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1.
Teak(Tectona grandis Linn.f.) ranks among the top five tropical hardwood species and is being promoted for use in plantations in its non-native range due to its high economic value.However,there is a general lack of data on ecosystem functioning of teak plantations.We aimed at understanding storage and flux of nutrients related to young plantations of teak.Cycling of nitrogen(N) and phosphorus(P) in a chronosequence of plantations(1,5,11,18,24 and 30 years) was studied in the Moist Deciduous Forest Region of North India with the objective of investigating the nutrient cycling pattern at younger age since the current trend of harvesting age of the species in several tropical countries is being drastically reduced for quick return from this high value crop.Standing state,nutrient uptake,nutrient return and nutrient retranslocation in these plantations were estimated by tree harvesting and chemical analysis methods.The range of total standing nutrient across all these plantations was 20.3 to 586.6 kg·ha-1 for N and 5.3 to 208.8 kg·ha-1 for P.Net uptake of N ranged from 19.4 to 88.9 kg·ha-1·a-1 and P from 3.8 to 18.1 kg·ha-1·a-1.Retranslocation of N and P among all the stands ranged from 8.7 to 48.0 kg·ha-1·a-1 and 0.01 to 3.5 kg·ha-1·a-1,respectively.Range of total nutrient return was 25.8 to 91.3 kg·ha-1·a-1 for N and 2.7 to 10.1 kg·ha-1·a-1 for P.N and P use efficiency was between 107.4 and 192.5 g dry organic matter(OM) g-1 N,and 551.9 and 841.1 g OM g-1 P,respectively.The turnover time ranged from 2.04-13.17 years for N and between 2.40-22.66 years for P.Quantity of N and P in the soil nutrient pool ranged from 2566.8 to 4426.8 kg·ha-1 and 372 to 520 kg·ha-1,Storage and flux of components in different plant parts of different aged plantations were assessed and depicted in compartment models.Percentage storage in soil,litter and vegetation ranged from 82% to 99%,0.6% to 2.4% and 0.5% to 15% for N,respectively,and from 63% to 98%,0.5% to 2% and 1% to 35% for P,respectively.This information could be useful in managing external nutrient manipulation to crops of different ages for optimum biomass production or carbon sequestration.  相似文献   

2.
马尾松林——三峡库区最主要的森林类型之一,对维持区域碳平衡具有非常重要的作用。本文以新田林场40 a~45 a生马尾松林生态系统为研究对象,同时结合铁山坪林场46 a~51 a生马尾松林文献资料,探讨了三峡库区马尾松林生态系统的生物量和碳分配格局。结果表明:马尾松林的总生物量约为140.00 t.hm-2,其中乔木层生物量所占比例大于80.00%。新田林场和铁山坪林场马尾松林生态系统的总碳储量分别为206.28 t.hm-2和197.78 t.hm-2,其中植被层约占1/3,土壤层占2/3。植被层中,乔木层碳储量占绝对优势。土壤层的碳储量主要集中于表层,土壤层碳储量呈现出随深度而降低的规律。与其它地区关于马尾松林的研究相比,年龄相近的林分,三峡库区的马尾松林碳储量偏低。因此,对三峡库区的马尾松林进行合理的经营管理,可能增加其固碳能力。  相似文献   

3.
There are many advantages of bended wood, such as good-looking shape, simple process and low cost. The product, however, is easy to get recovery, which is urgent to be dealt with. This paper concludes the features of deformation and recovery of bended wood and wood-based composites and summarizes four treating methods to keep dimensional stability. Compared to bended solid wood, some elementary perspectives on the research of bended wood-based composites are presented. The purpose of this paper is to suggest: 1) to investigate the optimum heating time and temperature that bended wood and wood-based composites need from the formation of deformation to the recovery and to the permanent fixation, according to its changes of dimensional stability such as curvature radius; 2) to measure the composites comprised of wood and adhesives on the changes of stress relaxation, dynamic viscoelasticity and crystallization field; 3) to quantitatively analyze changes of the major components in wood cell wall polymers as well as the composites under heat/steam treatment and untreated conditions. It will be helpful for subsequent research to clarify on the mechanisms of permanent fixation of bended wood and also contribute to that of wood-based composites.  相似文献   

