Allelopathic effect of larch (Larix gmelini ) on the ash growth (Fraximus mandshurica) was studied in artificial cultivation tests. The results revealed that the larch root secretion obviously stimulated the ash growt...Allelopathic effect of larch (Larix gmelini ) on the ash growth (Fraximus mandshurica) was studied in artificial cultivation tests. The results revealed that the larch root secretion obviously stimulated the ash growth. In order to determine the main stimulation allelochemicals, the chemical composition was analyzed. By contrasting the contents of carbohydrate and aminoacid in root secretion of larch and ash, it was concluded that the carbohydrate and aminoacid were not important stimulation allelochemicals. The organic acid and other components in root secration of larch and ash were analyzed by GC and GC-MS analysis. The sand culture tests were carried out ed selected model compounds. The results showed that benzeneacetic acid, benzenepropionic acid and phenolic acids in root secretion of larch were the main stimulation allelochemicals.展开更多
Permanent sample plots were set up for researching interspecific relationship of the artificia1 larch stand mixed with natural ash in the slash site in Maoershan Experiment Forestry Farm of Northeast Forestry Universi...Permanent sample plots were set up for researching interspecific relationship of the artificia1 larch stand mixed with natural ash in the slash site in Maoershan Experiment Forestry Farm of Northeast Forestry University. All trees in the plots were taken as objective trees and tree number,DBH, distance between trees and that of crown diameter were measured in range of 1-6m from every objective tree. Then study by Alemdag competition index, variance analysis and quantitation method were made. The result showed that the intraspecific competition was more intensive than the interspecific competition. Especially the competition between larch and ash was least relatively. For these kinds of site, the suitable mixture at 20-30 ages should be 2800 Ind/hm2 in density and 2 larch;1 ash in mixed ratio, which might improve site condition to promote stand produetivity.展开更多
With the method of stem analyses by the microscope, the xylem’s accumulations atdifferent ages were quantitatively studied using the data of typical plant association for Dahurianlarch (Larix gmelini Rupr) and Manchu...With the method of stem analyses by the microscope, the xylem’s accumulations atdifferent ages were quantitatively studied using the data of typical plant association for Dahurianlarch (Larix gmelini Rupr) and Manchurian ash (Fraxinus mandshurica Rupr) mixed forests. Thedeveloping process for this important mixed forest type in the study area was systematically established. The result showed that in the artificial stand of Dahurian larch mixed with naturalManchurian ash. only those which have the same origin as Dahurian larch can grow up before theclosing of stand and form the components of the main layers. After 24 years seif-thinning, when theywere 29 years old, Dahurian larch would be at the stage of no self-thinning. At last the stand woulddevelop to the broad-leaved forests dominating with the Manchurian ash.展开更多
According to the study on soils under the 34-year-old Larch forest and Larch-Walnut mixed forest. It tvas concluded that, in mixed forest, the total content of water- stable aggregate (0. 25- 5mm) in the upper layers ...According to the study on soils under the 34-year-old Larch forest and Larch-Walnut mixed forest. It tvas concluded that, in mixed forest, the total content of water- stable aggregate (0. 25- 5mm) in the upper layers (0- 30cm) of soil was significant ly higher than that in pure forest. The 2mm aggregates increased 48% in mixed forest soil compared with pure fOrest. and consequently, the three-phase ratio of soil was regulate d, the physical properties improved and the fertility of soil raised. Because of the stability of total aggregate content and the importance of 2mm aggregate content in soil fertility.it s advisable using the two indices above to characterize the effect of mixed forest on soil improvement.展开更多
