汉中RPA拌种飞播油松高生长与降水关系分析

降水是主要的生态因子，对林木的生长起着至关重要的作用。为此利用汉中1997年飞播油松14 a调查资料，结合当地1997-2011年降水情况，采用聚类分析法、相关分析法和逐步回归模型法研究树高、树高年生长量和树高生长年增量与降水量的关系，探讨RPA拌种飞播对油松利用林地水分的影响。结果表明，树高与年、3月和8月降水量呈极显著正相关，与1月降水量负相关极显著，与12月降水量呈显著负相关。对照油松高年生长量与8月和11月降水量正相关显著；RPA树高年生长量与3月降水量呈极显著正相关，与年、8月和7月降水量呈显著正相关，而与1月降水量负相关显著。4月降水量与对照油松高生长年增量呈显著负相关，与RPA负相关极显著。剔除树龄因子，树高对3月、2月和11月降水反应敏感；3月、7月和9月降水量对RPA和对照树高模型贡献分别为54.2%和52.5%。RPA树高年生长量优化模型中，排除了年降水量的作用，3月、4月、8月、7月、12月、11月和1月降水量作用依次降低，贡献介于2.7%～27.2%；对照模型中，年降水量贡献47.1%，8月、3月和12月降水分别贡献29.8%、10.7%和9.7%。4月降水量对树高生长年增量作用较大，1月和12月降水也与RPA年增量相关。引入时间因子，3月降水对树高作用较大。树龄权重下，3月降水量对树高作用最大，而年降水量是影响树高年生长量的关键因子。

Relationship between Precipitation and Height Growth of Pinus tabulaeformis by Using RPA Dressing Seeds after Aerial Seeding in Hanzhong

Precipitation is a key climate factor that plays a vitally important role on forest tree growth.Afforestation by aerial seeding was conducted in 1997 by using Pinus tabulaeformis seeds dressed with RPA in Hanzhong of Shaanxi Province.Related data were collected during 1997 to 2011.The relationship between tree height,annual increment of tree height and annual height growth acceleration and precipitations were analyzed by using cluster analysis,correlation analysis and stepwise regression model.The effect of seed dressing with RPA on water use efficiency of the trees was explored.The results showed that,tree height was very significantly and positively correlated to annual precipitation,and precipitations in March and August,but it was very significantly and negatively correlated to the precipitation in January and significantly and negatively correlated to the precipitation in December.Annual height increment of Pinus tabulaeformis in control area had a significantly positive correlation with rainfall in August and November.And in RPA area,tree height had a very significantly positive correlation with precipitation in March,and had significantly positive correlation with annual rainfall,and rainfalls in August and July,but had a significantly negative correlation with precipitation in January.April precipitation was significantly and negatively correlated to annual increment of tree height in control area,and was very significantly and negatively correlated to annual increment of tree height in RPA area.Ignoring tree age factor,tree height was sensitive to the precipitation in March,February and November.Contributions of the precipitations in March,July and September to tree height in control area and RPA area were 54.2% and 52.5%,respectively.In the optimization model of annual increment of tree height in RPA area,excluding the role of annual precipitation,and effects of precipitations in March,April,June,August,December,November and January reduced successively,and their contributions decreased from 2.7 % to 2.72%.In control model,the annual precipitation contributed 47.1% to the tree height,precipitations in August March and December contributed 29.8%,10.7% and 9.7%,respectively.April precipitation largely effected the annual height growth,precipitation in January and December was also associated with annual height growth in RPA area.After introducing time factor in the model ,the role of precipitation in March on tree height was large.Under tree ages as weight,the role of precipitation in March was the largest in the tree height model,and the annual precipitation was the key factor to influence annual increment of tree height.