|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | The effects of simulated nitrogen deposition on extracellular enzyme activities of litter and soil among different-aged stands of larch显示文摘Aims Nitrogen(N)addition could affect the rate of forest litter and soil organic matter decomposition by regulating extracellular enzyme activity(EEa).The impact of N addition on EEa may differ across different age stands with different organic matter quality.We were interested in whether the impact of N addition on EEa in litter and mineral soil during the growing season was dependent on stand age of a larch plantation in North China.Methods We added three levels of N(0,20 and 50 kg N ha^(−1) year^(−1))in three age stands(11,20 and 45 years old)of Larix principis-rupprech-tii plantation in North China.We measured potential activities of β-1,4-glucosidase(b),cellobiohydrolase(Cb),β-1,4-N-acetyl-glucosaminidase(Nag)and phenol oxidase(Po)in litter(organic horizon)and mineral soil(0-10 cm)during the second growing sea-son after N amendment.We also measured C and N concentrations,microbial biomass C and N,and KCl-extractable ammonium and nitrate in both litter and mineral soil.Important Findings We observed unimodal patterns of EEa during the growing season in all three stands,consistent with the seasonal variations of soil temperature.stand age had a strong effect on EEa in both litter and mineral soil,and this effect differed between litter and mineral soil as well as between different enzymes.N addition did not significantly affect the activities of b or Cb but significantly suppressed the activity of Nag in litter.We also found stand age-specific responses of Po activity to N addition in both litter and mineral soil.N addition suppressed Po activity of the high C:N ratio litters in 20-and 45-year-old stands but had no significant effect on Po activity of the low C:N ratio litter in 11-year-old stand.moreover,N addition inhibited Po activity of the high C:N ratio soil in 20-year-old stand but had no significant impact on Po activity of the low C:N ratio soils in 11-and 45-year-old stands.overall,stand age had a greater effect on EEa in litter and mineral soil compared to 2 years of N addition.moreover,the effect of N addition on Po activity is stand age dependent,which may affect the long-term soil carbon storage in this forest. | Yuecun Ma Biao Zhu Zhenzhong Sun Chuang Zhao Yan Yang Shilong Piao | 2014 | Journal of Plant Ecology2014，7，3： | 14 |
| 2 | NEECF: a project of nutrient enrichment experiments in China’s forests显示文摘Anthropogenic nitrogen(N)emissions to atmosphere have increased dramatically in China since 1980s,and this increase has aroused great concerns on its ecological impacts on terrestrial ecosystems.Previous studies have showed that terrestrial ecosystems in China are acting as a large carbon(C)sink,but its potential in the future remains largely uncertain.So far little work on the impacts of the N deposition on C sequestration in China’s terrestrial ecosystems has been assessed at a national scale.Aiming to assess and predict how ecological processes especially the C cycling respond to the increasing N deposition in China’s forests,recently researchers from Peking University and their partners have established a manipulation experimental network on the ecological effects of the N deposition:Nutrient Enrichment Experiments in China’s Forests Project(NEECF).The NEECF comprises 10 experiments at 7 sites located from north to south China,covering major zonal forest vegetation in eastern China from boreal forest in Greater Khingan Mountains to tropical forests in Hainan Island.This paper introduces the framework of the NEECF project and its potential policy implications. | Enzai Du Zhang Zhou Peng Li Xueyang Hu Yuecun Ma Wei Wang Chengyang Zheng Jianxiao Zhu Jin-Sheng He Jingyun Fang | 2013 | Journal of Plant Ecology2013，6，5： | 13 |
| 3 | In-situ surface transformation of magnesium to protect against oxidation at elevated temperatures显示文摘The native oxide thin scale on magnesium(Mg)surface appears continuous and crack-free,but cannot protect the Mg matrix from further oxidation,especially at elevated temperatures.This thermal oxidation process is witnessed in its entirety using a home-made in-situ heating device inside an environmental electron transmission microscope.We proposed,and verified with real-time experimental evidence,that transforming the native oxide scale into a thin continuous surface layer with high vacancy formation energy(low vacancy concentration),for example MgCO3,can effectively protect Mg from high-temperature oxidation and raise the threshold oxidation temperature by at least two hundred degrees. | Yuecun Wang Meng Li Yueqing Yang Xin’ai Zhao Evan Ma Zhiwei Shan | 2020 | Journal of Materials Science & Technology2020，44，9： | 1 |
| 4 | Changes in satellite‐derived spring vegetation green‐up date and its linkage to climate in China from 1982 to 2010: a multimethod analysis显示文摘 | Nan Cong Tao Wang Huijuan Nan Yuecun Ma Xuhui Wang Ranga B. Myneni Shilong Piao | 2012 | Glob Change Biol2012，，： | 1 |
| 5 | Estimation of mountainous farmland area in China based on GIS and RS: A case study of Lincheng County显示文摘 | Limei Tan Liu J T Ma Yuecun | 2009 | Journal of Food Agriculture & Environment2009，7，2： | 1 |
您所在的机构暂未开通此部分的功能，请联系管理员