The effect of surface fire on tree ring growth of <Emphasis Type="Italic">Pinus radiata</Emphasis> trees

Key message

Pinus radiata trees showed significantly reduced basal area increments and increased latewood/earlywood ratios, when their stem was charred by surface fires even if no needle damage occurred. An interaction of fire damage and precipitation on growth was observed.

Context

Heat from forest fires is able to penetrate beyond the bark layer and damage or completely kill a tree’s cambium. Short-term growth reductions following surface fires have been reported for some species. However, most studies have in common that they describe a compound effect of stem and foliage damage.

Aims

This study investigated the impact of surface fires on the radial growth of Pinus radiata, where only the stem of trees was charred, while no needle damage was recorded.

Methods

Tree ring measurements were performed on cores obtained at breast height. Analysis of variance and tests, based on annual basal area increment values were calculated to quantify pre- and post-fire growth differences of tree ring width and latewood/earlywood ratios.

Results

The analysis revealed significant growth reductions following a surface fire on P. radiata in the year on which the fire occurred as well as in the following year. As a consequence of the fire, basal area increment and latewood/earlywood ratios were significantly reduced. An interaction of fire damage and precipitation on growth was observed.

Conclusion

The obtained results show how fires without crown damage can affect growth and tree ring structure of P. radiata trees and indicate that stem char could be associated with a significant decrease in ring width and latewood/earlywood ratio.

     

The role of indigenous trees for the conservation of biocultural diversity in traditional agroforestry land use systems: The Bungoma case study: In-situ conservation of indigenous tree species

In order to precisely assess the role of agroforestry for the conservation of (agro-)biological diversity there is a need to adjust sampling methods used in plant sociology. This study is on the contribution of agroforestry land use to the in-situ conservation of indigenous trees within a typical East-African smallholder farming system in Western Kenya. A modified approach to measuring species richness and abundance is presented. The selection of tree-rich structures was done according to management patterns rather than considering syntaxonomic classifications from the vegetation science point of view. This approach, which is better suited to the strongly human-influenced vegetation of agroecosystems, employs between-management unit diversity measures to help evaluate abundance and constancy of species in particular management units. The predominant off-farm vegetation patterns are riverine forests, rocky hillsides, hedgerows, wooded grassland relicts, woodlands or colline forest relicts and tree groves whereas the noticeable tree-rich on-farm management units are homegardens, homesteads, life fences, coffee- and banana-groves and annual cropping fields. 98% out of all indigenous tree species known from Bungoma, occur in off-farm lands. 53% of the indigenous tree species occur in tree rich on-farm management units while 47% of the indigenous trees are dependent on the maintenance of off-farm lands. Hedgerows embody the most promising secondary vegetation structure that shows ample potential to accommodate a wide range of indigenous perennial species outside the natural vegetation formations. The pattern of distribution of various vegetation structures, and the mixture with diverse tree-based on-farm plots are interesting features in regard to floristic and eco-diversity on a landscape level. In this respect, three areas that show different population densities and distinct agro-historical conditions were compared. In regions of particular high population density the degree of association of various functional land use forms and woodland structures – each characterised by its own floristic make-up – is comparatively high. In contrast, in regions with less population but that were settled at a later date, one encounters fewer stands of woody plants with lower numbers of species. This revised version was published online in June 2006 with corrections to the Cover Date.     

Hygienic acceptance of wood in food industry

Food is physically manipulated by other materials during production processes, and therefore, food quality and safety are vital in processes where foods are in contact with various materials. Wooden frames were used for centuries for dried egg pasta trays; however, with the development of different materials, wood was slowly abandoned and replaced by plastic. Nevertheless, there are some hygienic considerations concerning plastic frames in the dried egg pasta making industry. In this study, plastic and wooden trays were analysed by swabbing (n?=?210) and evaluated in regard to total number of aerobic counts (TAC), Enterobacteriaceae, Escherichia coli, moulds, yeasts and Staphylococcus aureus using dry medium plates. The aims of the research were to (1) evaluate the total number of microorganisms on wood and plastic material used for pasta trays and (2) make a hygienic evaluation of analysed materials for application in the pasta industry. The research was aimed to answer the question, ‘Does the tray material and/or location of the swab sample influence the colony forming unit (CFU)/20?cm²?’ Results showed a statistical difference in CFU/20?cm² for all bacterial determinations, except for E. coli which was not detected in swabs taken from wooden or plastic trays. This hygiene evaluation study supported the conclusion that the use of wood is appropriate in the food industry from a hygienic and technological point of view.     