Allelopathic effect of larch (Larix gmelini) leaching on ash (Fraxinus mandshurica) growth was studied with sand culture test. It was understood that the ash growth was stimulated by the larch leaching. The chemical c...Allelopathic effect of larch (Larix gmelini) leaching on ash (Fraxinus mandshurica) growth was studied with sand culture test. It was understood that the ash growth was stimulated by the larch leaching. The chemical compositions of the larch and ash leaching were identified and determined by chemical and instrumental analysis. The results showed that in the larch and ash leaching there were fatty acids (including monocarboxylic, dicarboxylic and tricarboxylic acids), phenolic acids, tannin, aromatic alcohols, polylol, aminoacids and carbohydrate, etc. on the basis of the analytical results of chemical composition, with reference to the results of model compound test, it is considered that the citric acid in the larch leaching was the main simulative allelochemical to the ash growth, and trihydroxybenzeneacetic acid was the subordinate stimulative allelochemical.展开更多
文摘Allelopathic effect of larch (Larix gmelini ) on the ash growth (Fraximus mandshurica) was studied in artificial cultivation tests. The results revealed that the larch root secretion obviously stimulated the ash growth. In order to determine the main stimulation allelochemicals, the chemical composition was analyzed. By contrasting the contents of carbohydrate and aminoacid in root secretion of larch and ash, it was concluded that the carbohydrate and aminoacid were not important stimulation allelochemicals. The organic acid and other components in root secration of larch and ash were analyzed by GC and GC-MS analysis. The sand culture tests were carried out ed selected model compounds. The results showed that benzeneacetic acid, benzenepropionic acid and phenolic acids in root secretion of larch were the main stimulation allelochemicals.
文摘Permanent sample plots were set up for researching interspecific relationship of the artificia1 larch stand mixed with natural ash in the slash site in Maoershan Experiment Forestry Farm of Northeast Forestry University. All trees in the plots were taken as objective trees and tree number,DBH, distance between trees and that of crown diameter were measured in range of 1-6m from every objective tree. Then study by Alemdag competition index, variance analysis and quantitation method were made. The result showed that the intraspecific competition was more intensive than the interspecific competition. Especially the competition between larch and ash was least relatively. For these kinds of site, the suitable mixture at 20-30 ages should be 2800 Ind/hm2 in density and 2 larch;1 ash in mixed ratio, which might improve site condition to promote stand produetivity.
文摘With the method of stem analyses by the microscope, the xylem’s accumulations atdifferent ages were quantitatively studied using the data of typical plant association for Dahurianlarch (Larix gmelini Rupr) and Manchurian ash (Fraxinus mandshurica Rupr) mixed forests. Thedeveloping process for this important mixed forest type in the study area was systematically established. The result showed that in the artificial stand of Dahurian larch mixed with naturalManchurian ash. only those which have the same origin as Dahurian larch can grow up before theclosing of stand and form the components of the main layers. After 24 years seif-thinning, when theywere 29 years old, Dahurian larch would be at the stage of no self-thinning. At last the stand woulddevelop to the broad-leaved forests dominating with the Manchurian ash.
文摘According to the study on soils under the 34-year-old Larch forest and Larch-Walnut mixed forest. It tvas concluded that, in mixed forest, the total content of water- stable aggregate (0. 25- 5mm) in the upper layers (0- 30cm) of soil was significant ly higher than that in pure forest. The 2mm aggregates increased 48% in mixed forest soil compared with pure fOrest. and consequently, the three-phase ratio of soil was regulate d, the physical properties improved and the fertility of soil raised. Because of the stability of total aggregate content and the importance of 2mm aggregate content in soil fertility.it s advisable using the two indices above to characterize the effect of mixed forest on soil improvement.
文摘Allelopathic effect of larch (Larix gmelini) leaching on ash (Fraxinus mandshurica) growth was studied with sand culture test. It was understood that the ash growth was stimulated by the larch leaching. The chemical compositions of the larch and ash leaching were identified and determined by chemical and instrumental analysis. The results showed that in the larch and ash leaching there were fatty acids (including monocarboxylic, dicarboxylic and tricarboxylic acids), phenolic acids, tannin, aromatic alcohols, polylol, aminoacids and carbohydrate, etc. on the basis of the analytical results of chemical composition, with reference to the results of model compound test, it is considered that the citric acid in the larch leaching was the main simulative allelochemical to the ash growth, and trihydroxybenzeneacetic acid was the subordinate stimulative allelochemical.
