FDWLRQWUHDWPHQWVLQFUHDVHGLWWRRNIHZHU GD\VWRDWWDLQERWK¿UVWDQGSHDNJHUPLQDWLRQ 7DEOH $PRQJWKHSURYHQDQFHV WKH .HQWODQG )DUP VHHG VRXUFH WRRN ORQJHU WR UHDFK ¿UVW DQG SHDN JHUPLQDWLRQ compared to Cook Forest and Lake Toxaway. /LNH(DVWHUQ+HPORFNWKHQXPEHURIGD\VWR¿UVWJHUPLQDWLRQLQ&DUROLQD+HP- ORFNZDVDOVRVLJQL¿FDQWO\DIIHFWHGE\VWUDWL¿FDWLRQ P DQGSURYHQDQFH (P +RZHYHUZHREVHUYHGWKHRSSRVLWHUHVSRQVHWRVWUDWL¿FDWLRQ WKH QXPEHURIGD\VWR¿UVWJHUPLQDWLRQLQFUHDVHGVOLJKWO\ZLWKLQFUHDVLQJGXUDWLRQRI VWUDWL¿FDWLRQ 7DEOH 7KHQXPEHURIGD\VWRSHDNJHUPLQDWLRQZDVVLJQL¿FDQWO\ Figure. 2. Least square mean (± SE) total-germination response of Carolina Hemlock seed to FROG±PRLVWVWUDWL¿FDWLRQWUHDWPHQWVDWWKHVSHFLHV RYHUDOO DQGLQGLYLGXDOSURYHQDQFHOHYHOV 173 2014 Southeastern Naturalist Vol. 13, Special Issue 6 R.M. Jetton, W.A. Whittier, and W.S. Dvorak affected by provenance (P ZLWKWKH&DUO6DQGEXUJVHHGVRXUFHWDNLQJWKH IHZHVWGD\VWRUHDFK¿UVWJHUPLQDWLRQDQGWKHPRVWGD\VWRUHDFKSHDNJHUPLQDWLRQ (Table 2). 'LVFXVVLRQ 7KHRYHUDOOWRWDOJHUPLQDWLRQRIUHSRUWHGLQWKLVVWXG\LVZLWKLQWKHH[SHFW- HGUDQJH ± IRUVHHGVIURPQDWXUDOVWDQGVRI(DVWHUQ+HPORFNDQG&DUROLQD +HPORFN *RGPDQ DQG /DQFDVWHU -HWWRQ HW DO 7RWDO VSHFLHVOHYHO JHUPLQDWLRQRIDQGLVFRQVLVWHQWZLWKWKHUHVXOWVRIJHUPLQDWLRQWHVWVFRQ- GXFWHGRQDQGQDWXUDOVWDQGVHHGVRXUFHVRI(DVWHUQ+HPORFNDQG&DUROLQD Hemlock, respectively, that have been collected for genetic-resource conservation -HWWRQHWDO 7KHVHOHYHOVRIVHHGJHUPLQDWLRQDUHORZHUWKDQWKRVHH[SHFWHG for the 2 other hemlock species native to North America, Western Hemlock and 0RXQWDLQ +HPORFN ZKHUH QDWXUDOVWDQG VHHG JHUPLQDWLRQ RI ± LV W\SLFDO 0HDQV 3DFNHH Eastern Hemlock and Carolina Hemlock are sympatric species in the southern Appalachian Mountains, and many silvicultural descriptions have historically lumped the two species together, leaving the reader to assume them to be similar in PRVWDVSHFWVRIWKHLUELRORJ\ HJ*RGPDQDQG/DQFDVWHU +RZHYHUXQGHU the experimental conditions tested here, in terms of total germination and germina- tion speed, seeds of these 2 hemlock species demonstrated substantially different UHVSRQVHVWRWKHFROG±PRLVWVWUDWL¿FDWLRQWUHDWPHQWV6WUDWL¿FDWLRQJHQHUDOO\LP- proved the germination of Eastern Hemlock seeds, and the amount of improvement