Data from: Seed source impacts germination and early establishment of dominant grasses in prairie restorations

Land managers choose seed from a variety of provenances for restoration projects. By selecting seed of the local ecotype, managers can increase establishment in the short term and prevent the disruption of local adaptations and genetic swamping in the long term. However, local seed may be disadvantageous if populations are inbred or maladapted to managed restoration environments. Seed selection may be further confounded by propagation methods. Three dominant C4 grasses, Andropogon gerardii, Bouteloua curtipendula and Sorghastrum nutans, from three types of seed provenances (remnant, restoration and nursery) were planted as seeds and plugs into experimental plots at three established tallgrass prairie restorations in western Minnesota, USA. Using a common garden design, we tested whether (i) provenance and (ii) site of planting influence germination and first-season survival and growth both (iii) for seeds directly planted in the field and for transplants (plugs). Seed provenance impacted germination and seedling survival in all cases, except S. nutans seeded directly in the field. Andropogon gerardii and B. curtipendula nursery seedlings were consistently taller than those of the other provenance types. When directly seeded, germination, survival and vigour differed among restoration sites; however, the results were species specific. Sorghastrum nutans germination varied among sites depending on provenance, indicating that this species may be particularly sensitive to environmental conditions. Germination was 3–12 times greater for plugs than for seeds directly planted in the field in summer, but mortality after planting in the field was low for both groups. Synthesis and applications. Provenance and restoration site had varying effects among species, indicating that the dominant C4 grasses used in this study ought not to be considered ecological equivalents. While we found little evidence of local adaptation, use of local remnant seeds diminishes the risk of spreading maladapted genotypes. Germination limited establishment when sowing seeds directly in summer. Supplemental use of plugs may increase species diversity in restorations.土地管理者会从多种种源（provenance）中遴选种子，用于生态修复项目。通过选用本地生态型（ecotype）的种子，管理者可在短期内提升幼苗定植成功率，并在长期防止本地适应性被破坏以及遗传淹没（genetic swamping）。然而，若种群存在近交或无法适应人工修复的生境，本地种子则可能存在劣势。种子遴选流程还可能因繁殖方式的差异而变得更为复杂。 本研究选取了3种优势C4草本植物（C4 grasses）：大须芒草（Andropogon gerardii）、垂穗草（Bouteloua curtipendula）以及拟高粱（Sorghastrum nutans），其种子分别来自3类种源：遗留种群种源、修复地种源与苗圃种源。研究将这些材料以种子与穴盘苗（plugs）两种形式，种植于美国明尼苏达州西部3处已建成的高草草原修复样地的实验小区中。 本研究采用同质园实验设计（common garden design），针对（1）种源与（2）种植位点对发芽率、第一季存活率与生长量的影响展开测试，分别覆盖直接田间播种的种子以及移栽穴盘苗两种材料。除直接田间播种的拟高粱外，种源对所有处理组的发芽率与幼苗存活率均存在显著影响。大须芒草与垂穗草的苗圃育苗幼苗，其株高始终高于其他种源来源的幼苗。 直接播种组的发芽率、存活率与幼苗活力在不同修复样地间存在差异，但该结果具有物种特异性。拟高粱的发芽率随种植位点与种源的不同而发生变化，表明该物种对环境条件尤为敏感。夏季种植时，穴盘苗的发芽率是直接田间播种种子的3至12倍，但两组材料的田间定植后死亡率均较低。 研究总结与应用启示：种源与修复样地对不同物种的影响存在差异，表明本研究所使用的几种优势C4草本植物不应被视为具有等同的生态功能。尽管本研究未发现显著的本地适应性证据，但使用本地遗留种群种子可降低传播不良适应基因型的风险。夏季直接播种时，发芽率是限制幼苗定植的关键因素。辅助使用穴盘苗可提升生态修复项目中的物种多样性。