[in Polish with English summary: ] The Kampinos Forest complex, in which in the years 1960-1963 lichenological investigations were carried out, lies in the Mazowsze province in the wide Vistula old valley (ice-marginal streamway), occupying the region between the western border of the city of Warsaw and the river Bzura. In the forest two bands of soaken meadows and marshes running in parallel direction and occupying the old river bed may be distinguished. They alternate with bands of dune areas. It was the sandy dunes that constituted the main object of investigation. In a great part they are overgrown with pine and mixed forests, the remaining areas are bare and undergone to the process of blowing up the soil. Numerous species of xerothermic psammophilous plants grow on the dunes. Among these cryptogams are of great importance, and in the first place mosses and lichens. The aim in view was to characterize the flora and lichen communities against the general vegetative cover, and namely, investigation of epiphytic lichens of the more important trees and shrubs, elaboration of the ground lichens with special reference to their contribution to the fixing of soil and forming of vegetative cover on the dunes, and compilation of a possibly full list of the lichens of the Kampinos Forest. The investigations of the epiphytic flora were extended to almost all the trees and shrubs growing in the Forest. The lichens occurring on eleven of them are listed in the table. It appeared that numerous epiphytic lichen species are specific for groups of trees with a related physical structure or chemical properties of the bark, e.g. on the soft, peeling off bark of Betula verrucosa and Pinus silvestris numerous acidophilous lichens with a scalelike and foliose thallus occur, whereas on poplars and willows, numerous nitrophilous and neutrophilous species are found. The epiphytes specific for deciduous forest trees are grouped on Quercus robur, Alnus glutinosa, Carpinus betulus and Fraxinus excelsior. Also a large group of eurychoric lichens occurring commonly on various both deciduous and coniferous tree species were found. In the epiphytic communities seven associations belonging to five orders were distinguished. On the basis of their floristic similarity they are divided into two groups. The first comprises the associations: Physcietum ascendentis, Parmelietum caperatae and Phlyctidetum argenae. They all include a numerous group of common species frequently exhibiting a high constancy. In this group the first montioned association, Physcietum ascendentis, occurs most frequently on willows and poplars growing along roads. This association exhibits most numerous distinctive characteristics; the abundantly occurring nitrophilous and neutrophilous species were not noted in other associations. The two remaining associations of this group, Parmelietum caperatae and Phlyctidetum argenae occurring in moist forests on the bark of alders, ashes and oaks are floristically much closer related to each other. The srcond group comprises the four remaining associations growing on pine and birch bark in pine and mixed forests: Psoretum ostreatae, Parmelietum furfuraccae, Parmeliopsidetum ambiguae and Chaenothecetum melanophaeae. The first, Psoretum ostreatae, is of xerophilous character and develops exuberantly in the Kampinos Forest in its typical form. The further two associations Parmelietum furjuraceae and Parmeliopsidetum ambiguae which reach their optimum in the mountain and submontane regions of Europe appear in the Forest in their most xerophilous form. Particular attention was devoted to ground lichens and especially to their psammophilous forms. In the investigations of the ground vegetation, the lichens were not singled out into separate communities but treated as components together with flowering plants, bryophytes and algae. In multilayer communities the patches of bryophyte-lichen vegetation were considered as ground synusia. Phytosociological records of the ground-layer patches were prepared by the Braun-Blanquet method on small surface areas (1 m²). This allowed not only to distinguish new interesting communities, but also to reveal even slight changes in the floristic composition and to demonstrate the possible lines of succession in the transition from xerothermic communities of open areas to coniferous communities. From among the ground communities rich in lichens two associations, three varieties of communities and four not definitely classified communities were distinguished. In the table listing ground communities (Table 19) three groups more or less distinct may be distinguished: 1) psammophilous associations and communities developing strongly on sunny open dune areas, 2) communities of intermediate character constituting various stages leading from psammophilous communities of open areas to the ground layer of pine forests, 3) a well developed forest ground layer in Cladonia pine forest. The first group includes the association Corynephoretum canescentis cladonie-tosum in which I have distinguished two variants: var. Stereocaulon condensatum and var. Stereocaulon incrustatum and the community Diploschistes bryophilus. They all exhibit a xerothermic character and play an important role in fixing sands. Species of the alliance Corynephorion dominate here and species characteristic of Corynephoretum canescentis cladonietosum with a small contribution of representatives of other phytosociological groups. The second group comprises: the association Corynephoretum canescentis cladonietosum var. Cladonia rangiformis and the communities: Lecidea sp. diversae, Cladonia mitis - Cladonia rangiferina, Cladonia cornutoradiata - Cladonia bacil-laris. They all are of intermediate character and constitute various stages leading to the formation of the ground layer of pine forests. The contribution of species from the alliance Corynephorion markedly decreases here, and the number of coniferous forest elements increases; species associated with this group are also quite numerous. To the third group belongs only the well developed forest ground layer of Cladonio-Pinetum. Comparison of the vegetation of the pine forest ground layer with that of open dune areas allowed to distinguish a group of pine forest lichens