WOODPECKER PREDATION ON BARK BEETLES IN ENGELMANN SPRUCE LOGS AS RELATED TO STAND DENSITY

1970 ◽  
Vol 102 (11) ◽  
pp. 1345-1354 ◽  
Author(s):  
Roland S. Shook ◽  
Paul H. Baldwin

Abstract Eighty Engelmann spruce logs (Picea engelmannii Parry), which were distributed in open (bulldozed to clearcut), semi-open (selectively cut), and dense (uncut) spruce forest, were infested with Dendroctonus obesus (Mann.) and Ips pilifrons Sw. and fed upon by northern three-toed and hairy woodpeckers. Sections of the infested boles were covered with screen to prevent woodpecker feeding and all logs were left in the field over one winter and through the following summer. By spring, the spruce beetle brood was reduced approximately 50% in all three forest areas. By fall, the spruce beetle brood suffered a 71, 83 and 52% reduction in the open, semi-open and dense forest, respectively. Spruce beetles appeared to be in greatest numbers in the semi-open forest, resulting in the greatest woodpecker predation there. Woodpeckers did not feed in the open meadows. Estimates in the spring, before the Ips emerged from the logs, showed that woodpeckers reduced the Ips brood by 76 and 11% in the open and semi-open forest, respectively. Ips were not found in dense forest or in meadows.

2020 ◽  
Vol 55 (3) ◽  
pp. 301-309
Author(s):  
Christopher J. Fettig ◽  
A. Steven Munson ◽  
Donald M. Grosman ◽  
Darren C. Blackford

Abstract Bark beetles are important disturbance agents in coniferous forests, and spruce beetle, Dendroctonus rufipennis (Kirby) (Coleoptera: Curculionidae), is one of the more notable species causing landscape-level tree mortality in western North America. We evaluated the efficacy of bole injections of emamectin benzoate (TREE-äge®; Arborjet Inc., Woburn, MA) alone and combined with propiconazole (Alamo®; Syngenta Crop Protection Inc., Wilmington, DE) for protecting Engelmann spruce, Picea engelmannii Parry ex Engelmann (Pinales: Pinaceae), from mortality attributed to colonization by D. rufipennis. Two injection periods in 2013 (the spring and fall of the year prior to trees first being challenged by D. rufipennis in 2014) and distributions of injection points (7.6- and 15.2-cm spacings) were evaluated. Tree mortality was monitored over a 3-yr period (2014–2017). Emamectin benzoate injected in spring at a narrow spacing (7.6 cm) was the only effective treatment. Two (but not three) field seasons of protection can be expected with a single injection of this treatment. We discuss the implications of these and other results regarding the use of emamectin benzoate and propiconazole for protecting western conifers from mortality attributed to bark beetles, and provide suggestions for future research. A table summarizing the appropriate timing of treatments in different bark beetle/host systems is provided.


2019 ◽  
Vol 112 (5) ◽  
pp. 2253-2261 ◽  
Author(s):  
E Matthew Hansen ◽  
A Steven Munson ◽  
David Wakarchuk ◽  
Darren C Blackford ◽  
Andrew D Graves ◽  
...  

AbstractWe tested 3-methyl-2-cyclohexen-1-one (MCH) and novel semiochemicals as potential spruce beetle (Dendroctonus rufipennis Kirby) (Coleoptera: Curculionidae, Scolytinae) repellents over multiple years in Utah and Colorado trapping bioassays. MCH is a known spruce beetle repellent and our testing revealed Acer kairomone blend (AKB) and isophorone plus sulcatone as repellents. We subsequently tested these semiochemicals for area and single tree protection to prevent spruce beetle attacks at locations in Utah, Colorado, Wyoming, New Mexico, and Alaska. Individual tree protection trials found MCH–AKB provided significant protection against spruce beetle attacks in the southern Rocky Mountains but not in Alaska. Adding sulcatone or doubling MCH–AKB pouches did not further enhance protection. A degree of protection was extended to spruce at least 10 m distant from the repellents, including in Alaska. Tree diameter was not a significant covariate among treated trees but was positively correlated with the probability of infestation for surrounding spruce. In area protection trials, spruce in control plots were 2.4 times more likely to be in a higher severity attack class compared with spruce in plots treated with MCH–AKB pouches deployed at 30 sets per hectare. Tree diameter had a significant, positive relationship to the probability of infestation. We found MCH–AKB to offer a high degree of protection against beetle attack in Engelmann spruce (Picea engelmannii Parry ex Engelm.) (Pinales: Pinaceae) (Picea engelmannii Parry ex Engelm.) (Pinales: Pinaceae), especially for single tree protection (66% of control trees were strip- or mass-attacked compared with 6% of repellent-treated trees). AKB requires registration and labeling, however, before this economical and environmentally benign semiochemical can be used operationally.


