Influence of humidity, lighting, microsite and germination bed on the germination and development of Douglas firs of different provenances - a greenhouse experiment
Since its establishment in Europe, the Douglas fir (Pseudotsuga menzisii Mirb. Franco) species has been of great interest, particularly for economic reasons. However, with the growing relevance of the natural regeneration potential of this tree species, silvicultural questions regarding the establishment of regeneration are increasingly coming to the fore. In this context, the quantitative and qualitative documentation of the earliest stages of development provides information on potential control options for regeneration success. Regional experience in estimating early mortality risks in alien tree species under Central European stand conditions has so far only been available in isolated cases.
This project is based on the following methodological and content-related objectives:
| - | A controlled recording of germination success can be realized with a standardized test facility, taking into account decisive environmental parameters such as radiation and humidity (relevance for other tree species). |
| - | The technical possibilities for implementing continuous or periodic moisture measurements on naturally stored (heterogeneous, non-standardizable) substrates are to be tested and further developed with regard to their applicability. |
| - | Specific recording criteria are to be developed for recording qualitative seedling development and growth, depending on the respective stage of the seedling, which also allow transferability to other tree species. |
| - | By integrating different origins of P. menziesii into the studies, the relevance of different factors and combinations of factors can also be examined for the earliest development phase and with a view to the origin recommendations of forestry practice. |
| - | The success of germination and establishment can be quantified with the help of characteristic parameters such as germination percentage, germination speed, germination progress and mortality. The characteristic environmental factors of the micro-location - humidity and radiation - are considered to be significant control variables in this development phase. In addition, statements can be made that differentiate between the importance of germination capacity (seed quality) and the effects of the microsite on establishment. |
| - | The evaluation of qualitative seedling development by means of morphological and physiologically relevant response criteria supplements the quantitative assessment. It also enables statements to be made about the vitality of Douglas fir seedlings under defined, small-scale environmental conditions and their further probability of survival. |