Modeling production and decay of coarse woody debris in loblolly pine plantations

Forest management can have large impacts on the production and yield of coarse woody debris (CWD) in terrestrial ecosystems, yet few modeling tools exist to inform such efforts. The goal here was to develop a set of prediction equations for use in conjunction with loblolly pine (Pinus taeda L.) modeling and inventory systems to estimate CWD yields at scales ranging from individual trees to whole plantations. Permanent field plots from a 21-year study of thinning effects on plantation growth and yield across the commercial range of the species in the southern United States were surveyed to obtain sample data on CWD volume, density, and mass. Measured CWD properties were combined with inventory records of tree mortality over the study duration to characterize CWD production, decay and yield in a series of prediction equations. The resulting equations predict CWD attributes of dead trees including dry weight (kg) and fraction of standing versus downed woody material based on the time since death (years), tree diameter at breast height (cm) and height (m) at time of death and geographic coordinates of latitude and longitude. A stand-level equation predicts total CWD yield (Mg ha⁻¹) for thinned or unthinned stands based on plantation age, stem density (trees ha⁻¹), and the average height of dominant and codominant trees (m). Piece-level equations predict dry density (kg m⁻³) or nitrogen concentration (%) of CWD pieces based on their position (standing or down), ordinal decay classes, and latitude. The tree and stand-level prediction equations are designed for use in GIS or growth and yield modeling systems. The piece-level equations are designed to be used in inventory applications that survey CWD. The equations should facilitate the accurate and facile determination of mass, carbon, and nitrogen contents of CWD in planted loblolly pine forests of the southern United States.     

Post-wildfire seeding in forests of the western United States: An evidence-based review

Broadcast seeding is one of the most widely used post-wildfire emergency response treatments intended to reduce soil erosion, increase vegetative ground cover, and minimize establishment and spread of non-native plant species. We conducted an evidence-based review to examine the effectiveness and effects of post-wildfire seeding treatments on soil stabilization, non-native species invasion, and plant community recovery in the western U.S. We reviewed 94 scientific papers and agency monitoring reports identified using a systematic search protocol. As sampling designs have become more rigorous in recent years, evidence that seeding is effective in reducing erosion has decreased. Of highest and high quality studies evaluating soil erosion, 92% (11 of 12) were published since 2000, none of which showed an effective result. Before 2000, the majority of the studies (71%) fell into the lowest quality categories, of which 72% showed seeding to be effective. The majority of studies (20 of 27, 74%) evaluating soil erosion in seeded versus unseeded controls showed that seeding did not reduce erosion relative to unseeded controls. Even when seeding significantly increased vegetative cover, seeded sites rarely supported plant cover levels considered sufficient to stabilize soils within the first and second year post-wildfire. Of the 11 studies evaluating seeding effectiveness for curtailing invasions of non-native plant species, an almost equal percentage found seeding treatments to be either effective (54%, 6 studies) or ineffective (45%, 5 studies). However, the majority of effective and ineffective treatments (83% and 80%, respectively) used non-native species. Sixteen of 26 studies (62%) evaluating seeding effects on plant communities reported that seeding suppressed recovery of native plants, although data on long-term impacts of this reduction are limited. The literature suggests that post-wildfire seeding does little to protect soil in the short-term, has equivocal effect on invasion of non-native species, and can have negative effects on native vegetation recovery, although long-term studies are needed to assess lasting impacts of seeded species.     

“Our market is our community”: women farmers and civic agriculture in Pennsylvania,USA

Civic agriculture is characterized in the literature as complementary and embedded social and economic strategies that provide economic benefits to farmers at the same time that they ostensibly provide socio-environmental benefits to the community. This paper presents some ways in which women farmers practice civic agriculture. The data come from in-depth interviews with women practicing agriculture in Pennsylvania. Some of the strategies women farmers use to make a living from the farm have little to do with food or agricultural products, but all are a product of the process of providing a living for farmers while meeting a social need in the community. Most of the women in our study also connect their business practices to their gender identity in rural and agricultural communities, and redefine successful farming in opposition to traditional views of economic rationality.     

Carotenodermia in a Horse

This case report describes an 11-year-old Appaloosa gelding that was examined because of yellow–orange tinting of the skin of the muzzle, eyelids, sheath, anus, and perianal region without discoloration of the sclera or mucus membranes. The horse was reported to preferentially eat dandelions which were plentiful in the pasture. Physical examination was normal, except for the discolored skin. A serum chemistry panel was normal. Carotenodermia was suspected. Serum carotenoid concentrations were higher in the affected horse as compared with concentrations in two horses with depigmented skin of normal color that were on grass pasture in the same geographic area. The horse remained systemically healthy and the abnormal skin color had almost disappeared when he was examined 7 weeks later. Carotenodermia can occur in horses and can be differentiated from jaundice because the sclera remains unaffected. Veterinarians should be aware that the condition is benign and spontaneously resolves after stopping carotenoid intake.     