2020 ◽  
Vol 152 (6) ◽  
pp. 790-796
Author(s):  
Thomas Seth Davis

AbstractEngelmann spruce, Picea engelmannii Parry ex Engelm. (Pinaceae), in the southern Rocky Mountains is composed of two distinct phloem monoterpene chemotypes that differ in relative abundances of multiple monoterpenes, particularly α-pinene and Δ3-carene (hereafter, the “α-pinene chemotype” and the “Δ3-carene chemotype”). Here, relative toxicity of these chemotypes is tested on spruce beetle (Dendroctonus rufipennis Kirby) (Coleoptera: Scolytinae), a phloeophagous herbivore that colonises trees of both types. Synthetic monoterpene blends representing each chemotype were tested across a range of concentrations (0, 10, 50, 100, 200, and 500 µg/L) in the lab, and probability of survival of adult beetles exposed to each blend was modelled using a logit function. Logit curves were solved to determine LC25, LC50, and LC75 of each monoterpene blend. On average, probability of beetle survival was lower when exposed to the Δ3-carene chemotype than when exposed to the α-pinene chemotype. However, both chemotypes were completely lethal to beetles at concentrations exceeding 100 µg/L. Adult body mass did not affect survival probability. It is concluded that spruce phloem chemotypes may differ in their toxicity to spruce beetles, with potential consequences for patterns of host-tree colonisation by spruce beetle.


2008 ◽  
Vol 84 (3) ◽  
pp. 401-409 ◽  
Author(s):  
Alan Vyse ◽  
Christine Ferguson ◽  
David J Huggard

We used transect surveys at a large-scale experimental site at Sicamous Creek, B.C. to measure the effects of five treatments on wind and snow damage in an old subalpine fir – Engelmann spruce forest: 10-ha clearcuts, arrays of 1-ha patch cuts, arrays of 0.1-ha patch cuts, individual-tree selection cuts and uncut controls. We also examined edge effects and conditions predisposing trees to damage. Transects were surveyed in 1997, 1999 and 2003 (2.7, 4.7 and 8.7 years postharvest). The increase in wind damage in the four harvested treatments compared to the uncut controls observed after 2.7 years was no longer evident following a snow damage event in the winter of 1998–1999, which was most severe in the uncut controls and leave strips. The damage recorded from this event was predominantly stem snapping rather than uprooting. Subsequent damage was low in all treatments, returning to the level first recorded in the uncut controls. Overall, after 8.7 years, the treatment differences were not statistically significant but the lowest average rates of damage were observed in the 0.1-ha patch cut arrays. The highest damage rates overall were observed within 10 m of the N and E edges of the 10-ha clearcuts. Damage rates in Engelmann spruce continued to be lower than rates for subalpine fir. Stem snapping, caused by some combination of snow loading and wind, is an underreported but widespread disturbance in these stands. Key words: ESSF forest, wind damage, snow damage, snapping, uprooting, subalpine fir (Abies lasiocarpa [Hook] Nutt.), Engelmann spruce (Picea engelmannii Parry ex Engelm.), silvicultural systems, Sicamous Creek


2020 ◽  
Vol 50 (5) ◽  
pp. 465-472
Author(s):  
Jane E. Stewart ◽  
Franklin L. Harris ◽  
Kristen Otto ◽  
Thomas Seth Davis

