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The analysis here of 22 volcanic rock samples indicates a diverse set of volcanic rock types (Table 1, Figures 1 through 2).  The obsidian nodules collected from Turkey Ridge rhyolite on the NW side of Cerro Rubio are most definitely derived from the Cerro Toledo Rhyolite (CTR) event based on comparison with a large body of CTR source standards from Rabbit Mountain and the ash flow tuff to the south including "Obsidian Ridge" (see Shackley 2005; Table 2 and 3 and Figure 2 herein).  Using XRF the composition is well within those standards (see Table 2 and Figures 2 and 3).

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Arcyria versicolor (Trichiales: Trichiaceae) is a distinct myxomycete species described by William Phillips in 1877. The genus Arcyria dates back to Linnaeus in 1753 through the species A. denudata. Arcyria sporangia are brightly colored red, yellow, grey or white, mostly stalked, often in large groups easily seen with the naked eye. Approximately 54 species are known, many are common, and distributed worldwide. Collectors often encounter these colorful species on decaying logs as clusters of many sporangia often covering extensive areas. Arcyria versicolor, collected in the Valles Caldera National Preserve located in the Jemez Mountains of north central New Mexico, is a new record for the state. The nomenclatural history of this species is reviewed and the justification for selection of the species name versicolor is discussed. Arcyria versicolor is accepted as the valid species name and A. vitellina a synonym after examination of type specimens. Environmental parameters for coloration are discussed in general for fruiting bodies of Arcyria and more specifically for nivicolous snowbank species. Transitional stages of plasmodial color to mature fruiting body formation are described for Arcyria versicolor. More than 140 specimens of Arcyria versicolor fruiting bodies were examined with light microscopy and in part illustrated with multifocal computer stacked imaging. Higher magnifications were highlighted using scanning electron microscopy. A more complete and accurate species description is provided for Arcyria versicolor. Differences of fruiting body morphology including habit, color, dehiscence, peridial inner and outer surface features, capillitial ornamentation and size, spore color, size, and ornamentation, and stalk spore-like bodies are described and illustrated. Observation of type specimens from the type locality is illustrated, discussed, and nomenclatural evaluation given for the name selected. Mountain myxomycetes are reviewed based on the observations of T.H. Macbride and his early 1914 paper published in Mycologia. Collection data is presented that compares the dark-spored and light spored nivicolous myxomycetes in the French Alps. The history of renown collectors of nivicolous myxomycetes in western mountains of U.S.A. documents the discovery and study of this special ecological group of myxomycetes. This current paper is the first in a series from an ongoing research project entitled Myxomycetes of New Mexico. [ABSTRACT FROM AUTHOR]

Extreme stand density increases have occurred in ponderosa pine forests throughout the western U.S. since the early 20th Century, with adverse implications for growth, physiological functioning, and mortality risk. Identifying primary stressors on large, old overstory trees in dense forests can informmanagement decisions to promote resilience and survival.We tested the impact of stand density increase on overstory tree-ring growth, and the relative influence of water and nitrogen, in an old-growth ponderosa pine forest in northern New Mexico subject to variable density increase. We measured annual tree-ring growth and carbon discrimination in trees before stand density increased, in a climatically-similar period post-density increase, and in recent transition to drought. We expected density-driven water stress to drive reduced tree-ring growth in overstory trees in dense stands.We found reduced growth and higher mortality in dense stands, but nitrogen rather than water constrained growth, as determined by carbon isotope discrimination in tree rings, leaf nitrogen concentration, and soil nitrogen supply. In dense stands, less available nitrogen limited photosynthetic rate, leading to reduced assimilation of intracellular 13C and higher discrimination with low tree-ring growth and a reduced relationship with climate. This unexpected result illustrates that a variety of limiting factors can influence forest dynamics, as density-driven nitrogen limitation interacts with water stress to influence tree growth and physiological functioning. [ABSTRACT FROM AUTHOR]