4.
The study was conducted at Zengena forest, a fragmented remnant montane forest in northwestern Ethiopia, which surrounds Lake Zengena. The purpose was to assess the species composition, diversity and the regeneration status of woody plants. A total of 27 plots of 20 m × 20 m were sampled along the line transects laid down the altitudinal gradient from the edge of the forest encompassing the lake to the edge of the lake in eight aspects. In each plot, woody species were counted and the diameter at breast height and the height of trees and shrubs were measured. A total of 50 woody species belonging to 31 families were found, of which 17(34%) were trees, 7(14%) trees or shrubs, 23(46%) shrubs and 3(6%) lianas. The overall Shannon-Wiener diversity and evenness indices of woody species were 2.74 and 0.7, respectively. Clausena anisata had the highest relative density(23.5%), Rapanea rhododendroides the highest relative frequency(6.5%) and Prunus africana the highest relative dominance(45%) and importance value index(IVI, 51.6). The total basal area and density of woody plants were 22.3 m2?ha-1 and 2,202 individuals?ha-1, respectively. The population structure showed variations among woody plants and revealed varied regeneration patterns of different species. The importance value index and population structure revealed that some species are threatened and need prioritization for conservation measures. The results suggest that remnant forest patches in the highlands of northern Ethiopia host several woody plant species that are almost disappearing in other areas due to deforestation.  相似文献   

5.
Litter production, decomposition and nutrient release dynamics of Ochlandra setigera, a rare endemic bamboo species of Nilgiri biosphere were studied during 2011-2012 using the standard litter bag technique. Annual litter production was 1.981 t·ha-1 and was continuous throughout the year with monthly variations. Litterfall followed a triphasic pattern with two major peaks in November, 2011 and January, 2012 and a minor peak in July, 2011. The rate of decomposition in O. setigera was a good fit to the exponential decay model of Olson(1963). Litter quality and climatic conditions of the study site(maximum temperature, monthly rainfall and relative humidity) influenced the rate of decomposition. Nutrient release from the decomposing litter mass was in rank order N = Mg K = Ca P. Nutrient release from litter was continuous and it was in synchrony with growth of new culms. Study of litter dynamics is needed before introduction of a bamboo species into degraded or marginal lands or Agroforestry systems.  相似文献   

6.
Plantations of eucalypts as short-rotation tree crops are rapidly expanding in tropical and sub-tropical regions, including southern China, where the soils are acidic and available phosphorus(P) is limited. We investigated seedling growth, dry matter accumulation, and the dynamics of photosynthetic rate and chlorophyll content of seven Eucalyptus species/hybrids(E. dunnii, E. grandis, E. grandis × E. camaldulensis, E. urophylla × E. camaldulensis, E. urophylla × E. tereticornis, E. grandis × E. tereticornis, E. urophylla × E. grandis) in response to different levels of P supply(0, 6, 12 and 18 mg?kg-1 KH2PO4). The photosynthetic rate and the chlorophyll content significantly declined as the P supply declined in almost a linear fashion for all species as the P stress period extended. In the absence of P supply, height growth of seedlings of all species was significantly impaired, while root collar diameter growth and whole plant dry matter accumulation was not affected by the level of P supply in most of the species. Significant inter-species variations in growth, dry matter accumulation and photosynthetic rate in response to P supply were detected. Eucalyptus dunnii had the lowest growth performance across all levels of P supply while E. urophylla × E. tereticornis showed superior growth performance. From a practical point of view, E. urophylla × E. tereticornis is suggested as a candidate hybrid for planting on slightly P-deficient sites in southern China while E. dunnii, being a slow-growing species, is not suitable for short-rotation plantation. On plantation sites where severe P deficiency exists, P fertilization needs to be considered to boost rapid growth of seedlings so as to meet the management objectives of short-rotation plantation.  相似文献   