Symbiotic fungi associated with tree-killing bark beetles can alter host-tree physiology with consequences for tree survival, and symbiont genetic variation and environmental variability may impact these interactions. Here, we test whether multiple genetically distinct isolates of a symbiotic fungus (Leptographium abietinum (Peck) M.J. Wingf.) associated with North American spruce beetle (Dendroctonus rufipennis (Kirby, 1837)) vary in their ability to manifest defensive responses consistent with disease symptoms in seedlings of Engelmann spruce (Picea engelmannii Parry ex Engelm.), a primary host-tree species for the beetle–fungus complex in North America. Our experiments incorporate variation in both host-tree water availability and host defenses (phloem monoterpene concentration). Three central findings emerged: (i) isolates varied considerably in their effects on host trees — inoculation with L. abietinum isolates from Colorado caused significantly larger phloem lesions than isolates from Wyoming, though all isolates caused phloem oxidation; (ii) neither water availability nor spruce phloem monoterpene concentrations impacted lesion formation; and (iii) both inoculation with L. abietinum and water deficit inhibited the formation of callus tissue at wound sites. We conclude that L. abietinum isolates vary in their virulence and that inoculation is not lethal but may benefit beetles by altering tree defensive responses.


2006 ◽  
Vol 36 (10) ◽  
pp. 2574-2584 ◽  
Author(s):  
E Matthew Hansen ◽  
Barbara J Bentz ◽  
A Steven Munson ◽  
James C Vandygriff ◽  
David L Turner

Although funnel traps are routinely used to manage bark beetles, little is known regarding the relationship between trap captures and tree mortality near the trap. We conducted a 4 year study in Utah to examine the correlation between funnel-trap captures of spruce beetle (Dendroctonus rufipennis Kirby) and mortality of Engelmann spruce (Picea engelmannii Parry ex Engelm.) within a 10 ha block of the trap. Using recursive partitioning tree analyses, rules were developed for predicting spruce mortality and associated levels of beetle population phase (endemic or epidemic), in the current year and subsequent year, for a given level of trap captures. Although model predictions of infested-stem counts had large variances, our results suggest that funnel-trap captures can be reliably used to estimate relative levels of tree mortality, expressed as spruce beetle population phase. Classification-tree analyses indicate that captures of ~842 spruce beetles during a season (late May to mid-August) from a single funnel trap represent a threshold between endemic (<2 mass-attacked stems/ha) and epidemic conditions (≥2 mass-attacked stems/ha) for either the current or the subsequent year relative to deployment of the funnel trap. Likewise, a lack of infested hosts within 10 m of a funnel trap, also known as spillover, was associated with endemic conditions, whereas trees attacked near the trap correlated with epidemic conditions.


2000 ◽  
Vol 30 (1) ◽  
pp. 50-58 ◽  
Author(s):  
Matthew E Greenwood ◽  
John H Borden

Co-baiting to contain and concentrate the spruce beetle, Dendroctonus rufipennis (Kirby), and the western balsam bark beetle, Dryocoetes confusus Swaine, was investigated at four locations in British Columbia. Two 9-ha areas were established at each location; one was baited and the other left as a control. Single "interior firs," Abies bifolia A. Murray × Abies lasiocarpa (Hook.) Nutt., or groups of two or three trees, were baited with (±)-exo-brevicomin released at 1.0 mg/24 h. "Interior spruces," Picea engelmannii Engelm. ex Parry × Picea glauca (Moench) Voss, were baited with frontalin released at 0.1, 0.6, or 2.5 mg/24 h, or at 0.6 mg/24 h with alpha-pinene, ethanol, or ethyl crotonate. Another experiment investigated possible interspecific interference between D. confusus and D. rufipennis baits. Ratios of currently attacked "green" trees to previously attacked "red" trees for both insects were significantly higher in baited than in control areas, indicating that populations were contained. Baiting, however, did not attract either insect from a zone surrounding each baited area. There was a significant increase in D. confusus attack when two trees instead of one were baited per centre, no increase in D. rufipennis attack when frontalin was released alone or with the potential adjuvants, no effect of frontalin release rates on the percentage of trees attacked by D. rufipennis, and no indication of cross-repellency between baits.


