Dispersal of Bryophytes Across Landscapes

Dispersal of bryophytes across landscapes

Niklas Lönnell ©Niklas Lönnell, Stockholm University 2014 Front cover illustration: Niklas Lönnell Back cover photograph: Carita Lönnell Paper cover: 270g Scandia 2000 Paper insert: 100g Color copy naturalwhite

ISBN 978-91-7447-778-8

Printed in Sweden by US-AB, Stockholm 2014 Distributor: Department of Ecology, Environment and Plant Sciences, Stockholm University

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Contents

Glossary ...... 6

Abstract ...... 7

List of Papers ...... 9

Introduction ...... 10 Dispersal ...... 10 Bryophyte dispersal ...... 13

Objectives of the thesis ...... 16

Methods ...... 17 Study areas ...... 18 Study system 1 – Dicelium nudum ...... 18 Study species ...... 18 Study system 2 – limed mires ...... 21

Results and discussion ...... 23

References ...... 28

Svensk sammanfattning ...... 33

Tack ...... 36

Glossary Anemochory – Wind dispersal Antheridium – The male elliptical reproductive organ from where the spermatozoids have to swim to the archegonium. Archegonium – The female bottle-shaped reproductive organ with a long neck with a canal which lead down to the venter where the eggcell is situated. Bryophytes – A generic term for the polyphyletic group consisting of mosses, liverworts and hornworts Deposition (syn. landing) – The final stage of dispersal where the diaspores come to rest Diaspore (syn. propagule) – A dispersal unit that could be a seed, spore, gemmae or even a fragment (as bryophytes can regenerate from any part of the gametophyte). Dispersal – Transportation of diaspores away from the plant of origin (See introduction) Impaction – A deposition process when a diaspore continues its path towards an object instead of following the air stream around it Interception – A deposition process when a diaspore travels so near an object that it touches it Lagrangian stochastic dispersion model – A model that simulates a large number of trajectories of a single diaspore taking into account the variation in wind components. Liming – A practice to spread calcium compounds (to increase the pH) Release (syn. abscission, take-off) – The process when the diaspores leave the place of origin, in the case of bryophyte spores the capsule. Sedimentation – A deposition process when a diaspore is deposited due to gravity Settling velocity/speed (syn. falling/fall velocity/speed, terminal velocity/speed) – A measure of how fast a diaspore falls. It is defined as the diaspore speed when the drag force (upwards) and the force by gravity (down- wards) are equal and the particle will not increase its speed. Vector (syn. agent) – A carrier of diaspores, e.g. wind, water and animals -chory – a suffix used to describe different types of dispersal, for example wind dispersal would be anemochory -phily – a suffix used to describe different types of pollen dispersal, but could also be used to describe spore dispersal, wind dispersal would be an- emophily

0:6 Doctoral dissertation Abstract Niklas Lönnell Department of Ecology, Envi- ronment and Plant Sciences Stockholm University Lilla Frescati SE-106 91 Stockholm Sweden

Dispersal, especially long-distance dispersal, is an important component in many disciplines within biology. Many species are passively dispersed by wind, not least spore-dispersed organisms. In this thesis I investigated the dispersal capacity of bryophytes by studying the colonization patterns from local scales (100 m) to landscape scales (20 km). The dispersal distances were measured from a known source (up to 600 m away) or inferred from a connectivity measure (1–20 km). I introduced acidic clay to measure the colonization rates over one season of a pioneer moss, Discelium nudum (I–III). I also investigated which vascular plants and bryophytes that had colonized limed mires approximately 20–30 years after the first disturbance (IV). Discelium effectively colonized new disturbed substrates over one season. Most spores were deposited up to 50 meters from a source but the relationship between local colonization rates and connectivity increased with distance up to 20 km (I–III). Also calcicolous wetland bryophyte species were good colonizers over similar distances, while vascular plants in the same environment colonized less frequently. Common bryophytes that produce spores frequently were more effective colonizers, while no effect of spore size was detected (IV). A mechanistic model that take into account meteorological parameters to simulate the trajectories for spores of Discelium nudum fitted rather well to the observed colonization pattern, especially if spore release thresholds in wind variation and humidity were accounted for (III). This thesis conclude that bryophytes in open habitats can disperse effectively across landscapes given that the regional spore source is large enough (i.e. are common in the region and produce spores abun- dantly). For spore-dispersed organisms in open landscapes I suggest that it is often the colonization phase and not the transport that is the main bottle-neck for maintaining populations across landscapes.

