Belowground responses to altered precipitation regimes in two semi-arid grasslands
Belowground responses to altered precipitation regimes in two semi-arid grasslands
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DOI：
10.1016/j.soilbio.2022.108725
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发表时间：
2022-05-30
影响因子：
9.7
通讯作者：
McLaren, Jennie R.
中科院分区：
文献类型：
--
作者：
Holguin, Jennifer;Collins, Scott L.;McLaren, Jennie R.
预测的极端气候变化，如严重或长期干旱，可能会大大影响水资源有限的生态系统中的碳（C）和氮（N）循环。然而，我们对极端气候变化事件如何影响地下生态系统过程缺乏清晰和机械的理解。本研究探讨了5年的极端生长季干旱（减少66%，极端干旱处理）和两个月的季风降水延迟（延迟季风处理）对地下生产力和土壤地球化学的影响，在两个地理相邻的半干旱草原：奇瓦瓦沙漠草原为主的Bouteloua eriopoda和大平原草原为主的B。股薄肌五年后，极端干旱减少地下净初级生产力（BNPP）在奇瓦瓦沙漠草原，但不是在大平原草原。在这两个草原上，极端干旱增加了土壤pH值和土壤有效养分硝酸盐和磷酸盐。延迟季风处理降低了BNPP在这两个草原。然而，虽然有效的土壤硝酸盐减少在奇瓦瓦沙漠草原，延迟季风处理整体上对土壤生态系统的影响不大。极端干旱和季风延迟处理没有显着影响土壤微生物生物量，胞外酶的潜力，或土壤碳储量相对于环境条件。我们的研究表明，土壤微生物量和胞外酶活性在半干旱草原是耐5年的极端和长期的生长季节干旱，尽管土壤水分，地下生产力，土壤pH值和养分的可用性变化。
Predicted climate change extremes, such as severe or prolonged drought, may considerably impact carbon (C) and nitrogen (N) cycling in water-limited ecosystems. However, we lack a clear and mechanistic understanding of how extreme climate change events impact ecosystem processes belowground. This study investigates the effects of five years of reoccurring extreme growing season drought (66% reduction, extreme drought treatment) and two-month delay in monsoon precipitation (delayed monsoon treatment) on belowground productivity and biogeochemistry in two geographically adjacent semi-arid grasslands: Chihuahuan Desert grassland dominated by Bouteloua eriopoda and Great Plains grassland dominated by B. gracilis. After five years, extreme drought reduced belowground net primary productivity (BNPP) in the Chihuahuan Desert grassland but not in the Great Plains grassland. Across both grasslands, extreme drought increased soil pH and available soil nutrients nitrate and phosphate. The delayed monsoon treatment reduced BNPP in both grasslands. However, while available soil nitrate decreased in the Chihuahuan Desert grassland, the delayed monsoon treatment overall had little effect on soil ecosystem properties. Extreme drought and delayed monsoon treatments did not significantly impact soil microbial biomass, exoenzyme potentials, or soil C stocks relative to ambient conditions. Our study demonstrates that soil microbial biomass and exoenzyme activity in semi-arid grasslands are resistant to five years of extreme and prolonged growing season drought despite changes to soil moisture, belowground productivity, soil pH, and nutrient availability.