Editing Spruce (section)

== Ecology ==

=== Diseases ===
[[File:Fichtenstamm entrindet.jpg|thumb|Manually [[Debarking (lumber)|decorticated]] [[Tree#Trunk|trunk]] of a spruce as protection against [[bark beetle]]s]]
[[File:Древесина ели.jpg|thumb|Structure of spruce tree cells]]

==== ''Sirococcus'' blight (Deuteromycotina, Coelomtcetes) ====
The closely related species ''Sirococcus conigenus'' and ''Sirococcus piceicola'' cause shoot blight and seedling mortality of [[Pinophyta|conifers]] in North America, Europe, and North Africa.<ref>{{cite journal |last1=Rossman |first1=AY |last2=Castlebury |first2=LA |last3=Farr |first3=DF |last4=Stanosz |first4=GR |date=2008 |title=''Sirococcus conigenus'', ''Sirococcus piceicola'' sp. nov. and ''Sirococcus tsugae'' sp. nov. on conifers: anamorphic fungi in the Gnomoniaceae, Diaporthales |journal=Forest Pathology |volume=38 |pages=47–60 |doi=10.1111/j.1439-0329.2007.00529.x|doi-access=free }}</ref> Twig blight damage to seedlings of white and [[Picea rubens|red spruces]] in a nursery near Asheville, North Carolina, was reported by Graves (1914).<ref name="graves">{{cite journal |author=Graves, A.H. |year=1914 |title=Notes on diseases of trees in the southern Appalachians |journal=Phytopath |volume=4 |pages=63–72}}</ref> Hosts include [[White spruce|white]], [[Picea mariana|black]], [[Picea engelmannii|Engelmann]], [[Picea abies|Norway]], and [[Picea rubens|red spruces]], although they are not the plants most commonly damaged. ''Sirococcus'' blight of spruces in nurseries show up randomly in [[seedling]]s to which the fungus was transmitted in infested seed. First-year seedlings are often killed, and larger plants may become too deformed for planting. Outbreaks involving < 30% of spruce seedlings in seedbeds have been traced to seed lots in which only 0.1% to 3% of seeds were infested. Seed infestation has in turn been traced to the colonization of spruce cones by ''S. conigenus'' in forests of the western interior. Infection develops readily if conidia are deposited on succulent plant parts that remain wet for at least 24 hours at 10&nbsp;°C to 25&nbsp;°C. Longer periods of wetness favour increasingly severe disease. Twig tips killed during growth the previous year show a characteristic crook.

==== ''Rhizosphaera kalkhoffi'' needle cast ====
''Rhizosphaera'' infects white spruce, [[blue spruce]] (''Picea pungens''), and Norway spruces throughout Ontario, causing severe defoliation and sometimes killing small, stressed trees. White spruce is intermediately susceptible. Dead needles show rows of black fruiting bodies. Infection usually begins on lower branches. On white spruce, infected needles are usually retained on the tree into the following summer. The fungicide Chlorthalonil is registered for controlling this needle cast (Davis 1997).<ref name="davis">Davis, C. (24 September 1997) "Tree talk". ''The Sault Star''. Marie, Ontario. p. B2.</ref>

==== ''Valsa kunzei'' branch and stem canker ====
A branch and stem canker associated with the [[fungus]] ''Valsa kunzei'' Fr. var. ''picea'' was reported on white and Norway spruces in Ontario (Jorgensen and Cafley 1961)<ref name="jorg">{{cite journal |author=Jorgensen, E. and Cafley, J.D. |year=1961 |title=Branch and stem cankers of white and Norway spruces in Ontario |journal=For. Chron. |volume=37 |issue=4 |pages=394–400 |doi=10.5558/tfc37394-4|doi-access=free }}</ref> and Quebec (Ouellette and Bard 1962).<ref name="ouel">{{cite journal |author=Ouellette, G.B.; Bard, G. |year=1962 |title=Observations on a canker and resinosis in white and Norway spruce |journal=Can. Dep. For., for. Ent. Path. Branch, Ottawa ON, Bi-mo. Progr. Rep. |volume=18 |issue=2 |pages=2}}</ref> In Ontario, only trees of low vigour were affected, but in Quebec vigorous trees were also infected.