Keywords: anemochory, bryophytes, colonization, connectivity, diaspores, dispersal kernel, establishment, spore dispersal, long-distance dispersal, mechanistic model, mosses, realized dispersal, spore release, Lagrangian stochastic model, wind dispersal

0:7

0:8 List of Papers

This thesis is based on the work contained in the following papers, referred to by Roman numerals in the text

I. Lönnell, N., Hylander, K., Jonsson, B.G. & Sundberg, S. (2012) The fate of the missing spores — patterns of realized dispersal beyond the closest vicinity of a sporulating moss. PLoS ONE, 7, e41987.

II. Lönnell, N., Jonsson, B.G. & Hylander, K. Production of diaspores at the landscape level regulates local colonization: an experiment with a spore-dispersed moss. Accepted for publication in Ecography. DOI: 10.1111/j.1600-0587.2013.00530.x

III. Lönnell, N., Sundberg, S., Norros, V., Rannik, Ü., Johansson, V., Ovaskainen, O. & Hylander, K. Colonization patterns of a wind-dispersed moss in relation to modelled dispersal based on meteorological data. Manuscript

IV. Lönnell, N. & Hylander, K. Calcicolous plants colonize limed mires after long-distance dispersal. Manuscript

0:9 Introduction

Dispersal Dispersal in a biological context can be defined as "intergenerational movement" or "movement leading to gene flow" or "movement of individuals to new locations away from their parents" and as it is important component in many different both theoretical and applied disciplines it has rendered an increasing attention during the last decades (Bullock, Kenward & Hails 2002; Cousens, Dytham & Law 2008; Clobert et al. 2012).

Dispersal can be active, where the individual animal itself can decide on the direction, length and final goal of the dispersal event, or passive,where the individual or dispersal unit (diaspore) is transported by some other vector e.g. animals (zoochory), water (hydrochory) or wind (anemochory) (Pijl 1982). Many fields of ecology and conservation biology are dominated by research concerning animals, which is reflected in the high number of studies that have been devoted to active dispersal and animal-mediated pollination and dispersal. A ten- dancy for such a bias towards viewing dispersal from an animal perspective could be detected in the conceptual framework of movement of an individual, where four mechanistic components that influences a movement path are distinguished: internal state (why move?), motion capacity (how to move?), navigation capacity (when and where to move?) and external factors (Nathan et al. 2008a). Consequently, an attempt to apply it on a wind-dispersed fungi encountered some chal- lenges: for example to distinguish between navigation and motion capacity is not unambiguous and the internal state of both the mother plant and the diaspores could be affected independently by external factors (Norros 2013).

Wind disperses a plethora of organisms: for example vascular plants (pollen and seeds), bryophytes, lichens, fungi, bacteria, and protozoan. Also some larger animals rely on passive wind dispersal, for example spiders that fly with help of strands of silk (Bonte 2012). That wind could be an efficient vector is indicated by the fact that the strategy to have very small seeds (so called dust seeds) have evolved several

0:10 times among flowering plants (Eriksson & Kainulainen 2011). Wind is also an important vector for passive long-distance dispersal of species which otherwise has active short-distance dispersal (e.g. insects) (Compton 2002; Sturtevant et al. 2013). A majority of wind-dispersed diaspores will end up in an environment where they cannot survive and establish. One extreme example is all pine pollen that miss the very small surface of a stigma and can be seen colouring the ground and water surfaces yellow in May-June. For all wind-dispersed species is the number of produced spores (the source strength) accordingly an important factor. The source strength is influenced by the number of individuals, how often they reproduce and how many diaspores that are produced per individual (Fig. 1).

Figure 1. The different phases related to dispersal. Release, transport and deposition are the phases traditionally included in dispersal. If establishment is included the term realized dispersal could be used. The arrows represent the filters that could influence which species from the regional species pool that you find in a local community according to Morin (1999). (Morin 1999). .

