Local and General Above-Ground Biomass Functions for Pinus palustris Trees

There is an increasing interest in estimating biomass for longleaf pine (Pinus palustris Mill.), an important tree species in the southeastern U.S. Most of the individual-tree allometric models available for the species are local, relying on stem diameter outside bark at breast height (DBH) and total tree height (HT), but seldom include stand-level variables such as stand age, basal area or stand density. Using the biomass dataset of 296 longleaf pine trees sampled in the southeastern U.S. by different forestry research institutions, we developed a set of local and general systems of tree biomass equations to predict total tree total above-stump biomass, bole biomass outside bark, live branch biomass and live foliage biomass. The local systems were based on DBH or DBH and HT, and the general systems included in addition to DBH and HT, stand-level variables such as age, basal area and stand density. This paper reports the first set of general allometric equations reported for longleaf pine trees. These systems of biomass equations provide tools to support managers in making management decisions for the species in a variety of ecological, silvicultural and economics applications. The systems can be applied to trees growing over a large geographical area and having a wide range of ages and stand characteristics

Beyond the Bayley: Neurocognitive Assessments of Development During Infancy and Toddlerhood

The use of global, standardized instruments is conventional among clinicians and researchers interested in assessing neurocognitive development. Exclusively relying on these tests for evaluating effects may underestimate or miss specific effects on early cognition. The goal of this review is to identify alternative measures for possible inclusion in future clinical trials and interventions evaluating early neurocognitive development. The domains included for consideration are attention, memory, executive function, language and socio-emotional development. Although domain-based tests are limited, as psychometric properties have not yet been well-established, this review includes tasks and paradigms that have been reliably used across various developmental psychology laboratories

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29

Soil carbon and nitrogen content and stabilization in mid-rotation, intensively managed sweetgum and loblolly pine stands

Intensive forestry has resulted in considerable increases in aboveground stand productivity including foliar and belowground biomass which are the primary sources of soil organic matter. Soil organic matter is important for the maintenance of soil physical, chemical and biological quality. Additionally, sequestering carbon (C) in soils may provide a means of mitigating increasing atmospheric carbon dioxide concentrations. In this study, we examined soil C and nitrogen (N) contents and stabilization in 12-year-old, intensively managed sweetgum (Liquidambar styraciflua L.) and loblolly pine (Pinus taeda L.) stands. The treatments examined include: (1) complete weed control; (2) weed control plus drip irrigation; (3) weed control plus drip irrigation and fertigation; and (4) (pine only) weed control plus irrigation, fertigation, and pest control. C and N stabilization was analyzed sequentially by fractionating the soil samples into six fractions using solutions of increasing density. These fractions represented increasingly stable organic matter pools. There was a trend towards increasing C and N contents with increasing management intensity that increase stand productivity; however, these differences were only significant for soil C content in sweetgum. Across all the sweetgum plots, soil C content generally increased with basal area (BA); no such relationship was found in loblolly pine although its BA was equal or higher than that of sweetgum. Generally, across all depths most C was found in the two lightest and in the heaviest fractions. These results suggest that changes to soil C due to increased forest management intensity which increases forest productivity, when they did occur, mostly did not change the percentages of C among soil density fractions over the 12 years of the experiment suggesting minimal inputs of recalcitrant C into the soil; however, even these transient changes may be still be important if intensive management is maintained over subsequent rotations

Partitioning Longleaf Pine Soil Respiration into Its Heterotrophic and Autotrophic Components through Root Exclusion

Rapid and accurate estimations of the heterotrophic and autotrophic components of total soil respiration (Rs) are important for calculating forest carbon budgets and for understanding carbon dynamics associated with natural and management-related disturbances. The objective of this study was to use deep (60 cm) root exclusion tubes and paired control (i.e., no root exclusion) collars to estimate heterotrophic respiration (Rh) and Rs, respectively, in three 26-year-old longleaf pine (Pinus palustris Mill.) stands in western Georgia. Root biomass was measured in root exclusion tubes and control collars after 102–104 days of incubation and fine root biomass loss from root exclusion was used to quantify root decay. Mean Rs from control collars was 3.3 micromol•CO2•m−2•s−1. Root exclusion tubes decreased Rs, providing an estimate of Rh. Mean Rh was 2.7 micromol•CO2•m−2•s−1 when uncorrected by pretreatment variation, root decay, or soil moisture compared to 2.1 micromol•CO2•m−2•s−1 when Rh was corrected for root decay. The corresponding ratio of Rh to Rs ranged from 66% to 82%, depending on the estimation method. This study provides an estimate of Rh in longleaf pine forests, and demonstrates the potential for deep root exclusion tubes to provide relatively rapid assessments (i.e., ~40 days post-treatment) of Rh in similar forests. The range in Rh to Rs is comparable to other reports for similar temperate coniferous ecosystems

Leaf Physiological and Morphological Responses to Shade in Grass-Stage Seedlings and Young Trees of Longleaf Pine

Longleaf pine has been classified as very shade intolerant but leaf physiological plasticity to light is not well understood, especially given longleaf pine’s persistent seedling grass stage. We examined leaf morphological and physiological responses to light in one-year-old grass-stage seedlings and young trees ranging in height from 4.6 m to 6.3 m to test the hypothesis that young longleaf pine would demonstrate leaf phenotypic plasticity to light environment. Seedlings were grown in a greenhouse under ambient levels of photosynthetically active radiation (PAR) or a 50% reduction in ambient PAR and whole branches of trees were shaded to provide a 50% reduction in ambient PAR. In seedlings, shading reduced leaf mass per unit area (LMA), the light compensation point, and leaf dark respiration (RD), and increased the ratio of light-saturated photosynthesis to RD and chlorophyll b and total chlorophyll expressed per unit leaf dry weight. In trees, shading reduced LMA, increased chlorophyll a, chlorophyll b and total chlorophyll on a leaf dry weight basis, and increased allocation of total foliar nitrogen to chlorophyll nitrogen. Changes in leaf morphological and physiological traits indicate a degree of shade tolerance that may have implications for even and uneven-aged management of longleaf pine

Relationships between climate, radial growth and wood properties of mature loblolly pine in Hawaii and a northern and southern site in the southeastern United States

Production rates of loblolly pine (Pinus taeda L.) in favorable exotic environments indicate that full biological expression of growth potential in loblolly pine has not yet been attained in its native range. In previous work, high productivity in a loblolly pine plantation in Hawaii (HI) was hypothesized to be related to a more favorable climate conducive to year round carbon gain. To better understand the role of climate in limiting loblolly pine growth, relationships between radial growth and climate were examined in mature loblolly pine grown on two sites representing the opposite latitudinal ends of its ecological niche, Mississippi (MS) and North Carolina (NC), and on a third site in Hawaii (HI) representing a more favorable exotic environment. Raw ring widths were detrended and chronologies built for each site. At the northernmost site, ring width index (RWI) was positively correlated to February, April and July temperatures, annual mean temperature of the current and previous year, and annual maximum temperature. In MS trees, the only significant correlation between growth and climate was a positive correlation between RWI and November temperature. Growth at the MS site was likely more impacted by frequent hurricanes. In HI trees, no significant correlations between growth and temperature were observed but RWI was significantly related to precipitation during the dry season, which occurred from May–September. Potential anatomical alterations in the earlywood and latewood transition zones and timing of earlywood and latewood formation were indicated and may account for low ring specific gravity and percent latewood in HI trees. The moderate temperatures at the HI site likely supported high productivity but sensitivity to precipitation in HI trees indicates that reductions in water availability may effect loblolly pine growth even under more moderate temperatures when evaporative demand is low

Spatial Variability Of Soil Respiration In A 64-Year-Old Longleaf Pine Forest

Aims: The objectives of this study were to determine the spatial structure of soil respiration (Rs) in a naturally-regenerated longleaf pine forest and to assess the ecological factors affecting the spatial variability in Rs. Methods: Soil respiration, soil temperature (Ts), and soil moisture were repeatedly measured over 6 days in summer 2012 in 3 semi-independent plots. Edaphic, forest floor, and root variables were measured. Diameters of 338 trees were mapped. Spatial analysis and regression were applied. Results: Soil respiration was spatially autocorrelated across plots (66—92 m), but not within plots (6—34 m). Spatial distributions of Rs were relatively stable from morning through early evening and were decoupled from temporal variation of Ts. Ecological covariates (e.g., soil moisture, bulk density and carbon, litter mass, understory cover, roots, nearby trees) related to the spatial variability in Rs; however, models varied between plots. Conclusions: This study shows the importance of stationary plant and soil factors in determining the spatial, temperature-independent distribution of Rs in a heterogeneous forest. We suggest the need for a better understanding of the complex interactions between the heterotrophic, autotrophic, and physical processes driving Rs in order to better model forest carbon budgets