Abstract：
Spatial redistribution of nutrients by atmospheric transport and deposition could theoretically act as a continental-scale mechanism which counteracts declines in soil fertility caused by nutrient lock-up in accumulating biomass in tropical forests in Central Africa. However, to what extent it affects carbon sinks in forests remains elusive. Here we use a terrestrial biosphere model to quantify the impact of changes in atmospheric nitrogen and phosphorus deposition on plant nutrition and biomass carbon sink at a typical lowland forest site in Central Africa. We find that the increase in nutrient deposition since the 1980s could have contributed to the carbon sink over the past four decades up to an extent which is similar to that from the combined effects of increasing atmospheric carbon dioxide and climate change. Furthermore, we find that the modelled carbon sink responds to changes in phosphorus deposition, but less so to nitrogen deposition. The pronounced response of ecosystem productivity to changes in nutrient deposition illustrates a potential mechanism that could control carbon sinks in Central Africa. Monitoring the quantity and quality of nutrient deposition is needed in this region, given the changes in nutrient deposition due to human land use.
摘要：
从理论上讲，大气运输和沉积对养分的空间再分布可以作为一种大陆尺度的机制，可以抵消由于养分在中部非洲热带森林中积累生物量而导致的土壤肥力下降。然而,它在多大程度上影响森林中的碳汇仍然难以捉摸。在这里，我们使用陆地生物圈模型来量化中部非洲典型低地林地的大气氮和磷沉积变化对植物营养和生物量碳汇的影响。我们发现，自20世纪80年代以来，养分沉积的增加可能导致了过去四十年的碳汇，其程度与大气二氧化碳增加和气候变化的综合影响相似。此外，我们发现模拟的碳汇响应磷沉积的变化，但对氮沉积的影响较小。生态系统生产力对养分沉积变化的显着响应说明了可以控制中非碳汇的潜在机制。该地区需要监测养分沉积的数量和质量，考虑到人类土地利用导致的养分沉积变化。
