Extensively managed grasslands in temperate biomes are capable of harboring a big variety of plant and invertebrate species. Yet, they have suffered from a strong decline in the past decades mainly due to agricultural intensification. Agri-environment schemes have been introduced in Europe in order to promote farmland biodiversity, but they were only little effective, especially so in grasslands. Not surprisingly, grassland restoration and recreation through active seed addition has thus gained in importance in the recent years. The most common methods used rely either on the addition of commercial seed mixes, on the addition of seeds collected from a speciose donor grassland or on transferring hay from a speciose donor grassland after the soil of the receiver site has been prepared (ploughing, harrowing or topsoil removal). While there is evidence that these restoration methods may contribute to improve the biodiversity of grasslands, especially plant diversity, their relative effectiveness remains poorly known. The aim of this systematic review is to scrutinize the peer-reviewed literature for scientific evidence about comparative effectiveness. We will search for peer-reviewed journal articles in bibliographic databases and grey literature in search engines and organizational websites dealing with at least one of the above mentioned seed addition methods. We will only include studies which were carried out in temperate Europe. Through a scoping exercise a search string was developed which was based on a previously prepared test-list. The search string was then tested for validity with two independent reference lists. Screening will be done on the title, abstract and full-text level and consistency checking will be done on a random subsample by a second reviewer. After critically appraising internal validity of the retained studies, data on the responses of plants and invertebrates as well as all relevant meta-data will be extracted and coded. A meta-analysis will be conducted on studies with high internal validity whereas a narrative analysis will be done with descriptive statistics on studies with medium internal validity. Potential effect modifiers like study duration, former land use or local climate will be included in the analysis as moderators.

中文翻译：

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种子添加方法在恢复或重建物种丰富的草原方面的相对有效性：系统评价方案

温带生物群落中被广泛管理的草原能够容纳各种植物和无脊椎动物。然而，由于农业集约化，它们在过去几十年遭受了严重的衰落。为了促进农田生物多样性，欧洲已经引入了农业环境计划，但是这些计划效果不佳，尤其是在草原上。毫不奇怪，近年来，通过积极添加种子来恢复和重建草原已经变得越来越重要。使用的最常见方法取决于添加商业种子混合物，添加从特定供体草地收集的种子或准备好接收者土壤后（从犁地，耙地或表土清除）。尽管有证据表明这些恢复方法可能有助于改善草原的生物多样性，尤其是植物多样性，但其相对有效性仍然知之甚少。本系统综述的目的是对经过同行评审的文献进行审查，以获取有关比较有效性的科学证据。我们将在书目数据库中搜索经过同行评审的期刊文章，并在搜索引擎和组织网站中搜索涉及至少一种上述种子添加方法的灰色文献。我们将只包括在温带欧洲进行的研究。通过范围界定练习，开发了基于先前准备的测试列表的搜索字符串。然后使用两个独立的参考列表对搜索字符串进行有效性测试。筛选将在标题上进行，摘要和全文级别以及一致性检查将由第二位审阅者对随机子样本进行。在严格评估保留研究的内部有效性之后，将提取和编码有关植物和无脊椎动物反应的数据以及所有相关的元数据。对具有较高内部效度的研究进行荟萃分析，对具有中等内部效度的研究进行描述性统计分析。诸如研究持续时间，以前的土地使用或当地气候等潜在效应修正因子将作为主持人纳入分析。有关植物和无脊椎动物反应的数据以及所有相关的元数据都将被提取和编码。对具有较高内部效度的研究进行荟萃分析，对具有中等内部效度的研究进行描述性统计分析。诸如研究持续时间，以前的土地使用或当地气候等潜在效应修正因子将作为主持人纳入分析。有关植物和无脊椎动物反应的数据以及所有相关的元数据都将被提取和编码。对具有较高内部效度的研究进行荟萃分析，对具有中等内部效度的研究进行描述性统计分析。诸如研究持续时间，以前的土地使用或当地气候等潜在效应修正因子将作为主持人纳入分析。