作 者 ：郭华,王孝安*,朱志红
期 刊 ：生态学报 2010年 30卷 23期 页码：6521~6529
Keywords:Quercus wutaishanica, seed sowing experiment, seed limitation, microsite limitation,
摘 要 ：辽东栎(Quercus wutaishanica)是子午岭地区的乡土乔木树种，也是该地区气候顶极群落的建群种，其幼苗的补充更新影响着森林群落的结构及物种组成。在3种典型生境（辽东栎林、人工油松林、灌草丛）中，设置3因素（种子、干扰、遮荫）两水平的野外播种实验（随机区组设计），记录辽东栎幼苗出苗量，并监测幼苗同生群在3种生境中3a间的生长状况，以确定种子及微生境在辽东栎幼苗补充过程中的限制作用。播种实验样方大小30 cm×30 cm，共计216个样方。结果显示，在辽东栎林及油松林内，增加种子和干扰强度（去除枯落物），能引起出苗量和幼苗补充量的显著增加，且2种处理方式间存在交互作用，表明在郁闭林冠下，辽东栎幼苗的补充受到了种子和微生境的双重限制，枯落物是导致微生境限制的主要因素之一。在灌草丛生境，各种处理方式均不能增加幼苗的补充量，表明辽东栎无法在开阔生境（强光照、干旱）中完成实生幼苗的补充更新。3种生境中的幼苗同生群生存分析表明，辽东栎幼苗在森林群落中存活率显著高于灌草丛群落。根据幼苗生长指标判断，在3种生境中，人工油松林是辽东栎幼苗定居的最佳场所。与实验预期相反，灌木对辽东栎幼苗的补充无显著影响。
Abstract:An important task of plant population ecology is to understand what factors affect seedling recruitment, such as seed and microsite availability. Sowing experiments, i.e. seed addition into existing populations (augmentation experiments) or seed introduction into unoccupied habitats (introduction experiments), may provide unambiguous evidence for different types of limitation, such as seed or microsite availability limitation. Liaodong oak (Quercus wutaishanica), an endemic woody species, is a dominant species of the forest community in Mt. Ziwuling, but it has low natural regeneration rates and recruitment from acorns is difficult. In order to determine whether seedling recruitment in Q. wutaishanica is limited by seed availability, microsite availability, or both, a field sowing experiment was performed in 216 plots (30 cm×30 cm) in three typical stands (Liaodong oak forest, conifer plantation, and grassland, 72 plots per stand). The seed addition, disturbance (removing the litter) and shrub cover were selected as influencing factors. The numbers of emerged seedlings were tagged and monitored from April 2007 to October 2009. Light, soil moisture, and growth parameters (height, stem basal diameter and the wormholes per leaf) were measured bimonthly from April to October every year. Seedling data (number of oak seedlings per plot) in every stand were log-transformed to approximate normality. The effects of three treatments were analyzed with GLM Multivariate in SPSS version 13.0. The effects of treatments (seed addition and disturbance) on the number of recruited seedlings, variation of seedling growth across different years, and differences in light intensity and soil moisture among three stands were analyzed by One-Way ANOVA (Tukey HSD multiple comparison test). The results showed that, in the oak forest, leaf wormholes were significantly more numerous than in the conifer forest and the grassland. In the conifer forest, stem basal diameter was significantly higher than in the oak forest and the grassland. Furthermore, We found that seed addition and disturbance always significantly increased seedling emergence and recruitment in oak and conifer forests. There was an interaction between seed addition and disturbance. We demonstrated that recruitment of Q. wutaishanica seedlings was limited by seed and microsite availability in closed forests. Litter is one of the factors leading to microsite limitation in oak and conifer forests. However, in grassland, no treatment could improve oak recruitment, indicating that the open site was not suitable for seedling recruitment because of intense light and soil drought. It was also found that the survival rate of Liaodong oak seedling was significantly higher in forests than in grassland and that the conifer plantation was safer for seedling establishment according to the seedling growth in the three forest stands. Unexpectedly, shrub cover did not affect the recruitment of Liaodong oak seedlings. To conclude, we suggest that lack of viable seeds and suitable habitat are the main limiting factors for Q. wutaishanica recruitment in this region, and conifer plantation is the most suitable habitat for oak seedling survival. In early successional grasslands, Liaodong oak is unlikely to recruit successfully regardless of manipulations. We suggest that co-limitation by seed and microsite availability underlies the mechanism of Q. wutaishanica population recruitment.
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