Klein, William 5 H 639,92 followup A u s999 survey of winter injury in the forests of Montana, 1990 COOPERATIVE FORESTRY, TIMBER, MANAGEMENT AND PEST A Followup Survey of Winter Injury Montana, 990 the Forests of 1 in STATE DOCUWiE.iTo uJi-t-uCit William H. Klein, Entomologist -too' 1 Nancy Campbell, Entomologist J. MONTANA STATE LIBRARY ici5 E. 6th AVE, MONTANA 59C HELENA, S® Pia A Icrasssaa wg?. 1&S sfT. ?s•i! 1S3, ih Pr?uJ': L i I; J 1 I fc Cel 3 a I USDA, Forest Service Northern Region Report 91-03 April 1991 MONTANASTATELIBRARY Report 91-03 A FOLLOWUP SURVEY OF WINTER INJURY IN THE FORESTS OF MONTANA, 1990 by William H. Klein, Entomologist and Nancy J. Campbell, Entomologist INTRODUCTION This report isthesecond in aseriesofsurveystoattempttoevaluatesomeofthe effects ofseverewinterweather on coniferous stands in Montana. The initial survey was conducted inthesummerandfall of 1989, and reported in January 19901. That report explained in detail the survey methods and procedures, some of which will be summarily mentioned in this report. BACKGROUND During late January and early February 1989, an arctic continental air mass containing extremely low tempera- tures moved into Montana and portions of other Northern Rocky Mountain States. Immediately preceeding this arctic air intrusion, Montana and portions of neighboring states experienced an unseasonal warming trend which probably preconditioned many trees to the damage that followed. Additionally, 3 consecutive years of drought (1986 to 1988) could well have further decreased the trees’ resistance to severe physiological stress. Most of the damage occurred in mature and overmature lodgepole pine stands east of the Continental Divide in portions of the Helena, Deerlodge, and Lewis and Clark National Forests. Conspicuous, but less severe damage, occurred in parts of other National Forests west of the Divide, including the Flathead National Forest. Besides lodgepole pine, practically all conifers were affected to varying degrees in limited locales; species affected include ponderosa pine, Douglas-fir, Engelmannspruce, western larch, subalpinefir, andwesternwhite pine. Many fruit orchards, particularly in the Flathead Valley, as well as ornamental trees and shrubs in urban and suburban areas, were badly damaged or killed outright. The pattern or nature of this widespread winter damage did not fit the "red belt" pattern; damage seemed to occur without respect to elevation, aspect, or topographic position. Duringthe spring and summer of 1989, crowns ofthe injured trees began to discolor. Aerial sketchmap surveys were done by Zone and Regional personnel to locate, identify, and record visible damage. These findings set the stage for this survey. ’Klein, William H. 1990. A Survey ofWinterDamageinthe ForestsofMontana, 1989. USDA, ForestService; Northern Region; Missoula, MT. Report 90-6, 11 pp., illustrated. A Followup Survey ofWinter Injury In the Forests ofMontana, 1990 METHODS During the summer and fall of 1989, three types of surveys were done in some of the most heavily damaged areas, as detected and delimited by the aerial reconnaissance teams. Stand Damage Assessment Surveys provided ready estimates of overall tree damage in local areas. Once located, atransect orseries of paralleltransectswererunthroughthestandswith observations made offive-tree groups at periodic intervals, usually 2 or more chains. Each tree crown was observed with binoculars and classified asto degree of damage and presence or absence of new growth. One hundred trees were observed and rated in each area. The trees were not tagged for re-examination. Individual crown condition was classified into four general categories, depending on the percent of crowns containing either green or damaged (discolored) foliage, as follows: (1) < 25 percent; (2) 26 to 50 percent; (3) 51 to 75 percent; (4) > 76 percent. Some examples of how the trees were recorded by live to dead crown ratio follow: 1. A crown completely green: 4,0, since more than 76 percent of the crown is live (4) and there are no dead (0) needles. Similarly, a crown completely dead would be rated 0,4. 2. A crown estimated to be approximately 30 percent green with the remaining part (70 percent) dead: 2,3, since more than 26 percent of the crown is alive (2) and between 51 and 75 percent of the crown is dead (3). 3. A crown estimated to be 50 percent green would be rated 2,2. Stand Re-examination Surveys provide a followup to the eventual condition ofwinter-injured trees over time. In each area, 25 trees were selected to represent a range of damage conditions, but in many ofthe badly affected areas, this was not always possible. Each tree was individually observed and judged using the above criteria, and marked with metal tags for relocation and re-examination at a later date. Photo Plots were established to provide a visual record of trees showing winter injury in 1989 and subsequent changes in appearance and condition that might follow. Plot centers were marked with stakes, and the scene replicated in 1990 by matching it with a photo print from the initial survey. FINDINGS AND OBSERVATIONS Some of the more relevant findings of the initial 1989 survey follow: 1. Mature and overmature iodgepole pine appeared to suffer the heaviest crown damage; conse- quently, those trees receiving the higher damage estimates were not expected to survive beyond 1990. Trees along stand openings were more heavily damaged than trees within the stand (Figure 1.). 2 A Followup SurveyofWinter Injury In the Forests ofMontana, 1990 Figure 1.--Lodgepole pines adjacent to openings suffered heavierdamagethanthose within the stand. Damage in 1989 (above) and 1990 (below). Note almost complete recovery of lodgepole saplings in the reproduction area. 3 A Followup Survey of Winter Injury in the Forests of Montana, 1990 Digitized by the Internet Archive 2016 in https://archive.org/details/followupsurveyof1991klei 2. What little new growth observed wasdelayed, andthoughttobeasign ofstress ratherthan survival. 