Forests or green areas around cities and other settlements perform environmental, recreational, health, protective and other valuable functions for humans and many communities and related ecosystems. However, non-compliance with environmental standards in the economy, urban planning and nature management in general and the excessive impact of various negative factors, such as plowing of lands and town planning, lead to the disruption and fragmentation of the vegetation in these green areas and changes in the structure of their landscapes (Kucheriaviy 2001; Williams et al. 2015; Lavrov et al. 2017; Maltseva et al. 2017; Rat et al. 2017). These damages result in the elimination of unstable species and invasion of non-forest species, break ecosystem relationships, change the forest environment, structure, productivity and sustainability, and also lead to ecological role decrease (Wang et al. 2009; Potter and Woodall 2012; Prevosto et al. 2011; Huse et al. 2016; Livesley et al. 2016; Simmons et al. 2016; Abiev et al. 2017).
Forest plantations are often degraded near cities, industrial enterprises and transport communication systems. Diagnostic of anthropogenic disturbance of forest ecosystems is currently detailed at all levels of living organization (Korshikov 1996; Monitoring and Adjustment… 2011). However, assessment and comparative analysis of causation are complicated. They are results of complex interactions of different factors (chemical, physical and biological pollution, mechanical destruction of forest ecosystems on the fluctuation background of natural factors). The search of new methods to improve the diagnosis of forest ecosystem violations is quite relevant. Among the least studied issues is the evolutionary format in forest relationships between woody plants and xylotrophic fungi. They regulate the cycle of substances and chemical elements as well as the dynamics of the structural and functional organization of phytocenoses (Isikov and Konoplya 2005; Medvedev 2006; Arefiev 2010; Blinkova and Ivanenko 2014, 2016, 2018; Lavrov et al. 2017).
The wood-destroying fungi are usually characterised by macro-taxonomic indicators of the organic world organization, anatomical, morphological and functional parameters of the structure (Storozhenko 2007) and evolutionary characteristics (Bondartseva 2004; Storozhenko 2007). So far, there are not enough data on the features of changes in the xylomycocomplex species structure, its distribution and activation under the complex impact of negative factors (different origins, regimes and action intensities on different components of the ecosystem). The vulnerability and transformation of the xylomycocomplex based on the functional category of the forest, the silvicultural and taxonomic characteristics of stands and their type and structure have been insufficiently studied. We found that these differences exist (Blinkova and Ivanenko 2014, 2016, 2018; Lavrov et al. 2017). It should be expected that the violation of the taxonomic structure of stands (species composition, canopy density, mortality structure, etc.) will lead to changes in forest environment conditions, quantitative and qualitative characteristics of substrates and habitats; and change in the species structure of fungi xylotrophs, the levels of damaged trees, the rate of their subsequent mortality (or recovery) and degradation or restoration of the forest ecosystem. Therefore, this study aimed to identify and characterise changes in the species composition of wood-destroying fungi, their destructive activity and distribution of the forest ecosystem depending on the type of forest, tree species and rate of anthropogenic impact, finding out their indicator capabilities.
