State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Ying Yong Sheng Tai Xue Bao. 2023 Jan;34(1):75-82. doi: 10.13287/j.1001-9332.202301.007.
The reduction of soil nutrient content is one of the major reasons caused grassland degradation in China. Nutrient addition is thus considered as an effective measure for the restoration of degraded grasslands. However, over-fertilization can lead to decrease in plant diversity. To clarify the appropriate amount of nutrient addition and the underlying mechanism that promotes grassland restoration, we set up a nitrogen and phosphorus co-addition experiment in a degraded typical steppe of Inner Mongolia, and examined the responses at community, functional group and species levels to nutrient addition. The results showed that nutrient addition enhanced biomass while did not reduce species richness at the community level. The biomass showed a saturation response with the increases of nutrient addition, which approached saturation under the 12.0 g N·m, 3.8 g P·m treatment. Species richness increased significantly under the lower nutrient treatments (N <9.6 g·m, P < 3.0 g·m) compared with the control, while the two high nutrient treatments did not alter species richness. At the functional group level, biomass and abundance of perennial rhizome grasses increased significantly with the increases of nutrient addition levels. Biomass and density of annuals increased significantly under high nutrient addition levels. However, the abundance and biomass of perennial bunchgrasses and perennial forbs were rarely affected. At the species level, six target species responded differently to nutrient addition. Biomass of was significantly increased due to the increase of population density and individual biomass. Biomass of , and change little. Biomass of and were reduced due to the decreases in individual biomass and population density, respectively. As a measure of restoring degraded grassland, nutrient addition could significantly increase biomass and species diversity, decrease biomass of the degradation indicator species, and increase biomass of perennial rhizomes grasses.
土壤养分含量的减少是中国草原退化的主要原因之一。因此，养分添加被认为是退化草地恢复的有效措施。然而，过度施肥会导致植物多样性减少。为了阐明适当的养分添加量和促进草原恢复的潜在机制，我们在内蒙一个退化的典型草原上设置了氮磷协同添加实验，从群落、功能群和物种水平上研究了养分添加的响应。结果表明，养分添加增加了生物量，但没有降低群落水平的物种丰富度。生物量随着养分添加的增加呈饱和响应，在 12.0 g N·m、3.8 g P·m 处理下接近饱和。与对照相比，较低养分处理（N <9.6 g·m、P < 3.0 g·m）下的物种丰富度显著增加，而两个高养分处理没有改变物种丰富度。在功能群水平上，多年生根茎草的生物量和丰度随着养分添加水平的增加而显著增加。在高养分添加水平下，一年生植物的生物量和密度显著增加。然而，多年生丛生草和多年生杂类草的丰度和生物量很少受到影响。在物种水平上，有 6 个目标物种对养分添加有不同的反应。由于种群密度和个体生物量的增加，的生物量显著增加。 、 和 的生物量变化不大。由于个体生物量和种群密度的降低， 、 和 的生物量减少。作为恢复退化草地的措施，养分添加可以显著增加生物量和物种多样性，降低退化指示物种的生物量，增加多年生根茎草的生物量。
