Nursery and Landscape Performance of Ornamental Junipers in the Southern Rocky Mountains

Supplying landscape plants for expanding urban centers in the southern Rocky Mountains provides a solution to limited-resource producers wishing to convert from traditional agricultural crops to higher value horticultural crops in this region. Thirty-five cultivars of ornamental junipers (Juniperus sp.) were planted in an abandoned agricultural field in Mora, N.M. , to evaluate their suitability for nursery production in this region. The plantings were measured after 4 years, and cultivars were ranked for nursery suitability. The planting was then grown for an additional 16 years to examine landscape performance. Nineteen cultivars were considered suitable for nursery production with five cultivars being highly recommended based on survival and growth. Twenty-five of the cultivars were considered suitable for landscape use in the foothill region of the southern Rocky Mountains based on the 20-year measurements. Nine cultivars were classified as highly recommended. Production of ornamental junipers provides an economical alternative to traditional agricultural production systems. The southern Rocky Mountain region has experienced significant population growth since the mid 1970s. Most growth has been in the foothill and lower slope portions of the region in an elevation range of 1,650 to 2450 m (5400 to 8000 ft). In New Mexico, much of this growth has occurred in Rio Arriba, San Miguel, Santa Fe, and Taos counties of north central New Mexico. Population increases in these four counties from 1980 to 1990 ranged from 13.2% in San Miguel County to 31.3% in Santa Fe County (University of New Mexico, 1995). Urban and suburban centers in this region accounted for most of this growth (University of New Mexico, 1994, 1995). The growth trend is expected to continue in these counties over the next several decades with a projected population increase from ≈183,000 to >284,000 in 2020 (University of New Mexico, 1994). These municipalities have expanded into semiarid regions with limited supplies of underground and surface water. To satisfy the increasing demands on these water supplies, most municipalities have employed various water conservation measures, including the required use of xeriscape designs for new residential and commercial developments. Enforcement of these xeriscape ordinances has challenged landscapers and homeowners to design and establish species-diverse landscapes. Many native plants from the lower elevation Chihuahuan and Sonoran Deserts used in xeriscapes elsewhere in the southwest United States are not suited to the colder climates found at these higher elevations. Juniper has been characterized as one of the toughest groups of evergreen landscape plants (Dirr, 1983). Juniper species are ideally suited for landscaping in the foothill region of the southern Rocky Mountains because of their ability to tolerate prolonged drought and wide temperature extremes. Junipers, with a wide range of growth forms, can be used in numerous ways in a landscape, from a ground cover to a solitary tree. In contrast to population growth in urban areas, rural populations of these and adjacent counties have stagnated, and in some cases decreased, over the past three decades (University of New Mexico, 1995). The economy of these rural regions remains largely based in agricultural enterprises, primarily ranching and small agricultural production systems. The marginal profitability of these enterprises has contributed to the overall downturn in these rural economies and the efflux of their residents. The Mora Valley, in north central New Mexico, is typical of many of these rural agricultural communities in the southern Rocky Mountains. Traditionally an agricultural valley, the Mora Valley is currently characterized by small family owned farms. One opportunity to offset the overall economic downturn characteristic of small agricultural enterprises throughout the country is to change from traditional crops such as alfalfa to high value horticultural crops. However, the short, 105-d growing season, the cool night temperatures, a limited water supply, and the distance from large commercial markets combine to exclude most alternative horticultural crops that can be produced economically in these areas. One solution is to produce Christmas trees, which for decades have been harvested from native forests and have provided a significant and ongoing economic enterprise in the Mora Valley (Harrington, 1994). A transition from traditional land uses to Christmas tree production would create a more sustainable and profitable enterprise than is attainable with trees harvested from the forest, but such a transition faces many obstacles. A primary difficulty with conversion to Christmas tree production is its slow return on investment (Gorman et al., 1989). Production of marketable Christmas trees in this valley requires 6 to 9 years, depending on the species and management (Gorman et al., 1989; Harrington, 1994). A potential solution is to produce an interim high value crop, such as ornamental junipers, marketable in the expanding urban and suburban centers of the region. The junipers could be interplanted with the Christmas trees, providing an interim return on investment in 3 to 4 years. Investment in land would remain unchanged, however, plant material costs would be increased. Irrigation costs would remain similar, as most of this area is flood irrigated from surface water sources. Mora Research Center, Department of Agronomy and Horticulture, New Mexico State University, Las Cruces, NM 88003.