Does prescribed burning mean a threat to the rare satyrine butterfly Hipparchia fagi? Larval-habitat preferences give the answer

The ecological effects of fire management, especially regarding arthropods are poorly investigated. Burning in winter was assumed to pose a threat to butterfly species hibernating as larvae. To assess the impact of prescribed burning on population viability, we analysed larval-habitat preferences of the highly endangered, xero-thermophilous butterfly Hipparchia fagi in vineyards of the Kaiserstuhl region (southern Germany). Microhabitat preference analyses for mature larvae and egg-laying females revealed a preference of H. fagi for Bromus erectus-dominated communities with sparse vegetation coverage and a distinct tuft growth of the host plant B. erectus on microclimatically benefited slopes. We explain the preference of B. erectus by a preference of vegetation structure. The grass tufts offer a suitable climatically buffered living space for larvae. Egg deposition took place on dry substrate at positions of high solar radiation, thus adapted to hot and dry microclimate. As the larval habitat was sparsely vegetated as well as generally legally protected, fire management was not applicable and therefore not affecting the populations. We think it is conceivable that H. fagi, occurring here at its northern range limit, might expand its larval habitat into denser, combustible B. erectus stands in the course of global warming. A change in habitat preferences would necessitate a re-evaluation of management options.     

Salt tolerance of rice cultivars

Summary The dry matter production and the concentration of nutrients in rice (Oryza sativa L.) cultivars from soil adjusted to different levels of salinity were evaluated under a greenhouse conditions. Soil salinity levels were produced by applying 0.34 mol l^–1 solution of NaCl which resulted in the following levels, control (0.29), 5, 10 and 15 dS m^–1 conductivity of saturation extract. The effect of salinity on dry matter production varied from cultivar to cultivar.The concentrations of P and K in the tops of rice cultivars decreased with increasing soil salinity. But the concentrations of Na, Zn, Cu and Mn increased.Significant varietal differences were found in relation to salinity tolerance. Based on dry matter yield reduction, rice cultivars were classified as tolerant, moderately tolerant, moderately susceptible or susceptible.     

PHOTOADAPTATION,GROWTH AND PRODUCTION OF BOTTOM ICE ALGAE IN THE ANTARCTIC1

Biomass, chemical composition, growth rates and the photosynthetic response of natural populations of sea ice algae in McMurdo Sound, Antarctica were followed over most of the spring bloom to examine temporal variability under a relatively constant incident irradiance (ca. 1500–1700 μE · m^-2· s^-1 at solar noon). Collection were restricted to bottom 20 cm of the ice sheet in an area with little or no snow (0–5 cm). At low temperature and irradiance these algae normally exhibited low assimilation numbers (ca. 0.1–0.4 mg C · mg Chl^-1· h^-1). Average growth rates (0.02–0.45 d^-1), based on changes in standing stocks, were also low. Biomass, biochemical composition, growth rates, assimilation numbers and photosynthetic efficiencies (mg C · mg Chl^-1· h^-1 (μE · m^-2· s^-1)^-1) displayed large fluctuations over periods of several days during the growth season. On the other hand, I_k which is an index of photoadaptation, and I_m, the optimal irradiance for photosynthesis, were relatively constant with less than twofold variation throughout our study. Substantial nutrient fluxes (3.3–8.0 mmol Si or N · m^-2· d^-1) were necessary to satisfy the minimum nutrient demand for the observed biomass levels and population growth rates; over the 41 days of our study, integrated nutrient demand represented 69–150 mmol N or Si · m^-2, Only 5–25% of this total demand could be met by all of the nutrients in the ice sheet, if they were readily available. However, adequate amounts were present in the top few meters of the water column. With small nutrient gradients in surface waters below the sea ice, vertical eddy diffusivities on the order of 3.8–9.3 cm²· s^- should supply sufficient nutrients to meet algal demand.     

Extending the limits of Bacillus for novel biotechnological applications

Bacillus, generally regarded as safe, has emerged as a robust organism that can withstand adverse environmental conditions and grows easily to very high densities. Bacillus has been recognized for its biotechnological applications on an industrial scale. Recent efforts have shown the potential of Bacillus to generate biofuels (hydrogen), biopolymers (polyhydroxyalkanoates), and bioactive molecules (acyl-homoserine lactonases). Bacillus can be considered the dark horse in the race to generate sustainable energy, ecofriendly non-fossil fuel-based polymers, and bioactive molecules for use as therapeutics.     

