Pažeminių gaisrų įtaka pušynų fitocenozės komponentams / | Impact of surface fires on vegetation components of pine forests.

Impact of surface fires of the middle intensity on components (moss, herb and undershrub, shrub layers, undergrowth and seedlings) of pine forest communities were analyzed in this paper. Investigations were done in pure pine forests of fifth age class, situated in Valkininkai forest enterprise. The forest fire places of 1992–2002 years were selected. Plots were placed in the fire places and nearby untouched forest as control plots. All forest community components were described. The Mann-Whitney nonparametric test was used to identify impact of fire on forest vegetation. It was determined that species richness of herb and undershrub layer was higher after surface fire. Projection cover mostly decreased first years after fire. After this disturbance abundance of Vaccinium vitis-idaea L. and V. myrtillus L. decreased. Abundance of Agrostis capillaris L., Calamagrostis epigejos (L.) Roth, Chamerion angustifolium (L.) Holub, Festuca ovina L., Melampyrum pratense L. and Solidago virgaurea L. increased. Calluna vulgaris L. disappeared in the fire places of first four years, but it recovered and its abundance increased in five year and older fire places. Species composition in moss and lichen layer has changed after fire. The lichens and mosses common in the pine forests (Dicranum polysetum Sw., Dicranum scoparium Hedw., Hylocomium splendens (Hedw.) Schimp., Pleurozium schreberi (Brit.) Mitt. disappeared. Polytrichum piliferum Hedw. and Polytrichum juniperinum Hedw. displaced them in the older fire places. Amount of undergrowth decreased first four years after fire. Saplings of Picea abies (L.) H. Karst., disappeared at all, Betula pendula Roth appeared sixth year after fire. Species number in the shrub layer decreased, Juniperus communis L. was killed by fire. Fire stimulated regeneration of Pinus sylvestris L., especially first four years after fire. Fire also improved regeneration of Betula pendula Roth and Populus tremula L.