Above-ground biomass dynamics after reduced-impact logging in the Eastern Amazon     

Lucas Mazzei  Plinio Sist  Ademir Ruschel  Francis E. Putz  Phidias Marco  Wagner Pena  Josué Evandro Ribeiro Ferreira 《Forest Ecology and Management》2010

Changes in above-ground biomass (AGB) of 17 1 ha logged plots of terra firme rain forest in the eastern Amazon (Brazil, Paragominas) were monitored for four years (2004–2008) after reduced-impact logging. Over the same time period, we also monitored two 0.5 ha plots in adjacent unlogged forest. While AGB in the control plots changed little over the observation period (increased on average 1.4 Mg ha⁻¹), logging resulted in immediate reductions in ABG that averaged 94.5 Mg ha⁻¹ (±42.0), which represented 23% of the 410 Mg ha⁻¹ (±64.9) present just prior to harvesting. Felled trees (dbh > 55 cm) accounted for 73% (±15) of these immediate losses but only 18.9 Mg ha⁻¹ (±8.1) of biomass was removed in the extracted logs. During the first year after logging, the annual AGB balance (annual AGB gain by recruitment and growth − annual AGB loss by mortality) remained negative (−31.1 Mg ha⁻¹ year⁻¹; ±16.7), mainly due to continued high mortality rates of damaged trees. During the following three years (2005–2008), average net AGB accumulation in the logged plots was 2.6 Mg ha⁻¹ year⁻¹ (±4.6). Post-logging biomass recovery was mostly through growth (4.3 ± 1.5 Mg ha⁻¹ year⁻¹ for 2004–2005 and 6.8 ± 0.9 Mg ha⁻¹ year⁻¹ for 2005–2008), particularly of large trees. In contrast, tree recruitment contributed little to the observed increases in AGB (1.1 ± 0.6 Mg ha⁻¹ year⁻¹ for 2004–2005 and 3.1 ± 1.3 Mg ha⁻¹ year⁻¹ for 2005–2008). Plots with the lowest residual basal area after logging generally continued to lose more large trees (dbh ≥70 cm), and consequently showed the greatest AGB losses and the slowest overall AGB gains. If 100% AGB recovery is desired and the 30-year minimum cutting cycle defined by Brazilian law is adhered to, current logging intensities (6 trees ha⁻¹) need to be reduced by 40–50%. Such a reduction in logging intensity will reduce financial incomes to loggers, but might be compensated for by the payment of environmental services through the proposed REDD (reduced emissions from deforestation and forest degradation) mechanism of the United Nations Framework Convention on Climate Change.  相似文献   

Effects of nickel supply on the fattening performance and several biochemical parameters of broiler chickens and rabbits     

Bersényi A  Fekete SG  Szilágyi M  Berta E  Zöldág L  Glávits R 《Acta veterinaria Hungarica》2004,52(2):185-197

Broiler chicken and rabbit experiments were carried out to study the effects of nickel (Ni) supplementation on growth performance and Ni metabolism. ROSS cockerels and New Zealand White female rabbits were fed a diet containing Ni in concentrations of 0, 50 and 500 mg/kg in dry matter (DM). Dietary supplementation of 50 mg Ni/kg slightly improved the body weight gain (BWG) and had a beneficial effect on the feed conversion efficiency (FCE) in broiler chickens. However, Ni added at a level of 500 mg/kg significantly (P < 0.05) reduced the BWG by 10% and resulted in significantly (P < 0.05) worse (2.3 +/- 0.2 kg/kg) FCE. The relative weight of the liver in cockerels was significantly (P < 0.05) decreased by Ni as compared to the control group (1.7 and 2.1% vs. 2.6%). The activity of AST and CHE enzymes was increased insignificantly by dietary supplementation of 500 mg Ni/kg, indicating damage of the liver parenchyma. The results of serum biochemistry were confirmed by a mild or moderate form of pathological focal fatty infiltration of the liver in broilers. Supplemental Ni of 50 mg/kg concentration resulted in non-significantly increased BWG in rabbits. Ni added to the diet at a level of 500 mg/kg reduced the digestibility of crude protein by 3-4% and that of crude fibre by 20-25% in rabbits. Approx. 98% of the ingested Ni was lost from the body via the faeces, 0.5-1.5% via the urine and approx. 1% was incorporated into the organs of rabbits. As a result of dietary supplementation of 50 and 500 mg Ni/kg, Ni accumulated in the kidneys (4.9 +/- 0.5 and 17.1 +/- 3.1 vs. 1.9 +/- 0.3 mg/kg DM), ribs (10.3 +/- 0.4 and 10.4 +/- 0.6 vs. 9.1 +/- 0.6 mg/kg DM), heart (1.4 +/- 0.2 and 2.5 +/- 0.4 vs. 1.0 +/- 0.1 mg/kg DM) and liver (1.3 +/- 0.1 and 2.2 +/- 0.2 vs. 0.9 +/- 0.05 mg/kg DM), as compared to the control animals. It can be stated that supplementation of the diet with 50 mg Ni/kg had slight but non-significant beneficial effects on the growth performance of broiler chickens and rabbits.  相似文献   

