The invasion of drylands by leguminous mesquite ( spp.) is frequently associated with increases in the soil organic carbon (C) and nitrogen (N) pools. These increases stimulate soil microbial activity and accelerate soil C and N cycling. However, the impact of mesquite invasion on soil biogeochemistry, especially the emission of trace gases, in an ecosystem with an already established population of N-fixing plants is not well studied. To fill this knowledge gap, we quantified the soil trace gas emissions and the potential microbial activity in soils under invasive mesquite () trees (Prosopis), native acacia () trees (Acacia), and in unvegetated soil between trees (Bare soil) on the western shore of the Dead Sea. To account for contributions of spatial and weather variabilities to the emission processes we conducted measurements across two geographic sites, 45 km apart, over two years, both under naturally dry soil conditions and after soil wetting. Before wetting, soil emissions of carbon dioxide (CO) and nitric oxide (NOx) followed the order: Acacia > Prosopis ≥ Bare soil, while soil nitrous oxide (NO) emissions were low and uniform across the three habitats. The soil inorganic N concentration, microbial biomass, and water-extractable organic C were significantly higher under the . canopies compared with . and Bare soil. After wetting, soil trace gases emissions increased up to 66, 1534, and 42 times, for CO, NO, and NOx, respectively, and remained higher under the native . than under . and Bare soil (Acacia > Prosopis > Bare soil). The potential soil microbial activity, however, was similar between the soils under the tree canopies. Our results show that the establishment of invasive leguminous trees increase soil CO and gaseous N emissions relative to the Bare soils, but not relative to native leguminous trees.

中文翻译：

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牧草树入侵干旱生态系统会改变土壤碳和氮过程以及土壤微量气体排放


豆科豆科灌木对旱地的入侵通常与土壤有机碳 (C) 和氮 (N) 库的增加有关。这些增加刺激土壤微生物活动并加速土壤碳和氮循环。然而，在已经存在固氮植物种群的生态系统中，豆科灌木入侵对土壤生物地球化学的影响，特别是微量气体的排放，还没有得到很好的研究。为了填补这一知识空白，我们量化了入侵豆科灌木（Prosopis）、本地金合欢树（Acacia）下以及树间未植被土壤（裸土）下的土壤微量气体排放和潜在微生物活性。死海西岸。为了解释空间和天气变化对排放过程的影响，我们在两年多的时间里对相距 45 公里的两个地理位置进行了测量，测量的条件是自然干燥的土壤条件和土壤润湿后的情况。润湿之前，土壤二氧化碳（CO）和一氧化氮（NOx）排放量遵循以下顺序：金合欢％3E Prosopis≥裸土，而土壤一氧化二氮（NO）排放量在三个栖息地中较低且均匀。土壤无机氮浓度、微生物量和水可提取有机碳显着升高。檐篷相比。和裸土。润湿后，土壤微量气体排放量（CO、NO 和 NOx）分别增加至 66 倍、1534 倍和 42 倍，并且在自然条件下仍保持较高水平。比下。和裸土（Acacia > Prosopis > 裸土）。然而，树冠下土壤的潜在土壤微生物活性相似。 我们的结果表明，相对于裸露土壤，入侵豆科树木的建立增加了土壤二氧化碳和气态氮的排放，但相对于本地豆科树木则没有增加。