Characterizing the potential distribution of the invasive Asian longhorned beetle (Anoplophora glabripennis) in Worcester County,Massachusetts

The Asian longhorned beetle (ALB) (Anoplophora glabripennis) is an invasive insect pest that has established populations in Worcester County, Massachusetts as of 2008. ALB predominantly targets red maple (Acer rubrum), sugar maple (Acer saccharum), which are prominent in New England hardwood forests, and Norway maple (Acer platanoides), which was planted in built environments as street trees in response to severe weather and invasive insect and pathogen disturbances. Mahalanobis Typicality models related presence locations of ALB presence-only locations in Worcester County towns from 2008 to 2012 to biotic, abiotic, and anthropogenic variables to predict the potential distribution of ALB and to determine locations most characteristic of infestation. k-fold cross-validation and a continuous Boyce Index were employed to validate model performance and to identify threshold values at which continuous models of typicality could be reclassified into categorical maps. Distance-to-roads (r² = 0.19) and probability of maple presence (r² = 0.13) were the most important predictor variables in the ALB model. Locations that were most consistently susceptible to ALB infestation had significant high maple presence (p < 0.001) and significant low distance-to-roads (p < 0.001) compared to the whole study area, suggesting that ALB in Worcester County, MA, prefers maple-dominant edge habitats at the current stage of invasion. The localized ALB potential distribution model was consistently accurate (Boyce Continuous Index = 0.84) despite the lack of absence locations and incomplete knowledge of ALB niche breadth in both native and invaded ranges. The results from this study could be used as a baseline for effective adaptive management policies that could help prioritize the need for early detection/eradication measures and address the potential ecological and social ramifications of the current ALB outbreak in Worcester County. It is hoped that the model employed could be further tested for future outbreaks as they are discovered in the USA.     

Investigation of lead and zinc dispersion from an abandoned mine site at Tyndrum, Scotland, using tree bark measurements

Tyndrum was an industrial mining area from 1741 until the 1920s where the main ores extracted were lead sulphide （galena） and zinc sulphide （sphalarite）. Situated in central Scotland, the now deserted site is identified as a highly polluted, barren area where the original waste residues from the mine, an ore processing and a smelting site are clearly evident. Previous studies have suggested that high levels of lead and zinc contaminants are still dispersed from this former mine site, both atmospherically and through fluvial transport. For example, high concentrations of Pb, identified by its isotopic signature as originating in Tyndrum, have been found in sediments in Loch Tay, 25 km east of this area. This paper presents the results of a study of the occurrence and magnitude of airborne contamination by dispersion from the former mine site using measurements of metal concentrations in tree bark. These naturally occurring ‘bio monitors＇, which accumulate airborne materials including heavy metals, have become an effective alternative to the more costly air-filter system, which is restricted in scope and coverage. Bark samples were acquired from Scots pine （Pinus sylvestris） trees, which are abundant around the derelict mine site. Suitable locations were chosen to investigate atmospheric transport and deposition of contaminants within the area.     

Strength of ensemble learning in multiclass classification of rockburst intensity

Rockbust is a violent expulsion of rock due to the extreme release of strain energy stored in surrounding rock mass, leading to considerable damages to underground strucures and equipment, and threatening workers' safety. As the operational depth of engineering projects increases, a larger number of factors influence the mechanism of rockburst. Therefore, accurate classification of rockburst intensity cannot be achieved based on conventional criteria. It is urgent to develop new models with high accuracy and ease to implement in practice. This study proposed an ensemble machine learning method by aggregating seven individual classifiers including back propagation neural network, support vector machine, decision tree, k-nearest neighbours, logistic regression, multiple linear regression and Naïve Bayes. In addition, we proposed nine data imputation methods to replace the missing values in the compiled database including 188 rockburst instances. Five-fold cross validation and the beetle antennae search algorithm are used to tune hyperparameters and voting weights of the individual classifiers. The results show that the rockburst classification accuracy obtained by the classifier ensemble has increased by 15.4% compared with the best individual classifier on the test set. The predictor importance obtained by the classifier ensemble shows that the elastic energy index is the most sensitive input variable for rockburst intensity classification. This robust ensemble method can be extended to solve other classification problems in underground engineering projects.     