The increase of tree density in forests of the American Southwest promotes extreme fire events, understory biodiversity losses, and degraded habitat conditions for many wildlife species. To ameliorate these changes, managers and scientists have begun planning treatments aimed at reducing fuels and increasing understory biodiversity. However, spatial variability in tree density across the landscape is not well-characterized, and if better known, could greatly influence planning efforts. We used reflectance values from individual Landsat 8 bands (bands 2, 3, 4, 5, 6, and 7) and calculated vegetation indices (difference vegetation index, simple ratios, and normalized vegetation indices) to estimate tree density in an area planned for treatment in the Jemez Mountains, New Mexico, characterized by multiple vegetation types and a complex topography. Because different vegetation types have different spectral signatures, we derived models with multiple predictor variables for each vegetation type, rather than using a single model for the entire project area, and compared the model-derived values to values collected from on-the-ground transects. Among conifer-dominated areas (73% of the project area), the best models (as determined by corrected Akaike Information Criteria (AICc)) included Landsat bands 2, 3, 4, and 7 along with simple ratios, normalized vegetation indices, and the difference vegetation index (R2 values for ponderosa: 0.47, piñon-juniper: 0.52, and spruce-fir: 0.66). On the other hand, in aspen-dominated areas (9% of the project area), the best model included individual bands 4 and 2, simple ratio, and normalized vegetation index (R2 value: 0.97). Most areas dominated by ponderosa, pinyon-juniper, or spruce-fir had more than 100 trees per hectare. About 54% of the study area has medium to high density of trees (100-1000 trees/hectare), and a small fraction (4.5%) of the area has very high density (>1000 trees/hectare). Our results provide a better understanding of tree density for identifying areas in need of treatment and planning for more effective treatment. Our analysis also provides an integrated method of estimating tree density across complex landscapes that could be useful for further restoration planning. [ABSTRACT FROM AUTHOR]

Drought-caused tree dieback is an issue around the world as climates change and many areas become dryer and hotter. A drought from 1998-2004 resulted in a significant tree dieback event in many of the wooded areas in portions of the Jemez Mountains and the adjacent Pajarito Plateau in northern New Mexico. The objectives of this study were to evaluate and quantify the differences in tree mortality before and after a recent drought in ponderosa pine and spruce-fir ecosystems, and to assess the effect of mechanical thinning on ponderosa pine mortality. Significant increases in mortality were observed in the unthinned ponderosa pine ecosystem. Mortality varied significantly between species and within size classes. Mechanical thinning of ponderosa pines reduced overstory mortality to non-significant levels. A lack of rainfall, snowfall, and increases in daily minimum temperature contributed most to the mortality. Adaptive management, including the use of thinning activities, appear to moderate the impact of climate change on ponderosa pine forests in this region, increasing the long-term health of the ecosystem. The impact of climate change on the spruce-fir ecosystems may accelerate successional changes. [ABSTRACT FROM AUTHOR]

Abstract: Products of the latest eruptions from the Valles caldera, New Mexico, consist of the El Cajete Pyroclastic Beds and Battleship Rock Ignimbrite, a sequence of pyroclastic fall and density current deposits erupted at ~55ka, capped by the later Banco Bonito Flow erupted at ~40ka, and collectively named the East Fork Member of the Valles Rhyolite. The stratigraphy of the East Fork Member has been the subject of conflicting interpretations in the past; a long-running investigation of short-lived exposures over a period of many years enables us to present a more complete event stratigraphy for these eruptions than has hitherto been possible. The volume of rhyolitic magma erupted during the 55ka event may have been more than 10km3, and for the 40ka event can be estimated with rather more confidence at 4km3. During the earlier event, plinian eruptions dispersed fallout pumice over much of the Valles caldera, the southern Jemez Mountains, and the Rio Grande rift. We infer a fallout thickness of several decimeters at the site of the city of Santa Fe, and significant ash fall in eastern New Mexico. In contrast, pyroclastic density currents were channeled within the caldera moat and southwestward into the head of Cañon de San Diego, the principal drainage from the caldera. Simultaneous (or rapidly alternating) pyroclastic fallout and density current activity characterized the ~55ka event, with density currents becoming more frequent as the eruption progressed through two distinct stages separated by a brief hiatus. One early pyroclastic surge razed a forest in the southern caldera moat, in a similar manner to the initial blast of the May 18, 1980 eruption of Mt. St. Helens. Ignimbrite outflow from the caldera through the drainage notch may have been restricted in runout distance due to steep, rugged topography in this vicinity promoting mixing between flows and air, and the formation of phoenix clouds. Lavas erupted during both the ~55 and ~40ka events were largely confined to the caldera moat. Any future rhyolitic eruptions of similar magnitude in the southern or western parts of the Valles caldera will likely affect similar areas. [Copyright &y& Elsevier]

