We evaluated the phenology and litterfall dynamics of the mangrove Bruguiera gymnorrhiza（L.）Lamk along the Okukubi River, Okinawa Island, Japan.Over 3 years, this species showed the highest litterfall of leaves and ...We evaluated the phenology and litterfall dynamics of the mangrove Bruguiera gymnorrhiza（L.）Lamk along the Okukubi River, Okinawa Island, Japan.Over 3 years, this species showed the highest litterfall of leaves and stipules in summer and the lowest litterfall in winter. From Kendall＇s coefficient of concordance, the monthly changes in leaf, stipule, and branch were strongly and significantly concordant among years. Leaf and stipule litterfall could be governed by monthly maximum wind speed, monthly day length, and monthly mean air temperature. Branch litterfall depended on monthly maximum wind speed and monthly rainfall, and increased exponentially with increasing monthly maximum wind speed. Mean total litterfall was 11.8 Mg ha^（-1）yr^（-1）, with the largest component being leaf litterfall（65.8 %）. Annual leaf litterfall per plot was almost constant regardless of the tree density of the plot. Mean leaf longevity was 18 months.Flower and mature propagule litterfall might be influenced by monthly mean air temperature, monthly day length and monthly mean air temperature. The average development periods from flower buds to flowers and flower buds to mature propagules were 1 and 8 months, respectively.Except for leaf and branch, all vegetative and reproductive organ litterfall had clear annual cycles. B. gymnorrhiza showed a positive correlation between leaf production and reproductive organ production.展开更多
Recycled polystyrene in combination with paraffin wax,alkyd resin,and gum rosin were used as components in formulations to investigate their water repellency when applied to cellulosic filter paper substrates.Polystyr...Recycled polystyrene in combination with paraffin wax,alkyd resin,and gum rosin were used as components in formulations to investigate their water repellency when applied to cellulosic filter paper substrates.Polystyrene was used in concentration of 5,10,15 and 20%,alkyd resin and gum rosin of 5%each and paraffin wax of 0.5%.Totally,twenty four water repellent solutions were prepared.Water repellency was evaluated in terms of water absorption of the cellulosic fibrous mats.The relations between retention of solid substances of the formulations and grammage and water absorption of filter paper samples were also determined.The results showed that all the water repellent formulations exhibited a degree of water repellency.Water absorption decreased by increasing the polystyrene concentration in the solution and polystyrene retention by the impregnated filter paper samples.The incorporation of 0.5%paraffin wax improved the hydrophobicity of treated samples.The best of the three water repellent formulations including paraffin wax was found to be the“polystyrene+gum rosin+paraffin wax”solution followed by the“polystyrene+alkyd resin+paraffin wax”and“polystyrene+paraffin wax”solution.The inclusion of 5%gum rosin in polystyrene solutions compared to that of 0.5%paraffin wax was found more effective in almost all cases.展开更多
We studied the damage caused to unfelled trees during skidding operations in four beech stands of northern and central Greece that were managed under differing harvesting systems.After timber was harvested we recorded...We studied the damage caused to unfelled trees during skidding operations in four beech stands of northern and central Greece that were managed under differing harvesting systems.After timber was harvested we recorded and analyzed all damage to a width of 2 m along both sides of the skid trails.The percentage of damaged residual trees was 17–28 %.Higher numbers of saplings were uprooted or destroyed in parts of the stands with high natural regeneration.Most damaged trees suffered 1.33–1.90 wounds that were inflicted up to a height of 1 m above ground level.At all sites mean wound sizes were large,89–1190 cm2,and caused elevated risk of future fungal infection.The damage caused by skidding during timber harvesting can be minimized by better planning the harvest operations,and training forest workers in reduced impact logging.展开更多
Wood transportation begins from the landing or the forest road where the processed wood assortments are placed, they are loaded on trucks and then transported to the wood-working industry and/or the consumption center...Wood transportation begins from the landing or the forest road where the processed wood assortments are placed, they are loaded on trucks and then transported to the wood-working industry and/or the consumption centers. Wood transportation in Greece is carried out, almost exclusively, by trucks. The aim of this study is to analyze the evolution of timber trucking in Greece through the analysis of wood transportation waybills. A total of 1,471 waybills have been collected and analyzed that cover the period 1981-2008 from nine of the most productive and representative forest districts in Greece, in terms of timber production. The final dataset included information on the type and technical characteristics of truck types, the transported wood quantities and haulage distances. Furthermore, data on the wood transportation cost for the year 2010 have been collected and analyzed. According to the results, the number of two-axle trucks that dominated in the 1980s is reducing rapidly, mostly to the benefit of larger three-axle and four-axle trucks. More than three quarters （77%） of wood transportation is conducted in the period June-October. Mean vehicle load per vehicle type differs between conifer and broadleaved species from 7.1% up to 23.9%. Transportation of stacked wood with semitrailers is conducted with overloaded trucks, which could entail serious problems for public safety and the condition of road network. New design standards will enhance serviceability of the wood transportation routes and environmental protection.展开更多
