Giant sequoia regeneration in group selection openings in the southern Sierra Nevada

Fire has been linked to the regeneration of giant sequoia (Sequoiadendron giganteum) [Lindley] Buchholz but no studies have directly investigated the effects of opening size and fuel treatment on giant sequoia establishment. Giant sequoia seedling density was analyzed in 36 group selection openings harvested in 1993 at Mountain Home Demonstration State Forest, CA. The experiment consisted of four replicates of a randomized 3 × 3 factorial design which investigated the effects of opening size and fuel treatment on giant sequoia regeneration. Small, medium, and large circular openings had average diameters of 15, 30, and 61 m, respectively. A total of 12 large, 12 medium, and 12 small openings were created. Three fuel treatments were randomly applied to the openings: tractor pile and burn, broadcast burn, and lop and scatter. Analysis of variance (ANOVA) detected no significant differences between treatments and seedling density (p < 0.05). All the treatments had low giant sequoia seedling density regardless of opening size or fuel treatment. Regeneration was completely absent in all openings with the lop and scatter fuel treatment while small openings had low giant sequoia regeneration density regardless of fuel treatment. Giant sequoia seedling density was low because of below average annual and summer precipitation following the creation of the openings and of low seed dispersal. The group selection silvicultural system attempts to simulate the structural complexity of the prehistoric, patchy, high intensity fire regime that once existed in the mixed-conifer forests of the southern Sierra Nevada but important ecosystem processes such as increased seed dispersal following patchy, high intensity fire and large scale nutrient cycling are not duplicated.     

Effects of oral administration of sodium citrate or acetate to pigs on blood parameters, postmortem glycolysis, muscle pH decline, and quality attributes of pork

The objective of this study was to determine the effects of oral administration of sodium citrate (CIT) or acetate (ACE) to pigs on blood parameters, postmortem glycolysis, pH decline, and quality attributes of pork. Previous studies have shown that CIT has the potential to inhibit phosphofructokinase (PFK), a key enzyme in postmortem muscle glycolysis. In Exp. 1, CIT, ACE, or water was orally administered (0.75 g/kg of BW) to 24 pigs. After a 30-min rest, pigs were exercised, and blood samples were taken at 45 and 75 min after oral treatment. Citrate and ACE tended (P = 0.08) to increase blood pH and increased (P = 0.02) bicarbonate levels immediately after exercise. After a 30-min rest, blood pH of pigs administered ACE tended (P = 0.09) to remain higher, whereas blood pH of CIT-treated pigs was similar to that of control pigs. Bicarbonate levels in ACE- and CIT-treated pigs were still greater (P < 0.05) than those of control pigs at 75 min after oral treatment. In Exp. 2, 30 pigs were administered CIT, ACE, or water 45 min before stunning (electric plus captive bolt). Antemortem treatments had no effect (P > 0.10) on muscle pH or postmortem concentrations of the glycolytic metabolites of glucose-6 phosphate, fructose-6 phosphate, fructose-1,6 bisphosphate, glyceraldehyde-3 phosphate, dihydroxyacetone phosphate, or lactate. Minor, but inconsistent, differences in quality attributes were found in LM chops, and no differences in quality attributes were found between control and CIT- or ACE-treated pigs for inside and outside semimembranosus muscles (P > 0.10). There was no significant inhibition of the PFK enzyme by orally administered CIT or ACE; however, the PFK glycolytic metabolite data analysis indicated that PFK was a main regulatory enzyme in postmortem muscle.     

Two mortality events in sea-caged yellowtail kingfish Seriola lalandi Valenciennes, 1833 (Nannopercidae) from Western Australia

In November 2008 a commercial sea-cage operator farming yellowtail kingfish, Seriola lalandi, in Western Australia reported more than 70% mortality of the sea-caged fish. Several parasites and potentially pathogenic bacteria were isolated from the fish, but despite a detailed laboratory investigation the cause of the mortality event was never ascertained. That episode of deaths was followed in January 2009 by a smaller mortality event in fish in a sea cage that had been stocked several weeks earlier. Pathogens similar to those seen in the first mortality event were isolated, but again a single causative agent could not be identified. Multiple stress factors resulting in immunosuppression may have precipitated the mortality events.     

SHORT CONTRIBUTION: Needle-free vaccination in sheep

Multi-dose vaccinators have been in use for many years to vaccinate livestock. A number of needle-free vaccinators that use compressed gas to drive the vaccine through intact skin have been recently introduced to the market. We recently examined the efficacy of a needle-free vaccinator to induce antibodies to tetanus toxoid in sheep. The result indicates that needle-free vaccination can stimulate antibody responses comparable to conventional needle vaccination.     

Spatial patterns of large natural fires in Sierra Nevada wilderness areas

The effects of fire on vegetation vary based on the properties and amount of existing biomass (or fuel) in a forest stand, weather conditions, and topography. Identifying controls over the spatial patterning of fire-induced vegetation change, or fire severity, is critical in understanding fire as a landscape scale process. We use gridded estimates of fire severity, derived from Landsat ETM+ imagery, to identify the biotic and abiotic factors contributing to the observed spatial patterns of fire severity in two large natural fires. Regression tree analysis indicates the importance of weather, topography, and vegetation variables in explaining fire severity patterns between the two fires. Relative humidity explained the highest proportion of total sum of squares throughout the Hoover fire (Yosemite National Park, 2001). The lowest fire severity corresponded with increased relative humidity. For the Williams fire (Sequoia/Kings Canyon National Parks, 2003) dominant vegetation type explains the highest proportion of sum of squares. Dominant vegetation was also important in determining fire severity throughout the Hoover fire. In both fires, forest stands that were dominated by lodgepole pine (Pinus contorta) burned at highest severity, while red fir (Abies magnifica) stands corresponded with the lowest fire severities. There was evidence in both fires that lower wind speed corresponded with higher fire severity, although the highest fire severity in the Williams fire occurred during increased wind speed. Additionally, in the vegetation types that were associated with lower severity, burn severity was lowest when the time since last fire was fewer than 11 and 17 years for the Williams and Hoover fires, respectively. Based on the factors and patterns identified, managers can anticipate the effects of management ignited and naturally ignited fires at the forest stand and the landscape levels.