The research was carried out on the example of suboak and oak forest types of protective, recreational health and nature protection forests of the green zones of the Ukrainian cities (Tab. 1). In Kyiv Polissya, forests in fresh sub-forests (type of forest according to the (Pogrebnyak 1955; Migunova 2014) C2–hoS (fresh hornbeam oak sub-oakery);
Taxonomic structure of aphylophoroid fungi found in the studied forests of green areas of Kyiv (“Lyman Oshytky” tract, Lake Ebisu), Bila Tserkva (“Tovsta” tract, “Koshyk” tract) and Uman (“Bilogrudivska Dacha” tract)
Orders | Families | Species | Tracts in which fungi were found |
---|---|---|---|
1 | 2 | 3 | 4 |
Agaricales | Physalacriaceae | “Koshyk” tract | |
Pterulaceae | “Lyman Oshytky” tract; “Koshyk” tract; “Bilogrudivska Dacha” tract | ||
Schizophyllaceae | “Lyman Oshytky” tract; “Koshyk” tract; “Bilogrudivska Dacha” tract | ||
Auriculariales | Exidiaceae | “Bilogrudivska Dacha” tract | |
“Bilogrudivska Dacha” tract | |||
Auriculariaceae | “Tovsta” tract | ||
Boletales | Paxillaceae | “Lyman Oshytky” tract | |
Corticiales | Corticiales | “Koshyk” tract; “Tovsta” tract | |
“Tovsta” tract | |||
“Lyman Oshytky” tract; “Koshyk” tract; “Bilogrudivska Dacha” tract | |||
Hymenochaetales | Hymenochaetaceae | “Koshyk” tract; “Tovsta” tract; “Bilogrudivska Dacha” tract | |
“Koshyk” tract; “Bilogrudivska Dacha” tract | |||
“Lyman Oshytky” tract; “Koshyk” tract; “Tovsta” tract; “Bilogrudivska Dacha” tract | |||
“Koshyk” tract | |||
“Tovsta” tract | |||
“Tovsta” tract | |||
“Tovsta” tract | |||
Schizoporaceae | “Koshyk” tract; “Tovsta” tract | ||
“Koshyk” tract; “Tovsta” tract | |||
“Koshyk” tract | |||
Polyporales | Fomitopsidaceae | “Lyman Oshytky” tract; “Koshyk” tract; “Tovsta” tract | |
“Lyman Oshytky” tract | |||
Meruliaceae | “Koshyk” tract | ||
“Tovsta” tract | |||
Phanerochaetaceae | “Bilogrudivska Dacha” tract | ||
“Bilogrudivska Dacha” tract | |||
“Koshyk” tract | |||
“Tovsta” tract | |||
Polyporaceae | “Bilogrudivska Dacha” tract | ||
“Bilogrudivska Dacha” tract | |||
“Bilogrudivska Dacha” tract | |||
“Koshyk” tract | |||
“Tovsta” tract | |||
“Lyman Oshytky” tract; “Tovsta” tract | |||
“Lyman Oshytky” tract; “Tovsta” tract | |||
“Tovsta” tract | |||
“Bilogrudivska Dacha” tract; “Tovsta” tract | |||
“Tovsta” tract | |||
Russulales | Peniophoraceae | “Bilogrudivska Dacha” tract | |
“Koshyk” tract | |||
“Bilogrudivska Dacha” tract; “Koshyk” tract | |||
Stereaceae | “Koshyk” tract | ||
“Koshyk” tract; “Lyman Oshytky” tract | |||
“Koshyk” tract; “Lyman Oshytky” tract | |||
Thelephorales | Thelephoraceae | “Lyman Oshytky” tract | |
Tremellales | Tremellaceae | “Bilogrudivska Dacha” tract | |
Total: 9 | 17 | 46 | – |
Notes: species are indicators of different types and degrees of anthropogenic impact on forests with different species compositions.
The recreational impact on forest ecosystems was assessed by accepted methods. The stage of recreational soil digression was assessed by the Poliakov and Plugatar (2009) method. Stages of recreational digression of the forest ecosystem environment were assessed by Voron et al. (2008) of forest management in Ukraine: stage I – grass and moss cover unchanged and corresponds to the type of forest, forest litter is not disturbed, undergrowth and understorey correspond to forest vegetation conditions and are not damaged; stage II – grass and moss cover is slightly damaged, this tier is preserved, undergrowth and understorey in satisfactory and good condition (75%–90% of trees are in good and satisfactory condition); stage III – grass and moss cover is damaged over a large area, the number of forest and forest meadow grasses decreased, there are weeds or meadow grasses that are not typical for forest vegetation conditions, the layer of the cover is still preserved, the surviving undergrowth is poorly differentiated, and there are almost no seedlings of native forest-forming species; stage IV – the grass and moss cover degrades, the phytomass and the number of weeds and meadow plants have sharply increased, litter is significantly damaged, the structure of the phytocenosis is in the form of alternation of understorey curtains and low-viable undergrowth, limited by meadows and paths; stage V – grass and moss cover, typical for forest vegetation conditions of the site, degraded, the cover and phytomass of weeds and meadow plants are much larger than those of forest plants that have survived only near tree trunks, litter is almost complete demolition, undergrowth and understorey are almost completely absent, the illumination under the tent of the stand has sharply increased, and trees have mechanical damage, dried up. In most trees, the roots are bare and protrude (Lavrov et al. 2018). Mathematical processing of the research results was carried out according to the evaluation indicators of the richness of biodiversity in communities following the recommendations (Magurran 2004). The diversity of xylotrophic fungi communities was analysed according to the Shannon diversity index, Berger–Parker dominance index and McIntosh evenness index. Mathematical and statistical data processing was performed using the software “Statistica 6.0”.
