Treesearch

Several species of aggressive bark beetle in the genus Dendroctonus (Coleoptera: Curculionidae)undergo large fluctuations in population density with distinct outbreak and non-outbreak phases.We investigated attributes we hypothesized as subject to density-dependent variation (in particular, thoselikely to express phenotypic plasticity) in the southern pine beetle (SPB), Dendroctonus frontalis, as possibleindicators of population fluctuations. These traits were morphology (body size and hindwing shape) andthe sex ratio of trap-captured, dispersing SPB populations. We compared attributes of...

To reduce maladaptation in cultivated seed lots, seed transfer zones (STZs) have been developed for grasslands and other habitats using morphological traits and phenological measurements that only capture the first day of events such as flowering and seed ripening. Phenology is closely linked to plant fitness and may affect genetic loss during harvests of seed raised for ecological restoration. Here, we measured the detailed phenologies of 27 populations from six STZs of bluebunch wheatgrass (Pseudoroegneria spicata) (Pursh) Á. Love (Poaceae) raised in a common garden to test whether...

This Minireview provides a comprehensive discussion on the potential of using acid hydrotropes for sustainably fractionating lignocelluloses for biorefinery applications. Acid hydrotropes are a class of acids that have hydrotrope properties toward lignin, which helps to solubilize lignin in aqueous systems. With the capability of cleaving ether and ester bonds and even lignin-carbohydrate complex (LCC) linkages, these acid hydrotropes can therefore isolate lignin embedded in the plant biomass cell wall and subsequently solubilize the isolated lignin in aqueous systems. Performances of two...

Tree-ring time series provide long-term, annually resolved information on the growth of trees. When sampled in a systematic context, tree-ring data can be scaled to estimate the forest carbon capture and storage of landscapes, biomes, and - ultimately - the globe. A systematic effort to sample tree rings in national forest inventories would yield unprecedented temporal and spatial resolution of forest carbon dynamics and help resolve key scientific uncertainties, which we highlight in terms of evidence for forest greening (enhanced growth) versus browning (reduced growth, increased...

The incorporation of fibers into polymers is a well-known route for realizing composite materials with improved strength, stiffness, and toughness. Cellulose nanofibrils (CNFs) are a promising reinforcement because of their high aspect ratio, high specific stiffness and specific strength, and transparency and the fact that they are derived from renewable and sustainable sources. Here, we demonstrate the application of CNFs for the reinforcement of continuous polymer fibers (filaments) to achieve a concurrent enhancement of strength, stiffness, and fracture toughness. Poly(methyl methacrylat...

To properly evaluate the reliability of lumber structures, good models for the strength distributions of their components are needed. Modulus of rupture (MOR) distributions of structural lumber grades have often been modeled as two-parameter Weibulls. However, in a series of papers, Verrill and others have established that strength properties of visual and machine stress rated grades of lumber are not distributed as two-parameter Weibulls and that modeling them as two-parameter Weibulls can yield large over- or underestimates of probabilities of breakage. Instead, grades of lumber have...

Vacuum drying is an economical alternative to conventional drying for many species under a variety of environmental and economic conditions. Vacuum drying can reduce drying time and be more energy efficient compared with conventional steam drying. But there are many factors to consider when comparing the two technologies. This report describes the principles and practices of vacuum drying and discusses its advantages and disadvantages. Among other concerns, final moisture content variation and residual stress have been significant issues of concern with vacuum drying. Standard vacuum...

The Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins) (Coleoptera: Curculionidae) antiaggregation pheromone, 3-methylcyclohex-2-en-1-one (MCH), has been used since 2000 to protect high-value trees and stands throughout western North America. Operational treatments involve placing individual releasers on a 12m× 12m grid throughout the area to be protected. In this study, six widely spaced trap lines were established with aggregation attractant–baited traps located 1, 3, 9, 27, and 81m from a location where an operational MCH release device was alternately either present or absent, and...

Semiochemical background in the environment can influence insect orientation to release points of the sameor different semiochemicals. endo-Brevicomin is a pheromone component of the tree-killing bark beetleDendroctonus frontalis Zimmermann (Coleoptera: Curculionidae: Scolytinae) that has a biphasic dose–responsecurve, enhancing attraction at low release rates but reducing attraction at high rates. We investigated the effectof artificial manipulation of background levels of endo-brevicomin on D. frontalis responses to sources ofaggregation attractant in the field. Traps baited with the...

The southern pine beetle, Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae: Scolytinae), isamong the most destructive bark beetle pests of pines (Pinaceae) of the southeast and mid-Atlantic UnitedStates of America, Mexico, and Central America. Numerous volatile compounds can stimulate or reduceattraction of the beetle, but efforts to incorporate these into effective, practical technologies for pest managementhave yielded mixed results. Attractants have been incorporated into lures used in monitoringtraps that are employed operationally to forecast outbreaks and detect emerging...