Do biological expansion factors adequately estimate stand-scale aboveground component biomass for Norway spruce?

We developed site specific component (stem, branch, and foliage) biomass functions for two sites in Sweden (64° and 57° North latitude) where four treatments (control, irrigated, fertilized, irrigated plus fertilized) were applied in the existing Norway spruce stands (Picea abies L. Karst.) for 17 years. We tested for site effects in the component biomass equations and compared site specific biomass estimates to those generated using published functions ( 19 and 39). Site effects were significant for all components and indicated it would be unlikely to generate equations that well estimate biomass across the Norway spruce range as implicitly indicated in our efforts to generate species biomass expansion factors. We rejected our hypothesis that the published functions would well estimate component biomass for control plots. The published functions did not compare well with site specific component biomass estimates for the other treatments; both published functions well estimated stem mass up to stem mass of 25 Mg ha⁻¹, beyond which stem mass was overestimated, and both functions over and under estimated foliage and branch mass. Nor did the published functions compare well with each other, with stem, foliage and branch mass estimate differences of 12, 55, −8% and 11, 77, and 59% for the southern and northern sites, respectively, when averaged over all treatments and years. Adding limiting resources through fertilization increased stem, foliage and branch mass 57, 11, 18% and 120, 37, and 69% at the southern and northern sites, respectively, which would increase carbon sequestration and available stemwood and bioenergy materials. We recommend that more effort is spent in process-based modeling to better predict mass at a given site and ultimately provide better estimates of carbon sequestration and bioenergy material production changes.     

Influence of gaps on some selected tree characteristics of edge trees in Norway spruce plantations

The present study examined branch and stem characteristics of trees growing around gaps in Norway spruce plantations. Trees located at the edge of gaps with a radius of either 5 m or 7 m either unplanted or with supplementary planting were compared to trees in the original closed plantation. The experiment was carried out in two locations in the south of Sweden and the design included four blocks at each location and one replicate of each treatment in each block. The measurements were carried out on standing and felled trees in 2005 at the time of the first thinning. The results indicate a significant effect of gaps and supplementary planting on the diameter of the largest branch, the number of living branches close to breast height, branch basal area, height to the first living branch and taper. The effect of supplementary planting on branch and stem characteristics was greater in large gaps than in small ones. This study indicated that supplementary planting may be useful in affecting stem-form and branch parameters, although other studies have shown that the trees that result from supplementary planting contribute little to total production.     

Lipophilic extractives in different tree fractions and forestry assortments of Pinus sylvestris due for thinning or final cutting

The objectives were to determine the content and composition of lipophilic extractives, particularly fatty and resin acids, in three Scots pine trees from each of two stands in northern Sweden, one that was due for thinning and one due for final cutting. Extractives content of branches, needles, barks, stem discs from branch whorls, and sapwood and heartwood samples from various heights was measured. Fractions had very different concentrations and distributions of extractives due to differences in the composition of tissues. The needles had the highest total extractive concentration (around 150?kg/ton d.w.), followed by the branches, bark, timber from the final cut stand, and then the pulpwood and timber from the thinning stand. The final cut stand generally provided higher yields of extractives in assortments per hectare than the thinning stand; the difference was five-fold for timber, three-fold for whole trees, two-fold for branches, needles and bark and similar for pulpwood. This information on the content and composition of extractives in different tissues, and the dependence of these quantities on tree age could be used together with information on conventional stand data such as tree numbers and dimensions to guide the selection and management of feedstocks for biorefineries.     

Simulation of the long-term effects of different strategies for precommercial thinning in Pinus sylvestris

The influence of the intensity and timing of precommercial thinning (PCT) on stand development and financial return was studied in Scots pine stands. Functions describing the early development of the stand structure after PCT were developed. The functions were based on 195 plots within 41 PCT experiments in Sweden. The dimension distribution of the established stand was estimated and used as input to the decision support system Heureka, to simulate the stand development until final felling. The studied treatments included PCT to 1000, 2000 and 3000?stems?ha^?1 at mean heights of 2, 4 and 6 m. Separate simulations were carried out for different site fertilities. Mean annual volume increment increased with increasing number of stems after PCT whereas the timing of PCT had only a small effect. The land expectation value (LEV) generally decreased with increasing mean height at PCT, primarily because of the increased cost of PCT. LEV decreased with increasing number of stems after PCT at low fertility sites whereas only minor differences were found for PCT to 1000 and 2000?stems?ha^?1 at medium and high fertility sites. The general pattern persisted when different scenarios of future timber quality were simulated.     

