Pinyon Woodland Research Articles

Ecological partnership: Restoring Pinyon woodlands on the Navajo Nation, USA

Pinyon woodlands in the semi-arid southwestern United States developed in response to environmental factors and historical human interactions, providing sustenance and traditional ecological benefits to Native Nations, such as the Navajo (Diné). Historically, Diné communities practiced land stewardship through seasonal movements and resource management, ensuring ecosystem resilience. However, the constraints imposed by European colonization led to transformative changes in their livelihoods and environments. Encompassing 71,000 km2, pinyon-juniper woodlands comprise 89 % of forested area on the Navajo Nation reservation, providing crucial ecosystem services and cultural resources. Since reservation establishment in 1868, increased tree density has diminished understory plant communities and elevated woodland susceptibility to wildfires, compromising overall forest health. Recognizing the imperative for ecological restoration, a collaborative effort between Diné College and Northern Arizona University (NAU) was established in 2018 to develop a pinyon woodland research site on the Diné College campus in Tsaile, Arizona, on the Navajo Nation reservation. We assessed the effectiveness of restoration thinning treatments in reinstating historical woodland structure, modifying fuels for fire mitigation, and engaging students in ecological practices. Thinning resulted in a 62 % reduction in tree density and a 25 % reduction in basal area, altering the woodland structure to reflect historical conditions more accurately. This alteration mitigated the risk of high-intensity wildfires while preserving the age structure of older trees (oldest dating back to 1435 C.E.). Forest floor fuels were low throughout the study, as thinned wood was removed, and activity fuels were immediately treated with chipping. The active participation of Diné College and NAU students, interns, and faculty throughout the study contributed to a cohesive approach in advancing our goals. The comprehensive training empowered students to contribute meaningfully to fieldwork and data collection, aligning with Diné College's mission to enhance post-secondary student learning and development for the benefit of the Diné. By integrating contemporary and culturally sensitive perspectives, our study sheds light on the effectiveness of restoration thinning treatments, emphasizing the delicate balance between ecological resilience and cultural preservation for the Navajo Nation.

Breeding Status of the Gray Vireo on the Baja California Peninsula

Most of the breeding range of the Gray Vireo (Vireo vicinior) lies within the southwestern United States, where the population is sparse, patchy, and declining. But the species also breeds in Baja California, Mexico, where its status has not been assessed. To rectify this, in 2021 and 2022 we surveyed four mountain ranges where the Gray Vireo is known or might be expected. In the northernmost, the Sierra Juárez, we located 43 territories—an abundance strikingly greater than just across the border in Upper California. Territories were in both treeless chaparral dominated by chamise (Adenostoma fasciculatum) and redshank (A. sparsifolium), and in the extensive pinyon woodland. In the Sierra San Pedro Mártir, all 71 territories located were in Adenostoma-dominated chaparral. Extrapolation of the densities observed in these two ranges over the extent of suitable habitat implies the population of the Gray Vireo in Baja California should be over 10,000 individuals. Confirmed by audio recording, one sighting from the Sierra de Ulloa overlooking Ensenada suggests a still wider distribution in Baja California. Isolated stands of chaparral grow south of the Gray Vireo’s previously reported breeding range, on the Sierra La Asamblea. But our reconnaissance of it revealed no Gray Vireos. Survey of the Sierra San Francisco in the center of the peninsula, 3–9 April, revealed only 3 Gray Vireos, all in winter habitat containing Bursera microphylla. Therefore two molting specimens collected in the Sierra San Francisco in October 1997 imply that some individuals molt in the winter range, not a southward extension of the breeding range. Despite Baja California representing only a small part of the Gray Vireo’s breeding range spatially, it contributes disproportionately to the species’ population and therefore conservation.

Ecological factors associated with site occupancy of an endemic chipmunk

ABSTRACTThe Oscura Mountains Colorado chipmunk (Neotamias quadrivittatus oscuraensis) is a rare subspecies of the Colorado chipmunk that is listed as threatened by the state of New Mexico, primarily because it is an endemic subspecies with a small, isolated habitat and the potential for continuing habitat loss. Knowledge about its ecology is limited, which has hindered the development of scientifically defensible management plans. Our goal was to better understand the ecological factors related to the distribution and habitat selection of this chipmunk. We deployed baited camera traps in the Oscura Mountains, New Mexico, USA, using an occupancy modeling framework to determine which ecological factors are associated with occupancy and detection probability. We collected microhabitat and landscape‐level data for use as covariates in the occupancy models. We detected the Oscura Mountains chipmunk at 26 of the 137 survey sites. Occupancy probability was not influenced by the microhabitat characteristics measured and the final model contained only landscape‐level covariates on occupancy. Probability of occupancy was positively associated with proximity to an escarpment, two‐needle pinyon (Pinus edulis) woodland vegetation community type, and elevation. Detection probability was positively associated with the presence of mature two‐needle pinyons at the site. Habitat loss is a major concern for this taxon, especially because climate change is expected to exacerbate threats to pinyon woodlands. Drought, wildfire, bark beetle (Ips confusus) outbreaks, and other diseases pose a large risk to conifer woodlands throughout the southwestern United States. Conserving the pinyon woodlands on the Oscura Mountains, particularly in areas near escarpments, will help maintain habitat that is important for the Oscura Mountains chipmunk. © 2018 The Wildlife Society.

