[Objective] The aim of this study was to evaluate the effect of livestock exclusion on the health of grassland ecosystem accurately and quantitatively. [Method] One open grazing site and five seasonal exclusion sites,...[Objective] The aim of this study was to evaluate the effect of livestock exclusion on the health of grassland ecosystem accurately and quantitatively. [Method] One open grazing site and five seasonal exclusion sites, which had the same vegetation composition （taking Leymus chinensis and Stipa krylovii as main species） and soil type, were chosen as research objects for the VOR and CVOR evaluation of the effect of open grazing and livestock exclusion on the health of typical steppes, and for building the calculation model for VOR and CVOR indices to evaluate the health of typical steppes with different exclusion periods. [ Result] The VOR and CVOR composite indices both could accurately evaluate the health of typical steppes, and the evaluation results from the both indices were quite consistent. Although the condition （C）, vigor（V）, organization （O） and resilience（ R ） indices changed differently in different exclusion periods, the VOR and CVOR composite indices increased gradually with the peri- od of exclusion prolonged, and the health condition of typical steppe changed from ＂alert＂ level （in the open grazing and earlier exclusion period） to ＂healthy＂ level （after 13 to 20 years＇exclusion）. [ Conclusion] The application of exclusion was beneficial to the recovery of degraded grassland ecosystem.展开更多
Three complexes [AMP][Ni（mnt）2]·CH3CN （1, AMP = 1-（9-anthrylmethyl）pyri- dinium）, [DPI]2[Ni（nmt）2]I （2, DPI = diphenyliodonium） and [DD][Ni（mnt）2]2·2H2O （3, DD = dimethylenediamine） have been p...Three complexes [AMP][Ni（mnt）2]·CH3CN （1, AMP = 1-（9-anthrylmethyl）pyri- dinium）, [DPI]2[Ni（nmt）2]I （2, DPI = diphenyliodonium） and [DD][Ni（mnt）2]2·2H2O （3, DD = dimethylenediamine） have been prepared and characterized by elemental analyses and IR spectroscopy. X-ray diffraction studies show that three complexes crystallize in the same triclinic space group Pi, and anionic accumulations are formed in a column shape. The results show that different counter-cations could induce versatile anionic stacks. The structures of three complexes exhibit rich hydrogen bonding interactions. In addition, UV-VIS properties of them are also investigated.展开更多
基金supported by National Key Fundamental Research and Development Fund of China (No.2007CB106800)
文摘[Objective] The aim of this study was to evaluate the effect of livestock exclusion on the health of grassland ecosystem accurately and quantitatively. [Method] One open grazing site and five seasonal exclusion sites, which had the same vegetation composition （taking Leymus chinensis and Stipa krylovii as main species） and soil type, were chosen as research objects for the VOR and CVOR evaluation of the effect of open grazing and livestock exclusion on the health of typical steppes, and for building the calculation model for VOR and CVOR indices to evaluate the health of typical steppes with different exclusion periods. [ Result] The VOR and CVOR composite indices both could accurately evaluate the health of typical steppes, and the evaluation results from the both indices were quite consistent. Although the condition （C）, vigor（V）, organization （O） and resilience（ R ） indices changed differently in different exclusion periods, the VOR and CVOR composite indices increased gradually with the peri- od of exclusion prolonged, and the health condition of typical steppe changed from ＂alert＂ level （in the open grazing and earlier exclusion period） to ＂healthy＂ level （after 13 to 20 years＇exclusion）. [ Conclusion] The application of exclusion was beneficial to the recovery of degraded grassland ecosystem.
基金Supported by Basic&Advanced Technology Research Projects of Henan Science and Technology Department
文摘Three complexes [AMP][Ni（mnt）2]·CH3CN （1, AMP = 1-（9-anthrylmethyl）pyri- dinium）, [DPI]2[Ni（nmt）2]I （2, DPI = diphenyliodonium） and [DD][Ni（mnt）2]2·2H2O （3, DD = dimethylenediamine） have been prepared and characterized by elemental analyses and IR spectroscopy. X-ray diffraction studies show that three complexes crystallize in the same triclinic space group Pi, and anionic accumulations are formed in a column shape. The results show that different counter-cations could induce versatile anionic stacks. The structures of three complexes exhibit rich hydrogen bonding interactions. In addition, UV-VIS properties of them are also investigated.
