Legacies of organic matter removal: decreased microbial biomass nitrogen and net N mineralization in New Zealand Pinus radiata plantations

The effect of variations in organic matter removal during harvesting on microbial biomass nitrogen was determined in four Pinus radiata plantations between 9 and 17 years after harvesting. Variation in microbial biomass nitrogen with season and the response of net nitrogen mineralization to organic matter removal after 9 and 17 years were also determined at two of the sites. The microbial biomass nitrogen in the fermentation-humus (FH) layer was correlated with litter fall characteristics and did not vary with organic matter removal, but the total mass of microbial biomass nitrogen in the FH layer was significantly reduced by increased organic matter removal. The microbial biomass nitrogen in the mineral soil was decreased by increased organic matter removal and was strongly correlated with moisture content and total nitrogen concentration. The FH layer microbial biomass nitrogen did not vary with season, but mineral soil microbial biomass nitrogen varied with season at one site, probably due to increased moisture availability. Net nitrogen mineralization in the mineral soil, determined by an anaerobic incubation, was decreased by increased organic matter removal and was strongly correlated with microbial biomass nitrogen. The persistence of the significant differences in microbial biomass nitrogen and net nitrogen mineralization indicated that variations in organic matter removal during harvesting have long-term effects on soil microbial properties and activity during the life of the subsequent rotation. This has implications for the selection of harvesting techniques to promote the maintenance of site productivity and to minimise disruption to the soil biota.     

Avian conservation priorities in a top-ranked biodiversity hotspot

Rio de Janeiro state in Brazil has one of the most diverse and most endangered avifaunas in the continental Americas. Many of these endangered birds are endemic to the Atlantic Forest biodiversity hotspot, and some even endemic to Rio de Janeiro itself. As with all other forested hotspots, little original forest remains. Much of that is outside formal protected areas and faces the risk of deforestation. These factors create special circumstances for setting conservation priorities — ones common to hotspots in general — but typically not to many conservation priority setting exercises.We mapped the distribution of the remaining habitat for the 189 birds in Rio de Janeiro state that are officially endangered and/or endemic to the Atlantic Forest. Using those habitat maps, we calculated the amount of habitat currently within protected areas for each species. We then prioritized all non-protected parts of the state for their avian conservation value and their potential contribution to a comprehensive protected area system. This analysis identified 10% of the remaining unprotected part of the state as the highest priority for avian conservation. We further highlight specific locations where conservation actions could create a more comprehensive protected area system for the avifauna of Rio de Janeiro state.     

Endogenous Ethane and Ethylene Of Poa pratensis Leaf Blades and Leaf Chlorosis in Response to Biologically Active Products of Bipolaris sorokiniana

Infection of Poa pratensis leaf blades and callus tissue by Bipolaris sorokiniana increases the production of ethylene and ethane. The ethylene is responsible for most of the chlorosis that occurs during pathogenesis. The nonselective toxin(s) produced by B. sorokiniana is known to disrupt membranes and to damage chlorophyll, but it is not known whether it can induce an increase in ethylene or ethane. Research was initiated to determine the effect of a biologically-active extract of B. sorokiniana on the endogenous ethylene and ethane of intact P. pratensis leaf blades and on subsequent development of chlorosis. The extract did not increase endogenous ethylene of treated leaves, but it was associated with an increase in endogenous ethane between 24 and 96h after treatment. Chlorophyll loss occurred 96h after treatment and persisted for the duration of the study (168h). The chlorophyll content of treated leaf blades ranged from 72% to 80% of control leaf blades. The observations suggest that the extract of B. sorokiniana can induce chlorophyll loss from treated leaf blades independent of an increase in endogenous ethylene by directly damaging chloroplasts with a concurrent release of ethane. The ethane is believed to be a by-product of pathogenesis.     

