南方丘陵人工林林下植物种间关系分析

Interspecific association between understory species in a southern highland plantation

在2×2联列表的基础上,应用χ2检验和联结系数,检测南方丘陵人工林林下植物种间关系,以期分析南方丘陵人工林植被恢复程度及其稳定性.结果表明,灌草两层联结程度达到显著的种对很少;灌木层极显著的有12种对,显著的有19种对,其余200种对联结程度不显著;草本层极显著和显著各有11种对,其余83种对联结程度不显著.按组间联系及种间的正负关联性,灌木层植物可分为2个种组:Ⅰ.四川红淡比、三叶赤楠、乌饭树、满树星、长托菝葜、格药柃;Ⅱ.大叶胡枝子、白马骨、牡荆.种组Ⅰ与种组Ⅱ之间许多种群间存在显著负关联.优势种往往在种间关系中起着关键作用.草本层优势种狗脊蕨、暗鳞鳞毛蕨、扇叶铁线蕨之间存在极显著正关联,且与多种群存在极显著或显著正关联;灌木层中2个种组均以优势种为联结核心.灌草层中正负关联的比例反映了灌木层和草本层物种处在动态变化中.灌木层正负关联比例为125/106,草本层42/63.最后分析了种间联结方法的几个缺陷,并对该方法的使用提出建议.

Based upon 2 × 2 contingency table, X^2 test and association coefficient were used to determine the interspecific association between understory species in a southern highland plantation, and to analyze the restoration degree and the stability of southern highland vegetations originated from plantation. The Qianyanzhou in Taihe County of Jiangxi Province, a typical sample of southern highland plantation, was chosen to make the study. The results showed that both in shrub layer and in herb layer, species pair with X^2 reaching significant level（P 〈 0.05 ） was few in number. In shrub layer, 12 species pairs＇ association was highly significant（P 〈 0.01 ）, 19 pairs＇ was significant（ P 〈 0.05）, and other 200 pairs＇ was nonsignificant, while in herb layer, 11 pairs＇ was highly significant, 11 pairs＇ was significant and other 83 pairs＇ was nonsignificant. According to interspecific association and correlation, shrub layer was divided into two species groups： Group Ⅰ . Adinandra bockiana, Syzygium grijsii, Vaccinium bracteatum, Ilex aculeolata, Smilax ferox, Eurya muricata and Group Ⅱ . Lespedeza davidii, Serissa serissoides, Vitex negundo var. cannabifolia. Many species in Group Ⅰ had a significantly negative association with the species in Group Ⅱ , and dominant species always played a key role in the relationships among species. The three dominant species in herb layer, Woodwardia japonica, Dryopteris atrata and Adiantum flabellulatum, had a highly significant positive correlation between each other, and moreover, had a significant or highly significant positive association with many other herbaceous species. Similarily, dominant species in shrub layer played a key role on the interspecific association in the two species groups. The ratios of positive and negative association indicating the species compositions of the two layers were fluctuating, which was 125/106 in shrub layer and 42/ 63 in herb layer. Several shortcomings of interspecific association method were pointed out, with some proposals put forward.