Prediction of Leaf Area in Individual Leaves of Cherrybark Oak Seedlings (Quercus pagoda Raf.)

The prediction of leaf area for cherrybark oak (Quercus pagoda Raf.) seedlings is important for studying the physiology of the species. Linear and polynomial models involving leaf length, width, fresh weight, dry weight, and internodal length were tested independently and collectively to predict leaf area. Twenty-nine cherrybark oak seedlings were grown in a greenhouse for one growing season and a total of 468 leaves were collected. Leaf area was polynomially related with leaf length or width, but linearly related with the cross product of length and width. Average leaf area for flush 3 was significantly greater than those of other flushes. However, variation in leaf area among flushes did not affect the models. Relationship between leaf area and length (or width) was consistent. Since leaf length is easy to measure and does not require destruction of leaves, it can be effectively used to predict leaf area in cherrybark oak seedlings

Comparative Gas-Exchange in Leaves of Intact and Clipped, Natural and Planted Cherrybark Oak (Quercus pagoda Raf.) Seedlings

Gas-exchange measurements, including CO2 -exchange rate (net photosynthesis), stomatal conductance, and transpiration, were conducted on intact and clipped cherrybark oak (Quercus pagoda Raf.) seedlings growing in the field and in a nursery bed. Seedlings in the field, released from midstory and understory woody competition, showed significant increases in gas-exchange compared to non-released seedlings due to increases in light levels reaching seedlings. Concurrently, little difference occurred in the CO2 -exchange rate between intact and clipped seedlings in the released treatment although clipped seedlings maintained a consistently greater rate of stomatal conductance. In order to reduce the high variability of light levels recorded in the field, gas-exchange measurements were conducted on intact and clipped cherrybark oak seedlings growing in a nursery bed under consistent light conditions. Again, no differences were found in the CO2 - exchange rate between intact and clipped seedlings. Furthermore, no differences were found in stomatal conductance and transpiration between intact and clipped seedlings. However, significant differences in gas-exchange were found between first-flush and second-flush leaves regardless of seedling treatment (intact or a sprout). Greater rates of gas-exchange in second-flush leaves can be attributed to developing third-flush steams and leaves

Crown Radius and Diameter at Breast Height Relationships for Six Bottomland Hardwood Species

The relationship between a tree\u27s crown radius and diameter at breast height (DBH) has a variety of uses including forest competition studies, tree crown densities, spacing and stocking relationships, wildlife habitat suitability models, and tree volume estimations. Estimating DBH from mean crown radius (MCR) is of interest to natural resource managers because MCR can be estimated from high resolution digital imagery using remote sensing techniques. DBH is a common tree dimensional characteristic that is used to quantify tree and stand structure. This research presents MCR/DBH and DBH/MCR relationships for boxelder (Acer negundo L.), sweet pecan (Carya illinoensis (Wang) K.Koch), sugarberry (Celtis laevigata Willd.), green ash (Fraxinus pennsylvanica Marsh.), Nuttall oak (Quercus nuttallii Palmer), and American elm (Ulmus americana L.). The linear model, y =a+b * x, provided the best model fit with adjusted r values of 0.567 to 0.855 for the 6 species. Crown radius can be determined from digital imagery and then used to predict DBH

Conceptual Basis for an Index of Forest Integrity for Upland Coastal Plain Ecosystems

Following the recent trend to manage natural resources for sustainability, ecologists, resource managers and policymakers are beginning to think of the management of forest ecosystems in terms of ecosystem health or ecosystem integrity. Biologists are increasingly recognizing that use of chemical assays in assessing the condition of an ecosystem has limited value, and that biological factors, e.g., species diversity and composition, can be useful characters in the analysis of biotic integrity. An index of biotic integrity (IBI) has been developed for riverine ecosystems in the Midwest U.S., using fish species diversity, indicator population analysis, trophic structure assessment, and physiological abnormalities in fish as measurable surrogates for biotic integrity . This paper explores the development of an analogous index of forest integrity (IFI) to be applied to the upland coastal plain forests of southern Arkansas and northern Louisiana. The IFI developed here includes sampling and analysis of population trends of dominant plant taxa, plant species diversity, and horizontal and vertical vegetative structure at midstory, shrub and detritus levels

A 2km-size asteroid challenging the rubble-pile spin barrier – A case for cohesion

The rubble pile spin barrier is an upper limit on the rotation rate of asteroids larger than ~200-300. m. Among thousands of asteroids with diameters larger than ~300. m, only a handful of asteroids are known to rotate faster than 2.0. h, all are in the sub-km range (≤0.6. km). Here we present photometric measurements suggesting that (60716) 2000 GD65, an S-complex, inner-main belt asteroid with a relatively large diameter of 2.3-0.7+0.6km, completes one rotation in 1.9529. ±. 0.0002. h. Its unique diameter and rotation period allow us to examine scenarios about asteroid internal structure and evolution: a rubble pile bound only by gravity; a rubble-pile with strong cohesion; a monolithic structure; an asteroid experiencing mass shedding; an asteroid experiencing YORP spin-up/down; and an asteroid with a unique octahedron shape results with a four-peak lightcurve and a 3.9. h period. We find that the most likely scenario includes a lunar-like cohesion that can prevent (60716) 2000 GD65 from disrupting without requiring a monolithic structure or a unique shape. Due to the uniqueness of (60716) 2000 GD65, we suggest that most asteroids typically have smaller cohesion than that of lunar regolith. Keywords: Asteroids; Asteroids, rotation; Rotational dynamics; PhotometryUnited States. National Aeronautics and Space Administration (Grant NNX12AL26G

Characterization of the Companion to μ\mu Her

$\mu$ Her is a nearby quadruple system with a G-subgiant primary and several low mass companions arranged in a 2+2 architecture. While the BC components have been well characterized, the Ab component has been detected astrometrically and with direct imaging but there has been some confusion over its nature, in particular whether the companion is stellar or substellar. Using near-infrared spectroscopy we are able to estimate the spectral type of the companion as a M4$\pm$1V star. In addition, we have measured the astrometry of the system for over a decade. We combined the astrometry with archival radial velocity measurements to compute an orbit of the system. From the combined orbit, we are able to compute the mass sum of the system. Using the estimated mass of the primary, we estimate the mass of the secondary as 0.32 M_sun, which agrees with the estimated spectral type. Our computed orbit is preliminary due to the incomplete orbital phase coverage, but it should be sufficient to predict ephemerides over the next decade.Comment: 7 pages, 5 figures, Accepted to Astronomical Journa