Role of Eicosanoids in the Regulation of the Periparturient Period in Cattle

Contents: In this review, the role of eicosanoids in regulation of parturition and the postpartum period was described with special emphasis on the bovine species. The metabolism of arachidonic acid and the production of eicosanoids during the peripartum period was discussed. Prostaglandin E₂ and F_2α (PGE₂, PGF_2α) play an important role in mechanisms controlling parturition. They are involved in luteolysis, uterine contractions and dilation of the cervix. Eicosanoids also seem to influence the loosening processes of the fetal membranes. However, in the literature, conflicting results were found. Many investigations suggested that retained placental membranes could be related to low PGF_2α production and/ or an imbalance of arachidonic acid metabolism in the uterus. The possible role of the lipoxygenase pathway metabolite 15-hydroxy-eicosatetraenoic acid (15-HETE) in expulsion of the fetal membranes was also discussed. As far as the postpartum period is concerned, a relationship between postpartum PGF_2α release and the involution of the uterus was found. Cows with undisturbed uterine involution had higher PGF_2α production than cows with delayed involution. In contrast to the positive effect of PGF_2α on uterine involution, PGE₂ seems to delay the involution processes. Further experiments are necessary in order to study the function of eicosanoids in mechanisms regulating parturition, release of the fetal placental membranes and involution of the uterus.     

The effect of carbon black nanoparticles on some properties of air plasma printed cotton/polyamide 6 fabrics

In this study, cotton/nylon blended fabrics were treated with atmospheric air plasma at various times (30–60 s) and were subsequently printed with pastes containing carbon black nanoparticles. Properties of plasma treated fabrics such as visible-near infrared (Vis-NIR) reflectance, water contact angle, air permeability, and color fastness were measured. It was shown that increasing plasma treatment time decreases reflection level of treated fabrics in Vis-NIR region. Plasma treatment also enhanced the hydrophobicity of cotton/nylon fabrics observed by an increase in water contact angle. Plasma treated samples for 60 s demonstrated lower air permeability than those treated for 30 s. Furthermore, printed samples possessed acceptable levels of fastness against washing, light and crocking.     

Cryptosporidium scrofarum n. sp. (Apicomplexa: Cryptosporidiidae) in domestic pigs (Sus scrofa)

We describe the morphological, biological, and molecular characteristics of Cryptosporidium pig genotype II and propose the species name Cryptosporidium scrofarum n. sp. to reflect its prevalence in adult pigs worldwide. Oocysts of C. scrofarum are morphologically indistinguishable from C. parvum, measuring 4.81–5.96 μm (mean = 5.16) × 4.23–5.29 μm (mean = 4.83) with a length to width ratio of 1.07 ± 0.06 (n = 400). Oocysts of C. scrofarum obtained from a naturally infected pig were infectious for 8-week-old pigs but not 4-week-old pigs. The prepatent period in 8-week-old Cryptosporidium-naive pigs was 4–6 days and the patent period was longer than 30 days. The infection intensity of C. scrofarum in pigs was generally low, in the range 250–4000 oocysts per gram of feces. Infected pigs showed no clinical signs of cryptosporidiosis and no pathology was detected. Cryptosporidium scrofarum was not infectious for adult SCID mice, adult BALB/c mice, Mongolian gerbils (Meriones unguiculatus), southern multimammate mice (Mastomys coucha), yellow-necked mice (Apodemus flavicollis), or guinea pigs (Cavia porcellus). Phylogenetic analyses based on small subunit rRNA, actin, and heat shock protein 70 gene sequences revealed that C. scrofarum is genetically distinct from all known Cryptosporidium species.     

Stabilization of oxidative enzymes in desert soil may limit organic matter accumulation

Phenol oxidase and peroxidase activities in desert grassland soils at the Sevilleta Long Term Ecological Research site in central New Mexico (USA) are far greater than those of temperate soils. Activity is uniformly distributed across particles ranging from >1 mm to <38 μm and is unaffected by autoclaving, in contrast to hydrolase activities. The sorbed enzymes are readily extractable and inactivated by boiling. High soil pH, high stabilized oxidative enzyme activity, and carbonates create optimal conditions for degradation of phenols which increase decomposition potentials and limit soil organic matter accumulation.