海南铜鼓岭灌木林稀疏规律

The thinning regular of the the shrubbery at Tongguling National Nature Reserve on Hainan Island,China

以海南省文昌市铜鼓岭国家级自然保护区160m×160m的山麓灌木林固定样地中胸径(DBH)"1.5cm的所有木本植物为对象,并根据DBH划分为7个径级,研究其稀疏规律,结果表明:1)群落中Ⅰ级(DBH<4.5cm)个体数所占百分比最大,占64%,群落结构为"倒J型",林分密度是幼树>小树>成年树,该群落正处于稳定状态,且个体间为争夺更多的生存空间和资源发生强烈的自疏和它疏作用,存在明显的稀疏现象。2)各径级地上生物量随着密度增加呈幂函数增加,幂函数方程为:AGB=6×107N0.4626或lnAGB=0.4626lnN+17.855,在较小的密度范围内,随林分密度的增加,群落地上总生物量增加较快,但当密度趋于0.6株/m2时,地上生物量变化缓慢,趋于恒定值。3)林分密度与各径级平均胸径呈负相关关系(密度越大,平均胸径越小),其幂函数关系式为:N=70.1d-3.5506,R2=0.8808。4)选择Yoda提出的幂函数方程对天然灌木林自然稀疏规律进行模拟,林分密度与平均生物量之间具有显著相关性,其关系式为:W=2219.1N-0.5374或lnW=7.7048-0.5374lnN;稀疏指数α值为0.5374,这与Yoda所提出的3/2指数相差甚远,并不满足-3/2自疏定律。5)此次调查的物种有常见种(0.2hm2样地中个体数≥5的种为常见种)41种,非常见种53种。天然灌木林在物种层面的稀疏也存在一定的规律。

Woody plants with its DBH ≥ 1.5cm at a 160× 160m shrubbery permanent forest plot at Tongguling National Nature Reserve in Wenchang, Hainan, have been investigated., and those plants have been classified into 7 size classes based on DBH to determine the regulation of Thinning. Results showed that： 1 ） ClassⅠI （DBH 〈 4.5cm） occupied a maximum percentage （64%）. The community was ＂Inverse- J type＂, the order of stands density was young trees 〉 small trees〉 grow-up trees, the community was in a stable state. It has a typical phenomenon of thinning caused by the self- thinning and alien-thinning which caused by the individuals to compete for more living space and resources. 2 ） Above ground biomass of each classes increased with the growth of density, in a small density range, above ground biomass increased swiftly with the growth of density, but changed slowly and tended to a constant value when the density tend to be 0.6 plant per square meter, and the power function equation was AGB = 6× 107N0.4626 or lnAGB = 0.46261nN＋ 17.855. 3） Ithad a negative correlation between the density and the average DBH of each class （larger the density, smaller the average DBH） and its power function equation was ： N = 70.1 d-3550, R2= 0.8808. 4） We simulated the sel-thinning law put forward by Yoda, and found that there was a significant coherence between stand density and average biomass, the correlation was： W= 2219.1N-0.5374 or lnW= 7.7048-0.53741nN, thinning index a value was 0.5374, it was largely differ from the 3/2 index put forward by Yoda,did not satisfy the -3/2 law of self-thinning. 5） 41 common species （individuals more than or equals 5 per 0.2hm2 ） and 51 rare species have been investigated. It has a certain discipline in terms of thinning of species of natural shrubbery.