The proposal of a new provisional border of range of the acidophilous oak forest Calamagrostio arundinaceae-Quercetum petraeae Hartm. 1934 Scam. et Pass. 1959 in central Poland

The range of acidophilous oak forest from Quercetea robori-petraeae Br-Bl. et. Tx. ex Oberd. 1957 in Central Europe is not well known. It depends largely on the syntaxonomical concept used. According to many Polish authors acidophilous oak forest range finishes in central Poland and in the eastern part of the country they are replaced by oak-pine forest from Dicrano-Pinion alliance: Querco-Pinetum (W. Mat. 1981) J. Mat. 1988 and Serratulo-Pinetum (W. Mat. 1981) J. Mat. 1988 (i.e. Matuszkiewicz 1988; Matuszkiewicz and Matuszkiewicz 1996). According to other authors the acidophilous oak forests are present also in Eastern Europe (Mucina et al. 2016) and are reported for example from Ukraine (Goncharenko and Yatsenko 2020). According to polish authors, the acidophilous central European oak forest Calamagrostio arundinaceae-Quercetum petraeae (Hartm. 1934 Scam. et Pass. 1959) is the most continental association from Quercetea robori-petraeae class in Europe. Traditionally it was placed in Quercion roboris Malcuit 1929 (syn. Quercion robori-petraeae Br.-Bl. 1932) alliance (Matuszkiewicz 2008), but recently was moved to the Agrostio-Quercion petraeae Scamoni et Passarge 1959 (Kasprowicz 2010; Mucina et al. 2016), which gather the associations with most continental preferences. The knowledge about the distribution of Calamagrostio-Quercetum in central Poland is h elpful in understanding the distribution of the acidophilous oak forests from Quercetea robori-petraeae class in Europe.

The acidophilous central European oak forests Calamagrostio arundinaceae-Quercetum petraeae was firstly reported from Germany (Hartmann 1934; Scamoni 1961) and later from western Poland (Fabiszewski and Faliński 1967). The knowledge on the distribution of it was reviewed by Matuszkiewicz (1988); Matuszkiewicz and Matuszkiewicz (1996), but the eastern border of the association was determined by the Authors only provisionally. Range of the association in western Poland was broadly reviewed by Kasprowicz (2010). In addition, new stands of Calamagrostio-Quercetum were recently found in central Poland (i.e. Jakubowska-Gabara 1999; Koba 2012, 2013; Zaniewski et al. 2020), outside the provisional border determined by Matuszkiewicz (1988); Matuszkiewicz and Matuszkiewicz (1996). According to the brief review of distribution of the association in this part of the Country conducted by Zaniewski et al. (2020) the Calamagrostio-Quercetum tend to be more widespread association there and its range is at least several dozen kilometers wider. However the newly gathered data was only contributory and large gaps in the assumed distribution of the association were present.

The aims of this study were to survey and document new patches of Calamagrostio-Quercetum in central Poland, especially outside the acidophilous oak forest provisional range, to check the lower syntaxonomical units of the association and to present (cartogram) the correction of its provisional range in central Poland.

The study was based on field inventory of Calamagrostio-Quercetum (23 relevés within 10 stands located in central Poland) and on published data (524 relevés of Calamagrostio-Quercetum, Querco-Pinetum and intermediate communities).

We have chosen 10 localities of oak forest in central Poland in order to document Calamagrostio arundinaceae-Quercetum petraeae phytocoenoses. The fieldwork was conducted mainly at the beginning of vegetation seasons of 2017, 2018 and 2020. In case of stands located in Kampinos National Park, the exact sites were previously checked for the presence of early forest floor species few weeks before the main sampling conducted in summer. A set of 23 phytosociological relevés (circular shape, 400 m² each) was prepared in accordance with the principles of the Braun-Blanquet (1964) school, using the Barkman et al. (1964) scale. Cover was used as the measure of abundance. The value ‘rr’ was assumed as the smallest cover of species within relevé (corresponding to an area of about 0.01%), while the limit value between ‘r’ and ‘+’ was assumed to be a cover area of 0.5%. Species occurring outside the phytosociological relevé area were not recorded. Such a procedure was applied in order to obtain narrow cover-based intervals, characterized by relatively better behavior during numerical analysis (see Podani 2005, 2006; Maarel 2007).

