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Ground vegetation,forest floor and mineral topsoil in a clear-cutting and reforested Scots pine stands of different ages:a case study

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Journal of Forestry Research 2022年第4期33卷 1247-1257页

作者： dovilėgustienė Iveta Varnagirytė-Kabašinskienė Vidas Stakėnas Lithuanian Research Centre for Agriculture and Forestry Liepųstr.1Girionys53101 Kaunas DistrictLithuania Kaunas Forestry and Environmental Engineering University of Applied Sciences Liepųstr.1Girionys53101 Kaunas DistrictLithuania

Scots pine(Pinus sylvestris L.)is a dominant tree species on nutrient-poor sandy soils in the Baltic region’s hemiboreal forests.A final clear-cut in commercial stands is a common ***,the maintenance of relatively stable vegetation indices and ecological processes throughout the rotation promote new scientific and social ***,clear-cuttings disturb forest functions for a certain period,i.e.,phytocenoses with forest-based species composition,biodiversity,and vegetation *** organic carbon(SOC)and nutrients can also be *** key indices,ground vegetation,SOC and main nutrients in the forest floor and in 40-cm topsoil layer were analysed in the clear-cuttings(not reforested)and in reforested 10-,30-,and 101-year-old Scots pine stands in *** results show an increase in species richness at the beginning of stand formation up to 30 years after clear-cutting;species typical of a mature forest occurred relatively quickly *** mean mass of forest floor vegetation was negatively related to the richness of ground vegetation *** floor p H consequently decreased with stand *** SOC levels were in the mature *** the mineral topsoil layers,total SOC and total nitrogen were in the upper 10-cm layer in the 30-year-old stand.A post-harvest peak in mineral N concentration was observed and other nutrients,especially mobile PO,KO,Caand Mg,increased the clear-cuttings and in the 10-year-old stand compared to the mature stand.

关键词： Pinus sylvestris Species cover Richness Soil organic carbon Soil nutrients Mature stand

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The main physical properties of planosol in maize(Zea mays L.) cultivation under different long-term reduced tillage practices in the Baltic region

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Journal of Integrative Agriculture 2015年第7期14卷 1309-1320页

作者： K?stutis Romaneckas Egidijus ?arauskis dovil? Avi?ienyt? Sidona Buragien? David Arney Institute of Agrosystems and Soil Sciences Aleksandras Stulginskis University Institute of Agricultural Engineering and Safety Aleksandras Stulginskis University Department of Nutrition and Animal Products Quality Institute of Veterinary Medicine and Animal Sciences Estonian University of Life Sciences

The impact of sustainable reduced tillage （RT） on the physical properties of soil is well documented worldwide; however, there is no precise information about the influence of long-term RT or no-till （NT） on the soils at the boundary for grain maize-growing in the semi-humid subarctic climate conditions of the Baltic states, especially on the formation of a hard- ened upper soil layer （10-15 cm in depth） --＂loosening hardpan＂. This study was carried out at the Research Station of Aleksandras Stulginskis University, Lithuania from 2009-2012. The investigations were based on a long-term （since 1988） field experiment. The aim of the investigation was to ascertain the influence of reduced primary tillage on the main soil＇s physical properties. This study examined soils that were deep ploughing （DP）, shallow ploughing （SP）, deep cultivation （DC）, shallow cultivation （SC）, and no-till （NT）. Reducing the tillage intensity to NT had no significant effect on the structural soil＇s composition; however, the stability of the structure of the 〉1 and 〉0.25 mm-size fractions was significantly higher in the non-reversibly tilled （DC, SC） and NT plots. The penetration resistance of the DP soils was less after primary tillage and wintering, and became similar to the NT plots at the end of the maize growth season. After primary tillage and wintering, the soil moisture content in the upper soil layer （0-5 cm depth） of the NT plots was 17-49 and 16-18% higher than that in the DP. Long-term reduction of primary tillage up to NT generally had no significant effect on the moisture content and soil bulk density of the 0-10 and 10-20 cm layers. The results showed that long-term RT stabilized the physical quality of soil. Less soil penetration resistance was established in the DP plots compared to both RT and NT, however, indicators of the formation of a uniform ＂loosening hardpan＂ layer were not found. It is summarized that long-term RT or NT systems stabilize, or may increase, the physical

关键词： bulk density maize moisture content penetration resistance reduced tillage soil aggregation

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Direct nanoscopic observation of plasma waves in the channel of a graphene field-effect transistor

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Light(Science & Applications) 2020年第1期9卷 1079-1085页

作者： Amin Soltani Frederik Kuschewski Marlene Bonmann Andrey Generalov Andrei Vorobiev Florian Ludwig Matthias M.Wiecha dovile Cibiraite Frederik Walla Stephan Winnerl Susanne C.Kehr Lukas M.Eng Jan Stake Hartmut G.Roskos Physikalisches Institut Johann Wolfgang Goethe-UniversitatMax-von-Laue-Str.1D-60438 Frankfurt am MainGermany Institut für Angewandte Physik Technische Universitat DresdenNöthnitzer Str.61D-01187 DresdenGermany Department of Microtechnology and Nanoscience Chalmers University of TechnologySE-41296 GothenburgSweden Institute of Ion Beam Physics and Materials Research Helmholtz-Zentrum Dresden-RossendorfBautzner Landstraße 400D-01328 DresdenGermany Complexity and Topology in Quantum Matter(CT.QMAT) Cluster of Excellence EXC 2147Dresden/WurzburgGermany Department of Electronics and Nanoengineering Aalto UniversityTietotie 302150EspooFinland

Plasma waves play an important role in many solid-state phenomena and *** also become significant in electronic device structures as the operation frequencies of these devices increase.A prominent example is field-effect transistors(FETs),that witness increased attention for application as rectifying detectors and mixers of electromagnetic waves at gigahertz and terahertz frequencies,where they exhibit very good sensitivity even high above the cut-off frequency defined by the carrier transit *** theory predicts that the coupling of radiation at THz frequencies into the channel of an antenna-coupled FET leads to the development of a gated plasma wave,collectively involving the charge carriers of both the two-dimensional electron gas and the gate *** this paper,we present the first direct visualization of these *** graphene FETs containing a buried gate electrode,we utilize near-field THz nanoscopy at room temperature to directly probe the envelope function of the electric field amplitude on the exposed graphene sheet and the neighboring antenna *** of the field distribution documents that wave injection is unidirectional from the source side since the oscillating electrical potentials on the gate and drain are equalized by capacitive *** plasma waves,excited at 2 THz,are overdamped,and their decay time lies in the range of 25-70 *** this short decay time,the decay length is rather long,i.e.,0.3-0.5μm,because of the rather large propagation speed of the plasma waves,which is found to lie in the range of 3.5-7×10^(6)m/s,in good agreement with *** propagation speed depends only weakly on the gate voltage swing and is consistent with the theoretically predicted 1/4 power law.

关键词： antenna channel transistor

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