The loss of pristine forest landscapes due to intensive management has altered forest carbon dynamics and caused a decline in biodiversity. The carbon balance of unmanaged forests is insufficiently known due to a lack of repeated measurements. Moreover, the links between the conservation of threatened species and forest carbon dynamics are poorly explored. We examined the carbon balance of boreal unmanaged forests based on three repeated tree surveys conducted in 27 unmanaged Finnish coniferous-dominated forest stands in 1990–2019. We also surveyed nationally red-listed epiphytic lichens and explored the linkages between carbon dynamics, forest naturalness, and epiphytic lichen occurrence. On average, net primary production increased by 10.7

The loss of pristine old-growth boreal forest landscapes due to the intensive management for timber production has caused both a severe decline of forest biodiversity in Northern Europe as well as significantly altered their carbon stocks and dynamics. Understanding of the dynamics of old-growth forests is needed to evaluate the consequences of different forest management and conservation strategies on climate change mitigation and biodiversity conservation. It is increasingly suggested that integrated forest management and conservation planning is required to secure both biodiversity and carbon storage values. However, it is insufficiently known how closely these values coincide at the local level, i.e., whether the same structural and quality features in old-growth forests support both high biodiversity and carbon stock.The objectives of this study were, first, to explore the dynamics of stand growth and carbon sequestration in boreal old-growth forests and second, to investigate whether the occurrence of red-listed epiphytic forest lichens coincides with high carbon stock and structural features related to it. The study was based on an extensive repeated forest inventory dataset collected between 1990 and 2019 in southern Finland and a lichen inventory conducted during 2020 – 2021 at the same sites.The estimated volume of standing trees and deadwood were higher in the studied forest stands than in managed forests on average. Estimates of net primary production showed varying trends of carbon sequestration among the study plots. Stand gross growth increased by 50% during the study period. The standing volume remained stable because a large proportion of the biomass increment was allocated to deadwood. The study sites showed a high occurrence of red-listed epiphytic lichens. No relationship was found between the species richness of red-listed lichens and the aboveground carbon stock. However, a significant negative relationship was found between the number of red-listed lichen occurrences and carbon stock. The species richness of red-listed lichens showed a strong unimodal response to the aboveground carbon stock change: the highest species richness was associated with intermediate carbon sinks.Our results highlight the major role of tree mortality driving the carbon dynamics of old-growth forests, with simultaneous benefits for deadwood-associated species. However, more research is needed on the stability of carbon stocks of forests in the face of shifting disturbance regimes due to climate change. While the species richness of red-listed epiphytic lichens had a neutral relationship with the aboveground carbon stock size, we observed fewer occurrences in carbon-rich forests, and lower species richness and occurrences in plots with large carbon sinks. Therefore, if climate benefits are sought with methods that increase stand density, negative impacts may be expected on lichen species that fare poorly in dense stands with low light. Additionally, high carbon sequestration in fast-growing stands may come at the expense of reduced biodiversity.In summary, this study supports the idea that old-growth forests provide considerable benefits regarding both climate change mitigation and biodiversity. Therefore, increasing the area of old-growth forests would simultaneously support these key goals.

The taxonomy of Protoblastenia in Finland was studied, based on morphology and molecular data (nuITS rDNA sequences). Twenty species were recognised, with sixteen species being newly described here: P. arupii sp. nov., P. borealis sp. nov., P. compressa sp. nov., P. dolomitica sp. nov., P. ekmanii sp. nov., P. fennoarctica sp. nov., P. minuta sp. nov., P. oulankaensis sp. nov., P. pseudocompressa sp. nov., P. pseudoterricola sp. nov., P. remota sp. nov., P. rikkinenii sp. nov., P. saanaensis sp. nov., P. timdalii sp. nov., P. violacea sp. nov. and P. westbergii sp. nov. All species are confined to calcareous rocks, except P. terricola which also grows on calcareous soil. The calcareous fells in Enontekiö in NW Finland were identified as hot spots of Protoblastenia diversity. Nine newly-described species (P. arupii, P. fennoarctica, P. minuta, P. pseudoterricola, P. rikkinenii, P. saanaensis, P. timdalii, P. violacea and P. westbergii) are restricted to this area in Finland. Several of the species are semi-cryptic. On average, they may have minor morphological differences, but many specimens cannot be identified, based on morphology only. Protoblastenia rikkinenii is reported from Norway and P. oulankaensis from Italy, based on GenBank sequences. Full descriptions and a preliminary key of Protoblastenia in Finland are provided.

