The concentrations of the foliar and surface soil nutrients and the variation with species and stand age were studied inPinus spp. plantations in Zhanggutai area, northeast China. The results showed that the total N, ...The concentrations of the foliar and surface soil nutrients and the variation with species and stand age were studied inPinus spp. plantations in Zhanggutai area, northeast China. The results showed that the total N, total P and C: N ratio of the soil inP. sylvestris var.mongolica stands were significantly higher in comparison with those inP. tabulaeformis andP. densiflora stands. ForP. sylvestris var.mongolica, the foliar P concentration appeared to decrease with age, and the foliar N and K concentrations did not show a consistent change with age. As for the different tree species of the similar age, the foliar N and P concentrations were significantly different (p<0.05), being withP. sylvestris var.mongolica>P. densiflora>P. tabulaeformis. The foliar N: P ratio ofP. densiflora significantly was higher thanP. sylvestris var.mongolica andP. tabulaeformis, while the foliar K was no obvious difference between the three tree species. There were significant correlation (p<0.05) between soil total N and P, soil organic matter and total P, foliar N and P, but it did not show significant correlations between soil and foliar nutrient concentrations, which might attribute to the excessive litter raking, overgrazing and low soil moisture in this area. Based on the foliar N: P ratio, we introduced a combination threshold index of N: P ratio with their absolute foliar nutrient concentrations to determine the possible limiting nutrient. According to the critical N: P ratio and their absolute foliar N, P concentrations, theP. sylvestris var.mongolica stands showed a decreased N limitation degree with age, theP. densiflora stands showed unlimited by N and P in the whole, and theP. tabulaeformis stands showed co-limited by N and P. No significant difference in soil nutrient concentrations of the surface soils was found between 45, 29, 20-yr-oldPinus sylvestris var.mongolica plantation stands. Keywords coniferous trees - foliar nutrient concentration - limiting nutrients - N - P ratio - Zhanggutai sandy land CLC number S718.55 Document code A Article ID 1007-662X(2004)01-0011-08 Foundation item: This research was supported by Key Knowledge Innovation Project (KZCX3-SW-418) of Chinese Academy of Sciences.Biography: CHEN Guang-sheng (1978-), male, master candidate in Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. ChinaResponsible editor: Song Funan展开更多
In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris v...In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris var. mongolica trees from two provenances （natural forests and plantations）. The results indicated that natural tree needles had lower N, P and C concentrations, and higher K concentrations than those of plantation tree needles. For plantation tree needles, ratios of N： P, P. K and N： K increased with tree age before 45 years old; but they were not clear for the natural tree needles. Compared with the conclusions reported on Pinus spp., we found that the foliar N and P concentrations were in the optimal range for both natural and plantation tree needles. This result suggested that N or P might not be the absolute limit factors in plant nutrient for P sylvestris var. mongolica on sandy land. However, foliar K concentrations in both natural and plantation tree needles were much lower than those reported on Pinus spp. （〉4.80 g kg-1）.The N： P ratio of natural needles was in the adequate ranges, but N： P ratio of plantation needles was out of the adequate ranges. These results indicated that there was a better balanced nutrition status in the natural forest than in the plantations. If only considering the foliar nutrient concentrations of P sylvestris var. mongolica from different provenances, it might be concluded that the degradation phenomenon of P. sylvestris var. mongolica plantations was not induced by nutrition deficiency of absolute nutrients of N and P, but might be induced by other mineral nutrients or by the effectiveness of N and P nutrients. The unbalanced nutrition status and relatively quick decomposition of needles in the plantations might also contribute to the degradation.展开更多
The neutron yield in the12C(d,n)13N reaction and the proton yield in the12C(d,p)13C reaction have been measured using deuteron beams of energies 0.6-3 MeV.The deuteron beam is delivered from a 4-MeV electrostatic acce...The neutron yield in the12C(d,n)13N reaction and the proton yield in the12C(d,p)13C reaction have been measured using deuteron beams of energies 0.6-3 MeV.The deuteron beam is delivered from a 4-MeV electrostatic accelerator and bombarded on a thick carbon target.The neutrons are detected at 0°,24°,and 48°and the protons at135°in the laboratory frame.Further,the ratio of the neutron yield to the proton yield was calculated.This can be used to effectively recognize the resonances.The resonances are found at 1.4 MeV,1.7 MeV,and 2.5 MeV in the12C(d,p)13C reaction,and at 1.6 MeV and 2.7 MeV in the12C(d,n)13N reaction.The proposed method provides a way to reduce systematic uncertainty and helps confirm more resonances in compound nuclei.展开更多
