Response of Organic and Inorganic Carbon and Nitrogen to Long-Term Grazing of the Shortgrass Steppe
Response of Organic and Inorganic Carbon and Nitrogen to Long-Term Grazing of the Shortgrass Steppe
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DOI：
10.1007/s00267-003-9106-5
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发表时间：
2004-03
影响因子：
3.5
通讯作者：
J. Reeder;G. Schuman;J. Morgan;D. Lecain
中科院分区：
文献类型：
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作者：
J. Reeder;G. Schuman;J. Morgan;D. Lecain
研究了科罗拉多东北部短草草原长期（56 a）放牧对植物-土壤系统（至90 cm深度）有机碳和无机氮含量的影响。放牧处理包括连续的季节（5月至10月）放牧的一岁小母牛在重（60-75%的利用率）和轻（20-35%的利用率）的放养率，和nongrazed围栏。沉重的放养率导致的植物群落，占主导地位（75%的生物量生产）的C4草蓝色格兰玛（Bouteloua gracilis），而不包括牲畜放牧增加了生产的C3草和仙人掌（仙人掌polycantha）。土壤有机碳（SOC）和有机氮在轻度放牧和非放牧处理之间没有显著差异，而重度放牧处理的SOC比非放牧处理高7.5 Mg ha− 1。净矿化氮与总有机氮的比例较低，在这两个放牧相比，非放牧处理表明，长期放牧降低了土壤有机质的易矿化部分。重度放牧对土壤无机碳（SIC）的影响大于SOC。重度放牧处理的土壤总碳（0-90 cm）比非放牧处理高23.8 Mg ha− 1，（16.3兆亿公顷-1）归因于较高的SIC，32%（7.5毫克公顷−1）这些结果强调了在半干旱和干旱生态系统中包括无机C在评估土壤中无机C的质量和分布的重要性。植物土壤碳和放牧管理对碳固存的影响的评估。
We investigated the influence of long-term (56 years) grazing on organic and inorganic carbon (C) and nitrogen (N) contents of the plant–soil system (to 90 cm depth) in shortgrass steppe of northeastern Colorado. Grazing treatments included continuous season-long (May–October) grazing by yearling heifers at heavy (60–75% utilization) and light (20–35% utilization) stocking rates, and nongrazed exclosures. The heavy stocking rate resulted in a plant community that was dominated (75% of biomass production) by the C4grass blue grama (Bouteloua gracilis), whereas excluding livestock grazing increased the production of C3grasses and prickly pear cactus (Opuntia polycantha). Soil organic C (SOC) and organic N were not significantly different between the light grazing and nongrazed treatments, whereas the heavy grazing treatment was 7.5 Mg ha−1higher in SOC than the nongrazed treatment. Lower ratios of net mineralized N to total organic N in both grazed compared to nongrazed treatments suggest that long-term grazing decreased the readily mineralizable fraction of soil organic matter. Heavy grazing affected soil inorganic C (SIC) more than the SOC. The heavy grazing treatment was 23.8 Mg ha−1higher in total soil C (0–90 cm) than the nongrazed treatment, with 68% (16.3 Mg ha−1) attributable to higher SIC, and 32% (7.5 Mg ha−1) to higher SOC. These results emphasize the importance in semiarid and arid ecosystems of including inorganic C in assessments of the mass and distribution of plant–soil C and in evaluations of the impacts of grazing management on C sequestration.