Advance regeneration and trajectories of stand development following the mountain pine beetle outbreak in boreal forests of British Columbia

2015 ◽  
Vol 45 (10) ◽  
pp. 1327-1337 ◽  
Author(s):  
Elizabeth M. Campbell ◽  
Joseph A. Antos

A mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreak has recently spread into boreal forests, with unknown consequences for this ecosystem. We intensively sampled 12 stands affected by the current outbreak in northern British Columbia to determine the potential of western boreal forests to recover from this novel disturbance. We sampled the species composition, size structure, and spatial distribution (using 5 m × 5 m subplots, 40 per stand) of live and dead trees and used a variety of analyses, including ordinations, to assess potential developmental trajectories of stands. Advance regeneration (stems < 10 m tall) varied greatly in abundance among stands (50–18 280 stems·ha−1). However, most subplots contained at least one individual; only three stands had many empty subplots. We conclude that most stands have enough advance regeneration and residual canopy trees to form a nearly continuous new canopy. Ordinations indicate that species composition will shift substantially and become more divergent among stands. Species of high economic value will remain common, though, and active management will not be necessary in most stands to maintain productive forests. However, this novel disturbance will have very different effects on these forests than the typical fire-disturbance regime and is likely to deflect these forests into new successional trajectories.

2008 ◽  
Vol 38 (11) ◽  
pp. 2826-2836 ◽  
Author(s):  
Gordon D. Nigh ◽  
Joseph A. Antos ◽  
Roberta Parish

Insect outbreaks, such as the current mountain pine beetle ( Dendroctonus ponderosae Hopkins) outbreak in lodgepole pine ( Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) forests in British Columbia, are major disturbances in many forests. After an insect outbreak, the advance regeneration typically forms a new canopy, which may be adequate for timber objectives in some stands. Our purpose was to quantify and then model the abundance and spatial distribution of advance regeneration (trees <10.0 m tall). We sampled understory and overstory trees in 28 lodgepole pine stands in south-central British Columbia at two spatial scales: 0.1 ha plots and 25 m2 subplots. We developed models predicting advance regeneration abundance and spatial distribution. Density of advance regeneration averaged 2689 trees/ha (range 120 to 23 000 trees/ha), most of which were <1 m tall. Although advance regeneration was clumped, 75% of the subplots contained at least one individual. Models indicated negative relationships of advance regeneration abundance to overstory basal area and density. Over half the stands had enough advance regeneration to form new stands of adequate density, indicating that use of advance regeneration is a viable option in this mountain pine beetle outbreak and probably other insect disturbances.


Forests ◽  
2018 ◽  
Vol 9 (9) ◽  
pp. 536 ◽  
Author(s):  
Kristen Pelz ◽  
Charles Rhoades ◽  
Robert Hubbard ◽  
Frederick Smith

The severity of lodgepole pine mortality from mountain pine beetle outbreaks varies with host tree diameter, density, and other structural characteristics, influencing subcanopy conditions and tree regeneration. We measured density and leader growth of shade-intolerant lodgepole pine, shade-tolerant Engelmann spruce, and very shade-tolerant subalpine fir regeneration beneath stands that experienced moderate and high overstory lodgepole pine mortality (average 40% and 85% of total basal area) a decade earlier. Lodgepole comprised >90% of the overstory basal area and mature spruce and fir were present in both mortality levels, though live basal area and disturbance history differed. Post-beetle outbreak recruitment was high in both mortality levels, but there were more lodgepole in high than moderate mortality plots (1140 stems ha−1 vs. 60 stems ha−1) and more subalpine fir in moderate than high mortality plots (4690 stems ha−1 vs. 2870 stems ha−1). Pine advance regeneration, established prior to outbreak, was more dense in high mortality than moderate mortality sites (930 stems ha−1 vs. 310 stems ha−1), but the trend was generally the opposite for the other conifers. Lodgepole recruitment increased and subalpine fir decreased with greater forest floor light availability. All species grew faster in high mortality areas than their counterparts in moderate mortality areas. However, in high mortality areas pine grew faster than the more shade tolerant species, and in moderate mortality areas spruce and fir grew faster than pine. These species-specific responses to the degree of overstory mortality will influence future stand composition and rate of forest recovery after mountain pine beetle outbreaks.


