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Forest district Janov manages forests in the middle of the north-eastern Krusne hory with area about 18.000 hectares. The forests of Krusne Hory had been cut for iron-mining purposes since the 12th century and for coal-mining since 1613. Results of bad forest management that led to the absolute lack of wood showed finally in 1717 and continued for another hundred years. Regeneration of those stands by outplanting and seed began in the 18th century. First the original-area seed was used, but later, due its lack, seed from Alps and Germany was used. Spruce (Picea abies) percentage grew up. More of beech, ash and maple stayed only in town forests of Most. Hoarfrost, glaze frost, snow and wind are abiotic injurious agents with the biggest impact on flat tops of Krusne hory. Drought damages can be also find. Red rot in stands primary damaged by deer, hoarfrost and breakage belong to the biotic injurious agents. Insect damages mainly by bark beetle were found many times during the 19th century, however the first disastrous damage came in the 60th – 80th of this century. Great problems are with summer and winter browsing by game. The worst part of all damages belongs to pollution which took almost 80% of all stands in the 60th and the 80th of this century. Spruce stands were the most attacked. The reasons are in pollution winds from power stations in Most and Chomutov region. New ways and technologies of forest work had to be find due to the unknown situation of damaged forest stands. The dieing stands on the most of the locations were cuted down. This was followed by the total soil preparation and reforestation by substituent tree species like Picea pungens Engelm., P. omorica (Pancic), Larix decidua Mill., Pinus sp., Pinus mugo Turra, Betula sp., Acer sp., etc. However those new substituent stands are not stabile enough for long-lasting forests. This is why they need to be reconstructed into target stands. The spruce health condition seemed to be better in last years, visual site was good and it had more like four years of needles. It seemed that the bad situation from the 70th and the 80th was over. However the long and cold winter 1995-96 brought disastrous results. Almost all the stands were damaged by strong south-east wind that came together with thick layer of glaze frost (most of all Birch and Larch sp.). Needles of Picea abies turned red and fell of. Stands of all ages were damaged and only few of them regenerated again.

Damaged spruce stands after the 1995-96 winter

	damaged area/ha	logging mass/m3	reduced area/ha
spruce stands (age 10-50 years)	1.391,50	11.527	190,89
spruce stands (age over 50 years)	417,77	8.349	40,69

Janov area is used for different scientific purposes and organisations, there are more than twenty different scientific objects.

Our demonstrating object documents:

• development of pollution damage
• reforestation by substituent tree species
• silviculture of substituent stands
• reconstruction into target stands