The aim of the study was to determine the influence various feed rations had on the growth, feed conversion, and variation in body weight of European perch, Perca fluvatilis (L.), reared in a recirculating system. The three feed rations applied were: 0.5% (group F 0.5), 0.8% (group F 0.8), and 1.1% (group F 1.1) of the fish biomass. The fish in each group were marked individually and assigned to size classes: small (class S - 58.7 g), medium (class M - 77.3 g), and large (class L - 106.6 g). The stock in each tank with a volume of 1m3 was 21 individuals (three replicates for each group). The experiment was 56 days long. The highest mean body weight after eight weeks of rearing was determined in group F 1.1. The final body weight of this group was 7.5% higher than in group F 0.8 and 21.5% higher than in group F 0.5 (P < 0.05). The daily growth rate (DGR) of the fish fed the largest feed ration (group F 1.1) was 2.5 times higher than in the group fed the smallest feed ration (group F 0.5). The specific growth rate (SGR) ranged from 0.26% day-1 (group F 0.5) to 0.70% in group F 1.1, and the differences among the groups were statistically significant. The experimental results showed that the best perch rearing results were obtained using daily feed rations of 1.1% of fish biomass. Under such conditions, perch obtained larger relative and absolute daily specific growth rates.
The experiment conducted in the Kampinos National Park since 2015 was aimed at assessing the sprouting ability of black cherry (Prunus serotina Ehrh.) in response to different measures of mechanical control and mycobiota colonizing the dying trees. Basal cut-stump, cutting at ca. 1 m above the ground and girdling were performed on 4 terms, two plots and applied to 25 trees, 600 trees in total. Sprouts were removed every 8 weeks since the initial treatment for 4 consecutive growing seasons, except winter-treated trees. At the end of the fourth season of control, 515 out of 600 trees were dead (86%): 81% on Lipków and 90% on Sieraków plot. Among 18 experiment variants with sprouts removal, 17 showed more than 80% of dead trees. The lowest, 76% share, concerned summer cut-stump at the base of the tree. For winter measures, the share of dead trees was lower in all cases and ranged from 28% to 64% proving that sprouts removal contributes to the drop of sprouting strength and quicker dying of the trees. Almost 80% of trees showed sporocarps that represented 51 taxa of macrofungi in total, including 6 Ascomycota and 45 Basidiomycota. The group of six most frequently encountered fungi includes: Hyphoderma setigerum, Bjerkandera adusta, Peniophora cinerea, Armillaria ostoyae, Nectria cinnabarina, Stereum hirsutum. Both plots had similar share of black cherry individuals with sporocarps of macrofungi, that is, 81% and 78% for Sieraków and Lipków respectively. The share of colonized trees and the number of reported macrofungal taxa increased significantly compared to the year following the treatment. In addition, the composition of macrofungi changed with the progressing dying of trees. These results broaden the knowledge about macroscopic fungi colonising and living on black cherry within its secondary range of distribution. Moreover, one macrofungus and two microfungi new for KNP are reported.
New records for twenty species of saproxylic tineid moths (Lepidoptera, Tineidae) from the Białowieża Forest (NE Poland) are presented. Most species were recorded on the basis of laboratory breeding of the adult moths from the sporocarps of wood-decaying fungi inhabited by the larvae. Some species were captured using barrier traps or were collected at light. One species, Dryadaula irinae (Savenkov, 1989), is recorded for the first time from Poland and three others, Nemaxera betulinella (Paykull, 1785), Nemapogon fungivorella (Benander, 1939) and Elatobia fuliginosella Lienig & Zeller, 1846, are recognized as new for the fauna of the Białowieża Forest. The current distribution in Poland of each species is briefly discussed, and some remarks on its biology are given
Pines are generally fire-resistant trees. There is a shortage of research on the behaviour of Scots pine after surface fire in older stands. The aim of the work was to describe the effect of the surface fire intensity on the mortality of pines of various diameter at breast height (DBH), including older trees. The research was conducted in Peucedano-Pinetum oligotrophic Scots-pine forest in Kampinos National Park (KPN, central Poland) on the area of two adjacent surface fire sites originated in spring 2015 in 60- to 200-year-old stands (site area: 10,92 ha). There were 45 (28 burned and 17 control) permanent plots established after the fire. The share of not burned, superficially burned and completely burnout organic horizon of the soil was determined within all of them. DBH and location of pine trees were measured within all of the plots on the area of 200 m2. For all of the trees for which full information about soil organic horizon damage was mapped, the prevailing type of disturbance in their close neighbourhoods with radii of 1 and 2 m was assessed. The mortality of trees was assessed after each vegetation period up to 2017, basing on the presence of green needles on the trees. The influence of fire intensity on the survival of trees was examined on