Kamloops Forest Region Drought Assessment Project
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KamloopsForest Region 2 1 Ministry ofForests Pacific EcologicalServices KAMLOOPS FOREST REGION Kamloops F 1999 - 2000 BACKGROUND Drought insect pestsisdiscussedwithmanagementimplications. interactions betweendroughtstressedtreesandsecondary on theforestsinKamloopsForestRegion.Inaddition, This reportsummarizessomeoftheeffects1998drought 1998 amongthedriestsummersonrecord. Canada alsoexperienceddryerthannormalconditions,ranking August was1.8degreesCelsiusabovenormal.Mostregionsin Canada. TheaveragetemperatureinCanadaforJunethrough The summerof1998wasthewarmestonrecordin Forrest Joy DROUGHT ASSESSMENT 12 Project AndLorraineMaclauchlan Assessment orest Region PROJECT Annual weather patterns have a All identified drought affected areas profound influence on forest were digitized in an ArcView format. The environments, affecting tree growth and number of hectares affected in each greatly influencing native insect district was determined and stratified by populations. Moisture stress, caused by biogeoclimatic zone and subzone. A low precipitation coupled with high daily detailed flight was made over selected temperatures, can cause reduced areas to map, photograph and stratify growth, defoliation, and even tree areas for ground survey. mortality. Many insects are “opportunists” and take advantage of Ground surveys were concentrated in stressed trees. Many insect pest the forest districts with the greatest outbreaks have been cited as having incidence of drought mortality (Table 1). started in drought-affected areas (Haack Eighteen young stands and 28 mature et al. 1989; Markalas 1991; and Dunn stands were surveyed in the Vernon, and Lorio 1993). Drought affected stand of 16 year old lodgepole pine in the Vernon Forest District, Aberdeen Plateau area. The 1999 Kamloops Regional aerial Salmon Arm, Kamloops, Clearwater and overview surveys delineated 10,035 Merritt Forest Districts. hectares of drought affected area (Maclauchlan 2000). The affected area represented mortality only, since other Table 1. Forest District and Mortality impacts of the drought were not visible No. of from the air. The mapped areas were Hectares of Stands starting points to focus our investigations Forest Drought Ground in 1999. The objectives of this project District Mortality Surveyed were to: Clearwater 230 2 ! determine the affected area within Kamloops 700 3 the stand; Salmon Arm 4030 21 ! assess the stand for incidence Vernon 4375 19 and impact of secondary or Penticton 600 0 other pests; and Merritt 50 1 ! determine the relative importance Lillooet 50 0 of drought and pests. Totals 10,035 46 CLIMATE Climate data were provided by months. In 1998 there was less rain in Environment Canada (Lahn 2000). July and August (22mm and 33.1mm, respectively) than the historic average. The summer of 1998 was the warmest and one of the driest in Canada on record. The average temperature in the Figure 3 Vernon and Salmon Arm areas was Days Without Precipitation 30.8º C, which was 4.27º C above 35 normal. In July and August there were 30 ) s 25 y a Figure 1 d 20 Vernon ( t o n 15 Salmon Arm Days Above 25 C u o C 10 30 5 25 0 ) s July August September y 20 a d ( Vernon Month (1998) t 15 n Salmon Arm u o 10 C 5 Other effects of this drought were 0 noticeable during the summer of 1998. July August September Numerous, severe forest fires occurred. Month (1998) In the Kamloops Forest Region 24,773.5 hectares were burned. The over 26 days above 25º C with the Kamloops Fire Center imposed a average temperature around 30º C. complete Forest closure in the Merritt September was slightly cooler but there Forest District from September 9th to were still greater than 12 days above 25 September 19th 1998. º C (Fig. 1,2). Figure 4 Figure 2 Comparison of 1998 Precipitation to Historical Mean Comparison of 1998 Temperature data to 50 Historical Mean ) 40 m m ( 30 e 35 t r July n u u t 30 20 o a Aug r ) m e 25 s July A p 10 e Sept e 20 m r Aug e g 0 T 15 e d e Sept ( 10 1998 Vernon Historical 1998 Salmon Historical g a Mean Arm Mean r 5 e v 0 Average 1998 Precipitation Data Compared to A 1998 Vernon Historical 1998 Salmon Historical Mean Recorded Precipitation Mean Arm Mean 1998 Temperature vs. Historical Mean Symptoms of drought stress became apparent in some areas by the fall of July through September saw over 24 1998. During the spring of 1999 many days per month with no precipitation trees began fading and extensive (Fig. 3). Comparison of the total mortality was observed in both young monthly precipitation in the summer of and old trees. 