0:11 Release conditions and diaspore characteristics are two ways that plants can influence the dispersal distance of a single diaspore and could be classified into the component navigation capacity in the movement ecology paradigm (Nathan et al. 2008a; Norros 2013). Be- sides seasonal variation in the production of diaspores there seem to be diurnal variations in production and/or release of diaspores judged from measurements of spore concentration in the air, for many fungi at least (Pady, Kramer & Clary 1967; Gregory 1973). One mechanism that could facilitate long-distance dispersal is release triggered by some environmental conditions such as high wind speeds. Such non- random release has been suggested for an increasing number of species (vascular plants, fungi and bryophytes) (Johansson et al.; Aylor 1990; Greene 2005; Skarpaas, Auhl & Shea 2006; Jongejans et al. 2007; Borger et al. 2012). Some spore-dispersed organisms, e.g. peat mosses Sphagnum spp. and some fungi, have a violent discharge of their spores (Sundberg 2002; Roper et al. 2010; Whitaker & Edwards 2010), which is still another mechanism that could enhance the probability of being transported further away.

The settling velocity, a measure how fast a diaspore falls and will reach the ground, is one important property to know in order to predict how long horizontal distance a diaspore will be transported under a given wind speed. The heavier a diaspore is the faster it will reach the ground, given that the species not has any adaptations to increase the buoancy such as plumes on its seeds or air sacs on its pollen. For a spherical diaspore with the same density the diameter could be used as a good proxy of settling velocity (and thus transport capacity). Many fungal spores are ellipsoid and ca 10 μm long (Weber & Hess 1976), the spherical spores of mosses and liverworts have a diameter of 10– 50 (-200) μm (Hill et al. 2007), the majority of ferns have a diameter of 20–60 μm (Tryon 1970) and orchids have elongated seeds from 0.1 mm to 4 mm long, but more commonly around 1 mm (Bojnansky & Fargasova 2007), while most wind-dispersed pollen have a diameter of 20–60 μm (Faegri & Pijl 1979).

Differences in diaspore survival after desiccation, UV-radiation and freezing have been reported and could influence a species ability for a successful long-distance dispersal (Zanten 1978; Zanten & Gradstein 1988; Wiklund & Rydin 2004; Löbel & Rydin 2010; Norros 2013).

One critical stage in the transport of diaspores is for them to reach above the canopy where the wind speeds are higher and it is easier to be swept away to higher altitudes and longer horizontal distances. An- other mechanism is for diaspores to be lifted with warm air, so called

0:12 thermal upheaval, that could be effective in many cases (Tackenberg, Poschlod & Kahmen 2003).

Deposition occurs through several mechanisms, whose relative importance varies with the size of the diaspore, properties of the collect- ing elements (e.g. a pine needle or a leaf) and the flow conditions. Interception (when a diaspore travels so near an object that it touches it), impaction (when a diaspore continues its path towards an object instead of following the air stream around it) and sedimentation (when a diaspore is deposited due to gravity) are the mechanisms that mainly are affecting particles above 2 μm (note that turbulent impaction or turbophoresis is also a mechanism of importance, but in general there is not very good consensus about the importance of this mechanism (Üllar Rannik pers. comm.). Interception is important for diaspores 2– 10 μm but influences also larger diaspores, while impaction is the dominant deposition mechanism for diaspores 10–100 μm in conifer- ous forest (Petroff et al. 2008). Impaction increases with increasing wind speed, increasing diaspore size (mass) and decreasing diameter of the object and the stickiness of the surface of the object (Gregory 1973). Sedimentation is especially important under still conditions with wind speeds below 2 m s-1 and for heavy diaspores.

Finally if a viable spore arrives at a habitat the establishment phase could be limited by abiotic factors such as pH, phosphorous, moisture (Sundberg & Rydin 2002; Wiklund & Rydin 2004; Löbel & Rydin 2010) or by biotic factors such as competition or absence of a symbi- ont.

Bryophyte dispersal

Besides by spores, bryophytes disperse with gametophyte fragments as well as a wide array of specialized asexual diaspores: gemmae, tu- bers, bulbils, fragile braches and leaves (Laaka-Lindberg, Korpelainen & Pohjamo 2003). These are often larger than the spores but have a higher germination rate and their production are less costly and could begin in earlier life stages, at least in epiphytes (Löbel & Rydin 2009, 2010). However, as spores are smaller than most asexual diaspores they are generally thought to have a higher probability of long- distance dispersal.

