连续年龄序列桉树人工林凋落物量及养分通量

Litter production and its nutrient fluxes in an age sequence of Eucalyptus plantations.

在福建漳州地区,对连续年龄序列(2、3、4、5、6年生)的尾巨桉(Eucalyptus grandis×E.urophylla)人工林凋落物量及其养分通量进行了研究。结果表明:不同林龄(2、3、4、5和6年生)的年凋落物总量分别为2796.65、3098.10、4489.13、4200.72和3692.40kg.hm-2,呈现先期增加,4年生后出现缓慢下降的趋势。各年龄段林分凋落物量均显示出明显的季节动态,其中3、4和6年生林分呈单峰型,前二者出现在6月,后者出现在4月;而2和5年生林分则出现2个峰值,前一个峰值出现在4月,后一峰值出现在6月。在凋落物的组成中,落叶占总凋落物量的84.86%～90.04%,其次分别为碎屑物(5.01%～6.70%)、落枝(2.95%～4.52%)、树皮(2.64%～3.62%)和落果(0.30%～0.55%)。凋落物各组分中,主要养分元素含量大小顺序为N>Ca>K>Mg>P。各龄级桉树人工林凋落物中5种元素的年通量的大小顺序表现为:4年生(133.20kg.hm-2)>5年生(124.98kg.hm-2)>6年生(97.56kg.hm-2)>3年生(90.51kg.hm-2)>2年生(86.01kg.hm-2)。

The measurements on the litter production and its nutrient fluxes in an age sequence of Eucalyptus grandis × E. urophyUas plantations were studied in Zhangzhou, Fujian Province. The results showed that the annual litter production of 2-, 3-, 4-, 5-, and 6-year old E. grand/s × E. urophyllas plantations was 2796. 65, 3098. 10, 4489. 13, 4200. 72, and 3692. 40 kg·hm^-2, respectively, showing an increase with stand age at early stage, but slightly decline after 4-year- old. The litter production of 3- and 4-year-old stands and that of 6-year-old stand showed a single peak in early summer （June） and in mid-spring （April）, respectively, while that of 2- and 5- year-old stands exhibited one peak in mid-spring （April） and another peak in summer （June）. In the litters, fallen leaves occupied the greatest proportion （84. 86%-90. 04% ）, followed by miscellaneous materials （ 5.01%- 6.70% ）, branches （ 2. 95%- 4. 52% ） , barks （ 2.64%- 3.62% ）, and fruits （0. 30%-0. 55% ）. The nutrient contents in the litters were N 〉 Ca 〉 K 〉 Mg 〉 P, and their annual fluxes in the 2-, 3-, 4-, 5-, and 6-year old E. grandis × E. urophyllas plantations were 86. 01, 90. 51, 133.20, 124. 98, and 97.56 kg ·hm^-2, respectively.