Impact of episodic herbivory by the tamarisk leaf beetle on leaf litter nitrogen and stem starch content: A short communication

Tamarisk (Tamarix spp.) has in recent decades come to dominate riparian corridors throughout much of the western U.S. The implementation of biological control, utilizing the tamarisk leaf beetle (Diorhabda spp., particularly Diorhabda carinulata), has focused attention and research on this method for Tamarix suppression. Researchers are just beginning to understand how herbivory by Diorhabda affects Tamarix physiology and nutritional dynamics. The purpose of this study was to investigate whether herbivory by D. carinulata altered leaf litter nitrogen and stem starch content, and if so, how such alteration varied across a gradient of herbivory chronosequence. Leaf litter and stem analysis showed significantly higher levels of both nitrogen and stem starch content in trees that had experienced herbivory by the leaf beetle. However, there were no significant differences in nitrogen or stem starch content based on years of beetle herbivory. Higher levels of nitrogen in leaf litter from beetle-affected trees may be a result of herbivory-induced desiccation and foliar mortality prior to the translocation of nitrogen back into plant reserves. Additionally, higher stem starch may be a result of either phloem damage reducing the translocation of photoassimilates, or an increase in the shunting of carbohydrates to the site of new leaf growth. Finally, the lack of correlation between years of herbivory and both leaf litter nitrogen and stem starch may indicate that as of yet there have not been sufficient defoliation events to yield anticipated host plant impact.     

Evapotranspiration and canopy characteristics of two lodgepole pine stands following mountain pine beetle attack

Over the past decade, British Columbia (BC), has experienced the largest mountain pine beetle (MPB) outbreak on record. This study used the eddy‐covariance (EC) technique to examine the impact of the MPB attack on evapotranspiration (E) and associated canopy characteristics of two lodgepole pine stands with secondary structure (trees, saplings and seedlings surviving the attack) located in central BC. MPB‐06, an 85‐year‐old almost pure stand of pine trees, was first attacked in 2006, and by 2010, ~80% of the trees had been killed. MPB‐03, a 110‐year‐old stand with an overstory consisting of over 90% pine and a developed sub‐canopy, was first attacked in 2003 and by 2007 had > 95% pine canopy mortality. EC measurements began in August 2006 at MPB‐06 and in March 2007 at MPB‐03, and continued for four years. Annual total E ranged from 226 mm to 237 mm at MPB‐06, and from 280 to 297 mm at MPB‐03, showing relatively little year‐to‐year change at both sites over the four years. Increased E from the accelerated growth of the surviving vegetation (secondary structure, shrubs and herbs) compensated for reduction in E due to the death of the overstory. Monthly average daytime canopy conductance, the Priestley–Taylor (α), and the canopy–atmosphere decoupling coefficient (Ω) steadily increased during the growing season reaching approximate maximum values of 5 mm s^?1, 0.75 and 0.12, respectively. Potential evapotranspiration was approximated using a vapour pressure deficit‐dependent α obtained at high soil water content. Calculated water deficits indicated some water‐supply limitation to the surviving trees and understory at both sites. Rates of root zone drainage during the growing season were low relative to precipitation. Copyright © 2013 John Wiley & Sons, Ltd.     

Applying broadband spectra to assess biological control of saltcedar in west Texas

Broadband field spectra were assessed to discriminate invasive saltcedar (Tamarix spp.) trees exhibiting feeding damage caused by the saltcedar leaf beetle (Diorhadba spp.) from other land cover types. Data were collected at two study sites near Presidio, Texas in 2010 and 2011. Spectral bands evaluated were coastal blue (400–450?nm), blue (450–510?nm), green (510–580?nm), yellow (585–625?nm), red (630–690?nm), red-edge (705–745?nm), and near-infrared (770–895, 860–1040?nm). Data were evaluated with analysis of variance and Scheffe’s multiple comparison test (α?=?0.05). The red band generally separated severely damaged saltcedar trees from other land cover features. Near-infrared bands separated defoliated saltcedar trees. Broadband spectra has potential for distinguishing saltcedar trees exhibiting feeding damage caused by the saltcedar leaf beetle from other associated features, thus supporting future explorations of airborne and satellite-borne multispectral systems to monitor biological control of saltcedar within complex landscapes.     