The only well documented specialized dispersal with animals as vec- tors that can be found among the mosses is in the family Splachnaceae

0:13 where both visual (broad hypophysis) and olfactory (odours that imi- tate the smell of dung) ques are used to lure the animal vector to land on the sporophyte (Koponen 1990; Marino, Raguso & Goffinet 2009). Flies then transport the spores to new suitable substrates e.g. in the form of fresh dung. Unspecialized bryophyte dispersal with other animals has been suggested (Glime 2007) and from a long-distance dispersal perspective the speculations about possibilities of bird mediated dispersal are the most interesting. Otherwise the main vector for long- distance dispersal of most bryophyte spores is wind.

Bryophyte spore size 300 200 Frequency 100 0

0 50 100 150 200

Spore size (micrometre)

Figure 2. A histogram over the average spore size (µm) for 1035 mosses and liverworts in Great Britain (Hill et al. 2007). The vertical line marks the spore size of Discelium nudum (25 µm). Most species with spores above 50 μm are liverworts while the outlier with spores around 200 μm is the acrocarpous moss Archidium alternifolium.

0:14 Most bryophyte spores are spherical and 10–50 μm in diameter even if there are some exceptions with spores up to 100–200 μm in the British bryophyte flora (Hill et al. 2007) (Fig. 2).

Sexual reproduction (i.e. spore production) occur in most bryophyte species. However, there are species that not has been found with capsules. The sporophyte production not only vary among species, but also abiotic factors, such as frost and precipitation during the development of the sporophyte, could influence the final spore output (Sundberg 2002; Ruete, Wiklund & Snäll 2012). The number of spores produced per capsule varies with capsule size and size of the diaspores and can vary even within species (Sundberg & Rydin 1998). The interspecific differences are large and range from 1.4–9 Million spores in Buxbaumia viridis (Wiklund 2002) to as few as 16 in Archidium alternifolium (Miles & Longton 1992a) (Fig. 3).

Figure 3. The spore output per capsule versus spore size plotted in a log-log-space for 92 species for which data were available (Ingold 1959; Schuster 1966; Kreulen 1972; Ingold 1974; Longton 1976; Mogensen 1978; Söderström & Jonsson 1989; Miles & Longton 1992; Boros et al. 1993; Sundberg & Rydin 1998; Wiklund 2002; He & Zhu 2010; Cuming 2011). Some genera are overrepresented e.g. Riccia and Sphagnum. The figure has been modified from Lönnell (2011). Discelium nudum is marked by a cross, even if it belongs to the group acrocarpous mosses.

(Ingold 1959, 1974; Schuster 1966; Kreulen 1972; Longton 1976; Mogensen 1978; Söderström & Jonsson 1989; Miles & Longton 1992a; Boros et al. 1993; Sundberg & Rydin 1998; Wiklund 2002; He & Zhu 2010; Cuming 2011; Lönnell et al. 2012)

0:15 Objectives of the thesis

The main objective of this thesis was to study spore dispersal of bryophytes by an experimental approach to help to remedy the lack of em- pirical evidence within this field. Moreover, we wanted to quantify the dispersal over scales (temporal and spatial) that could be relevant for a species to persist in a landscape. The specific objectives for the single studies were…

To experimentally quantify dispersal beyond those few meters that most studies have used and describe a dispersal kernel up to 600 m from a spore source. (I)

To assess the influence of the landscape connectivity on the colonization ability over one season for our study species (Discelium nudum) in a region where it is naturally occurring. (II)

To investigate to what extent a mechanistic model based on a number of measured meteorological parameters could predict the colonization pattern of the study species up to 100 m from a spore source and assess if incorporating realistic release threshold could improve the fit. (III)

To quantify on what spatial scale connectivity influence the colonization of calcicolous vascular plants and bryophytes in limed mires and to test if some traits (regional frequency, how often they reproduce and diaspore size) have an effect on which species and how often such species colonize the mires. (IV)

0:16 Methods

The two study system used in this thesis were the Discelium nudum- system where we studied colonizations on translocated clay over one season (I–III) and the limed mire system were we studied colonization

Figure 4. A).The 52 analysed limed mires in study IV B) The location for the study sites in study I (filled circle), study II (triangles) and study III (square).

0:17 of calcicolous species 20–30 years after the first liming event (IV).

Study areas The studies were all performed on mires in the boreal zone in Sweden: (I) A raised bog in the county of Gästrikland (N60.311°×E16.941°), (II) Sphagnum-dominated mires around Umeå (N63°–64°×E19°–20°), (III) a raised bog in Uppland (N60.045×E17.328) and (IV) limed mires in the middle part of Sweden (N59.395°×E12.080°– N65.1900°×E20.848°) (Fig. 4).

