The cycling characteristics of nitrogen(N), phosphorus(P) and potassium(K) of the Quercus acutissima and Pinus massoniana mixed forest which is the most common forest type in the Three Gorge Reservoir areas in China,...The cycling characteristics of nitrogen(N), phosphorus(P) and potassium(K) of the Quercus acutissima and Pinus massoniana mixed forest which is the most common forest type in the Three Gorge Reservoir areas in China, were systematically analyzed. The results showed that N, P and K accumulated in the plant pool and in the litter pool, while total N, P, and K were deficient in the soil pool and in the forest systems. Contents of N in the soil of depth 20—40 cm were the key factor limiting growth of trees. The biological outside cycling coefficients were 878, 725 and 117 times of inside cycling coefficients of N, P and K, respectively. 3392, 1026 and 1588 kg of N, P and K return to the litter pool from branches, leaves and throughfall per year, but, 1431, 132 and 1048 kg of N, P and K return to the soil from litter pool per year respectively. It is clear that 58% of N, 87% of P, and 34% of K are lost by surface runoff per year. 549%, 130%, and 834% of N, P and K withdraw from leaves to branches, 499%, 199% and 730% of N, P and K withdraw from branches to trunks per year, respectively.展开更多
Phloem is the woody tissue for the storage and long-distance transport of organic matter in vascular bundles.To reveal the process of secondary phloem development and differentiation in Pinus massoniana,the structure ...Phloem is the woody tissue for the storage and long-distance transport of organic matter in vascular bundles.To reveal the process of secondary phloem development and differentiation in Pinus massoniana,the structure of the secondary phloem and the distribution of cell inclusions were observed by histochemical staining,spontaneous fluorescence of phenolic substances and cell segregation.Based on tissue development and differentiation characteristics of P.massoniana secondary phloem,the secondary phloem development was divided into seven stages:the functional phloem stage;the sieve cell lignification stage;the phloem ray bending stage;the parenchyma cell dedifferentiation and division stage;the dedifferentiated parenchyma cell population formation stage;the periderm alteration stage,and the rhytidome stage.An analysis of cell morphology and inclusion distribution characteristics showed that the sieve cells were deformed during lignification,the quantities of parenchyma and resin ducts increased with development and the crystal content in cells,as well as the levels of sugars and lipids in phloem parenchyma cells,increased with development.The results indicate that the P.massoniana phloem first lost longitudinal transport function and then increased its secretory,storage and mechanical functions.Ultimately,the parenchyma differentiated into the cortex and periderm,and the tissue outside the new periderm lignified to form the rhytidome,which fully developed into the protective tissue of the stem.展开更多
The runoff and runoff process of Eucalyptus plantations natural watershed were studied to provide guidance for scientific evaluation of water conservation capacities of Eucalyptus plantations,compared with the Pinus m...The runoff and runoff process of Eucalyptus plantations natural watershed were studied to provide guidance for scientific evaluation of water conservation capacities of Eucalyptus plantations,compared with the Pinus massoniana forest natural watershed. The runoff volumes of Eucalyptus plantations and P. massoniana forest natural watersheds were continuously monitored using the small watershed runoff monitoring method and the automatic data collection devices from August,2013 to December,2016,and effects of heavy rainfall and continuous rainfall on the runoff process were studied. Results showed that the annual runoff coefficient of Eucalyptus plantations natural watershed was 0. 050,and 55. 4% lower than P. massoniana forest（ 0. 112）,with the difference being significant（ P 〈 0. 01）. Total runoff duration,time of maximum runoff lagging behind rainfall peak,and runoff duration caused by a heavy rainfall process（ amounting to 147. 5 mm） between the two kinds of forest watersheds were significant different,those of Eucalyptus plantations were 35. 6 mm,0. 2 h and 13. 8 h,respectively,while those of P. massoniana forest were28. 5 mm,0. 7 h and 35. 5 h,respectively. Eucalyptus plantations natural watershed produced only 4-days runoff,and runoff depth amounted to3. 8 mm with a 7-days continuous precipitation process of rainfall with 125. 0 mm,while P. massoniana forest natural watershed produced continuously 13-days runoff,and the runoff depth was 10. 1 mm. In conclusion,water conservation capacity of Eucalyptus plantations is obviously lower than P. massoniana forest.展开更多
The objective of this study was to determine the pathogenicity of Bursapelenchus xylophilus isolates from China, Japan and Canada to 4-year black pine (Pinus thunbergii) and masson pine (Pinus massoniana) seedling. Th...The objective of this study was to determine the pathogenicity of Bursapelenchus xylophilus isolates from China, Japan and Canada to 4-year black pine (Pinus thunbergii) and masson pine (Pinus massoniana) seedling. The results showed that their pathogenicity diferentiated distinctly. The mortality of black pine ranged from 0 to 87.5%, and the RHS index ranged from 0 to 110. The pathogenicity of Chinese nematode populations was greater than that of Japan and Canada. The pathogenicity of BxCN3, BxCSC and BxCZD was stronger, with mortality 87.5% and the RHS index exceeding 90. In the 6 isolates whose dead rates were 87.5%, the population of BxCN3 from Nanjing had the shortest death time, 38 days. In all of the tested populatios, the dead process of population BxCZD from Zhejiang was shortest, 14 days in black pine. The results of detrermination in P. massoniana indicated that 4-year seedlings resisted P. xylophilus, with only two seedlings died in this experiment. In this study, incubating carrier with non-symptom was found in P. thunbergii seedlings inoculated with pine wood nematode. It is important for incubaton of nematodes of the spread of the nematode.展开更多
文摘The cycling characteristics of nitrogen(N), phosphorus(P) and potassium(K) of the Quercus acutissima and Pinus massoniana mixed forest which is the most common forest type in the Three Gorge Reservoir areas in China, were systematically analyzed. The results showed that N, P and K accumulated in the plant pool and in the litter pool, while total N, P, and K were deficient in the soil pool and in the forest systems. Contents of N in the soil of depth 20—40 cm were the key factor limiting growth of trees. The biological outside cycling coefficients were 878, 725 and 117 times of inside cycling coefficients of N, P and K, respectively. 3392, 1026 and 1588 kg of N, P and K return to the litter pool from branches, leaves and throughfall per year, but, 1431, 132 and 1048 kg of N, P and K return to the soil from litter pool per year respectively. It is clear that 58% of N, 87% of P, and 34% of K are lost by surface runoff per year. 549%, 130%, and 834% of N, P and K withdraw from leaves to branches, 499%, 199% and 730% of N, P and K withdraw from branches to trunks per year, respectively.