Seven new species of Verrucaria are described from Finland: Verrucaria hakulinenii sp. nov., V. juumaensis sp. nov., V. linkolae sp. nov., V. lohjaensis sp. nov., V. norrlinii sp. nov., V. oulankajokiensis sp. nov., and V. vainioi sp. nov. Verrucaria linkolae is also reported from the Czech Republic, Germany and the United Kingdom, V. norrlinii from Norway and V. juumaensis from Canada based on a previously unidentified soil sample. Based on ITS sequences, V. hakulinenii and V. juumaensis probably belong to the Verrucaria hydrophila group whereas V. linkolae, V. norrlinii, V. oulankajokiensis and V. vainioi are closely related to V. hunsrueckensis and V. nodosa. The new species are characterized by a thin brown or green thallus, rather small perithecia and a predominantly thin involucrellum reaching the exciple base level. Verrucaria hakulinenii is characterized by a thin thalline cover of the perithecia, a green thallus and fairly large spores (18-22 x 8-10 mu m). Verrucaria juumaensis, V. linkolae, V. norrlinii and V. vainioi are characterized by a predominantly brown thallus, often with goniocyst-like units. Verrucaria linkolae has densely occurring perithecia (100-330 perithecia per cm2) whereas in V. juumaensis, V. norrlinii and V. vainioi perithecia occur more sparsely (40-160 perithecia per cm2). Verrucaria juumaensis and V. vainioi usually have a minute thallus. Verrucaria juumaensis differs from V. vainioi by slightly larger perithecia (0.18-0.27 mm diam.) and longer and wider spores. Verrucaria lohjaensis is characterized by a mosaically dark brown and white, small areolate thallus and conspicuous ostioles. Verrucaria oulankajokiensis has small perithecia that are often thinly covered by thalline tissue and a thallus partly surrounded by dark lines. Most species occur on calcareous rocks, but V. vainioi is restricted to siliceous rocks. Verrucaria linkolae and V. norrlinii are widely distributed both on calcareous, serpentine and siliceous rocks, preferring pebbles. Epiphytic occurrences of V. linkolae and V. norrlinii are confirmed. A key to the new species and species with a similar morphology in Finland is provided.

The Finnish red list shows that the epiphytic lichen flora of Finnish forests is highly threatened and declining steeply. Red lists provide limited information on the habitat associations of threatened species, which could be relevant in informing management and conservation measures. We used documented empirical data and expert assessments to determine for each red-listed (IUCN categories Near Threatened, NT; Vulnerable, VU; Endangered, EN; Critically Endangered, CR; Regionally Extinct, RE) epiphytic lichen species of Finland the following key habitat associations: host tree species, substrate type, habitat type, geographical distribution, preferred microclimate, and minimum required forest and tree age. The most important host tree species were Picea abies (L.) H. Karst. and Populus tremula L. Other tree species of high importance included Sorbus aucuparia L. and Salix caprea L. One fourth of red-listed epiphytic lichens were primarily lignicolous. Most species required old-growth forests (required by 41% of species) or old trees (52%), but many species required only mature forests (36%) or trees (35%). The microclimatic preferences of most red-listed epiphytic lichens consisted of high or intermediate light availability and humidity. Most species whose status had deteriorated were dependent on deciduous trees. The continuous availability of old deciduous trees (especially Populus, Salix and Sorbus) requires special attention in both managed and protected forests. Red-listed epiphytic lichens would be aided by increased forest protection or transitioning to less intensive management regimes.