1998 to the historical mean (Fig. 4) shows a significant difference for all METHODS The data gathered from the 1999 Samples of insects pests were collected Kamloops Forest Region aerial overview for identification when field identification surveys were used to identify areas with was difficult. significant drought mortality (Appendix 1,2). Detailed aerial surveys were then In a subset of young stands, surveys of performed on the chosen areas to pest incidence (SPI) lines were further stratify and photograph affected established. This survey methodology areas. From aerial surveys and quantifies pest incidence in a stand. photographs, areas with significant Contiguous 100 meter plots are mortality were selected for ground randomly placed in the stand. The plot surveys (Appendix 3). width ranges from 0.5 to 5 meters wide depending on the density of the stand. Ground surveys involved a All trees and pests encountered are reconnaissance survey of the drought tallied and representative tree attribute affected area. Data were collected on data recorded (Maclauchlan and Merler stand characteristics (tree species 1990). composition, understory and ground cover composition), site characteristics The aerial photographs were mapped (slope, aspect, soil depth, and general onto 1:20,000 ORTHO map series. The site description), representative tree percent morality attributed to drought attribute data (tree species, height, dbh, was calculated from data recorded percent live crown, age and drought during ground surveys and from aerial effects) and forest health information. photo interpretation. Total polygon area Representative photographs were taken and ecosystem information was in each stand. Descriptive photographs obtained from Forest Inventory Files of all pests of interest were taken. (FIP) files. YOUNG STAND SURVEYS Eighteen young stands were surveyed in surveyed were in the MS biogeoclimatic total. Fourteen young stands were zone, six in the ICH and three in the IDF. surveyed in the Vernon Forest District in In total, six different biogeoclimatic the Aberdeen Plateau area and the subzones were surveyed (Table 2). Harris Creek area. Two young stands The total area ground surveyed was were surveyed in the Salmon Arm Forest 407.5 hectares. Of this the total affected District both in the Larch Hills area. One area was 195.7 hectares. Mortality young stand was surveyed in the ranged from 5 to 50 percent per stand, Kamloops Forest District near Spillman averaging 28.3 percent. Creek on the East side of Adams Lake and one in the Merritt Forest District near Many of the young stands surveyed Pothole Creek. All stands ranged in age were flat to rolling with areas of exposed from 5 to 17 years old except for the bedrock and shallow soils. Most of the Spillman Creek stand, that was drought occurred on rock outcroppings, approximately 22-30 years old. higher, exposed areas and areas with Lodgepole pine was the leading species well drained soils. In most cases the in most stands. Eight of the stands heavily drought affected areas had fewer Table 2. Young Stand Area, Percent Mortality and Ecosystem Data Area (ha) Average Species District No. Sites Total Affected Mortality(%) Ecosystem Affected Salmon Arm 2 72.5 41.5 25 ICH mw2 Lw, Fd Vernon 8 166.2 71.1 36.9 MS dm1 Pl Vernon 3 50.7 18.7 13.3 ICH mk1 Pl Vernon 2 62.6 15.3 22.5 IDF mw1 Pl, Fd Vernon 1 18.5 12.2 20 IDF xh1, MS dm1 Pl Kamloops 1 37 37 40 ICH mw3 Pl Merritt 1 Data Unavailable Pl Totals 18 407.5 195.7 26.3 stems per hectare than the unaffected area, indicating that these areas are poor growing sites and are likely difficult to regenerate. Many secondary insect pests were found colonizing drought affected trees. The most prevalent were twig beetles of the genera Pityophthorus and Pityogenes found in 66.6 percent of the stands surveyed. Hylurgops sp., were found in 50 percent of the stands surveyed and Pissodes schwarzi was found in 56 percent of the stands (Table 3). Aerial photograph of a young drought affected stand Vernon Forest District. Secondary pests found in fewer stands included Hylastes sp., Scolytus spp., Ips spp., Dendroctonus valens, Magdalis gentilis, Psuedohylesinus sp., and Pityokteines minutus. Most secondary insect attack occurred during the summer or fall of 1998. These opportunistic insects were attracted to the drought stressed trees. This secondary insect attack caused greater mortality than would have been experienced from the drought alone. The literature documents other cases where similar insect pest populations have significantly increased and have attacked not only drought stressed trees but healthy live trees as well (Furniss and Carolin 1977, Markalas 1992, Hack Drought mortality in a young stand, Vernon Forest District. and Schwartz 1997). It is not known what the populations of secondary pests we encountered will do in the summer of 2000, but continued extensive mortality is not expected. Drought mortality in a young stand. Table 3. Young Stand Pest Incidence Data Pests by Forest Health Agent No. of Surveyed Occurrence Sites With (%) * Common Name Latin Name Pest Bark Beetles Red turpentine beetle Dendroctonus valens 1 5.5 Twig beetles Pityophthorus and Pityogenes sp. 12 66.7 Hylastes species Hylastes sp. 4 22.2 Hylurgops species Hylurgops sp. 9 50.0 Ambrosia beetles Gnathotrichus and Trypodendron 14 77.8 Engraver beetles Scolytus sp.