University of Rostock, Grassland and Fodder Sciences, Justus-von-Liebig-Weg 2, 18059 Rostock, Germany; Michigan State University, Center for Global Change and Earth Observations, 48824 East Lansing, MI, USA.
University of Rostock, Grassland and Fodder Sciences, Justus-von-Liebig-Weg 2, 18059 Rostock, Germany.
Sci Total Environ. 2021 Aug 10;781:146720. doi: 10.1016/j.scitotenv.2021.146720. Epub 2021 Mar 25.
In mountain pastures worldwide, studies investigating vegetation changes due to long-term grazing and environmental changes are sparse, especially regarding the effects of changes in snowmelt patterns. The outstanding availability of historical vegetation data from Kyrgyz mountain pastures creates unique opportunities to study past and forecast future changes, making them ideal model ecosystems. Using a resurvey approach, we explored the response of mountain vegetation to management and environmental changes in the Western Tien-Shan to investigate whether plant communities of six vegetation types (ecozones) had changed over 42 years, whether changes were related to management or ecological causes and whether species' mean elevational ranges had changed. We assembled historic vegetation data (1973-1987) in six ecozones that were resurveyed annually from 2008 to 2015 and connected them with species' management-related traits and ecological indicator values. Overall, a homogenization of vegetation within and among ecozones was observed. Mountain steppe, meadow-steppe, and subalpine meadows showed the strongest convergence towards a dominance of mesic shrubs, related to increasing precipitation changing soil moisture and soil-salt regimes. In the high mountain steppe and the alpine ecozone, cushion dwarf shrubs increased, driven by increased soil moisture following faster snowmelt. Changes in the semidesert were related to highly variable spring soil moisture. Compositional changes accelerated over time. Mostly palatable species declined in abundance. More competitive unpalatable species replaced abundant (1973) unpalatable species. Mean elevation shifted significantly for 35 species (out of 136), with 60% shifting >100 m, more often upward (low and high elevations) than downward (mid-elevations). These mountain ecosystems seem more sensitive to changing precipitation than temperature- or grazing-induced changes, making climatic change a more important driver than management. Further adaptive management should consider the response of the vegetation to environmental changes and promote alternative land-use options to maintain ecosystem functioning. In mountain ecosystems worldwide, the observed acceleration of changes might go unnoticed, calling for long-term studies and global climate-vegetation-management interaction models.
在世界各地的高山牧场上，由于长期放牧和环境变化而导致的植被变化的研究很少，特别是关于融雪模式变化的影响。吉尔吉斯高山牧场上历史悠久的植被数据的出色可用性为研究过去和预测未来的变化创造了独特的机会，使它们成为理想的模型生态系统。我们使用再调查方法，探索了天山西部高山植被对管理和环境变化的响应，以调查六种植被类型（生态区）的植物群落是否在 42 年内发生了变化，变化是否与管理或生态原因有关，以及物种的平均海拔范围是否发生了变化。我们收集了六个生态区的历史植被数据（1973-1987 年），这些数据在 2008 年至 2015 年期间每年进行重新调查，并将其与物种与管理相关的特征和生态指标值联系起来。总的来说，观察到生态区内部和之间的植被同质化。山地草原、草甸草原和亚高山草甸表现出与增加的降水改变土壤水分和土壤盐分状况有关的最强的向中生灌木优势的趋同。在高山草原和高山生态区，由于融雪速度加快导致土壤水分增加，垫状矮灌木增加。半干旱地区的变化与春季土壤水分高度可变有关。组成变化随着时间的推移而加速。大多是美味的物种数量减少。更多具有竞争力的不可口物种取代了丰富的（1973 年）不可口物种。有 35 个物种（136 个中的 35 个）的平均海拔发生了显著变化，其中 60%的物种海拔上升了>100 米，向上（低海拔和高海拔）的变化多于向下（中海拔）。与温度或放牧引起的变化相比，这些高山生态系统对降水变化似乎更为敏感，气候变化比管理更为重要。进一步的适应性管理应考虑植被对环境变化的响应，并促进替代土地利用选择，以维持生态系统功能。在世界各地的高山生态系统中，观察到的变化加速可能没有被注意到，因此需要进行长期研究和全球气候-植被-管理相互作用模型。
