Bryophytes can be used as indicators of valuable pasture biotopes in

The sensitivity of bryophytes to grassland abandonment and to the consequent overgrowing by vascular plants (Aude & Ejrnæs 2005, Peintinger & Bergamini 2006) means that bryophytes may be especially useful as the indicators of grassland quality. The continuously grazed mesic semi-natural grasslands sustained more diverse bryophyte communities than the abandoned and the most of the restored sites in this study (I). The most valuable vascular plant communities are also found in the continuously grazed grasslands (Pykälä 2003). As bryophyte cover was also highest in these sites, the cover may potentially be used in the identification of those mesic semi-natural grasslands that host the most valuable bryophyte and vascular plant communities (I).

Instead, the diversity of many insect orders apparently peaks at the lower grazing intensities (e.g. Pöyry et al. 2004).

Species Abietinella abietina, Climacium dendroides and Syntrichia ruralis are potential species-level indicators for diverse

grassland plant communities on Finnish non-calcareous clay soils as their abundance was strongly inclined to the continuously grazed sites (I). These species are also easy to identify already in the field. During & Willems (2003) mention A.

abietina as a species that suffer from overgrowth and eutrophication in Dutch chalk grasslands. Among other species abundant in the continuously grazed sites, Rhytidiadelphus squarrosus is also known to thrive in very eutrophicated growing conditions (Ingerpuu et al. 1998) and it is thus less useful as an indicator.

The use of bryophytes as the indicators of valuable forest pasture biotopes is questionable. There were very few species characteristic of the traditionally managed forest pastures (III, IV). Furthermore, neither bryophyte richness nor cover correlated with the species richness of vascular plants in this study (IV). Near threatened (NT) Tayloria tenuis seems to be typical of at least North-Karelian forest pastures and its presence in a pasture may indicate a long continuity of grazing in that particular site. However, we do not know if its abundance correlates with any other factors except the continuous supply of dung patches. Beyond species level indicators, the abundance of acrocarpous bryophytes on bare mineral soil may indicate high ecological quality in this biotope.

Before further studies, however, the ecological quality only refers to the conditions for bryophytes.

3.3.4 Intensive forestry homogenize forest stand structures in forest pastures

Vainio et al. (2001) reported that the most of the Finnish forest pastures have considerably lost their ecological value because of intensive forestry. Forestry practices have decreased the variation in tree species composition, forest stand density and age-class structure typical of representative forest pastures (Vainio et al. 2001). The lack of dead wood is also a common problem (Vainio et al. 2001). As a consequence, intensive forestry is regarded as a major threat to wooded semi-natural rural biotopes in Finland (Schulman et al. 2008a,b). The

biodiversity effects of forest stand structure were not studied in more detail in this study, but the results and field observations indicate that this issue should receive more attention in the future.

High microhabitat heterogeneity or diversity (Shannon’s index) was related to high bryophyte species richness in the forest pastures (III), and forest stand structure is one factor that fundamentally affects the variation in microhabitat conditions.

Vascular plant vegetation, for example, differs between open and wooded parts of wooded meadows (Haeggström 1983). In general, vascular plant diversity increases with light availability in hemiboreal wooded meadows (Einarsson & Milberg 1999, Aavik et al. 2008) although contrasting results have locally been obtained (Skornik et al. 2008). In this study, bryophyte cover was lower near the edge of the grassland pastures than in the inner parts of the forest pastures (IV). Many bryophyte species prefer shaded and moist microhabitats (Moen & Jonsson 2003, Hylander 2005). These results indicate that high variation in forest stand structure may result in high overall plant diversity in forest pastures.

The internal heterogeneity of forest stand was, however, generally low in the forest pastures of this study. The number of tree species was practically the same in the forest pastures connected to grasslands (on average 2.8 species per site) and in the adjacent forests (on average 2.9 species per site). The age-class structures and stand densities also appeared very homogenous. In fact, the forest stand structures in the forest pastures resembled the ones in the forests managed for commercial purposes. Furthermore, large logs were very occasional (III). There were also a few sites with spruce as the dominant tree species and it is questionable whether these sites provide any forage for cattle or if their only function is to offer shelter and resting sites (Fig 6). An increase in the abundance of spruce is one of the ecological problems associated with the decrease in traditional-type management in Finnish forest pastures (Vainio 2001).

Figure 6. Homogenous forest stand structure and the dominance of spruce are two ecological problems in forest pastures. Kitee.

