Current issue: 58(4)
In an earlier paper of the author it was established that sporal regeneration of bracken fern (Pteridium aquilinum (L.) Kuhn.) is almost entirely connected with fire, and that the size of the bracken fern clones, distinguished by their characteristics, was related to the time of the fire. In previous studies has been found that also sporal regeneration of ground pine (Lycopodium complanatum L., now Diphasiastrum complanatum) is rare. The occurrence of several plant species were studied in relation to bracken fern in the earlier investigation. This paper reports findings concerning ground pine.
When the size-age problem of bracken fern was solved, parallel measurements of ground pine stand on the same site led to the solution of the size-age problem and sporal regeneration of ground pine. The linkage is also valid when the size of ground pine stands was compared to the dates of fires. The ground pine stands are very long-lasting. The stands are fragmented more easily than bracken fern by environmental factors, such as fires, and tend to form large patch clusters with time. Large individual stands reveal the rarity of sporal regeneration of ground pine. The resemblance with bracken fern clones indicate a common factor of regeneration, fire, and a very even spreading rate. Though considerable variation of the colour and structure of ground pine was observed, the circular stands were identical patch by patch.
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The present study is a part of larger project into the size and age of certain forest plants. This study seeks to confirm the size-age relationship of Lycopodium clavatum L. and L. annotium L. stands, and the time of sporal regeneration. The stand dimensions were plotted against the size of bracken (Pteridium aquilinum (L.) Kuhn) and ground pine (Lycopodium complanatum L.) stands growing on the same site, and against the age of the timber and the time of fire on the site.
The method based on parallel measurements carried out in burned forests has proved to be suitable for establishing the rate of spreading of stands and their age. The three club-moss species proved to be much alike in their sporal regeneration. They, as well as bracken, regenerate under the condition created by fire. The largest detached patches are often clones. Both Lycopodium clavatum and L. annotium survive fire poorly. Thus, the maximum size of the clones is usually connected with the last forest fire. Pieces of the shoots may survive the fires.
Sporal regeneration of these species also occur without the aid of fire. As also variation in the annual growth of the shoots can be considerable, the stand size of these species is not as good indicator of the date of fire as with Pteridium aquilinum and L. complanatum. The winding appearance of the shoots increases the error in determination of stand age by the stand size further.
The results emphasize the importance of taking into account the time and spread of the plants in the traditional vegetation analysis. A central question is: what is an individual.
The PDF includes a summary in English.