Background:Carbon(C),nitrogen(N),and phosphorus(P)stoichiometry is a key indicator of nutrient utilization in plants,and C/N/P ratios are related to the life histories and adaptation strategies of tree species.However...Background:Carbon(C),nitrogen(N),and phosphorus(P)stoichiometry is a key indicator of nutrient utilization in plants,and C/N/P ratios are related to the life histories and adaptation strategies of tree species.However,no consensus has been reached on how leaf stoichiometric characteristics are affected by forest type and stand ages.The relationships between leaf stoichiometry and geographical,meteorological,and soil factors also remain poorly understood.Methods:Leaf and soil were sampled from forest stands of different age groups(young,middle-aged,near-mature,and mature)in two forest types(Chinese fir(Cunninghamia lanceolata)forests and evergreen broadleaved forests).The relationships between leaf C,N,and P stoichiometric parameters and geographical,meteorological,and soil factors were analysed by using redundancy analysis(RDA)and stepwise linear regression analysis.Results:Leaf C concentrations peaked in the near-mature stands with increasing age irrespective of forest type.Leaf N and P concentrations fluctuated with a rising trend in Chinese fir forests,while decreased first and increased later from young to mature phases in natural evergreen broadleaved forests.Chinese fir forests were primarily limited by N and P,while natural evergreen broadleaved forests were more susceptible to P limitation.Leaf C,N,and P stoichiometric characteristics in Chinese fir forests were mainly affected by the soil total P concentration(SP),longitude(LNG),growing season precipitation(GSP)and mean temperature in July(JUT).The leaf C concentration was mainly affected by GSP and JUT;leaf N and P concentrations were both positively correlated with LNG;and leaf P was positively correlated with SP.In evergreen broadleaved forests,however,leaf stoichiometric parameters displayed significant correlations with latitude(LAT)and mean annual precipitation(MAP).Conclusions:Leaf stoichiometry differed among forest stands of different age groups and forest types.Leaf C,N,and P stoichiometry was primarily explained by the combinations of SP,LNG,GSP and JUT in Chinese fir forests.LAT and MAP were the main controlling factors affecting the variations in the leaf C,N,and P status in natural evergreen broadleaved forests,which supports the temperature-plant physiological hypothesis.These findings improve the understanding of the distribution patterns and driving mechanisms of leaf stoichiometry linked with stand age and forest type.展开更多
基金Key Knowledge Innovation Project (KZCX3-SW-418) of Chinese Academy of Sciences.
文摘The concentrations of the foliar and surface soil nutrients and the variation with species and stand age were studied inPinus spp. plantations in Zhanggutai area, northeast China. The results showed that the total N, total P and C: N ratio of the soil inP. sylvestris var.mongolica stands were significantly higher in comparison with those inP. tabulaeformis andP. densiflora stands. ForP. sylvestris var.mongolica, the foliar P concentration appeared to decrease with age, and the foliar N and K concentrations did not show a consistent change with age. As for the different tree species of the similar age, the foliar N and P concentrations were significantly different (p<0.05), being withP. sylvestris var.mongolica>P. densiflora>P. tabulaeformis. The foliar N: P ratio ofP. densiflora significantly was higher thanP. sylvestris var.mongolica andP. tabulaeformis, while the foliar K was no obvious difference between the three tree species. There were significant correlation (p<0.05) between soil total N and P, soil organic matter and total P, foliar N and P, but it did not show significant correlations between soil and foliar nutrient concentrations, which might attribute to the excessive litter raking, overgrazing and low soil moisture in this area. Based on the foliar N: P ratio, we introduced a combination threshold index of N: P ratio with their absolute foliar nutrient concentrations to determine the possible limiting nutrient. According to the critical N: P ratio and their absolute foliar N, P concentrations, theP. sylvestris var.mongolica stands showed a decreased N limitation degree with age, theP. densiflora stands showed unlimited by N and P in the whole, and theP. tabulaeformis stands showed co-limited by N and P. No significant difference in soil nutrient concentrations of the surface soils was found between 45, 29, 20-yr-oldPinus sylvestris var.mongolica plantation stands. Keywords coniferous trees - foliar nutrient concentration - limiting nutrients - N - P ratio - Zhanggutai sandy land CLC number S718.55 Document code A Article ID 1007-662X(2004)01-0011-08 Foundation item: This research was supported by Key Knowledge Innovation Project (KZCX3-SW-418) of Chinese Academy of Sciences.Biography: CHEN Guang-sheng (1978-), male, master candidate in Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. ChinaResponsible editor: Song Funan
基金The research was supported by Innovation Research Project of Chinese Academy of Sciences (KZCX3-SW-418), and the 100 Young Researcher Project of Chinese Academy of Sciences.
