Assessing the utility of ALOS PALSAR and SPOT 4 to predict timber volumes in even-aged Eucalyptus plantations located in Zululand,South Africa     

Riyad Ismail  Horst Kassier  Morries Chauke  Francesco Holecz  Nico Hattingh 《Southern Forests》2015,77(3):203-211

In commercial forestry, regular terrestrial enumerations of the growing stock are required for the valuation, sustain-able management and planning of current and future timber supplies. In this study we examined whether the combination of synthetic aperture radar (ALOS PALSAR) and optical satellite (SPOT 4) image data can accurately predict the timber volume of even-aged Eucalyptus plantations located in South Africa. Results from this study show that the combination of ALOS PALSAR and SPOT 4 produces a R ² value of 0.68 for the planted model, whereas the coppiced model produced a R ² value of 0.55. However, by including stand age as an independent variable in the stepwise model, there was a 15% improvement for the planted model, whereas the coppiced model produced a 27% improvement. The final model developed in this study produced a R ² value of 0.83 and a RMSE of 31.71?m³ ha?1 for planted stands, whereas the model for coppiced stands produced a R ² value of 0.82 and a RMSE of 27.70?m³ ha?1. As it is not practical or financially feasible for commercial forestry companies to carry out terrestrial enumerations for all plantations on an annual basis, the model developed in this study presents an alternative and accurate method to calculate timber volume for even-aged Eucalyptus plantations.  相似文献   

ON THE SIZE OF THE LITTER AND THE GESTATION PERIOD OF PROCAVIA CAPENSIS     

VAN DER Horst CJ 《Science (New York, N.Y.)》1941,93(2418):430-431

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Physiological proteomics of the uncultured endosymbiont of Riftia pachyptila     

Markert S  Arndt C  Felbeck H  Becher D  Sievert SM  Hügler M  Albrecht D  Robidart J  Bench S  Feldman RA  Hecker M  Schweder T 《Science (New York, N.Y.)》2007,315(5809):247-250

The bacterial endosymbiont of the deep-sea tube worm Riftia pachyptila has never been successfully cultivated outside its host. In the absence of cultivation data, we have taken a proteomic approach based on the metagenome sequence to study the metabolism of this peculiar microorganism in detail. As one result, we found that three major sulfide oxidation proteins constitute approximately 12% of the total cytosolic proteome, which highlights the essential role of these enzymes for the symbiont's energy metabolism. Unexpectedly, the symbiont uses the reductive tricarboxylic acid cycle in addition to the previously identified Calvin cycle for CO2 fixation.  相似文献   

An extremely luminous panchromatic outburst from the nucleus of a distant galaxy     

Levan AJ  Tanvir NR  Cenko SB  Perley DA  Wiersema K  Bloom JS  Fruchter AS  Postigo Ade U  O'Brien PT  Butler N  van der Horst AJ  Leloudas G  Morgan AN  Misra K  Bower GC  Farihi J  Tunnicliffe RL  Modjaz M  Silverman JM  Hjorth J  Thöne C  Cucchiara A  Cerón JM  Castro-Tirado AJ  Arnold JA  Bremer M  Brodie JP  Carroll T  Cooper MC  Curran PA  Cutri RM  Ehle J  Forbes D  Fynbo J  Gorosabel J  Graham J  Hoffman DI  Guziy S  Jakobsson P  Kamble A  Kerr T  Kasliwal MM  Kouveliotou C  Kocevski D  Law NM  Nugent PE  Ofek EO  Poznanski D 《Science (New York, N.Y.)》2011,333(6039):199-202

Variable x-ray and γ-ray emission is characteristic of the most extreme physical processes in the universe. We present multiwavelength observations of a unique γ-ray-selected transient detected by the Swift satellite, accompanied by bright emission across the electromagnetic spectrum, and whose properties are unlike any previously observed source. We pinpoint the event to the center of a small, star-forming galaxy at redshift z = 0.3534. Its high-energy emission has lasted much longer than any γ-ray burst, whereas its peak luminosity was ～100 times higher than bright active galactic nuclei. The association of the outburst with the center of its host galaxy suggests that this phenomenon has its origin in a rare mechanism involving the massive black hole in the nucleus of that galaxy.  相似文献   

Photic induction of mPer1 and mPer2 in cry-deficient mice lacking a biological clock   总被引：1，自引：0，他引：1  

Okamura H  Miyake S  Sumi Y  Yamaguchi S  Yasui A  Muijtjens M  Hoeijmakers JH  van der Horst GT 《Science (New York, N.Y.)》1999,286(5449):2531-2534

