Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We inv...Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We investigated the characteristics of biomass, litterfall and nutrient fluxes in the 8, 14 and 24 year-old stands, representing the young, middle-aged and mature stands. The results showed that Chinese fir plantations in central Fujian province had high productivity, and the proportion of stem mass in total biomass was between 50%-70%. Chinese fir was low nutrient-return tree species with litterfall. Nutrient withdrawal from senescing needles was a strong age-dependence for nitrogen, phosphorous and potassium in Chinese fir. With a management system of such short-rotation and continuously pure-crop planting, harvesting timber can lead to great nutrient loss, which may be one of the causes for site degradation.展开更多
Black locust (Robinia pseudoacacia L.) was the first forest tree species to be imported from North America to Europe at the beginning of the 17th century. It is the most important fast-growing stand-forming tree speci...Black locust (Robinia pseudoacacia L.) was the first forest tree species to be imported from North America to Europe at the beginning of the 17th century. It is the most important fast-growing stand-forming tree species in Hungary. Black locust planta-tions can be successfully established in response to a range of economic and ecological opportunities. Plantation survival and productivity are maximized by matching the species' growth characteristics with silvicultural options and land management needs. In the paper the sequence of forest tending operations in black locust stands is proposed, based on results of long-term stand structure and forest yield trials. Implementing good silvicultural plans and models will lead to profitable black locust stands and greater ac-ceptance of the species by land managers. Black locust would also be a very useful species for energy productions as the related research results have been shown in the paper.展开更多
The paper deals with the stand structure and yield of black locust (Robinia pseudoacacia L.) forests mixed with white (Populus alba L.) in various proportions, partly applying a new methodological approach. The main s...The paper deals with the stand structure and yield of black locust (Robinia pseudoacacia L.) forests mixed with white (Populus alba L.) in various proportions, partly applying a new methodological approach. The main stand structure and yield factors were determined separately for each species, measured stem by stem, using the volume functions prepared for each species. The ratio of the volumes of the species (A and B) in mixed and in pure stands (based on volume tables) was determined. A close relationship has been found between the ratio by relative total volume and the proportion (by the number of stems) of the species. The relative surplus in the volume of the mixed stands varied between 1.24-1.55 at the age of 16 compared to the control, i.e. the yield of pure stands of the species concerned. The trial has also proven that if two species have a fast initial growth rate and a similar rotation age, they can be planted in mixed stands resulting in mutual advantages.展开更多
The impacts of mechanised forest harvesting to soil physical properties are the major concern by forest managers, which have the potential to impact soil sustainability and forest productivity. Malaysia is practicing ...The impacts of mechanised forest harvesting to soil physical properties are the major concern by forest managers, which have the potential to impact soil sustainability and forest productivity. Malaysia is practicing reduce impact logging （RIL） and applying code of forest harvest practice in forest harvesting and operations for sustainable forest resources management. In 2001, a machinery called Rimbaka Timber Harvester R2020-A was introduced for timber extraction for peat swamp forest and later on the machine was introduced to the hill tropical forest as an alternative to other machines. The study aimed to evaluate soil compaction （soil cone index, soil bulk density, soil moisture content and soil pore space） by Rimbaka Timber Harvester R2020-A and crawler tractor KOMATSU D60-A. A total of five samples were randomly taken using core sampler of 50 mm height and 50 mm diameter at the beneath a lug imprint for passes 1, 4 and 8. Altogether samples were 45. The locations of sample were to the fight and left of each rut centre for both machines. Treatment effects were evaluated using analysis of variance （ANOVA）. Result showed that compaction by Rimbaka machine was increased bulk density from 1.14 to 1.43 g/cc, cone index from 1.94 to 3.45 g/cm3 decreased total pore space by 43% and decreased soil moisture content by 19%. Meanwhile compaction by KOMATSU D60-A was increased bulk density from 1.2 to 1.43 g/co, cone index from 1.24 to 1.94 g/cm3 decreased soil moisture content by 11% and total pore space by 6%, respectively. The value increased rapidly as more passes increase on the track surface. The higher soil disturbance by Rimbaka machine was due to physical design and specification of the machine. This study also observed that there was significant difference in the total passes of machinery used in harvesting operation. Although Rimbaka machine is showing more effected to soil compaction, the machine is a practical alternative to avoid skid trail and reduce road density in forest area.展开更多
基金This research was sponsored by National Natural Science Foundation of China (Grant No. 39630240 and 3000132).