Two primary methods for reconstructing paleofire occurrence include dendrochronological dating of fire scars and stand ages from live or dead trees (extending back centuries into the past) and sedimentary records of charcoal particles from lakes and bogs, providing perspectives on fire history that can extend back for many thousands of years. Studies using both proxies have become more common in regions where lakes are present and fire frequencies are low, but are rare where high-frequency surface fires dominate and sedimentary deposits are primarily bogs and wetlands. Here we investigate sedimentary and fire-scar records of fire in two small watersheds in northern New Mexico, in settings recently characterised by relatively high-frequency fire where bogs and wetlands (Chihuahueflos Bog and Alamo Bog) are more common than lakes. Our research demonstrates that: (1) essential features of the sedimentary charcoal record can be reproduced between multiple cores within a bog deposit; (2) evidence from both fire scarred trees and charcoal deposits documents an anomalous lack of fire since 1900, compared with the remainder of the Holocene; (3) sedimentary charcoal records probably underestimate the recurrence of fire events at these high-frequency fire sites; and (4) the sedimentary records from these bogs are complicated by factors such as burning and oxidation of these organic deposits, diversity of vegetation patterns within watersheds, and potential bioturbation by ungulates. We consider a suite of particular challenges in developing and interpreting fire histories from bog and wetland settings in the Southwest. The identification of these issues and constraints with interpretation of sedimentary charcoal fire records does not diminish their essential utility in assessing millennial-scale patterns of fire activity in this dry part of North America. [ABSTRACT FROM AUTHOR]

Objective: Treeless meadows and parks are widespread but poorly understood features of the montane vegetation of the western USA. These communities frequently form reversed treelines where grassy valleys occur below forested slopes above. Our purpose was to assess the environmental correlates of such treelines, as well as patterns in the composition and diversity of grasslands and forest margins in the Valles Caldera National Preserve. Location: Valles Caldera National Preserve (35°50′-36°00′ N, 106°24′-106°37′ W, 2175-3150 m), Jemez Mountains, New Mexico, USA. Methods: We conducted a gradient analysis based on 200 nested quadrats on transects crossing reversed treelines and spanning the compositional heterogeneity of grasslands. We used cluster analysis and non-metric multidimensional scaling to assess relationships between compositional variation and environmental variables. Results: We found strong, highly significant relationships of the vegetation to gradients in slope inclination, soil texture, moisture, nutrient availability, and nighttime minimum temperatures. Reversed treelines are most strongly associated with shifts in the thermal regime, exhibit weaker relationships with soil texture and nutrient content, and show no relationship with gravimetric soil moisture. Gradients in aspect, soil moisture, and annual mean temperature are associated with compositional variation within grasslands and forest margins. Conclusions: Lower nightly minimum temperatures and fewer consecutive frost-free days resulting from cold-air drainage may prevent tree seedling establishment in valley bottoms via photo-inhibition, tissue damage, or frost heaving. Finetextured soils may also impede tree seedling establishment in valley bottoms. These findings lay the groundwork for experimental and physiological tests of these potential causes of these reversed treelines. [ABSTRACT FROM AUTHOR]

The increasing frequency and severity of wildfires in semi-arid conifer forests as a result of global change pressures has raised concern over potential impacts on biodiversity. Ground-dwelling arthropod communities represent a substantial portion of diversity in conifer forests, and could be particularly impacted by wildfires. In addition to direct mortality, wildfires can affect ground-dwelling arthropods by altering understory characteristics and associated deterministic community assembly processes (e.g., environmental sorting). Alternatively, disturbances have been reported to increase the importance of stochastic community assembly processes (e.g., probabilistic dispersal and colonization rates). Utilizing pitfall traps to capture ground-dwelling arthropods within forest stands that were burned by one or two wildfires since 1996 in the Jemez Mountains of northern New Mexico, United States (USA), we examined the potential influences of deterministic versus stochastic processes on the assembly of these diverse understory communities. Based on family-level and genera-level arthropod identifications, we found that the multivariate community structures differed among the four fire groups surveyed, and were significantly influenced by the quantities of duff, litter, and coarse woody debris, in addition to tree basal area and graminoid cover. Taxon diversity was positively related to duff quantities, while taxon turnover was positively linked to exposed-rock cover and the number of logs on the ground. Despite the significant effects of these understory properties on the arthropod community structure, a combination of null modeling and metacommunity analysis revealed that both deterministic and stochastic processes shape the ground-dwelling arthropod communities in this system. However, the relative influence of these processes as a function of time since the wildfires or the number of recent wildfires was not generalizable across the fire groups. Given that different assembly processes shaped arthropod communities among locations that had experienced similar disturbances over time, increased efforts to understand the processes governing arthropod community assembly following disturbance is required in this wildfire-prone landscape. [ABSTRACT FROM AUTHOR]