The Effect of Different Mixture Model of Populus alba var.pyramidalis on the Damaged Status by Anoplophora glabripennis and Tree Growth

In order to confirm the effect that reasonable disposition of multi-tree species has the potential to increase resistance of trees to Anoplophora glabripennis,three different disposition model forests were sampled in experimental forest belonging to Xinhuaqiao Farm of Tree Seed and Seeding in Ningxia.By conducting stem analysis for standard tree of P.alba var.pyramidalis,the increments of P.alba var.pyramidalis within three disposition models were cpmpared.The results are described as follows,there were significant differences in the height and timber volume within three different disposition model forest(difference level 99%),but no significant difference in dbh of P.alba var.pyramidalis was observed.(Among) them,the individual P.alba var.pyramidalis with the greatest increment of total timber volume was that in mixed forest of P.alba var.pyramidalis and Acer negundo,followed by that in mixded forest of P.alba var.pyramidalis and Populus×xiaozhuanica cv.'Opera'and that in the pure forest of P. alba var.pyramidalis.More or less,the growth status of P.alba var.pyramidalis in the mixed forest with multi-tree species disposition was better than that in pure forest.While,the comparison of the increments of total timber volume per ha of three different disposition model forests showed that the largest one was that in the mixed forest of P.alba var.pyramidalis and Acer negundo,followed by that in the pure forest of P.alba var.pyramidalis and that in mixded forest of P.alba var.pyramidalis and Populus×xiaozhuanica cv.'Opera'.Taking into account the individual timber volume increments and the total increments of forest tree timber volume per ha,was showed that the mixed forest of P.alba var.pyramidalis and Acer negundo was the best among the 3 models.