Global forest systems: An uncertain response to atmospheric pollutants and global climate change?

Forest systems cover more than 4.1×10⁹ ha of the Earth's land area. The future response and feedbacks of forest systems to atmospheric pollutants and projected climate change may be significant. Boreal, temperate and tropical forest systems play a prominent role in carbon (C), nitrogen (N) and sulfur (S) biogeochemical cycles at regional and global scales. The timing and magnitude of future changes in forest systems will depend on environmental factors such as a changing global climate, an accumulation of CO₂ in the atmosphere, and increase global mineralization of nutrients such as N and S. The interactive effects of all these factors on the world's forest regions are complex and not intuitively obvious and are likely to differ among geographic regions. Although the potential effects of some atmospheric pollutants on forest systems have been observed or simulated, large uncertainty exists in our ability to project future forest distribution, composition and productivity under transient or nontransient global climate change scenarios. The potential to manage and adapt forests to future global environmental conditions varies widely among nations. Mitigation practices, such as liming or fertilization to ameliorate excess NO_x or SO_x or forest management to sequester CO₂ are now being applied in selected nations worldwide.The U.S. Government's right to a non-exclusive, royalty free licence in and to any copyright is acknowledged.     

Emission Inventories for SO2 and NOx in Developing Country Regions in 1995 with Projected Emissions for 2025 According to Two Scenarios

Water, Air, &; Soil Pollution - Top-down inventories of anthropogenic SO2 and NOx emissions were compiled for 1995 for developing country regions. Regional emission factors were used to generate...     

Trends in Dissolved Gaseous Mercury in the Tahquamenon River Watershed and Nearshore Waters of Whitefish Bay in the Michigan Upper Peninsula

A field study was conducted in June of 1998 to characterize the dynamics of dissolved gaseous mercury (DGM) in the TahquamenonRiver watershed and nearshore waters of Whitefish Bay in the Upper Michigan Peninsula. We found that over a transect acrossthe watershed, DGM levels increased generally from a creek (mean = ～12 pg L^-1), passing through the watershed, to the nearshore surface waters of the bay (mean = ～29 pg L^-1). DGM levels in nearshore surface waters of the bayranged from ～15 to ～50 pg L^-1 and peaked generally around noontime, exhibiting diurnal trends. A significant DGM decline from ～32 pg L^-1 in the early morning to ～15 pg L^-1 during the day was observed in these surface waters following passage of a coldfront, probably caused by wind-induced mixing and decrease insolar radiation associated with the frontal passage.     

The potential acidity associated with dews,frosts, and fogs

Acidity associated with special meteorological events such as dews, frosts, and fogs may cause significant environmental effects ranging from increased leaching of plant metabolites to material corrosion. In addition, dews, frosts and fogs occur with much greater frequencies than rain or snow in most areas. Due to these facts, a theoretical study was conducted to determine the potential acidity associated with these events. Results from this study showed the potential acidity associated with these events to be significant. Values of fog pH are extremely sparse, but indicate that they are slightly acidic. However, these experiments have probably under-estimated the actual acidic potential of dew and frost. Theoretical calculations indicate that synergistic acidity from dew or frost in combination with dry deposition may result in very strong localized acidities.     

Effects of feeding diets containing low crude protein and coarse wheat bran as alternatives to zinc oxide in nursery pig diets

Two experiments were conducted to determine the effects of crude protein (CP) level in diets containing coarse wheat bran (CWB) with or without pharmacological levels of Zn (provided by zinc oxide: ZnO) on growth performance and fecal DM of nursery pigs. In experiment 1, 360 barrows (Line 200 × 400, DNA, Columbus, NE, initially 5.6 kg) were allotted to 1 of 6 dietary treatments from d 0 to 21 after weaning with 5 pigs per pen and 12 pens per treatment. Treatments included a positive control diet (21% CP) with 3,000 mg/kg Zn in phase 1 and 2,000 mg/kg in phase 2; negative control (21% CP) with 110 mg/kg added Zn, and 4 diets containing 4% CWB and 110 mg/kg added Zn formulated to contain 21%, 19.5%, 18%, or 16.5% CP. The 2 control diets and 21% CP CWB diet contained 1.40% standardized ileal digestible (SID) Lys in phase 1 and 1.35% SID Lys in phase 2, while the 19.5%, 18%, and 16.5% CP diets contained 1.33, 1.25 and 1.20% Lys, respectively, in both phases. Pigs fed the positive control diet containing pharmacological ZnO had increased (P < 0.05) ADG and G:F compared with the negative control and the 21% CP CWB diet. Reducing CP (concurrently with SID Lys) in diets containing CWB decreased ADG and G:F (linear, P = 0.002); however, fecal DM increased (linear, P = 0.005). In experiment 2, two groups of 300 and 350 pigs, initially 7.0 and 6.2 kg, respectively, were used with 5 pigs per pen and 26 pens per treatment. The objective was to determine if adding back essential AA would improve growth performance of pigs fed the low CP diets. All dietary treatments were fed for 13 days, contained 4% CWB, and consisted of: (1) positive control with 2,000 mg/kg of Zn and 21% CP (1.35% SID Lys); (2) no ZnO and 21% CP; and 3 diets with no ZnO formulated to 18% CP and (3) 1.2% SID Lys; (4) 1.35% SID Lys by the addition of feed grade amino acids (AA), and (5) diet 4 with non-essential amino acids (NEAA; Gly and Glu). Pigs fed 21% CP with ZnO had increased (P = 0.001) ADG compared to those fed 18% CP (1.35% SID Lys) with high levels of feed grade amino acids or those fed the reduced SID Lys (1.2%) diet. Overall, G:F was improved (P < 0.001) for pigs fed 21% CP diets and those fed the 18% CP diet with NEAA compared to pigs fed 1.2% SID Lys and pigs fed high levels of feed grade amino acids. Fecal DM was increased for pigs fed the reduced SID Lys diet. In summary, pharmacological levels of Zn improve pig growth performance, but reducing CP (and subsequently SID Lys) decreased nursery pig growth performance.     