7.
We investigated the influence of different levels of osmotic stress on growth and development in selected wild almond species(eight Prunus spp.) grown in vitro. The study, while endorsing the efficacy of in vitro screening of auxiliary buds of wild almond for osmotic stress tolerance, showed species variability in its response to osmotic stress. Osmotic stress reduced growth and development of all the species. However, the putative tolerant Prunus spp. showed better performance than the putative susceptible genotypes. On average there was an 80% decrease in shoot dry weight at-1.2 MPa. Reduction in shoot weight was more common in osmotic stress-susceptible species in the section labeled ‘Euamygdalus'. The tolerant Prunus species produced smaller changes in biochemical responses than the sensitive cultivars for malondialdehyde content, catalase activity, relative permeability of protoplast membranes, and net photosynthetic rate. The tolerant species maintained cell integrity better than drought sensitive species. Wild almond species in the section labeled ‘Spartioides'(Prunus arabica(Olivier) Neikle, Prunus glauca (Browicz) A.E. Murray, Prunus scoparia Spach) and ‘Lycioides'(Prunus lycioides Spach, Prunus reuteri Bossi. et Bushe) were best adapted to osmotic stress. Increase in chlorophyll concentration and leaf thickness under high osmotic stress can be considered as preliminary selection parameters for osmotic stress tolerance in Prunus spp. The study confirmed the efficacy of the in vitro method for screening of large number of genotypes for osmotic stress tolerance in wild almond species.  相似文献   

8.
We investigated the fuel characteristics of five important bamboo species viz., Dendrocalamus strictus, D. brandisii, D. stocksii, Bambusa bambos and B. balcooa. The selected species cover more than 85% of the total growing stock of bamboo in India. Basic density varied from 0.48 to 0.78 g?cm-3 among the bamboo species studied. Ash content, volatile matter content and fixed carbon content ranged between 1.4%-3.0%, 77.2%-80.8% and 17.6%-21.1%, respectively. Variation in calorific value(18.7-19.6 MJ?kg-1) was marginal. Fuel value index varied widely(586-2120) among bamboo species. The highest calorific value(19.6 MJ?kg-1) and fuel value index(2120) were found in B. balcooa. Ash elemental analysis revealed that silica and potassium are the major ash forming minerals in bamboo biomass. Silica content ranged from 8.7% to 49.0%, while potassium ranged from 20.6% to 69.8%. We studied combustion characteristics under oxidizing atmosphere. Burning profiles of the samples were derived by applying the derivative thermogravimetric technique which is discussed in detail. The five bamboo species were different in their combustion behaviour, mainly due to differences in physical and chemical properties. We compare fuel properties, ash elemental analysis and combustion characteristics of bamboo biomass with wood biomass of Eucalyptus hybrid(Eucalyptus tereticornis × Eucalyptus camaldulensis).  相似文献   

9.
The status of agricultural non-point source (NPS) pollution in China is quite austere owing to lots of factors, the characteristics of which include severe N, P eutrophications in water bodies, unsuitable structure of agriculture and the lack of reasonable management. It was well known that forest could play an important role to control soil & water erosion, uptake extra soil nutrients as well. However forest coverage is rather low in the headwaters region. The research on the causes of NSP pollution and the significance by developing agroforestry to deal with the problem is presented in the paper, as well as the function of agroforestry and the related measures of pollution controlling, e.g., riparian forest buffer zones building. As a conclusion, controlling the loss of soil and water is regarded as an important crucial action and major research direction in the field. Thereby the benefits of pushing up agroforestry in slops to combat water eutrophication and prevent NSP pollution from worsening are significant.  相似文献   

10.
Loss of mangroves and consequent habitat fragmentation is a major concern throughout the world's tropical countries. Conversion of mangrove habitat due to aquaculture, agriculture, urbanization and industrialization, ecotourism, overlapping bureaucracy and conflicting policies is occurring at a striking rate. This paper reviews the trends of mangrove area changes in Bangladesh and compares them with four other countries in tropical regions that have significant mangrove areas. The rate of mangrove loss from the 1980 to 2005 was calculated using the compound interest rate formula for its explicit biological implication. In Bangladesh, the area of mangroves was found to have increased due to its higher accretion rate. In India the rate of mangrove loss had fallen. The rate of mangrove loss in Malaysia in the 1990s(-0.008 ha·a-1) was higher than the 1980s(-0.004 ha·a-1). In Indonesia, the rate decreased, from the 1980s(-0.018 ha·a-1) to the 1990s(-0.010 ha·a-1). Finally in Myanmar the rate of mangrove loss gradually accelerated. Aquaculture was found to be the common cause of mangrove conversion in the regions. Loss of mangroves is now a prominent global issue, associated with the loss of biodiversity, deterioration of habitat integrity, climatic changes, the amount of carbon sequestration, and resulting sea-level rise. Therefore, a systematic evaluation of these environmental impacts is prerequisite to realize sustainable mangrove management.  相似文献   

