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Great Basin Naturalist Volume 43 Number 4 Article 24 10-31-1983 Range extensions for two dwarf mistletoes (Arceuthobium spp.) in the southwest Robert L. Mathiasen Northern Arizona University, Flagstaff, Arizona Kenneth H. Jones New Mexico State University, Sunspot, New Mexico Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation Mathiasen, Robert L. and Jones, Kenneth H. (1983) "Range extensions for two dwarf mistletoes (Arceuthobium spp.) in the southwest," Great Basin Naturalist: Vol. 43 : No. 4 , Article 24. Available at: https://scholarsarchive.byu.edu/gbn/vol43/iss4/24 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. RANGE EXTENSIONS FOR TWO DWARF MISTLETOES {ARCEUTHOBIUM SPP.) IN THE SOUTHWEST Robert L. Mathiasen' and Kenneth H. Jones' Abstract.— A second small population of white fir dwarf mistletoe, Arcetithobimn ahietiniim f. sp. concoloris, is reported from the Santa Catalina Mountains in southern Arizona. The discovery of a second population of this mis- tletoe in southern Arizona supports the contention that it once had a more southern distribution but has survived past climatic changes in only a few locations in the southwestern United States. The distribution of the Western spnice dwarf mistletoe, Arceuthohium micwcarptim, is extended to the Sacramento Mountains of south central New Mexico, a range extension of approximately 170 miles. The mistletoe is restricted to an area of about 300 acres, but its potential for further spread is high. The possible implications of this range extension to the biosystematics of Picea spp. and the evolution of A. microcarptim are discussed. White fir dwarf mistletoe, Arceuthobium This paper reports isolated populations of A. abietinum Engelm. ex Munz f. sp. concoloris abietinum from the Santa Catalina Moun- Hawksw. & Wiens, is a serious pathogen of tains in south central Arizona and of A. mi- white fir, Abies concolor (Gord. & Glend.) crocarpum from the Sacramento Mountains Lindl., in the western United States (Scharpf in south central New Mexico. 1964, Scharpf and Parmeter 1967). Hawks- In 1979 a very small population of A. worth and Wiens (1972) hst the distribution abietinum was discovered parasitizing white of this dwarf mistletoe from southern Wash- fir in the Santa Catalina Mountains of Pima ington southward through the Cascade Range County, Arizona (Fig. 1). The population oc- and Sierra Nevada to the San Bernardino curs in an area of about 10 acres in Marshall Mountains in southern California, with four Gulch (T. 12 S., R. 16 E., Section 6) near the isolated populations known: the Charleston center of the mountain range at elevations of Mountains and Spring Creek Mountains, Ne- 2,310 to 2,340 m. The predominant tree spe- cies in vada; Kane County in southwestern Utah; the infested stand are white fir, and Grand Canyon National Park, Arizona. Douglas fir (Pseudotsuga menziesii [Mirb.] Franco), and southwestern white pine (Pinus More recently it has been reported from the strobiformis Engelm.). Douglas fir dwarf mis- Chiricahua Mountains of southeastern Ari- tletoe {Arceuthobium douglasii Engelm.) also zona, nearly 300 miles south of the Grand occurs in the stand on Douglas fir. Douglas Canyon populations (Mathiasen 1976). fir dwarf mistletoe has rarely been collected Western spruce dwarf mistletoe, Arceutho- on white fir and can easily be distinguished bium microcarpum (Engelm.) Hawksw. & from white fir dwarf mistletoe using shoot Wiens, severely parasitizes Engelmann and morphology (Hawksworth and Wiens 1972). blue spruce, Picea engelmannii Parry and P. This is the second report of a small, isolated pungens Engelm., in the southwestern United population of A. abietinum from southern States (Hawksworth and Graham 1963, Arizona. The first was reported in the Chiri- Hawksworth and Wiens 1972). In Arizona it cahua Mountains, approximately 100 miles is known from the Kaibab Plateau, the San southeast of the Santa Catalina population Francisco Peaks and Kendrick Peak, the (Mathiasen 1976). The Santa Catalina popu- White Mountains, and the Pinaleno Moun- lation of A. abietinum is nearly 260 miles tains (Hawksworth and Wiens 1972). In New south of the Grand Canyon population of this Mexico it has only been reported from the taxon, and no other populations of A. abieti- Mogollon Mountains in the west central part num are known between these localities of the state (Hawksworth and Wiens 1972). (Mathiasen 1976). 'School of Forestry, Northern Arizona University, Flagstaff, .\rizona 86011. 'Sacramento Mountain Laboratory, New Mexico State University, Siinspot, New Mexico 88349. 