PDF(Pubmed)
Abstract：
Soil seed banks play a central role in vegetation dynamics and may be an important source of ecological restoration. However, the vast majority of seed bank studies examined only the uppermost soil layers (0-10 cm); hence, our knowledge on the depth distribution of seed bank and the ecological significance of deeply buried seeds is limited. The aim of our study was to examine the fine-scale vertical distribution of soil seed bank to a depth of 80 cm, which is one of the largest studied depth gradients so far. Our model systems were alkaline grasslands in East-Hungary, characterised by harsh environmental conditions, due to Solonetz soil reference group with Vertic horizon. We asked the following questions: (1) How do the seedling density and species richness of soil seed bank change along a vertical gradient and to what depth can germinable seeds be detected? (2) What is the relationship between the depth distribution of the germinable seeds and the species traits?
In each of the five study sites, four soil cores (4 cm diameter) of 80 cm depth were collected with an auger for soil seed bank analysis. Each sample was divided into sixteen 5-cm segments by depth (320 segments in total). Samples were concentrated by washing over sieves and then germinated in an unheated greenhouse. Soil penetration resistance was measured in situ next to each core location (0-80 cm depth, 1-cm resolution). We tested the number and species richness of seedlings observed in the soil segments (N = 320), using negative binomial generalized linear regression models, in which sampling layer and penetration resistance were the predictor variables. We ran the models for morphological groups (graminoids/forbs), ecological groups (grassland species/weeds) and life-form categories (short-lived/perennial). We also tested whether seed shape index, seed mass, water requirement or salt tolerance of the species influence the vertical distribution of their seed bank.
Germinable seed density and species richness in the seed bank decreased with increasing soil depth and penetration resistance. However, we detected nine germinable seeds of six species even in the deepest soil layer. Forbs, grassland species and short-lived species occurred in large abundance in deep layers, from where graminoids, weeds and perennial species were missing. Round-shaped seeds were more abundant in deeper soil layers compared to elongated ones, but seed mass and ecological indicator values did not influence the vertical seed bank distribution. Our research draws attention to the potential ecological importance of the deeply buried seeds that may be a source of recovery after severe disturbance. As Vertisols cover 335 million hectares worldwide, these findings can be relevant for many regions and ecosystems globally. We highlight the need for similar studies in other soil and habitat types to test whether the presence of deep buried seeds is specific to soils with Vertic characteristics.
In each of the five study sites, four soil cores (4 cm diameter) of 80 cm depth were collected with an auger for soil seed bank analysis. Each sample was divided into sixteen 5-cm segments by depth (320 segments in total). Samples were concentrated by washing over sieves and then germinated in an unheated greenhouse. Soil penetration resistance was measured in situ next to each core location (0-80 cm depth, 1-cm resolution). We tested the number and species richness of seedlings observed in the soil segments (N = 320), using negative binomial generalized linear regression models, in which sampling layer and penetration resistance were the predictor variables. We ran the models for morphological groups (graminoids/forbs), ecological groups (grassland species/weeds) and life-form categories (short-lived/perennial). We also tested whether seed shape index, seed mass, water requirement or salt tolerance of the species influence the vertical distribution of their seed bank.
Germinable seed density and species richness in the seed bank decreased with increasing soil depth and penetration resistance. However, we detected nine germinable seeds of six species even in the deepest soil layer. Forbs, grassland species and short-lived species occurred in large abundance in deep layers, from where graminoids, weeds and perennial species were missing. Round-shaped seeds were more abundant in deeper soil layers compared to elongated ones, but seed mass and ecological indicator values did not influence the vertical seed bank distribution. Our research draws attention to the potential ecological importance of the deeply buried seeds that may be a source of recovery after severe disturbance. As Vertisols cover 335 million hectares worldwide, these findings can be relevant for many regions and ecosystems globally. We highlight the need for similar studies in other soil and habitat types to test whether the presence of deep buried seeds is specific to soils with Vertic characteristics.
