Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Jilin Songnen Grassland Ecosystem National Observation and Research Station, Changchun 130024, China.
Ecological Environment Monitoring and Scientific Research Center, Songliao River Basin Ecology and Environment Administration, Ministry of Ecology and Environment, Changchun 130103, China.
Sci Total Environ. 2024 Jul 20;935:173391. doi: 10.1016/j.scitotenv.2024.173391. Epub 2024 May 23.
Long-term overgrazing may lead to the degradation of grasslands which are often characterized by an increase in nonpreferred species, especially toxic plants. However, the impact of these toxic nonpreferred species on the restoration processes of degraded grasslands is not well understood, particularly their interactions with soil properties and other plant functional groups. To address this knowledge gap, we conducted an in situ grazing exclusion experiment in a temperate degraded grassland of Inner Mongolia, China. The objective of this study was to investigate how toxic nonpreferred plants influence the recovery of plant diversity and productivity in degraded grasslands and whether these effects can be explained by changes in soil properties. Our findings revealed that Stellera chamaejasme, a toxic nonpreferred species widely distributed in North China, directly altered plant community composition and improved species diversity in degraded grasslands dominated by Asteraceae plants. The presence of S. chamaejasme could inhibit Asteraceae abundance and increase soil copper content in this study area, because Asteraceae plants have a high copper accumulation capacity. Within the communities with S. chamaejasme, the alleviation of soil copper limitation to plants may subsequently enhance the abundance and aboveground productivity of Poaceae and Forbs. Our study demonstrated that the strong direct and indirect interactions of toxic nonpreferred species with other ecosystem components promoted competitive release in terms of biomass accumulation and species diversity. The change of soil limiting microelements content caused by toxic species exerts an important mediation function during the recovery process of degraded grasslands. Thus, these toxic nonpreferred species can act primarily as accelerators for the restoration of community structure and ecosystem function in degraded grasslands.
长期过度放牧可能导致草原退化，其特征通常是增加非优势物种，尤其是有毒植物。然而，这些有毒非优势物种对退化草原恢复过程的影响尚未得到很好的理解，特别是它们与土壤特性和其他植物功能群的相互作用。为了弥补这一知识空白，我们在中国内蒙古的一个温带退化草原进行了现场放牧排除实验。本研究的目的是调查有毒非优势植物如何影响退化草原植物多样性和生产力的恢复，以及这些影响是否可以通过土壤特性的变化来解释。我们的研究结果表明，在中国北方广泛分布的有毒非优势物种瑞香狼毒（ Stellera chamaejasme ）直接改变了植物群落组成，并改善了以菊科植物为主的退化草原的物种多样性。在本研究区，由于菊科植物具有较高的铜积累能力，瑞香狼毒的存在可以抑制菊科植物的丰度并增加土壤铜含量。在有瑞香狼毒的群落中，土壤铜限制对植物的缓解可能随后增强禾本科和杂类草的丰度和地上生物量。本研究表明，有毒非优势物种与其他生态系统成分之间的强烈直接和间接相互作用促进了生物量积累和物种多样性方面的竞争释放。有毒物种引起的土壤限制微量元素含量的变化在退化草原的恢复过程中发挥了重要的中介功能。因此，这些有毒非优势物种可以主要作为退化草原群落结构和生态系统功能恢复的促进剂。
