Quantitative genetic traits of eight grassland species from three regions of Germany (Schwäbische Alb, Hainich-Dün, Schorfheide Chorin)

This study was carried out within the Biodiversity Exploratories (www.biodiversity-exploratories.de), a large-scale and long-term project for investigating relationships between land use, biodiversity and ecosystem processes (Fischer et al. 2010, doi: 10.1016/j.baae.2010.07.009). The core of this project is a network of standardized field plots in grasslands and forests in three different regions of Germany - Schwäbische Alb, Hainich-Dün and Schorfheide-Chorin. Within each region, there are 50 grassland plots covering a wide range of land-use types and intensities. The aim of our study was to test how differences in land use generate genetic differences among populations across multiple regions and grassland species, and thus to assess how common and how consistent evolutionary responses to land use are in grassland plants, which land-use factors contribute most to genetic differentiation, and which plant traits are most responsive. We studied eight grassland species that occurred in all three regions and all land-use types, with 23 to 108 populations per species. In the summer of 2008, we visited all 150 grassland plots in the three regions three times (in June, July, August) and collected mature seeds in all plots where the species occured. We germinated the seeds of all maternal families of all species and transplanted one seedling from each of 10 maternal families per population and species separately into pots in a common garden. During plant growth we measured several traits. We recorded flowering phenology, defined as the time when the stamina were visible on grasses and when the first flower opened on herbs. We harvested plant aboveground biomass at the time of seed maturity. For each plant, we also determined the maximum plant height as the length of the longest tiller or stem, and we counted the total number of inflorescences or flowers. We then separated aboveground biomass into vegetative parts (tillers or stems) and reproductive parts (inflorescences or flowers), dried all biomass samples and weighed them. We calculated total aboveground biomass as the sum of vegetative and reproductive mass, and reproductive allocation as the ratio between reproductive and total aboveground biomass.

本研究依托于生物多样性探索计划（Biodiversity Exploratories，网址：www.biodiversity-exploratories.de）开展，该计划是一项用于探究土地利用、生物多样性与生态系统过程之间关联的大型长期研究项目（Fischer等，2010，doi: 10.1016/j.baae.2010.07.009）。该项目的核心是在德国三个不同区域——施瓦本阿尔卑斯（Schwäbische Alb）、海尼希-敦（Hainich-Dün）以及肖夫海德-乔林（Schorfheide-Chorin）——的草地与森林中构建的标准化样地网络，每个区域内设有50个草地样地，覆盖了广泛的土地利用类型与利用强度。本研究的目标在于检验土地利用差异如何在多个区域及多种草地物种的种群间催生遗传分化，以此评估草地植物对土地利用的进化响应具有怎样的普遍性与一致性，明确对遗传分化贡献最大的土地利用因子，以及响应最为显著的植物性状。本次研究选取了在三个区域及所有土地利用类型中均有分布的8个草地物种，每个物种拥有23至108个种群。2008年夏季，我们分别于6月、7月、8月三次走访三个区域的全部150个草地样地，并在各物种分布的样地中采集成熟种子。随后，我们对所有物种的所有母本家系（maternal family）种子进行萌发，将每个种群、每个物种的10个母本家系各选取一株幼苗，移栽至共同花园（common garden）的花盆中。在植物生长阶段，我们测定了多项性状：记录开花物候，其中禾本科植物以雄蕊可见的时间为标准，草本植物以首朵花开放的时间为标准；在种子成熟时收获地上生物量；测定每株植物的最大株高（以最长分蘖或茎秆的长度计），并统计总花序或花朵数量。随后将地上生物量划分为营养器官（分蘖或茎秆）与生殖器官（花序或花朵），将所有生物量样品烘干后称重，通过营养器官与生殖器官生物量之和计算总地上生物量，以生殖器官生物量与总地上生物量的比值计算生殖分配。