济南市发展现代都市农业的主要模式与对策建议

都市农业是发展现代农业的重要载体。本课题在研究国内外都市农业发展趋势、深入调查分析济南市发展都市农业的优势条件及制约因素的基础上,提出了加快农业结构调整步伐、建立济南特色都市农业体系的政策建议。     

Modeling Landscape Vegetation Pattern in Response to Historic Land-use: A Hypothesis-driven Approach for the North Carolina Piedmont,USA

Current methods of vegetation analysis often assume species response to environmental gradients is homogeneously monotonic and unimodal. Such an approach can lead to unsatisfactory results, particularly when vegetation pattern is governed by compensatory relationships that yield similar outcomes for various environmental settings. In this paper we investigate the advantages of using classification tree models (CART) to test specific hypotheses of environmental variables effecting dominant vegetation pattern in the Piedmont. This method is free of distributional assumptions and is useful for data structures that contain non-linear relationships and higher-order interactions. We also compare the predictive accuracy of CART models with a parametric generalized linear model (GLM) to determine the relative strength of each predictive approach. For each method, hardwood and pine vegetation is modeled using explanatory topographic and edaphic variables selected based on historic reconstructions of patterns of land use. These include soil quality, potential soil moisture, topographic position, and slope angle. Predictive accuracy was assessed on independent validation data sets. The CART models produced the more accurate predictions, while also emphasizing alternative environmental settings for each vegetation type. For example, relic hardwood stands were found on steep slopes, highly plastic soils, or hydric bottomlands – alternatives not well captured by the homogeneous GLM. Our results illustrate the potential utility of this flexible modeling approach in capturing the heterogeneous patterns typical of many ecological datasets.     

The diagnosis of injuries to the intestines, gallbladder and bile ducts in the dog

Clinical and radiographic findings in three dogs with intestinal ruptures and four dogs with rupture of the gallbladder or bile ducts are described. In both types of injuries the onset of clinical signs was insidious, and the initial signs were masked by acute disorders such as bruises, fractures, pneumothorax or abdominal haemorrhage. With rupture of the gallbladder or bile ducts, there was listlessness, abdominal enlargement, icterus and clay-coloured stool. Diffuse peritonitis was seen radiographically. Paracentesis an danalysis of the abdominal fluid for bilirubin substantiated the diagnosis. Radiographically, ruptures of the intestine showed localized peritonitis and abnormal arrangement of the loops. Adhesions between intestines and omentum sealed off the ruptures, and only small amounts of intestinal contents leaked into the abdomen. Little or no free gas was seen on abdominal radiographs. Gas was sometimes trapped in pouches formed by the adhesions. In these rare injuries, prolonged observation of the patients and awareness of the clinical and radiographic findings are necessary to make an accurate diagnosis. Résumé. Résultats des examens cliniques et radiologiques de trois chiens de rupture intestinale et de quatre animaux présentant une rupture de la vésicule biliaire ou des voies biliaires. Dans les deux types de lésion le début des signes cliniques était insidieux et le tableau clinique masqué par les manifestations aiguës: contusions, fractures, pneumothorax ou hémorragie abdominale. Dans le cas de rupture de la vésicule ou des voies biliaires, on observe de l'apathie, une augmentation de volume de l'abdomen, de l'ictère et des selles de couleur argile. Les radiographies montrent une péritonite diffuse. La paracentèse et l'examen du liquide péritonéal (recherche de bilirubine) confirment le diagnostic. La rupture de l'intestin se traduit radiologiquement par une péritonite localisée et des anomalies de disposition des anses intestinales. Les adhérences entre celles-ci et l'épiploon assurent l'occlusion des ruptures, une quantité réduite de liquide s'épanchait ainsi dans la cavité abdominale; les radiographies de l'abdomen ne montrait que peu, ou pas du tout de gaz libre, qui parfois se localisait dans les poches formées par les adhérences. Au cours de ces lésions traumatiques une observation prolongée des sujets et la connaissance des signes cliniques et radiologiques sont nécessaires pour poser un diagnostic correct. Zusammenfassung. Klinische und radiographische Befunde an drei Hunden mit Eingeweiderissen und an vier Hunden mit Rissen der Gallenblase oder der äusseren Gallenwege werden beschrieben. Bei beiden Typen von Verletzungen war das Einsetzen der klinischen Merkmale insidiös, und die ersten Anzeichen wurden durch akute Erscheinungen wie Quet-schungen, Frakturen, Pneumothorax oder abdominale Blutungen verdeckt. Beim Riss der Gallenblase oder der Gallengänge wurden Mattigkeit, Hervortreten des Bauches, Ikterus und lehmfarbener Kot beobachtet. Radiographisch wurde diffuse Peritonitis festgestellt. Paracentese und die Analyse der Bauchflüssigkeit auf Bilirubin bestätigten die Diagnose. Radiographisch zeigten Eingeweiderisse lokalisierte Peritonitis und anomale Anordnung der Darmschlingen. Adhäsionen zwischen Därmen und Omentum verschlossen die Rupturen, und nur kleine Mengen des Darminhalts gelangten in die Bauchhöhle. Die Röntgenaufnahmen der Bauchhöhle zeigten wenig oder kein freies Gas. Manchmal wurde Gas in den von den Adhäsionen geformten Taschen festgehalten. Bei diesen seltenen Verletzungen sind längere Beobachtung der Patienten und die Kenntnis der klinischen und radiographischen Befunde für eine genaue Diagnose notwendig.     

