Understory dynamics after disturbance accelerate succession from spruce to beech-dominated forest—the Siggaboda case study     

Andreas Bolte  Lutz Hilbrig  Britt Maria Grundmann  Andreas Roloff 《Annals of Forest Science》2014,71(2):139-147

??Context

It is assumed that climate change will favour European beech (Fagus sylvatica L.) to Norway spruce (Picea abies [L.] Karst.) at its northern range margins due to climate change and induced disturbance events.

??Aims

An old-growth mixed forest of spruce and beech, situated near the northern beech margin, was studied to reveal effects of disturbances and response processes on natural forest dynamics, focussing on the understory.

??Methods

We carried out analyses on understory dynamics of beech and spruce in relation to overstory release. This was done based on a sequence of stand and tree vitality inventories after a series of abiotic and biotic disturbances.

??Results

It became apparent that beech (understory) has a larger adaptive capacity to disturbance impacts and overstory release (68 % standing volume loss) than spruce. Understory dynamics can play a key role for forest succession from spruce to beech-dominated forests. Disturbances display an acceleration effect on forest succession in the face of climate change.

??Conclusion

Beech is poised strategically to replace spruce as the dominant tree species at the study area. Due to an increasing productivity and a lower risk of stand failure, beech may raise into the focus of forestry in southern Sweden.  相似文献   

The Effect of Five Stocking Densities on Growth and Yield of Red Swamp Crawfish Procambarus clarkii   总被引：1，自引：0，他引：1  

CHarles G.  Lutz William R.  Wolters 《Journal of the World Aquaculture Society》1986,17(1-4):33-36

A 34-day study was conducted to estimate the effect of stocking density on growth, biomass, and yield of harvestable animals in red swamp crawfish, Procambarus clarkii (Girard). Juvenile crawfish were stocked at l, 2, 4, 8, and 16 crawfish per m² into plastic-lined metal pools planted with rice ( Oryza sativa ) with three replicate pools at each density. Crawfish averaged 35 ± 1.5 mm (SE) total length at the time of stocking.
Growth in total length and weight was significantly affected by density ( P < 0.01), ranging from 91.5 mm and 20.7 g for crawfish stocked at 1 per m² to 62.5 mm and 6.3 g for crawfish stocked at 16 per m². The total crawfish biomass ranged from 20.7 g per m² for crawfish stocked at 1 per m² to 88.7 g per m² at 16 per m². The portion of that biomass made up of harvestable sized animals (>75 mm total length) ranged from 100% at 1 per m² to 0.7% at 16 per m². Gross revenues per ha were projected for crawfish yields at each stocking density with and without a graded product.  相似文献   

Hardwiring the brain: endocannabinoids shape neuronal connectivity     

Berghuis P  Rajnicek AM  Morozov YM  Ross RA  Mulder J  Urbán GM  Monory K  Marsicano G  Matteoli M  Canty A  Irving AJ  Katona I  Yanagawa Y  Rakic P  Lutz B  Mackie K  Harkany T 《Science (New York, N.Y.)》2007,316(5828):1212-1216

The roles of endocannabinoid signaling during central nervous system development are unknown. We report that CB(1) cannabinoid receptors (CB(1)Rs) are enriched in the axonal growth cones of gamma-aminobutyric acid-containing (GABAergic) interneurons in the rodent cortex during late gestation. Endocannabinoids trigger CB(1)R internalization and elimination from filopodia and induce chemorepulsion and collapse of axonal growth cones of these GABAergic interneurons by activating RhoA. Similarly, endocannabinoids diminish the galvanotropism of Xenopus laevis spinal neurons. These findings, together with the impaired target selection of cortical GABAergic interneurons lacking CB(1)Rs, identify endocannabinoids as axon guidance cues and demonstrate that endocannabinoid signaling regulates synaptogenesis and target selection in vivo.  相似文献   

Einfluß von Sorte und Phosphordüngung auf den Phosphorgehalt und die Aktivität der sauren Phosphatasen von Weizen und Gerste. — Ein Beitrag zur Diagnose der P-Versorgung von Pflanzen —     