文摘Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We investigated the characteristics of biomass, litterfall and nutrient fluxes in the 8, 14 and 24 year-old stands, representing the young, middle-aged and mature stands. The results showed that Chinese fir plantations in central Fujian province had high productivity, and the proportion of stem mass in total biomass was between 50%-70%. Chinese fir was low nutrient-return tree species with litterfall. Nutrient withdrawal from senescing needles was a strong age-dependence for nitrogen, phosphorous and potassium in Chinese fir. With a management system of such short-rotation and continuously pure-crop planting, harvesting timber can lead to great nutrient loss, which may be one of the causes for site degradation.
文摘Black locust (Robinia pseudoacacia L.) was the first forest tree species to be imported from North America to Europe at the beginning of the 17th century. It is the most important fast-growing stand-forming tree species in Hungary. Black locust planta-tions can be successfully established in response to a range of economic and ecological opportunities. Plantation survival and productivity are maximized by matching the species' growth characteristics with silvicultural options and land management needs. In the paper the sequence of forest tending operations in black locust stands is proposed, based on results of long-term stand structure and forest yield trials. Implementing good silvicultural plans and models will lead to profitable black locust stands and greater ac-ceptance of the species by land managers. Black locust would also be a very useful species for energy productions as the related research results have been shown in the paper.
基金Part of the work was financed by OTKA support(Ref.No.T 029021)
文摘The paper deals with the stand structure and yield of black locust (Robinia pseudoacacia L.) forests mixed with white (Populus alba L.) in various proportions, partly applying a new methodological approach. The main stand structure and yield factors were determined separately for each species, measured stem by stem, using the volume functions prepared for each species. The ratio of the volumes of the species (A and B) in mixed and in pure stands (based on volume tables) was determined. A close relationship has been found between the ratio by relative total volume and the proportion (by the number of stems) of the species. The relative surplus in the volume of the mixed stands varied between 1.24-1.55 at the age of 16 compared to the control, i.e. the yield of pure stands of the species concerned. The trial has also proven that if two species have a fast initial growth rate and a similar rotation age, they can be planted in mixed stands resulting in mutual advantages.
文摘The impacts of mechanised forest harvesting to soil physical properties are the major concern by forest managers, which have the potential to impact soil sustainability and forest productivity. Malaysia is practicing reduce impact logging （RIL） and applying code of forest harvest practice in forest harvesting and operations for sustainable forest resources management. In 2001, a machinery called Rimbaka Timber Harvester R2020-A was introduced for timber extraction for peat swamp forest and later on the machine was introduced to the hill tropical forest as an alternative to other machines. The study aimed to evaluate soil compaction （soil cone index, soil bulk density, soil moisture content and soil pore space） by Rimbaka Timber Harvester R2020-A and crawler tractor KOMATSU D60-A. A total of five samples were randomly taken using core sampler of 50 mm height and 50 mm diameter at the beneath a lug imprint for passes 1, 4 and 8. Altogether samples were 45. The locations of sample were to the fight and left of each rut centre for both machines. Treatment effects were evaluated using analysis of variance （ANOVA）. Result showed that compaction by Rimbaka machine was increased bulk density from 1.14 to 1.43 g/cc, cone index from 1.94 to 3.45 g/cm3 decreased total pore space by 43% and decreased soil moisture content by 19%. Meanwhile compaction by KOMATSU D60-A was increased bulk density from 1.2 to 1.43 g/co, cone index from 1.24 to 1.94 g/cm3 decreased soil moisture content by 11% and total pore space by 6%, respectively. The value increased rapidly as more passes increase on the track surface. The higher soil disturbance by Rimbaka machine was due to physical design and specification of the machine. This study also observed that there was significant difference in the total passes of machinery used in harvesting operation. Although Rimbaka machine is showing more effected to soil compaction, the machine is a practical alternative to avoid skid trail and reduce road density in forest area.
