This article presents the factors influencing the formation and viability of woody vegetation in the forests of Penza region, located at the border of broad-leaved forests zone (north-eastern part) and forest-steppe (west-ern half and south-eastern part). According to the results of the National Ecological Rating of Regions, Penza region ranked 28th out of 85 Russian regions where environmental pollution is monitored. The total land area of forests is 999.3 thousand hectares, or 23.0% of the total land area of Penza region. Operational forests occupy 413.1 thousand hectares or 45.1% of the total area of land area of forest fund. Protective forests occupy 502,100 ha or 54,9% of total area of lands of forest reserve. Coniferous (pine, spruce), soft-leaved (birch, aspen, linden, alder, willow, poplar) and hardleaved (oak, ash, maple, elm) forest plantations grow on the territory of Penza region. The predominant and main tree species are Pínus sylvestris, Quercus robur, Betula pendula, Populus tremula, Tília cordata and Fraxinus excelsior. Every year, the region’s forests are affected by abiotic, biotic and anthropogenic factors. As a result of these processes there is a weakening of trees and their increased retreat in the plantation. Among the range of negative impacts on the condition of the region forests the first place is occu-pied by forest diseases (68,9% of the total area of all the negative factors), the second place - by weather condi-tions and soil and climatic factors (22,2%), the third - by forest fires (7,7%). In general, the condition of forests in Penza region is satisfactory. The most important task of forestry is to increase the productivity and quality of forests.

The article presents materials on the use of selenium compounds in the production of biological fertilizers, the main active component of which being artificially cultivated nodule bacteria. The objects of research in this work were various types of bacterial organisms used to prepare bacterial fertilizers: symbiotic nitrogen-fixing bacteria (rhizoagrin, rhizotorfin for galega and pea) and free-living agrobacteria (agrophil). Sodium selenate (Na2SeO4) was used as a source of selenium. The most optimal concentration of selenium ions in the liquid culture of microorganisms was 10–4 g/kg. A positive effect of selenium on the titer of finished preparations was observed: on average for the study period Rhizobiumpisum (rhizotorfin for peas) and Agrobacter 10 (agrophil) on the variant with selenium exceeded that on the control variant by 35.2 and 26.6%, respectively. The absolute titer values of the finished preparations Rhizobiumpisum (pea rhizotorfin) and Agrobacter 10 (agrophil) on non-sterile peat turned out to be higher than on sterile peat, although the trend remained. The inoculation of pea seeds with bacterial preparations increased the number of nodules in the flowering phase on the roots of pea plants by 1.8–2.1 times compared with the control. The treatment of pea seeds with rhizotorfin activated by selenium compounds during its manufacture increased the grain yield by 0.51 t/ha (17.1%) compared with the control, and by 0.30 t/ha (10.0%) when inoculated with rhizotorfin.