Heliopsis suffruticosa (Compositae, Heliantheae), a new species from western Zacatecas

Se describe Heliopsis suffruticosa de la Sierra de Sombrerete al occidente de Zacatecas, de bosque bajo abierto de piñonero sobre caliza. La especie difiere de otras del género por tener hábito sufruticoso, hojas angostamente lanceoladas a lineares, enteras a espaciadamente serruladas y pedúnculo gradualmente ensanchado hacia el ápice, características que comparte con algunas especies de Zinnia. Se presenta una clave para distinguir entre las especies mexicanas de hábito perenne de Heliopsis. Al igual que en otros representantes de este género, las raíces de H. suffruticosa presentan alcamidas, detectándose en este caso cinco isobutil alcamidas diacetilénicas conjugadas, unidas a un metilo terminal en posición omega.

Factors affecting the floristic relationships among Mexican pinyon woodlands

Factors affecting the floristic relationships among Mexican pinyon woodlands

Flora vascular de la Sierra Monte Grande, municipio de Charcas, San Luis Potosí, México

La Sierra Monte Grande tiene una extensión de 41.8 km2. Se localiza en la zona norte del altiplano potosino; su flora vascular está compuesta por 74 familias, 242 géneros y 397 especies que se encuentran en los siguientes tipos de vegetación: matorrales crasicaule, desértico micrófilo y desértico rosetófilo, así como encinar arbustivo y piñonar. Se consignan 45 registros inéditos para la región del altiplano potosino.

LATE QUATERNARY CHANGES IN PINYON AND JUNIPER DISTRIBUTIONS IN THE WHITE MOUNTAIN REGION OF CALIFORNIA AND NEVADA

Data from packrat middens are used to reconstruct the migration of single-leaf pinyon (Pinus monophylla) and Utah juniper (Juniperus osteosperma) in the White Mountain region of California and Nevada for the last 20,000 years. Today this region is characterized by arid conditions with dry summers. Pinyon woodlands, which are favored by dry summer conditions, are dominant at middle elevations of the White Mountains. The midden record indicates that during the late Pleistocene and early Holocene, juniper was dominant at elevations now occupied by desert shrubs. A late Pleistocene-early Holocene record of desert shrubs was found only in the double rainshadow of the Sierra Nevada and the White Mountains. Pinyon entered the area during the Holocene (ca. 9000 yr B.P.) and subsequently became more important than juniper. During the late Holocene, desert shrubs became established at the lower elevation sites that they now occupy. The late Pleistocene-early Holocene record indicates that there may have been a more...

Packrat Midden Evidence of Late Quaternary Vegetation Change in the White Mountains, California-Nevada

Packrat ( Neotoma spp.) middens from the White Mountains indicate climatic and plant community conditions for the last 19,000 yr. During full-glacial times (ca. 19,000 yr B.P.) and at the Pleistocene/Holocene boundary juniper woodlands were 600 m lower in elevation than at present. Midden assemblages and stable-isotope data suggest lower temperatures and increased precipitation relative to the present into the early Holocene. Two early Holocene middens (ca. 8000 yr B.P.) from lower elevations of the White Mountains contain fragments of pinyon pine and indicate that both pinyon and juniper grew at a site that today supports only a pinyon woodland. Two middle Holocene middens (ca. 5000 yr B.P.) indicate that there was an upward migration of pinyon-juniper woodlands along a high-elevation ecotone, but little change in the middle of the pinyon-juniper woodland. Middens from the late Holocene indicate that present-day plant communities were in place by ca. 2000 yr B.P. or before.

