Verbreitung, Vergesellschaftung und genetische Populationsdifferenzierung des Berg-Steinkrautes (Alyssum montanum L.) auf Schwermetallstandorten im östlichen Harzvorland

Abstract

Gerth, A., Merten, D., Baumbach, H.: Distribution, community context, and genetic populationstructure of Alyssum montanum L. on metalliferous soils in the eastern foreland of the Harz Mountains. -Hercynia N. F. 44 (2011): 73 – 92.The distribution pattern and the community context of Alyssum montanum L. (Brassicaceae) on coppershale spoil heaps in the eastern foreland of the Harz Mountains (Saxony-Anhalt, Central Germany) wereinvestigated with regard to edaphic and climatic factors. Therefore, we installed transects on six spoilheaps with a total of 28 permanent plots. In the upper soil layer of all permanent plots the total amountof metals and pH-value were analysed.Alyssum montanum becomes rarer from the Saale river valley to the west and reaches its western borderof distribution in the east of Gerbstedt. In the investigated successional stage Scabiosa ochroleuca andEuphorbia cyparissias also follow this gradient. The vegetation relevés show a strong differentiation ofthe Armerietum halleri in the variation with A. montanum which is mainly characterised by the absenceof Minuartia verna, the character species of the class Violetea calaminariae. The regional distributiongradient of A. montanum corresponds to the gradients of precipitation and temperature, however it seemsto be not (exclusively) determined by them.In the upper soil layer of spoil heaps with occurrence of A. montanum we found high concentrations ofmetals (max. 27 906 mg/kg Pb, 7636 mg/kg Cu, 18 591 mg/kg Zn, 138 mg/kg Ni, 78 mg/kg Cd, 151 mg/kg Co, 116 mg/kg Cr). Therefore, Alyssum montanum has to be classified as a facultative metallophyte.Whether the species also (hyper)accumulates metals has to be proven.The AFLP (amplified fragment length polymorphism) analysis of the genetic population structure showsa geographical differentiation corresponding to regional groups of populations. Populations within thesegroups show only moderate genetic differentiation. This general pattern is caused by isolation by distance.Nevertheless, there are some exceptions explainable only by occasional long distance dispersalevents associated with the genesis of habitats in the post-mining landscape.The current distribution pattern of A. montanum is most likely caused by epizoochory and hemerochoryin the post-mining landscape from east to west starting in the Saale river valley from primary, nonmetalliferoushabitats. Apparently, the distance between spoil heaps is too large at the western rangemargin to allow further spread of A. montanum.