=== Predators ===
[[File:Spruce in the park of Peterhof.jpg|thumb|Spruce in the park of Peterhof]]
Small [[mammal]]s ingest [[Pinophyta|conifer]] seeds, and also consume [[seedling]]s. Cage feeding of deer mice (''Peromyscus maniculatus'') and red-backed vole (''Myodes gapperi'') showed a daily maximum seed consumption of 2000 white spruce seeds and of 1000 seeds of [[Pinus contorta|lodgepole pine]], with the two species of mice consuming equal amounts of seed, but showing a preference for the pine over the spruce (Wagg 1963).<ref name="wagg1">{{cite journal |author=Wagg, J.W.B. |year=1963 |title=Notes on food habits of small mammals of the white spruce forest |journal=For. Chron. |volume=39 |issue=4 |pages=436–445 |doi=10.5558/tfc39436-4 |doi-access=free}}</ref> The short-tailed meadow vole (''Microtus pennsylvanicus'' Ord) voraciously ate all available white spruce and lodgepole pine seedlings, pulling them out of the ground and holding them between their front feet until the whole seedling had been consumed. Wagg (1963)<ref name="wagg1" /> attributed damage observed to the bark and cambium at ground level of small white spruce seedlings over several seasons to meadow voles.

Once shed, seeds contribute to the diet of small mammals, e.g., [[Peromyscus|deer mice]], [[Clethrionomys|red-backed vole]]s, [[Montane vole|mountain voles]] (''Microtus montanus''), and [[chipmunk]]s (''Eutamias minimus''). The magnitude of the loss is difficult to determine, and studies with and without seed protection have yielded conflicting results. In western Montana, for example, spruce seedling success was little better on protected than on unprotected seed spots (Schopmeyer and Helmers 1947),<ref name="schop">Schopmeyer, C.S.; Helmers, A.E. 1947. Seeding as a means of [[reforestation]] in the northern Rocky Mountain Region. USDA For. Serv., Washington DC, Circular 772. 30 p.</ref> but in British Columbia spruce regeneration depended on protection from rodents (Smith 1955).<ref name="smith">Smith, J.H.G. 1955 [1956 acc to E3999 bib]. Some factors affecting reproduction of Engelmann spruce and alpine fir. British Columbia Dep. Lands For., For. Serv., Victoria BC, Tech. Publ. 43 p. [Coates et al. 1994, Nienstaedt and Teich 1972]</ref>

An important albeit indirect biotic constraint on spruce establishment is the depredation of seed by [[squirrel]]s. As much as 90% of a cone crop has been harvested by red squirrels (Zasada et al. 1978).<ref name="zasada">Zasada, J.C.; Foote, M.J.; Deneke, F.J.; Parkerson, R.H. 1978. Case history of an excellent white spruce cone and seed crop in interior Alaska: cone and seed production, germination and seedling survival. USDA, For. Serv., Pacific NW For. Range Exp. Sta., Portland OR, Gen. Tech. Rep. PNW-65. 53 p.</ref> Deer mice, voles, chipmunks, and shrews can consume large quantities of seed; one mouse can eat 2000 seeds per night.<ref name="rad2">{{cite journal |last1=Radvanyi |first1=A |year=1970 |title=Small mammals and regeneration of white spruce forests in western Alberta |journal=Ecology |volume=51 |issue=6 |pages=1102–1105 |doi=10.2307/1933641 |jstor=1933641|bibcode=1970Ecol...51.1102R }}</ref> Repeated applications of half a million seeds/ha failed to produce the 750 trees/ha sought by Northwest Pulp and Power, Ltd., near Hinton, Alberta (Radvanyi 1972),<ref name="rad3">Radvanyi, A. 1972. Small mammals and regeneration of white spruce in western Alberta. p. 21–23 ''in'' McMinn, R.G. (Ed.). White Spruce: Ecology of a Northern Resource. Can. Dep. Environ., Can. For. Serv., Edmonton AB, Inf. Rep. NOR-X-40.</ref> but no doubt left a lot of well-fed small mammals. Foraging by squirrels for winter buds (Rowe 1952)<ref name="rowe1">Rowe, J.S. 1952. Squirrel damage to white spruce. Can. Dep. Resour. Devel., For. Branch, For. Res. Div., Ottawa ON, Silv. Leafl. 61. 2 p.</ref> has not been reported in relation to young plantations, but Wagg (1963)<ref name="wagg1" /> noted that at Hinton AB, [[American red squirrel|red squirrel]]s were observed cutting the lateral and terminal twigs and feeding on the vegetative and flower buds of white spruce.

