准噶尔盆地农田防护林树种青杨的生长规律研究

揭示杨树人工林在生长特性方面的变化规律对进一步挖掘杨树人工林的生产潜力和保证林木速生丰产具有十分重要的意义。以新疆准噶尔盆地农田防护林21a生青杨为研究对象,运用树干解析法对其树高、胸径、材积的生长规律进行调查研究。结果表明:青杨生长过程可以分为三个时期,第0～6a为幼树期,第7～15a为速生期,第16～21a为成熟期。树高速生阶段集中在第3～14a,胸径速生期为第6～16a,材积速生期为第7～15a。在胸径快速增长期间适当进行施肥管理,有利于培育优质大径材。青杨数量成熟年龄约为18a,初始防护成熟龄在第8a。建立的青杨树高、胸径和材积生长的六种模型:幂函数型、对数型、指数型、二/三次多项式回归型以及Logistic生长方程均取得较好的模拟效果(R2>0.809),三次多项式方程是模拟青杨树高和胸径生长进程的最佳模型,Logistic模型是模拟青杨材积生长进程的最佳模型。

The growth law of farmland protective forest species Populus cathayana Rehd. in Junggar Basin

Research on the growth characteristics of poplar plantation is of great significance in the further excavation of poplar plantation potential production and in the guarantee of its fast-growing.The 21 years old Populus cathayana Rehd.plantation was chosen to study its whole process of growth,which were planted in the Junggar Basin in Xinjiang as the farmland protective forest.The tree height,diameter at breast height(DBH) and volume growth characteristics of the tree were studied through trunk analysis method.The results showed that the growth process of P.cathayana was divided into three periods: 0-6a was the young stand period,7-15a was the fast-growing period,16-21a was the mature period.In the fasting-growing stage of DBH,if the suitable fertilizer management was carried on,it would be good to the cultivation of large and medium-sized diameter timber.The maturity age for largest volume and initial protective maturity period of P.cathayana was the 18a and 8a,respectively.The correlation coefficients of six kinds of models describing the tree height,DBH and volume growth process are all higher than 0.809,which means that all the six growth models are fitting excellent.Compared with the other five models,cubic polynomial regression model is the optimal one to describe the growth process of P.cathayana tree height and DBH with high coefficient of correlation(0.997 and 0.998).While,the Logistic model may accurately describe the growth process of P.cathayana volume with high coefficient of correlation(0.994).