Capsaicinoids in vegetative organs of Capsicum annuum L. in relation to fruiting     

Estrada B  Bernal MA  Díaz J  Pomar F  Merino F 《Journal of agricultural and food chemistry》2002,50(5):1188-1191

Pepper (cv. Padrón) shows a spatial gradient in the content of phenolic compounds, and particularly of capsaicinoids, along the stem. These compounds were consistently more abundant in apical fruits than in fruits belonging to middle and basal segments. Analysis of the two principal capsaicinoids in fruits showed that the proportion of capsaicin was always higher than that of dihydrocapsaicin. Capsaicinoids were also found to be present in vegetative organs, such as stem and leaves. In this case, the proportion of individual capsaicinoids was different than that in fruits, and dihydrocapsaicin was found to be more abundant. To find out whether the capsaicinoids in vegetative organs came from the fruits, the floral buds were removed and fruit formation was prevented. Capsaicinoids were not detected in the stem and leaves of floral bud-deprived plants, suggesting that they did originate from the fruit.  相似文献   

Untersuchungen zur Inaktivierung einiger Enzyme durch Wasserblanchieren bei der Pommes frites-Herstellung     

Barbara Fretzdorff  W. Bergthaller  B. Putz 《Potato Research》1988,31(1):25-36

Zusammenfassung In der modernen Herstellung vorfritierter Kartoffelstreifen für Pommes frites werden zur Qualit?tsverbesserung zumeist Blanchierschritte eingesetzt. Deren Wirkung kann über die Bestimmung der Restaktivit?t verschiedener Enzyme kontrolliert werden. Gewaschene Kartoffelstreifen (Cv. Bintje und Granola) wurden in einer kontinuierlich arbeitenden Pilot-Anlage für vorfritierte, tiefgefrorene Kartoffelstreifen für Pommes frites unter Variation der Blanchiertemperatur (50, 60, 70, 80 und 90°C) und der Blanchierzeit (2, 4, 6 und 8 min) wasserblanchiert. In tiefgefrorenen Proben der blanchierten/vorfritierten Kartoffelstreifen wurden die Restaktivit?ten der Enzyme Peroxidase (POD), Lipoxygenase (LOX) und lipolytischer Acylhydrolase (LAH) bestimmt. Bei der eingesetzten Rohware wies die Sorte Bintje h?here Enzymaktivit?ten auf als die Sorte Granola. Beim Wasserblanchieren von Kartoffelstreifen nahm die thermische Stabilit?t der untersuchten Enzyme in folgender Reihenfolge ab: POD>LOX>LAH. Die Inaktivierung auf Restaktivit?ten<1% erfolgte bei LAH bei 4 min/70°C, bei LOX bei 2 min/80°C und bei POD bei 4 min/90°C. In den vorfritierten Kartoffelstreifen konnten keine Restaktivit?ten mehr nachgewiesen werden. Ver?ffentl.-Nr. 5564 der Bundesforschungsanstalt für Getreide- und Kartoffelverarbeitung, 4930 Detmold, Bundesrepublik Deutschland.  相似文献   