741 742 Great Basin Naturalist Vol. 43, No. 4 Fig. 1. Distribution of Abies concolor and Arcetithobiiim abietiniim (1-4) in Arizona and New Mexico. Numbers 3 and 4 represent the A. abietinitm populations in the Santa Catalina and Chiricahua mountains, respectively. The discovery of a second population of A. were continuous (Hamilton 1961). However, abietinum in southern Arizona supports the A. abietinum has not been reported from suggestion that A. abietinum had a more Baja California, but may not have survived widespread southern distribution in the past there for the same reasons it has not been re- and only relict populations now exist where ported from more localities in the south- climatic conditions have remained favorable western United States. The discovery of addi- for its survival in the southwestern United tional relict populations of A. abietinum and States (Mathiasen 1976). Both of the southern P. densum subsp. pauciflorum in Mexico or in Arizona populations of A. abietinum occur the mountain ranges with white fir popu- on mesic, north-facing slopes of narrow can- lations between the Grand Canyon and yons at approximately the same elevational southern Arizona would provide more evi- range, and near the lower elevational limits dence concerning the past distribution of of white fir in the Southwest. The occurrence these taxa and their probable migration of an extremely isolated population of the routes into the Southwest. white fir true mistletoe, Phoradendron den- In 1980, a small population of A. micro- sum Torr. ex Trel. subsp. pauciflorum (Torr.) carpum was discovered parasitizing Picea Wiens, parasitizing white fir in the Santa engelmannii in the Sacramento Mountains of Catalina Mountains, may indicate this mis- Otero County, New Mexico (Fig. 2). This tletoe had a more southern past distribution population is approximately 170 miles east also. Phoradendron densum subsp. pauciflo- and slightly south of the nearest known popu- rum has not been found on white fir in other lation of A. microcarpum in the Mogollon mountain ranges in Arizona, but it does occur Mountains of west central New Mexico. Our in the Sierra San Pedro Martir in Baja Cali- surveys over the last two years indicate the fornia, which is farther south than the Santa infestation of A. microcarpum in the Sacra- Catalina populations (Wiens 1964). There- mento Mountains is restricted to three small fore, it may be possible that both of these populations totaling about 300 acres occur- white fir parasites migrated to southern Ari- ring on northern exposures in the general vi- zona along a southern route when Baja Cali- cinity of upper Hay Canyon (T. 17 S., R. 12 fornia and the present mainland of Mexico E., Sections 33-34; T. 18 S. R. 12 E., Sections October 1983 Mathiasen, Jones: Dwarf Mistletoes 743 Fig. 2. Distribution of Picea engehnannii and Arceuthohium microcarpum (1-6) in Arizona and New Mexico. Numbers 5 and 6 represent the A. microcarpum populations in the Pinaleno and Sacramento mountains, respective- ly. Number 7 represents the Chiricahua Mountain population oi Picea engehnannii var. mexicana. 3-4) at elevations ranging from 2,760 to have survived elsewhere in the Sacramento 2,840 m. Our examinations of spruce stands Mountains and in the other mountain ranges in adjacent Spring, Hubbell, Wills, and Sac- with large P. engelmannii populations in ramento canyons have not detected addition- southwestern New Mexico (Little 1971) (Fig. al populations of A. microcarpum. These can- 2). Therefore, the possibility of a more recent yons are similar in elevation and topography introduction of A. microcarpum into the Sac- to Hay Canyon, and their north-facing slopes ramento Mountains would appear more plau- are dominated by a geographically restricted sible than the relict population hypothesis, mixed conifer habitat type {Picea engel- which seems more applicable to the disjunct mannii/Acer glabrum HT) described by Moir populations of A. ahietinum in southern and Ludwig (1979) in which Engelmann Arizona. spruce and Douglas fir are co-dominant over- A more recent introduction of A. micro- story species. In addition, all the areas sur- carpum to the Sacramento Mountains may veyed in the Sacramento Mountains are well then be an example of long-range dis- below the upper elevational limit of 3,100 m semination of a dwarf mistletoe by an avian reported for A. microcarpum (Acciavatti and vector. Hawksworth and Wiens (1972) cite Weiss 1974, Hawksworth and Wiens 1972, examples of dwarf mistletoe distributions that Mathiasen and Hawksworth 1980). There- might be best explained by seed dis- fore, the restriction of A. microcarpum to this semination by avian vectors, and certain in- small an area is anomalous because condi- festation patterns of dwarf mistletoes in con- tions for its spread into adjacent spruce ifer stands are best explained by this means stands appear to be favorable. The apparent also (Hudler et al. 1979). One factor that confinement of this parasite to Hay Canyon must be considered when assessing the possi- may indicate it has arrived relatively recently bilities of long-range dissemination of dwarf in the Sacramento Mountains and did not ac- mistletoes by birds is that Arceuthohium spp. company P.

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