11.
Shebao Yu  Dan Wang  Wei Dai  Ping Li 《林业研究》2014,25(3):621-626
Understanding the age effect on soil carbon balance in forest ecosystems is important for other material cycles and forest management. In this research we investigated soil organic carbon density, litter production, litter decomposition rate, soil respiration, and soil microbial properties in a chronosequence of four Chinese fir plantations of 7, 16, 23 and 29 years at Dagangshan mountain range, Jiangxi Province, south China. There was a significant increasing trend in litter production with increasing plantation age. Litter decomposition rate and soil respiration, however, declined from the 7-year to the 16-year plantation, and then increased after 16 years. This was largely dependent on soil microorganisms. Soil carbon output was higher than carbon input before 16 years, and total soil carbon stock declined from 35.98 t·ha-1 in the 7-year plantation to 30.12 t·ha-1 in the 16-year plantation. Greater litter production could not explain the greater soil carbon stock, suggesting that forest growth impacted this microbial process that controlled rates of soil carbon balance together with litter and soil respiration. The results highlight the importance of the development stage in assessing soil carbon budget and its significance to future management of Chinese fir plantations.  相似文献   

12.
China is globally acknowledged as "Kingdom of Bamboo", and Zhejiang Province is nationally recognized as the first province of bamboo in China. Systematic and overall analysis is made by the approach of case study on why Zhejiang can get such a marvelous achievement so as to provide significant references and instructions for bamboo development for other countries who desire to learn technologies and know-how from China. The main contributions are concluded as below: 1) Quick progress of bamboo technology provides a strong back-up for bamboo industry development; 2) Governmental supports promote the balanced development of bamboo industry, including favorable policy, financial support; 3) Good relation of bamboo cultivation and processing; 4) Special soci-economic and humanitarian advantages for bamboo development, including good export environment, dynamic private economy, bamboo industry zone, excellent talents of bamboo; and 5) Quick expansion of international and domestic bamboo market stimulates and drives the development of bamboo industry  相似文献   

13.
The city of Tehran,like many polluted metropolises of the world,has higher emissions of greenhouse gases than other cities in Iran,due to heavy consumption of fossil fuel and landuse changes.To estimate carbon sequestration in two 40 year-old stands of planted Cupressus arizonica and Fraxinus rotundifolia in degraded lands surrounding Tehran,sampling of above-and below-ground biomass,soil(at two depths of 0-15 and 15-30 cm),and leaf litter was done by systematic random sampling.The total carbon stocks of C.arizonica and F.rotundifolia stands were respectively 328.20 and 150.69 Mg·ha-1.The aboveground biomass with 233.16(71%)Mg·ha-1 in C.arizonica and88.16(58.50%)Mg·ha-1 in F.rotundifolia contributed the most shares to carbon sequestration.The diameter at breast height,total height,basal area,total volume,and biomass of C.arizonica were significantly(p0.01)higher than those of F.rotundifolia.Also the depth of 0-30 cm of soil contributed between 18.29%and 32.15%of total ecosystem carbon,respectively.The economic value of carbon sequestration in the two stands in 2011 was calculated at 3.5 and 2.5 million dollars,respectively.Our results indicate that afforestation of the degraded land surrounding Tehran would sequester more carbon than would continuously degraded land,the current status quo.These stands can absorb atmospheric CO2 at different rates,thus tree species selection and stand development should be considered in planning future afforestation projects.  相似文献   

