Picea rubens Sarg. Red Spruce Pinaceae Pine family Barton M. Blum Red spruce (Picea rubens), also known as yellow balsam, is one of the more important conifers in the spruce, West Virginia spruce, eastern spruce, and he- northeastern United States and adjacent Canada. It The author is Research Forester, Northeastern Forest Experiment Station, Radnor, PA. 250 Picea rubens is a medium-size tree that may grow to be more than spruce is found predominantly on shallow till soils 400 years old. The wood of red spruce is light in color that average about 46 cm (18 in) to a compact layer. and weight, straight grained, and resilient. It is used It will grow on many sites unfavorable for other for making paper, for construction lumber, and for species, such as organic soils overlying rocks in musical stringed instruments. Its many uses rival mountainous locations, steep rocky slopes, thin soils, those of eastern white pine (Pinus strobus) (21). and wet bottomland (26). On poorly drained soils, lack of aeration limits growth (22). Habitat In the northern part of its range, red spruce (fig. 2) grows at elevations from near sea level to about Native Range 1370 m (4,500 ft) (22). In the southern Appalachian Mountains it comes in at elevations as low as 1370 The range of red spruce (fig. 1) extends from the m (4,500 ft) and from there to about 1520 m (5,000 Maritime Provinces of Canada west to Maine, ft) it is mixed with hardwoods and eastern hemlock southern Quebec, and southeastern Ontario, and (Tsugu canadensis). At 1520 m (5,000 ft) balsam fir south into central New York, eastern Pennsylvania, (Abies balsamea) joins with red spruce to form the northern New Jersey, and Massachusetts. It also dominant spruce-fir climax type. In West Virginia, grows south along the Appalachian Mountains in ex- spruce-fir stands are found as low as 980 m (3,200 treme western Maryland, and eastern West Virginia, and north and west in Virginia, western North Carolina, and eastern Tennessee. Discontinuous stands may also be found in Haliburton Township, in Algonquin Provincial Park, and near Sturgeon Falls in Nippising Township, and in the southwestern Parry Sound District in Ontario, Canada. Climate Red spruce grows best in a cool, moist climate. The climate of the northeastern part of its range can be summarized as follows: annual precipitation (total), 910 to 1320 mm (36 to 52 in); annual snowfall, 203 to 406 cm (80 to 160 in); days with snow cover, 100 to 140; January temperature, -7” to -1” C (20” to 30” F) maximum and -18” to -13” C (0’ to 8” F) mini- mum; July temperature, 21” to 27” C (70” to 80” F) maximum, and 11” to 14” C (52” to 58” F) minimum; frost-free days, 90 to 150 (28). Red spruce attains maximum development in the higher parts of the southern Appalachian Mountains where the atmos- phere is more humid and the rainfall heavier during the growing season than in other parts of its range (47). Local extension of the range of red spruce, as along the southern Maine coast, is related to marine exposure, which provides a cool growing season and ample moisture supply (8). Soils and Topography The soils where red spruce and its associates grow are mostly acid Spodosols, Inceptisols, and some- times Histosols with a thick mor humus and a well- defined AZ horizon-characteristics commonly as- sociated with abundant rainfall, cool climates, and softwood cover (11). Commonly, the pH of these soils ranges from 4.0 to 5.5. In northern New England, red Figure Z-A red spruce stand. 251 Picea rubens ft). Above 1890 m (6,200 ft) in the southern Ap- Carolina include Hylocomium I Oxalis on north-facing palachians, red spruce appears less frequently than slopes above 1520 m (5,000 fit), OxczlislDryopteris at Fraser fir (Abies fraseri) (47). In the White Moun- high elevations and all exposures, and the best site tains of New Hampshire, balsam fir is the type for red spruce and Fraser fir, Viburnum IV&c- predominant species above 1220 m (4,000 ft) but red CiniumlDryopteris (47). spruce is well represented from about 790 to 1010 m The Oxalis / Cornus association is considered the (2,600 to 3,300 ft) (27). best for growing conditions in the northern part of the range. On these sites the soil is rich enough for Associated Forest Cover red spruce but not fertile enough for the tolerant hardwoods to offer serious competition (22). Pure stands of red spruce comprise the forest cover type Red Spruce (Society of American Foresters Type Life History 32). Red spruce is also a major component in 5 and a minor component in 13 other forest cover types Reproduction and Early Growth (10): Flowering and Fruiting-Red spruce is monoe- 5 Balsam Fir cious; male and female