Christmas Trees and Greenery in Denmark

Christmas T rees and Greenery in Denmark
Production and Tree Improvement

American Christmas Tree Journal. 1999. Vol. 43(2):4-11.

Christmas Tree Geneticist and Extension Leader, respectively
Box 8002, Department of Forestry
North Carolina State University
Raleigh, NC 27695-8002

Market Description

Denmark produces about 6-7 million of the 50 million Christmas trees annually marketed in Europe. Christmas tree and greenery sales in Denmark result in an annual revenue of 600-700 million Danish kroner ($US 98-115 million).

Nordmann (or Caucasian) fir (Abies nordmanniana (Stev.) Spach.) is the primary Christmas tree species grown in Denmark. About 1.5 million Norway spruce (Picea abies (L.) Karst.) and 300,000 noble fir (Abies procera Rehd.) are also marketed.

Denmark's population is approximately 5 million and includes nearly 4,000 Christmas tree growers. Annually, 500,000-700,000 Christmas trees are consumed in the country. The remainder are exported to Germany (60-70%) and other European countries making Denmark Europe's largest Christmas tree exporting country.

The production and export of greenery is also of great importance to Denmark. Noble fir is the premier species of the Danish greenery industry. Currently, the revenue from Danish greenery sales is approximately one fourth that from Christmas trees.

While greenery production is expected to remain relatively stable in the future, Christmas tree production in Denmark is expected to double in the next ten years, considering current planting estimates. To accommodate this increased production, new Danish markets in mainland Europe will need to be developed, most likely at the expense of species with poorer needle retention ability such as Norway spruce and Scots pine (Pinus sylvestris L.).

Acknowledgements

The authors recently had the fortunate opportunity to visit Denmark and learn about its Christmas tree industry and research efforts. They visited the Danish Forest and Landscape Research Institute (DFLRI) which is a national agency with the objective of generating and disseminating knowledge on forest, landscapes and planting. One of the five departments of the Institute is the Department of Christmas Trees and Greenery. The authors wish to express their gratitude to department head Kaj Østergård, geneticist, Ulrik Nielsen and nutrionist, Clus Christensen for their warm hospitality and eagerness to share information. The authors also visited Langesø, an estate foundation that manages forest land and Christmas tree plantations. This foundation is highly supportive of the research efforts of the DFLRI. The authors express their thanks to Finn Jacobsen of Langesø for his gracious hospitality.

Increased production by Denmark and other European countries is likely to result in stable or decreasing Christmas tree prices and an even greater emphasis on product quality in European markets.

Products and Cultural Methods

Christmas Trees

Due to differences in traditions, American and European tastes in Christmas trees are vastly different (Table 1). As opposed to the medium and high density trees generally preferred in the United States, Europeans prefer Christmas trees with open natural-grown branch structures (Figure 1).

Table 1. Comparison of desirable traits for an idealized natural-grown low density European and a medium to high density sheared American Christmas tree.
Trait	Europe
Growth	Slow	Fast
Crown Density	Low to Medium	Medium to High
Internodal Branches	Many	Many
Crown Diameter	Small	Large
Branch Angle	Slightly Above Horizontal	Preferences Vary

Christmas trees are often decorated with candles that require gaps between branch whorls, particularly in the upper part of the tree. Consequently, shearing is not generally used or only used sparingly as a cultural practice. In the United States, faster growing trees generally respond better to shearing and result in a fuller tree, however, Danes favor slow growing trees with abundant internodal branching.

Branches growing upward at less than a 90^o angle from the main stem are also desirable so that the internodal stem segments are partially covered. In the United States, medium to wide crown diameters are generally preferred since they fill in better after shearing and allow more flexibility in setting the shearing cone angle.

Narrow to medium crown diameters are favored in Europe to better fit into the typical small rooms where trees are displayed and for families to encircle with held hands during traditional ceremonies. Danes refer to the sheared high density trees commonly grown in the United States as "Donald Duck" trees alluding to the Christmas tree featured in the Walt Disney cartoon broadcast there every Christmas season.