Above-ground biomass and N, P and S capital in singleleaf pinyon woodlands

Above-ground biomass on 11 singleleaf pinyon ( Pinus monophylla Torr. & Frem) woodland sites average 150·5 Mg/ha, of which 60% is tree biomass and 40% the forest floor. The majority of tree biomass (53%) constitutes slash, thus only 28% of the above-ground biomass and 6% of its nitrogen (N) capital is removed as fuelwood. Nitrogen concentration in the forest floor (1·85% N) exceeds that in live pinyon tissue including foliage (1·04% N). Because of its large biomass and high N concentration, the forest floor contains 77% of the above-ground N capital. Site N in soil and above-ground biomass are approximately equal (1178 to 1326 kg/ha), whereas 85 to 87% of phosphorus and sulfur occurs in soils. The nitrogen capital is more at risk from tree harvest and residue management activities than phosphorous or sulfur. In a 100-year rotation, traditional stem wood or whole tree harvest would not appear to adversely impact the N, P and S capital of these sites, but if greater than one-third of the forest floor is lost in burning post-harvest slash, a negative N balance may occur.

Vegetation of Two Relict Mesas in Zion National Park

Twelve permnnent vegetation sampling plots were established on Greatheart and Church mesas in Zion National Park, Utah. Both relict mesas are surrounded by cliffs but contain the same variety of soil conditions as the nearby “msinland.” The mesa vegetation was segregated into the following broad community types: mixed conifer forest, ponderosa pine savanna, Gnmbel oak woodland, pinyon woodland, snowberry-sagebrush steppe, and oak-sagebrush shrubland. Cover of all species was measured in the plots, in addition to tree stem density. Relationships of each community type to topo-edaphicfaetorsnnd response to ta Schmutz et al. 1967; Mason et al. 1967; Kleiner and Harper 1972, 1977a. 1977h). Studies of relict mixed conifer (Abies-Pseudotsugo-Pinus) forest, ponderosa pine (Pinus ponderma) forests or savannas, and Gambel oak (Quercus gambelii) woodlands have apparently been limited to Mason and West’s (1970) report of a brief visit to Timber Top Mesainside the Kolob Section ofZionNational Park(Masonand West 1970). These authors reached this heretofore inaccessible mesa by helicopter and noted fire evidence in the mountain brush community (dominated by Gambel oak), ponderosa pine forest, and Douglas fir (Pseudotsugo menziesii)forest. No wildlife species larger than a chipmunk (Eutamias sp.) were seen on the mesa. Since Timber Top Mesa is bounded on allsides bysheercliffs, it is apparently unvisited by large herbivores like mule deer (Dama hemionus hemionus(Rafinesque)). Thissituationlowersthe value of the vegetation structure for comparison purposes, since it did not develop with the type of browsing pressure that characterized normal “mainland” systems in pre-European times. Mule deer signs have been observed on both mesas in our study. This paper describes the vegetation on Greatheart and Church mesas. Its purpose is to provide a clearer picture of presettlement conditions of mid-elevation plateaus of southwestern Utah. Description of Study Area Greatheart and Church mesas are located in the center of Zion National Park (Fig. 2). Greatheart Mesa is I km west of the Horse Pasture Plateau and is 85 ha (210 acres) in sire. Church Mesa (an unofficial name not yet on USGS maps) lies 2 km south of the Horse Pasture Plateau and 2 km west of the Zion Lodge. Church Mesa is I50 ha (370 acres) in she. The vegetated summits of Greatheart and Church mesas lie between the elevations of 2,160 m (7,092 ft) and 2,259 m (7,410 ft), and 2,150 m (7,058 ft) and 2,254 m (7395 ft), respectively. The higher parts of the mesa tops are capped with limestone from the Carmel Formation. The remainder of each vegetated summit is underlain by sandstone and shales of the Temple Cap Formation (Hamilton 1978). The sheer 150. to 300-m (500 to 1,000 ft) cliffs that circumscribe the 2 relicts are carved from Navajo sandstone. Soils on the ridgetops are in the Paunsaugunt gravelly silt loam series, while the slopes are covered by the deeper Kolob-Detra association. Level areas near the rim of the mesas feature Kinesava fine sandy loam (Madany 1981). Soils of Zion National Park are described in more detail by Mortensen et al. (1977). The mesas are covered by vegetation quite similar in general composition to that of the nearby Markagunt Plateau. Ponderosa JOURNAL OF RANGE MANAGEMENT 37(s), September ,984 Horse Past we Plateau