14.
A pot experiment was conducted to investigate the effects of nitrogen content [N1(no fertilizer), N2(0.15 g?kg–1), and N3(0.3 g?kg–1)] on the growth and the hydraulic characteristics of peach seedlings under different soil moisture conditions(W1, W2 and W3, in which the soil water content was 45% to 55%, 60% to 70%, and 75% to 80% of the field water capacity, respectively) by using a specialized high pressure flow meter with a root chamber and a coupling, which was connected to plant organs. Leaf area and leaf hydraulic conductivity(KL) increased significantly in the seedlings because of increased soil moisture and N content. KL increased with leaf area. A linear correlation was documented between KL and leaf area. KL was higher in the morning and began to decline sharply after 16:00, at which KL declined after an initial increase. Soil moisture and N content enhanced shoot(Ks) and root(Kr) hydraulic conductivities, thereby improving the low soil moisture condition to a large extent. Ks and Kr of the seedlings were reduced by 32% and 27% respectively in N1, and by 14.7% and 9.4%, respectively in N2, and both in W1, compared with the control treatment. N3 had no significant effect on Ks and Kr under similar conditions. Linear negative correlations were observed between Kr and the excised root diameter as well as between Ks and the shoot stem diameter. The shoot-to-root ratio increased with increase in N content. The shoot-to-root ratio in N3 was increased by 14.37%, compared with N1 in W1 as well as by 12% and 4.39% in W2 and W3, respectively. Knowledge of the effects of soil moisture and N fertilizer on hydraulic characteristics and growth is important. Our results provide basic guidelines for the implementation of water-saving irrigation and fertilization management of nursery stock.  相似文献   

15.
We report the results of carbon stored in soil and aboveground biomass from the most important area of mangroves in Mexico,with dominant vegetation of Red mangrove(Rhizophora mangle L.),Black mangrove(Avicennia germinans L.),white mangrove(Laguncularia racemosa Gaertn.)and button mangrove(Conocarpus erectus L.).We sampled soils with high fertility during the dry season in 2009 and 2010at three sites on Atasta Peninsula,Campeche.We used allometric equations to estimate above ground biomass(AGB)of trees.AGB was higher in C.erectus(253.18±32.17 t·ha-1),lower in A.germinans(161.93±12.63t·ha-1),and intermediate in R.mangle(181.70±16.58 t·ha-1)and L.racemosa(206.07±19.12 t·ha-1).Of the three studied sites,the highest absolute value for AGB was 279.72 t·ha-1in button mangrove forest at any single site.Carbon stored in soil at the three sites ranged from36.80±10.27 to 235.77±66.11 t·ha-1.The Tukey test(p0.05)made for AGB was higher for black mangrove showed significant differences in soil carbon content between black mangrove and button mangrove.C.erectus had higher AGB compared with the other species.A.germinans trees had lower AGB because they grew in hypersaline environments,which reduced their development.C.erectus grew on higher ground where soils were richer in nutrients.AGB tended to be low in areas near the sea and increased with distance from the coast.A.germinans usually grew on recently deposited sediments.We assumed that all sites have the same potential to store carbon in soil,and then we found that there were no significant differences in carbon content between the three samples sites:all sites had potential to store carbon for long periods.Carbon storage at the three sampling sites in the state of Campeche,Mexico,was higher than that reported for other locations.  相似文献   

16.
We investigated the effect of forest thinning on soil nitrogen mineralization, nitrification and transformation in a Cryptomeria japonica plantation at high elevation to provide basic data for forest management. We chose four study plots for control, light, medium and heavy thinning treatment, and three sub-plots for buried bag studies at similar elevations in each treatment plot to measure the net N mineralization and nitrification rates in situ. The contents of soil inorganic N(ammonium and nitrate) were similar between treatments, but all varied with season, reaching maxima in September 2003 and 2004. The seasonal maximum net Nmin rates after four treatments were 0.182, 0.246, 0.303 and 0.560 mg·kg-1·d-1 in 2003, and 0.242,0.258,0.411 and 0.671 mg·kg-1·d-1in 2004, respectively. These estimates are approximate with the lower annual rates of N mineralization for this region. Forest thinning can enhance net N mineralization and microbial biomass carbon. The percentage of annual rates of Nmin for different levels of forest thinning compared with the control plot were 13.4%, 59.8% and 154.2% in 2003, and 0.1%, 58.8% and 157.7% in 2004 for light, medium, and heavy thinning, respectively. These differences were related to soil moisture, temperature, precipitation, and soil and vegetation types. Well-planned multi-site comparisons, both located within Taiwan and the East-Asia region, could greatly improve our knowledge of regional patterns in nitrogen cycling.  相似文献   