The taxonomy of lichen species morphologically similar to Thelidium auruntii and T. incavatum in Fin-land is being revised. Based on ITS and morphology, ten species occur in Finland. All species are re-stricted to calcareous rocks. The Thelidium auruntii morphocomplex includes six species: T. auruntii, T. huuskonenii sp. nov., T. pseudoauruntii sp. nov., T. sallaense sp. nov, T. toskalharjiense sp. nov. and T. sp. 1. In the ITS phylogeny, T. auruntii, T. pseudoauruntii and T. sallaense group together, but the remaining species are placed outside of this clade. All the species have northern distribution in Finland, occurring on fells in NW Finland and/or in gorges in the Oulanka area in NE Finland. The Thelidium in-cavatum morphocomplex includes four species: T. declivum sp. nov., T. incavatum, T. mendax sp. nov. and T. sp. 2. This morphogroup is not resolved as monophyletic in the ITS phylogeny, with only T. declivum and T. mendax forming a strongly supported group. Thelidium incavatum is rather common in SW Fin-land, with one separate locality in eastern Finland. Thelidium declivum occurs only in the Oulanka area. Thelidium mendax occurs in the Oulanka area, but one locality is known from eastern central Finland. Thelidium sp. 2 is known from one locality in SW Lapland.

In boreal forests, European aspen (Populus tremula L.) is a keystone species that hosts a variety of accompanying species including epiphytic lichens. Forest management actions have led to a decrease in aspen abundance and subsequent loss of suitable habitats of epiphytic lichens. In this study, we evaluate the environmental responses of epiphytic lichen species richness and community composition on aspen, focusing on the potential of remote sensing by combined hyperspectral imaging and airborne laser scanning to identify suitable habitats for epiphytic lichens. We measured different substrate and habitat parameters in the field (e.g., aspen diameter and bark pH) and by remote sensing (e.g., mean canopy height and tree species composition of the surrounding forest) in the study area in Southern Finland that includes protected and non-protected forest. We used linear regression and the Hierarchical Model of Species Communities (HMSC) to compare how the different parameters explain and predict lichen species richness and community composition, respectively. We show that coarse predictions of epiphytic lichen community composition can be made using parameters extracted from remote sensing data. Estimated mean canopy height, tree density, dominant tree species and tree species diversity of the stand predicted the species community on aspens slightly better than field parameters. Remote sensing variables calculated over a larger area (30 m radius) always outperformed the same variables calculated over a smaller area (10 m radius) in predicting community composition, highlighting the cost-efficiency of remote sensing compared to covering a similar area with on-ground measurements. These results are encouraging for the prospects of using remote sensing data to direct field inventories and to map potential high-biodiversity habitats. Aspen bark pH was the only parameter affecting species richness regardless of whether the forest was protected or not, whereas, interestingly, the effects of tree diameter, height and furrow depth were only significant in protected areas. Our results also underline the importance of protected areas, since they hosted a higher tree-specific number of epiphytic lichen species, and red listed species, than non-protected areas.

Questions Aspen (Populus tremula) is declining in the old-growth forests of boreal Fennoscandia. This threatens the numerous taxa that are dependent on old aspens, including many epiphytic lichens. Potential methods to aid epiphytic lichens on aspen are centered around treatments which affect the density of Norway spruce (Picea abies). In this study, we investigated how epiphytic lichen communities on aspen are affected by the variation of spruce density in the immediate vicinity of the focal aspen. Location Southern boreal forests in Finland. Methods We recorded the occurrence of lichens from 120 aspens in 12 semi-natural forest sites. We used spruce basal area as the measure for spruce density. The selected aspens represented a gradient in spruce basal area in the vicinity of the aspen from 0 to 36 m(2)/ha. We also measured other tree- and stand-level variables that are known to influence lichen occurrence. Results Lichen communities on aspen were affected by spruce density, stand age and bark pH. Both lichen species richness and the richness of red-listed species were highest at an intermediate spruce density, and both increased with stand age. Lichen species richness was higher when bark pH was lower. Additionally, community composition was influenced the most by spruce density, followed by bark pH. Conclusions Our study highlights the detrimental effects of high spruce density on lichen diversity on aspens. This is caused by high spruce density resulting in low light availability. Lichen diversity on aspens was highest when spruce density was intermediate. Spruce thinning in aspen-rich old-growth forests can be helpful in ensuring the long-term persistence of old-growth lichens on aspen in protected forests.

[This corrects the article DOI: 10.3897/mycokeys.72.56223.].