Seed Reserves in Soils of Successional Stages of Pinyon Woodlands

Seedlings emerging from soil, duff and litter samples from four microsites (duff, transition, interspace, shrub) and four successional stages (grass-forb, shrub-tree, tree-shrub, tree) were recorded for 6 weeks. Seed reserves in soils decreased in number and species diversity from early to late successional stages. Of seedlings emerging, 890% were annuals. The shrub microsite from the shrub-tree stage had the highest total and perennial seed reserves. As shrub cover decreased, the transition microsite between the duff and interspace became the most important source of total seed reserves, and the duff microsite became the most important source of perennial seed reserves. INTRODUCTION The temporal and spatial variation in seed reserves in soils is an important component in modeling succession (Major and Pyott, 1966; Livingston and Allessio, 1968; Kellman, 1970). Previous studies found that seed reserves decline from early to late stages of succession (Oosting and Humphreys, 1940; Olmsted and Curtis, 1947; Quick, 1956; Livingston and Allessio, 1968). In southwestern shruband grasslands, seed reserves are concentrated under or around shrubs and grasses, with few seeds in the barren area in between (Knipe and Springfield, 1972; Nelson and Chew, 1977). Seed reserves also vary with soil depth, with most of the reserves concentrated in the top 2-3 cm of soil (Floyd, 1966; Wesson and Wareing, 1969; Childs and Goodall, 1973; Strickler and Edgerton, 1976). The objective of this study was to determine variation in amounts and species of seed reserves in the soils from various stages of pinyon woodland succession. The most commonly identified stages of pinyon-juniper succession are: (1) annual grass-annual forb stage; (2) perennial grass-perennial forb stage; (3) shrub-perennial grass-perennial forb stage; (4) shrub-perennial grass-perennial forb-young tree stage; (5) mature treeshrub stage, and (6) climax tree stage (Arnold et al., 1964; Erdman, 1970; Barney and Frischknecht, 1974; Stager, 1977; Tausch and Tueller, 1977). In addition, distribution of seed reserves among seedbed components of the woodlands was examined. This seedbed consists of a mosaic of shrub litter, pinyon duff, bare ground (interspace) and transition microsites. SITE DESCRIPTION The study was conducted in April 1979 on the N-facing foothill slopes of the Sweetwater Mountains, 0.5 km SE of Walker, California (T. 8 N., R. 23 E., Sec. 27). The study area has a slope of 15 % and an elevation of approximately 1890 m. Average annual precipitation is 250 mm and mean annual temperature is 9.8 C. The soils are well-drained typic torripsamments of granitic parent material. The area is characterized by variations in understory and pinyon (Pinus monophylla) cover resulting from a combination of past use of wood products, livestock grazing, wildfires and disease or insect attacks. Within a recent burn and adjacent woodland area, four sites in different successional stages were identified as grass-forb, shrub-tree, tree-shrub and tree. The grassforb site is located on the 1973 Rock Creek burn. The burn was aerial-seeded in the 1Stationed at the Renewable Resources Center, University of Nevada, Reno 89512.

Geographic Variation in Eutamias quadrivittatus with Comments on the Taxonomy of Other Arizonan Chipmunks

Analyses indicate that two subspecies of the chipmunk Eutamias quadrivittatus are recognizable. The widely used name E. q. hopiensis is a syno- nym of E. q. quadrivittatus. A new name is proposed for the other subspecies. The cliff chipmunk in northwestern Arizona is Eutamias dorsalis grinnelli, not E. d. utahensis. The least chipmunk in eastern Arizona is Eutamias minimus operarius, with E. m. arizonensis a synonym of this subspecies. Chipmunks of the species Eutamias quadrivittatus consist of two groups: a large-sized, dark-colored form that usually is found in pine or spruce-fir forests of central and southern Colorado, northern New Mexico, northeastern Arizona, and western Oklahoma; and a small-sized, light-colored form that usually is found in open, juniper- pinyon woodlands among rocks in Utah, north-central Arizona, and western-most Colorado. The differences in size, both externally and cranially, are appreciable and probably are more significant than color, which may be quite variable. The zone of intergradation be- tween these groups is a geographically narrow one in western Colo- rado and northeastern Arizona (see Fig. 1). Analysis of chromosomes of the two groups shows no differences (Sutton and Nadler 1969:528) and according to White (1953b:621-622), the western group has a smaller baculum with a more distinct angle between the tip and shaft. The western group of chipmunks presently is called Eutamias quadrivittatus hopiensis, with the type locality at Keams Canyon, Navajo Co., Arizona. Unfortunately, however, specimens from Keams Canyon do not have the small size characteristic of the western pop- ulations and therefore the name hopiensis cannot be used for the western race. A detailed analysis of specimens from Keams Canyon,

Late Quaternary sedimentation and paleoecologic history of Chaco Canyon, New Mexico

