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Factors Affecting Seed Germination and Seedling Establishment of Fen-Meadow Species

Authors


Corresponding author: Institut für Pflanzenbau und Pflanzenzüchtung, Abteilung für Futterbau und Graslandwirtschaft, Universität Göttingen, Von-Siebold-Str. 8, 37075 Göttingen, Deutschland. Tel.: +49 551 392253; Fax: +49 551 399355; E-mail: jissels@gwdg.de

Abstract

Availability of seeds and provision of “safe sites” for seedling recruitment are essential for successful restoration of seminatural grassland communities. Inability to provide species-specific conditions for seedling recruitment appears to be a major factor limiting establishment of fen-meadow species on restoration sites. This contention was tested in the field for both germination and establishment conditions for a selection of fen-meadow species. A Cirsio-Molinietum fen meadow and an agriculturally semi-improved species-poor grass dominated rush pasture were used. Seeds of Carex ovalis, Cirsium dissectum, Molinia caerulea, Succisa pratensis, and Holcus lanatus were sown onto treatments comprising either irrigation or no irrigation, presence or absence of existing vegetation canopy, and presence or absence of soil disturbance. Germination of all except H. lanatus was higher in the fen meadow than in the rush pasture. The fen-meadow site was less susceptible to drought, provided more light to the seed environment, and showed a stronger day–night variation in relative humidity compared with the rush pasture. All the fen-meadow species responded strongly to the experimental treatments, whereas H. lanatus showed only a small response. Soil disturbance was the major factor that increased germination. Removal of the vegetation canopy improved germination only in S. pratensis. Conditions affecting survival of seedlings were different from those affecting seed germination. Seedling survival was greater on the fen-meadow site than on the rush pasture. Canopy presence was the major factor that reduced seedling survival. Few seedlings survived in the presence of the rush pasture canopy. Irrigation and soil disturbance were of minor importance for seedling survival on both sites. Safe sites for seed germination and seedling establishment of fen-meadow species existed on the fen meadow even without soil disturbance and gap creation. Safe sites for seedling recruitment were not present in the rush pasture. The need for species-specific definition of safe site characteristics at the two stages of seedling recruitment (i.e., for seed germination and for seedling survival) was demonstrated. The implications of these findings for restoration of seminatural grasslands are discussed.

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