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The assessment of black cherry seedlings root system was carried out at the Didactic-Experimental Establishment of the UWM in Olsztyn in September 2002. The seeds from which the examined seedlings were obtained had been sown into the ground on 2 October 2001. The following seeds were used for the experiment: fresh, sown into the ground immediately after obtaining them from fruit, partly dried seeds and seed sown a month later than in the preceding case as well as physiologically immature seeds and whole fresh fruit. The root systems of seedlings obtained from seeds stored for 1 year and 2 years in open and closed “Twist” type jars at room temperature and in a freezer were also assessed. The largest proportions of seedlings were obtained from seeds stored for 1 year and 2 years in a freezer. The lowest proportions of seedlings were obtained from seeds sown a month later and from whole fresh fruit. In this experiment the most favorable development of the root system was observed in case of seedlings from seeds stored for 2 years in an open jar. The time from picking to sowing of seeds was of little importance. The seedlings from partly dried seeds and later sowing were characterized by the lowest mass of the root system.
Prunus serotina Ehrh. is a rapidly expanding invasive in European temperate forests, threatening native species biodiversity. Three alternative models, ‘the passenger’, ‘the driver’, and ‘the opportunist’ were used to determine the interactions between the invasive species, the native community, and features of the habitat. To assess the relationships between soil properties and species composition of a Scots pine forest invaded by P. serotina, we randomly selected twelve research plots in each of four stands in the south-western part of Poland. We used the phytosociological relevé method and determined selected soil properties (total nitrogen, organic carbon, and pH value) in the organic and humus horizons. Based on redundancy analysis, we determined that selected soil properties explained 38% of the total variation in species composition of the Scots pine forest with P. serotina, indicating that community interactions followed the ‘passenger’ model. At the same time, we found that P. serotina invaded via the ‘driver’ model, since the decrease in soil C:N ratio correlated with black cherry presence, and showed a significant impact on the floristic diversity in the invaded phytocenoses. We conclude that soil parameters seem to facilitate the invasion of P. serotina, and comprise the consequences of this process.
Black cherry, Prunus serotina (Ehrh) is one of the invasive plant species that, for its ability to negatively affect local plant communities, may deserve particular attention and control measures. The authors present species composition of Coleoptera found on P.serotina in two habitats in SW part of Poland. It is the first record of this kind from Poland.
Competition is an evolutionary mechanism which exerts a selection pressure on living organisms. Forest trees compete for light, water and nutrients, especially at a young age. It was observed that the Quercus petraea and Padus serotina natural regenerations occupied the same site growing under the canopy of Scots pine (Pinus silvestris L.). To simulate the competition between young sessile oaks and black cherries found in forest, a controlled experiment was conducted using one-year-old seedlings of both species. There were eight treatments of different competition intensity. The treatments were established varying the number of potted seedlings and adding fresh cherry leaves to the substrate to enhance allelopathic effects. It was hypothesized that black cherry would reduce the height growth and diameter at root collar of sessile oak seedlings and this inhibitory effect would be magnified by an increasing number of cherry seedlings and/or fresh leaves. Black cherry as an invasive, fast-growing species was presumed to win the growth competition with oak. However, the differences in growth parameters would not only depend on genetic differences between the species, but also on the number of competing seedlings in pots and an allelopathic effect of cherry leaves. During the whole vegetative season, each two weeks, the growth parameters of seedlings (height, height increment and diameter at root collar) were measured. The results did not support the hypothesis that cherry had an inhibitory effect on oak growth, at least after one vegetative season. Contrary, a presence of cherry seedlings enhanced the oak height increment (F = 8.6, P <0.001) which might be due to either the strong interspecific competition for light or, less plausibly, positive allelopathic effect, or an interaction of both. Our results indicated a negative auto-allelopathic effect of cherry seedlings and/or fresh cherry leaves on height of cherry seedlings (F = 47.7, P <0.001). This invader showed a continuous and steep height increment within the whole vegetative season, whereas oak seedlings grew rapidly only in July. When compared the mean initial heights in April with those after the bud set in September, cherry was four fold and oak only two fold higher. A very intensive height increment gives black cherry an advantage over sessile oak at a young age which can disturb the spontaneous conversion of pine stands into a mixed pine-oak forest with a greater share of oak and other native deciduous tree species.
