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以亚热带不同林龄(3、8、14、21、46年生)杉木人工林为研究对象,探索不同叶龄(当年生、1年生、2年生和3年生)叶片氮、磷养分状况和水分利用效率的差异及其相互关系.结果表明:不同叶龄水分利用效率差异显著,总体趋势为当年生>1年生>2年生>3年生,而林龄对水分利用效率影响不显著.叶片N/P为11.4~19.6,其中,幼龄林和老龄林叶片N/P高于速生期林分叶片N/P,氮、磷浓度随叶龄的变化趋势一致,为当年生>1年生>2年生>3年生.水分利用效率随林龄变化不显著,可能是因为叶片光合速率和气孔导度同时随林龄下降.水分利用效率与叶片氮浓度相关不显著,而与叶片磷浓度呈显著正相关,与N/P呈显著负相关,表明在氮沉降增加的背景下,亚热带森林中植物磷含量逐渐成为影响水分利用效率的重要因子.
The objective of this study was to investigate the nutrient status and water use efficiency of nitrogen and phosphorus in leaves of different leaf age (annual, 1 year, 2 years and 3 years) in subtropical China fir plantation (3, 8, 14, 21, 46 years) The results showed that there was significant difference in water use efficiency of different leaf ages, and the overall trend was annual> 1 year> 2 years> 3 years old, while the stand age had no significant effect on water use efficiency. The results showed that N / P in young and aged stands was higher than that in fast growing stands, and the change trend of N and P was the same with leaf age. The annual N rates> 1 year> 2 years> 3 years.Water use efficiency with age did not change significantly, probably because the leaf photosynthetic rate and stomatal conductance at the same time with the decline of stand age.Water use efficiency and leaf nitrogen concentration was not significant, but with leaf phosphorus concentration was positively correlated, And negatively correlated with N / P, indicating that plant phosphorus content in subtropical forests has gradually become an important factor affecting water use efficiency in the context of increased nitrogen deposition.