Where to shoot your pilodyn: within tree variation in basic density in plantation Eucalyptus globulus and E. nitens in Tasmania

Longitudinal patterns of within tree variation for basic density were determined for plantation Eucalyptus globulus (ages 5 and 10 years) and E. nitens (ages 5, 10 and 15 years) growing in three geographic areas in Tasmania. Each tree was sampled by taking discs from a combination of percentage heights (0, 10, 20 ___ 70%) and fixed height samples (0.5 m, 0.7 m ___ 1.5 m). At each of the fixed heights, a single pilodyn reading was taken from each of 4 aspects. Weighted whole tree density was calculated from the percentage height samples and used for correlation and regression analysis with the fixed height samples. Both species showed an initial drop in density between the felling cut (zero height) and 0.5 m, followed by a linear increase in density between 10% and 70% of tree height. Slope of fitted regressions were parallel within species but differed significantly between the species (1.14 kg/m³ and 1.62 kg/m³ per 1% increase in height above 10% for E. globulus and E. nitens, respectively). Density at all fixed heights was highly correlated with whole tree values for E. globulus, but results were variable across sites for E. nitens. Both species were found to contain trees which produced aberrant pilodyn readings. For E. globulus, the optimal sampling height was 1.3 m above ground and the mean pilodyn reading was found to predict whole tree density with an accuracy of ±21 kg/m³. For E. nitens, optimal sampling height was 1.5 m above ground. However, pilodyn readings around the stem were not very repeatable and correlations with whole tree density were lower, resulting in the accuracy of prediction of whole tree density being ±26 kg/m³.     

Detection and spread of Phytophthora austrocedri within infected Juniperus communis woodland and diversity of co‐associated Phytophthoras as revealed by metabarcoding

Phytophthora austrocedri is a recently invasive soilborne pathogen which is causing widespread mortality of Juniperus communis in northern Britain. The pathways by which a single genotype of P. austrocedri has spread to infect such a geographically dispersed range of woodland sites within a relatively short timeframe are unknown. This study examined the detectability of P. austrocedri in soil and water within infected J. communis woodland using qPCR to gain a better understanding of the pathogen's key mechanisms of spread. A Phytophthora metabarcoding method was also applied to investigate the wider diversity of Phytophthora species present in water at one of the sites. qPCR analyses of P. austrocedri in soil samples at a J. communis woodland exhibiting low‐to‐moderate levels of disease suggested a slow natural spread of the pathogen in soil, requiring high moisture conditions. However, the ubiquity of P. austrocedri DNA in soil samples collected across a heavily infected J. communis site suggests that once established at a site the pathogen can be spread readily in soil locally, most likely vectored by animal movements and/or human activities. The hypothesis that P. austrocedri is aerially transmitted in rainwater was not adequately proven, and an alternative hypothesis for the widespread distribution of the pathogen on J. communis in northern Britain is presented. Metabarcoding identified DNA from a diverse range of Phytophthora species in river and rainwater samples although the main target pathogen, P. austrocedri, was not amplified which disagreed with some of the qPCR findings. Possible reasons for this are discussed.     

Heathland management in Surrey,England

Heathland in Surrey, England, is managed primarily for purposes of amenity and wildlife conservation. Many of the ecological problems associated with the management of the open heath areas stem from frequent, accidental fires and from the absence of grazing. This study discusses the causes and consequences of these problems for heathland managers.     

Fungicidal activity of substituted quinoxalines

Twenty substituted quinoxalines based on the structure of 6 (or 7)-methyl-3-phenyl-1, 2-dihydroquinoxalin-2-one, a fungicidally active photodegradation product of quinomethionate, were synthesised. Eleven of these compounds had ED₅₀ values, as protectant sprays against Podosphaera leucotricha, of 0.1 mmol or less; these compounds had an aromatic substituent at the 3-position of the quinoxaline ring. They were less active as protectant leaf dips against Erysiphe graminis f. sp. hordei than against Podosphaera leucotricha; none showed any systemic activity as a soil-applied treatment against Podosphaera leucotricha. One compound was more active than quinomethionate as an eradicant spray. In spore germination tests on fungi from different taxonomic groups, the quinoxaline derivatives were active against only one basidiomycete (Uromyces fabae), whereas quinomethionate showed a broad spectrum of activity. The possible significance of this difference in spectrum of activity with respect to the mode of action is discussed.