Table 2. /HDVWVTXDUHPHDQ 6( QXPEHURIGD\VWR¿UVWJHUPLQDWLRQDQGSHDNJHUPLQDWLRQIRU(DVW- HUQ+HPORFNDQG&DUROLQD+HPORFNVHHGVDPRQJWKHFROG±PRLVWVWUDWL¿FDWLRQ &06 WUHDWPHQWV LQ GD\VRIVWUDWL¿FDWLRQ DQGSURYHQDQFHV 'D\VWR¿UVWJHUPLQDWLRQ 'D\VWRSHDNJHUPLQDWLRQ Eastern Hemlock Carolina Hemlock Eastern Hemlock Carolina Hemlock CMS treatment Provenance &RRN)RUHVW .HQWODQG)DUP /DNH7R[DZD\ &DUO6DQGEXUJ +DQJLQJ5RFN 1HZ5LYHU 174 2014Southeastern Naturalist Vol. 13, Special Issue 6 R.M. Jetton, W.A. Whittier, and W.S. Dvorak in both total germination and germination speed increased with increasing duration RIWKHVWUDWL¿FDWLRQWUHDWPHQWV%\FRPSDULVRQWRWDOJHUPLQDWLRQRI&DUROLQD+HP- ORFNVHHGYDULHGOHVVDPRQJWKHVWUDWL¿FDWLRQWUHDWPHQWVDQGWHQGHGWRGHFUHDVH VOLJKWO\IROORZLQJWKHORQJHUGXUDWLRQVRIVWUDWL¿FDWLRQ DQGG 7KHIDYRUDEOHUHVSRQVHRI(DVWHUQ+HPORFNVHHGJHUPLQDWLRQWRVWUDWL¿FDWLRQ is consistent with previous studies on this species as well as those with Western +HPORFN6WUDWL¿FDWLRQRI(DVWHUQ+HPORFNVHHGVLQFROG±PRLVWSHDWIRU± GD\VLPSURYHGERWKWRWDOJHUPLQDWLRQ DQGJHUPLQDWLRQUDWH GD\VWRJHU- PLQDWLRQ %DOGZLQ 6WHDUQVDQG2OVRQ ,QVWXGLHVZLWK:HVWHUQ +HPORFNFROGVWUDWL¿FDWLRQSHULRGVRI±GD\VLPSURYHGERWKWRWDOJHUPLQDWLRQ DQGJHUPLQDWLRQUDWH $OOHQ /LDQG%XUWRQ RUJHUPLQDWLRQUDWHDORQH (GZDUGV (GZDUGV DQG 2OVHQ 7KH UHVSRQVH RI &DUROLQD +HPORFN VHHGV WR VWUDWL¿FDWLRQ WUHDWPHQWV LV VLPLODU WR ZKDW LV NQRZQ IURP VWXGLHV ZLWK 0RXQWDLQ +HPORFN ZKHUH VHHG VWUDWL¿FDWLRQ KDG QR PHDQLQJIXO HIIHFW RQ WRWDO JHUPLQDWLRQ (GZDUGV DQG (O.DVVDE\ (O.DVVDE\ DQG (GZDUGV +RZHYHU(GZDUGVDQG(O.DVVDE\ IRXQGWKDWVWUDWL¿FDWLRQLPSURYHGWKH germination rate of Mountain Hemlock seeds, while in the present study Carolina +HPORFN VHHG JHUPLQDWLRQ VSHHG ZDV UHODWLYHO\ XQDIIHFWHG E\ VWUDWL¿FDWLRQ DQG HYHQVOLJKWO\VORZHULQGD\VWR¿UVWJHUPLQDWLRQ This experiment was designed to understand how differing lengths of cold– PRLVWVWUDWL¿FDWLRQDIIHFW(DVWHUQDQG&DUROLQD+HPORFNVHHGJHUPLQDWLRQUDWHV We did not address why the species and provenances responded to the treatments in the manner they did, but the data do suggest several interesting questions for future VWXGLHV )LUVW DUH WKH VSHFLHVOHYHO VHHGJHUPLQDWLRQ UHVSRQVHV WR PRLVW VWUDWL¿- cation related to the soil moisture conditions experienced