Early growth invigoration of jack pine seedlings by natural plant growth regulators

 Survival of conifer transplants is often poor on exposed planting sites in the boreal forest. More than one-third of all conifers do not become established. To enhance the competitive ability of jack pine seedlings, seeds were treated with natural plant growth regulators (PGRs; viz., homobrassinolide, salicylic acid, and two polyamines, spermine and spermidine) and growth promotion was studied for 16 days. Homobrassinolide (5 ng l^–1), salicylic acid (100 μg l^–1) and spermine (10 μg l^–1) enhanced elongation growth and elongation rate of whole plant. Homobrassinolide (5 ng l^–1) and salicylic acid (100 μg l^–1) stimulated root elongation by 38% and 10% respectively while spermine (1000 μg l^–1) increased needle growth by 14%. Homobrassinolide stimulated dry weight growth and growth rate. Homobrassinolide recorded over 20% increase in dry matter production, apportioned equally to root and needles, whereas spermine enhanced total dry matter production by almost 10%, mostly by increasing needle weight. Homobrassinolide facilitated nearly 19% increase in growth rate while spermine recorded only a 7% growth promotion. Spermidine inhibited both elongation and dry weight growth at all concentrations. Growth promotion by homobrassinolide, salicylic acid and spermine may be through an acceleration of processes connected to cell elongation, cell division and C allocation and these PGRs showed most promise for the early invigoration and improvement of jack pine seedling growth. Received: 27 August 1997 / Accepted: 8 January 1998     

Assessment of post extraction complications in Indians

Extraction is one of the commonest procedures in dentistry. Therefore, it is of interest to evaluate the post extraction complications in patients undergoing extractions of permanent teeth. A total of 70 adult patients who had undergone dental extractions and presented with post -operative complications were included in the study and evaluated. Data collected was statistically analyzed using SPSS software and results obtained. Most of the patients with post extraction complications were in the age group of 31-40 years (21.6%), followed by 21-30 (20.2%) and 61-70 years (20.2%). Dry socket (39.19%) was the common post extraction complication in our study especially in the age group of 31-40 years. There was a statistically significant association between age of the patients and the post extraction complications (p<0.001). In our study, post extraction complications were commonly observed in age group of 31-40 years with a predilection for males. Dry socket was the most common post extraction complication. Age of the patient has a significant effect on post extraction complications. However, gender, smoking habits and systemic diseases have no influence on post extraction complications.     

A revision of the Verticillium fungicola species complex and its affinity with the genus Lecanicillium

Verticillium fungicola, the type species of Verticillium sect. Albo-erecta, and related taxa were studied using morphological and molecular techniques. Sequences of the ITS region and SSU rDNA suggest that V. fungicola is very close to members of the genus Lecanicillium and unrelated to other species that were originally accommodated in the same section. New combinations in Lecanicillium are proposed for Verticillium fungicola and its var. flavidum at species rank, L. f. var. aleophilum is retained as a variety. These taxa can be distinguished from each other by optimum and maximum temperatures for growth, in addition to ITS sequence differences. Morphologically, L. flavidum is also distinct by repeated branching of the conidiophores, whereas the two varieties of L. fungicola have a simple conidiophore axis.     

Restoring riparian meadows currently dominated by Artemisia using alternative state concepts ‐ the establishment component

Abstract. We evaluated the potential for restoring riparian grass and sedge meadows currently dominated by Artemisia tridentata var. tridentata with an experiment in which we burned sites with low, intermediate, and high water tables, i.e., dry, intermediate, and wet sites. To define the alternative states and thresholds for these ecosystems, we examined burning and water table effects on both abiotic variables and establishment of grasses adapted to relatively high (Poa se‐cunda ssp. juncifolia), intermediate (Leymus triticoides), or low (L. cinereus) water tables. Wet sites had lower soil temperatures and higher soil water contents than dry sites. Burning increased soil temperatures on all sites. Undershrub microsites on control plots had the lowest temperatures, while former undershrub microsites on burn plots had the highest temperatures. Surface soil water was low on burn plots early in the growing season due to desiccation, but higher at deeper depths after active plant growth began. Emergence was generally greater on wet sites, but survival was microsite‐ and species‐specific. Undershrub microsites on control plots facilitated emergence and first‐year survival, but seedlings that survived initially harsh conditions on burn plots had similar numbers alive at the end. In general, favorable environments and establishment of species adapted to mesic conditions indicate that wet sites represent an alternative state of the naturally occurring dry meadow ecosystem type, and can be restored to grass and sedge meadows. Harsh environments and lack of establishment of species adapted to mesic conditions indicate that dry sites have crossed a threshold and may represent a new ecosystem type. Understory vegetation and seed banks on dry sites have been depleted, and restoration will require burning and reseeding with species adapted to more xeric conditions.