Even without and before further studies, it can be stated that more attention should be paid on forest stand structure in the management of forest pastures. The goal should be a structurally diverse forest stand consisting of both living and dead trees of various tree species (Fig 7). This would also result in a spatially more heterogeneous grazing pattern. It is unlikely that the increase in structural heterogeneity in forest pastures would harm any species group. Instead, positive effects on biodiversity are evident. The amount of structural heterogeneity and the availability of microhabitats (mineral soil patches, CWD and old deciduous trees in particular) may also be useful measures when evaluating the ecological value of forest pastures.

Figure 7. An example of a representative forest stand structure in a forest pasture. The lack of dead wood is still a problem also in this site.

Kitee.

3.3.5 Forest pastures may be more vulnerable to high grazing intensities than mesic grasslands

The risk of too high grazing intensity is another issue worth addressing in this thesis, even if it was only briefly touched in articles I-IV. By too high I mean intensities that decrease biodiversity to a remarkable degree. The risk of too low grazing intensity in mesic grasslands has been discussed in chapter 3.3.1.

The effects of cattle grazing on vascular plant diversity are usually positive in productive biotopes in northwestern Europe (Olff & Ritchie 1998, Proulx & Mazumder 1998). The positive effects are potentially attributable to the survival of many

vegetation (Pykälä 2004, Johansson et al. 2010) and the results of this study illustrate that bryophytes form one of these subordinate species groups benefitting from grazing (I, II).

The impacts of grazing on biodiversity are often scale-dependent (Bello et al. 2007, Giladi et al. 2011). In this study, species richness at gamma level presumably is the most suitable response variable when exploring the effects of grazing intensity on bryophyte and vascular plant diversity. This variable depicts species richness at the level of grassland/pasture and it was used in all of the articles I-IV.

In the mesic semi-natural grasslands, the positive relationship between bryophyte species richness (gamma) and grazing intensity was evident even in the highest intensities (II).

Pykälä (2003) did not record any adverse effects of high grazing intensities on vascular plant diversity in this biotope, either. The cover of bare soil was selected to measure grazing intensity (trampling effect to be precise) in the forest pastures (IV). It turned out that the species richness of neither bryophytes nor vascular plants decreased even in very high covers of bare soil.

This was somewhat surprising as the cover of bare soil was very high in a few sites (the range of mean 0–49.5 %) and generally much higher than in the mesic grasslands (the range of mean 0.01–0.02 %). Müller et. al (2014) found that the cover of bare soil exceeding 12 % decreased bryophyte diversity in a grassland environment in Germany.

In conclusion, grazing intensities that threaten plant diversity are apparently rare in mesic grasslands on clay soils. Instead, forest pastures may be more vulnerable to high intensities and this issue should be kept in mind in the management of this biotope.

4 Concluding remarks

This study demonstrates that bryophytes form an integral part of biodiversity in mesic semi-natural grasslands and forest pastures. Undoubtedly, this is the case in the other semi-natural rural biotopes as well, but there is a lot of work before we have a comprehensive picture of bryophyte communities in all of these environments. Wet coastal grasslands, currently very rare grazed fens, wooded pastures in the hemiboreal vegetation zone and dry grasslands on mesotrophic and calcareous soils would be good scenes for future studies.

Based on the results, bryophytes should be taken into account in the management of mesic semi-natural grasslands and forest pastures. One relevant reason to enhance bryophyte diversity in these two biotopes by restoration and proper management is that the measures beneficial to bryophytes seem to benefit many other species groups as well. The most severe conflict is expected between the high grazing intensity required by bryophytes and the low intensity required by some insect groups. This highlights the need for spatially varying grazing intensities and management practises at landscape level. We also need more studies that genuinely compare the effects of management and restoration on different species groups.

The major importance of soil disturbances to bryophyte diversity in the mesic semi-natural grasslands and forest pastures was evidently one of the main results of this thesis. It would be interesting to examine the role of soil disturbances also in a larger scale, beyond the borders of semi-natural rural biotopes. Bryophytes on bare mineral soil should also be studied at different times of the year, as midsummer is not necessarily the most favourable moment to find many short-lived species.

This study was concentrated on cattle grazing. Although cow seems to be very suitable species for the management of semi-natural rural biotopes, further studies should also focus on the

effects of other potential grazers. This is important not only because of the divergent effects of different grazer species but also because “recreational” species, such as horse and pony, and even exotic species in Finnish context, such as bison and alpaca, may have potential to counteract the decrease in traditional animal husbandry in Finland.

