Zheng Jiahua, Wang Qi, Yuan Shuai, Zhang Bin, Zhang Feng, Li Shaoyu, Qiao Jirong, Wu Yunga, Xing Jiaqing, Han Guodong, Zhang Jun, Zhao Mengli
Key Laboratory of Grassland Resources of the Ministry of Education, Key Laboratory of Forage Cultivation, Processing and High Efficient Utilization of the Ministry of Agriculture and Rural Affairs, Inner Mongolia Key Laboratory of Grassland Management and Utilization, College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, Hohhot 010011, China.
Forestry and Grassland Monitoring and Planning Institute of Inner Mongolia Autonomous Region, Hohhot 010020, China.
Sci Total Environ. 2023 Oct 27:168131. doi: 10.1016/j.scitotenv.2023.168131.
Predicting the impact of grazing on desert steppes' vegetation is crucial for sustainable management. The competitor, stress-tolerator and ruderal (CSR) theory has offer valuable insights into plant adaptive capacity and predicting changes in vegetation structure. However, whether adaptive strategy of desert steppe change with grazing intensity is not understood yet. We conducted a comprehensive assessment of the effects of 19 years of varying grazing intensities (no grazing: CK; light grazing: LG; moderate grazing: MG; heavy grazing: HG) on plant CSR strategies. Within the desert steppe ecosystem, the prevailing plant community strategy leaned towards SR (Stress-tolerant/Ruderal) under non-grazed conditions (C:S:R = 2:48:50 %). However, as grazing intensity increased, the S-score increased significantly from 48 % to 62 % while the R-score decreased from 50 % to 36 %. This trend persisted across functional groups and species, except for shrubs, due to the convergent response of traits and ecological strategies of these species under intense grazing pressure. Furthermore, our findings reveal that the shift of CSR on the community level was primarily influenced by soil nutrients and soil density, but not by evolutionary history (phylogenetic conservatism of traits). This suggests that plant traits co-evolved under prolonged environmental stress, resulting consistent variation and ecological strategies in desert grasslands. Overall, long-term grazing reinforced selective pressure, creating a simplified plant community structure with low levels of diversity and productivity, dominated by conservative resource-use strategy. This study highlights the mechanisms of plant adaptation to the prolonged grazing disturbance in desert steppes.
预测放牧对荒漠草原植被的影响对于可持续管理至关重要。竞争者、耐受者和杂草型（CSR）理论为植物适应能力及预测植被结构变化提供了有价值的见解。然而，荒漠草原的适应策略是否会随放牧强度变化尚不清楚。我们全面评估了19年不同放牧强度（不放牧：CK；轻度放牧：LG；中度放牧：MG；重度放牧：HG）对植物CSR策略的影响。在荒漠草原生态系统中，在未放牧条件下（C:S:R = 2:48:50%），占主导地位的植物群落策略倾向于SR（耐受胁迫/杂草型）。然而，随着放牧强度增加，S得分从48%显著增加到62%，而R得分从50%降至36%。除灌木外，这一趋势在各功能组和物种中均持续存在，这是由于这些物种在高强度放牧压力下性状和生态策略的趋同响应。此外，我们的研究结果表明，CSR在群落水平上的转变主要受土壤养分和土壤密度影响，而非进化历史（性状的系统发育保守性）。这表明植物性状在长期环境压力下共同进化，导致荒漠草原出现一致的变异和生态策略。总体而言，长期放牧增强了选择压力，形成了一个多样性和生产力水平低、以保守资源利用策略为主导的简化植物群落结构。本研究突出了荒漠草原植物对长期放牧干扰的适应机制。
