Volatile organic compound speciation above and within a Douglas Fir forest

Mixing ratios and fluxes of volatile organic compounds (VOCs) were measured by PTR-MS (and GC-MS) and virtual disjunct eddy covariance during a three-week field campaign in summer 2009 within and above a Douglas fir (Pseudotsuga menziesii) forest in Speulderbos, the Netherlands. Measurements included the first non-terpenoid species fluxes and mixing ratios for Douglas fir canopy. Above-canopy emissions of monoterpenes were comparable to previous studies of P. menziesii, with standard emission factors for the first and second halves of the campaign of 0.8 ± 0.4 and 0.8 ± 0.3 µg gdw-1 h-1, and temperature coefficients of 0.19 ± 0.06 and 0.08 ± 0.05 °C-1, respectively. Isoprene standard emission factors for the two halves of the campaign were 0.09 ± 0.12 and 0.16 ± 0.18 µg gdw-1 h-1. Fluxes of several non-terpenoid VOCs were significant, with maximum fluxes greater than has been measured for other coniferous species. α-Pinene was the dominant monoterpene within and above the canopy. Within canopy mixing ratios of individual species were generally greatest in early evening consistent with reduced vertical mixing and continued temperature-dependent emissions. Acetaldehyde, acetone and monoterpenes had elevated mixing ratios toward the bottom of the canopy (5-10 m) with assumed contribution from the large quantities of forest-floor leaf litter. MBO (2-methyl-3-buten-2-ol) and estragole had peak mixing ratios at the top of the canopy and are known to have coniferous sources. MVK + MACR (methyl vinyl ketone and methacrolein) also had highest mixing ratios at the top of the canopy consistent with formation from in-canopy oxidation of isoprene. The work highlights the importance of quantifying a wider variety of VOCs from biogenic sources than isoprene and monoterpenes

Using tree rings to assess the air quality in Klosters, Switzerland

Tree rings are widely recognised as passive environmental archives able to record the atmospheric composition and reflect the signal of the major pollutants with yearly resolution. This characteristic of trees and its efficacy has been tested in the current investigation. The case study of the village of Klosters was chosen to check the hypothesis that two groups of Norway spruce trees growing in relatively similar environmental conditions but exposed to two different quantities of atmospheric pollution from traffic exhausts, will store a dissimilar amount of pollutants within their tree rings. In order to verify this hypothesis, a combination of multiple analytical techniques was implemented to identify the signal of specific elements and isotopes usually associated with road traffic pollution. The Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was performed to verify the presence and signal of several heavy metals, often found in vehicles exhausts or released by the wear of the engines. The nitrogen isotope analysis gave insights into the concentration of the δ15N isotope, which depending on the emitting sources can be more or less depleted. Finally, the 14C analysis depicted the sites’ dilution effects generated by the emissions of radioactively dead CO2. However, the radiocarbon analysis revealed that in the site exposed to lower quantities of traffic pollution the growth of Norway spruces is limited by the availability of CO2 rather than nitrogen, which is very often the case for most of the forested ecosystems. The results of the three analyses did not reflect the expectations of the initial hypothesis, since changes and differences in traffic volumes do not seem to produce major discrepancies in the recorded data of tree rings. Such lack of response in tree rings is possibly ascribable to the various limitation encountered in the current research for each of the applied method

Individual snag detection using neighborhood attribute filtered airborne lidar data

The ability to estimate and monitor standing dead trees (snags) has been difficult due to their irregular and sparse distribution, often requiring intensive sampling methods to obtain statistically significant estimates. This study presents a new method for estimating and monitoring snags using neighborhood attribute filtered airborne discrete-return lidar data. The method first develops and then applies an automated filtering algorithm that utilizes three dimensional neighborhood lidar point-based intensity and density statistics to remove lidar points associated with live trees and retain lidar points associated with snags. A traditional airborne lidar individual-tree detection procedure is then applied to the snag-filtered lidar point cloud, resulting in stem map of identified snags with height estimates. The filtering algorithm was developed using training datasets comprised of four different forest types in wide range of stand conditions, and then applied to independent data to determine successful snag detection rates. Detection rates ranged from 43 to 100%, increasing as the size of snags increased. The overall detection rate for snags with DBH ≥ 25 cm was 56% (± 2.9%) with low commission error rates. The method provides the ability to estimate snag density and stem map a large proportion of snags across the landscape. The resulting information can be used to analyze the spatial distribution of snags, provide a better understanding of wildlife snag use dynamics, assess achievement of stocking standard requirements, and bring more clarity to snag stocking standards.Keywords: Snag detection, Snag density, Airborne lidar, Forestry, Snags, Neighborhood attribute lidar filtering, Lidar filterin

Plan for the uniform mapping of earth resources and environmental complexes from Skylab imagery. Assessment of natural vegetation, environmental, and crop analogs

The author has identified the following significant results. For interpreting a wide range of natural vegetation analogs, S-190A color infrared and the ERTS-1 color composite were consistently more useful than were conventional color or black and white photos. Color infrared was superior for five vegetation analogs while color was superior for only three. The errors in identification appeared to associate more with black and white single band images than with multiband color. For rice crop analogs, spectral and spatial discriminations both contribute to the usefulness of images for data collection. Tests and subjective analyses conducted in this study indicated that the spectral bands exploited in color infrared film were the most useful for agricultural crop analysis. Accuracy of crop identification on any single date of Skylab images was less than that of multidate analysis due to differences in crop calendar, cultural practices used, rice variety, planting date, planting method, water use, fertilization, disease, or mechanical problems

A comparison of isoprene and monoterpene emission rates from the perennial bioenergy crops short-rotation coppice willow and Miscanthus and the annual arable crops wheat and oilseed rape

Biogenic volatile organic compounds (BVOC) emissions from bioenergy crops may differ from those of conventional crops. We compared emission rates of isoprene and a number of monoterpenes from the lignocellulosic bioenergy crops short-rotation coppice (SRC) willow and Miscanthus, with the conventional crops wheat and oilseed rape. BVOC emission rates were measured via dynamic vegetation enclosure and GC-MS analysis approximately monthly between April 2010 and August 2012 at a location in England and from SRC willow at two locations in Scotland. The largest BVOC emission rates were measured from willow in England, and varied between years. Isoprene emission rates varied between <lod and 1960 μg g−1 h−1. Of the monoterpenes detected from willow, α-pinene emission rates were highest (<lod to 803 μg g−1 h−1), followed by <lod to 268 μg g−1 h−1 for δ-3-carene, <lod to 125 μg g−1 h−1 for β-pinene and <lod to 80.4 μg g−1 h−1 for limonene. BVOC emission rates measured in Scotland were much lower. Low emission rates of isoprene and α-pinene were measured from Miscanthus in 2010 (<lod to 6.42 μg g−1 h−1 and <lod to 20.8 μg g−1 h−1, respectively) but were not detected in subsequent years. Emission rates from wheat of isoprene were negligible but relatively high for monoterpenes (<lod to 422 μg g−1 h−1 and <lod to 104 μg g−1 h−1 for α-pinene and limonene, respectively). No significant emission rates of BVOCs were measured from oilseed rape. The measured emission rates followed a clear seasonal trend. Crude extrapolations based solely on data gathered here indicate that isoprene emissions from willow could correspond to 0.004-0.03% (UK) and 0.76-5.5% (Europe) of current global isoprene if 50% of all land potentially available for bioenergy crops is planted with willow