Soil samples for laboratory analyses were collected from a depth from 0 to 20 cm measured from the top of the mineral organic matter horizon, from the central part of each phytosociological relevé. The soil samples were dried and divided. The skeletal and sand fractions were determined using the sieve method and compared using the divisions of Soil Science Society of Poland – PTG 2008 (Polskie Towarzystwo Gleboznawcze 2009). The second part was sifted through a 1 mm diameter sieve. The content of organic matter was determined by the loss on ignition method at 600°C, pH was measured using an electronic pH-meter in a distilled water solution using a standard ratio of 10:25. The information about other stand parameters, i.e. age of stand and site index of oak were obtained from Forest Data Bank – BDL (2020) Web Map Service (WMS).

The newly gathered phytosociological data was subjected to similarity analysis with typical Calamagrostio-Quercetum from Wielkopolska region (Kasprowicz 2010) and Querco-Pinetum and Serratulo-Pinetum from eastern Poland (Sokołowski 1963, 1976) phytocoenoses. Due to Calamagrostio-Querceum was also registered in the area of Kujawy region (Załuski 2011), the works by Kępczyński and Cyzman (1991, 1992) and Cyzman (1991) documenting the forest communities of Querco-Pinetum highly similar to communities from Quercetea robori-petraeae class were a lso taken into a ccount. Only two relevés strongly dominated by Quercus rubra (Kępczyński and Cyzman 1992) were excluded from this dataset. The last datasets accounted in the analysis were Calamagrostio-Quercetum stands recently described from southern Mazowsze (Koba 2012, 2013; Zaniewski et al. 2020) and intermediate with Querco-Pinetum association from Puszcza Kozienicka forest (Zaręba 1971). Phytosociological data was arithmetically transformed (Tüxen and Ellenberg 1937) before numerical processing which allowed comparison of data collected using scales of varying accuracy. All of the relevés (547) from these datasets were classified using Ward’s method. The average cover (Barkman’s TCV) and Phi coefficients (as a measure of species fidelity to the groups) were calculated for each of distinguished groups of relevés. The significance of Phi coefficients of species was checked with Fisher’s exact test, according to Chytrý et al. (2002). The obtained groups were assigned to associations on the basis of cover and fidelity of dominant and diagnostic species according to Matuszkiewicz (2008) and Kasprowicz (2010). The Ward’s analysis was carried out using PAST

4 software (Hammer et al. 2001). The average cover and Phi coefficients together with Fisher’s tests were conducted in JUICE 7 (Tichý 2002; Tichý and Holt 2006). The lower syntaxonomical units were manually assigned to the 23 relevés made in this study using subassociation concept developed by Kasprowicz (2010). The interpretation of this documentary table was based on the works by Matuszkiewicz (2008) and Kasprowicz (2010). The lack of an unequivocal diagnostic value of some of the plant species that coexist in the Calamagrostio-Quercetum association and mixed pine forest from Dicrano-Pinion alliance in central Poland was taken into account. The names of vascular plants were adopted after Mirek et al. (2002), mosses after Ochyra et al. (2003), liverworts after Szweykowski (2006) and lichens after Fałtynowicz and Kossowska (2016).

All of the newly documented stands of Calamagrostio-Quercetum were drawn on the map of the known distribution of the association in central and central-western Poland. The stands documented by Kępczyński and Cyzman (1991, 1992) and Cyzman (1991), classified as Calamagrosio-Quecetum in this analysis were also added to the map. The work by Kasprowicz (2010) was accounted as the basis of the known distribution of Calamagrostio-Quercetum in the western part of the analysed area and the summary by Zaniewski et al. (2020) for the eastern part of it. The ATPOL grid (Zając 1978; Komsta 2016) was used as a cartogram. The map was prepared using QGIS 3.14 software (QGIS Development Team 2021).

