Our aim was to determine dynamics in a population of tawny owls Strix aluco over 15-year period, in relation to year-to-year variation in environmental conditions. The research was carried out in a habitat mosaic of fields and forest in central Poland, over the 2004−2018 period. Numbers of pairs (territories) were established by the standard playback survey technique supplemented by searches for nest sites. The selected environmental factors studied in parallel were the acorn production, density changes in field and forest rodents, meteorological conditions in winter and density of martens (Martes spp.). At the start of the study period 20 nest boxes designed for tawny owls were placed out in the study area. This number was enlarged by additional 27 nest boxes placed in 2012. The number of owls in the area remained stable-in the range of 26−29 pairs, despite changes in nesting sites availability. However, moderate influence of rodent density and winter conditions on population abundance was detected. Also, peak in the rodent population coincided with greater clutch size and numbers of young owls reared. Densities of martens remained relatively stable throughout the study period, and there were no reported cases of these carnivores killing tawny owls, despite the former taking shelter in the owl-boxes.

Meteorological measurements, that aim to monitor weather and climate conditions to aid research in changing forest ecosystems, have been conducted in the Warsaw University of Life Sciences’ experimental forests in Rogów since 1924. Based on the long-term air temperature measurements, it can be demonstrated that in the years 1924–2015, anomalously cold months have occurred less often (ca. 3.2%) than anomalously warm months (ca. 4.5%). During the last 20 years, only two anomalously cold months were recorded (November 1998, December 2010), whereas anomalously warm months occurred frequently (May 2002, July 1999, 2002, 2006, 2010, 2012, 2014, August 2002, 2015, September 1999, 2006, October 2000, 2001). We hypothesised that the more frequent anomalously warm months would constitute a trend in increasing the air temperature for particular months between 1924–2015, but surprisingly, a statistically significant trend was observed for all winter (XII–II) and spring months (III–IV) as well as the end of summer (VIII).

Air pollution and climate change are two key factors comprising the global change threat to forest health and sustainability. Intensive development of industry in the second half of the 20th century brought significant changes in the level of pollutants emitted into the atmosphere in Poland. Dry and wet deposition of toxic pollutants (mainly SO2, NOx, & NH3), continuing over more than 40 years, has caused serious damage to forest stands. One of the ways describing the effect of industrial emissions on forests is the tree-rings (dendrochronological) analysis, it has been used in our research. We present a brief description of the studies on impact of air pollution on growth of forest growing in the most polluted areas of Poland. The main aim is to evaluate of Scots pine stand degradation caused by the pollutants emitted from the one of biggest polluters of the environment in Poland for over 25 years (1966-1990). We found that pollutant emission caused disturbances of incremental dynamics and long-term strong reduction of growth. Scott pine growing in the vicinity of the nitrogen fertilizer factory showed a dramatic growth reduction after the beginning of the pollution period. Significant decrease in growth was observed for the majority of investigated trees (75%) to the end of the 1990s. The zone of destruction extends primarily in easterly and southern directions, from the pollution source, associated with the prevailing winds of the region. At the end of 1990s decreasing trend stopped and the wider tree-rings could be observed. This situation was related with a radical reduction of ammonia emissions and an improvement of environmental conditions. However, growth of damaged trees due to the weakened health condition is lower than the growth of Scots pine on the reference plot and trees are more sensitive to stressful climatic conditions, especially to drought.

The purpose of this study was to determine the growth variability of four provenances of Picea abies on experimental plots in the Wyszków Forest District, central Poland. The experiment was established as a system of random blocks with four repetitions per block. We selected 48 trees from each provenance and the increment cores were colected from sample trees. Standard measurements of the width of annual increments were performed using the WinDendro software. Raw data was then indexed and subject to dendroclimatic analyses based on the average monthly temperatures and precipitation of the period from 1969 to 2012. Furthermore, the COFECHA software was used to check the consistency of the data and to determine the pointer years. High data consistency as well as growth variability of particular provenances in response to climatic conditions was observed. The results obtained here will allow for an improved selection of populations best suited for growing in the climate of central Poland

Over the past decades, relatively few experimental studies have been carried out in which the micrometeorological conditions have been studied over different small clearings plots of the forest. As these conditions can significantly affect many processes in the ecosystem, two questions arise: 1) whether and how the microclimatic conditions differ in the clear-cut and the gap, and 2) how heterogeneous is the distribution of these conditions on these plots. The aim of the study was to determine the spatial variation of air temperature on the clear-cut and gap as well as to compare the distribution of thermal and humidity conditions on both areas. The research was carried out in Central Poland on a clear-cut with a width of 60 m and on a gap of an ellipsoid shape (40 × 70 m). The measurements were carried out in two series: spring-summer, in the period when the height of the sun during the day conditioned inflow of direct solar radiation to any surface (May-August 2006), and autumn, when direct radiation was limited by neighbouring stands (October-November 2006). Average values of air temperature on the gap in the spring-summer period differed in individual parts of 2.2 o C, while on the clear-cut by 1.0 o C. In the autumn, thermal diversity on both research plots was similar (average 0.8 o C). The thermal diversity within the research areas was particularly marked in the case of extreme air temperature values. We found the modest spatial diversification of humidity parameters: vapour pressure, relative humidity, and humidity deficit. Particularly large diversification of relativity humidity and vapour pressure deficit were claimed in spring-summer period in the situation of heat waves. The least beneficial thermal and humidity conditions for plants growing occurred in the northeast parts of clear-cut and gap, that is why it necessary to take particular note of these locations during undertaking the silviculture.