The use of genetically improved plantlings to afforest the clear-cuts after fires in the Ob pine forests

¹Ishutin Ya.N., ¹Kluchnikov M.A., ¹Bushkov N.T.,

²Ilyichev Y.N., ¹Maskaev I.V., ²Tarakanov V.V.

¹Forest Agency of the Altai Krai, Barnaul altczl@ab.ru

²The West-Siberian Office of the Institute of Forest, SB RAS, Russia zapsibfilial@yandex.ru

The most productive pine forests of the Altai region (West Siberia, Russia) are located in the near-Ob area. Due to intensive exploitation and increased frequency of major fires the forests have deteriorated significantly over the last 50 years: the share of the pine forest decreased, during the revegetation of the clear-cut areas pine was substituted by aspen and birch. Special attention is needed for major concentrated clear-cuts after fire, where there is lack of seeds. Currently recovery of pine forests on such areas is done by continuous pine plantations. However, due to large deforested areas, high money-and labour costs of the work it is not always possible to fulfill the whole task.

Due to short financial support the survival rate of the seedlings during the first 3-4 years is very low, decreasing the efficiency of afforestation. Therefore we believe it worthwhile instead of expensive continuous plantations to establish plantations for seeding by relatively big 6-7 years old plantlings, grown from the improved seeds and having increased generative activity.

Analysis of the growth of clonal plantations showed that by the age of 15 years old the trees reached 7-8 m height and began to produce seeds. Some clones has seed production rate 3 and more times higher as compared to the average population rate. Hence the planted trees can produce and distribute seeds after 7-8 years.

Based on the published and our own data about the area of efficient seed distribution equal to the 2 tree heights, the density of pine plantlings should be 50 trees per hectare.

To assess the prospects of the method we studied the factors determining survival rate of pine seedlings on clear-cuts. We found out that on clear-cuts after fire in pine forest with mosses and berry shrubs, foliar tree species recover in groups, and turf formation is quite mosaic, from 0 to 100% area coverage. Mesorelief was found to play an important role. On 12-13 years old clear-cuts the turf coverage on small eleviations, slopes and interridge depressions was 29, 55 and 79% , respectively. Analysis of afforestation on the 12 years old clear-cut 100 m wide surrounded by pine stands showed that the age of the trees on the clear-cut were ranged from 1 to 12 years all, i.e. all age generations were present. Thus afforestation was quite successful, provided there were seeds. So the proposed method is concluded to be applicable for the forest with mosses and shrubs.

On the clear-cuts in pine forest with herbs predominant in the ground layer even sufficient amount of seeds did not result in pine seedlings appearing earlier than 1-2 years after the clear-cutting as the they had to compete with herbs. However, our studies showed that 7-9 years after the clear-cutting the merger of the foliar tree crowns inhibited herbal growth. This important finding can be used to improve pine cultures in a similar way to the foliar tree revegetation, thus increasing the share of mixed foliar-coniferous plantations and fire safety as compared to conventional afforestation methods.

The authors also discuss the experimental set-up to test and elucidate the proposed method, including their effect on population genetic variability.