Daily time course of whole-shoot gas exchange rates in two drought-exposed Mediterranean shrubs

Effects of drought on water relations, whole-shoot gas-exchange characteristics, and pigment and zeatin concentrations were investigated in the Mediterranean shrubs rosemary (Rosmarinus officinalis L.) and lavender (Lavandula stoechas L.). Two-year-old, greenhouse-grown plants were placed in a whole-shoot gas-exchange measurement system and subjected to 10 days of drought, resulting in severe water stress, and then re-watered for 5 days in order to study their recovery. Water stress resulted in a significant decline in maximum whole-shoot net CO2 assimilation rates (An) for both species that was associated with reductions in leaf area and stomatal conductance. Because shoot dark respiration rate (Rd) was less sensitive to water stress than An, shoot Rd/An ratio increased from about 15 to 95% during water stress. No major changes in chlorophyll and carotenoid concentrations of rosemary leaves were observed during the experiments, but chlorophyll and carotenoid concentrations fell significantly in water-stressed lavender leaves. Zeatin concentrations were higher in rosemary leaves than in lavender leaves during water stress. After re-watering, whole-shoot An and Rd rapidly recovered to their pre-drought rates.     

Shoot development and dieback in progenies of Nothofagus obliqua

Shoot growth and dieback were compared among progenies of nursery-grown seedlings of Nothofagus obliqua belonging to seven progenies of the same provenance (Quila-Quina, Argentina). First-year shoots consisted of one growth unit (GU) and second-year shoots of one or two GUs. The probability of development of two GU was similar for all progenies. Progenies were different in terms of shoot size, terminal bud abscission, the extent of shoot dieback after shoot extension and the node of origin of the relay shoot on the first shoot. Plants with a second-year shoot consisting of two GUs had a thicker stem and more nodes than those with single-GU shoots. The selection of N. obliqua seed trees based on architectural traits suitable for forestry development at specific sites must contemplate variability among progenies and their probabilities of successful development under different conditions.     

Spatial pattern of the density of Armillaria epiphytic rhizomorphs on tree collar in an oak stand

The density of Armillaria gallica epiphytic rhizomorphs on tree collar was mapped in a young stand of pedunculate oaks (Quercus robur). A quick method to estimate the rhizomorph density was developed, investigating 19 trees, and was used in the subsequent study. The method consists of measuring the frequency of rhizomorphs present on a grid applied to an exposed small area of the tree collar. The pattern in tree collar rhizomorph density was closely related to the pattern of stump colonization by Armillaria and stumps were therefore important as inoculum sources. Rhizomorph density on tree collar showed a strong aggregated spatial pattern which could not be explained by variability in the soil characteristics, in particular waterlogging, or by a spatial pattern in tree vigour. Moreover, rhizomorph density on tree collar did not depend on their dominance status.     

A comparison of two stand table projection methods for young Eucalyptus nitens (Maiden) plantations in Chile

The study compares two methods of stand table projection based on data from young Eucalyptus nitens (Maiden) plantations in Chile. The projected diameter distributions were estimated using the methods proposed by Nepal and Somers (1992) [For. Sci. 38 (1992) 120] and Cao and Baldwin (1999) [For. Sci. 45 (1999) 506]. The evaluation compared the observed and estimated diameter distributions for different projection intervals, using the Kolmogorov–Smirnov test and an error index called ‘relative discrepancy’. The evaluation showed that both methods are suitable for application in the Eucalypt plantations. However, the method proposed by Nepal and Somers proved to be more accurate, especially when the projection period extends over 4 years or more. Expected error and bias for the observed and estimated total and merchantable volumes at stand level were also evaluated. The observed error and bias were relatively low for both methods; however, some differences were detected when the volume distributions were analyzed at diameter class level.     

A method for automatic collimator alignment in microdensity measurements

Summary In microdensitometry, based on X-ray absorption technique and a direct, electronic detector technique, it is usually not possible to observe the collimator and its alignment to the annual ring under investigation during the measurement. In this paper a method for automatic alignment of the collimator to the ring is described. The operating technique is based on an optimization of the resolution of the instrument at every annual ring while the collimator is rotated to the best position. The procedure has been in use a number of years and has proven itself to be efficient and reliable. The theory of operation for the procedure is described and its software structure is shown in a block diagram. Advantages and limitations of the procedure are discussed.The funding of this project is made by Nordbanken. The density profile in Fig. 5 has been recorded by Mr. Bo Larsson and is published with his kind permission     

Crystalline structure of heat-treated Scots pine [<Emphasis Type="Italic">Pinus sylvestris</Emphasis> L.] and Uludağ fir [<Emphasis Type="Italic">Abies nordmanniana</Emphasis> (Stev.) subsp. <Emphasis Type="Italic">bornmuelleriana</Emphasis> (Mattf.)] wood

The aim of this study was to determine changes in crystallinity and crystalline unit cell type of heat-treated Scots pine (Pinus sylvestris L.) and Uludağ fir (Abies nordmanniana stev. subsp. bornmuelleriana Mattf.) wood samples by means of FT-IR spectroscopic method. Heat treatment was applied on the test samples in an oven at three different temperatures (120, 150, and 180°C) and for two different periods of time (6 and 10 h) under atmospheric pressure. It was designated that crystallinity of both Scots pine and Uludağ fir wood samples increased during heat treatment depending on the duration. However, monoclinic structure in crystalline unit cells of Scots pine and Uludağ fir wood samples converted to triclinic structure when heat treated. It was estimated that monoclinic structure was dominant in the crystalline unit cell. It was established that the crystalline structure of Scots pine wood samples was more affected by heat treatment than that of Uludağ fir wood samples.     