Production of Nordmann fir Christmas trees in Denmark begins with the establishment of either 2-1, 2-2 or 3-0 transplants. Planting densities vary but 4 ft. x 4 ft. is typical. Shearing is not generally done although judicial pruning may be employed to correct a deformity.

Figure 1. Nordmann fir Christmas trees marked for harvesting. First quality class trees (red flags) have uniform and close branch whorls while second quality class trees (blue flags) may have less uniform and wider gaps between whorls.

Danes are careful not to over-fertilize Christmas tree plantations, not only to avoid undesirable rapid growth, but also to ensure that run-off into waterways is minimized. Due to these environmental concerns, a limited number of pesticides are used on Christmas tree plantations in Denmark. Fertilization research is currently underway but the standard recommendation is to apply 62 lbs. nitrogen per acre per year. This is usually applied either as NPKS 23-3-7-4 or NPKS 14-3-18-4.

Despite the preference for slow growth, Danish Christmas tree rotations range from 6 to 11 years since height growth is not lost due to shearing. Typically, only 50 percent of a Nordmann fir Christmas tree plantation would be suitable for the discriminating European market. However, boughts from non-marketable trees are usually harvested and marketed.

Retail trees are often netted twice; once in the field and again at the display lot after sale. Average Nordmann fir Christmas tree retail prices range from $US 4.00 - 5.50 per ft.

Greenery

Decorative uses and production of greenery in Europe areis also different from the United States. In addition to wreaths, table and mantle decorations, greenery is often used for grave coverings. In many parts of Europe, particularly in Germany, graves are covered with conifer greenery from November until spring when flowers and other natural plant coverings become available.

Danish boughs are sold in bundles of 11 lbs. (5 kg) or 20 lbs. (9 kg) (Figure 2). These bundles usually contain 5 to 10 boughs with quality boughs selling for $US 0.45-0.68/lb. The popularity of greenery decorations has resulted in the development of a strong market for fir boughs with a sophisticated system of classifying material.

Figure 2. Bundles of noble fir boughs are often sold in 11 lbs. (5 kg) bundles containing from 5 to 10 branches

Boughs are classified and priced according to various attributes including color (silver, blue, green), tree position (shade versus full light) and tree age (juvenile versus old). Each type is best suited for a specialized type of decorating or economic value. Generally, the older the tree and the higher the position of the branches, the better the bough quality is due to improved branch structure, needle projection (coverage) and color (blue or silver versus green). Boughs from noble fir are considered highly desirable and preferred mostly for indoor decorations. Nordmann fir is also desirable but mostly for outdoor use.

Boughs are often harvested from juvenile trees including non-marketable Christmas trees. Trees are managed specifically for bough production by harvesting the lower branch whorls but leaving the internodal branches and the inner most pair of lateral shoots of each whorl branch. These form a narrow "skirt" around the lower stem with a natural crown around the upper stem.

As the tree grows in height, quality boughs for wreaths are harvested from the skirt while branches for other decorative purposes are harvested from the lower parts of the natural crown. The skirt moves up the tree as it grows in height. The skirt areas can be as high as 20 ft.or more. Trees may be worked for bough production for up to 45 years.

Tree Improvement

Nordmann Fir

Nordmann fir is the preferred Christmas tree species tree in Denmark and much of Europe. This species is native to the Caucasus mountains and the northeastern portion of Turkey surrounding the eastern end of the Black Sea. It occurs at elevations from 3,000 to 7,270 ft. and was introduced into Denmark in the 1850s as an ornamental and potential timber species.

Selection and use of seeds from adapted trees proceeded for about 100 years before concerted provenance testing and breeding efforts began. These efforts have produce a Danish land race of Nordmann fir. (A land race is a group of individual trees of an exotic species introduced and adapted to a specific environment.)

The oldest Nordmann fir seed orchard in Denmark was established in 1967-1969 and is currently in full seed production. This orchard, which was grafted onto European silver fir (Abies alba Mill.) rootstock, is comprised of 23 clones selected from the Danish land race for quality bough production. However, material grown from this orchard has fast growth rates and is early to medium for initial flushing date.

