Articles containing the keyword 'lisääntyminen'

Clone stands of bracken fern (Pteridium aquilinum (L.) Kuhn.) wood small reed (Calamagrostis epigeios L.) and lily-of-the-valley (Convallaria majalis L.) are often partly split into two by the road, but often encountered also unilaterally on the roadside in the shape of a semicircle. The unilateral stands can be at times 20–30 m wide and they are sometimes solitary stands of the species. A method to define the age of the solitary stands of six plant species including bracken, wood small reed and lily-of-the-valley was developed in a series of earlier studies.

These stands can be used to define the time the road was built. Clones that are bound by the road unilaterally are younger than the road. If there are several unilateral clones and they are of different sizes, the road is older than the largest clone. When the road is skirted bilaterally only by clones divided by the road, it is younger than the smallest clone. When there are by the road side both unilaterally delimited clones and clones split by the road, the age of the road comes in the range of time determined by the age difference between the largest unilateral and smallest bilateral clone.

The PDF includes a summary in English.

• Oinonen, E-mail: eo@mm.unknown

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.

• Oinonen, E-mail: eo@mm.unknown