Soil fungi communities from young Scots pine plantations affected with root rot

The aim of work was to investigate the qualitative and quantitative characteristic features of soil fungi associations occurring in I class pine stands threatened by pathogens of tree roots in Zielonka Experimental Forest District (W Poland). During the mycological analyses of soil, a total of 694 isolates of fungi representing 33 species were obtained. The most numerously represented species was Penicillium daleae which made 75% of all isolates. The second place in the ranking belonged to Penicillium janczewski amounting to 11%. In order to define the qualitative and quantitative similarity between the studies areas, a proportional inconformity was determined. The greatest similarity occurred between the associations of soil fungi obtained from site 64c and 35b.


INTRODUCTION
Fungi occur in all environments; they play an important role, both a positive and negative one, in the life of other organisms and ecosystems.Soil environment is very favorable for fungi, they participate in the decomposition of dead organic matter, particularly in conditions of a low pH level which limits the activity of bacteria, and they enter into mycorhizal relations with trees.There is no doubt that there exist many factors affecting the quality of relations dominating in the soil determining thereby the occurrence of the particular species of organisms or whole organism associations.Associations of organisms occurring on a given area together with arbores cent species decide about the quality of ecological factors in the given place reacting to all changes taking place there (M a ń k a 1974).Therefore, it is important to get familiar with the biodiversity of these associations (K o w a l s k i 1996) which can decide about the health of plants (D a h m , S t r z e l c z y k 1977).The objective of the present study was to investigate the qualitative and quantitative characteristic features of soil fungi associations occurring in I class pine stands threatened by pathogens of tree roots.

MATERIALS AND METHODS
Studies were carried aut in seven separated sites (Tab. 1) localized in I class pine stands of the Experimental Forest District Zielonka (W Poland).
In each separated site, soil samples were taken from one studied area in order to isolate fungi communities.Soil for mycological analyses was taken from the depth of 5-20 cm from 6 sites uniformly distributed on a circle with an about 6 m radius.The obtained 6 samples were mixed, givining in this way a sample of about 1 dm 3 volume.Fungi were isolated using Warcup's method (Wa r c u p 1950) in the modification of K. Mańka (J e n s e n , M a ń k a 1961; M a ń k a , S a l m o n o w i c z 1987).From each flask containing soil and sand, 10 Petri dishes were prepared.In this way, the mycological soil analysis from one area was based on 30 Petri dishes.Incubation was carried out for 7 days at room temperature.After this period, the first colonies of fungi which developed on Petri dishes were separated.Fungi separation was repeated after 3 successive days.The developed fungi colonies were transferred to test-tubes with agar-glucose-potato nutrients.After 2-3 weeks of incubation, the separated isolates were described.The description included the dish number from which the colony of fungi was separated and the successive number of test-tube.Then, the developed mycelia were compared and groups with the same macroscopic features were separated.After 2 weeks, the representatives of these particular groups were transferred to Petri dishes with agar-glucose-potato nutrient.After 10 days of incubation, the fungi were identified and described.In this way, soil fungi associations obtained and systematized.In order to determine the qualitative and quantitative similarities of the soil fungi communities obtained from the studied areas, on the basis of the number of common and different species, the formula of Marczewski-Steinhaus (Ro m a n i s z y n 1972; L e ś n i a k 1984; S i e r o t a 1995; K o w a l s k i 1996; Ty s z k i e w i c z 2001) was applied.

Ta b l e 1 Characteristic and location investigation area
where: S -similarity of two mutually comparable soil fungi communities a -number of isolates of fungi communities 1, b -number of isolates of fungi communities 2, w -number of fungi association isolates common for both associations (1 and 2).
It is assumed that if the comparable communities have all features in common, the similarity is S = 1 or 100%.If the studied communities have no common features, then their similarity is S = 0. Also the so called distance between the communities was determined: the more features are common, the smaller is the distance, and the less features are common, the greater is the distance.The distance of two associations (r) is expressed by the formula: Because of the discrete character of the data, in order to define the qualitative and quantitative similarity between the studies areas, a proportional inconformity was determined.The distance between the areas has been illustrated on dendrograms using the method of mean connections (D o b o s z 2001).