Forests or green areas of Kyiv, Bila Tserkva and Uman have signs of recreational digression: littering of the territory, a network of trails, trampling of forest litter, topsoil and living ground cover, mechanical and pyrological damage to trees and their development, suppression, natural regeneration, deterioration of stands and decrease of stocking density of forest. These negative consequences increase with the decreasing distance to the sources of threats – settlements, recreation areas and transport communications. Recreational changes have certain features depending on the silvicultural and taxonomic characteristics of stands of certain functional categories, as well as the type and degree of anthropogenic load (Tab. 2 and 3). Thus, in the forests of Kyiv Polissya within a radius of 400 m from Lake Ebisu in the most degraded (stage III of recreational transformation) and weakened stands (Is=1.70–2.71) of 14 xylotroph species,
Distribution of species and finds of xylotrophic fungi in stands of different health conditions on the eco-profile with distance from Lake Ebisu (Kyiv Polissya)
№ SP | Distance from the lake, m | Species composition of the stand | Tree species | Age, yrs | Health condition index | Distribution of xylotrophs in forest ecosystems, units | The share of xylotrophs from their number at the eco-profile, % | ||
---|---|---|---|---|---|---|---|---|---|
tree species | stand | species | finds | ||||||
1 | 100 | 5Qr3Ps2Bp | 100 | 2.71 | 2.55 | 4 | 13 | 21 | |
80 | 1.75 | 2 | 4 | 5 | |||||
80 | 1.65 | 3 | 8 | 17 | |||||
Total in the stand | 2.55 | 9 | 25 | 43 | |||||
2 | 400 | 7Qr2Ps1Bp | 105 | 1.95 | 1.75 | 6 | 15 | 25 | |
60 | 1.70 | 2 | 5 | 5 | |||||
60 | 1.90 | 8 | 9 | 22 | |||||
Total in the stand | 1.75 | 16 | 29 | 52 | |||||
3C | 800 | 7Qr2Ps1Bp | 120 | 1.70 | 1.60 | 8 | 28 | 15 | |
100 | 1.65 | 2 | 9 | 5 | |||||
80 | 1.50 | 7 | 16 | 7 | |||||
Total in the stand | 1.60 | 17 | 53 | 27 |
Notes: SP – sample plot, C – control.