[[American red squirrel|Red squirrel]]s in Alaska have harvested as much as 90% of a cone crop (Zasada et al. 1978);<ref name="zasada" /> their ''modus operandi'' is to cut off great numbers of cones with great expedition early in the fall, and then "spend the rest of the fall shelling out the seeds". In Manitoba, Rowe (1952)<ref name="rowe1" /> ascribed widespread severing of branch tips 5&nbsp;cm to 10&nbsp;cm long on white spruce ranging "from sapling to veteran size" to squirrels foraging for winter buds, cone failure having excluded the more usual food source. The damage has not been reported in relation to small trees, outplants or otherwise.

[[Porcupine]]s (''Erethizon dorsatum'' L.) may damage spruce (Nienstaedt 1957),<ref name="nien">Nienstaedt, H. 1957. Silvical characteristics of white spruce (''Picea glauca''). USDA, For. Serv., Lake States For. Exp. Sta., St. Paul MN, Pap. 55. 24 p.</ref> but prefer red pine.<ref name="mcleod">{{cite report |url=https://cfs.nrcan.gc.ca/publications?id=30504 |title=Plantations of the Acadia Forest Experiment Station |last=McLeod |first=J.W. |date=1956 |publisher=Can. Dep. Northern Affairs National Resour., For. Branch, For. Res. Div. |id=Tech. Note 31}}</ref> Bark-stripping of white spruce by black bear (''Euarctos americanus perniger'') is locally important in Alaska (Lutz 1951),<ref name="lutz">{{cite journal |author=Lutz, H.J. |year=1951 |title=Damage to trees by black bears in Alaska |journal=J. For. |volume=49 |pages=522–523}}</ref> but the bark of white spruce is not attacked by field mice (''Microtus pennsylvanicus'' Ord),<ref name="little">{{cite journal |author=Littlefield |first1=E.W. |last2=Schoomaker |first2=W.J. |last3=Cook |first3=D.B. |year=1946 |title=Field mouse damage to coniferous plantations |journal=J. For. |volume=44 |pages=745–749}}</ref> even in years of heavy infestation.

=== Pests ===
The eastern spruce budworm (''[[Choristoneura fumiferana]]'') is a major pest of spruce trees in forests throughout Canada and the eastern United States.<ref name="Powell">{{Cite book |url=https://books.google.com/books?id=YH7WzKFzX0MC&pg=PP1 |title=Biosystematic Studies of Conifer-Feeding Choristoneura (Lepidoptera Tortricidae) in the Western United States |date=1995 |publisher=University of California Press |isbn=9780520097964 |editor-last=Powell |editor-first=Jerry A.}}</ref> Two of the main host plants are [[Picea mariana|black spruce]] and [[white spruce]].<ref name="bal2">Balch, R.E.; Webb, F.E.; Morris, R.F. (1954). [https://cfs.nrcan.gc.ca/publications?id=8263 Results of spraying against spruce budworm in New Brunswick]. Can. Dep. Agric., For. Biol. Div., Ottawa ON, Bi-mo. Progr. Rep. 10(1).</ref> Population levels oscillate, sometimes reaching extreme outbreak levels that can cause extreme defoliation of and damage to spruce trees. To reduce destruction, there are multiple methods of control in place, including pesticides.<ref name="Pheromone">{{Cite book |last1=Allison |first1=Jeremy D. |url=https://books.google.com/books?id=1GjgDAAAQBAJ |title=Pheromone Communication in Moths: Evolution, Behavior, and Application |last2=Carde |first2=Ring T. |date=2016 |publisher=Univ of California Press |isbn=9780520964433 |pages=265–271}}</ref>

Horntails, or Wood Wasps, use this tree for egg laying and the larvae will live in the outer inch of the tree under the bark.

Spruce beetles (''[[Dendroctonus rufipennis]]'') have destroyed swathes of spruce forest in western North America from Alaska to Wyoming.