Study system 1 – Dicelium nudum Acidic clay was retrieved with an excavator from some meters depth. We then translocated it onto mires in pots (I, III) or heaps (II) as spore traps for the moss Discelium nudum. The reason for performing the studies on mires was primarily that the clay should be moist to secure good colonization conditions for our study species. Moreover, a mire is not a suitable habitat for the species (besides the introduced clay patches), which facilitates to control the spore sources. In two studies a spore source were translocated to a central point and pots where placed in four directions at distances up to 600 m (I) or in eight direction at distances up to 100 (III). The colonizations were then recorded during the autumn either in the field (I, II) or in the greenhouse (III).

Study species

Flag moss Discelium nudum (Dicks.) Brid is an acrocarpous moss, i.e. the spore capsule grows from the top of the shoot. When a moss spore germinates filamentous threads that look like a green alga develop; called protonema. Unlike many other moss species this stage is very conspicuous and long-lived in Discelium and can cover several square centimetres. However, adjacent protonemata grow into each other and the delimitation of one individual is not feasible. From one protonema several moss shoots are eventually formed. These are on the other hand very tiny (ca. 2 mm high) and only consist of a few leaves. The male shoots can readily be distinguished like orange dots on the green protonema mat, since the orange antheridia are not entirely covered by the surrounding leaves, while the female shoots are more inconspicu- ous. Discelium is said to be pseudo-dioecious, i.e. there are female and male shoots, but they come from the same protonema and hence spore

0:18 (Nyholm 1989). From the female shoot and a fertilized archegonium the sporophyte develops. The capsule is usually horizontally orien- tated 0.7–1.0 × 0.5–0.8 mm situated on a 1–3 cm seta (I) and the mouth of the capsule have a double peristome (Shaw & Allen 1985). The spores are spheroid with a diameter of 25 (21.8–30.1) mm (Boros et al. 1993) and in one capsule there are 15 000 ±2500 [SE] spores (I).

Its life cycle is completed within one year. The spore release occurs during a few weeks in April–May. The exact timing is dependent on the weather conditions during the spring, such as the duration of the snow cover and temperature and hence varies between years and lati- tudes. The fertilization occurs in summer and is vividly described by Hampus Wilhelm Arnell (Arnell 1875). The sporophytes develop dur-

Figure 5. The life cycle of flag moss Discelium nudum. The colonizations emanating from spore dispersal in April–May were recorded during the autumn when gametophyte shoots (male shoot the lower picture) and/or young sporophytes (the left picture) could be found. The growth of the protonema (right picture) could be detected already after a few weeks. The upper picture depicts a capsule from above with the reddish peristome at the capsule mouth.

0:19 ing autumn and mature during spring after the snow has melted away.

På ex, från Ångml. Hernosand 11 Juli 72 iakttogs en befruktningsakt. Några han- och honplantor voro preparerade i vatten för mikroskopet. Preparatet hvimlade av svärmande antherozoider. Ett arkegon, som, då det först kom inom synfältet, var slutet, men visade en tydlig kanal, öppnade sig, under det förf. betraktade detsamma. Alla antherozoider inom synhåll syntes i detsamma dragas till arkegoniets mynning; derefter drogo de sig så småningom ned genom kanalen, tills de kommo till centralblåsan. Denna försattes af antherozoiderna i en starkt vaggande rörelse, tills de slutligen upphörde att svärma och började att absorberas af centralblåsan, hvilken derigenom fick ett papillöst utseende ifrån att förut hafva haft en jemn yta.

Arnell, H.W. (1875)

The quotation translated and interpreted into a modernized version:

On a specimen from Härnösand in the county of Ångermanland 11 July 1872 was a fertilization observed. Some male and female plants were pre- pared in water for the light microscope. The preparation was filled with swarming spermatozoids. An archegonium, which was closed but showed an obvious canal as it came into view, opened in front of the eyes of the author. All the spermatozoids within view were attracted to the mouth and dragged themselves down through the canal until they reached the eggcell. It was by the spermatozoids put into a swinging motion until they stopped to swarm and started to be absorbed by the eggcell, which then got a papillose appearance; before this it had a smooth surface.

