It is still common practice in Europe to dike salt marshes for agricultural use. This impacts both the vegetation and physical environment of the marsh. We studied the plant community, environmental conditions, and determined correlations between vegetation cover and diversity with environmental factors on an enclosed marsh, which has been behind a dike since 1890. Vegetation data from both salt marshes without dikes and fresh meadows are routinely sampled by the Danish Environmental Protection Agency and were here used to assess whether the plant community of the shielded marsh resembled that of either salt marshes or fresh meadows. The century-long elimination of tidal and storm flooding has resulted in low salinity levels (0.4–5.13 ppt), low available P (0.36–4.90 mg/100 g soil), and high total N (0.68–28.82 g/kg). The plant community of the shielded marsh demonstrated a mean species richness (11.4) similar to that of other salt marshes but was no longer characterized by the same composition of halophytes (ANOSIM, p < 0.001). However, despite the century-long shielding the vegetation does not resemble that of the nearby fresh meadow community (ANOSIM, p < 0.001). Therefore, prohibiting tidal floodings by dikes does not protect the salt marsh habitat but instead results in a habitat that contains both halophytes and glycophytes.

在欧洲，将盐沼堤防用于农业用途仍然是很普遍的做法。这会影响沼泽的植被和物理环境。我们研究了植物群落，环境条件，并确定了自1890年以来一直围堤的封闭沼泽中植被覆盖度和多样性与环境因素之间的相关性。丹麦环境保护局（Denmark Environmental Protection Agency）并在此处用于评估被保护沼泽的植物群落是否类似于盐沼或新鲜的草地。长达一个世纪的潮汐和风暴洪水消除导致低盐度（0.4-5.13 ppt），低有效磷（0.36-4.90 mg / 100 g土壤）和高总氮（0.68-28.82 g / kg）。p <0.001）。然而，尽管长达一个世纪的屏蔽，植被与附近的新鲜草甸群落却没有相似之处（ANOSIM，p <0.001）。因此，禁止堤防潮汐洪水并不能保护盐沼栖息地，反而会导致既包含盐生植物又包含糖类植物的栖息地。