European aspen (Populus tremula L.) is a keystone species in boreal forests that are dominated by coniferous tree species. Both living and dead aspen trees contribute significantly to the species diversity of forest landscapes. Thus, spatial and temporal continuity of aspen is a prerequisite for the long-term persistence of viable populations of numerous aspen-associated species. In this review, we collate existing knowledge on the ecological role of European aspen, assess the knowledge needs for aspen occurrence patterns and dynamics in boreal forests and discuss the potential of different remote sensing techniques in mapping aspen at various spatiotemporal scales. The role of aspen as a key ecological feature has received significant attention, and studies have recognised the negative effects of modern forest management methods and heavy browsing on aspen occurrence and regeneration. However, the spatial knowledge of occurrence, abundance and temporal dynamics of aspen is scarce and incomprehensive. The remote sensing studies reviewed here highlight particularly the potential of three-dimensional data derived from airborne laser scanning or photogrammetric point clouds and airborne imaging spectroscopy in mapping European aspen, quaking aspen (Populus tremuloides Michx.) and other Populus species. In addition to tree species discrimination, these methods can provide information on biophysical, biochemical properties and even genetic diversity of aspen trees. Major obstacles in aspen detection using remote sensing are the low proportion and scattered occurrence of European aspen in boreal forests and the overlap of spectral and/or structural properties of European aspen and quaking aspen with some other tree species. Furthermore, the suitability of remote sensing data for aspen mapping and monitoring depends on the geographical coverage of data, the availability of multitemporal data and the costs of data acquisition. Our review highlights that integration of ecological knowledge with spatiotemporal information acquired by remote sensing is key to understanding the current and future distribution patterns of aspen-related biodiversity.

Species of Verrucaria, characterised by large spores (at least some spores exceeding 25 µm in length), perithecia leaving pits in the rock and a pale thin thallus, form a taxonomically-difficult and poorly-known group. In this study, such species occurring in Finland are revised, based on ITS sequences and morphology. Maximum likelihood analysis of ITS sequence data was used to examine if the species belong to the Thelidium group, as suggested by BLAST search. Twelve species are accepted in Finland: Verrucaria bifurcata sp. nov., V. cavernarum sp. nov., V. devergens, V. difficilis sp. nov., V. foveolata, V. fuscozonata sp. nov., V. karelica, V. kuusamoensis sp. nov., V. subdevergens sp. nov., V. subjunctiva, V. subtilis and V. vacillans sp. nov. Verrucaria foveolata is nested in V. subjunctiva in the phylogeny, but due to morphological and ecogeographical differences, the two taxa are treated as separate species pending further studies. Based on the analysis, the study species belong to the Thelidium group. The studied species show a rather high infraspecific morphological, but a low genetic variation. Furthermore, they show considerable overlap in their morphology and many specimens cannot be reliably identified, based on morphology only. All species are restricted to calcareous rocks. Verrucaria alpigena, V. cinereorufa and V. hochstetteri are excluded from the lichen flora of Finland. Verrucaria grossa is considered a species with unresolved identity. Verrucaria foveolata and V. subtilis are rather common on calcareous rocks of Finland while V. devergens and V. kuusamoensis are restricted to northern Finland. Verrucaria subjunctiva occurs mainly in northern Finland. Verrucaria bifurcata has been found only from southern Finland. Verrucaria difficilis has few localities both in SW and NE Finland. Verrucaria vacillans is restricted to calcareous rocks (dolomite) on the mountains of the NW corner of Finland. Verrucaria fuscozonata, V. karelica and V. subdevergens occur only in the Oulanka area in NE Finland. A lectotype is designated for V. subjunctiva. The morphology of the Finnish species was compared with 51 European species of Verrucaria presumably belonging to the Thelidium group.

Why populations of threatened species disappear is among the key questions in conservation biology. However, very few local and regional studies have attempted to quantify the importance of the various causes. In this investigation, the status of the populations of threatened vascular plants, bryophytes and lichens found between the years 1860–1979 in a national biodiversity hot spot in SW Finland was studied during the years 1990–2008. Of the populations, 82% had disappeared and 18% were re-discovered. The disappearance rate of populations differed between habitats: exceeding 80% in most habitat types whilst being lowest on rock outcrops (58%). Complete destruction of all locally suitable habitats was the main reason for the disappearance of the populations (73%) concerned. Habitat deterioration (including partial habitat loss) was identified as the reason for the disappearance for 22% of the populations. Only for 5% of the populations could it not be revealed whether habitat quality had changed or not, but deterioration of habitat quality or habitat loss is possible even in these cases. For none of the disappeared populations was no change in habitat quality verified. In most cases, habitat loss and deterioration were caused by agriculture or forestry. These results support the conclusion that vascular plant, bryophyte and lichen populations in the boreal landscape have disappeared directly because their habitats have disappeared, declined in size or deteriorated due to forestry, agriculture, construction, mining and pollution. More subtle changes in habitat quality, fragmentation, problems related to small population size per se and other reasons may have contributed to only a few disappearances of local populations. The disappearance rate was similar between the study groups, but the relative importance of reasons for disappearance was different. The results emphasize the importance of habitat protection for threatened vascular plants, bryophytes and lichens.