The species is found in Europe, North America and Asia in the northern hemisphere (Nyholm 1989). In Sweden the main distribution is on clay in the lower parts of the river valleys in the northern part of the country, but have scattered occurrences also in the southern part of the country. On a national scale it is rare, but can locally be rather abundant in its core area.

The substrate consists of clay or silt. It seems to be more abundant on glacial clay (which in the area often have a greyish colour) than on silt. The clay is often rather acidic: pH 4–5 (measured in CaCl2, which is thought to better reflect the pH for organisms under field conditions) or pH 5–6 (measured in deionized water) based on clay samples from a number of sites with Discelium (unpublished data). Preliminary results from a pilot study of germination gave also indications of a preference for acidic clay. I observed almost no establishment on clay with pH 8 (measured in deionized water) and intermediate establishment on clay with pH 6 (measured in deionized water) compared to a fast and prolific establishment on clay with pH 4.5 (measured in de-

0:20 ionized water) (unpublished data). The species is dependent on disturbance as it will be overgrown by other bryophytes or vascular plants within a few years without a renewed disturbance. Oddly enough it is very rare in arable fields where I only have spotted it a few times and then often in the margin of the field. More frequently it is found in ditches and road verges, in tracks in clear cuts and along watercourses.

Discelium was chosen as model organism for studying dispersal for the following reasons: 1) It is substrate specific, which is an advantage when it comes to spotting potential habitats in the field and using translocated substrate as spore traps. 2) It is an effective colonizer of suitable substrate and grows rather fast so the colonizations could be detected within some months. 3) It is rather rare.

Study system 2 – limed mires Liming was used as early as 1920 for favouring fish production. In the late 1960's fish kills and low pH in the lakes in southwest Sweden were found to be related to the deposition of airborne anthropogenic sulphur and nitrogen compounds. In 1977 a liming project of lakes started. This activity became permanent with governmental financial support in 1982 and has increased and is now also occurring in the northern parts of Sweden (Bernes 1991). This works well in large lakes with slow residence time. However, in small shallow lakes and in running water the effect of the liming event fast disappears. To remedy this and especially meliorate the acid surges in the spring the authorities have started to deposit the lime in streams in small but frequent doses by a dosing device or in wetlands to let it slowly leak out in the surrounding limnic environments. This activity is in fact a mas- sive disturbance that highly affects the vegetation, often consisting of acidophilous mire species. Peat mosses Sphagnum spp. which often are the dominant part of the vegetation are killed off and the vascular plant vegetation become denser, with several graminoids especially favoured (Rafstedt 2008). In this study we used this large scale nation- wide transformation of habitats not to study the extinctions of acidophilous species, but instead the colonizations and hence dispersal capacity of species that can withstand high pH-environment.

In a 50 m × 50 m plot in each of the 52 sampled limed mires the abundance (in a scale 1–5) of all bryophytes and vascular plants were recorded. The mire area outside the plot was surveyed for presence of additionally calcicolous species. In each mire was also pH measured

0:21 and five peat samples were taken (to get an indication of the vegetation before the liming event).

We then analysed the occurrences of calicolous wetland species in the surveyed mires. Connectivity measures for several distances (5, 10, 20 km) were calculated from the number of 1 km2 squares with occurrences of at least one strictly calcicolous wetland species (based on records from the Swedish species gateway (www.artportalen.se). A region or study area was defined as 100 km around all the surveyed mires and the number of 1 km2 squares within this area with occurrence of species was used as measure of their respective regional frequency. The relationships between the number of colonized mires and connectivity measures, pH and Sphagnum-content were investigated. Moreover were regional frequency, how often the species produce capsules (for the bryophytes) and spore (or seed) size analysed against which species that colonized and the number of mires that they had colonized.

0:22 Results and discussion

The overall result was that the realized dispersal capacity of the studied bryophyte species was good (both for a pioneer species and species colonizing limed mires).

The simulations from the used mechanistic model (Lagrangian stochastic dispersion model) fitted rather well to the observed colonization pattern especially if observed spore release thresholds in wind variation and humidity were accounted for (III).

Colonizations around a spore source of Discelium showed that the density of spores decreased up to 30–50 m and after that it leveled out. However there were still colonization at the furthest distance both up to 100 m (III) and 600 m (I). The proportion that traveled further than 50 m was approximated to somewhere between 0–10 spores per square metre from this rather small patch source. This implies that dispersal over 1 km is probably not such a rare occasion for this species (cf. Nathan et al. 2008b). This finding initiated the idea of inves- tigating dispersal over longer distances in a core area for the species around Umeå.

