Seed bank densities across an environmental gradient.

We determined the distribution of seed bank densities of woody perennial species across 5 permanent vegetation plots. We found that the distribution of seeds in the soil was determined by the spatial location of parent trees at all sites, but that absolute densities varied significantly between plots. Densities of viable seeds in soil was determined across five permanent vegetation plots, in 4 years. Soil cores were taken to 2 inches deep (including litter), soil was stratified at 4 degrees C for 6 weeks, spread out over sterile potting soil, and left in the greenhouse with plenty of light and water. Seedlings were censused as they emerged, censuses continued for 8 mo. Each soil core is 3.5 inches in diameter.本研究针对5个永久性植被样地，明确了多年生木本植物种子库（seed bank）密度的空间分布格局。研究发现，所有样地的土壤种子分布均由母树的空间位置决定，但各样地间的绝对种子密度存在显著差异。本研究历时4年，对上述5个永久性植被样地内的土壤有活力种子密度进行了测定。实验过程中，采集深度为2英寸（包含枯落物层）的土壤土芯，单个土芯直径为3.5英寸；将采集的土壤样品置于4℃条件下层积处理6周后，平铺于无菌盆栽基质中，放置于光照与水分充足的温室内培养。待幼苗萌发后即开展定期统计，持续统计时长为8个月。