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首页> 外文期刊>Restoration ecology >Root Inputs Influence Soil Water Holding Capacity and Differentially Influence the Growth of Native versus Exotic Annual Species in an Arid Ecosystem
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Root Inputs Influence Soil Water Holding Capacity and Differentially Influence the Growth of Native versus Exotic Annual Species in an Arid Ecosystem

机译：根输入影响土壤持水量，并差异地影响干旱生态系统中本地和外来一年生物种的生长

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Invasion by exotic annual species is increasingly impacting Southern California arid lands, altering ecosystem processes and plant community composition. With climate change, the Southwestern United States is expected to experience increasingly variable rainfall. Larger rainfall events could facilitate invasion by exotic species that can capitalize on high resource conditions. Exotic annual species also have dense shallow root systems that could create positive feedbacks to further invasion by increasing soil organic matter and water holding capacity. Alternatively, fine root inputs could create negative feedbacks to exotic plant growth if they stimulate microbial nutrient immobilization. The dual influences of rainfall regime and fine root inputs on species performance were evaluated in an experiment where native and exotic species were grown individually and in combination under varying watering regimes (large infrequent or small frequent pulses, holding total rainfall constant) and root additions (with or without sterilized exotic roots). Mean soil moisture increased with larger infrequent watering events, and also with root addition. Plant growth (both native and exotic) increased with larger watering events, but declined with root addition. Exotic species growth declined more than native species growth with root additions. Mechanistically, root addition lowered inorganic nitrogen (N) availability, and microbial N immobilization increased with soil moisture content. Together these results show that increased fine root production promotes negative feedbacks to growth of exotic species via microbial N immobilization, especially under conditions of high soil moisture. Further, our results suggest that organic carbon additions are a potentially effective strategy for suppressing growth of problematic desert invaders.
机译：外来一年生物种的入侵正日益影响南加州干旱地区，改变了生态系统进程和植物群落组成。随着气候变化，美国西南部的降雨量将越来越多。较大的降雨事件可能会促进可利用高资源条件的外来物种的入侵。外来一年生物种还具有浓密的浅根系统，可通过增加土壤有机质和持水量产生积极的反馈，以进一步入侵。另外，如果细根输入刺激微生物养分的固定化，可能会对外来植物的生长产生负面反馈。在一项实验中评估了降雨制度和优良根系输入对物种性能的双重影响，在该实验中，本地和外来物种分别在不同的灌溉方式下（大不频繁或小频繁脉动，保持降雨总量恒定）和根系添加共同生长。有无灭菌的异国根）。平均土壤湿度随着不频繁的浇水事件以及根系的增加而增加。随着浇水事件的增加，植物的生长（本地的和外来的）都增加了，但根系的添加却降低了。外来物种的生长下降幅度大于原生植物的增长。从机械上讲，根系添加降低了无机氮（N）的利用率，而微生物固氮量随土壤含水量的增加而增加。这些结果共同表明，增加的细根产量会通过微生物固氮（特别是在高土壤湿度条件下）促进负反馈，从而通过微生物固氮来增加外来物种的生长。此外，我们的结果表明，添加有机碳是抑制有问题的沙漠入侵者生长的潜在有效策略。

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