Mice lacking mCry1 and mCry2 are behaviorally arrhythmic. As shown here, cyclic expression of the clock genes mPer1 and mPer2 (mammalian Period genes 1 and 2) in the suprachiasmatic nucleus and peripheral tissues is abolished and mPer1 and mPer2 mRNA levels are constitutively high. These findings indicate that the biological clock is eliminated in the absence of both mCRY1 and mCRY2 (mammalian cryptochromes 1 and 2) and support the idea that mammalian CRY proteins act in the negative limb of the circadian feedback loop. The mCry double-mutant mice retain the ability to have mPer1 and mPer2 expression induced by a brief light stimulus known to phase-shift the biological clock in wild-type animals. Thus, mCRY1 and mCRY2 are dispensable for light-induced phase shifting of the biological clock.  相似文献   

Pyogenic bacterial infections in humans with MyD88 deficiency     

von Bernuth H  Picard C  Jin Z  Pankla R  Xiao H  Ku CL  Chrabieh M  Mustapha IB  Ghandil P  Camcioglu Y  Vasconcelos J  Sirvent N  Guedes M  Vitor AB  Herrero-Mata MJ  Aróstegui JI  Rodrigo C  Alsina L  Ruiz-Ortiz E  Juan M  Fortuny C  Yagüe J  Antón J  Pascal M  Chang HH  Janniere L  Rose Y  Garty BZ  Chapel H  Issekutz A  Maródi L  Rodriguez-Gallego C  Banchereau J  Abel L  Li X  Chaussabel D  Puel A  Casanova JL 《Science (New York, N.Y.)》2008,321(5889):691-696

MyD88 is a key downstream adapter for most Toll-like receptors (TLRs) and interleukin-1 receptors (IL-1Rs). MyD88 deficiency in mice leads to susceptibility to a broad range of pathogens in experimental settings of infection. We describe a distinct situation in a natural setting of human infection. Nine children with autosomal recessive MyD88 deficiency suffered from life-threatening, often recurrent pyogenic bacterial infections, including invasive pneumococcal disease. However, these patients were otherwise healthy, with normal resistance to other microbes. Their clinical status improved with age, but not due to any cellular leakiness in MyD88 deficiency. The MyD88-dependent TLRs and IL-1Rs are therefore essential for protective immunity to a small number of pyogenic bacteria, but redundant for host defense to most natural infections.  相似文献   

Effects of nitrogen supply on growth and nitrogen uptake by Miscanthus sinensis during establishment     

Franz Wiesler  Joachim Dickmann  Walter J. Horst 《植物养料与土壤学杂志》1997,160(1):25-31

The effect of nitrogen (N) supply on growth and N uptake of Miscanthus sinensis during the establishment was determined. Seven different N addition regimes were compared in a nutrient solution experiment. In the treatments N111 (severe deficient), N222 (moderate deficient), N333 and N444 (optimal for maximum growth) different N concentration ranges were held constant during the entire growing season. In the treatments N144, N414 and N441 plants were subjected to low (1) N concentration in one of three experimental periods, whereas the N concentration was high (4) in the other two periods. Depending on the N demand of the plants, N concentrations were adjusted to 250–500 μM (N1), 500–1000 μM (N2), 1250–2500 μM (N3) and 2500–5000 μM (N4) when the N concentration in the N222 treatment had dropped below 100 μM. The other elements in the solution were replenished according to the estimated element ratios in the plants. As a reference the potassium concentration in the solution was measured regularly. During the first year plants with a non-limited N supply (N444) produced new tillers and increased the length of individual tillers until the end of the growing season. This resulted in a 48% shoot dry matter increase late in the growing season between August and October and a linear increase of cumulative N uptake between July and October. Limited N supply during the entire growing season (N111, N222) caused lower shoot yields but rhizome and particularly root dry weights were less affected. Significant final yield losses were also observed when the N supply was limited only during the first 7 weeks of growth (N144). By contrast, final shoot yield was hardly affected when the plants were exposed to limited N supply over a period of 9 weeks at the end of the growing season (N441). In the second year regrowth of shoots in spring was affected by the previous year's N supply, since five weeks after the beginning of regrowth, shoot dry matter was significantly positively correlated with N contents in rhizomes and shoots in the previous October. Our results show, that N supply at the beginning of the growing season has a major effect on final yield in the first establishment year of M. sinensis. However, from the second year on, the capacity of N reserves in rhizomes and roots affects spring growth much more than current N supply.  相似文献   

Aluminum inhibits apoplastic flow of high–molecular weight solutes in root apices of Zea mays L.     