3. Bark beetles, in particular the mountain pine beetle in lodgepole pine, were not considered a significant future problem in the injured stands. Western spruce budworm populations in damaged Douglas-fir stands were expected to decrease, since their food supply was severely limited. 4. More definitive information on tree condition and survival would be obtained in 1990 by revisiting the re-examination and photo plots. Stand assessment plots were not revisited, since the trees were not permanently marked and could not be accurately relocated. In early September 1990, all seven re-examination plots were revisited, and each tree was observed with binoculars and classified as in 1989 as to crown condition and presence of new growth. All photo plots, with only one exception, were located and rephotographed. Table 1. shows the changes in crown and tree condition as recorded in the seven re-examination plots in 1989 and 1990. As expected, lodgepolepineexperiencedtheheaviestmortality. Seventy-fivepercentofthe lodgepole pine on these plots were dead in 1990, even though most had exhibited some new growth in 1989. Almost half of the spruce and Douglas-fir died in 1990, but western white pine, even though receiving high damage estimates in 1989, i.e., 1,3 and 1,4, appeared to completely recover in 1990. Somewhat surprising, a few lodgepole pines (Bryan Creek, Bullion Park, and Granite Butte) with mostly green crowns and having some new growth, either deteriorated or died in 1990. The above survivor/mortality ratios can be extrapolated to representthe conditions ofthetrees examined in the stand assessment plots in 1989, with reasonable confidence. In all plots and with all species, with the exception of western white pine, the presence of new growth in late 1989 did not portend survival. It was apparent during the 1990 followup survey, particularly in the lodgepole pine stands, that even the most severely injured trees showed some resurgence of activity in 1990 in the form of both vegetative and reproduc- tive buds. Most of the new growth was in the upper reaches of the crown, and in many cases there was a proliferation of immature cones. This was most evident in lodgepole pine, since they retained most of their needles while Douglas-fir and Engelmann spruce did not. Both needles and cones appeared to reach their maximum annual growth, indicating that many were dying or had died upon cessation of the normal growing season. An interesting and, heretofore, unreported phenomenon was noticed in two lodgepole stands and in the Engelmann spruce stands. With both species, the outer bark of the lower boles of the dead trees appeared stained and upon closer examination, were, in sometrees, damptothetouch. With some lodgepoles, a hatchet chop would produce a stream of liquid. The boles of other lodgepoles produced a milky exudate having the consistency of soft custard (Figure 2.). This phenomenon helped supportthe conjecturethatthe distressedtrees, priorto death, produced new growth in the spring since photosynthesis and transpiration (evaporation) are necessary to produce whatever forces are requiredtotransport watertothe uppermost regions ofthe crown; remembering also, that many ofthe trees had little or almost no green crowns in 1989. Once transpiration ceases, the water column is broken, gravity takes over, and the column descends under its own weight through the xylem with the greatest pressure (both 4 A Followup Survey of Winter Injury In the Forests ofMontana, 1990 © >s b C©D •c5. »- w « cCo" c 5 1 ^ S§ v- a | ® w £ i CsD 3 CCDO 8 £ 0 1990. i2 CD CD CD & *2 §* and 2o co *- in ^ 2 5 t- CD CM CM li s 1 1989 <1> o 2 -s > 8 CO CM i— O’ co «- co *- in in Rl CM T- CM 1— CM CM during "o made 3<o°-‘m- O o 8 8 O’ CM CM CM conifers inOCDOCMOCMOCMC0*-O damaged CD o o O O o o C'- co in CO CO (1989) o o o o o o o o o o o o o co-£ o>~ I % z f'-CMCMr-CDOCOO’CDCMCOCOCOCM winter- (X oooooooooooooo CM d> o> of (0 E <H aC0 CO COOOCMCMOO-CDCOr-CO pine. c growth J 6O CO OOOOCMOOCMCOOCO white CMCM*— new OOOOOOOOOOOOOO Western o and *T = WP X> mortality, « £0c) <2o E iCnM iCnM iCnM iCnM iCnM iCnM iCnM CO spruce, a tree T3 _ ac, CD CD CD O &CD CD CD O CD Engelmann injury, CO c 8 8 cCoD 0CD> 9) 8 CCOD CCDD 8 £ I |3 = crown ES O’ N- N- CM of <> mo ~c CD CM CD CM co COM’ Douglas-fir, -Estimates m2 Qa- cUoJ 0$. = 1. h- co DF pine, Table oeacCarO- LzX(coCL0D CC3_CocILDoL uZ_ICcOQ_O) hC6.CcCt-DDOl LzIJCcCLDOD QCCCOO3.DL ORVkCCCoD.DD> CO-3C>CDCDO LzICc00LO)> OOLCCCODLL LzXCcoCLOD oCaD> TC03O) ’LodL=gePpole Figure 2.--Heavy exudate issuing from bole of dead lodgepole pine. vertical and horizontal) being exerted in the lower bole. The fermentation process by which the milky exudate is produced or its chemical makeup is unknown. The 2-year sequence of photographs taken of individual trees and stands provides a visual record of their present condition, including permanent damage, mortality, or signs of recovery. DISCUSSION There is little doubt that stands of lodgepole pine were highly vulnerable to winter injury, more than other coniferous species (Figure 3.). At this time, it is difficult to determine whether or not the trees that survived through 1990 will recover. We believe, however, that additional trees will die in 1991, particularly those with a low live/dead crown ratio (Table 1.) and those with meager live crowns. Many lodgepole pines in reproduction areas exhibited severe crown injury in 1989, but most experienced good recovery in 1990. It is believed that the younger, faster growing trees are considerably more resistant to permanent cold injur/ than their mature and overmature neighbors 6 A Followup Survey of Winter Injury In the Forests ofMontana, 1990