592 research outputs found
The Effects of Different Intensity of Thinning on the Development in Scots Pine (Pinus sylvestris L.) Stands in Kazakh Uplands
The search for more accurate methods of predicting the growth and development of forest stands became the most urgent task set for foresters of Kazakhstan to determine the permissible interventions in the natural course of the life of plantings, provide high durability and resilience in forests. The aim of the study was to identify the effects of diameter and density of Scots pine stands of Kazakh Uplands on their growth and productivity and the related productivity of single plantation stands taking into account the conditions of growth and development of internal factors as well as further study of the methodology for assessing the forestry cost-effectiveness and improvement thinning. To achieve this aim, effects of varied felling intensities on Scots pine stands were studied. The most common two forest types in upland Scots pine forests were chosen as permanent sample plots; the dead pine-lichen and moss pine-grass. The results showed that improvement thinning of moderate and severe intensity which are more profitable should be done in Scots pine forests of Kazakh Upland as well as carrying out such thinning increases the yield of the larger logs and increases the value of the left stand
Review of the fast growing forest tree species in Turkey
Los antecedentes de la utilización de especies de
crecimiento rápido en Turquía tienen se remontan a
50 años y en los últimos 35-40 años se ha abrodado
desde un punto de vista científico. Eucalyptus
camaldulensis Dehn., E. grandis W.Hill., Pinus
pinaster Ait., P. radiata D. Don., chopos híbridos,
algunos clones de Populus deltoides Bartr. ex Marsh.
y P. nigra L. son las especies más importantes por su
mayor utilización en ensayos de especies, orígenes y
en plantaciones. Aunque las especies y orígenes
americanas son los más usados en los ensayos, los
resultados esperados no han podido ser alcanzados
debido al bajo número de clones y orígenes,
establecidos en los experimentos que no representan
el área de distribución natural. Junto con estas
especies, los estudios deberían centrarse en Pinus
brutia Ten. que tiene una amplia área de distribución
natural en Turquía, elevado potencial y caracteres
relacionados con el crecimiento rápido. Además, P.
brutia esta considerado como una especie que podría
cubrir el déficit de suministro a largo plazo. También,
los estudios deberían ocuparse de Fraxinus
angustifolia Wahl. subsp. oxycarpa Bieb ex Willd.,
Salix excelsa J. F. Gmelin., S. Alba L., Pterocarya
fraxinifolia Spach. y Alnus glutinosa Gaertn. subsp.
barbata (C. A. Mey.) Yalt que fueron probados en
varias regiones y mostraron mejores características
de crecimiento rápido que otras especies de aliso
indígenas._____________________________________The fast growing species have 50 year-old political
and 35-40 year-old scientific background in Turkey.
Eucalyptus camaldulensis Dehn., E. grandis W.Hill.,
Pinus pinaster Ait., P. radiata D. Don., hybrid
poplars, some clones of Populus deltoides Bartr. ex
Marsh. and P. nigra L. are the most important
species for obtaining a great deal of progress in
species and origin experiments and starting the
plantation phase in Turkey. In fast growing species
process; although the American species and origins
are mostly used, the desired outcomes could not be
achived because of establishing the experiments
with few number of clones and origins, which didn’t
represent the natural distribution area. Along with
these species, studies should be focused on Pinus
brutia Ten. which has broad natural distribution
area in Turkey, improvement potential and fast
growing character. Furthermore, P. brutia is
evaluated as a species which will close the supply
deficit in long run. Also, studies should be
performed on Fraxinus angustifolia Wahl. subsp.
oxycarpa Bieb ex Willd., Salix excelsa J. F.
Gmelin., S. alba L., Pterocarya fraxinifolia Spach.
and Alnus glutinosa Gaertn. subsp. barbata (C. A.
Mey.) Yalt. which was experimented in regional
base and showed the faster growing character than
the other indigenous alder species and native
species
The Finslerian wormhole models
We present models of wormhole under the Finslerian structure of spacetime.
