Trees for the Southern Great Plains
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survival of certain tree species (Read, Catalpa speciosa, Celtis occidentalis, Trees for the 1964). Large-scale tree plantings were Fraxinus pennsylvanica, Fraxinus made in 1923, 1931, and 1938. The velutina glabra, Gleditsia triacanthos, Southern Great recommendations in this article are Hibiscus syriacus Malus spp., Melia Plains based on survival of those trees until azedarach, Prunus armeniaca, Prunus 1987. Average annual precipitation in cistena, Prunus angustifolia watsonii, the area is 15.66 inches (39.8 cm). Prunus costena, Tamarix hispida, Lynn Ellen Doxon1 and During the years of the study, precipi- Tamarix odessana, Tilia americana, tation ranged from 6.13 inches (15.6 Ulmus americana, and Ulmus Davidi- 2 Rex Kirksey cm) in 1934 to 34.96 inches (88.8cm) ana japonica (Burnham, 1922-1950). in 1941. Tucumcari is in USDA plant These species can be used where short- hardiness zone 6B. Temperatures dur- term plantings are needed or where Additional index words. Chilopsis ing the study ranged from a high of irrigation is available, but should not be linearis, Gymnocladus dioica, Juniperus 108F (42C) in 1939 and 1957 to a considered for long-term use without ashei, Juniperus chinensis pfitzeriana, record low of -22F (-30C) in 1963. irrigation. They would be good choices Juniperus monosperma, Juniperus Average length of the growing season where limited supplemental irrigation pachyphlaea, Juniperus pinchotii, is 188 days, with a range from 136 days could be provided. Weak wood and Juniperus virginiana, Pinus edulis, to 217 days during the study (Kirksey, fruit drop pose problems in the land- Pistacia chinensis, Thuja orientalis, 1987). scape use of some of these species. Ziziphus jujuba Only two Pistacia chinensis trees Recommended deciduous Summary. Between 1923 and 1987, were planted, and both survived for the several tree species were tested for species duration of the study. Although data long-term survival under dryland Only three deciduous species had are too limited to support a recommen- conditions at the New Mexico State good survival rates over the 64 years of dation, the Pistacia chinensis may be Univ. Agricultural Science Center at the study. These were Chilopsis linearis, another good choice for dryland situa- Tucumcari. Of those tested, three Ziziphus jujuba, and Gymnocladus di- tions on the Southern Great Plains. The deciduous species-Chilopsis linearis, oica. These trees can be considered for two surviving trees were among the Ziziphus jujuba, and Gymnocladus landscaping, windbreak, and livestock most-attractive deciduous trees in the dioica- had a survival rate >50%. study. Pistachia chinensis has a rather Among the evergreen species, Thuja shelter plantings. Chilopsis linearisis a gangly form when young, but it grows orientalis varieties Goldspire, Gracil- small, flowering tree related to the lis, Berkman, Baker, and Excelsa had catalpa. Flower colors range from white to be a neat, round-crowned tree, re- good survival rates, as did Juniperus through pink to shades of purple. The sembling an ash with age. Scarlet to ashei, J. chinensis pfitzeriana, J. pachy- flowers are present all summer and crimson fall color is its most spectacular phlaea, J. pichottii, J. monosperma and attract hummingbirds, making it a asset. Some individuals also appear to J. virgiana. These species and vari- desirable addition to the landscape. be resistant to mistletoe. eties can be used successfully in dry- Ziziphus jujuba is a medium-size tree Recommended evergreen land plantings in the Western Great that has glossy green leaves and pro- Plains once established. duces an edible fruit that tastes like a species date when it is ripe. It is a thorny tree, Several varieties of juniper and and formed a thicket under the condi- oriental arborvitae had high survival or more than 100 years, resi- tions of the study. Suckering needs to rates. Two Thuja orientalis varieties, dents of the Western Great be controlled, and dropped fruit re- Goldspire and Gracillis, had 100% sur- F Plains have been planting trees quires cleaning up in the landscape. It vival rates with no dead wood visible in and shrubs to improve living condi- fails to produce fruit in dry years. The 1987. ‘Berkman’ arborvitae had a 90% tions and protect property from cli- average height was 14 ft (4.2 m) under survival rate, and both ‘Baker’ and matic extremes. Early settlers dug seed- the conditions of this study. Gymno- ‘Excelsa’ had survival rates >70%. All lings from streambanks for planting cladus dioica is normally a large tree of these are compact varieties. All ex- around their homesteads. Later, spe- that produces a bean-like seedpod. Its cept ‘Gracillis’ averaged » <10 ft (3 m) cies were imported from other areas. height was limited to an average of only tall and wide under dryland condi- Many of these species were not adapted 10 ft (3 m) by the conditions of this tions. ‘Gracillis’ averaged almost 14 ft to their new environment and did not study. It would benefit from supple- (4.2m) tall and just more than 7ft (2.2 survive. In 1923, studies were begun mental irrigation in dry years if it were m) wide. An unnamed oriental arbor- at Tucumcari, N.M., on the long-term planted as a specimen plant. By 1987, vitae had a survival rate of 51% and was both Gymnocladus dioica and Chilopsis almost 18 ft (5.4 m) tall. Large types, linearis had more than one-third dead such as the unnamed entry, would be New Mexico State University, Las Cruces, NM 88003. wood. This was after 50 to 65 years best for windbreak plantings. In land- 1Extension Horticulture Specialist, Extension Plant Sci- without pruning. Since 1949, the trees scape situations, it should be remem- ence Dept. had received no maintenance at all. In a bered that even the compact varieties 2Superintendent, Agricultural Science Center at landscape situation, regular appropri- can grow to be 10 ft (3 m) wide and/ Tucumcari. ate pruning would be necessary. or 10 ft (3 m) tall over time-adequate The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, Other deciduous species survived space should be allowed in the land- this paper therefore must hereby be marked advertise- for the first 25 years of the study, but scape. ment solely to indicate this fact. were not alive in 1987. These included Juniperus ashei, Juniperus pachy- 440 HortTechnology ● Oct./Dec. 1993 3(4) phlaea, and Juniperus pinchotii all had and had very low survival rates. Juniperus species were dead within 8 years of survival rates of 100%. Juniperus horizontalis douglasii had a survival rate planting. They included Juniperus monosperma had only a 50% survival 60% in the first 4 to 20 years of the communis suecica, Picea glaucu, Picea rate, but all deaths occurred in the first study, but none were alive in 1987. It pungens, Pinus banksiana, Pinus nigra, year after planting. Thus, it appears that may be appropriate for short-term use. Pinus sylvestris, Platanus occidentalis, Juniperus monosperma may be more Since the time ofplanting for these trials, and Shepherdia agentea. These species difficult to establish, but it has a long- many juniper varieties have been devel- are not adapted to the dryland condi- term survival rate equal to the other oped. The ‘Pfitzer’, because of its ma- tions of this study. hardy junipers. Juniperus virginiana ture size, is not now considered among Other trees that survived until was also difficult to establish; it had an the best choices for typical landscape 1987, but at rates <50%, are listed in 84% survival rate after establishment. situations. Some of the newer, smaller Table 1. All of these junipers could be used varieties of Juniperus chinensis might be either as windbreak or landscape trees. considered for home landscaping. Juniperus pachyphlaea has interesting Pinus edulis had low survival rates Literature Cited scaly bark. Juniperus pinchottii has a for the first 2 years, but 75% of those that Burnham, D.R. 1922-l950. Annual reddish-brown fruit, rather than the survived the establishment period were progress reports. Tucumcari Field Station, more-familiar greenish blue. These are still alive at the end of the study. Those Bureau of Plant Industry, USDA. all upright, tree-like junipers and have a that survived had an average height of 19 Kirksey, R.E. 1987. Weather observations somewhat gnarled appearance under ft (6 m) and only 4% dead wood. at the Agricultural Science Center at dryland conditions. Tucumcari, 1905-1985. New Mexico Of the shrub-type junipers tested, Unsuccessful trees Agricultural Experiment Station. Res. Rpt. only the pfitzeriana (‘Pfitzer’) had a Eight species of trees were tested, 621. high survival rate. ‘Pfitzer’ was the only but began to die soon after planting. Read, R.A. 1964. Tree windbreaks for the variety of Juniperus chinensis tested. Each species was planted at least three Central Great Plains. Forest Serv., USDA. One Juniperus sabina variety was tested different times, and most plants of the Agr. Hdbk. 250. HortTechnology ● Oct./Dec. 1993 3(4) 441.