Mayandi Sivaguru  Walter J. Horst  Dejene Eticha  Hideaki Matsumoto 《植物养料与土壤学杂志》2006,169(5):679-690

Using an aluminum (Al)‐sensitive maize cultivar, we investigated the influence of Al on the apoplastic solute bypass flow and its relationship with Al‐induced (1 h, 50 μM) callose formation and root growth. We selected the fluorescent probes 8‐hydroxypyrene‐1,3,6‐trisulfonic acid, trisodium salt (MW 524) (HPTS) and dextran‐Texas Red (TR) conjugates (MW 3,000, 10,000, and 40,000) to monitor their apoplastic transport. Confocal laser–scanning microscopy (CLSM) analysis and spectrofluorometric quantification showed Al‐induced callose formation in peripheral root cells within 1 h. Pretreatment of plants with the callose synthesis inhibitor 2‐deoxy‐D‐glucose (DDG) reduced the callose formation by half. Uptake experiments with both HPTS and dextrans showed uniform dye distribution in control root apices. After Al treatment for 1 or 2 h, which inhibited root growth by 32% or 50%, respectively, the dyes accumulated in the epidermal and outer cortical cell layers, especially in the 1–2 mm apical root zone. Al treatment reduced the export of the dyes out of the apical 1 cm treatment zone. This was due to strong sorption of HPTS but not of dextrans by Al‐loaded cell walls. Aluminum treatment reduced loading into the xylem sap particularly of higher–molecular weight dextrans. Pretreatment of roots with DDG and presence of 50 mM mannitol during the Al treatment partially forestalled the inhibitory effect of Al on the dye transport, but only slightly reduced the Al‐induced growth inhibition. Exudation experiments revealed that xylem water flow remained unaffected by the Al treatment of the root tips. The results with dextran suggest that Al binding in cell walls of the root apex inhibits apoplastic bypass flow of higher–molecular weight solutes, which might contribute to Al‐induced inhibition of root growth.  相似文献   

Root to shoot translocation of macronutrients in relation to shoot demand in maize (Zea mays L.) grown at different root zone temperatures     

Christof Engels  Horst Marschner 《植物养料与土壤学杂志》1992,155(2):121-128

Root growth and nutrient uptake rates of maize (Zea mays L.) are decreased at low root zone temperatures (RZT) and thus, shoot growth may be limited by nutrient deficiency. The objectives of this research were to characterize the shoot demand for nutrients per unit root at suboptimal RZT and to relate net translocation rates of N, P, K, and Ca from the roots to the shoot to shoot demand. Maize plants were grown for 11 days in soil or 8 days in nutrient solution at uniform shoot (24°/20°C, day/night) but different RZT (12°, 18°, and 24°C). The shoot base of the plants (apical shoot meristem and zone of leaf extension) was either kept within or above the cooled root zone. Shoot and root growth were significantly reduced at suboptimal RZT (12°, 18°). Lifting the shoot base above the cooling zone increased shoot growth markedly, whereas root growth was not significantly influenced. Thus, the shoot fresh weight increment day^?1 g^?1 root fresh weight (i.e. the shoot demand per unit root) was increased by a factor of up to 9 for plants with their shoot base above as compared to within the cooling zone. At suboptimal RZT, translocation rates of N, K, and Ca to the shoot remained low in plants with the shoot base in the cooling zone but were higher than in 24°C-grown plants, when the shoot base was above the cooling zone. In both nutrient solution- and soil-grown plants translocation rates of N, K, and Ca were closely correlated with the shoot demand per unit root but less to RZT. In contrast, the translocation rate of P was mainly affected by RZT but insensitive to shoot demand and, therefore, was always higher at a RZT of 24° than of 12°C. From these results it is suggested, that at low RZT the root-to-shoot translocation rates of N, K, and Ca are mainly determined by the shoot demand, whereas the translocation rate of P, regardless of the shoot demand, is reduced by a direct effect of low temperature on the roots.  相似文献   

Abschätzung von N2O-Emissionen mit Hilfe eines Windtunnels - ein Methodenvergleich     

Christof Braun  J. Braschkat  T. Mannheim  Walter R. Fischer  Horst Marschner 《植物养料与土壤学杂志》1994,157(4):265-269

Estimation of N₂O-losses with a windtunnel - a comparison of methods No systematical investigations into the interactions between NH₃-emissions and N₂O-losses with different kinds of sludge applications have published so far. The use of a windtunnel, which is used for NH₃-measurements, as a possible alternative method to measure N₂O-emissions should be tested. Simultaneous measurements with open chambers and a windtunnel on a Catena in the country of Kraichgau (Baden-Württemberg) were done. Changing the construction of the windtunnel, it was possible to optimize the N₂O-measurements and to eliminate constructional mistakes. But still the dilution factor is too big to take representative amounts of N₂O.  相似文献