基金supported by the Guizhou provincial scientific and technological program 20185261。
文摘Phloem is the woody tissue for the storage and long-distance transport of organic matter in vascular bundles.To reveal the process of secondary phloem development and differentiation in Pinus massoniana,the structure of the secondary phloem and the distribution of cell inclusions were observed by histochemical staining,spontaneous fluorescence of phenolic substances and cell segregation.Based on tissue development and differentiation characteristics of P.massoniana secondary phloem,the secondary phloem development was divided into seven stages:the functional phloem stage;the sieve cell lignification stage;the phloem ray bending stage;the parenchyma cell dedifferentiation and division stage;the dedifferentiated parenchyma cell population formation stage;the periderm alteration stage,and the rhytidome stage.An analysis of cell morphology and inclusion distribution characteristics showed that the sieve cells were deformed during lignification,the quantities of parenchyma and resin ducts increased with development and the crystal content in cells,as well as the levels of sugars and lipids in phloem parenchyma cells,increased with development.The results indicate that the P.massoniana phloem first lost longitudinal transport function and then increased its secretory,storage and mechanical functions.Ultimately,the parenchyma differentiated into the cortex and periderm,and the tissue outside the new periderm lignified to form the rhytidome,which fully developed into the protective tissue of the stem.
基金Supported by Special Project for Scientific Research of Public Welfare Industry of Ministry of Water Resources(201301044)
文摘The runoff and runoff process of Eucalyptus plantations natural watershed were studied to provide guidance for scientific evaluation of water conservation capacities of Eucalyptus plantations,compared with the Pinus massoniana forest natural watershed. The runoff volumes of Eucalyptus plantations and P. massoniana forest natural watersheds were continuously monitored using the small watershed runoff monitoring method and the automatic data collection devices from August,2013 to December,2016,and effects of heavy rainfall and continuous rainfall on the runoff process were studied. Results showed that the annual runoff coefficient of Eucalyptus plantations natural watershed was 0. 050,and 55. 4% lower than P. massoniana forest（ 0. 112）,with the difference being significant（ P 〈 0. 01）. Total runoff duration,time of maximum runoff lagging behind rainfall peak,and runoff duration caused by a heavy rainfall process（ amounting to 147. 5 mm） between the two kinds of forest watersheds were significant different,those of Eucalyptus plantations were 35. 6 mm,0. 2 h and 13. 8 h,respectively,while those of P. massoniana forest were28. 5 mm,0. 7 h and 35. 5 h,respectively. Eucalyptus plantations natural watershed produced only 4-days runoff,and runoff depth amounted to3. 8 mm with a 7-days continuous precipitation process of rainfall with 125. 0 mm,while P. massoniana forest natural watershed produced continuously 13-days runoff,and the runoff depth was 10. 1 mm. In conclusion,water conservation capacity of Eucalyptus plantations is obviously lower than P. massoniana forest.
文摘The objective of this study was to determine the pathogenicity of Bursapelenchus xylophilus isolates from China, Japan and Canada to 4-year black pine (Pinus thunbergii) and masson pine (Pinus massoniana) seedling. The results showed that their pathogenicity diferentiated distinctly. The mortality of black pine ranged from 0 to 87.5%, and the RHS index ranged from 0 to 110. The pathogenicity of Chinese nematode populations was greater than that of Japan and Canada. The pathogenicity of BxCN3, BxCSC and BxCZD was stronger, with mortality 87.5% and the RHS index exceeding 90. In the 6 isolates whose dead rates were 87.5%, the population of BxCN3 from Nanjing had the shortest death time, 38 days. In all of the tested populatios, the dead process of population BxCZD from Zhejiang was shortest, 14 days in black pine. The results of detrermination in P. massoniana indicated that 4-year seedlings resisted P. xylophilus, with only two seedlings died in this experiment. In this study, incubating carrier with non-symptom was found in P. thunbergii seedlings inoculated with pine wood nematode. It is important for incubaton of nematodes of the spread of the nematode.