Relationship of vitamin E supplementation and antimicrobial treatment with acute-phase protein responses in cattle affected by naturally acquired respiratory tract disease

OBJECTIVE: To correlate serum concentrations of fibrinogen (Fib), haptoglobin (Hap), serum amyloid-A (SAA), and alpha-1 acid glycoprotein (AGP) with clinical respiratory tract disease and response to treatment in transport-stressed feedlot cattle fed vitamin E-supplemented diets. ANIMALS: 387 heifer calves (mean initial weight, 197 kg). PROCEDURE: Calves purchased from an order buyer were delivered to a feedlot to study the effects of dietary supplementation with 2,000 IU of vitamin E for 0, 7, 14, or 28 days after arrival. Serum or plasma Fib, Hap, SAA, and AGP concentrations were measured on days 0, 7, and 28 after arrival as well as at the time of treatment for respiratory tract disease with antimicrobial drugs and after completion of treatment. RESULTS: Vitamin E supplementation was associated with decreased treatment costs. In cattle that were not recognized as sick or responded positively to 1 antimicrobial treatment, serum Hap concentrations were significantly lower on days 0 and 7 than concentrations for cattle that required > 1 treatment. Serum Hap concentrations and ratios of Hap to SAA on day 0 significantly correlated with the number of antimicrobial treatments required. Serum Hap concentrations at the time of initial treatment were significantly lower for cattle that required only 1 treatment, compared with those that required > 1 treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Serum Hap concentrations are of potential value for use in assessing feedlot cattle that may become ill as a result of respiratory tract disease and for use in monitoring treatment efficacy.     

Evaluating the upper thermal limits of glochidia for selected freshwater mussel species (Bivalvia: Unionidae) in central and east Texas,and the implications for their conservation

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Qualitative risk assessment of transmission pathways of highly pathogenic avian influenza (HPAI) virus at live poultry markets in Dhaka city,Bangladesh

Analysis of environmental samples obtained from the Live Poultry Markets (LPMs) of Dhaka City, Bangladesh, has revealed that the highest degree of prevalence of highly pathogenic avian influenza A (HPAI, H5N1), besides other subtypes of the LPAI virus, poses the plausible risk of transmission of these viruses between human and poultry species. The present study was conducted using the OIE risk analysis framework to assess the risk level of each pathway successively. The estimated risk parameters were integrated towards to obtain the overall risk level for each specific HPAI transmission pathway using the matrix adapted by Cristobel Zepeda accompanying other expert consultations. The relevant data obtained from published and unpublished sources, together with survey data of field observations, were used to formulate and confirm the risk pathways and their associated risks. The results revealed that the risk of the release of the HPAI virus was medium when exposure was high. Additionally, the consequence would be considered very high with a medium degree of uncertainty for all parameters. Ultimately, the overall risk for transmission was estimated as medium with a medium degree of uncertainty. The findings of this study reveal that there is a significant threat that HPAI virus transmission could occur among poultry and humans and effectively sustain within the environment of the LPMs. Our findings are primarily focused on public health considerations, the hygienic slaughter of poultry and the relevant cleaning and sanitation practices conducted in the LPMs to support evidence‐based decision‐making processes. The findings of the study have the potential to be used to formulate effective risk reduction measures and can be further adapted in low‐resource settings without major infrastructural changes required of the LPMs. All of which would reduce the risk of HPAI virus release and further lessen the degree of exposure and transmission in established LPMs.     

Impacts of plantation forest management on soil organic matter quality

Purpose  

Light fraction soil organic matter is characterized by rapid mineralization due to the labile nature of its chemical constituents and to the lack of protection by soil colloids. The changes in the size of light fraction soil organic matter constituents are useful early indicators of management-related carbon (C) and nutrient changes. However, previous studies have not assessed the impacts of forest management practices on the chemical composition and sources of organic matter in the light fraction. The change in the chemistry of light fraction soil organic matter may significantly affect turnover rate of organic matter in the whole soil and soil fertility. The aim of this study was to assess how different forest management practices would affect the chemical composition of light fraction soil organic matter.