which occur only in Cladonio-Pinetum and some intermediate communities. They are found neither in mossy pine forests nor in communities of open areas. The following lichens may be considered as local species characteristic of the Cladonio-Pinetum: Cladonia rangiferina, CI. sylvatica, CI. gracilis, CI. tenuis, CI. furcata, CI. cornuta, CI. alpestris. Their distinction confirms the existence of the association Cladonio--Pinctum as a local association which has been distinguished in the Kampinos Forest by R. Kobendza (1930) under the name Pineto-Clodonietum. This association corresponds to the subassociation Peucedano-Pinetum cladonietosum established by Matuszkiewicz (1962). Probably the succession of communities rich in ground lichens progresses from primitive psammophilous communities of initial character over the well developed association Corynephoretum canescentis cladonietosum and communities of intermediate character to the pine forest ground layer. On bare dune sands Coryna-phoretum canescentis cladonietosum var. Sterocaulon inscrustatum and var. Stereo-caulon condensatum and the communities Diploschistes bryophilus and Lecidea sp. diversae, which are well adapted for fixing mobile sands chiefly, owing to the abundant psammophilous forms of lichens growing in them, play a pioneer role here. These communities may transform to a typical Corynephoretum canescentis cladonietosum, an association frequently found on open dune areas in the Kampinos Forest. On non afforested areas it is of a long-lasting character, whereas after afforestation it transforms into a Cladonia mitis - Cladonia rangijerina community of short duration which in time develops into the ground layer of Cladonio--Pinetum. Cladonio-Pinetum growing on poor in nutrients, sandy soils particularly on dune ridges is a durable association exhibiting no tendency to transformation into a pine forest with a moss or moss-blackberry ground cover. Only on more humid, richer soils does it transform in time into a mossy pine forest, however the latter develops more frequently from more primitive communities. In the area investigated mossy pine forest develops often from the community Cladonia cornutoradiata - Cladonia bacillaris which is rich in species growing in coniferous forests and shows no tendency to transforming into a Cladonio-Pinetum ground layer. Its specific composition gives reason to suppose that it transforms into a mossy or moss-blackberry ground layer with a large proportion of Dicranum undulatum and Entodon schreberi. Besides the progressive succesion, also regressive processes take place here (marked in Fig. 63 by dashed lines) connected with the devastation of the forest vegetation or felling of parts of the forest in compliance with the management plane, or else with the depression of the ground water level. These processes lead to the development on these areas of postsilvatic more primitive communities with a high proportion of crustose or scaly-fruticose lichens. They frequently transform to the community Corynephoretum canescentis cladonietosum. In the course of the investigations special attention was devoted to the psammophilous lichens playing a pioneer role in the settling and fixing of mobile sands. Among these lichens four basic groups were distinguished differing rather widely in their biological properties. Fruticose lichens very loosely bound with the substratum. Their thalli are easily detached from it and may be carried away by wind. They are trapped by more prominent parts of the terrain or by plant tufts. A typical representative of this group is Cornicularia aculeata. Similar forms occur also in Cladonia mitis, CI. uncialis and Cetraria islandica. Fruticose lichens with an early disappearing primary thallus. They are stronger bound with the substratum so that the thallus cannot be carried away. Their rather loosely standing slender styles are generally overblown with sand. A typical representative of this group is Stcreocaulon incrustatum. Lichens with consistently dimorphic thallus with predominance of scaly--nodular elements and relatively few styles. They generally develop almost on the surface of the substratum inhibiting early eolic processes. To this group Stereocaulon condensatum, Cladonia verticillata var. cervicornis, CI. foliacea var. alcicornis and CI. pleurota were classified. 4. Lichens with crustose thalli. This group exhibits most diversified forms. Lecidea granulosa forms compact extensive crusts. Diploschistes bryophilus occurring in forms similar to those of the preceding species also develops on a loose substratum small thalli rounded in outline, somewhat convex in the middle which are easily carried away by the wind. The thallus of Lecidea humosa var. chthono-blastes has the form of a convex rosette in which the loose weft of the fungal hyphae, penetrates rather deep into the substratum. The lichen flora of the Kampinos Forest is not rich in species. Within the whole area 146 species have been recorded without counting numerous varieties and forms. From among the species seldom found in Poland the following occur here: Verrucaria controversa, Staurothele jrustulena, Arthothelium spectabile, Bacidia flavovirescens, Cladonia papillaria, Arthonia radiata and the rarely met forms of common species: Cetraria crispa var. prorumpens and Cladonia mitis var. soralifera. Species rare in the lichen flora of Mazowsze are represented here by Parmelia bitteriana, Cladonia impexa, CI. turgida, Baeomyces roseus, Lecania cyrtella, Usnea julvoreagens. In the species earlier reported from this area or preserved in herbaria, I did not find among others Lobaria pulmonaria and Parmelia scortea. Many of the herbarium specimens collected earlier exhibit much better developed thall than those collected at present (e.g. Anaptychia ciliaris, Evemia prunastri). This would be evidence of a certain deterioration of the lichen flora in the Forest. Its reasons may be sought in the severe devastation of the forests during the two world wars, the lowering of the ground water level which occurred owing to the construction of drainage canals and to the increasing influence of the extending city of Warsaw and its large industrial plants some of which are situated in the nearest neighbourhood of the Forest.