Patches of Calamagrostio-Quercetum association were documented with 23 relevés within 10 stands (located within 8 ATPOL grid cells). Ward’s Classification of all 547 relevés revealed three well distinguishable groups (Tab. 1).

The first one (A) consisted mostly of relevés representing Calamagrostio-Quercetum from Wielkopolska region, relevés from southern Mazowsze region, Querco-Pinetum “resembling Quercetea robori-petraeae” from Kujawy region and part of specific Querco-Pinetum typicum (intermediate with Calamagrostio-Quercetum) dataset from Puszcza Kozienicka forest. Most of relevés from present study was also classified within this group (Tab. 1). The group A represented Calamagrostio-Quercetum association with Quercus petraea, Calamagrostis arundinacea and Convallaria majalis being one of the best diagnostic species (Tab. 2).

The second group (B) consisted of relevés representing especially Calamagrostio-Quercetum from Wielkopolska region and specific communities resembling acidophilous forests, previously classified as Querco-Pinetum from Kujawy region. The last remaining relevé from this study was also classified here (Tab. 1). This group also represented Calamagrostio-Quercetum association and is significantly characterized for example by Quercus robur, Holcus mollis and Carex pilulifera (Tab. 2).

The third group (C) consisted of especially Querco-Pinetum relevés from Puszcza Kozienicka forest and Querco-Pinetum and Serratulo-Pinetum relevés from eastern Poland and represented Querco-Pinetum association. The remaining three relevés from the dataset from Kujawy region were also classified here (Tab. 1). This group represented Querco-Pinetum association and can be distinguished, inter alia, by dominance of Pinus sylvestris, Vaccinium myrtillus and Pleurozium schreberi (Tab. 2).

Three subassociations were identified within surveyed stands: polygonatetosum, typicum and molinietosum (Tab. 3). Patches of them were found also outside the provisional range, especially in the most distant (ATPOL grid cell ED14) research site in Kampinos National Park (Fig. 1).

Figure 1

The age of dominant tree species in studied sites varied from 51 to 110 years, oak site index from I to III. Forest site types varied highly in fertility (from coniferous to deciduous sites) and much less in humidity (mostly semixeric and rarely wet sites). Brunic arenosols (typical and brown rusty soils) predominated as a soil subtype (Tab. 4).

All of the 23 relevés from this study did join with Calamagrostio-Quercetum groups A and B (Tab. 1) as well as most of the relevés by Cyzman (1991), Kępczyński and Cyzman (1991, 1992). This means that acidiophilous oak forests are present in central Poland. However it cannot be concluded, that the boundary of the association range is highly probable there. Due to only the move of the provisional range of Calamagrostio-Quercetum in central Poland by circa 60–90 km to the north-east is proposed. It should include nearly whole south-western part of Mazovia, approximately as far as the Vistula river line.

All three subassociations described by Kasprowicz (2010) were identified in the new stands surveyed in central Poland (Table 2). Patches of Calamagrostio-Quercetum polygonatetosum, typicum and molinietosum were found especially in Rózin range, Kampinos National Park (ATPOL grid cell ED14). In this study (Fig. 1) it is the most distant place (nearly 90 km) from the provisional range of the minor role of the association in the landscape proposed by Matuszkiewicz (1988), Matuszkiewicz and Matuszkiewicz (1996). Patches of Calamagrostio-Quercetum polygonatetosum differentiated by presence of many species, often together with bit higher cover of lily of the valley Convallaria majalis L. and wall hawkweed Hieracium murorum L. (Tab. 3). There was also noted relatively higher frequency of species from heathlands (Nardo-Callunetea). Calamagrostio-Quercetum molinietosum could be well distinguished with a high cover of purple moor-grass Molinia caerulea (L.) Moench and presence of common oak Quercus robur L. together with sessile oak Q. petraea ( Matt.) Liebl. within tree stand. T he h ighest values of common bilberry Vaccinium myrtillus L. cover were usually noted here. The differentiated subassociations corresponded well with the internal variation of Calamagrosio-Quercetum described by Kasprowicz (2010) from Wielkopolska.

