Environmental Relationships in Forests of Early 20th Century Coos County, Oregon, Based on Timber Cruise Data

Timber cruise data can provide useful information not available elsewhere. Measurements of timber volume (timber cruises) from the early 20th century for Coos County, Oregon, were used to assess the degree to which tree species distribution and timber volume varied with edaphic and climatic factors. The study area has diverse geology in a moderate maritime climate, and represents an area of forest transition between the Coast Range and the Klamath Mountains. Species distribution was determined from 629 cruised 1-mil (2.59 km(2)) sections, and timber volume from 252 sections of old-growth forest. Most forests were dominated by Douglas-fir (Pseudotsriga menziesii); Sitka spruce (Picea siichensis), although least frequent, had the second-most timber volume. All six commercial conifer species differed substantially in distribution in relation to geography and to environment. Both distribution and volume of grand fir (Abies grcrndis) varied with geologic unit and general soil type: Sitka spruce, with soil and maximal summer temperature (- sign); Douglas-fir, with temperature (+) and summer precipitation (+); western hemlock (71-uga heierophylla), with precipitation (+); PortOrford-cedar (Chamaecyparis lawsoniana), with precipitation (-); and western redcedar (Thuja plicata), with no factor. Importance of Douglas-fir and hemlock increased on geologic units with sediments from inland plutonic sources, which reduced importance of Port-Orford-cedar. Some species varied significantly among soil units within a geological formation, and vice-versa. When choosing which species to plant, these cruise data can supplement or replace guidelines based on plant associations

Flowering Patterns of Understory Herbs 30 Years after Disturbance of Subalpine Old-Growth Forests by Tephra from Mount St. Helens

Premise of research. We sought to determine the role of flowering in recovery of understory herbs from a major disturbance and to determine the effects of plant and environmental factors on flowering patterns. Methodology. We counted flowering and nonflowering shoots in permanent plots eight to 10 times over a 30-year period for all 48 understory herb species in four subalpine old-growth conifer forests that received tephra (aerially transported volcanic ejecta) from the 1980 eruptions of Mount St. Helens, Washington. We defined two measures of flowering and related them to environmental and plant characteristics. Pivotal results. Patterns of flowering varied widely among species both among and within growth forms. Flowering increased with time, especially where it was initially low (for evergreen clonal plants, species that also grow in early seral habitats, and plants in deep tephra and from herb-poor sites). Some significant differences that occurred during the first 20 years disappeared by year 30. Percent of shoots flowering declined as shoot density increased, but the significance of this relationship declined until it became nonsignificant by year 25. There was a significant but weak relationship between the proportion of shoots flowering for a species and its proportional increase in shoot numbers during the 30 years of vegetation redevelopment; some species expanded populations only by flowering, while others became dominant while flowering little. Conclusions. Flowering patterns changed with time; this constitutes an important aspect of successional change. Studies of flowering and other aspects of sexual reproduction are important for understanding mechanisms of succession.This is the publisher’s final pdf. The published article is copyrighted by the University of Chicago Press and can be found at: http://www.journals.uchicago.edu/toc/ijps/currentKeywords: succession, coniferous forest, volcanic tephra, forest herbs, flowering, Mount St. Helen

Leaf-level physiology in four subalpine plants in tephra-impacted forests during drought

Ecological impacts of climate change in the Pacific Northwest may hinge on acclimation to drier summers, highlighting the importance of plant physiological studies in forests. Evaluating dominant forest plant species under old-growth and managed forest conditions is similarly important as timber harvest might change microclimates and alter drought effects on plants. We examined water potential and gas exchange rates of four dominant plant species in understories of subalpine forests of the Pacific Northwest region of the United States during 2015 - a year with drought conditions representative of future climate projections. We examined two conifer species (Abies amabilis Douglas ex J. Forbes and Tsuga heterophylla (Raf.) Sarg.) and two huckleberry species (Vaccinium membranaceum Douglas ex Torr. and Vaccinium ovalifolium Sm.) in old-growth and formerly clear-cut forests at two elevations. Contrary to expectations, we found no evidence of hydraulic stress, and there were no significant differences between old-growth and clear-cut stands, consistent with an edaphic buffering effect in this volcanic landscape. Variation in stem elongation rates among years also indicated the lack of a strong drought response in 2015. Water potential, photosynthesis, and stomatal conductance varied among species and among elevations. In combination, our results help constrain expected physiological activity of understory species in subalpine forests and emphasize the importance of the edaphic context (e.g., tephra deposits) in framing expectations for the responses to drought

Variation in plant moisture stress associated with forest communities in the H. J. Andrews Experimental Forest

Measurement of plant moisture stress of 1-2 m understory conifers was made in "reference stands" on the H. J. Andrews Experimental Forest in 1970-1972. Maximum stress each year (measured between midnight and dawn) is closely correlated with the position of each community along one axis of an ordination of the vegetation. In some stands, stress decreases during rainless periods, for uncertain reasons. Apparently, use of different species in different plots does not, of itself, lead to differences in stresses measured at the plots

Variation in air and soil temperatures in forest communities on the H. J. Andrews Experimental Forest, 1970-1972

