Einfluss verschiedener Bodenhilfsstoffe auf die Keimung und Entwicklung von Pionierpflanzen

With more dry periods and higher levels of damage and calamity expected in Central European forests due to climate change, alternative methods of ensuring forest site stability are needed. One method is the use of pioneer seeds, which are easier to obtain, cheaper to produce, and available in larger quantities compared to larger tree seedlings like those of climax tree species. In addition to areal use, this type of seed can also be planted under structural elements such as tripod trestles for protective forest restoration projects. To help growing seedlings better resist drought stress, it might be a good idea to use soil additives. In order to investigate the effects of different soil additives on pioneer seeds and their resulting seedlings, germination tests were carried out in this study. Unlike standard practices, the soil additives were not incorporated directly into the soil, but were applied to the surface of the soil with the seeds, as incorporation in the field is impractical. Over 28 days, the germination tests were irrigated and, during this time, the emergence of the seedlings was recorded. Afterwards, desiccation behavior was observed for another 28 days. Since soil additives include higher amounts of potassium (K), seedlings were harvested for nutrient analysis and then evaluated to see if these higher levels were found in the seedlings. A dimensionless scale with 1 = “vital,” 0.5 = “damaged,” and 0 = “dead” was used to evaluate the desiccation behavior or vitality of the seedlings. In addition, one of the soil additives was tested in the field under wooden tripods; the soil was also tilled and/or existing grass was removed, and the surviving seedlings were counted one year after they had been spread. Most of the germination tests carried out in the laboratory showed no positive, but often significantly negative influences on the germination rate compared to the respective control samples. However, it was found that the soil additives often help the plants better to survive periods of drought. Thus, for 70 % of the cases, it was possible to achieve at least a 10 % increase in the time from which the seedlings are “damaged.” In addition, the seedlings of the plants used mostly show higher K contents compared to the control samples. This is especially prominent among the soil additives, with the highest K contents. After one year, spreading the seeds under tripods in the field has shown that it is important for successful germination, on the one hand, to remove any existing grass and, on the other hand, to use a soil additive.