by the species in their W\SLFDOKDELWDWV"(DVWHUQ+HPORFNW\SLFDOO\LQKDELWVPRLVWVRLOV .HVVHOO DQG LWUHVSRQGHGIDYRUDEO\WRVWUDWL¿FDWLRQZKLOH&DUROLQD+HPORFNW\SLFDOO\LQKDELWV GU\VRLOVDQGLWVKRZHGOLWWOHUHVSRQVHWRFROG±PRLVWVWUDWL¿FDWLRQ +XPSKUH\ Second, are seed germination responses controlled at the population level and de- WHUPLQHGE\WKHFOLPDWHVRLOPRLVWXUHFRQGLWLRQVHIIHFWLYHSRSXODWLRQVL]HVDQG pollen loads experienced by trees in the individual provenances? Any one of these factors might explain why the Kentland Farm population had a much more muted UHVSRQVHWRFROG±PRLVWVWUDWL¿FDWLRQFRPSDUHGWRWKHRWKHU(DVWHUQ+HPORFNVHHG VRXUFHV6HHGVRXUFHGLIIHUHQFHVKDYHEHHQVKRZQWRKDYHVLJQL¿FDQWLQÀXHQFHRQ VHHGJHUPLQDWLRQLQ0RXQWDLQ+HPORFN (O.DVVDE\DQG(GZDUGV )LQDOO\ KRZPLJKW+:$LQIHVWDWLRQDQGVRLOLQVHFWLFLGHLQMHFWLRQVLQÀXHQFHÀRZHULQJVHHG set, and subsequent seed germination in Eastern Hemlock and Carolina Hemlock? %RWKDUHOLNHO\WRKDYHVLJQL¿FDQWLPSOLFDWLRQVIRUWKHTXDOLW\RIVHHGVFROOHFWHG for genetic-resource conservation programs, the development of soil seedbanks, and the potential for natural stand regeneration following large-scale HWA-related decline and mortality. Further research is also needed to better understand how the germination of Eastern Hemlock and Carolina Hemlock seeds might differ under varying 175 2014 Southeastern Naturalist Vol. 13, Special Issue 6 R.M. Jetton, W.A. Whittier, and W.S. Dvorak temperature and photoperiod regimes. For example, the germination rate of Western Hemlock seeds benefits from photoperiod regimes with relatively short KRXUOLJKWSHULRGV (GZDUGVDQG2OVHQ DQGWRWDOJHUPLQDWLRQDQGJHU- mination rate of Mountain Hemlock seeds is best under alternating temperature UHJLPHVRI DQG &RQDFRPSOHPHQWDU\ / 'SKRWRSHULRG (O .DVVDE\DQG(GZDUGV 6WHDUQVDQG2OVRQ IRXQGWKDWWKHJHUPLQD- tion of Eastern Hemlock seed varies considerably with both temperature and photoperiod, and that the most favorable photoperiod depends on the temperature under which germination is carried out. Based on the data available from this study, we suggest the following for stratifying seeds of Eastern Hemlock and Carolina Hemlock prior to sowing and JHUPLQDWLQJVHHGVDW&XQGHUD / 'SKRWRSHULRG)ROORZLQJDKRXU