Identifying insect infestation hot spots: an approach using conditional spatial randomization

Epidemic populations of mountain pine beetle highlight the need to understand landscape scale spatial patterns of infestation. The observed infestation patterns were explored using a randomization procedure conditioned on the probability of forest risk to beetle attack. Four randomization algorithms reflecting different representations of the data and beetle processes were investigated. Local test statistics computed from raster representations of surfaces of kernel density estimates of infestation intensity were used to identify locations where infestation values were significantly higher than expected by chance (hot spots). The investigation of landscape characteristics associated with hot spots suggests factors that may contribute to high observed infestations.     

皖浙长广地区树皮煤的煤质特征及成因

树皮煤又称乐平煤，以其高挥发分、富氢和高焦油产率且有机显微组分中富含树皮体而被列为我国的特殊煤种之一。从煤岩学和煤化学角度分析了皖浙长广地区树皮煤的煤质特征，讨论了树皮煤的成因，划分出树皮煤的两大成因类型。     

Changes in bark properties and hydrology following prescribed fire in Pinus taeda and Quercus montana

In the eastern United States, the use of prescribed fire as a silvicultural technique to manage for desirable upland tree species is increasing in popularity. Bark physical properties such as thickness, density, and porosity have known associations with fire tolerance among species. These physical properties simultaneously influence rainfall interception and canopy storage and thus are of interest across a range of disciplines. Furthermore, while these characteristics are innate to a species, it is unknown whether repeated exposure to fire facilitates physical change in bark structure and whether these changes are consistent among species. To answer these questions, bark samples were collected from mature pine (Pinus taeda L.) and oak (Quercus montana Willd.) trees from sites across the Bankhead National Forest in Alabama, USA under three different burn regimes: 3-year cycle, 9-year cycle, and no fire. Samples were analysed in the laboratory for bulk density, porosity, water storage capacity, and hygroscopicity (the amount of atmospheric water vapour absorbed by bark during non-rainfall conditions). Drying rates of saturated samples under simulated wetting conditions were also assessed. Oak bark had higher bulk density, lower porosity, and dried slower than pine bark. Interestingly, bark from both species had lower bulk density, higher porosity, greater water storage capacity, and dried faster in stands that were burned every 3 years compared to other fire regimes (p < 0.001). In summary, this study demonstrates that prescribed fire regimes in an eastern US forest alter bark structure and thus influence individual tree control on hydrological processes. The increase in bark water storage capacity, coupled with faster bark evaporation times may lead to less water inputs to the forest floor and drier overall conditions. Further investigation of this fire-bark-water feedback loop is necessary to understand the extent of these mechanisms controlling landscape-scale conditions.     

Employing spatial information technologies to monitor biological control of saltcedar in West Texas

The saltcedar leaf beetle (Diorhadha spp.) has shown promise as a biocontrol agent for saltcedar (Tamarix spp.) invasions in the USA. In Texas, natural resource managers need assistance in monitoring biological control of invasive saltcedars. This study describes application of a medium-format, digital camera acquiring natural colour imagery and global positioning system (GPS) and geographic information system (GIS) technologies to check biological control of saltcedar in west Texas. On 8 July and 8 September 2011, natural colour airborne digital imagery was collected along a 155.8?km transect covering portions of Presidio and Brewster counties of Texas. The camera was tethered to a GPS receiver that geotagged each image and saved the coordinates to a key-hole marked up language file that was viewable on Google Earth. Saltcedar trees exhibiting severe feeding damage and those that were totally defoliated were easily identified in the imagery. The former appeared in orange to brown colour tones; the latter exhibited grey colour tones. Point distribution maps showing locations of saltcedar trees exhibiting feeding damage were developed from GPS information in the GIS. Coordinate points on the map were linked to the corresponding image, permitting the user to have quick access to view imagery. The results of this study show a practical method for monitoring biological control of saltcedar.