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Impact of harvesting and fire on Phragmites australis reed quality in Tembe Elephant Park, Maputaland  [cached]
M.W. van Rooyen,C.A. Tosh,N. van Rooyen,W.S. Matthews
Koedoe : African Protected Area Conservation and Science , 2004, DOI: 10.4102/koedoe.v47i1.76
Abstract: In Maputaland, South Africa, the common reed (Phragmites australis) is used extensively for hut building, fencing, craftwork and thatching. As a result of over-harvesting most reed beds in communal areas have been degraded and are no longer producing reeds of the desired quality. At present the most productive reed beds are all found in conservation areas. The KwaMsomi area of the Muzi Swamp in the Tembe Elephant Park has been allocated to the Sibonisweni community for harvesting purposes. This community has recently requested Ezemvelo KwaZulu-Natal Wildlife for additional areas for harvesting on the grounds that the current site was no longer yielding reeds of suitable quality. The main objective of this study was therefore to determine whether there was a decline in reed quality in the KwaMsomi harvested area. The results of this study suggest that harvested areas contained more thin, short reeds than unharvested areas. Fire can be used to increase reed diameter in harvested areas, but will not significantly affect reed height. Ideally, reeds should only be harvested after the active growth period, when most of the nutrient reserves have been translocated to the rhizomes and the buds are still dormant. To improve reed quality a three-year rotational harvesting programme should be implemented to allow the reeds to recover fully before being harvested again.
Some characteristics of the sediments of healthy and degraded reed stands at Lake Fert /Neusiedler See
ágoston-Szabó, E.,Dinka, M.
Opuscula Zoologica Instituti Zoosystematici et Oecologici Universitatis Budapestinensis , 2009,
Abstract: Changes in the electric conductivity, pH, redox potential, temperature, PO43-, NH4+, NO3-, SO42-, S2-, Cl-, Na+, K+, Mg2+, Ca2+, total carbon (TC), total organic carbon (TOC) and total nitrogen (TN) concentrations of the sediment interstitial water and in the electron transport system activity (ETS), litter associated fungal biomass (as ergosterol), organic matter content (LOI) of the sediment were studied in healthy and degraded reed stands at the Hungarian part of Lake-Fert /Neusiedler See. Based on the results of the multivariate statistical analyses, significant differences have been found between the healthy and die-back sites.
Ecosystem Responses to Partial Harvesting in Eastern Boreal Mixedwood Stands  [PDF]
Suzanne Brais,Timothy T. Work,émilie Robert,Christopher D. O'Connor,Manuella Strukelj,Arun Bose,Danielle Celentano,Brian D. Harvey
Forests , 2013, DOI: 10.3390/f4020364
Abstract: Partial harvesting has been proposed as a key aspect to implementing ecosystem management in the Canadian boreal forest. We report on a replicated experiment located in boreal mixedwoods of Northwestern Quebec. In the winter of 2000–2001, two partial harvesting treatments, one using a dispersed pattern, and a second, which created a (400 m 2) gap pattern, were applied to a 90-year-old aspen-dominated mixed stand. The design also included a clear cut and a control. Over the course of the following eight years, live tree, coarse woody debris, regeneration and ground beetles were inventoried at variable intervals. Our results indicate that all harvesting treatments created conditions favorable to balsam fir ( Abies balsamea) sapling growth and trembling aspen ( Populus tremuloides) sapling recruitment. However, balsam fir and trembling aspen regeneration and ground beetles response to gap cuts were closer to patterns observed in clear cuts than in dispersed harvesting. The underlying reasons for these differing patterns can be linked to factors associated with the contrasting light regimes created by the two partial harvesting treatments. The study confirms that partially harvesting is an ecologically sound approach in boreal mixedwoods and could contribute to maintaining the distribution of stand ages at the landscape level.