Metsien avainbiotooppien merkitystä epifyyttijäkälille selvitettiin kirjallisuuskatsauksen avulla. Avainbiotooppien merkitys riippuu siitä, miten ne määritetään sekä kuinka hyvin ne tunnistetaan ja jätetään hakkuiden ulkopuolelle. Avainbiotooppikäsite on potentiaalisesti hyvä epifyyttijäkälille tärkeiden metsien säästämisessä. Eri avainbiotooppityyppien merkitys epifyyttijäkälille on varsin erilainen. Puuston korkea ikä on vaateliaiden epifyyttijäkälien kannalta tärkein muuttuja. Tutki­musten mukaan avainbiotooppikäsitteen soveltaminen ei ole onnistunut hyvin. Suurimmat ongelmat ovat kohteiden tunnistamisessa, säästämisessä sekä niiden pienessä koossa. Hakkuiden ja pienen koon takia vaateliaiden epifyyttijäkälien esiintymien häviämiset ovat olleet avain­biotoopeilla varsin tavallisia. Häviämistä lisäävät ilmansaasteet ja ylisuuri hirvieläinkanta, joka estää lehtipuiden uusiutumista avainbiotoopeilla. Samat tekijät, jotka aiheuttavat populaatioiden häviämistä, estävät myös uusien jäkäläpopulaatioiden leviämistä avainbiotoopeille. Tässä katsauksessa käsiteltyjen tutkimusten perusteella voidaan arvioida, että jos avainbiotoopit säästettäisiin kaikilta hakkuilta, ilmanlaatua saataisiin parannettua ja hirvieläinten määrää voimakkaasti vähennettyä, suuri osa uhanalaisista jäkälistä voisi säilyä avainbiotoopeilla. Yhdessä riittävän suojelualueverkoston kanssa avainbiotoopit voisivat olla tehokas tapa epifyyttijäkälien monimuotoisuuden säilyttämisessä. Suomessa käytettyä avainbiotooppien määrittelyä on tarpeen korjata vastaamaan muissa maissa käytettyä uhanalaisen lajiston esiintymisen todennäköisyyttä painottavaa tulkintaa sen sijaan, että korostettaisiin kohteen pienialaisuutta.

Abstract In this study we clarify the phylogeny and reassess the current taxonomy of the Micarea prasina group, focusing especially on the M. byssacea and M. micrococca complexes. The phylogeny was investigated using ITS, mtSSU and Mcm7 regions from 25 taxa belonging to the M. prasina group. A total of 107 new sequences were generated. Data were analyzed using maximum parsimony and maximum likelihood methods. The results reveal five undescribed well-supported lineages. Four of the lineages represent new species described as Micarea pseudomicrococca Launis & Myllys sp. nov., M. czarnotae Launis, van den Boom, Sérusiaux & Myllys sp. nov., M. microareolata Launis, Pykälä & Myllys sp. nov. and M. laeta Launis & Myllys sp. nov. In addition, a fifth lineage was revealed that requires further study. Micarea pseudomicrococca is characterized by an olive green granular thallus, small cream-white or brownish apothecia lacking the Sedifolia-grey pigment and two types of paraphyses up to 2 µm wide. Micarea czarnotae forms a granular, densely granular or continuous olive green thallus, convex to hemispherical apothecia often with the Sedifolia-grey pigment and no crystalline granules in the thallus. Micarea microareolata is characterized by a ± pale green areolate thallus (composed of goniocysts), cream-white apothecia lacking the Sedifolia-grey pigment and narrow spores. Micarea laeta has a vivid to olive green granular thallus, pale apothecia lacking the Sedifolia-grey pigment and wider spores compared to M. microareolata. Descriptions, images and a key are provided for the new species. Crystalline granules are introduced as a novel species-level character for Micarea.