# Current Problems of Forest Protection (25-27 October 2022, Katowice Poland)
## 1 Introduction
###### Abstract  
Infestations of hemiparasitic, xylem-typing pine mistletoe are of great interest because they are rapidly spreading throughout Europe. Droughts, generally considered a major cause of tree mortality, are exacerbated by the additional effects of mistletoe on tree hydraulics and nutrition. Previous studies have not addressed declines in wood production at the stand level. In addition, there is little agreement on the effects of mistletoe on hydraulics and carbon budgets in the central portion of Scots pine's range. This work is intended to contribute to our knowledge of host plant growth, carbon dynamics and water relations in response to mistletoe infestation. We determined growth dynamics, concentrations of non-structural carbohydrates and carbon isotope ratios (613C) in wood of Scots pine (_Pinus sylvestris_) tree rings as a measure of intrinsic water use efficiency (iWUE). Material was collected from a mature pine stand in central-western Poland at a mesic site: a pine-dominated boreal forest (EFT). Ten healthy and ten infested trees were randomly selected to represent the full range of breast height diameter. Cross sections were cut at equal 2.6 m intervals along the marketable stem for detailed growth analyses. Log cores were taken at breast height and cut to obtain five-year-old annual wood samples for chemical analyses. A significant difference in growth was observed between mistletoe-infested and healthy trees with an increasing trend over time. Growth simulations indicated that over the last five years, ten years after mistletoe colonisation, the loss of usable wood yield at the stand level was \(\sim\)0.85 m\({}^{3}\) ha\({}^{-1}\) year\({}^{-1}\). Significantly higher starch concentrations (0.63 \(\pm\)0.05 SE mg g\({}^{-1}\)) were found in the outermost five rings of infested trees compared to healthy trees (0.44 \(\pm\)0.04 mg g\({}^{-1}\)). There was a significant increase in iWUE value during the last fifteen years. It increased from 91.5 \(\pm\) 1.7 SE in 2006-2010 to 94.4 \(\pm\) 1.6 (2011-2015) and 100.9 \(\pm\) 1.9 \(\mu\)mol mol\({}^{-1}\) (2016-2020). This indicates a general water limitation for pines in the studied region. We did not detect any significant difference in iWUE between healthy and infested trees. We determined that growth slowdown is a stress indicator of mistletoe infestation. Interestingly, our results suggest that this mistletoe-induced growth reduction can cause a significant loss of wood production, despite the absence of carbon and water limitations. Further research is needed to elucidate the mechanisms leading to tree growth reduction. forest yield; intrinsic water use efficiency; non-structural carbohydrates; Scots pine  
**Nature Inventory in the Forests of Regional Directorate of State Forests in Krosno (South-Eastern Poland)--Selected Entomological Aspects**  
Wojciech Grodzki, Marcin Jachym, Mieczyslaw Kosibowicz and Magdalena Ranocha  
Forest Research Institute, Krakow, Poland  
*Correspondence: w.grodzki@ibles.waw.pl  
In the period 2016-2022, in the forests of twenty-six Forest Districts (FD) within the Regional Directorate of State Forests in Krosno (south-eastern Poland), as well as in three adjacent national parks (NP): Bieszczak(BPN), Magurski (MPN) and Roztoczanski (RPN), an inventory of selected nature elements was performed in order to assess the biodiversity level in managed and protected forest stands. For this purpose, 4680 circular inventory plots were established in regular 1 x 1 km grids. On every second plot (2353 plots), an inventory of selected groups of insects was conducted. Ground beetles were captured using pitfall traps, saproxylic insects: _Cucujus cinnaberinus_ Scopoli and _C. haematodes_ (Erichson), were recorded by the inspection of standing and lying dead trees. We presented selected general results concerning the occurrence of ground beetles belonging to seven species considered as rare, as well as information on the frequency of _Cucujus_ spp.