Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two question...Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.展开更多
In order to investigate the effect of invastion by pine wood nematode(PWN), this study analyzed several functional indices, i.e., the increment in DBH and stand volume and biomass, in the damaged stands with various m...In order to investigate the effect of invastion by pine wood nematode(PWN), this study analyzed several functional indices, i.e., the increment in DBH and stand volume and biomass, in the damaged stands with various mixed percentages of Pinus massoniana and P. thunbergii and with different levels of damage. According to the results of rate of change in increment of DBH and stand volume, the forest ecosystem resistance against PWN increased with a reduction in the mixed ratio of pine. The resistance was highest with a mixed percentage of 50%. The invasion of PWN changed the corresponding relationship of increment between DBH and stand volume(pure stands > 7:3 conifer and broadleaf > 6:4 conifer and broadleaf > 5:5 conifer and broadleaf) among the P. thunbergii stands when there is no damage, but for P. massoniana stands this phenomenon did not occur. For the increment rate of DBH and stand volume, this significant change in P. thunbergii forest indicates that the resistance of pure P. thunbergii forest was higher than that of P. massoniana. The invasion of PWN accelerates the succession from pure stands to mixed stands and then to the broadleaf evergreen stands.展开更多
To investigate the dynamic changes in the artificial vegetation in an abandoned mining site,we analyzed the re lationships among community types,environmental variables and community structure in the process of vegeta...To investigate the dynamic changes in the artificial vegetation in an abandoned mining site,we analyzed the re lationships among community types,environmental variables and community structure in the process of vegetation restoration in the Antaibao mining site,China by survey of the communities and use of biological dating methods.By means of the quantitative classification method(two-way indicator-species analysis,TWINSPAN)and the ordination technique(de-trended correspondence analysis,DCA;and de-trended canonical correspondence analysis,DCCA),the plant communities were classified into seven groups:community I,Robinia pseudoacacia+Pimus tabulaeformis-Caragana kor-shinskii-Agropyron cristatum;community II,Robinia pseudoacacia-Hippophae rhamnoides-Artemisia capil-laries;community II,Ulmus pumila-Elaeagmus angu-stifolia-Artemisia capillaries;community IV,Caragana korshinskii-Agropyron cristatum+Artemisia capillaries;community V,Hippophae rhamnoides-Elymus dahur-icus;community VI,Elaeagnus angustifolia+Hippophae rhamnoides-Brassica jucea;community VII,Hippophae rhammoides+Elaeagnus angustifolia-Salsola collina.We conclude that the community types and diversity are mainly influenced by the succession time and the soil organic matter content.The forest community is more adaptable to the special inhabitation than the shrub community.展开更多
Kobresia meadows are the main pastures for animal husbandry on the Qinghai-Tibet Plateau,and may represent alternative steady states associated with different grazing intensities.The ability of other plant communities...Kobresia meadows are the main pastures for animal husbandry on the Qinghai-Tibet Plateau,and may represent alternative steady states associated with different grazing intensities.The ability of other plant communities to succeed these meadows remains unclear.In this study,the historical data of plant communities were analyzed in terms of the soil profile,and the present characteristics were identified by investigating their plant communities.Four types of steady states were identified,corresponding to grazing intensities of>11,8-11,5.5-8 and<5.5 sheep/ha.Drought alpine swamp meadows and shrub meadows could succeed to K.pygmaea meadows and K.humilis meadows under overgrazing,and their total biomass and edible biomass(estimated by Gramineae and Cyperaceae)decreased with increasing grazing intensity.The regime shift of the states occurred at a grazing intensity of 8-11 sheep/ha.This value thus represented the threshold of significant change in the production and ecological service function in the Kobresia meadow succession process.In general,increasing grazing intensities can adversely affect the service ability of meadows for livestock production and ecosystem stabilization.Our results revealed the potential degraded succession process of the alpine Kobresia meadow and the succession direction in the restoration process of degraded meadows.Additionally,this study provided a theoretical basis for evaluating the fitness between the livestock bearing capacity and carrying capacity in steady states and academic reference for policy setting pertaining to the utilization of Kobresia meadows in a sustainable development framework.展开更多
基金supported in part by the National Basic Research Program of China (2009CB421303)supported by National Natural Science Foundation of China (30970546)
文摘Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.