Characteristics of mechanical damage to tree trunks in the tract “Belogrudivska Dacha” in the green zone of Uman
№ SP-S; W, m2; N, pieces | Taxation of the first tier of the stand | Damaged trees | The area of wounds on tree trunks, S, m2 | The height of the wounds on the trunks, h, m | |
---|---|---|---|---|---|
Nd, pieces | Q, % | M ± m |
M ± m |
||
Forest areas of intensive and medium load around the sports ground | |||||
SP1-1, W = 450, N = 84 | 7Qr2Tc1Ap + Pas.Rp; CD – 0.87 | 13 | 15.5 | ||
SP1-2, W = 450, N = 67 | 7Qr2Tc1Ap; CD – 0.87 | 9 | 13.4 | ||
Areas of forest of medium and moderate load on picnic meadows | |||||
SP2-2, W = 900, N = 71 | 10Qr; CD – 0.81 | 7 | 9.9 | ||
SP2-3, W = 900, N = 69 | 10Qr; CD – 0.81 | 4 | 5.8 |
Notes: SP – sample plot; S – sections in the SP, depending on the impact of recreation: intensive – S1, medium – S2, moderate – S3 (control); characteristics of the stand: W – area of the section of the test area (m2), N – the number of surveyed trees per S, CD – canopy density; characteristics of mechanical wounds on trees of sections of SP: Nd – number of damaged trees, Q – the share of damaged individuals from all trees (%), STP – total area of SP (m2/ha), S1ha – total area per 1 ha (m2/ha); height of wounds on tree trunks h (m): M ± m – average, max – maximum, min – minimum, in section S3, mechanical wounds were found on only 1% of trees; Qr –
Xylotrophs were found on
Changes in the diversity of xylotrophs in the
№ SP | Distance, m | Shannon’s diversity index | Berger–Parker dominance index | McIntosh evenness index |
---|---|---|---|---|
1 | 100 | 1.80 ± 0.09 | 0.44 ± 0.02 | 0.71 ± 0.04 |
2 | 400 | 2.83 ± 0.4 | 0.51 ± 0.02 | 0.75 ± 0.04 |
3C | 800 | 2.89 ± 0.14 | 0.68 ± 0.03 | 0.69 ± 0.03 |
Notes: SP – sample plot, C–control.
The generalised analysis of the state stand in all areas of the massive forest of the “Bilogrudivska Dacha” tract showed that depending on the degree of recreational forest digression, the average (r = 0.97) and total area (r = 0.98) of mechanical trunk wounds increased, as well as the share of damaged trees. It is in these areas that the trampling of forest litter and the topsoil was the greatest, which depended on the distance to the sources of environmental threats (edges, roads, places of recreation or sports). There was a negative correlation between the height of the wounds (r = -0.75) and the area of traces of fires (r = -0.64) and the distance to the sports ground in the forests. The share of damaged trees, as well as the average (r = 0.97) and total (r = 0.98) area of trunk wounds, increased depending on the degree of recreational forest digression. On attractive sports grounds, picnic lawns and edges, the most vulnerable living ground cover was more trampled than forest litter.
In this tract, the distribution and taxonomic structure of wood-destroying fungi change depending on forest and taxonomic characteristics of stands and the distribution of anthropogenic disturbances. Most fungi are found on
Changes in the diversity of xylotrophs in
№ SP/S | State index of stand | Shannon’s diversity index | Berger–Parker dominance index | McIntosh evenness index |
---|---|---|---|---|
1/1 | 2.63 | 1.34 ± 0.06 | 0.40 ± 0.02 | 0.54 ± 0.02 |
1/2 | 2.32 | 1.60 ± 0.08 | 0.28 ± 0.01 | 0.48 ± 0.02 |
1/3 | 2.28 | 2.60 ± 0.13 | 0.36 ± 0.02 | 0.69 ± 0.03 |
*
Notes: SP – sample plot; S – sections in the SP.
In total, 20 species (54 finds) of xylotrophic fungi from 14 genera, 8 families, 4 orders of the Agaricomycetes class of the Basidiomycota division on 10 species of deciduous trees were found in the “Tovsta” tract. Let’s analyse the structure of the xylomycocomplex on the example of the two closest to the settlements, the most transformed stands
Distribution of xylotrophs by micro-horizons in the stands of the tract “Tovsta” of the green zone of Bila Tserkva
Fungi species/tree family | Mycohorizon | Substrate, diameter (d), cm | № SP |
---|---|---|---|
stem | trunks of living trees, d = 44 – 50 | 3, 5 | |
stem | trunks of living trees, d = 13 – 44 | 3, 5 | |
stem | trunks d = 31 – 36 | 5 | |
butt | stumps d = 9 – 20 | 3 | |
butt | trunks d = 40 – 49 | 3, 5 | |
above ground, crown | trunks of living trees, d = 10 – 56, dry branches, d = 5 – 6 | 3, 5 | |
stem | trunks d = 38 – 69 | 3, 5 | |
stem, crown | trunks and branches 1st order, d = 10 – 14 | 3, 5 | |
above ground | dry branches d = 3 | 3 | |
above ground, crown | trunks and branches, d = 25 – 40, dry branches, d = 1 – 2 | 3 |
Note: SP – sample plot.