Effect of temperature and compression on the mechanical behavior of steam-treated wood

The mechanical behavior of steamed spruce wood changes dramatically with compression along the grain, the change being much more moderate perpendicular to the grain. The stiffness decrement due to increased temperature is greatest in the tangential material direction. The stiffness decrement due to compression is greatest along the grain. Compression to 80% compressive strain at 131°C inverts the order of the material directions regarding stiffness, the stiffness being the least along the grain. Plastic strain due to compression is greater at higher temperatures. The compression-induced decrement of stiffness along the grain is greater at higher temperatures, but the off-axis decrement of stiffness is less at higher temperatures.     

Tree-ring: a suitable implement for spatial and temporal fire distribution analysis in savanna woodland and dry forest

Based on 120 stem discs collected during3 months of fieldwork along a 12 km route,the history of fires in the Wari Maro Forest(09 1000 N–02 1000E) over the past century in savanna woodland and dry forest was reconstituted.Three major ecological areas are characterized:one highly burnt zone located between two relative less burnt areas.By analyzing tree rings,246 fire scars were identified.The scars were caused by 51 fire years,occurring at a mean interval of 2.23 years.From 1890 to1965,only 6 years with fires were recorded from sampled trees.Since 1966,no year has passed without fire.The fire frequency point scale reached 14 years.This was the case of Burkea africana,which has been identified as a species tolerant to fire and could be planted to create a natural firewall.In contrast,Anogeissus leiocarpa is highly sensitive to fire,and in a dry forest ecosystem that burns seasonally,it requires a special conservation plan.Two new concepts are described:the rebarking of trees after fire and Mean Kilometer Fire Interval.The first concept was tested with Daniellia oliveri(Rolfe) Hutch & Dalz trees,and the second concept was used to evaluate spatial fire distribution.We demonstrate that savanna woodland and dry forest were subject to a degradation process caused by destructive fires related to vegetation cover clearance and illegal logging.     

Milk production,intake, digestion,blood parameters,and ingestive behavior of cows supplemented with by-products from the biodiesel industry

This study aimed to evaluate the intake, digestion, blood parameters, and feeding behavior of crossbred dairy cows (Holstein?×?Gir) managed on Panicum maximum Jacq. cv. Tanzania-1 and provided supplementation with groundnut cake, sunflower cake, or palm kernel cake (to replace soybean meal). Sixteen cows were randomly assigned in a Latin square design with four treatments and four experimental periods. The consumption of nutrients from the pasture did not vary between experimental treatments. Cows receiving the palm kernel cake supplement had a reduced crude protein, non-fibrous carbohydrate, and total digestible nutrient intake and an increase in the average consumption of ether extract. There was also a reduction in the digestibility of dry matter. The inclusion of supplements in the diet did not influence the average time spent eating, ruminating, or resting. The mean values of respiratory and heart rates showed thermal comfort during the trial period. There was a reduction in blood urea nitrogen with palm kernel cake supplementation, and the values of total protein, albumin, and glucose were also significantly different with this supplement. It is recommended that cakes of groundnut cake and sunflower cake seed be used for a total replacement of soybean meal supplements for lactating cows, but the use of palm kernel cake is not recommended.

     

Gill Reaction to Pollutants from the Tamiš River in Three Freshwater Fish Species,Esox lucius L. 1758, Sander lucioperca (L. 1758) and Silurus glanis L. 1758: A Comparative Study

The study evaluated the effects of waterborne pollutants from the Tami? River on gill histology and possible differences in gill reaction patterns between three freshwater fish species, pike Esox lucius L. 1758, pike‐perch Sander lucioperca (L. 1758) and wels catfish Silurus glanis L. 1758 from the Tami? River. Gills from analysed fish species showed moderate to intense histopathological alterations. The most frequent progressive alteration was hyperplasia of epithelium, whereas the most frequent regressive alteration was epithelial lifting. Circulatory disturbances were most often manifested in the form of hyperaemia. During comparative analysis, differences in gill indices, reaction and alteration indices, as well as in gill and filament prevalence between analysed species, were observed. Although all analysed fish species did show both progressive and regressive alterations, there was a significant difference in the level of expression of these reaction patterns. Gill index obtained for pike clearly stands out as the lowest. Wels catfish showed the highest progressive reaction index, significantly higher in comparison with the other two species (P < 0.05), while pike‐perch showed the highest regressive reaction index, also significantly higher in comparison with the other species (P < 0.001). These results may implicate species‐specific gill reactions and thus present a useful tool for better understanding toxic mechanisms of various pollutants.