Eye movement-retina delayed feedback     

Smith KU  Putz V  Molitor K 《Science (New York, N.Y.)》1969,166(3912):1542-1544

Time delays between ocular movement and retinal input have been studied by yoking a visual target to eye movement by experimental programming methods and a laboratory real-time computer system. The subject's task was to manipulate this eye movement-yoked target cursor to perform either compensatory or pursuit eye tracking. The computer thereafter was programmed to store input eye-movement signals and read them out after a delay interval to control the yoked visual target cursor controlled by the eye movements. Delay time constants of 0.1 second significantly affected tracking. Eye movement-retinal feedback delays appeared to have an even more marked effect on positive pursuit eye tracking.  相似文献   

In reply: oldest pinniped     

Berta A  Wyss AR 《Science (New York, N.Y.)》1990,248(4954):499-500

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The effect of harvest time on the accumulation of reducing sugars during storage of potato (Solanum tuberosum L.) tubers: Experimental data described, using a physiological based, mathematical model     

M. L. A. T. M. Hertog  B. Putz  L. M. M. Tijskens 《Potato Research》1997,40(1):69-78

Summary The physiological based mathematical model describing the storage behaviour of potato (Solanum tuberosum) tubers was examined to determine its ability to explain the changing storage behaviour as a function of harvest time for ten different cultivars. Between 90 to 98% of the observed variance was accounted for. This confirmed the models concept that the maturity at time of harvest determines the storage behaviour through the initial amount of the enzyme (or enzyme system) responsible for cold induced sweetening.  相似文献   

The effects of gonadal development and sex steroids on growth hormone secretion in the male tilapia hybrid (Oreochromis niloticus × O. aureus)     

Philippa Melamed  Noa Eliahu  Michal Ofir  Berta Levavi-Sivan  Jean Smal  Francoise Rentier-Delrue  Zvi Yaron 《Fish physiology and biochemistry》1995,14(4):267-277

Profiles of plasma growth hormone (GH) in male tilapia hybrid (Oreochromis niloticus x O. aureus) were measured and compared at different times of the year. The profiles did not appear to be repetitive, however, differences in their nature were observed at the different seasons; the most erratic profiles were seen in the height of the reproductive season (July), while the peaks were more subdued in the spring and disappeared in the autumn. Peaks in male fish were more prominent than in the females when measured in July. Perifused pituitary fragments from fish with a high GSI responded to salmon gonadotropin-releasing hormone (sGnRH) analog (10 nM-1 M), while those from fish with a low GSI barely responded to even the highest dose. Exposure of perifused pituitary fragments from sexually-regressed fish to carp growth hormone-releasing hormone (cGHRH; 0.1 M) or sGnRH (I M) stimulated GH release only after injection of the fish with methyl testosterone (MT; 3 injections of 0.4 mg kg ¹). The same MT pretreatment did not alter the response to dopamine (DA; 1 or 10 M). GH pituitary content in MT-treated fish was lower than in control fish, which may be explained by the higher circulating GH levels in these fish, but does not account for the increased response to the releasing hormones. Castration abolished the response of cultured pituitary cells to sGnRH (I fM-100 nM) without altering either their basal rate of secretion or circulating GH levels. Addition of steroids to the culture medium (MT or estradiol at 10 nM for 2 days) enabled a GH response to sGnRH stimulation in cells from sexually regressed fish. Pituitary cells which had not been exposed to steroids failed to respond to sGnRH, although their response to forskolin or TPA was similar to that of steroid-exposed cells. It would appear, therefore, that at least one of the effects of the sex steroids on the response to GnRH is exerted proximally to the formation of cAMP, or PKC, presumably at the level of the receptor. An increase in the number of receptors to the GH-releasing hormones, following steroid exposure, would explain also the changing nature of the GH secretory profile in different stages of the reproductive season.  相似文献