修枝对滩地杨树生长和养分的短期影响

以怀宁县皖河滩地杨树林为研究对象,对修枝前后林木与土壤中的养分含量进行了研究.结果表明:(1)一定修枝强度下,修枝对杨树的树高和胸径生长影响显著(P<0.05),但随着修枝强度增大对树高生长的影响是先增大后减小,而对胸径的影响是一直增大;(2)修枝会降低林地土壤全氮含量,但对土壤全氮、全磷、速效磷和钾含量影响不显著(P>0.05);(3)修枝对不同土层深度土壤养分影响不显著(P>0.05),但全氮、全磷、速效磷含量均随着土层深度的加深而逐渐减少,钾、钙、镁含量基本相同;同一修枝强度下,各种养分含量在不同方向基本持平,只有钙的含量在每个方向都是以轻度修枝最大;(4)植物各器官中,全氮含量以根最高,3种修枝强度下,随着年龄增大枝的全氮含量降低,根的全氮含量增加.同时,修枝对上部枝的全氮含量影响显著(P<0.05);修枝强度对中部枝和大于5 mm根的全氮含量影响显著(P<0.05);修枝对植物各组分全磷含量影响不显著(P>0.05);除中部枝的钙含量在轻度修剪与强度修剪有显著差异外(P<0.05),修枝对植物钾、钙、镁的影响不显著(P>0.05),但随着枝的生长钾、钙、镁的含量有降低的趋势;随着根的生长.钾、钙、镁的含量变化规律不明显.

Short Effects of Pruning on Growth and Nutrient of Poplar in Beach Land

The paper studied the short effects of pruning on growth and nutrient of Poplar in Beach Land. The pruning levels were respectively light(25% crown was pruned) , strong(40% crown was pruned) and the control (unpruned). Heights and diameters at breast height (DBH), nutrient of tree organ and soil were measured. The results were; (1) In a certain pruning intensities, the difference of height growth and diameters at breast height (DBH) for different pruning treatment was significant (P<0. 05). With the pruning intensity enhancing, height growth rate increased firstly and then diminished, but the DBH always increasing; (2) Pruning would reduce total nitrogen contents in the soil, but the difference total nitrogen, total phosphorus, available phosphorus, potassium, calcium, magnesium contents was not significant (P>0. 05) ; (3) The difference of soil nutrient in different soil depth was not significant (P>0. 05), and the content of potassium, calcium and magnesium was basically identical, but the deeper of soil depth, the smaller the content of total nitrogen, total phosphorus, available phosphorus. In the same pruning intensities, the nutrient content in the difference direction was basically identical, except the calcium content in the unpruned stand soil was bigger than pruned; (4) In all organs, the nutrient content of root was highest. In three pruning intensity, the content of total nutrient in the branches reduced along with the tree grew, and the content of total nutrient in the roots increased, at the same time, the difference of total nutrient in upper branch was significant (P<0. 05); the difference of total nutrient of the medium branch and exceed 5 mm root in different pruning intensity was significant (P<0. 05); the difference of total phosphorus was not significant (P>0. 05);except that the difference of calcium in medium branch in pruned stand was significant(P<0. 05), the difference of potassium, calcium, magnesium content was not significant (P>0. 05), but they reduced with branch growing and keep invariable with root growing.