Evaluation of environmental and management-related risk factors associated with chronic mastitis in sows

OBJECTIVE: To evaluate environmental and management-related risk factors associated with chronic mastitis in sows. ANIMALS: 1,254 sows from 76 herds. PROCEDURE: Prevalence of chronic mastitis was determined by a veterinarian who performed clinical examinations at the time of weaning and approximately 1 week later in a sample of the sow population on each farm. Information concerning environmental factors and management practices was collected. In addition, the herd veterinarian made an assessment of the farmer's skills in swine production. RESULTS: Use of partly slatted floors in the farrowing pens, use of disinfectants between batches in the farrowing and breeding areas, feeding lactating sows whey, and avoiding cutting or grinding of the piglets' teeth were significantly associated with a decreased risk of chronic mastitis. A high hygienic standard on the farm, as determined by the herd veterinarian, was associated with a significant reduction in the prevalence of mastitis. CONCLUSIONS AND CLINICAL RELEVANCE: Chronic mastitis in sows is a common disease that has a negative influence on productivity. Results indicate that certain management practices and environmental factors influenced the development of mastitis, which may contribute to the development of methods useful for controlling the disease.     

Effect of natural organic soil solutes on weathering rates of soil minerals

The rate at which minerals in the soil weather is affected by pH and concentration of organic solutes (DOC). The rates of release of Al, Ca, Fe, K, Mg, Na, P and Si from a mineral soil sample to solutions of natural organic solutes and HCI (control) were determined at pH 3 and 4 for up to 17 weeks. Soil solutions were collected by centrifuging materials of O horizons from various soil types under four tree species (spruce, birch, oak, beech) and passed through a cation-exchange resin to yield H⁺-saturated organic solutes. The acceleration of the elements' release by the organic solutes was shown directly by the relative ligand effect (RLE), that is, the release rate in the organic solute solution divided by the release rate in the HCI solution (control) at the same pH. The RLE was greater at pH 4 than at pH 3, and it decreased for the elements in the order Fe > Ca > Mg > Al ≈ Si > K ≈ Na. This indicates that natural organic solutes are more important weathering agents at higher than lower pH and for weathering of mafic minerals rich in Ca, Fe and Mg than of felsic minerals such as K- and Na-feldspars. For all elements and at both pHs, RLE was strongly correlated with the concentration of DOC, which was also closely correlated with titratable acidity of the organic solutes. The important effect of soil type and tree species in producing weathering-promoting organic solutes therefore seems to be expressed through the concentration and not the composition of the organic soil solutes.