This is a sequel of our previous work (Eur Phys J 75:564, 2015) where we
constructed a toy model for compact stars based on the Finslerian spacetime
geometry. In the present investigation, a wide variety of solutions are
obtained that explore wormhole geometry by considering different choices for
the form function and energy density. The solutions, like the previous work,
are revealed to be physically interesting and viable models for the explanation
of wormholes as far as the background theory and literature are concerned.Comment: 9 pages and 7 figue
Magnetic Field resulting from non-linear electrical transport in single crystals of charge-ordered Pr Ca MnO}
In this letter we report that the current induced destabilization of the
charge ordered (CO) state in a rare-earth manganite gives rise to regions with
ferromagnetic correlation. We did this experiment by measurement of the I-V
curves in single crystal of the CO system
PrCaMnO and simultanously measuring the magnetization
of the current carrying conductor using a high T SQUID working at T = 77K.
We have found that the current induced destabilization of the CO state leads to
a regime of negative differential resistance which leads to a small enhancement
of the magnetization of the sample, indicating ferromagnetically aligned
moments.Comment: 4 pages LateX, 4 eps figure
Non-linear electrical conduction and broadband noise in charge-ordered rare earth manganate Nd_0.5Ca_0.5MnO_3
Measurements of the dc transport properties and the low-frequency
conductivity noise in films of charge ordered Nd_0.5Ca_0.5MnO_3 grown on Si
subtrate reveal the existence of a threshold field in the charge ordered regime
beyond which strong non linear conduction sets in along with a large broad band
conductivity noise. Threshold-dependent conduction disappears as T -> T_{CO},
the charge ordering temperature. This observation suggests that the charge
ordered state gets depinned at the onset of the non-linear conduction.Comment: 3 pages of two-column text and 4 eps figure
Experiences on Establishment of Scots Pine (Pinus sylvestris L.) Plantation in Ash Dump Sites of Reftinskaya Power Plant, Russia
Since the middle of the last century in the Urals of Russia there has been a problem of environmental pollution by man-made emissions. The purpose of this investigation has been to summarize the recultivation experience of Reftinskaya power plant ash dump. The station was put into operation in 1970 and it is the largest one in Russia. Specific feature of the used coal is high content of ash (47%). Daily consumption of coal in winter period constitutes 48 thousand tons. Yearly emissions of the station constitute 400 thousand tons. The main components of the emissions are sulphureous anhydride (up to 40%) solid stuff (up to 50%) and nitric oxides. The Scots pine (Pinus sylvestris L.) plantations on ash dumps have shown good adaptation and growth. The plantations have formed 143 m(3)/ha total volume at the age of 20 in 1st site index of the recultivation site of the ash dump with ash layer up to 7 m. Weakly alkaline reaction of the ash spread by wind promoted soil dioxidation that results in soil fertility increasing significantly on territory of adjacent stands. Recultivation process includes two main stages which are ash dump surface covering with 25-40 cm soil layer, planting with 2-year old Scots pine (Pinus sylvestris L.) seedling
Laws of Black Hole Mechanics from Holst Action
The formulation of Weak Isolated Horizons (WIH) based on the Isolated Horizon
formulation of black hole horizons is reconsidered. The first part of the paper
deals with the derivation of laws of mechanics of a WIH. While the zeroth law
follows from the WIH boundary conditions, first law depends on the action
chosen. We construct the covariant phase space for a spacetime having an WIH as
inner boundary for the Holst action. This requires the introduction of new
potential functions so that the symplectic structure is foliation independent.
We show that a precise cancellation among various terms leads to the usual
first law for WIH. Subsequently, we show from the same covariant phase space
that for spherical horizons, the topological theory on the inner boundary is a
U(1) Chern-Simons theory.Comment: References added, Minor Corrections 25 pages 1 fi
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