绵阳官司河流域主要森林类型凋落物含量及动态变化

对绵阳官司河流域代表性森林——桤柏混交林、柏木纯林、松栎混交林和松柏混交林的凋落物量、组成特征和季节动态变化及其凋落物中N、P、K含量进行了定位观测和研究，结果表明：其年均凋落物量分别为4．229（3．732—4．828）、5．133（4．215—6．545）、5．701（5．133—6．642）t·hm^-2和5．351（4．762—5．854）t·hm^-2；叶、枝、花果、松皮和杂物的比例分别为72．1：8．9：11．9：0：7．1、75．4：9．0：9．0：0：6．5、79．7：11．0：6．3：0．5：2．4和60．4：9．5：16．0：7．5：6．5；灌木凋落量分别占总凋落量的16．4％、1．5％、9．5％和12．1％；凋落物的年变化规律为：桤柏混交林和柏木林主要集中在生长季，松柏混交林为双峰型，出现在生长季早期和休眠期，松栎混交林为单峰型，为12月份；凋落物中N、P、K元素含量以N素最高，其次是K素，P素最少，N、P、K总量分别为62．702、70．596、79．228kg·hm^-2a^-1和80．011kg·hm^-2·a^-1。

The litterfall of major forests in Guansi River Watershed in Mianyand City, Sichuan Province

The amount, composition, seasonal pattern of litterfalls and its nitrogen, phosphor and potassium contents in four typical forests (i.e. Alnus-Cupressus mixed forest (A.C.), Cupressus funebris forest (C.P.), Pinus massoniana-Quercus mixed forest (P.Q.) and P. massoniana-C.funebris mixed forest (P.C.) ) were measured in Guansi River Watershed in Mianyang Citiy. The results showed that the mean annual litterfall productions were 4.229,5.133,5.701, 5.351 t hm^-2, respectively. The litterfall in A.C. forest was composed of 72.1% of leaves, 8.9% of branches, 11.9% of flowers and fruits and 7.1% of other mixed-matter. In C.P. forest the litterfall of leaves, branches, flowers and fruit, and others amounted to 75.4%, 9.0%, 9.0% and 6.5% of total litterfall. In P.Q. forests the component of litterfall was 79.7%, 11.0%, 6.3%, 0.5% and 2.4% for the leaves, branches, flowers and fruit, pine bark, and others, respectively. These were 60.4%, 9.5%, 16.0%, 7.5% and 6.5% in P.C. forests. The litterfall productions of shrub accounted to 16.4% and 1.5% and 9.5% and 12.1% of total litterfall of the correspondent forests, respectively. The seasonal patterns of litterfall productionyaried with the different stands. The litterfall production peaked at the earlier of growing season and dormancy for P.C. stands, and in December for P.Q. stands. The nitrogen content in litterfall was highest followed by potassiom and phosphor. The amount of N, P and K in litterfall was measured at 62.702, 70.596, 79.228, 80.011 kg•hm^-2•a^-1 in 2003, respectively.