In the suburban stand SP3, 37.5% of xylotrophic finds on
In the plantation SP5, where there is a landfill, on one find of
Analysis of the trophic structure of xylotrophs showed that saprotrophs dominated – 66% and 50.1% on TP3 and TP5, respectively (Fig. 1). The share of optional saprotrophs is approximately the same. The contribution of parasites is significant (27.7%) only on TP5, which indicates a greater transformation in this area of ecological conditions of the forest environment. Among the optional parasites,
Xylotrophs are mainly common in weakened
In the “Golenderna” tract of the “Olexandria” Arboretum of the National Academy of Sciences of Ukraine, the forest ecosystem degrades more intensively in the park; there is a decrease of canopy density, without undergrowth and understorey suburban strip of the massif 100–120 m wide (ruderalization and clogging of the phytocenosis; stage II of soil digression). Violations of the phytocenosis and ecological conditions of the forest environment according to the composition of xylotrophic fungi in the tract were revealed on the example of mycocenocells of the transition zone from park to forest type of landscape. As a result, 60 finds, 10 species, were identified:
As selective sanitary felling of trees is carried out in the tract in time, there is no dryness and trees that have fallen from the wind, respectively, there is no such category of substrates. The development of carpophores
Suppression of forest environment conditions and mycocenocellular activity is due not only to natural but also anthropogenic factors. Thus, against the background of the dominance of saprotrophs, the contribution (prevalence) of parasites in the area is 16.7% (Fig. 2). Among the optional parasites, the dominance of
Xylotrophs, especially saprotrophs, are mainly distributed (90.0%) on the drying branches of the lower shaded part of the
Xylotrophic fungi in this tract are mainly distributed in the crown horizon (75% of species and 84% of findings). Most often on
In general, the taxonomic structure of the green zones of Kyiv, Bila Tserkva and Uman we found in the studied forest tracts is given in Table 6.
Synthesising the obtained research results, as well as the data of A.G. Medvedev (2006), we offer the following list of aphylophoroid xylotrophs, which should be used as indicators of anthropogenic transformation of forest ecosystems (* – species we identified):
Severe damage to deciduous stands:
Average damage to deciduous stands:
Low damage to deciduous stands:
Severe damage to coniferous stands:
Average damage to coniferous stands:
Abiotic ecological factors are known to significantly affect the species, taxonomic, trophic, spatial and ecological structure of xylotrophic fungi (Blinkova and Ivanenko 2014; Lavrov et al. 2017). This heterotrophic evolutionary mechanism quantitatively and qualitatively combines various processes such as tree weakening, destruction of stands, accumulation of wood waste and the rate of its decomposition by fungi into a holistic balanced process that reflects the relevant structural and dynamic characteristics of the forest ecosystem (Arefjev 2010; Blinkova and Ivanenko 2014, 2016, 2018). The analysis showed that in the last three decades, researchers were most interested in anatomical, morphological and functional indicators of the structure of the forest mycocomplex in the context of evolutionary development of forest ecosystems (Bondartseva 2004; Storozhenko 2007), as well as the co-evolution of wood-destroying fungi and forest ecosystems (Bondartseva 2004; Safonov 2003). Currently, the mycobiotic phytopathology of the forest is well developed in Ukraine (Goychuk et al. 2004). However, the issues of co-adaptation of woody plants and xylotrophic fungi are less covered (Blinkova and Ivanenko 2014), even less so are the aspects of xylomycoindication of anthropogenic disturbance of forests of different purposes (Holec 2008; Lavrov et al. 2017). In other countries, researchers usually focus on the taxonomy and floristics of xylotrophic fungi (Arefjev 2010; Safonov 2003), their diversity (Bernicchia et al. 2010; Kuffer et al. 2008a), species, trophic and formation structure of mycobiota (Bondartseva 2004; Safonov 2003), its physiological impact on trees (Boddy and Watkinson 1995; Schmidt 2006), and features of their development and distribution in different regions of the world depending on the characteristics of forests and their management (Jülich and Stalpers 1980; Kotiranta and Niemela 1996; Yurchenko 2010).