A stratigraphic and pollen analytical study of a thick sequence of alluvium at Chaco Canyon National Monument has provided a detailed history of late Quaternary alluviation, channel trenching, vegetation, and climate for the eastern Colorado Plateau. The alluvium at Chaco Canyon consists of five informal units, each separated by an erosional unconformity: Fajada (late Pleistocene), Gallo (7000 to 2400 B.P.), Chaco (2200 to 850 B.P.), Post-Bonito (600 B.P. to 1860 A.D.), and Historic (1935 to present). The Fajada paleosol occurs throughout northwestern New Mexico and is radiocarbon dated as older than 6,700 yr. Pollen analysis of the four younger alluvial units provides evidence for a mid-Holocene interval of aridity that occurs later than recognized elsewhere in the Southwest. Around 5,800 yr ago both pinyon and ponderosa forests were rapidly diminished by a decrease in precipitation. Maximum reduction of the pine forests and woodlands and the greatest aridity of climate persisted from 5600 to 2400 B.P. Ponderosa forests in the mountains adjacent to Chaco Canyon had begun to expand their range by 2200 B.P., and the major expansion of pinyon woodlands in the Chaco area began about 850 yr ago. The climate at Chaco Canyon when the Basketmaker and Pueblo peoples lived there about 600 to 1150 A.D. was drier and warmer than it is today. The ponderosa pine logs used in pueblo building were obtained from the mountains east, south, or west of Chaco Canyon. Abandonment of the pueblos coincided with the incision of the valley floor by the post-Bonito channel system.

Growth Forms in Arctostaphylos glauca

Arctostaphylos glauca has evolved two growth forms in the San Bernardino Mountains of Southern California. A chaparral ecotype of upright shrubs with relatively long leaves occurs in chaparral on the south and west sides of the mountain range. A desert woodland ecotype of low, compact, spreading shrubs with shorter leaves occurs in pinyon woodland on the north and northeast sides of the same range. The chaparral ecotype flowers early and fruits heavily. Upon periodic destruction by fire its populations are replaced by numerous seedlings. The woodland ecotype flowers late and fruits sparingly. Its lower seed reproductive potential is further indicated by the lower total number of floral units, by a lower proportion of fruit set, and by an apparent truncation of the flowering season before all the flower buds open. An alternative strategy, involving long life, compact growth form, and the exploitation of new soil resources by layering and vegetative reproduction in the absence of regular fire recycling has evidently adapted an old chaparral plant to recent desert woodland conditions.

GROWTH FORMS IN ARCTOSTAPHYLOS GLAUCA

Arctostaphylos glauca has evolved two growth forms in the San Bernardino Mountains of Southern California. A chaparral ecotype of upright shrubs with relatively long leaves occurs in chaparral on the south and west sides of the mountain range. A desert woodland ecotype of low, compact, spreading shrubs with shorter leaves occurs in pinyon woodland on the north and northeast sides of the same range. The chaparral ecotype flowers early and fruits heavily. Upon periodic destruction by fire its populations are replaced by numerous seedlings. The woodland ecotype flowers late and fruits sparingly. Its lower seed reproductive potential is further indicated by the lower total number of floral units, by a lower proportion of fruit set, and by an apparent truncation of the flowering season before all the flower buds open. An alternative strategy, involving long life, compact growth form, and the exploitation of new soil resources by layering and vegetative reproduction in the absence of regular fire recycling has evidently adapted an old chaparral plant to recent desert woodland conditions.

POPULATION VARIABILITY OF CERCOCARPUS IN THE WHITE MOUNTAINS OF CALIFORNIA AS RELATED TO HABITAT.

Two species of Cercocarpus occur in the White Mountains of California, a desert range in the east-central part of the state. One, C. intricatus Wats., is confined to steep, rocky limestone slopes primarily within the pinyon woodland (6500 to 9500 feet). The distribution of the second species, C. ledifolius Nutt., is centered at elevations above 9000 feet in the subalpine zone. At most sites of occurrence the populations are quite large and dominate the vegetation. In these areas there is usually little morphological variation between plants and there is no difficulty in assigning an individual to one or the other of the two taxa. There are certain areas, however, where the local populations have individuals representing all degrees of variation between the two species. This study was undertaken to assess the morphological variation of different local populations of Cercocarpus and to relate these to habitat variation.

The Pinyon Woodland Zone in the White Mountains of California

The environment and phytosociological characteristics of the pinyon woodland zone of the White Mountains of California are described and contrasted with those of other southwestern representatives of this vegetation type. The pinyon woodland zone of the White Mts. is floristically allied to Nevada and parts of Utah. The White Mt. zone is unique in the high upper elevation limit it attains (9,500 ft) and in the low amount of average annual precipitation it receives (8 to 12 inches). Apparent fluctuations in population structure of pinyon pine through time are related to grazing history and catastrophic climatic events.