基金supported by a Grant-in-Aid for Scientific Research(No.23380094)from the Ministry of Education,Culture,Sport,Science and Technology,Japan
文摘We evaluated the phenology and litterfall dynamics of the mangrove Bruguiera gymnorrhiza（L.）Lamk along the Okukubi River, Okinawa Island, Japan.Over 3 years, this species showed the highest litterfall of leaves and stipules in summer and the lowest litterfall in winter. From Kendall＇s coefficient of concordance, the monthly changes in leaf, stipule, and branch were strongly and significantly concordant among years. Leaf and stipule litterfall could be governed by monthly maximum wind speed, monthly day length, and monthly mean air temperature. Branch litterfall depended on monthly maximum wind speed and monthly rainfall, and increased exponentially with increasing monthly maximum wind speed. Mean total litterfall was 11.8 Mg ha^（-1）yr^（-1）, with the largest component being leaf litterfall（65.8 %）. Annual leaf litterfall per plot was almost constant regardless of the tree density of the plot. Mean leaf longevity was 18 months.Flower and mature propagule litterfall might be influenced by monthly mean air temperature, monthly day length and monthly mean air temperature. The average development periods from flower buds to flowers and flower buds to mature propagules were 1 and 8 months, respectively.Except for leaf and branch, all vegetative and reproductive organ litterfall had clear annual cycles. B. gymnorrhiza showed a positive correlation between leaf production and reproductive organ production.
基金Financial support has been provided by the Swedish Research Council Formas(Project Grant No.942-2016-2,2017-21).
文摘Recycled polystyrene in combination with paraffin wax,alkyd resin,and gum rosin were used as components in formulations to investigate their water repellency when applied to cellulosic filter paper substrates.Polystyrene was used in concentration of 5,10,15 and 20%,alkyd resin and gum rosin of 5%each and paraffin wax of 0.5%.Totally,twenty four water repellent solutions were prepared.Water repellency was evaluated in terms of water absorption of the cellulosic fibrous mats.The relations between retention of solid substances of the formulations and grammage and water absorption of filter paper samples were also determined.The results showed that all the water repellent formulations exhibited a degree of water repellency.Water absorption decreased by increasing the polystyrene concentration in the solution and polystyrene retention by the impregnated filter paper samples.The incorporation of 0.5%paraffin wax improved the hydrophobicity of treated samples.The best of the three water repellent formulations including paraffin wax was found to be the“polystyrene+gum rosin+paraffin wax”solution followed by the“polystyrene+alkyd resin+paraffin wax”and“polystyrene+paraffin wax”solution.The inclusion of 5%gum rosin in polystyrene solutions compared to that of 0.5%paraffin wax was found more effective in almost all cases.
文摘We studied the damage caused to unfelled trees during skidding operations in four beech stands of northern and central Greece that were managed under differing harvesting systems.After timber was harvested we recorded and analyzed all damage to a width of 2 m along both sides of the skid trails.The percentage of damaged residual trees was 17–28 %.Higher numbers of saplings were uprooted or destroyed in parts of the stands with high natural regeneration.Most damaged trees suffered 1.33–1.90 wounds that were inflicted up to a height of 1 m above ground level.At all sites mean wound sizes were large,89–1190 cm2,and caused elevated risk of future fungal infection.The damage caused by skidding during timber harvesting can be minimized by better planning the harvest operations,and training forest workers in reduced impact logging.
文摘Wood transportation begins from the landing or the forest road where the processed wood assortments are placed, they are loaded on trucks and then transported to the wood-working industry and/or the consumption centers. Wood transportation in Greece is carried out, almost exclusively, by trucks. The aim of this study is to analyze the evolution of timber trucking in Greece through the analysis of wood transportation waybills. A total of 1,471 waybills have been collected and analyzed that cover the period 1981-2008 from nine of the most productive and representative forest districts in Greece, in terms of timber production. The final dataset included information on the type and technical characteristics of truck types, the transported wood quantities and haulage distances. Furthermore, data on the wood transportation cost for the year 2010 have been collected and analyzed. According to the results, the number of two-axle trucks that dominated in the 1980s is reducing rapidly, mostly to the benefit of larger three-axle and four-axle trucks. More than three quarters （77%） of wood transportation is conducted in the period June-October. Mean vehicle load per vehicle type differs between conifer and broadleaved species from 7.1% up to 23.9%. Transportation of stacked wood with semitrailers is conducted with overloaded trucks, which could entail serious problems for public safety and the condition of road network. New design standards will enhance serviceability of the wood transportation routes and environmental protection.
