摘 要

本文以位于南京市浦口区的12年生杨树（Populus deltoides Bartr. cv. “Lux”）人工林为研究对象，调查了林分生态系统的养分分布特征以及不同季节杨树各器官主要养分浓度的动态变化。主要的结果如下：（1）杨树各器官的Ca浓度最大，K、N、Mg次之，P最小；杨树不同器官的生物量呈树干gt;树根gt;树枝gt;树皮gt;树叶，其中树干占林木地上部分生物量的66%左右，但树干所含养分含量占林木地上部分养分总量的36.2%；树枝和树叶生物量分别占林木生物量总量的17.6%和3.6%，但其养分含量分别占养分总量29.2%和14.7%；（2）杨树叶片中的N、P、K浓度在4～8月较大，之后逐渐下降； 在生长初期（4～5月）和生长旺盛期（8月左右）叶片中的Ca和Mg浓度较低；在生长旺盛期（6～8月）杨树枝条和根系中的N和P浓度较低，而Ca和Mg浓度在杨树年生长过程中基本上呈增加的趋势；与其他器官相比，杨树树干和树皮中的养分浓度较低，尤其是树干；当杨树开始落叶时，树干和树皮中的养分浓度有所增加。

关键词：杨树；人工林；养分分布；养分动态

Study on nutrient distribution and biochemical cycling of a poplar plantation

ABSTRACT

In this paper, we mainly investigated nutrient distribution characteristics of a poplar plantation, and the dynamic changes of main nutrient concentrations of different poplar organs during different poplar growth stages, in Pukou, Jiangsu, China. The main results are as follows: (1) the concentrations of Ca were the highest among different organs of poplar, followed by K, N, Mg and P were the smallest. The order of biomass of different poplar organs was stemwood gt; root gt; branch gt; stembark gt; foliage; stemwood accounted for about 66% of aboveground part biomass of poplar trees, while nutrients accumulated in the stemwood accounted for only 36.2% of nutrients accumulated in aboveground parts of poplar trees; moreover, the branch and foliage accounted for 17.6% and 3.6% of total tree biomass, respectively, but their nutrient contents accounted for 29.2% and 14.7% of nutrients accumulated in the entire tree, respectively; (2) the concentrations of N, P, K in poplar foliage were higher during April to August, then gradually decreased; in the early growth stage (form April to May) and August, the concentrations of Ca and Mg in poplar foliage were lower; the lower N and P concentrations showed in poplar branches and roots during June to August, and the concentrations of Ca and Mg in different poplar organs showed an increasing trend during poplar growth stages; nutrient concentrations in stemwood and stembark were lower than the other organs, especially for stemwood; however, nutrient concentrations in these two organs also showed increased when poplar trees were during defoliation period.

Key words：Poplar; Plantation; Nutrient distribution; Nutrient dynamic

目 录

1综述 1

1.1杨树人工林的基本概况 1

1.1.1杨树人工林的发展 1

1.1.2杨树的形态特征 1

1.1.3杨树的用途 1

1.2人工林生态系统的养分分布状况 2

1.3人工林的生物循环 3

2实验材料和方法 5

2.1试验地概况 5

2.2实验样品采集 5

2.3测定方法 5

2.4计算方法 6

3结果与分析 7

3.1杨树人工林生态系统中林木、林下植被和土壤的养分分布状况 7

3.2杨树各器官养分浓度的时间动态特征 8

3.2.1杨树各器官氮浓度的动态变化 8

3.2.2杨树各器官磷浓度的动态变化 9

3.2.3杨树各器官钾浓度的动态变化 11

3.2.4杨树各器官钙浓度的动态变化 12

3.2.5杨树各器官镁浓度的动态变化 13

4讨论与结论 15

4.1讨论 15

4.1.1杨树人工林各组分养分分布分析 15

4.1.2杨树不同器官养分浓度的动态变化特征 15

4.2结论 16

致 谢 18

参考文献 19

1综述

1.1杨树人工林的基本概况

1.1.1杨树人工林的发展

人工林是按一定的目的和人们需要，集中营造在交通较为方便的地方，并普遍采取良种、集约经营方式进行营造和培育。杨树人工林具有生长快、产量高、加工利用方便和获得效益早、木材规格、质量较稳定等特点。据1995年统计，世界其他国家杨树人工林面积140万公顷，我国杨树人工林面积约700万公顷，占全国人工林总面积的19%。人工林一般采取短轮伐期连栽经营和全树利用的方式，林地土壤退化现象日趋严重，这些问题越来越受到研究人员的关注。本文调查了杨树人工林的林木生长和养分分布特征，以了解杨树的生物量和养分分布特征以及养分利用特征；并研究了不同季节杨树各器官主要养分浓度的动态变化，探讨了杨树不同器官养分动态变化规律，为进一步了解杨树养分生物和化学循环特征，制定杨树人工林可持续经营措施提供理论依据。

1.1.2杨树的形态特征