Air temperatures at i m and soil temperatures at 2C cm are reported for twenty-one forest stands in the central Western Cascader of Oregon. Records began in 1970 for some stands, in 1971 or 1972 for most. Temperature Growth Index for a stand, based on temperature effects on Douglas-fir seedling growth, varies from 32 to 101, and ordinates the stands similarly for 1971 and 1972. However, the index is not closely related to stand position in a vegetation ordination. A strong nocturnal temperature inversion causes summer minima to increase with elevation up to 1100 m, All lapse rates are low up to 1100 m. Comparisons with studies of montane forests in Arizona and Colorado show that the sites studied here lack the temperature variation, particularly the low minima, characteristic of the other areas.Best copy available

The OpenMolcas Web: A Community-Driven Approach to Advancing Computational Chemistry

The developments of the open-source OpenMolcas chemistry software environment since spring 2020 are described, with a focus on novel functionalities accessible in the stable branch of the package or via interfaces with other packages. These developments span a wide range of topics in computational chemistry and are presented in thematic sections: electronic structure theory, electronic spectroscopy simulations, analytic gradients and molecular structure optimizations, ab initio molecular dynamics, and other new features. This report offers an overview of the chemical phenomena and processes OpenMolcas can address, while showing that OpenMolcas is an attractive platform for state-of-the-art atomistic computer simulations

Belowground morphology and population dynamics of two forest understory herbs of contrasting growth form

Forest understory herbs exhibit a large range of variation in morphology and life history. Here we expand the reported range of variation by describing the belowground structures of two very different species, Xerophyllum tenax and Chimaphila umbellata. We excavated individuals in forests of the Cascade Mountains, Pacific Northwest, USA. Xerophyllum tenax has short rhizomes, but an extensive root system that is exceptionally large among forest understory species. The roots reach 4 m in length and may occupy an area 50 times that of the aboveground canopy. In contrast, Chimaphila umbellata has very small roots, but an extensive rhizome system. The largest plant we excavated had 57 m of connected rhizomes and still had a seedling source. Both species have long-lived individuals but differ in response to disturbance. Based on monitoring of 151 permanent 1 m2 plots in an old-growth forest, X. tenax increased only minimally in density over 40 years following tephra deposition from the 1980 eruption of Mount St. Helens, whereas density of C. umbellata increased substantially. The very different morphology of these two species highlights the large range of variation found among forest herbs, which needs to be considered when examining the forest understory.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Secondary disturbance following a deposit of volcanic tephra: A 30 year record from old-growth forest understory

Forest disturbance is usually described by effects on trees, and small disturbances to forest understory are seldom studied. Nevertheless, effective analyses of succession need to consider both stand-replacing and subsequent “secondary” disturbances in both canopy and understory. We estimated characteristics of 13 types of secondary disturbance in old-growth forest understory, and of canopy cover, after the 1980 tephra (aerially transported volcanic ejecta) deposition from Mount St. Helens, Washington. We sampled 100 1-m2 plots at each of four sites for vegetation change and types of disturbance at ten times from 1980-2010; we sampled tree canopy above each plot in 1980 and 2016. The number of canopy gaps increased 23 % and mean gap dimension 68 % during 36 years, mostly from loss of Abies amabilis. Secondary disturbance in understory affected 1.4 % of stand area per year. The areas affected by soil disturbance and effects of woody litter were similar. Erosion, greater in deep than in shallow tephra, peaked in 1981, whereas most litter-caused disturbances increased after 2000. Less frequent litter-based disturbances covered greater area. Our results differ from conclusions about non-volcanic understory disturbances. Secondary disturbances are variable, need more study, and are likely to affect many other systems.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Data from: Understory succession after burial by tephra from Mount St. Helens

1. Successional change following disturbance is a fundamental ecological process that remains central to understanding patterns in plant ecology. Although succession has been studied for well over a century, understanding of the patterns and processes of change is still inadequate, partly because of the dearth of long-term studies. 2. Here, we use, as a model system, a volcanic disturbance that is widespread and of global relevance. We examine succession in old-growth conifer forest understories following burial by tephra (aerially transported volcanic ejecta) in the 1980 eruption of Mount St. Helens. Using four sites with different initial conditions and amounts of disturbance (tephra burial), we sampled plant communities at years 1, 20 and 36 since the eruption using permanent plots representing two treatments: undisturbed tephra and control plots from which tephra was experimentally removed. By using this long-term data, we were able to gauge change through time and differences between tephra-disturbed and control plots. 3. In tephra-impacted plots, cover reached pre-eruption levels by year 36 except for bryophytes at three sites and shrubs at one site. Cover in control plots also increased significantly for all growth forms except bryophytes, remaining above that on tephra plots at the same site in most situations. Sites generally increased in species richness first, and then gradually increased in evenness and Shannon’s diversity; after 36 years, differences between control and tephra-impacted plots remained at only one site. Community composition was stable in one site and shifted gradually through time at the two other sites, and differences between plot types persisted at one site. Communities change over 36 years could relate to various endogenic and abiotic factors. 4. Synthesis: These data suggest that, while recovery to the pre-disturbance status occurs in some cases, recovery is site-specific. Understory communities can be dynamic, even in old-growth forests, and may still be responding to disturbance over three decades later. Long-term experimental studies are key to understanding succession patterns and generalizations about the importance of initial conditions, disturbance intensity, and the complexity of interactions that determine vegetation change