In forest research and nursery practice there is often a need to monitor the condition and responses of trees to different stressors. Chlorophyll content in leaf is a good indicator of plant health and can be measured rapidly in many repetitions using the chlorophyll meter SPAD-502Plus. This practical tool provides the values of chlorophyll content in relative units (SPAD values), therefore it should be calibrated for each species to determine chlorophyll content in physiological units. In this study, the chlorophyll meter SPAD-502Plus was calibrated to be used for total chlorophyll (Chl), chlorophyll a (Chl a), chlorophyll b (Chl b) and carotenoids (Car) contents determination in leaves of Quercus petraea and Prunus serotina seedlings growing in different light environments. In the same leaf, SPAD values were measured with the Chl meter, and then photosynthetic pigments content (PP; chlorophyll and carotenoids) was consistently assessed using a conventional extraction method. The measurements were conducted once a month from May to November in three light treatments to obtain the widest possible range of the PP content values. To estimate total Chl content in leaves using the chlorophyll meter the quadratic polynomial functions: y = 0.0374x2 + 0.5345x + 0.5137 and y = 0.024x2 + 2.1998x – 32.7866 were obtained from the relationship between the Chl meter SPAD readings and total Chl determined spectrophotometrically for P. serotina and Q. petraea, respectively. Chl was higher under shade compared with full light regime and Car were linearly correlated with Chl. PP content was positively correlated with air temperature except for Car in P. serotina leaves. It was concluded that at the same soil conditions chlorophyll content in leaves of Q. petraea and P. serotina depended on species, light regimes and temperature of growth. The chlorophyll meter can be used as a practical tool to monitor and compare photosynthetic pigments content in leaves between tree species or populations acclimated to different environments together with a control of abiotic and biotic factors affecting pigments content and leaf optical properties.
The Black Cherry (Prunus serotina Ehrh.), a North American forest tree, had been extensively planted for timber production in order to improve soil quality in pine plantations in European forests during the first half of the 20th century. Unfortunately, it failed to meet the foresters’ expectations. It has instead spread rapidly in silvicultures becoming a notorious weed species, difficult to control. Although it still has alien plant status, it seems that 150 years of its presence on the European continent might suffice for this neophyte to become adopted as a host plant by the native fauna of insect herbivores. The observations of Prunus serotina were conducted in 2009–2010 in the Rudno Forest District, Lower Silesia, Poland, on Prunus serotina plants growing as a thick understorey shrub layer in fresh mixed deciduous forest. The analyses, performed in 7–10 day intervals from April until the end of July each year, aimed at monitoring the population dynamics of Gonioctena quinquepunctata on P. serotina plants, and the dynamics of leaf perforation caused by this herbivore, in order to determine the relation between these two species. The insects were observed on 100 shoots on 10 plants on each observation date, and were recorded in situ. Based on the estimates of the leaf damage, the mean perforation index (PI) (%) was calculated on each date for each plant shoot, expressed as the mean percentage of the perforated leaf blade area. PI (%) was subsequently correlated with the beetle and larvae density on the plants. It has been demonstrated that the feeding of G. quinquepunctata on Black Cherry plants is more closely associated with the presence of its larvae, than with that of the beetles. Although the mean PI value on each observation date was never higher than 12%, the maximum perforation of individual leaf blades occasionally exceeded 50%, whereas the maximum mean PI calculated for individual shoots on each observation date reached as much as 47%. The authors suggest that feeding of G. quinquepunctata on P. serotina may represent an example of a well established trophic link between a native herbivore and a plant species still considered a neophyte.
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