文摘In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris var. mongolica trees from two provenances （natural forests and plantations）. The results indicated that natural tree needles had lower N, P and C concentrations, and higher K concentrations than those of plantation tree needles. For plantation tree needles, ratios of N： P, P. K and N： K increased with tree age before 45 years old; but they were not clear for the natural tree needles. Compared with the conclusions reported on Pinus spp., we found that the foliar N and P concentrations were in the optimal range for both natural and plantation tree needles. This result suggested that N or P might not be the absolute limit factors in plant nutrient for P sylvestris var. mongolica on sandy land. However, foliar K concentrations in both natural and plantation tree needles were much lower than those reported on Pinus spp. （〉4.80 g kg-1）.The N： P ratio of natural needles was in the adequate ranges, but N： P ratio of plantation needles was out of the adequate ranges. These results indicated that there was a better balanced nutrition status in the natural forest than in the plantations. If only considering the foliar nutrient concentrations of P sylvestris var. mongolica from different provenances, it might be concluded that the degradation phenomenon of P. sylvestris var. mongolica plantations was not induced by nutrition deficiency of absolute nutrients of N and P, but might be induced by other mineral nutrients or by the effectiveness of N and P nutrients. The unbalanced nutrition status and relatively quick decomposition of needles in the plantations might also contribute to the degradation.
基金partially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDB16 and XDPB09)the National Natural Science Foundation of China(Nos.11890714 and 11421505)the Key Research Program of Frontier Sciences of the CAS(No.QYZDJ-SSW-SLH002)
文摘The neutron yield in the12C(d,n)13N reaction and the proton yield in the12C(d,p)13C reaction have been measured using deuteron beams of energies 0.6-3 MeV.The deuteron beam is delivered from a 4-MeV electrostatic accelerator and bombarded on a thick carbon target.The neutrons are detected at 0°,24°,and 48°and the protons at135°in the laboratory frame.Further,the ratio of the neutron yield to the proton yield was calculated.This can be used to effectively recognize the resonances.The resonances are found at 1.4 MeV,1.7 MeV,and 2.5 MeV in the12C(d,p)13C reaction,and at 1.6 MeV and 2.7 MeV in the12C(d,n)13N reaction.The proposed method provides a way to reduce systematic uncertainty and helps confirm more resonances in compound nuclei.
基金supported by the National Natural Science Foundation of China(No.31971643)the Industry-University Cooperation Project of Fujian Science and Technology Department(Nos.2020N5008,2019N5009)+2 种基金the General program of Natural Science Foundation of Fujian Province of China(No.2018J01737)Special Funding Project of Fujian Provincial Department of Finance(SC-299)Minjiang Scholar Programme.
文摘Background:Carbon(C),nitrogen(N),and phosphorus(P)stoichiometry is a key indicator of nutrient utilization in plants,and C/N/P ratios are related to the life histories and adaptation strategies of tree species.However,no consensus has been reached on how leaf stoichiometric characteristics are affected by forest type and stand ages.The relationships between leaf stoichiometry and geographical,meteorological,and soil factors also remain poorly understood.Methods:Leaf and soil were sampled from forest stands of different age groups(young,middle-aged,near-mature,and mature)in two forest types(Chinese fir(Cunninghamia lanceolata)forests and evergreen broadleaved forests).The relationships between leaf C,N,and P stoichiometric parameters and geographical,meteorological,and soil factors were analysed by using redundancy analysis(RDA)and stepwise linear regression analysis.Results:Leaf C concentrations peaked in the near-mature stands with increasing age irrespective of forest type.Leaf N and P concentrations fluctuated with a rising trend in Chinese fir forests,while decreased first and increased later from young to mature phases in natural evergreen broadleaved forests.Chinese fir forests were primarily limited by N and P,while natural evergreen broadleaved forests were more susceptible to P limitation.Leaf C,N,and P stoichiometric characteristics in Chinese fir forests were mainly affected by the soil total P concentration(SP),longitude(LNG),growing season precipitation(GSP)and mean temperature in July(JUT).The leaf C concentration was mainly affected by GSP and JUT;leaf N and P concentrations were both positively correlated with LNG;and leaf P was positively correlated with SP.In evergreen broadleaved forests,however,leaf stoichiometric parameters displayed significant correlations with latitude(LAT)and mean annual precipitation(MAP).Conclusions:Leaf stoichiometry differed among forest stands of different age groups and forest types.Leaf C,N,and P stoichiometry was primarily explained by the combinations of SP,LNG,GSP and JUT in Chinese fir forests.LAT and MAP were the main controlling factors affecting the variations in the leaf C,N,and P status in natural evergreen broadleaved forests,which supports the temperature-plant physiological hypothesis.These findings improve the understanding of the distribution patterns and driving mechanisms of leaf stoichiometry linked with stand age and forest type.