All of the soil subtypes occurring within researched patches – Brunic Arenosols (brown and typical rusty soils), typical brown soils, Haplic Luvisols, Albic Brunic Arenosols and Gleyic Albic Podzols (Tab. 3) were also recorded in Calamagrostio-Quercetum stands in other parts of Poland (i.e. Lasota et al. 2005; Rutkowski and Maciejewska-Rutkowska 2007; Lasota 2013). The measured pH of upper soil horizons of the researched stands was usually similar or slightly higher than in western Poland (Lasota et al. 2005; Lasota 2013). The average share of carbon in organic matter is about 58% (Nelson and Sommers 1982). Due to the organic carbon content in the examined patches was from 0.8 to 3.8% and was relatively similar to other areas of acidophilous oak forests in western Poland (Lasota 2013). Oak site index of researched patches was mainly in II class, rarely I or III one (Tab. 3). This is similar or slightly higher than in other parts of Poland (Lasota et al. 2005).

Although Fabiszewski and Faliński (1967) mentioned the occurrence of impoverished communities resembling Calamagrostio-Quercetum from vicinity of Łódź, acidophious oak forests were not registered in central Poland nearly to the end of the XXth century. The concept of degeneration and synatropization of plant associations was under development (Faliński 1966, 1972; Olaczek 1974) and the correct diagnosis of Calamagrostio-Quercetum could be difficult (Kasprowicz 2010). As a result, patches of acidophilous oak forests with antropogenically introduced Scots pine Pinus sylvestris L. could often be classified as mixed coniferous forests (Kasprowicz 2010). This was also the reason why the eastern boundary of range of Calamagrostio-Quercetum was only approximated (Matuszkiewicz 1988; Matuszkiewicz and Matuszkiewicz 1996). This state was also reflected in the concept of including specific sessile oak-pine forests occurring in central Poland within association Quercetum sessiliflorae (petraeae?)-Pinetum as a new name proposal for Pino-Quercetum Kozł. 1925 em. Mat. et Pol. 1955, presented by Zaręba (1988). The proposal was a result of division Querco roboris-Pinetum into moist oak-pine forests as Populo tremulae-Quercetum in the sense of Sokołowski (1968, 1980) and not wet oak forest with pine as a Pino-Quercetum. What is even more important, Zaremba (1988) stated, that well preserved patches of such an oak forest with pine admixture are present in central Poland, for example in Puszcza Kozienicka forest, Kampinos National Park and Włocławek-Gostynin Forest areas. Patches of Calamagrosio-Quercetum in Puszcza Kozienicka forest were recently identified by Koba (2012, 2013). The presence of acidophilous oak forest in Kampinos National Park was confirmed directly in this study (Fig. 1, Tab. 2, 3, 4). The presence of this association in Włocławek-Gostynin Forest area was also confirmed here in the carried out Ward’s classification (Tab. 1, 2, Fig. 1). This suggest that ecological succession from mixed sessile oak-pine forests into acidophilous oak forests at the landscape level probably occurs in central Poland. The another possible way of progression of Calamagrosio-Quercetum may be a result of decline Potentillo albae-Quercetum phytocoenoses. Such a process was registered so far only in western Poland (Jakubowska-Gabara 1996), however the Calamagrosio-Quercetum stands registered in Petrykozy site (Fig. 1, ATPOL grid cell ED54) are located in the same small forest complex as in the case of old stands of Potentillo albae-Quercetum surveyd by Jakubowska-Gabara (1985). Due to the possible origin of Calamagrosio-Quercetum as a result of Potentillo albae-Quercetum decline, such a phenomenon cannot by excluded also in central Poland. This issue however cannot be sold in this analysis and additional studies are needed. From the other site regression of Calamagrostio-Quercetum patches within landscape scale was reported recently from Kujawy region (Załuski 2011). Cyzman (2010) stated, that acidophilous oak forest phytocoenoses in the area of Gostynin-Włocławek Forest are degenerated forms of oak-hornbeam forests. Due to it is possible that Calamagrostio-Quercetum in central Poland may not only be the actual and in some cases even potential forest community, but also the part of a longer successional series, beginning from oak-pine forests and finishing in deciduous hornbeam forests.