【摘要】 为了解水曲柳林分化学计量特征和养分再吸收率与N、P元素供应的关系,以15年生水曲柳(Fraxinus mandshurica)人工林为研究对象,测定氮(N)、磷(P)添加后水曲柳林分土壤、成熟叶片和衰老叶片养分浓度的变化。结果表明:N、P添加后水曲柳成熟叶N、P浓度和土壤C、N浓度均逐渐增加,而衰老叶P浓度逐渐降低;水曲柳成熟叶C∶N、C∶P和土壤C∶P均随N、P添加而降低,而成熟叶和土壤N∶P仅随P添加而降低,但是衰老叶C∶P、N∶P均随P添加量增加而显著提高; N、P添加后水曲柳叶片N、P再吸收率均提高,其中P再吸收率变化最大,高氮和高磷处理下P再吸收率分别比CK提高2. 3倍和2. 7倍,且叶片P再吸收率与成熟叶C∶P呈显著负相关,但是与衰老叶C∶P、N∶P呈极显著正相关。N、P添加后水曲柳成熟叶N∶P的变化和N、P再吸收率的提高表明:P是限制本研究中水曲柳林木生长的重要因素,N、P添加可以提高水曲柳N、P的利用效率,并改善水曲柳林分的养分状况。更多还原

【Abstract】 In order to understand the relation between nutrient stoichiometric characteristics and resorption efficiency of Fraxinus mandshurica stand and the N and P supply,N and P concentrations of soils and leaves were determined in the 15-year-old Fraxinus mandshurica plantations after N and P addition. The results showed that: with the increasing of N and P supply,the N and P concentrations of mature leaves and the C and N concentrations of soil increased,while the P concentration of senescent leaves gradually decreased. The C∶ N and C∶ P ratios of mature leaves and C∶ P ratio of soils decreased under N and P addition,and N∶ P ratio of mature leaves and soils decreased under P addition,but C∶ P and N∶ P ratios of senescent leaves increased significantly with the increasing P supply. It showed high resorption efficiency of N and P in leaves under N and P addition,and among them P resorption efficiency were higher. The P resorption efficiency under high nitrogen and high phosphorus treatment increased by 2. 3 times and 2. 7 times of CK,respectively,and the leaf P resorption efficiency and mature leaf C∶ P showed a significantly negative correlation,but it was significantly positively correlated with senescent leaves C∶ P,N∶ P. Our study indicates that N and P addition can adjust N∶ P ratios of mature leaves and increase N and P resorption of Fraxinus mandshurica stand,which suggests that P is an important limiting element of Fraxinus mandshurica during growth,moreover,N and P addition can increase nutrient utilization efficiency and improve nutrient status in the plantation of Fraxinus mandshurica.更多还原