Department of Landscape Ecology, Institute for Natural Resource Conservation, Kiel University, Kiel, Germany.
PLoS One. 2021 Feb 2;16(2):e0246459. doi: 10.1371/journal.pone.0246459. eCollection 2021.
Jacobaea vulgaris Gaertn. or common ragwort is a widespread noxious grassland weed that is subject to different regulation measures worldwide. Seedling emergence and growth are the most crucial stages for most plants during their life cycle. Therefore, heterospecific grass or conspecific ragwort litter as well as soil-mediated effects may be of relevance for ragwort control. Our study examines the effects of conspecific and heterospecific litter as well as ragwort conditioned soil on seedling emergence and growth. We conducted pot experiments to estimate the influence of soil conditioning (with, without ragwort), litter type (grass, ragwort, grass-ragwort-mix) and amount (200 g/m², 400 g/m²) on J. vulgaris recruitment. As response parameters, we assessed seedling number, biomass, height and number of seedling leaves. We found that 200 g/m² grass litter led to higher seedling numbers, while litter composed of J. vulgaris reduced seedling emergence. Litter amounts of 400 g/m² had negative effects on the number of seedlings regardless of the litter type. Results for biomass, plant height and leaf number showed opposing patterns to seedling numbers. Seedlings in pots treated with high litter amounts and seedlings in ragwort litter became heavier, grew higher and had more leaves. Significant effects of the soil conditioned by ragwort on seedling emergence and growth were negligible. The study confirms that the amount and composition of litter strongly affect seedling emergence and growth of J. vulgaris. Moreover, while conspecific litter and high litter amounts negatively affected early seedling development in ragwort, those seedlings that survived accumulated more biomass and got taller than seedlings grown in heterospecific or less dense litter. Therefore, ragwort litter has negative effects in ragwort germination, but positive effects in ragwort growth. Thus, leaving ragwort litter on pastures will not reduce ragwort establishment and growth and cannot be used as management tool.
普通豚草（Jacobaea vulgaris Gaertn.）是一种广泛分布的有害草原杂草，在世界范围内受到不同的监管措施的限制。幼苗的出现和生长是大多数植物在其生命周期中最关键的阶段。因此，同种或异种的杂草或豚草凋落物以及土壤介导的效应可能与豚草的控制有关。我们的研究调查了同种和异种凋落物以及豚草条件土壤对幼苗出现和生长的影响。我们进行了盆栽实验，以估计土壤条件（有无豚草）、凋落物类型（草、豚草、草-豚草混合物）和数量（200 克/平方米、400 克/平方米）对普通豚草繁殖的影响。作为响应参数，我们评估了幼苗数量、生物量、高度和幼苗叶片数量。我们发现，200 克/平方米的草凋落物导致了更高的幼苗数量，而由普通豚草组成的凋落物则减少了幼苗的出现。无论凋落物类型如何，400 克/平方米的凋落物数量都对幼苗数量产生了负面影响。生物量、植物高度和叶片数量的结果与幼苗数量呈现相反的模式。处理过大量凋落物的盆栽中的幼苗和豚草凋落物中的幼苗变得更重、更高、叶片更多。受豚草条件的土壤对幼苗出现和生长的显著影响可以忽略不计。该研究证实，凋落物的数量和组成强烈影响普通豚草幼苗的出现和生长。此外，虽然同种凋落物和大量凋落物对豚草的早期幼苗发育产生负面影响，但那些在异种或密度较低的凋落物中存活下来的幼苗积累了更多的生物量，长得更高，比在同种或高密度凋落物中生长的幼苗更高。因此，豚草凋落物对豚草的发芽有负面影响，但对豚草的生长有积极影响。因此，在牧场上留下豚草凋落物不会减少豚草的建立和生长，也不能作为管理工具。