17.
Forest fires occurrence is influenced by many factors, such as inter-annual weather variations and regional fuel distributions. Fires occurrence in different forest region has distinct spatial and temporal characteristics. The paper studied the natural forest fire environment in Northeastern China, as well as forest fires occurrence, burned area and fire seasons in Northeastern Forest Region. The result shows that more than 50% of annual burned area occurred in Northeast China Forest Region. Main fire seasons in the region are spring and autumn. Fires occurrence in spring is larger than that in autumn. There are few fires in summer. The authors' suggestions for fire management department are to emphasize the fuel management, improve the roads conditions, and enhance the fires control ability.  相似文献   

18.
Through sample plot survey and statistic analysis, this paper adopts ecological method to study the characteristics of plant diversity of forest vegetation in Luofu Mountain, Guangdong. The results show that there is a great plant diversity of forest vegetation in Luofu Mountain owing to the ascendancy of aqueous and thermal condition in subtropical zone. The total number of species in 4 500 m^2 sample plot(s) are 170 with 3 870 individual plants in total; Dahl species richness index (D) is 44.932; Simpson diversity index (L,D) is 0.022, 0.022; Simpson (1982) diversity index (D) is 3.806; Pielou evenness index (E) is 0, 984 and Hulbert evenness index (E) is 0.815; Shannon-wiener diversity index (information index H′) is 4.188; Asymmetry index (r) is 0.185. These indexes show that a better habitat will bring about plant diversity of forest vegetation, and the diversity of zonal vegetation shows that the higher latitude is, the less species of vegetation can be found. Besides, vertical change of plant diversity of forest vegetation in Luofu Mountain is obvious. Its species richness index and plant diversity index show that monsoon evergreen broad-leaved forest is the tallest, mountain evergreen broad-leaved forest follows as the second and conifer-broad-leaved mixed forest is the shortest. The Wilson β-diversity index, which is obtained by comparison between forest vegetation below 300 m and forest vegetation between 600-900 m, is 0.621. Calculated from comparison between forest vegetation in 600-1 100 m and forest vegetation in 900-1 100 m, the Wilson β-diversity index is 0.727; by comparing forest vegetation below 300 m with forest vegetation in 900-1 100 m, the Wilson β-diversity index is 1.877. This shows that the plant diversity of forest vegetation is affected by the change in gradient of elevation.  相似文献   

19.
The variability of main chemical composition of radial Chinese fir was studied. Analysis of variance showed that variance was significant, especially for holocellulose and α-celluloSe; the hblocellulose content in heart wood was lower than that in sapwood; the lignin content decreased from Position t to Position 3, but increased gradually from Position 4 to Position 8; the a ~ cellulose content in heart wood was lower than that in sapwood; and the relative crystallinity was 59.97% in Position 1, 60i80% in Position 2, and about 42% in others.  相似文献   

20.
A microbial inoculant, known as effective microorganisms(EM), was applied to determine its efficacy on seed germination and seedling growth in the nursery of Acacia auriculiformis A Cunn. ex Benth. The seedlings were grown in a mixture of sandy soil and cow dung(3:1) and kept in polybags; EM was poured at different concentrations(0.1%, 0.5%, 1%, 2%, 5% and 10%). Seed germination rate and growth parameters of seedlings – shoot and root lengths, fresh and dry weights of shoots and roots, vigor, volume, and quality indices and sturdiness – were measured. The nodulation status influenced by EM was also observed, along with the measurement of pigment contents in leaves. The highest germination rate(72%) was observed in 2% EM solution while the lowest(55%) was found in control treatment. The highest shoot and root lengths(30.6 cm and 31.2 cm respectively) were recorded in 2% EM and were significantly(p 0.05) different from control. Both fresh and dry weights of shoots were maximum(8.66 g and 2.99 g respectively) in 2% EM, whereas both fresh and dry weights of root were maximum(2.56 g and 1.23 g respectively) in 5% EM solution. Although the highest vigor index, volume index, and sturdiness(4450, 628 and 67.5 respectively) were found in 2% EM, the highest quality index(0.455) was found in 5% EM solution. The nodule number was higher at a very low(0.5%) concentration of EM but it normally decreased with the increase of concentration. The contents of chlorophyll a, chlorophyll b, and carotenoid were maximum(43.26 mg?L-1, 13.56 mg?L-1and 17.99 mg?L-1 respectively) in 2% EM. Therefore, low concentration of EM(up to 2%)can be recommended for getting maximum seed germination and seedling development of A. auriculiformis in the nursery.  相似文献   

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