降水量对宁强县飞播油松成苗的影响

为了研究降水量与飞播造林有苗样方频度和成苗量的关系，利用1997年汉中宁强县飞播油松成苗期有苗样方频度和成苗量调查数据，采用相关分析法和逐步回归模型分析法，分析了成苗效果与降水量的关系。结果表明，飞播油松成苗效果不仅取决于当地的年降水量，而且与当地降水量的分布密切相关。在不考虑飞播年限因素下，5月降水量是决定对照飞播油松成苗效果的关键因子，对有苗样方频度和成苗量模型值贡献率分别为96.9%和96.7%。而7月降水量对多效抗旱驱鼠剂（RPA）处理种子飞播油松有苗样方频度和成苗量作用最大，对模型值贡献率分别为71.6%和69.8%。在飞播年限协同作用下，5月降水量对对照和RPA油松成苗效果作用最强，贡献率均在95%以上。以飞播年限为权重，2月降水量与对照油松成苗效果相关性强，但5月降水量对模型值贡献率最大，分别为95.6%和96.2%。RPA成苗量与降水量关系与对照相同；而有苗样方频度与5月降水量关系紧密，其中7月降水量贡献率为63.9%，高于5月和2月的32.3%和3.8%。在当地降水量范围内，RPA模型值均大于对照，RPA拌种飞播后单位降水量的油松有苗样方频度和成苗量高，提高了土壤水分利用率。

Effects of Rainfall on Effective Adult Seedlings of Pinus tabulaeformis for Aerial Seeding in Ningqiang County

In order to study the relationship between the precipitation and the frequentness of the sampling plots with available seedlings (FOSPAS) and the quantity of available seedlings (QOAS),we used data of FOSPAS and QOAS of Pinus tabulaeformis during the seedling formation period in 1997 after aerial seeding in Hanzhong.Correlation analysis method and the stepwise regression model analysis method were adopted to analyze the relationship between seedling effect and precipitation.The results showed that the formation of adult seedlings not only depended on the local annual precipitation,but closely related to the local distribution of precipitation.Under the circumstances of without considering the factor of aerial seeding age,the precipitation in May was the key factor determining the effect of adult seedling in control area.Its contribution rates for model values of FOSPAS and QOAS were 96.9% and 96.7%,respectively.The July rainfall had the greatest effect FOSPAS and QOAS in RPA application area.The contributions of RPA to FOSPAS and QOAS were 71.6% and 69.8%,respectively.Under the consideration of the aerial seeding age,the precipitation in May had the strongest effect on seedling effect of P.tabulaeformis in control area and RPA area after aerial seeding,its contribution rates were more than 95%.Taking the age of aerial seeding age as the weight,there had strong correlation between the precipitation during the February and the seedling effect of P.tabulaeformis in the control area,but the precipitation in May on the contribution rate of model values was the most,95.6% and 96.2%,respectively.In RPA area,the relationship between QOAS and the precipitation was the same as control.However,relationship between FOSPAS and rainfall in May was close,with the contribution rate of 63.9%,higher than those in May (32.3%) and February (3.8%).Under the range of local rainfall,the RPA model values were larger than the control,the seed dressing used RPA after afforestation by aerial seeding,FOSPAS and QOAS increased in the unit precipitation,and the utilization rate of soil moisture was improved.