Are the Economically Optimal Harvesting Strategies of Uneven-Aged Pinus nigra Stands Always Sustainable and Stabilizing?  [PDF]
Ignacio López-Torres,Sigfredo Ortu?o-Pérez,Fernando García-Robredo,Carmen Fullana-Belda
Forests , 2013, DOI: 10.3390/f4040830
Abstract: Traditional uneven-aged forest management seeks a balance between equilibrium stand structure and economic profitability, which often leads to harvesting strategies concentrated in the larger diameter classes. The sustainability (i.e., population persistence over time) and influence of such economically optimal strategies on the equilibrium position of a stand (given by the stable diameter distribution) have not been sufficiently investigated in prior forest literature. This article therefore proposes a discrete optimal control model to analyze the sustainability and stability of the economically optimal harvesting strategies of uneven-aged Pinus nigra stands. For this model, we rely on an objective function that integrates financial data of harvesting operations with a projection matrix model that can describe the population dynamics. The model solution reveals the optimal management schedules for a wide variety of scenarios. To measure the distance between the stable diameter distribution and the economically optimal harvesting strategy distribution, the model uses Keyfitz’s delta, which returns high values for all the scenarios and, thus, suggests that those economically optimal harvesting strategies have an unstabilizing influence on the equilibrium positions. Moreover, the economically optimal harvesting strategies were unsustainable for all the scenarios.
Danube Delta Biosphere Reserve (D.D.B.R.): reed dynamics within actual context  [PDF]
Silviu Covaliov,Mihai Doroftei,Jenic? Hanganu
Advances in Environmental Sciences , 2010,
Abstract: The reed beds are widely considered in Europe as ecologically and economically beneficialareas. In The Danube Delta Biosphere Reserve (D.D.B.R.), reed is by far the dominant species and reedmarshes cover more than 220,000 ha (Hanganu et al 2002). Presently, certain areas of reed beds areselected for burning or harvesting during the winter by private companies. Other surfaces are harvestedin green, mown by the inhabitants as cattle food. Comparing the present period with the harvestcampaigns from the ‘60th until the ‘80th, we can say that the actual pressure on reed’s biodiversity isreduced. All above aspects of management practices and their influence on reed beds succession andconservation of biodiversity are discussed. Beside the current reed type description and comparison withbiometrical data from Chifu et al (1993), we present their distribution, in relation with type of substrateand hydrology, by reed complexes.
Stochastic modeling of the number of felled trees in selection stands
Mitrovich, Slobodanka S.;
Computational & Applied Mathematics , 2005,
Abstract: this paper solves the problem of forecasting the number of trees in the selection stands predicted for harvesting in a future period, so that the main resource of the number of trees is sustained. this is achieved by stochastic modeling of the number of felled trees and by solving the certain partial differential equation.
Stochastic modeling of the number of felled trees in selection stands  [cached]
Slobodanka S. Mitrovich
Computational and Applied Mathematics , 2005,
Abstract: This paper solves the problem of forecasting the number of trees in the selection stands predicted for harvesting in a future period, so that the main resource of the number of trees is sustained. This is achieved by stochastic modeling of the number of felled trees and by solving the certain partial differential equation.
Regrowing Characteristic of GaN on Etched Pits by MOCVD
腐蚀坑处氮化镓二次MOCVD外延生长的特性

Lu Min,Fang Huizhi,Lu Shu,Li Zilan,Yang Hua,Zhang Bei,Zhang Guoyi,
陆敏
,方慧智,陆曙,黎子兰,杨华,章蓓,张国义

半导体学报 , 2004,
Abstract: GaN films etched in molten KOH are regrown for different hours.Scan electron microscope,X-ray diffraction,and photoluminence are applied to study the regrowing characteristics of the GaN in etched pits and nearly.The GaN film regrown for 2h has the lowest dislocation density and the best optical property.The slowly growing velocity in pits at early stage and the lateral growing at the edge of pits in late stage can restrain the propagation of pure screw threading dislocations.The asymmetrical regrowing characteristics on etch-pits will produce new edge threading dislocations and the connectivity of adjacent etch-pits can lessen edge threading dislocations.
Stochastic modeling of the number of trees and the number of felled trees in selection stands
Mitrovi? Slobodanka S.
Yugoslav Journal of Operations Research , 2004, DOI: 10.2298/yjor0401057m
Abstract: This paper solves the problem of forecasting the number of trees in the selection stands predicted for harvesting in a future period, so that the present resource of the number of trees is sustained. This is achieved by stochastic modeling of the number of trees and the number of felled trees and by solving the partial differential equation.
Quantum Reed-Muller Codes  [PDF]
Lin Zhang,Ian Fuss
Physics , 1997,
Abstract: This paper presents a set of quantum Reed-Muller codes which are typically 100 times more effective than existing quantum Reed-Muller codes.
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