Wilhelm Rmer  Lutz Beißner  Harald Schenk  Albrecht Jungk 《植物养料与土壤学杂志》1995,158(1):3-8

Influence of cultivar and phosphorus application on P concentration and acid phosphatase activity in wheat and barley. — A contribution to the diagnosis of P supply of plants — Acid phosphatase activity compared to total P concentration was studied as a diagnostic criterion of the phosphorus nutritional status of wheat and barley. In a field experiment with wheat cv ‘Sperber’ the influence of P level on P_ase activity and P concentration was monitored at four developmental stages. Significant correlations with grain yield were found for P_ase activity at all four stages whereas P concentration was significantly correlated with grain yield in the early stage (DC 26–27) only. Genetic variability and influence of P supply on P_ase activity and P concentration was studied at low and at high P supply with 9 wheat and 23 barley cultivars grown for 4 and 5 weeks in pot experiments. The variability of P_ase activity caused by cultivars was higher than that caused by P supply. It is, therefore, concluded that the acid phosphatase activity is not suitable as a generally applicable tool for diagnosing P supply. In comparison, total P concentration of the plants was influenced to a higher degree by P supply than by cultivars. Total P is, therefore, more suitable as a criterion for diagnosing P supply of plants than P_ase activity. The samples, though, have to be collected in stages before DC 27.  相似文献   

Estimating surface porosity by roughness measurement in a silt‐loam field     

Yurui Sun  Jianhui Lin  Peter Schulze Lammers  Lutz Damerow 《植物养料与土壤学杂志》2006,169(5):630-632

  相似文献   

Zur Charakterisierung von Biozoenose und Biotop des Übergangs-Moorwaldes     

J. L. Lutz  H. Poschenrieder  Th. Beck  G. Ronde  H. Schmeidl  J. Schwaibold 《European Journal of Forest Research》1957,76(9-10):257-277

  相似文献   

Molecule cascades     

Heinrich AJ  Lutz CP  Gupta JA  Eigler DM 《Science (New York, N.Y.)》2002,298(5597):1381-1387

Carbon monoxide molecules were arranged in atomically precise configurations, which we call "molecule cascades," where the motion of one molecule causes the subsequent motion of another, and so on in a cascade of motion similar to a row of toppling dominoes. Isotopically pure cascades were assembled on a copper (111) surface with a low-temperature scanning tunneling microscope. The hopping rate of carbon monoxide molecules in cascades was found to be independent of temperature below 6 kelvin and to exhibit a pronounced isotope effect, hallmarks of a quantum tunneling process. At higher temperatures, we observed a thermally activated hopping rate with an anomalously low Arrhenius prefactor that we interpret as tunneling from excited vibrational states. We present a cascade-based computation scheme that has all of the devices and interconnects required for the one-time computation of an arbitrary logic function. Logic gates and other devices were implemented by engineered arrangements of molecules at the intersections of cascades. We demonstrate a three-input sorter that uses several AND gates and OR gates, as well as the crossover and fan-out units needed to connect them.  相似文献   

The force needed to move an atom on a surface     

Ternes M  Lutz CP  Hirjibehedin CF  Giessibl FJ  Heinrich AJ 《Science (New York, N.Y.)》2008,319(5866):1066-1069

Manipulation of individual atoms and molecules by scanning probe microscopy offers the ability of controlled assembly at the single-atom scale. However, the driving forces behind atomic manipulation have not yet been measured. We used an atomic force microscope to measure the vertical and lateral forces exerted on individual adsorbed atoms or molecules by the probe tip. We found that the force that it takes to move an atom depends strongly on the adsorbate and the surface. Our results indicate that for moving metal atoms on metal surfaces, the lateral force component plays the dominant role. Furthermore, measuring spatial maps of the forces during manipulation yielded the full potential energy landscape of the tip-sample interaction.  相似文献   