Mycoindication of disturbance of forest ecosystems is currently developed in the following directions: taking into account the sensitivity of xylotrophic fungi to changes in the environment (Blinkova and Ivanenko 2014, 2016, 2018; Holec 2008; Küffer et al. 2008a, 2008b; Lavrov et al. 2017); the use of the species composition of xylotrophs to assess the anthropogenic impact on forest ecosystems (Arefiev 2010; Medvedev 2006); and the use of the system of co-adaptation of xylotrophs with woody plants in the assessment of anthropogenic impact on forest ecosystems (Blinkova and Ivanenko 2014, 2016; Holec 2008; Kotiranta and Niemela 1996). In the context of co-adaptation of woody plants and wood-destroying fungi, special emphasis should be placed on aspects of the formation and development of their consortium relationships. On the one hand, forests are key plant communities for preserving the diversity of xylotrophs – active organisms-destroyers of plant organic matter, and destroyers of lignin and cellulose (Baldrian and Lindahl 2011; Boddy and Watkinson 1995). On the other hand, xylotrophic basidiomycetes, in particular parasitic agaricoid and aphylophoroid fungi, are the causative agents of root and stem rot, as they can worsen the health condition of stands (Mukhin and Voronin 2007). However, there are certain complications and/or limitations regarding the use of xylomycocenoses for the diagnosis of anthropogenic forest disturbances that need to be considered. Yes, not all types of xylotrophs depend on a particular tree species. Eurythrophs of the first order develop on both deciduous and coniferous species. Eurythrophs of the second order develop either on deciduous species or on conifers. Only stenotrophs develop on a certain type of tree. Not all types of xylotrophs significantly depend on the development and health condition of the tree. It should be expected that the development and spread of aphilophoroid fungi may be limited by significant changes in the forest environment and substrate stock with intensive ecosystem degradation.
In general, the results of our analysis show that the most difficult questions about the use of mycoindication in assessing the state of forests arise in the context of the combined influence of negative factors – difference in origin, distribution in time and space, modes of action and the impact on various ecosystem components. The clarification of these issues requires further research at the synecological level of analysis.
The working hypothesis on the prospects of using the species structure of xylotrophic fungi to improve the methods of assessing the nature and degree of anthropogenic transformation of the forest ecosystem, especially the health condition of stands, was confirmed. Depending on the features and degree of anthropogenic transformation of forest biotopes, the ability of 37 species of xylotrophs to be indicators of deciduous and coniferous forest disturbances is substantiated. Therefore, for mycodiagnostics, it is proposed using the most sensitive to changes in the forest environment and the health condition of the tree species of aphilophoroid fungi.
Xylomycocenosis is more resistant to recreational stress in contrast to the more vulnerable structural and functional components of the forest ecosystem – grass tier, undergrowth, understorey and soil surface. Therefore, close relations between the spread and development of aphilophoroid fungi and the degree of damage and drying of trees and the intensity of recreational activity could not be found. It is also not possible to detect these relations on short eco-profiles (up to 60 m). It is likely that the recreational impact is significantly neutralised due to the complex structure and large buffer capacity of the forest ecosystem, a significant number of mechanisms for its resilience, the ability to quickly regenerate degraded elements and relations of the forest.
Xylomycocenosis is less responsive to anthropogenic load than the above more vulnerable components of the forest ecosystem: grass and ground cover, and tree stand. Therefore, in the conditions of complex negative factors that impact the forests of different nature, targeting and spatial distribution, it is advisable to use mycoindication together with assessment of grassland digression, forest litter and soil, and stand transformation.