whole permanent plot level as well as on individual tree level. Strong linear correlation was observed between Scots pine mortality and the share of plots area with damaged organic layer, especially at the end of the third vegetation period after fire. Logistic regression models constructed for individual trees suggest that bigger tree diameter (hence, thicker bark) diminished the odds of mortality only after two vegetation periods from the fire. After the third vegetation period, only the intensity of surface fire in the close neighbourhood of trees influenced (negatively) the chance on survival. The size of trees did no matter in this case. Nearly all of the trees that were located within burnout organic matter areas died. The results did not support the commonly known mechanism of enhancement of bigger Scots pine tree survival after surface fire because of thicker bark responsible for heat protection. Probably, the main cause of observed mortality was not overheating of cambium but it was rather connected to massive fine root loses. Scots pines growing on oligotrophic arid sites modify their root system to explore topsoil layers with higher proportion of shallow roots, growing even in organic litter layer. This corresponds with massive (regardless of size) pine mortality within sites characterised by complete burnout of organic matter layer and very high survival in those ones with only surfacely burned litter layer. The results can improve the assessment of surface fires consequences in managed Scots pine stands growing in oligotrophic conditions.
The study gives information on insects living on the black alder Alnus glutinosa (L.) Gaertn. in those 57 alder stands which exhibited the most severe signs of dying back. The surveys revealed the presence of 28 species of insects belonging to various different orders. The most common species were Agelastica alni, Xiphydria camelus,Xyleborinus attenuatus (Bland.) (=X. alni Nissima) and Saperda scalaris. It seems that none of the species of insects identified would be expected to cause die back of alder over a large area. However, it was confirmed that insects do participate in the process of dying back of alder stands.
The aim of the study was to determine the growth and survival of juvenile pike, Esox lucius L., reared in recirculating aquaculture systems (RAS) and then released into earthen ponds. Three different sizes of fish were used in the experimental releases of stocking material with mean body weights of 1.5 g (group S), 7.0 g (group M), and 18.5 g (group L) which were reared in a recirculating aquaculture system and fed formulated feed exclusively. Before the fish were released, they were tagged with visible implant elastomer (VIE) tags. The highest final body weight was attained by the fish in group S, the mean body weight of which was 85.5 g, which was significantly statistically higher than in the other groups (P < 0.001). No differences in survival were noted among the groups. Positive biomass increases were only exhibited in group S (37 kg ha-1), and it was highly statistically significantly greater than it was in the other groups (P < 0.001). The results of the experiment could indicate that the suitability of juvenile pike for stocking depends on its size at release. Extending the rearing period in RAS resulted in poorer stocking results in the ponds.
The experiment conducted in the Kampinos National Park since 2015 is aimed at investigating the relationship between the dynamics of black cherry sprouting response and the type and term of implementation of the mechanical elimination procedure. It also identifies macrofungi colonizing trees undergoing eradication. Three treatments, basal cut-stump, cutting (height: ca. 1 m) and girdling, were performed on 4 terms: early and late spring, summer and winter. Each variant was conducted within two plots, and applied to 25 trees, to 600 trees in total. For two consecutive vegetation seasons, sprouts were removed approximately every 8 weeks with the exception of winter-treated trees. Qualitative data were analysed, that is, the number of trees with and without sprouts at subsequent controls, and at the end of the second season, except winter-treated trees. Initially, almost 100% of the trees cut at the base and cut high responded by sprouting. The share of trees without sprouts gradually increased during the following vegetation season, from 3rd to 5th repetition of the sprouts removal, depending on the variant of experiment. Girdling contributed to a delay in sprouting. The effectiveness of procedures, expressed as share of trees without sprouts at the end of the second vegetation season, ranged widely (12%–84%), and depended statistically significantly on the date of the treatment. The effectiveness was higher for treatments done in early (average 68%) and late spring (average 74%), as compared to those done in summer (average 35%). Mycological research concerned 600 trees, including those treated in winter, without sprouts removal. Occurrence of 26 taxa of macrofungi was confirmed on 25% of trees; most of them having wood-decaying properties. Chondrostereum purpureum was most frequent, colonizing 9% of trees. Impact of plots varying soil moisture on succession and rate of fungi colonization, and on sprouting response dynamics requires further research.