摘要：
土壤种子库在植被动态中起着核心作用，可能是生态恢复的重要来源。然而,绝大多数种子库研究只检查了最上面的土壤层(0-10厘米)；因此，我们对种子库的深度分布和深埋种子的生态意义的认识是有限的。我们研究的目的是检查土壤种子库的精细尺度垂直分布到80厘米的深度，这是迄今为止研究的最大深度梯度之一。我们的模型系统是东匈牙利的碱性草原，以恶劣的环境条件为特征，由于具有Vertic地平线的Solonetz土壤参考组。我们提出了以下问题：（1）土壤种子库的幼苗密度和物种丰富度如何沿垂直梯度变化以及可以检测到发芽种子的深度？（2）发芽种子的深度分布与物种性状之间有什么关系？
在五个研究地点中，用螺旋钻收集四个80厘米深的土壤核心（4厘米直径）用于土壤种子库分析。按深度将每个样品分成16个5cm的片段(总共320个片段)。通过在筛上洗涤来浓缩样品,然后在未加热的温室中发芽。在每个岩心位置(0-80厘米深度,1厘米分辨率）。我们测试了在土壤部分（N=320）中观察到的幼苗的数量和物种丰富度，使用负二项广义线性回归模型，其中采样层和穿透阻力是预测变量。我们运行了形态学组的模型（语法类/forbs），生态组（草地物种/杂草）和生命形式类别（短命/多年生）。我们还测试了种子形状指数，种子质量，物种的需水量或耐盐性会影响其种子库的垂直分布。
种子库的发芽种子密度和物种丰富度随着土壤深度和穿透阻力的增加而降低。然而,即使在最深的土壤层中，我们也检测到了6种9种可发芽的种子。Forbs,草原物种和短命物种大量出现在深层，从零开始，杂草和多年生物种失踪。与细长的种子相比，圆形种子在较深的土壤层中更丰富，但种子质量和生态指标值对种子库的垂直分布没有影响。我们的研究提请注意深埋种子的潜在生态重要性，这些种子可能是严重干扰后恢复的来源。由于Vertisols覆盖全球3.35亿公顷，这些发现可能与全球许多地区和生态系统有关。我们强调需要在其他土壤和栖息地类型中进行类似的研究，以测试深埋种子的存在是否特定于具有Vertic特征的土壤。
在五个研究地点中，用螺旋钻收集四个80厘米深的土壤核心（4厘米直径）用于土壤种子库分析。按深度将每个样品分成16个5cm的片段(总共320个片段)。通过在筛上洗涤来浓缩样品,然后在未加热的温室中发芽。在每个岩心位置(0-80厘米深度,1厘米分辨率）。我们测试了在土壤部分（N=320）中观察到的幼苗的数量和物种丰富度，使用负二项广义线性回归模型，其中采样层和穿透阻力是预测变量。我们运行了形态学组的模型（语法类/forbs），生态组（草地物种/杂草）和生命形式类别（短命/多年生）。我们还测试了种子形状指数，种子质量，物种的需水量或耐盐性会影响其种子库的垂直分布。
种子库的发芽种子密度和物种丰富度随着土壤深度和穿透阻力的增加而降低。然而,即使在最深的土壤层中，我们也检测到了6种9种可发芽的种子。Forbs,草原物种和短命物种大量出现在深层，从零开始，杂草和多年生物种失踪。与细长的种子相比，圆形种子在较深的土壤层中更丰富，但种子质量和生态指标值对种子库的垂直分布没有影响。我们的研究提请注意深埋种子的潜在生态重要性，这些种子可能是严重干扰后恢复的来源。由于Vertisols覆盖全球3.35亿公顷，这些发现可能与全球许多地区和生态系统有关。我们强调需要在其他土壤和栖息地类型中进行类似的研究，以测试深埋种子的存在是否特定于具有Vertic特征的土壤。
