State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China.
State Key Laboratory of Earth Surface Processes and Resource Ecology, Faculty of Geographical Science, Beijing Normal University, Beijing, 100875, China.
J Environ Manage. 2024 Sep;368:122259. doi: 10.1016/j.jenvman.2024.122259. Epub 2024 Aug 24.
Drylands provide a wide range of important ecosystem functions but are sensitive to environmental changes, especially human management. Two major land use types of drylands are grasslands and croplands, which are influenced by intensive grazing activities and agricultural management, respectively. However, little is known about whether the ecosystem functioning of these two land use types is predominated affected by human management, or environmental factors (intrinsic environmental factors and factors modified by human management). This limits our understanding of the ecosystem functions under intensive human management in drylands. Here we reported a study where we collected data from 40 grassland and 30 cropland sites along an extensive aridity gradient in China's drylands to quantify the effects of human management intensity, intrinsic environmental factors (i.e., aridity), and environmental factors modified by human management (i.e., soil bulk density and plant density) on specific ecosystem functions (ecosystem multifunctionality, productivity, carbon storage, soil water, and soil nutrients). We found that the relative importance of each function differed between croplands and grasslands. Ecosystem functions varied with human management intensity, with lower productivity and plant carbon storage in grasslands under high grazing intensity than un-grazed, while multifunctionality and carbon storage increased with greater fertilization only in arid croplands. Furthermore, among environmental factors, soil bulk density had the greatest negative effects, which directly reduced multifunctionality in grasslands and indirectly reduced multifunctionality in croplands via suppressing crop density. Crop density was the major environmental factor that positively related to multifunctionality in croplands. However, these effects would be exacerbated with increasing aridity. Our study demonstrated that compared with the direct impacts of human management, environmental factors modified by human management (e.g., soil bulk density) are the major drivers of ecosystem functions, indicating that improving soil structure by alleviating human interferences (e.g., reducing livestock trampling) would be an effective way to restore ecosystem functions in drylands under global warming and drying.
旱地提供了广泛的重要生态系统功能，但对环境变化敏感，尤其是人类管理。旱地有两种主要的土地利用类型，即草地和耕地，分别受到集约放牧活动和农业管理的影响。然而，人们对于这两种土地利用类型的生态系统功能是主要受人类管理还是环境因素（内在环境因素和人类管理改变的因素）影响知之甚少。这限制了我们对旱地集约化人类管理下生态系统功能的理解。在这里，我们报告了一项研究，该研究在中国干旱地区的一个广泛干旱梯度上，从 40 个草地和 30 个耕地站点收集数据，以量化人类管理强度、内在环境因素（即干旱）和人类管理改变的环境因素（即土壤容重和植物密度）对特定生态系统功能（生态系统多功能性、生产力、碳储存、土壤水分和土壤养分）的影响。我们发现，不同土地利用类型的生态系统功能具有不同的相对重要性。生态系统功能随人类管理强度而变化，高放牧强度下的草地生产力和植物碳储存低于未放牧的草地，而多功能性和碳储存仅在干旱耕地中随着施肥量的增加而增加。此外，在环境因素中，土壤容重的负面影响最大，它直接降低了草地的多功能性，并通过抑制作物密度间接降低了耕地的多功能性。作物密度是与耕地多功能性呈正相关的主要环境因素。然而，随着干旱程度的增加，这些影响会加剧。我们的研究表明，与人类管理的直接影响相比，人类管理改变的环境因素（如土壤容重）是生态系统功能的主要驱动因素，这表明通过缓解人类干扰（如减少牲畜践踏）来改善土壤结构将是在全球变暖干燥条件下恢复干旱地区生态系统功能的有效途径。
