杉木与阔叶树混交试验初报

 在高明县国营云涌林场以3:1的混交比例，分别营造杉木(Cunninghamia lanceolata)与红荷木(Schima wallichii)、木荷(Schima superba)、火力楠(Michelia macclurei)3种混交林，经过6年的调查观测表明：混交3年后种间关系开始激化，6年以前要适时修枝、截顶、间伐，调整1—2次种间关系。混交林与纯林比较：0—30cm土层养分消耗较大，但林分生物量高，有较高的林分生产率；6年生的混交林枯落物量及其养分元素含量、含水量比纯林大；0—10cm表层N、P、K含量有增加趋势。这些混交类型，宜从现有的3:1比例，扩大至4:1或5:1，尤以杉木+火力楠的类型值得推广。

PRELIMINARY REPORT ON THE MIXED FORESTS OF CUNNINGHAMIA LANCEOLATA WITH THREE KINDS OF BROAD-LEAVED TREES

Cunninghamia lanceolata trees were mixed with Schima wallichii, Schima superba and Michelia macclurei, respectively, to examine the effect of mixing type (tree species composition) and mixing mode (species ratio) on soil fertility in the Yunyong Forest Station of Gaoming County, Guangdong Province. These forests were investigated for 6 consecutive years after planting. The results showed that interspecific competition started to appear after the trees were planted for three years. Twig-trimming, top-pruning, and selective lopping, at least once or twice before the trees were 6 years old, were required to regulate the interspecific relationship, hence weakening the competition between species. In comparison with the pure forest stands, the mixed forests removed more nutrients from the soil, as indicated by a decline in the concentrations of major nutrient elements (N, P, K) in the top 30 cm soil, and had higher biomass and productivity. After 6 years, the litterfall and nutrients in the litter began to increase. Moreover, the mixed forests had higher soil moisture content, and higher total and available N, P, K concentrations in the top soil (0--10cm) than the pure stands. We recommend that the mixing ratio between Cunninghamia lanceolata and broad-leaved tree species be increased from 3:1 to 4:1 or 5:1.