Saatkamp Arne, Affre Laurence, Dutoit Thierry, Poschlod Peter
Institut Méditerranéen d'Ecologie et de Paléoécologie IMEP IRD UMR CNRS 6116, Université d'Aix-Marseille III, FST Saint-Jérôme, case 462, F-13397 Marseille Cedex 20, France.
Ann Bot. 2009 Sep;104(4):715-24. doi: 10.1093/aob/mcp148. Epub 2009 Jun 23.
Seed survival in the soil contributes to population persistence and community diversity, creating a need for reliable measures of soil seed bank persistence. Several methods estimate soil seed bank persistence, most of which count seedlings emerging from soil samples. Seasonality, depth distribution and presence (or absence) in vegetation are then used to classify a species' soil seed bank into persistent or transient, often synthesized into a longevity index. This study aims to determine if counts of seedlings from soil samples yield reliable seed bank persistence estimates and if this is correlated to seed production.
Seeds of 38 annual weeds taken from arable fields were buried in the field and their viability tested by germination and tetrazolium tests at 6 month intervals for 2.5 years. This direct measure of soil seed survival was compared with indirect estimates from the literature, which use seedling emergence from soil samples to determine seed bank persistence. Published databases were used to explore the generality of the influence of reproductive capacity on seed bank persistence estimates from seedling emergence data.
There was no relationship between a species' soil seed survival in the burial experiment and its seed bank persistence estimate from published data using seedling emergence from soil samples. The analysis of complementary data from published databases revealed that while seed bank persistence estimates based on seedling emergence from soil samples are generally correlated with seed production, estimates of seed banks from burial experiments are not.
The results can be explained in terms of the seed size-seed number trade-off, which suggests that the higher number of smaller seeds is compensated after germination. Soil seed bank persistence estimates correlated to seed production are therefore not useful for studies on population persistence or community diversity. Confusion of soil seed survival and seed production can be avoided by separate use of soil seed abundance and experimental soil seed survival.
种子在土壤中的存活有助于种群的延续和群落的多样性，因此需要可靠的方法来衡量土壤种子库的持久性。有几种方法可用于估计土壤种子库的持久性，其中大多数是通过统计从土壤样本中萌发的幼苗数量来进行的。然后，根据季节性、深度分布以及在植被中的存在情况（或不存在情况），将一个物种的土壤种子库分为持久性或短暂性，通常综合为一个寿命指数。本研究旨在确定从土壤样本中统计的幼苗数量是否能得出可靠的种子库持久性估计值，以及这是否与种子产量相关。
从耕地采集的38种一年生杂草种子埋入田间，并每隔6个月通过发芽试验和四唑盐试验检测其活力，持续2.5年。将这种直接测量土壤种子存活的方法与文献中的间接估计方法进行比较，后者利用从土壤样本中幼苗的出土情况来确定种子库的持久性。利用已发表的数据库来探究繁殖能力对基于幼苗出土数据的种子库持久性估计值影响的普遍性。
在埋藏实验中，一个物种的土壤种子存活情况与其基于已发表数据（利用从土壤样本中幼苗出土情况）得出的种子库持久性估计值之间没有关系。对已发表数据库中的补充数据进行分析后发现，虽然基于从土壤样本中幼苗出土情况得出的种子库持久性估计值通常与种子产量相关，但通过埋藏实验得出的种子库估计值却并非如此。
这些结果可以用种子大小与种子数量的权衡来解释，这表明较小种子数量较多在萌发后得到了补偿。因此，与种子产量相关的土壤种子库持久性估计值对于种群延续或群落多样性研究并无用处。通过分别使用土壤种子丰度和实验土壤种子存活率，可以避免混淆土壤种子存活情况和种子产量。
