Vegetation und vegetations-entwicklung auf kiesdächern

Summary

• 1. On gravel-covered roofs, 1 to 94 years old, in Göttingen (Germany) the following plant communities are distinguishable: Weed comm. = Panico-Galinsogetum Tread comm. = Lolio-Plantaginetum senecionetosum viscosi Poa-meadow rich in weeds = Poetum anceptis-compressae chenopodietosum albi Typical Poa-meadow = Poetum anceptis-compressae typicum Sedum-comm. p.p. = Sedo-Sempervivetum tectorum Moss.-comm. = Sedo-Sempervivetum ceratodontetosum purpurei.

• 2. The structure and habitat-conditions are discussed.

• 3. Vegetation, beginning with the weed-comm., develops during ab. 10 years into a Poa-meadow rich in weeds (which degenerates through erosion to Sedum-and moss-comm.), then on shaded places after ab. 30 years, on drier places after ab. 50 years into a typical Poa-meadow. A Sambucus-shrub may be found on (relat. moist) roofs more than 45 years old and overshadowed more than halfadays.

• 4. In northern Europe and the cooler parts of middle Europe comm. of hemicryptophytes (“meadows”) can grow on gravel-covered roofs, in southern Europe only therophyte-comm. do.

• 5. Gravel and carbonate contents, pH and ignition loss of 71 soil samples are examined.

• 6. An A-C_red soil profile is formed in the soil already after 10 years.

• 7. During moist years gravel-covered roofs are to be considered as water-stemming habitats, during dry years as very dry ones. In summer 1959 the soil water content on soil surface was as low as 1%.