flower buds open in May in 12 Black Spruce axils of the previous year’s shoots on different 16 Aspen 17 Pin Cherry branches of the same tree. The pendant male flowers 18 Paper Birch are bright red; female flowers are erect and bright 21 Eastern White Pine green tinged with purple (21). Although cone buds 22 White Pine-Hemlock differentiate as early as July preceding flowering in 23 Eastern Hemlock the following spring, they are difficult to distinguish 25 Sugar Maple-Beech-Yellow Birch until September. For experienced workers they pro- 30 Red Spruce-Yellow Birch vide a possible means of identifying seed years at 3 1 Red SpruceGugar Maple-Beech that time. The cones mature from about mid-Septem- 33 Red Spruce-Balsam Fir ber to early October, the autumn following flowering 34 Red Spruce-Fraser Fir 35 Paper Birch-Red Spruce-Balsam Fir (41). Cones are 3 to 4 cm (1.3 to 1.5 in) long, light 37 Northern White-Cedar reddish brown, with rigid, rounded scales often 60 Beech-Sugar Maple slightly toothed on the edges. Cones are receptive to 107 White Spruce pollen when fully open, a condition which lasts for 108 Red Maple only a few days. Some of the shrubs associated with red spruce are: Seed Production and Dissemination-Good blueberry Naccinium spp.), hobblebush (Viburnum seed crops occur every 3 to 8 years, with light crops lantanoides), witherod (v; cassinoides), rhodora during intervening years (22). Red spruce cones (Rhododendron canadense), lambkill (Kalmia angus- number about 140/liter (5,OOO/bu), which yields 454 tifoliu), mountain-holly (Nemopanthus mucronata), to 680 g (1.0 to 1.5 lb) of seeds. The number of speckled alder (Alnus rugosa), red raspberry (Rubus cleaned seeds per kilogram ranges between 220,000 idaeus var. strigosus), creeping snowberry (Gaul- and 637,000 (100,000 and 289,000/1b), with an theria hispidula), wintergreen (G. procumbens), fly average of about 306,000 (139,00O/lb) (41). honeysuckle (Lonicera canadensis), gooseberry (Ribes Red spruce seeds fall about 1.2 m (4 ft) per second spp.), witch-hazel (Hamamelis virginiana), downey in still air; the following formula determines distance serviceberry (Amelanchier arborea), beaked hazel of travel for wind-disseminated spruce seeds at (Corylus cornuta), and Canada yew (Taxus canaden- various heights (47): sis). (1.47~) A number of mosses and herbs are also found D = Sh growing in red spruce forest types. Certain mosses, Where D = distance in feet which seed will travel, S herbs, and shrubs, however, have been shown to be = number of seconds required for seed to fall from a related to site quality of red spruce (22). The three height of h (ft) on a tree, and u = velocity of the main associations, Hylocomium I Oxalis, Oxalis /Car- prevailing wind in miles per hour. nus, and Viburnum/OxaZis, in that order, indicate Randall (37), in a study of seed dispersal into clear- increasing site productivity and increasing hardwood cut areas, stated that at a distance of 100 m (5 chains competition. Similar site types in the higher eleva- or 330 ft) from the timber edge, the number of spruce tions of the Appalachian Mountains of North seeds trapped were more than adequate for regenera- 252 Picea rubens tion in a g00a seed year and adequate in an average in many ways and are controlled by the same factors, year. Most of the spruce in the surrounding stands but as a rule spruce is the weaker, slower growing was red spruce. species during the establishment period (22). Seedlings that have attained a height of about 15 Seedling Development-Most red spruce seeds cm (6 in) can be considered established. Once estab- germinate the spring following dispersal; some, how- lished, their early growth is determined largely by ever, may germinate in the fall soon after dropping the amount and character of overhead competition. from the tree. Germination is epigeal. On favorable Dense growth of bracken (Pteridium aquilinum), seedbeds the usual spring germination period is from raspberry, and hardwood sprouts are the chief com- late May to early July. On duff, which is more subject petition for seedlings on heavily cutover lands; but to surface drying than most other seedbed materials, red spruce survives as much as 145 years of suppres- some seeds may lose viability by midsummer, and sion and still responds to release (11,391. some may show delayed germination well into Compared to its associates, red spruce is one of the August (22). Little if any viable seeds remain in the last species to start height growth in the spring, forest floor beyond 1 year (13). usually beginning the first week in June and ending Adequate moisture is the chief factor controlling 9 to 11 weeks later.