7 research outputs found
The influence of shade on phenolic compounds in Scots pine
The influence of light reduction on the growth and phenolic compounds contents in Scots pine trees and seedlings was studied. Results of the first experiment in field conditions show that shade causes an increase of phenolic compounds and in the second experiment with seedlings under controlled shading conditions the results were opposite. It is suggested that the factor insolation should be paid more attention during the studies on the influence of pollution on the content of phenolic compounds
Influence of cutting off distal ends of Quercus robur acorns on seedling growth and their infection by the fungus Erysiphe alphitoides in different light conditions
Quercus robur seedlings are very often infested by oak powdery mildew caused by Erysiphe alphitoides.
This disease attacks primary leaves with high insolation. In our experiment seedling growth in different light
conditions was observed. Seedlings were derived from intact seeds or from seeds where the distal ends of
acorns were cut off. Acorns were sown in pots at four light conditions (2%, 8% and 30% light transmittance
and in full sunlight). For half of the seedlings we reduced the influence of powdery mildew by using a fungicide.
Height of seedlings, shoot dry mass and the degree of damage caused by Erysiphe alphitoides were measured.
The highest damages were in full light conditions and the lowest in the 30% light treatment. The influence
of acorn reduction on powdery mildew infection was not significant (p=0.0763), however, in the full
light conditions the seedlings from cut acorns were ca. 30% less damaged. The cutting of acorns also alters
the height of seedlings and shoot mass. The tallest seedlings were from cut seeds growing in the 30% light
treatment. The influence of the fungicide was lowest in the 30% light treatment where the decrease in damage
was only ca. 10%. For nursery practice we can say that oak seedling production from cut off acorns under
30% light transmittance should give the best results of seedling growth even without the fungicide application
Influence of mistletoe (Viscum album) on the quality of Scots pine (Pinus sylvestris) seeds
Mistletoe is semiparasite adversely affecting the functioning of their hosts especially at water
management level. So far, there have been no reports about the impact of mistletoe on seeds
from any host. The aim of the work was to evaluate the effect of the presence of mistletoe on the
quality of the seeds of Scots pine (Pinus sylvestris). Unopened cones from infected and uninfected
trees were collected in April 2015 in the Excluded Seed Stand in Bolewice Forest District
(52°2354.347N; 16°0501.978E). Measurements of cones and seeds were made. Some seeds were
used for pot experiment, where the seedlings were planted from May to October 2015. On the
second part of the seeds in the end of July and August germination tests were made. The size
and mass of the cones, the number and weight of seeds, and the height and weight of the
seedlings were lower for the material collected from the mistletoe trees. The differences were not
large but statistically significant (tabs. 1 and 2). The results showed that mistletoe has a negative
impact on the parameters of cones, seedlings and seeds quality
Temperature effects performance of Lymantria dispar larvae feeding on leaves of Quercus robur
Future climatic warming may modifyinsect development, sex ratio, quantitative changes in populations that could affect the frequency of outbreaks. Here we analyzed the influence of temperature on larval growth and development in the gypsy moth (Lymantria dispar L.). The larvae were reared at three constant temperatures: 15, 20 or 25°C, and fed with leaves of the English oak (Quercus robur L.). Larval mortality, duration of development (DD), relative growth rate (RGR), total mass of food eaten (TFE), and pupal mass (PM) were estimated. Larval mortality was lowest at 20°C, higher at 25°C, and highest at 15°C. DD significantly decreased with increasing temperature and depended on sex. The influence of temperature on the shortening of DD was stronger in males than in females. RGR significantly depended on temperature and was the highest at 25°C, and lowest at 15°C. At 15°C, RGR did not change markedly with time. In contrast, RGR at 20°C was characterized bya continuous decreasing trend. At 25°C, RGR was very high for 2 weeks but quickly declined afterwards. Temperature did not affect the TFE. PM was significantly correlated with temperature and sex. PM of females was higher at 20°C than at 15 and 25°C, in contrast to that of males, which was similar at 20 and 25°C, and higher than at 15°C. For larval growth and development, the most favourable was the medium temperature (20°C). The least favourable temperature for females was 25°C, for males 15°C. The results suggest that global warming may modifythe future sex ratio of gypsy moths that may affect insect development and outbreaks
Species composition of arthropods on six understory plant species growing in high and low light conditions
The quality of leaves as food for insects is affected both by plant species and the light conditions
present during growth. Little information exists concerning the impact of these factors on the diversity of
insects that live in the forest understory. We studied arthropod fauna on six understory plant species commonly occurring in Europe. Different groups of herbivorous insects were identified, as well as predatory
insects and arachnids. We analysed the influence of both plant species and light conditions during growth
(low light; high light) on the species spectrum, and the number of insect specimens present. The resulting
data were investigated in relation to the susceptibility of plant leaves to feeding by folivorous insects, as
determined in earlier studies. We compared the similarity in species diversity, based on the Sørensen’s
coefficient, and discussed the potential causes of observed differences in leaf damages. We found a total of
153 arthropod taxa on studied plants, under both light conditions. Corylus avellana and Prunus serotina, species characterized by greater leaf damage, have a wider diversity of arthropod species, and a greater number
of herbivorous insects. Generally, light conditions had a greater effect on arthropod abundance than on
species diversity. For two plant species, C. avellana and P. serotina, light conditions strongly, but reversely,
influenced the total number of insects and, thus, the extent of leaf damage. The number and abundance of
zoophagous species, and ratio to folivores (except C. avellana) are associated more with plant species than
with light condition
Mistletoe as a threat to the health state of coniferous forest
The forest area infected by mistletoe (Viscum album L.) in Europe has been increasing in recent years. The highest potential threat is posed by Viscum album subsp. austriacum, a parasite of Pinus sylvestris, and V. album subsp. abietis, a parasite of Abies alba. The paper presents a literature review related to biology, ecology and possible methods of limiting the negative impact of mistletoe on forest management. The vast majority of studies indicate that the presence of mistletoe negatively affects the growth as well as defensive and reproductive capabilities of trees. Due to the wasteful water management of the parasite, infected trees are particularly vulnerable to weakening during periods of drought. Mistletoe is a heliophilous taxon and forest breeding treatments should reduce light intensity in the forest canopy. Foresters should resign from leaving individual and group seed trees in forest stands inhabited by mistletoe after the cuts, because they may be a source
of seeds for the parasite invasion to the neighboring stands. The most effective method against mistletoe is cutting out the infected trees. However, removal of individual trees in forest stand may be difficult, because the most often they are the dominant and hence the most vulnerable trees in the forest management. Mistletoe is also noticeable when the number of infected trees is already very large and they cannot be removed without disturbing the stability of the forest stand. Therefore, there is an urgent need to develop methods for monitoring stands for early detection of threat. Remote sensing methods can be very useful. It is also necessary to develop management strategies with mistletoe infected stands