Potential for Asexual Propagation of Several Commercially Important Species of Tropical Sea Cucumber (Echinodermata)

Six species of tropical sea cucumbers (Echinodermata) of high to moderate commercial value were evaluated as to their potential for being propagated asexually by induction of transverse fission. The species considered were Thelenota ananas, Holothuria fuscogilva, Actinopyga mauritiana, A. miliaris, Stichopus chloronotus , and S. variegatus . Rubber bands placed midbody on the sea cncumbers provided an effective yet simple technique to induce transverse fission. Although fission could be induced in all six species, only T. ananas and S. chloronotus had the ability to regenerate both anterior and posterior parts into whole animals. Other species showed no or low potential for regeneration ( H. fuscogilva, A. mauritiana ) or regeneration of only the posterior part into whole animals ( S. variegatus, A. miliaris ). Both T. ananas and S. chloronotus had survivorship of nearly 80% or greater. S. chloronotus regenerated anterior and posterior parts into whole animals within 3 mo. In contrast, T. ananas regenerated the posterior part into a whole animal within 5 mo while the anterior part was regenerated within 7 mo. Consequently, weight recovery began earlier with S. chloronotus relative to T. ananas .     

Oral Lesions Associated with Orotracheal Administered Mechanical Ventilation in Critically III Dogs

The incidence and clinical progression of oral lesions in a cohort of critically ill patients administered mechanical ventilation via orotracheal intubation were observed prospectively in the Intensive Care Unit (ICU) of the University of California, Davis Veterinary Medical Teaching Hospital. Oral cavities of these patients were examined within 24 hours of being placed on the ventilator and at least daily thereafter during ventilator therapy. As part of the study protocol, any lesion noted was treated. Twenty-one critically ill canine patients (median age of 7 yrs; range <1 to 19 yrs) were observed from 1 January 1995 through 31 August 1995. Over ninety percent (90.5%) of the observed patients developed oral lesions subsequent to being mechanically ventilated. Erosive and ulcerative mucosal lesions were the most frequently observed (15/43) with the tongue being the most frequently involved oral structure. Most of the observed soft tissue oral lesions appeared secondary to persistently applied pressure from teeth, mouth gags, endotracheal tubes, and other monitoring devices. Efforts taken to prevent persistently applied trauma, such as periodic positional changes of equipment and padding of susceptible structures, apeared effective in preventing oral lesions. There were indications of gastric reflux in 6 patients (28.6%), as evidenced by secretions in the oral cavity with a pH of <6 and containing digested blood. Ulcerative lesions in the subset of patients with gastric reflux seemed to worsen in severity with exposure to the low pH secretions. Over the course of the study, the ICU nursing staff developed an effective protocol for the care of the oral cavity: treating mucosal erosions and ulcers topically8 with a dilute chlorhexidine solution (0.05%), removing oral secretions via suction as needed, and padding persistently traumatized tissues with glycerin moistened gauze. Oral lesions in orotrachealy intubated and mechanically ventilated patients are predictable, preventable, and treatable. Most lesions are pressure induced, associated with monitoring/therapeutic equipment, and appear to be preventable with appropriate nursing protocls. Most observed oral lesions clinically improved with routine, periodic dilute chlorhexidine rinses and relief of applied pressure.     

High-Frequency Jet Ventilation in Anesthetized, Paralyzed Dogs and Cats Via Transtracheal and and Endotracheal Tube Routes

The ability of the SAV 6 high-frequency jet ventilator to effectively ventilate three anesthetized, paralyzed cats (3.2–4.2 kg), two small dogs (7.2 and 10.0 kg), six medium-sized dogs (20.5–25.0 kg), and three large dogs (36.0–43.0 kg) via a 14-gauge (dogs) or a 16-gauge (cats) catheter placed percutaneously into the trachea via the cricothyroid membrane or into a preplaced endotracheal tube was evaluated. The lowest driving pressure within the range of 0.25 to 2.0 kg/cm² (1 kg/cm²= 14.2 psi) and the highest cycle rate within the range of 60 to 240 per minute that would generate a PaCO₂ of 30 ± 3 mm Hg were determined.
All animals could be ventilated to a PaC0₂ of 30 ± 3 mm Hg by the endotracheal tube and transtracheal route, except the largest dogs, which couid be ventilated to an average PaC0₂ of 36 mm Hg by the transtracheal route. The transtracheal route consistently required higher driving pressures and lower cycle rates than did the endotracheal tube route. Cats could be ventilated with a driving pressure of 0.25 kg/cm²; small dogs could be ventilated with 0.5 to 1.0 kg/cm₂; medium-sized dogs with 1.0 to 1.5 kg/cm²; and large dogs with 1.5 to 2.0 kg/cm².
The SAV 6 high-frequency jet ventilator can effectively ventilate cats and dogs (7.2–43.0 kg) via a transtracheal catheter and an endotracheal tube.