In this thesis, I have presented various ideas and recommendations of the management practices that would benefit bryophytes and increase biodiversity in the semi-natural rural biotopes. However, the real challenge is how to keep the management of these biotopes alive in the modern world, where economic reasoning rules the decision making of both individuals and societies. The management of semi-natural rural biotopes is rarely profitable in free markets nowadays. While the management is of low intensity in terms of chemical inputs, it usually demands lots of expensive labour (Bignal &

McCracken 1996). Natural sciences can only point out the ecological importance of these biotopes. At present, subsidies form the main mechanism by which the management is tried to keep alive in Finland. Subsidies are, however, prone to ever changing political climate and we urgently need other ways to make the management of semi-natural rural biotopes a real alternative (economically, socially and culturally) for different landowners, even for those who do not have a former experience of the management.

5 References

Aartolahti T (1975) The morphology and development of the river valleys in southwestern Finland. Annales Academiae Scientiarum Fennicae A 116: 1-75.

Aavik T, Jogar U, Liira J, Tulva I & Zobel M (2008) Plant

diversity in a calcareous wooded meadow – the significance of management continuity. Journal of Vegetation Science 19:

475-484.

Aavik T, Holderegger R, Edwards P J & Billeter R (2013) Patterns of contemporary gene flow suggest low functional connectivity of grasslands in a fragmented agricultural landscape. Journal of Applied Ecology 50: 395-403.

Aude E & Ejrnæs R (2005) Bryophyte colonization in

experimental microcosms: the role of nutrients, defoliation and vascular vegetation. Oikos 109: 323-330.

Auestad I, Rydgren K & Austad I (2011) Road verges: potential refuges for declining grassland species despite remnant vegetation dynamics. Annales Botanici Fennici 48: 289-303.

Austrheim G, Gunilla E, Olsson A & Grontvedt E (1999) Land-use impact on plant communities in semi-natural sub-alpine grasslands of Budalen, central Norway. Biological Conservation 87: 369-379.

Bakker J P, Elzinga J A & de Vries Y (2002) Effects of long-term cutting in a grassland system: perspectives for restoration of plant communities on nutrient-poor soils. Applied Vegetation Science 5: 107-120.

Bakker J P, Rosen E, Ozinga W A, Bretfeld M, Feldt T & Stahl J (2012) Long-term effects of scrub clearance and litter removal on the re-establishment of dry alvar grassland species.

Annales Botanici Fennici 49: 21-30.

Bello F, Lepš J & Sebastia M-T (2007) Grazing effects on the species-area relationship: variation along a climatic gradient in NE Spain. Journal of Vegetation Science 18: 25-34.

Berg A, Gärdenfors U, Hallingbäck T & Noren M (2002) Habitat preferences of red-listed fungi and bryophytes in woodland key habitats in southern Sweden - analyses of data from a national survey. Biodiversity and Conservation 11: 1479-1503.

Bergamini A, Peintinger M, Schmid B, Urmi E (2001) Effects of management and altitude on bryophyte diversity and composition in montane calcareous fens. Flora 196: 180-193.

Bergmeier E, Petermann J & Schroder E (2010) Geobotanical survey of wood-pasture habitats in Europe: diversity, threats and conservation. Biodiversity and Conservation 19: 2995-3014.

Bignal E M & McCracken D I (1996) Low-intensity farming systems in the conservation of the countryside. Journal of Applied Ecology 33: 413-424.

Bobbink R & Willems J (1993) Restoration management of abandoned chalk grassland in the Netherlands. Biodiversity and Conservation 2: 616-626.

Bobbink R, Hicks K, Galloway J, Spranger T, Alkemade R, Ashmore M, Bustamante M, Cinderby S, Davidson E, Dentener F, Emmet B, Erisman J W, Fenn M, Gilliam F, Nordin A, Pardo L & De Vries W (2010) Global assessment of nitrogen deposition effects on terrestrial plant diversity: a synthesis. Ecological Applications 20: 30-59.

Ceulemans T, Merckx R, Hens M & Honnay O (2013) Plant species loss from European semi-natural grasslands following nutrient enrichment - is it nitrogen or is it

phosphorus? Global Ecology and Biogeography Letters 22: 73-82.

Chapman S B & Rose R J (1991) Changes in the vegetation at Coom Rigg Moss National Nature Reserve within the period 1958-86. Journal of Applied Ecology 28: 140-153.