Plaggic Anthrosol: Soil of the Year 2013 in Germany: An overview on its formation,distribution, classification,soil function and threats          下载免费PDF全文

Luise Giani  Lutz Makowsky  Klaus Mueller 《植物养料与土壤学杂志》2014,177(3):320-329

The Plaggic Anthrosol (German: Plaggenesch) has been elected “Soil of the Year 2013” in Germany. This article reviews present knowledge on the formation, distribution, classification, soil functions, and threats of Plaggic Anthrosols. As the colors of Plaggic Anthrosols differ, we introduce a “Grey Plaggic Anthrosol” and a “Brown Plaggic Anthrosol”. The term Plaggic Anthrosols is used in WRB, whereas those soils are classified as Agrosems according to the Russian, as Plagganthrepts according to the US Soil Taxonomy, and Plaggenesch according to the German taxonomy. The formation of Plaggic Anthrosols is the result of a former arable land use technique, the plaggen agriculture, starting ≈ 1000 y ago and lasting since the introduction of mineral fertilization. During processing plaggen agriculture, plaggen or sods of humic topsoil horizons were cut in the landscape, carried to the stables, enriched with dung, and subsequently spread out onto the fields as an organic‐earthy manure. The manure decomposed and humified, whereas the mineral fraction remained and raised the land surface by 0.1 cm y^–1 in average. Hence, the diagnostic horizon, a thick (70–130 cm) humus‐rich man‐made epipedon, often containing artefacts, was formed over time. The main region of spatial distribution of Plaggic Anthrosols is NW Germany, The Netherlands and NE Belgium. Minor occurrences are reported from other parts of Europe. Compared to the associated soils, Plaggic Anthrosols hold considerable natural, archive and utilization functions, but are threatened by degradation when their use as arable soil is rendered.  相似文献   

Evaluation of recombinant human thyroid-stimulating hormone to test thyroid function in dogs suspected of having hypothyroidism     

Boretti FS  Sieber-Ruckstuhl NS  Favrot C  Lutz H  Hofmann-Lehmann R  Reusch CE 《American journal of veterinary research》2006,67(12):2012-2016

OBJECTIVE: To evaluate the use of recombinant human (rh) thyroid-stimulating hormone (TSH) in dogs with suspected hypothyroidism. ANIMALS: 64 dogs with clinical signs of hypothyroidism. PROCEDURES: Dogs received rhTSH (75 microg/dog, IV) at a dose independent of their body weight. Blood samples were taken before and 6 hours after rhTSH administration for determination of total serum thyroxine (T(4)) concentration. Dogs were placed into 1 of 3 groups as follows: those with normal (ie, poststimulation values indicative of euthyroidism), unchanged (ie, poststimulation values indicative of hypothyroidism; no thyroid gland stimulation), or intermediate (ie, poststimulation values between unchanged and normal values) post-TSH T(4) concentrations. Serum canine TSH (cTSH) concentration was determined in prestimulation serum (ie, before TSH administration). RESULTS: 14, 35, and 15 dogs had unchanged, normal, and intermediate post-TSH T(4) concentrations, respectively. Basal T(4) and post-TSH T(4) concentrations were significantly different among groups. On the basis of basal serum T(4) and cTSH concentrations alone, 1 euthyroid (normal post-TSH T(4), low basal T(4), and high cTSH concentrations) and 1 hypothyroid dog (unchanged post-TSH T(4) concentration and low to with-in reference range T(4) and cTSH concentrations) would have been misinterpreted as hypothyroid and euthyroid, respectively. Nine of the 15 dogs with intermediate post-TSHT(4) concentrations had received medication known to affect thyroid function prior to the test, and 2 of them had severe nonthyroidal disease. CONCLUSIONS AND CLINICAL RELEVANCE: The TSH-stimulation test with rhTSH is a valuable diagnostic tool to assess thyroid function in selected dogs in which a diagnosis of hypothyroidism cannot be based on basal T(4) and cTSH concentrations alone.  相似文献