基金financially supported by the National Key Basic Research Development Program (No.2009CB119200)the Forestry Public Welfare Industry Scientific Research Project (No.200904029-3)
文摘In order to investigate the effect of invastion by pine wood nematode(PWN), this study analyzed several functional indices, i.e., the increment in DBH and stand volume and biomass, in the damaged stands with various mixed percentages of Pinus massoniana and P. thunbergii and with different levels of damage. According to the results of rate of change in increment of DBH and stand volume, the forest ecosystem resistance against PWN increased with a reduction in the mixed ratio of pine. The resistance was highest with a mixed percentage of 50%. The invasion of PWN changed the corresponding relationship of increment between DBH and stand volume(pure stands > 7:3 conifer and broadleaf > 6:4 conifer and broadleaf > 5:5 conifer and broadleaf) among the P. thunbergii stands when there is no damage, but for P. massoniana stands this phenomenon did not occur. For the increment rate of DBH and stand volume, this significant change in P. thunbergii forest indicates that the resistance of pure P. thunbergii forest was higher than that of P. massoniana. The invasion of PWN accelerates the succession from pure stands to mixed stands and then to the broadleaf evergreen stands.
基金This study was supported by the National Natural Science Foundation of China(Grant No.30870399)The Project of The Education Committee of Beijing(KE200410028014)China Postdoctoral Science Foundation(No.20060400636).
文摘To investigate the dynamic changes in the artificial vegetation in an abandoned mining site,we analyzed the re lationships among community types,environmental variables and community structure in the process of vegetation restoration in the Antaibao mining site,China by survey of the communities and use of biological dating methods.By means of the quantitative classification method(two-way indicator-species analysis,TWINSPAN)and the ordination technique(de-trended correspondence analysis,DCA;and de-trended canonical correspondence analysis,DCCA),the plant communities were classified into seven groups:community I,Robinia pseudoacacia+Pimus tabulaeformis-Caragana kor-shinskii-Agropyron cristatum;community II,Robinia pseudoacacia-Hippophae rhamnoides-Artemisia capil-laries;community II,Ulmus pumila-Elaeagmus angu-stifolia-Artemisia capillaries;community IV,Caragana korshinskii-Agropyron cristatum+Artemisia capillaries;community V,Hippophae rhamnoides-Elymus dahur-icus;community VI,Elaeagnus angustifolia+Hippophae rhamnoides-Brassica jucea;community VII,Hippophae rhammoides+Elaeagnus angustifolia-Salsola collina.We conclude that the community types and diversity are mainly influenced by the succession time and the soil organic matter content.The forest community is more adaptable to the special inhabitation than the shrub community.
基金the Natural Science Foundation of Qinghai Province(2020-ZJ-720)Joint research project of Three River Resource National Park funded by Chinese Academy of Sciences and Qinghai Provincial People's Government(LHZX-2020-08).
文摘Kobresia meadows are the main pastures for animal husbandry on the Qinghai-Tibet Plateau,and may represent alternative steady states associated with different grazing intensities.The ability of other plant communities to succeed these meadows remains unclear.In this study,the historical data of plant communities were analyzed in terms of the soil profile,and the present characteristics were identified by investigating their plant communities.Four types of steady states were identified,corresponding to grazing intensities of>11,8-11,5.5-8 and<5.5 sheep/ha.Drought alpine swamp meadows and shrub meadows could succeed to K.pygmaea meadows and K.humilis meadows under overgrazing,and their total biomass and edible biomass(estimated by Gramineae and Cyperaceae)decreased with increasing grazing intensity.The regime shift of the states occurred at a grazing intensity of 8-11 sheep/ha.This value thus represented the threshold of significant change in the production and ecological service function in the Kobresia meadow succession process.In general,increasing grazing intensities can adversely affect the service ability of meadows for livestock production and ecosystem stabilization.Our results revealed the potential degraded succession process of the alpine Kobresia meadow and the succession direction in the restoration process of degraded meadows.Additionally,this study provided a theoretical basis for evaluating the fitness between the livestock bearing capacity and carrying capacity in steady states and academic reference for policy setting pertaining to the utilization of Kobresia meadows in a sustainable development framework.
