Alpine Timberlines in the Americas and Their Interpretation

The literature of plant geography has long contained references to the facts that (1) in progressing from the poles toward the equator, alpine timberline increases in elevation above sea level, and that (2) the elevation of this timberline exhibits considerable variation at any one latitude on different mountain systems. More recently a third fact concerning the geography of this vegetation boundary has been documented; the latitude-altitude relationship is not rectilinear

Factors Favoring the Persistence of a Relic Association of Eastern Hemlock in Indiana

Scattered through the deciduous forests of Indiana there are relic colonies of eastern hemlock, Tsuga canadensis. These colonies, with quite an appreciable group of other species, including herbs and shrubs (1), are generally considered as remnants of a previous southern extension of their natural species ranges. After these species had been forced southward by the conditions accompanying the advancing ice caps, their post glacial movements, in keeping pace with the retreating ice masses back to their original climax ranges, were very irregular. Thus, in the course of post glacial reorganization of the vegetation, hemlock as a species resumed its more northerly range found in the Lake Forest which covers the area immediately north of the Great Lakes

The relation of certain ecological factors to the inhibition of forest floor herbs under hemlock

In the region of Turkey Run State Park, Parke county, Indiana, there occurs an abundance of Hemlock, Tsuga canadensis. In this locality the tree is to be found typically along the upper limits of precipitous creek bluffs and along the rims of the sandstone canyons,-- here it is the dominant plant in an edaphic climax. The Hemlock association is a codominant climax with the typical Beech-Maple climax of the region

The Acid Ranges of Some Spring Flowering Herbs with Reference to Variations in Floral Color

It is of common knowledge, derived from even limited field observation, that color in the petals of many of our native flowers is quite variable. Where these variations seem constant, and are accompanied by other characters, taxonomists use color as one of the bases of species differentiation. On the other hand, some species, such as Phlox divaricata, treated in this paper, show gradations in floral color from pure white through blue and lavender to pink; these variations are evidently unaccompanied by other constant characters which might indicate racial differences

Robert Harding Whittaker and the Individualistic Hypothesis

No abstract available

Immediate effects of microclimate modification enhance native shrub encroachment

Shrubs have become more dense and expanded beyond their range all over the world for a variety of reasons including increased temperatures, overgrazing, and alteration of historical fire regime. Native shrubs have been encroaching on Virginia barrier island grasslands for over half a century for unknown reasons. Species composition, soil nutrients, leaf area index (LAI), and ground and air temperature were recorded across the shrub to grass transition and at free-standing shrubs in a coastal grassland in order to determine the effect of shrub encroachment on plant community and microclimate. Species richness was significantly lower inside shrub thickets. Soil water content, organic matter, nitrogen (N), carbon (C), and LAI were higher in shrub thickets and free-standing shrubs compared to grasslands. Summer and fall maximum temperatures were lower and more moderate where shrubs were present. Fall and winter minimum temperatures were highest inside shrub thickets. Native shrubs impact microclimate and species composition immediately upon encroachment. These shrubs lower overall species composition, increase soil nutrients and moisture, moderate summer temperature, and increase winter temperature, which has consequences on a larger scale. As barrier islands are critical for protecting marsh and mainland habitats, understanding this mechanism for shrub expansion is important to predict future encroachment of shrubs and displacement of grassland habitat

The Ecology Of Elevational Positions In Plants: Drought Resistance In Five Montane Pine Species In Southeastern Arizona

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141149/1/ajb213762.pd

Textile Dyeing Using Nanocellulosic Fibers

Disclosed are various embodiments for dyeing a material using a dyed nanocellulose dispersion, thereby reducing or eliminating the need for water in dyeing materials, such as fabrics and textiles. A dyed nanocellulose dispersion or gel may be prepared from wood pulp fibers using a homogenizer and a dye, wherein the dyed nanocellulose dispersion comprises nanosized cellulose fibrils. The dyed nanocellulose gel may comprise an approximate concentration of 0.5% to 6%. The dyed nanocellulose dispersion may be applied to a material, such as a fabric or textile material. The fabric or textile material can be dried resulting in a dyed material

Spectral Reflectance as a Covariate for Estimating Pasture Productivity and Composition

Pasturelands are inherently variable. It is this variability that makes sampling as well as characterizing an entire pasture difficult. Measurement of plant canopy reflectance with a ground-based radiometer offers an indirect, rapid, and noninvasive characterization of pasture productivity and composition. The objectives of this study were (i) to determine the relationships between easily collected canopy reflectance data and pasture biomass and species composition and (ii) to determine if the use of pasture reflectance data as a covariate improved mapping accuracy of biomass, percentage of grass cover, and percentage of legume cover across three sampling schemes in a central Iowa pasture. Reflectance values for wavebands most highly correlated with biomass, percentage of grass cover, and percentage of legume cover were used as covariates. Cokriging was compared with kriging as a method for estimating these parameters for unsampled sites. The use of canopy reflectance as a covariate improved prediction of grass and legume percentage of cover in all three sampling schemes studied. The prediction of above-ground biomass was not as consistent given that improvement with cokriging was observed with only one of the sampling schemes because of the low amount of spatial continuity of biomass values. An overall improvement in root mean square error (RMSE) for predicting values for unsampled sites was observed when cokriging was implemented. Use of rapid and indirect methods for quantifying pasture variability could provide useful and convenient information for more accurate characterization of time consuming parameters, such as pasture composition