Jing Jingying, Søegaard Karen, Cong Wen-Feng, Eriksen Jørgen
Department of Agroecology, Aarhus University, Tjele, Denmark.
PLoS One. 2017 Jan 3;12(1):e0169208. doi: 10.1371/journal.pone.0169208. eCollection 2017.
Plant species diversity may benefit natural grassland productivity, but its effect in managed grassland systems is not well understood. A four-year multispecies grassland experiment was conducted to investigate the effect of species diversity-legumes and non-leguminous forbs-on productivity, persistence and sward quality under cutting or grazing regimes and with or without slurry application. Three mixtures were established- 3-mix: grass, red and white clover, 10-mix: 3-mix plus birdsfoot trefoil and six non-leguminous forbs, and 12-mix: 10-mix plus lucerne and festulolium. Species diversity increased sward production and yield persistence under cutting regime. The 12-mix had the highest yield from the second year onwards and no statistically significant yield reduction over four years, while annual yields in the 3-mix and 10-mix decreased significantly with increasing grassland age. The higher yield in the 12-mix was mainly due to the inclusion of high-yielding lucerne. The 10-mix and 12-mix had lower proportions of unsown species than the 3-mix, the difference being dependent on grassland age. Generally, the 3-mix had higher concentrations of in-vitro organic matter digestibility (IVOMD), neutral detergent fiber (NDF) and crude protein (CP), and a lower concentration of ash than the 10-mix and 12-mix. Slurry application increased annual yield production by 10% and changed the botanical composition, increasing the proportion of grass and decreasing the proportion of legumes. Compared to cutting, grazing increased forage production by 9% per cut on average and lowered legume and forb proportions in the mixtures, but yields did not differ among the three mixtures. Overall, our results suggest that species diversity increases sward productivity and persistence only under an ungrazed cutting regime. We conclude that increasing species diversity by selecting appropriate species with compatible management is key to achieving both high yields and high persistence in managed grasslands.
植物物种多样性可能有益于天然草原生产力，但其在人工管理草地系统中的作用尚未得到充分了解。开展了一项为期四年的多物种草地试验，以研究物种多样性（豆科植物和非豆科杂草）在刈割或放牧制度下以及有无施用粪肥的情况下对生产力、持久性和草地质量的影响。建立了三种混合物——3种混播组合：禾本科植物、红三叶和白三叶；10种混播组合：3种混播组合加上鸟足豆和六种非豆科杂草；12种混播组合：10种混播组合加上紫花苜蓿和羊茅黑麦草。在刈割制度下，物种多样性提高了草地产量和产量持久性。从第二年起12种混播组合产量最高，且四年内产量无统计学显著下降，而3种混播组合和10种混播组合的年产量随草地年龄增加而显著下降。12种混播组合产量较高主要归因于包含了高产的紫花苜蓿。与3种混播组合相比，10种混播组合和12种混播组合中未播种物种的比例较低，差异取决于草地年龄。总体而言，3种混播组合的体外有机物消化率（IVOMD）、中性洗涤纤维（NDF）和粗蛋白（CP）浓度较高，灰分浓度低于10种混播组合和12种混播组合。施用粪肥使年产量提高了10%，并改变了植物组成，增加了禾本科植物比例，降低了豆科植物比例。与刈割相比，放牧平均每次刈割使牧草产量提高9%，并降低了混合物中豆科植物和杂草的比例，但三种混合物的产量没有差异。总体而言，我们的结果表明，物种多样性仅在非放牧的刈割制度下提高草地生产力和持久性。我们得出结论，通过选择管理方式兼容的合适物种增加物种多样性是在人工管理草地实现高产和高持久性的关键。
