亚热带-温带过渡区秦岭落叶阔叶林幼苗组成及数量动态研究

以秦岭落叶阔叶林25 hm²固定样地的木本植物幼苗为研究对象，于2015-2019年对幼苗种类、数量、萌发和死亡情况进行调查，并对幼苗的物种组成、数量及动态特征进行分析。结果显示：5年间调查到的幼苗分属24科42属，共69个物种，累计记录11 408株；样地中的树种组成和优势树种组成基本不变，但整体物种数有减少趋势；幼苗数量在年际间和不同物种间有较大差异，17个物种幼苗数量较多，大于100株，其总和占幼苗总量的56.28%,产生新增幼苗的物种有53个，累计增加6280株；死亡幼苗6929株，其中4469株为新生幼苗，占新增幼苗总数的74.14%,新苗的死亡数远远大于旧苗死亡数；幼苗新增和死亡的高峰期大致吻合，出现在每年的5-7月。整体看来，秦岭大样地的幼苗数量处于平稳波动状态，物种更新较为稳定。

Seedling composition and dynamics of a deciduous broad-leaved forest in the subtropical-temperate transitional zone of the Qinling Mountains,China

We investigated the species, quantity, germination, and mortality of woody seedlings in a 25 hm² broad-leaved deciduous forest plot in the Qinling Mountains of China from 2015 to 2019 and analyzed the species composition and dynamic characteristics of seedlings. Results identified 69 species belonging to 42 genera and 24 families, including a total of 11 408 seedlings (2015 to 2019). There was little change in species composition and dominant species composition in the plot, but species number decreased overall. Seedling numbers varied significantly among different tree species across years, including 17 species with more than 100 individuals (accounting for 56.28%) and 53 species with new seedlings. In total, there were 6280 recruited seedlings, 6929 dead seedlings, and 4469 new seedlings, accounting for 74.14% of the total number of recruited seedlings. The mortality of newly recruited seedlings was much higher than that of old seedlings. Peak seedling growth and mortality roughly occurred from May to July each year. The number of seedlings in the plot fluctuated steadily, and species regeneration was relatively stable.