典型草原植物养分对生长季不同放牧强度的动态响应
摘要： 为阐明典型草原生长季放牧过程中植物养分的动态变化，本研究在2017年生长季的不同放牧阶段（放牧早期、放牧中期和休牧后）对不同放牧强度影响下内蒙古典型草原主要物种克氏针茅（Stipa krylovii）、羊草（Leymus chinensis）和糙隐子草（Cleistogenes squarrosa）的碳（Carbon，C）、氮（Nitrogen，N）、磷（Phosphorus，P）浓度及N和P阶段转移率进行了测定。研究结果显示：放牧早期阶段，放牧强度对克氏针茅、羊草和糙隐子草的C，N，P浓度、C/N和C/P无显著影响；放牧中期和休牧后，随放牧强度的增加，3种植物的C浓度、C/N和C/P显著降低，N和P浓度显著提高。休牧后3种植物的N和P阶段转移率随生长季放牧强度的增加显著降低；与克氏针茅和羊草相比，糙隐子草在重度放牧具有最高的N和P阶段转移率。本研究表明典型草原植物养分特征及策略对短期放牧具有快速调整与适应能力。
关键词: 植物养分浓度, 养分转移, 养分适应策略, 放牧试验
Abstract: Grazing alters nutrient cycling of the soil-plant system in grassland ecosystems,which greatly affects the ecosystem structure and function. Plants have rapid and sensitive responses to grazing by regulating nutrient strategies. To explore the dynamic characteristic of plant nutrients to grazing intensity in growing season in typical steppe,Carbon (C),nitrogen (N),and phosphorus (P) concentrations and periodic resorption of N and P in three dominant species (Stipa krylovii,Leymus chinensis,and Cleistogenes squarrosa) under different grazing intensities (control,light grazing,moderate grazing,and heavy grazing) were measured in different grazing periods (early grazing,medium grazing,and grazing rest) of the growing season of 2017. There were three key results in this study. C,N,and P concentrations,C/N,and C/P of S. krylovii,L. chinensis,and C. squarrosa had no significant response with grazing intensity at early grazing period. Interestingly,C concentration,C/N,and C/P of these three species remarkably decreased with grazing intensity while N and P concentrations significantly increased at middle grazing period and resting period. Periodic resorption of N and P in the three species decreased with grazing intensity at resting period. Compared with S. krylovii and L. chinensis,C. squarrosa had the highest periodic resorption of N and P in the heavy grazing. Plant C/N and C/P in the three species had significantly positive correlations with their periodic resorption of N and P,respectively. Our findings indicate the characteristic and strategy of plant nutrient have rapid change and adaptation to short-term grazing.
Key words: Plant nutrient concentration, Nutrient resorption, Nutrient adaptation strategy, Grazing experiment
中图分类号:
S812
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