Arbutus

The Pacific madrone is a spectacular tree. Its showy bark, flowers and berries along with the gracefully crooked branches inspired Bret Harte to compose a poem about its loveliness (see Parsons 1966). But, alas, they can be difficult to grow. These trees should only be planted in very well drained soils in areas with non-alkaline water. Although generally started from seed, Pacific madrone may also be propagated from cuttings, grafting, or layers.

To start from seed, gather the fruits from the trees when they are ripe—generally from October to December. Soften the berries by soaking them in water and then separate the seeds from the pulp. Completely dry the seeds before storing. Dried seeds may be stored for up to 2 years at room temperature. For best germination, use seeds that have been stratified by pre-chilling for one to two months at 2 to 5 degrees C. Plant the seeds, in either spring or fall, in containers that have been filled with a mix of peat, sand, and gravel. Allow the seedlings to reach at least two feet in height before transplanting. Established trees can live up to 200 years or more and do not transplant well, so select a site where the tree can remain permanently. Choose a place with full sun to partial shade well away from lawns and other plants that require summer watering. Deeply irrigate the seedlings once a month during the summer months until established. Do not splash water upon the trunk or leaves while watering, as the trees are susceptible to fungus that resides in the soil. Once established, the trees will require only infrequent, deep irrigation during unusually dry summers. The trees develop an underground, woody organ called a ‘burl’ that re-sprouts if the stem is destroyed.

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Pacific madrone typically bears flowers in May, but may flower in March and April at low elevations [13,82,92]. It flowers from April to May on the Willamette, Mt Hood, and Siuslaw National Forests of western Oregon [138]. In June, the second-year leaves turn orange to red and begin to fall shortly after the new crop of leaves has fully grown. Bark is shed all summer. Berry clusters ripen in autumn and persist into December [13]. On the Challenge Experimental Forest, Pacific madrone berries mature from mid-September to mid-October [87]. The table below gives generalized seasonal development of southern and northern populations of Pacific madrone.

The following is a representative barcode sequence, the centroid of all available sequences for this species.

Pacific madrone  reproduces mainly by sprouting. Sprouts arise from dormant buds  formed at or just above the root collar and tend to be numerous.  More than 300 sprouts were counted on a single low  10-inch-diameter Pacific madrone stump in the northern Sierra  Nevada.

    Low stumps generally produce more sprouts than  high stumps. High stumps sometimes support undesirable stool  sprouts that form on the edge of the cut surface or, less  commonly, on the vertical portion of the stump between the ground  and the top. Stool sprouts tend to become infected with heart rot  at an early age and are more susceptible, to dieback and death  than sprouts from the root crown. Stool sprouts that survive seem  to grow well, but their longevity is unknown.

    Pacific madrone sprouts grow rapidly. On a site of  medium quality in the Klamath Mountains, 3-yearold sprout clumps  averaged 13 members per clump, 3.1 in (10 ft) in height, and 2.3  in (7.6 ft) in width (22). In the northern Sierra Nevada on a  good site, the annual enlargement of sprout clumps was measured  in both a clearcut and a shelterwood. After 10 years, sprouts  were taller, 6.7 vs 3.0 in (22 vs 10 ft); wider, 3.1 vs 2.1 in  (10.1 vs 7.0 ft); contained more sprouts (15 vs 7); and possessed  more volume, 52.1 vs 19.8 cm³ (1,840 vs 700 ft³) (12).  In both locations, annual growth of 1.5 in (5 ft) on 2- to  5-year-old sprouts was observed for particularly vigorous members  of a clump. Seven years after cutting and burning in southwest  Oregon, dense stands of madrone sprout clumps spaced 2.7 by 2.7  in (9 by 9 ft) had a basal area of about 22 m²/ha (96 ft²/acre),  84 percent cover, and an above-ground biomass of 25,000 kg/ha  (22,500 lb/acre) (9). This rapid early growth, both in height and  crown width, allows Pacific madrone to dominate conifer and shrub  associates for many years. It also means that understory species  of grasses, forbs, and shrubs are quickly excluded from madrone  sprout stands following disturbance (9), in spite of a leaf  canopy that is more open than that of tanoak and giant chinkapin  (Castanopsis chrysophyl1a)  (16).

    New information is available for forecasting site  occupancy of Pacific madrone for up to 6 years after disturbance.  It includes equations that relate width and area of sprout clumps  originating from trees greater than 1 inch d.b.h. to size of  parent stem and time since cutting (28), and equations that  predict potential leaf area and biomass by parent tree diameter  class (7).