A field survey was conducted to detect signals of atmospheric nitrogen (N) in 11 dune systems along a nitrogen deposition gradient in the United Kingdom. In the mobile and semi-fixed dunes, above-ground biomass was positively related to N inputs. This increase was largely due to increased height and cover of Ammophila arenaria. In the long term, this increased biomass may lead to increased organic matter accumulation and consequently accelerated soil development. In the fixed dunes, above ground biomass also showed a positive relationship with N inputs as did soil C : N ratio while soil available N was negatively related to N inputs. Plant species richness was negatively related to N inputs. In the dune slacks, while soil and bulk vegetation parameters showed no relationship with N inputs, cover of Carex arenaria and Hypochaeris radicata increased. Site mean Ellenberg N numbers showed no relationship with N deposition either within habitats or across the whole dataset. Neither abundance-weighting nor inclusion of the Siebel numbers for bryophytes improved the relationship. The survey reveals that the relationships of soil and vegetation with atmospheric N deposition vary between sand dune habitats but, despite this variability, clear correlations with N inputs exist. While this survey cannot establish causality, on the basis of the relationships observed we suggest a critical load range of 10 - 20 kg N ha(-1) yr(-1) for coastal sand dunes in the UK.
展开▼
机译:进行了现场调查,以检测英国11个沙丘系统中沿氮沉降梯度的大气氮(N)信号。在流动和半固定的沙丘中,地上生物量与氮输入呈正相关。这种增加主要是由于沙门氏菌的高度和覆盖率增加。从长远来看,这种增加的生物量可能导致有机质积累增加,从而加速土壤发育。在固定沙丘中,地上生物量也与N输入呈正相关,土壤C:N比也是如此,而土壤有效氮与N输入负相关。植物物种丰富度与氮输入负相关。在沙丘松弛区,土壤和大量植被参数显示与氮输入无关,而沙地苔草和辐射草的覆盖率增加。站点平均Ellenberg N数与生境内或整个数据集中的N沉积均无关。苔藓植物的丰度加权或Siebel数的包含都不能改善这种关系。调查显示,沙丘生境之间土壤和植被与大气氮沉降的关系有所不同,但尽管存在这种可变性,但与氮输入之间存在明显的相关性。虽然此调查无法确定因果关系,但根据观察到的关系,我们建议英国沿海沙丘的临界载荷范围为10-20 kg N ha(-1)yr(-1)。
展开▼