Cole H A, Newmaster S G, Bell F W, Pitt D & Stinson A (2008) Influence of microhabitat on bryophyte diversity in Ontario

mixedwood boreal forest. Canadian Journal of Forest Research 38: 1867-1876.

Concostrina-Zubiri L, Huber-Sannwald E, Martinez I, Flores J L F & Escudero A (2013) Biological soil crusts greatly

contribute to small-scale soil heterogeneity along a grazing gradient. Soil Biology & Biochemistry 64: 28-36.

Crawley M J, Johnston A E, Silvertown J, Dodd M, de Mazancourt C, Heard M S, Henman D F & Edwards G R (2005) Determinants of species richness in the park grass experiment. American Naturalist 165: 179-192.

Cunha A, Power S A, Ashmore M R, Green P R S, Haworth B J &

Bobbink R (2002) Whole ecosystem nitrogen manipulation:

an updated review. JNCC Report No 331.

Dufrêne M & Legendre P (1997) Species assemblages and indicator species: the need for a flexible asymmetrical approach. Ecological Monographs 67: 345-366.

During H J (1992) Ecological classifications of bryophytes and lichens. In Bates J W & Farmer A M (Eds) Bryophytes and lichens in a changing environment. Oxford University Press, Oxford, pp. 1-31.

During H J & Willems J H (1986) The impoverishment of the bryophyte and lichen flora of the Dutch grasslands in the thirty years 1953-1983. Biological Conservation 36: 143-158.

Dynesius M & Hylander K (2007) Resilience of bryophyte communities to clear-cutting of boreal streamside forests.

Biological Conservation 135: 423-434.

Dynesius M, Hylander K, Nilsson C (2009) High resilience of bryophyte assemblages in streamside compared to upland forests. Ecology 90: 1042-1054.

Edmondson J, Terribile E, Carroll J A, Price E A C & Caporn S I M (2013) The legacy of nitrogen pollution in heather

moorlands: Ecosystem response to simulated decline in nitrogen deposition over seven years. Science of Total Environment 44: 138-144.

Einarsson A & Milberg P (1999) Species richness and distribution in relation to light in wooded meadows and pastures in southern Sweden. Annales Botanici Fennici 36: 99-107.

Ellenberg H, Weber H E, Dull R, Wirth V, Werner W &

Paulissen D (1991) Zeigerwerte von Planzen in Mitteleuropa.

Scripta Geobotanica 18: 1-248.

Essl F, Steinbauer Klaus, Dullinger S, Mang T & Moser D (2014) Little, but increasing evidence of impacts by alien

bryophytes. Biological Invasions 16: 1175-1184.

European commission (2009) Report from the commission to the council and the European parliament. Composite report on the conservation status of habitat types and species as required under article 17 of the habitats directive. KOM (2009) 358 final.

Geiger F, Bengtsson J, Berendse F, Weisser W W, Emmerson M, Morales M B, Ceryngier P, Liira J, Tscharntke T, Winqvist C, Eggers S, Bommarco R, Part T, Bretagnolle V, Plantegenest M, Clement LW, Dennis C, Palmer C, Onate J J, Guerrero I, Hawro V, Aavik T, Thies C, Flohre A, Hanke S, Fischer C, Goedhart P W & Inchausti P (2010) Persistent negative effects of pesticides on biodiversity and biological control potential on European farmland. Basic and Applied Ecology 11: 97-105.

Giladi I, Ziv Y & May F (2011) Scale-dependent determinants of plant species richness in a semi-arid fragmented

agro-ecosystem. Journal of Vegetation Science 22: 983-996.

Grime J P (2001) Plant strategies, vegetation processes and ecosystem properties. John Wiley & Sons Ltd, Chichester.

Güsewell S, Buttler A & Klotzli F (1998) Short-term and long-term effects of mowing on the vegetation of two calcareous fens. Journal of Vegetation Science 9: 861-872.

Haeggström C-A (1983) Vegetation and soil of the wooded meadows in Nåtö, Åland. Acta Botanica Fennica 120: 1-66.

Haeggström C-A (1990) The influence of sheep and cattle grazing on wooded meadows in Aland, SW Finland. Acta Botanica Fennica 141: 1-28.

Habel J C, Dengler J, Janisova M, Török P, Wellstein C & Wiezik M (2013) European grassland ecosystems: threatened

hotspots of biodiversity. Biodiversity and Conservation 22:

2131-2138.

Hejcman M, Száková J, Schellberg J, Šrek P, Tlustoš P & Balík J (2010) The Rengen Grassland experiment: bryophytes biomass and element concentrations after 65 years of fertilizer application. Environmental Monitoring and Assessment 166: 653-662.