ZDWHUVRDN(DVWHUQ+HPORFNVHHGVVKRXOGEHFROG±PRLVWVWUDWL¿HGDW&IRUDW OHDVW±GSULRUWRVRZLQJWRSURPRWHKLJKHUWRWDOJHUPLQDWLRQUHFRJQL]LQJWKDW DOWKRXJKLWPD\QRWEHRSHUDWLRQDOO\HI¿FLHQWDQDGGLWLRQDO±LPSURYHPHQW LQJHUPLQDWLRQPD\EHDFKLHYHGZLWKVWUDWL¿FDWLRQSHULRGVRI ±G&DUROLQD +HPORFNVHHGVFDQEHVRZQGLUHFWO\IROORZLQJDKRXUVRDNZLWKQRDGGLWLRQDO FROG±PRLVWVWUDWL¿FDWLRQDOWKRXJKWRWDOJHUPLQDWLRQRIVRPHVHHGORWVPD\LPSURYH VOLJKWO\IROORZLQJGD\VRIVWUDWL¿FDWLRQ/RQJHUVWUDWL¿FDWLRQSHULRGVDSSHDUWR decrease germination in Carolina Hemlock and should be avoided. $FNQRZOHGJPHQWV 7KHDXWKRUVZRXOGOLNHWRWKDQN7LP)URQW] 3$%XUHDXRI)RUHVWU\&RRN)RUHVW ,UHQH van Hoff (National Park Service, Carl Sandburg National Historic Site, Flatrock, NC), Tom McAvoy (VA Tech, Kentland Farm and New River, Blacksburg, VA), and the Minnick )DPLO\ /DNH7R[DZD\1& IRUKHOSLQJWRDUUDQJHVHHGFROOHFWLRQV &DUROH6DUDYLW]-DQHW 6KXUWOHIIDQGWKH1&683K\WRWURQVWDIIIRUXVHRIWKHLUIDFLOLW\ *DU\+RGJHDQG-RKQ )UDPSWRQ IRU VWDWLVWLFDO JXLGDQFH DQG WZR DQRQ\PRXV UHYLHZHUV ZKRVH FRPPHQWV DQG suggestions greatly improved the manuscript. This work was supported by USDA Forest 6HUYLFHJUDQWDJUHHPHQW '*DQG&DPFRUHUHVHDUFKSURMHFW /LWHUDWXUH &LWHG $OOHQ*6 )DFWRUVDIIHFWLQJWKHYLDELOLW\DQGJHUPLQDWLRQEHKDYLRURIFRQLIHURXV VHHG 3DUW&RQHDQGVHHGPDWXULW\Tsuga heterophylla (Rafn.) Sarg. The Forestry &KURQLFOH ± %DOGZLQ+, 7KHHIIHFWRIDIWHUULSHQLQJWUHDWPHQWRQWKHJHUPLQDWLRQRI(DVWHUQ +HPORFNVHHG-RXUQDORI)RUHVWU\ ± %DOGZLQ+, )XUWKHUQRWHVRQWKHJHUPLQDWLRQRIKHPORFNVHHG-RXUQDORI)RUHVWU\ ± %DUERXU-55+5XWKDQG53.DUUIDOWTsuga&DUUKHPORFN3S± In F.T. Bonner and R.P. Karrfalt (Eds.). The Woody Plant Seed Manual. USDA Forest Service Agriculture Handbook 727. Washington, DC. %HDUGPRUH7-/RR%0F$IHH&0DORXLQDQG'6LPSVRQ$VXUYH\RIWUHH VSHFLHVRIFRQFHUQLQ&DQDGD 7KHUROHIRUJHQHWLFFRQVHUYDWLRQ7KH)RUHVWU\&KURQLFOH ± 176 2014Southeastern Naturalist Vol. 13, Special Issue 6 R.M. Jetton, W.A. Whittier, and W.S. Dvorak (GZDUGV'*: (IIHFWVRIVWUDWL¿FDWLRQRQ:HVWHUQ+HPORFNJHUPLQDWLRQ&DQD- dian Journal of Forest Research ± (GZDUGV '*: DQG<$ (O.DVVDE\ 7KH HIIHFW RI VWUDWL¿FDWLRQ DQG DUWL¿FLDO light on the germination of Mountain Hemlock seeds. Seed Science and Technology ± (GZDUGV'*:DQG3(2OVHQ $SKRWRSHULRGUHVSRQVHLQJHUPLQDWLRQRI:HVWHUQ +HPORFNVHHGV&DQDGLDQ-RXUQDORI)RUHVW5HVHDUFK ± (O.DVVDE\<$DQG'*:(GZDUGV*HUPLQDWLRQHFRORJ\LQ0RXQWDLQ+HPORFN (Tsuga mertensiana %RQJ &DUU )RUHVW(FRORJ\DQG0DQDJHPHQW ± )DUMRQ$ 3LQDFHDH'UDZLQJVDQGGHVFULSWLRQVRIWKHJHQHUDAbies, Cedrus, Pseu- dolarix, Keteleeria, Nothotsuga, Tsuga, Cathaya, Pseudotsuga, Larix, and Picea.RHOW] 6FLHQWL¿F%RRNV.RQLJVWHLQ*HUPDQ\ )DUMRQ$&13DJHDQG16FKHOOHYLV $SUHOLPLQDU\ZRUOGOLVWRIWKUHDWHQHGFR- QLIHUWD[D%LRGLYHUVLW\DQG&RQVHUYDWLRQ ± *RGPDQ50DQG./DQFDVWHU Tsuga canadensis (L.) Carr., Eastern Hemlock. 3S±In R.M. Burns and B.H. Honkala (Eds.). Silvics of North America Vol. 1. &RQLIHUV86'$)RUHVW6HUYLFH$JULFXOWXUH+DQGERRN Washington, DC. +XPSKUH\/' /LIHKLVWRU\WUDLWVRITsuga caroliniana Engelm. (Carolina Hemlock) DQGLWVUROHLQFRPPXQLW\G\QDPLFV&DVWDQHD ± -HWWRQ50:6'YRUDNDQG:$:KLWWLHU(FRORJLFDODQGJHQHWLFIDFWRUVWKDW GH¿QHWKHQDWXUDOGLVWULEXWLRQRI&DUROLQD+HPORFNLQWKHVRXWKHDVWHUQ8QLWHG6WDWHV DQGWKHLUUROHLQH[VLWXFRQVHUYDWLRQ)RUHVW(FRORJ\DQG0DQDJHPHQW ± -HWWRQ50:$:KLWWLHU:6'YRUDNDQG-5KHD&RQVHUYHGH[VLWXJHQHWLFUH- VRXUFHVRI(DVWHUQDQG&DUROLQD+HPORFN (DVWHUQ1RUWK$PHULFDQFRQLIHUVWKUHDWHQHG E\WKH+HPORFN:RROO\$GHOJLG7UHH3ODQWHUV¶1RWHV ± .DUUIDOW536HHGKDUYHVWLQJDQGFRQGLWLRQLQJ3S±In F.T. Bonner and R.P. Karrfalt (Eds.). The Woody Plant Seed Manual. USDA Forest Service Agriculture Hand- book 727. Washington, DC. .HVVHOO65 $GDSWDWLRQDQGGLPRUSKLVPLQ(DVWHUQ+HPORFNTsuga canadensis (L.) Carr. American Naturalist ± /L;-DQG3-%XUWRQ ,QWHUDFWLYHHIIHFWVRIOLJKWDQGVWUDWL¿FDWLRQRQWKHJHUPL- QDWLRQRIVRPH%ULWLVK&ROXPELDFRQLIHUV&DQDGLDQ-RXUQDORI%RWDQ\ ± 0HDQV-( Tsuga mertensiana %RQJ &DUU0RXQWDLQ+HPORFN3S±In R.M. Burns and B.H. Honkala (Eds.). Silvics of North America Vol. 1. Conifers. USDA )RUHVW6HUYLFH$JULFXOWXUH+DQGERRN Washington, DC. 3DFNHH (& Tsuga heterophylla 5DI 6DUJ:HVWHUQ +HPORFN 3S ± In R.M. Burns and B.H. Honkala (Eds.). Silvics of North America Vol. 1. Conifers. USDA )RUHVW6HUYLFH$JULFXOWXUH+DQGERRN Washington, DC. 6$6,QVWLWXWH7KH6$66\VWHPIRU:LQGRZV9HUVLRQ &DU\1& 6WHDUQV)DQG-2OVRQ ,QWHUDFWLRQVRISKRWRSHULRGDQGWHPSHUDWXUHDIIHFWLQJVHHG germination in Tsuga canadensis$PHULFDQ-RXUQDORI%RWDQ\ ± 86'$)RUHVW6HUYLFH&RXQWLHVZLWKHVWDEOLVKHG+:$3RSXODWLRQV$YDLODEOH RQOLQHDWKWWS QDIVIHGXVIKSKZDPDSVSGI$FFHVVHG1RYHPEHU 177