Department of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova, Viale dell'Università 16, 35020 Legnaro, PD, Italy.
Sci Total Environ. 2019 Feb 15;651(Pt 2):3090-3098. doi: 10.1016/j.scitotenv.2018.10.192. Epub 2018 Oct 15.
Semi-natural grasslands are of great importance to European biodiversity. Their restoration in mountain regions often presents specific problems of raw soil stabilisation and difficult climatic conditions. Methods used to tackle these problems include increasing sowing density and fertilisation. However, past studies were performed at only one site or for a short time and do not clearly show how site traits and time affect restoration results. In six field experiments undertaken on raw soils in the Italian Alps, the effects of sowing density, fertilisation, soil, and climate on the development over time of plant density and cover were analysed over three to six years. The seed was collected from nearby grasslands and sown at rates of 335-21,410 seeds m. During the first one-two years, the percentage of seeds producing established plants at low seed rates was higher in stonier surfaces; however, at high rates a larger absolute plant number was recorded in finer soils. Two to five years after sowing, climatic conditions became more important. Full vegetation cover was achieved in all experiments. However, at high altitudes, individual plant cover became greater (and plant density decreased), probably because the grasses needed to accumulate more non-structural carbohydrates necessary to survive during the longer winter. Fertilisation accelerated the establishment of full vegetation cover by 1 to 3 years as it increased the mean cover per plant without affecting plant density. Grassland restoration is possible in mountain raw soils by using the seeds collected from nearby donor sites. High sowing densities are not required even in coarse or higher altitude soils because, in the short term, stones on the ground surface increase the percentage of seed producing established plants and, over the long term, plant density is not dependent on the sowing density. In low-fertile soils, fertilisation accelerates the establishment of full vegetation cover.
半自然草地对欧洲生物多样性具有重要意义。在山区，这些草地的恢复常常面临原生土壤稳定和恶劣气候条件等特殊问题。为了解决这些问题，人们通常会采用增加播种密度和施肥的方法。然而，过去的研究仅在一个或少数几个地点进行，且时间较短，因此无法明确展示地点特征和时间如何影响恢复效果。本研究在意大利阿尔卑斯山的 6 个原生土壤野外试验中，分析了播种密度、施肥、土壤和气候条件随时间推移对植物密度和盖度发展的影响，研究时间跨度为 3 至 6 年。种子取自附近草地，播种密度为 335-21,410 粒/平方米。在最初的 1-2 年内，低播种密度下，在多石表面的种子发芽率更高；然而，在高播种密度下，细质土壤中记录到的绝对植物数量更大。播种后 2-5 年内，气候条件变得更加重要。所有试验均实现了完全植被覆盖。然而，在高海拔地区，单个植物的盖度更大（植物密度降低），这可能是因为草类需要积累更多的非结构性碳水化合物，以在较长的冬季存活。施肥通过增加每个植物的平均盖度而不影响植物密度，将完全植被覆盖的建立时间提前了 1-3 年。即使在粗质或高海拔土壤中，也不需要很高的播种密度，因为短期内地面上的石头会增加产生已建立植物的种子百分比，而从长期来看，植物密度并不取决于播种密度。在低肥力土壤中，施肥可以加速完全植被覆盖的建立。