Hellström K, Huhta A-P, Rautio P, Tuomi J, Oksanen J & Kari L (2003) Use of sheep grazing in the restoration of semi-natural meadows in northern Finland. Applied Vegetation Science 6: 45-52.

Hellström K, Huhta A-P, Rautio P & Tuomi J (2006) Search for optimal mowing regime - slow community change in a restoration trial in northern Finland. Annales Botanici Fennici 43: 338-348.

Hellström K, Huhta A-P, Rautio P & Tuomi J (2009) Seed introduction and gap creation facilitate restoration of meadow species richness. Journal for Nature Conservation 4:

236-244.

Hoste-Danyłow A, Romanowski J & Zmihorski M (2010) Effects of management on invertebrates and birds in extensively used grassland of Poland. Agriculture, Ecosystems and Environment 139: 129-133.

Huhta A P, Rautio P, Tuomi J & Laine K (2001) Restorative mowing on an abandoned semi-natural meadow: Short-term and predicted long-term effects. Journal of Vegetation Science 12: 677-686.

Hutsemekers V, Dopagne C & Vanderpoorten A (2008) How far and how fast do bryophytes travel at the landscape scale?

Diversity and Distributions 14: 483-492.

Hylander K (2005) Aspect modifies the magnitude of edge effects on bryophyte growth in boreal forests. Journal of Applied Ecology 42: 518-525.

Hylander K & Johnson S (2010) In situ survival of forest

bryophytes in small-scale refugia after an intense forest fire.

Journal of Vegetation Science 21: 1099-1109.

Ingerpuu N, Kull K & Vellak K (1998) Bryophyte vegetation in a wooded meadow: relationships with phanerogam diversity and responses to fertilization. Plant Ecology 134: 163-171.

Janssens F, Peeters A, Tallowin J R B, Bakker J P, Bekker R M, Fillat F & Oomes M J M (1998) Relationship between soil chemical factors and grassland diversity. Plant and Soil 20: 69-78.

Johansson V A, Cousins S A O & Eriksson O (2010) Remnant populations and plant functional traits in abandoned semi-natural grasslands. Folia Geobotanica 46: 165–179.

Jonsson B G & Esseen P A (1990) Treefall disturbance maintains high bryophyte diversity in a boreal spruce forest. Journal of Ecology 78: 924-936.

Jonsson B G & Esseen P A (1998) Plant colonization in small forest-floor patches: importance of plant group and disturbance traits. Ecography 21: 518-526.

Kalliola R (1973) Suomen kasvimaantiede [The vegetation geography of Finland]. WSOY, Porvoo. (In Finnish)

Keizer P J, Van Tooren B F & During H J (1985) Effects of bryophytes on seedling emergence and establishment of short-lived forbs in chalk grassland. Journal of Ecology 73: 493-504.

Kruess A & Tscharntke T (2002) Contrasting responses of plant and insect diversity to variation in grazing intensity.

Biological Conservation 106: 293-302.

Kontula T, Lehtomaa L, Pykälä J (2000) Land-use history, vegetation and flora in Rekijoki valley, Somero, SW Finland.

Suomen ympäristö [The Finnish Environment] 306: 1-91. (in Finnish with an English summary)

Kotiluoto R (1998) Vegetation changes in restored seminatural meadows in the Turku Archipelago of SW Finland. Plant Ecology 136: 53-67.

Kull O, Aan A & Soelsepp T (1995) Light interception, nitrogen and leaf mass distribution in a multilayer plant community.

Functional Ecology 9: 589-595.

Laaka-Lindberg S, Anttila S & Syrjänen K (2009) Suomen uhanalaiset sammalet [Threatened Bryophytes of Finland].

Vammalan kirjapaino Oy, Sastamala.

Lampimäki T (1939) Nautakarjan laiduntamisesta metsämailla.

Silva Fennica 50: 1-106.

Luoto M, Rekolainen S, Aakkula J & Pykala J (2003) Loss of plant species richness and habitat connectivity in grasslands associated with agricultural change in Finland. Ambio 32: 447-452.

Löbel S, Dengler J & Hobohm C (2006) Species richness of vascular plants, bryophytes and lichens in dry grasslands: the

Löbel S, Dengler J & Hobohm C (2006) Species richness of vascular plants, bryophytes and lichens in dry grasslands: the

In document Bryophytes in semi-natural rural biotopes (sivua 53-78)