Generally, this material is not optimally suited for Danish Christmas tree production and use of seeds from this orchard will be phased out as new seed orchards come into production. After appropriate testing, this source may be useful in the United States for Christmas tree production involving shearing regimes.

Subsequent to establishment of the first seed orchard, the Danes learned that the Ambrolauria source from the Republic of Georgia (formerly, of the Soviet Union) yielded the slow growth and uniform natural architecture desired by the European Christmas tree consumer. Actually, seeds from this source can be quite variable since elevations can range from 3960 to 5120ft.

Ambrolauria has been widely touted as the best source of Nordmann fir in the United States, however, most Americans do not realized that this is based on the European preference for slow growth. In reality, other faster growing Nordmann fir sources are likely to be preferable for culture under an American shearing regime.

Currently, a new Danish Nordmann fir seed orchards are being established consisting primarily of parent clones tested from sources of the Danish land race. Younger plus-tree materials primarily from Ambrolauria sources of the Danish land race are selected at Christmas tree height and grafted into other orchards. Presently, a total of 86 acres of seed orchard are established.

High grafting onto existing plantation trees is the preferred method of orchard establishment. These and future seed orchards are targeted to meet 50-75% of the future Danish Nordmann fir Christmas tree regeneration. In addition to growth and form, Danes are evaluating adelgid (Adelges spp.) resistance and post-harvest needle retention of their select material (Figures 3 and 4).

Figure 3. Senior researcher and geneticist, Ulrik Nielsen beside an outdoor growth chamber used to test post-harvest needle retention.

Figure 4. Nordmann fir branches from three test trees with varying degrees of needle retention.

Recent provenance tests have revealed that Turkish or bornmüller fir, may perform as well or better then the Ambrolauria source of Nordmann fir under some growing conditions in Denmark, particularly on sites with a low risk of spring frosts. Turkish fir occurs in a population disjunct from Nordmann fir at high elevations in northwestern Turkey.

The classification of Turkish fir is under dispute. It is either classified as a separate species (Abies bornmuelleriania Mattf.) or as a variety of Nordmann fir (Abies nordmanniana var. bornmuelleriania). Nevertheless, morphological differences between these two taxa are slight and not likely to be noticed by the average Christmas tree consumer.

Noble Fir

The silvery and blue foliage of noble fir is highly prized by the Danes for bough production. Relatively few noble firs are sold as Christmas trees since the leader often is damaged by frost and the desired uniform natural shape cannot be achieved.

Noble fir naturally occurs in the Cascade Range and Coast Ranges of the North American Pacific Northwest at elevations ranging from 3,000 ft. to 5,500 ft. It was introduced into Denmark in the 1850s as an ornamental tree and eventually tested and used as a timber species. The original and subsequent early introductions are believed to be a combination of imports from Scotland and direct imports from the United States.

Today noble fir is planted in all parts of Denmark but it grows best on sheltered sites with moraine soils and performs poorly on clayey and poorly drained soils.

In the early 1990's, the Danish Forest and Landscape Research Institute began a breeding program for noble fir that integrates earlier efforts of smaller private programs. Today about 150 select trees are being evaluated in progeny tests and approximately 32 acres of seed orchard have been established.

One focus of the breeding program has been current season needle necrosis, a poorly understood reddening of the needles. Current season needle necrosis is also a problem with noble fir in the United States. Tests have shown that provenances of the Danish land race display significantly lower rates of current season needle necrosis. This trait apparently is under a moderate degree of genetic control making further improvement through selection and breeding likely.

Conclusion

The Christmas tree and greenery industry in Denmark is strong and expected to increase in the near future. The type of product, genetic material and production regimes are considerably different than those most commonly employed in the United States.

United States growers may be able to benefit by using Danish seeds of Nordmann or noble firs but knowledge of the differences between the Danish and American Christmas tree industry and further testing under local conditions are necessary to ensure that the appropriate material is selected.

Additionally, the utility of the Danish system for producing and marketing boughs deserves further examination. This system may allow U.S. greenery producers to reduce costs and to develop new market niches.

Used by permission of American Christmas Tree.