湖南会同连作杉木林凋落物量20年动态特征

Litterfall production and dynamic for twenty years of a successive replanting Cunninghamia lanceolata plantation at Huitong,Hunan

在湖南会同杉木林生态系统国家野外科学观测研究站试验基地的第Ⅲ集水区,对连作杉木林的凋落物量进行连续20a的定位观测,研究凋落物的组成特征、季节和长期动态变化格局。结果表明:连作杉木林从第8年起开始收集到凋落物,第8～20年间,凋落物量总体呈上升趋势,年平均生物量为(1109.86±117.27)kg·hm-2。凋落物中针叶、小枝、落果和碎屑所占比例分别为63.75%,25.87%,5.11%和2.19%。会同杉木人工林有明显的季节性凋落节律,1月至6月份,凋落物量总体上呈现上升趋势,从6月份至12月份总体上呈下降趋势,凋落物量的峰值出现在6月份,11月份则全年最低。凋落物与林龄呈显著的二次曲线相关,模拟凋落物量与林龄的关系,得到二次曲线方程关系:y=-10.06x2+361.1x-1747,R2=0.920,p<0.001。凋落物中的小枝、针叶、落果与林龄呈显著二次曲线方程关系(p<0.05),而碎屑与林龄的相关性不显著。

We have investigated the dynamics of litterfall production and components using 20 year observation data of litterfall production collected in a successive replanting Cunninghamia lanceolata plantation at the third watershed （No. III） in Huitong National Key Forest Ecosystem Station. Results showed that the successive replanting C. lanceolata plantation started to produce litterfall only at the eight year old. During the period from 8 to 20 years, litterfall production increased as the stand grew. The averaged annual amount of litterfall was estimated to be （ 1109.86± 117.27） kg. hm^-2, of which leaves, branches, fruits and chippings accounted for 63.75% , 25.87% , 5. 11% and 2. 19% , respectively. Seasonal change in litterfall was also observed in the successive replanting C. lanceolata plantation. Litterfall amount increased from January to June and then decreased from June to December. The highest value of litterfall occurred in June and the lowest was found in November. Litterfall production （y） was significantly correlated with stand age （x）, which can be quantitatively expressed by the regression equation ： y = - 10.06x^2 ＋ 361. lx - 1747, R^2 = 0. 920, p 〈 0. 001. There was also a conic relationship （p 〈 0.05） between the production of branches, leaves and fruits litterfall and forest age, while the relationships of chippings and forest age were not significant.