2004 ◽  
Vol 59 (9-10) ◽  
pp. 641-648 ◽  
Author(s):  
Marek Mardarowicz ◽  
Dorota Wianowska ◽  
Andrzej L. Dawidowicz ◽  
Ryszard Sawicki

Abstract Terpenes emitted by conifer trees are generally determined by analysing plant extracts or essential oils, prepared from foliage and cones using steam distillation. The application of these procedures limits experiments to cut plant materials. Recently headspace techniques have been adopted to examine terpene emission by living plants. This paper deals with the application of solid-phase micro-extraction (SPME) for the analysis of terpenes emitted by conifers foliage of Engelmann spruce (Picea engelmannii), including its seedlings. The compositions of SPME extracts obtained for destroyed and non-destroyed old and juvenile spruce needles were compared with the compositions of essential oils and pressurised liquid extraction (PLE) extracts corresponding to the same plant materials. No substantial differences have been found in the qualitative terpene composition estimated by analysing essential oil and PLE and SPME extracts from non-destroyed old and juvenile foliage. The disintegration of spruce needles results in the formation of a significant amount of myrcene in the case of the old conifer foliage and non-terpenoic compounds in the case of juvenile conifer foliage. This phenomenon can be attributed to enzymatic reactions occurring in the destroyed plant cells.


1982 ◽  
Vol 60 (12) ◽  
pp. 2753-2761 ◽  
Author(s):  
Alan K. Knapp ◽  
William K. Smith

Although seedlings of Abies lasiocarpa are generally more abundant than those of Picea engelmannii in the understory of mature spruce–fir forests throughout the central and northern Rocky Mountains, little information exists concerning environmental or plant factors that may influence the establishment of these two conifers. Field measurements in the Medicine Bow Mountains of southeast Wyoming showed that seedlings of A. lasiocarpa had greater photosynthetic rates at low understory light levels and required lower levels of incident radiation for saturation of photosynthesis compared with those of P. engelmannii. However, both conifers occurred in understory locations where total daily solar radiation was equally low (<2 MJ∙m−2∙day−1) and thus, a lack of light did not appear to be responsible for the low number of P. engelmannii seedlings in the understory. In contrast, seedlings of P. engelmannii were substantially more abundant at locations with thinner litter layers compared with those of A. lasiocarpa. Also, laboratory studies showed that the smaller seeds of P. engelmannii germinated more rapidly and at lower temperatures than seeds of A. lasiocarpa although growth of tap roots on A. lasiocarpa seedlings was greater initially ([Formula: see text] longer in 2-week-old seedlings) as well as for 10-week-old seedlings (50% longer). The deeper penetrating tap root of A. lasiocarpa seedlings may enable this conifer to establish more abundantly on thick, rapidly drying litter layers that are characteristic of mature spruce–fir forests. In contrast, establishment of P. engelmannii seedlings may be limited to microsites without a thick litter layer such as disturbed areas or decomposing wood, where surface drying may occur more gradually throughout the summer. These results are discussed in terms of the potential effects of seedling establishment on the observed patterns in climax vegetation of central and northern Rocky Mountain subalpine forests.


2017 ◽  
Vol 40 (1) ◽  
pp. 1-8
Author(s):  
Bhawna Adhikari ◽  
◽  
Bhawana Kapkoti ◽  
Neelu Lodhiyal ◽  
L.S. Lodhiyal ◽  
...  

Present study was carried out to assess the structure and regeneration of Sal forests in Shiwalik region of Kumaun Himalaya. Vegetation analysis and tree canopy density was determined by using quadrat and densitometer, respectively. Density of seedlings, saplings and trees was 490-14067, 37-1233, and 273-863 ind.ha-1 respectively. The basal area was 0.12-5.44 m2 ha-1 reported for saplings and 25.4-77.6 m2 ha-1 for trees. Regeneration of Sal was found good in Sal mixed dense forest followed by Sal open forest and Sal dense forest, respectively. Regeneration of Sal was assisted by the presence of associated tree species as well as the sufficient sunlight availability on ground due to adequate opening of canopy trees in Sal forest. Thus it is concluded that the density of tree canopy, sunlight availability and also associated tree species impacted the regeneration of Sal in the region.


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