Manning George C, Baer Sara G, Blair John M
Department of Plant Biology and Center for Ecology, Southern Illinois University, Carbondale, IL, 62901, USA.
Division of Biology, Kansas State University, Manhattan, KS, 66502, USA.
Environ Manage. 2017 Dec;60(6):1062-1075. doi: 10.1007/s00267-017-0942-0. Epub 2017 Sep 29.
Fire and grazing are widely used to manage grasslands for conservation purposes, but few studies have evaluated the effects of these drivers on the conservation value of plant communities measured by the floristic quality index (FQI). Further, the influence of fire and grazing on soil properties and functions are difficult for land managers and restoration practitioners to assess. The objectives of this study were to: (1) quantify the independent and interactive effects of grazing and fire frequency on floristic quality in native tallgrass prairie to provide potential benchmarks for community assessment, and (2) to explore whether floristic quality can serve as an indicator of soil structure and function for more holistic ecosystem assessments. A factorial combination of fire frequencies (1-2, 4, and 20 years return intervals) and grazing (by bison or ungrazed) treatments were sampled for plant species composition, and for several indicators of soil quality in lowland tallgrass prairie. Floristic quality, diversity, and richness were higher in grazed than ungrazed prairie over all fire frequencies (P < 0.05). Available inorganic N, microbial biomass N, total N, and soil bulk density were also higher in grazed prairie soil over all fire frequencies (P < 0.05). Microbial biomass C, total organic C, and total soil N were positively correlated with FQI (P < 0.05). This study shows that floristic quality and soil N pools are more strongly influenced by grazing than fire and that floristic quality can be an indicator of total soil C and N stocks in never cultivated lowland prairie.
为了保护目的，火烧和放牧被广泛用于管理草原，但很少有研究评估这些驱动因素对通过植物区系质量指数（FQI）衡量的植物群落保护价值的影响。此外，土地管理者和恢复从业者很难评估火烧和放牧对土壤性质和功能的影响。本研究的目的是：（1）量化放牧和火烧频率对原生高草草原植物区系质量的独立和交互影响，为群落评估提供潜在基准；（2）探讨植物区系质量是否可以作为土壤结构和功能的指标，以进行更全面的生态系统评估。对火烧频率（1 - 2年、4年和20年的回归间隔）和放牧（野牛放牧或不放牧）处理的析因组合进行采样，以获取低地高草草原的植物物种组成和几个土壤质量指标。在所有火烧频率下，放牧草原的植物区系质量、多样性和丰富度均高于不放牧草原（P < 0.05）。在所有火烧频率下，放牧草原土壤中的有效无机氮、微生物生物量氮、总氮和土壤容重也更高（P < 0.05）。微生物生物量碳、总有机碳和土壤总氮与FQI呈正相关（P < 0.05）。本研究表明，植物区系质量和土壤氮库受放牧的影响比火烧更强，并且植物区系质量可以作为从未开垦的低地草原土壤碳和氮储量的指标。