RESULTS
During the mycological analyses of soil, a total of 694 isolates of fungi representing 33 species were obtained.The most numerously represented species was Penicillium daleae which made 75% of all isolates and it was present in all associations from all studied sites.The second place in the ranking belonged to Penicillium janczewski amounting to 11% and it was also present in all the studied associations except for the association from site 47k.The successive rank belonged to Chrysosporium merdarium (7%), Ch. pannorum (7%) and Penicillium stecki (4%).Species group which occurred sporadically, they were represented by one isolate only, included: Mortierella isabelina, M. microspora var.macrocystis and two non-sporiferous species.
The most numerous soil fungi association was obtained from site 85c, it consisted of 179 isolates representing 13 species.The least numerous was the community of soil fungi from site 47k including 63 isolates represented by 10 species.The poorest community regarding its qualitative aspect was the association from site 35b represented by 9 species of soil fungi.
Table 2 contains the qualitative and quantitative composition of soil fungi associations from the particular studied areas.
In order to determine the qualitative similarities of fungi associations, on seven analyzed areas, similarity cocfficients of associations were determined according to the formula of Marczewski-Steinhaus (Tab.3).Similarity determined in this way shows only the fact of occurrence or absence of the given fungi, but it does not indicate their frequency.The greatest similarity.As height as 60% occurred in case of soil fungi communities from sites 64c and 35b.The least similarities were found between the communities of soil fungi from sites 47k and 43f amounting only to 11%.Other soil fungi associations showed a similar qualitative similarity ranging between 14 and 31%.
During the studies, the coefficient of the proportional distance between the associations was determined taking into consideration also the frequency of the given fungi species in the associations.The obtained coefficient values have been illustrated in the form of a dendrogram (Fig. 1).The greatest similarity occurred between the communities of soil fungi obtained from site 64c and 35b.The communities of soil fungi obtained from site 85c was the most different from the other ones.

DISCUSSION
On the studies areas where soil samples were taken for mycological analyses, observation were carried out referring to the monitoring of infections diseases of tree roots (S z e w c z y k 2005).On all studied areas, there occurred pine infestations by A. ostoyae.An exception was site 35b where pine were attacked by H. annosum.In all studied areas there grew young planted trees, the soil was prepared in the same way (furrow ploughing) and the trees were in a similar age (9-13 years), however, they occupied different forest sites (Fresh coniferous forest, fresh mixed coniferous forest and Fresh mixed broadleaved forest).On the basis of a determined similarity of associations and the coefficient of proportional distance, one can conclude that there is no dependence between the qualitative and quantitative composition of soil fungi and the occurrence of Armillaria ostoyae and Heterobasidion annsoum, the forest sites type and the age of trees on the areas where samples were taken.All obtained isolates represented commonly occurring soil fungi.Some of them can have an effect on Armillaria spp. or Heterobasidion annosum.The most frequently occurring fungus type was Penicillium janczewski characterized by the production of enzymes which decompose cellular walls of wood making thereby an entrance for infection of Armillaria spp.(B ä ä t h , S o d e r s t r ö m 1980).Another type of fungus which may have an effect of Armillaria spp. is Trichoderma which trough antibiosis can limit the growth of rhizomorphs (S h o w , K i l e 2001).Fungi of Mortierella type do not play any significant role in soil metabolism, but they are able to decompose chitin Acremonium spp.Can be pathogens for humans and animals: the same refers also to Aspergillus spp. or Penicillium spp.causing sapergollotoxicoses and penicillotoxicoses.

Fig. 1 .
Fig. 1.Percentage distance between soil fungi community coming from compartment in Zielonka Experimental Forest District.