Organic phosphorus cycling may control grassland responses to nitrogen deposition: a long-term field manipulation and modelling study
Organic phosphorus cycling may control grassland responses to nitrogen deposition: a long-term field manipulation and modelling study
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有机磷循环可能控制草地对氮沉积的响应：长期田间操作和模拟研究
DOI：
10.5194/bg-18-4021-2021
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发表时间：
2021-07
期刊：
影响因子：
4.9
通讯作者：
Christopher R. Taylor;Victoria Janes‐Bassett;G. Phoenix;B. Keane;I. Hartley;J. Davies
中科院分区：
文献类型：
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作者：
Christopher R. Taylor;Victoria Janes‐Bassett;G. Phoenix;B. Keane;I. Hartley;J. Davies
摘要。限制磷(P)的生态系统广泛存在，但对这些生态系统如何响应人为氮(N)沉积及其对碳(C)、氮和磷的生物地球化学循环的相互作用的了解有限。在这里，我们研究了增加N添加对两个限制磷草地（一个酸性草地和一个石灰岩草地）的C - N - P库的影响，这些草地发生在对比土壤上。我们探索他们对长期营养操纵实验的反应。我们通过将数据与集成的C-N-P循环模型（N14CP）相结合来做到这一点。我们通过允许这些机制在建模框架中变化并将模型植物-土壤C-N-P输出与经验数据进行比较来探索p获取机制的作用。利用最能代表经验数据的有机磷和无机磷速效度组合模拟草地，量化草地对养分调控的时间响应。该模型表明，有机磷的获取是草地养分限制和对试验氮磷调控响应的关键决定因素。高有机磷速达率使酸性草地克服了N诱导的磷限制，增加了土壤生物量C输入，促进了土壤有机碳（SOC）的固存。相反，石灰岩草地有机磷可达性差，氮素供应加剧了磷限制，减少了土壤生物量输入，降低了土壤碳储量。因此，植物对有机磷的获取可能在降低磷限制和决定对养分有效性人为变化的响应中发挥重要作用。结果表明，不同有机磷取取量的草地对氮沉降的响应方式不同，当有机磷取取量受限时，土壤有机碳储量可能会下降。
Abstract. Ecosystems limited in phosphorous (P) are widespread, yet there is limited understanding of how these ecosystems may respond to anthropogenic deposition of nitrogen (N) and the interconnected effects on the biogeochemical cycling of carbon (C), N, and P. Here, we investigate the consequences of enhanced N addition for the C–N–P pools of two P-limited grasslands, one acidic and one limestone, occurring on contrasting soils, and we explore their responses to a long-term nutrient-manipulation experiment. We do this by combining data with an integrated C–N–P cycling model (N14CP). We explore the role of P-access mechanisms by allowing these to vary in the modelling framework and comparing model plant–soil C–N–P outputs to empirical data. Combinations of organic P access and inorganic P availability most closely representing empirical data were used to simulate the grasslands and quantify their temporal response to nutrient manipulation. The model suggested that access to organic P is a key determinant of grassland nutrient limitation and responses to experimental N and P manipulation. A high rate of organic P access allowed the acidic grassland to overcome N-induced P limitation, increasing biomass C input to soil and promoting soil organic carbon (SOC) sequestration in response to N addition. Conversely, poor accessibility of organic P for the limestone grassland meant N provision exacerbated P limitation and reduced biomass input to the soil, reducing soil carbon storage. Plant acquisition of organic P may therefore play an important role in reducing P limitation and determining responses to anthropogenic changes in nutrient availability. We conclude that grasslands differing in their access to organic P may respond to N deposition in contrasting ways, and where access is limited, soil organic carbon stocks could decline.