1987 ◽  
Vol 65 (1) ◽  
pp. 95-102 ◽  
Author(s):  
H. S. Whitney ◽  
R. J. Bandoni ◽  
F. Oberwinkler

A new basidiomycete, Entomocorticium dendroctoni Whitn., Band. & Oberw., gen. et sp. nov., is described and illustrated. This cryptic fungus intermingles with blue stain fungi and produces abundant essentially sessile basidiospores in the galleries and pupal chambers of the mountain pine bark beetle (Dendroctonus ponderosae Hopkins Coleoptera: Scolytidae) in lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.). The insect apparently disseminates the fungus. Experimentally, young partially insectary reared adult beetles fed E. dendroctoni produced 19% more eggs than beetles fed the blue stain fungi.


1989 ◽  
Vol 19 (1) ◽  
pp. 65-68 ◽  
Author(s):  
B. S. Lindgren ◽  
J. H. Borden ◽  
G. H. Cushon ◽  
L. J. Chong ◽  
C. J. Higgins

The effect of the aggregation-inhibiting pheromone verbenone on mountain pine beetle attacks in lodgepole pine stands was assessed by affixing verbenone release devices on trees on a 10 × 10 m grid. In one experiment, aggregation to trees baited with an attractive combination of trans-verbenol, exo-brevicomin, and myrcene was reduced in verbenone-treated blocks compared with control blocks (attractive baits only). The mean number of trees with mass attacks (≥31.3 attacks/m2), mean percentage of available trees mass attacked, and mean total number of trees infested were reduced by 74.3, 66.7, and 58.5%, respectively. The ratio of 1987 attacks to 1986 attacks was reduced from 14.0 to 2.6. In a second experiment, using no attractive baits, verbenone caused similar but nonsignificant reductions. The mean number of trees with mass attacks, mean percentage of available trees mass attacked, and mean total number of trees infested were reduced by 75.2, 53.5, and 62.1%, respectively. The 1987 to 1986 attack ratio was reduced from 13.2 in control blocks to 0.2 in the verbenone-treated blocks, and the percentage of trees that were infested but not mass attacked was significantly increased, from 45.7% in the control blocks to 63.2% in the verbenone-treated blocks. We conclude that verbenone shows promise as a management tool for controlling the mountain pine beetle.


2000 ◽  
Vol 30 (7) ◽  
pp. 1051-1059 ◽  
Author(s):  
Elizabeth M Campbell ◽  
Joseph A Antos

A major decline in the abundance of whitebark pine (Pinus albicaulis Engelm.) has recently occurred in the United States, primarily as a result of white pine blister rust (Cronartium ribicola J.C. Fisch. ex Raben.). However, no information on the status of whitebark pine in British Columbia, Canada, was available. We sampled 54 subalpine stands in British Columbia, examining all whitebark pine trees within plots for evidence of blister rust and mountain pine beetle (Dendroctonus ponderosae Hopk.) damage. About 21% of all whitebark pine stems were dead, and blister rust was the most important agent of mortality. Of all living trees sampled, 27% had obvious blister rust infection (cankers), but actual incidence was suspected of being as high as 44% (using all evidence of blister rust). Blister rust incidence and whitebark pine mortality were significantly related to differences in stand structure and the presence of Ribes spp., but relationships with local climate and site variables were absent or weak. The lack of strong relationships with climate suggests favourable conditions for the spread of the disease throughout most of British Columbia. Very little evidence of mountain pine beetle was found. Overall, the prospects for whitebark pine in British Columbia do not appear good; a large reduction in population levels seems imminent.


1983 ◽  
Vol 13 (2) ◽  
pp. 325-333 ◽  
Author(s):  
J. H. Borden ◽  
J. E. Conn ◽  
L. M. Friskie ◽  
B. E. Scott ◽  
L. J. Chong ◽  
...  

Lodgepole pines, Pinuscontorta var. latifolia Engelm., in three interior British Columbia locations were baited with six monoterpenes alone or combined, and various combinations of the beetle-produced volatiles trans-verbenol, exo-brevicomin, and 3-caren-10-ol. Trees baited with trans-verbenol, exo brevicomin, and the monoterpene 3-carene sustained higher attack densities by the mountain pine beetle, Dendroctonusponderosae Hopkins, and were surrounded by more attacked trees than trees baited with trans-verbenol and 3-carene or unbaited controls. Myrcene was apparently the best of six monoterpenes as a synergist for trans-verbenol. 3-Caren-10-ol appeared to have some activity in an early test but did not prove to be an attractive pheromone in extensive studies. In a 17-ha portion of an infestation, treatment of 99 trees with 3-carene and trans-verbenol apparently caused a higher attack rate, resulting in 56.4% of the available green trees being attacked, as opposed to 22.3% of the available trees in the 14-ha unbaited area. These data as well as the high attack rates associated with trees which also had an exo-brevicomin bait suggest that semiochemicals could be used to contain D. ponderosae infestations and to attract beetles to lethal trap trees.


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