多年生黑麦草刈后2 d 内,其再生草各器官中的碳水化合物主要来源于残茬,刈后3 d内,再生器官中的氮素也是主要来源于残茬。刈前根部贮藏的碳水化合物和氮素对再生的贡献小于残茬。刈割3 d 后,根中新吸收的氮素和残茬内新同化的碳水化合...多年生黑麦草刈后2 d 内,其再生草各器官中的碳水化合物主要来源于残茬,刈后3 d内,再生器官中的氮素也是主要来源于残茬。刈前根部贮藏的碳水化合物和氮素对再生的贡献小于残茬。刈割3 d 后,根中新吸收的氮素和残茬内新同化的碳水化合物迅速增加,再生器官中,以新同化的碳水化合物和新吸收的氮素占绝对优势。在植株再生中,叶片生长区内刈前贮藏的碳水化合物和氮素下降的程度大于残茬和根部,其中,贮藏的氮素下降持续的时间长于贮藏的碳水化合物。高频率的刈割强烈地干扰了多年生黑麦草的能量贮藏和氮素平衡。展开更多
Aims Grasslands are widely used for production of livestock,which depend on the nutritive value of herbage species.However,there are still large uncertainties as to how grazing,precipitation and growing season interac...Aims Grasslands are widely used for production of livestock,which depend on the nutritive value of herbage species.However,there are still large uncertainties as to how grazing,precipitation and growing season interactively affect herbage nutritive value.Methods Here,based on a grazing experiment with seven grazing intensities in an Inner Mongolian grassland since the year 2005,we analysed nutritive value of four dominant grass species from June to September in both a relatively wetter year(2008)and a drier year(2010).Herbage with high nutritive value is characterized by high concentration of crude protein,high concentration of cellulase digestible organic matter and low concentration of neutral detergent fibre.Important Findings We found that(i)grazing significantly increased the nutritive value of Leymus chinensis,Agropyron michnoi and Cleistogenes squarrosa but had minor effects on the nutritive value of Stipa grandis.(ii)For all species,nutritive values were greater in the wetter year than in the drier year and were greatest in the early growing season(June)and lowest at the end of the growing season(September).Inter-annual and inter-seasonal variations in nutritive value were much greater for L.chinensis and A.michnoi than for C.squarrosa and S.grandis,suggesting higher water use efficiency for the latter two species.(iii)Grazing significantly decreased the drought resistance of three species,but not of S.grandis.(iv)Grazing significantly increased inter-month variation in nutritive value for L.chinensis and A.michnoi but had relatively minor or no effects on that of C.squarrosa and S.grandis.Therefore,grazing effects on species nutritive values showed strong inter-annual and seasonal patterns,and species-specific responses might be related to species traits(i.e.water use efficiency,digestibility).Our results have important implications for ecosystem management of arid and semiarid grasslands under intense grazing and global climatic change.展开更多
文摘多年生黑麦草刈后2 d 内,其再生草各器官中的碳水化合物主要来源于残茬,刈后3 d内,再生器官中的氮素也是主要来源于残茬。刈前根部贮藏的碳水化合物和氮素对再生的贡献小于残茬。刈割3 d 后,根中新吸收的氮素和残茬内新同化的碳水化合物迅速增加,再生器官中,以新同化的碳水化合物和新吸收的氮素占绝对优势。在植株再生中,叶片生长区内刈前贮藏的碳水化合物和氮素下降的程度大于残茬和根部,其中,贮藏的氮素下降持续的时间长于贮藏的碳水化合物。高频率的刈割强烈地干扰了多年生黑麦草的能量贮藏和氮素平衡。
基金Deutsche Forschungsgemeinschaft(DFG)for funding the research group 536 MAGIM(Matter fluxes of grasslands in Inner Mongolia as influenced by stocking rate)and the subsequent Lot-Grass projectthe Ministry of Education of China(IRT1259).
文摘Aims Grasslands are widely used for production of livestock,which depend on the nutritive value of herbage species.However,there are still large uncertainties as to how grazing,precipitation and growing season interactively affect herbage nutritive value.Methods Here,based on a grazing experiment with seven grazing intensities in an Inner Mongolian grassland since the year 2005,we analysed nutritive value of four dominant grass species from June to September in both a relatively wetter year(2008)and a drier year(2010).Herbage with high nutritive value is characterized by high concentration of crude protein,high concentration of cellulase digestible organic matter and low concentration of neutral detergent fibre.Important Findings We found that(i)grazing significantly increased the nutritive value of Leymus chinensis,Agropyron michnoi and Cleistogenes squarrosa but had minor effects on the nutritive value of Stipa grandis.(ii)For all species,nutritive values were greater in the wetter year than in the drier year and were greatest in the early growing season(June)and lowest at the end of the growing season(September).Inter-annual and inter-seasonal variations in nutritive value were much greater for L.chinensis and A.michnoi than for C.squarrosa and S.grandis,suggesting higher water use efficiency for the latter two species.(iii)Grazing significantly decreased the drought resistance of three species,but not of S.grandis.(iv)Grazing significantly increased inter-month variation in nutritive value for L.chinensis and A.michnoi but had relatively minor or no effects on that of C.squarrosa and S.grandis.Therefore,grazing effects on species nutritive values showed strong inter-annual and seasonal patterns,and species-specific responses might be related to species traits(i.e.water use efficiency,digestibility).Our results have important implications for ecosystem management of arid and semiarid grasslands under intense grazing and global climatic change.