In this region where the species is widespread the effect of connectivity on colonization rates of Discelium over one season increased with distance up to the largest scale analysed, 20 km (II). The approxima- tion of the spore source, based on a survey of the focal species in two landscapes, showed that the colonization rates not were unrealistic given a high germination rate. This comply with observations that Discelium seems to be very effective in tracking newly created suitable substrates along forest roads, ditches and in disturbed areas in clear cuts in this area

Extending the temporal scale to 20–30 years in a study of colonization of limed mires gave a similar result of an effective colonization of bryophytes over long distances. Over this time period a high percent- age (61 %, 54 species) of the calcicolous wetland bryophytes in the study area had colonized one or more of the 52 surveyed mires (IV). No effect of the connectivity up to 20 km could be detected in this

0:23 study. However, the average number of bryophytes per mire was sig- nificantly lower in the southern part of the region compared with the middle and the northern part, which might indicate that the relative proximity to areas with higher densities of rich fens in the province of Jämtland influenced the pattern. The species regional frequency (a gradient from common to rare species) and capsule frequency (how often a species produce capsules) showed a positive relationship with the proportion of mires (out of the 52) that a species had colonized, whereas spore size did not. Compared to the bryophytes a much lower number (15 species) and proportion (29 %) of the calcicolous wetland vascular plants in the study area had colonized one or more of the 52 surveyed mires. The species regional frequency showed a positive relationship and seed size showed a negative relationship with the proportion of mires (out of the 52) that a vascular plant had colonized.

As indicated by Fig. 6 the studies in this thesis bridge a gap between previously performed studies, analyzing dispersal over a short time scale (1–30 years) and relatively large spatial scales (0.1–20 km). The figure only incorporates some examples of different kind of studies to show the temporal and spatial context that this thesis addresses. An- other example of a study that combine dispersal over large spatial scales and short temporal scales concluded that connectivity to mires in a circle of 200 km best explained Sphagnum spore deposition over one year (Sundberg 2013). In the lower left hand corner we find studies of spore deposition over hours and days and a few meters (2–15 m) where 2–70 % of the spores were accounted for within the measured distances (Söderström & Jonsson 1989; Miles & Longton 1992b; Stoneburner, Lane & Anderson 1992; Roads & Longton 2003; Sundberg 2005; Pohjamo et al. 2006). This large range shows that there can be a substantial difference in the number of spores available for long-distance dispersal. Two examples from the other end of the gradient with dispersal over large both spatial and temporal scales are a genetic study of Cinclidium species which found an extensive haplo- type sharing between sites on different continents (Piñeiro et al. 2012) and an analysis that showed that floristic similarity between continents in the southern hemisphere could be explained by wind connectivity during the vegetation season for bryophytes, lichens and pteridophytes (Muñoz et al. 2004). The majority of studies have been performed on intermediate temporal and spatial scales. Studies of colonization of newly created habitats indicate a good colonization capacity over a few to tens of kilometers over half a century (Bremer & Ott 1990; Miller & McDaniel 2004; Hutsemékers, Dopagne & Vanderpoorten 2008). On the other hand studies of the spatial distribution and genetic structure in epiphytes indicate a more restricted dispersal for many

0:24 epiphytes from local to landscape scale over the life time of a tree (Hedenås, Bolyukh & Jonsson 2003; Snäll et al. 2004a; b; Löbel, Snäll & Rydin 2006). Also investigation of genetic structure in other species e.g. limnic species over landscape scales show a restricted gene flow (Hutsemékers et al. 2010; Korpelainen et al. 2013), while e.g. a study on a forest floor species on islands could detect no isola- tion by distance (Cronberg 2002). A study of a small scale (20–80 m from a forest) could not show any effect of connectivity on colonization of forest species on a clearcut over a time of 50 years (Hylander 2009)

10000

1000 Other 100 studies 10 This thesis 1 Time (years) 0.1 0.01 0.001 1 1000 Space (km)

Figure 6. Some examples of studies of bryophyte dispersal plotted after which temporal and spatial scale that they have analysed or tested.

One explanation for these different results could be for how long time the substrate has been available for colonization. However, the ephemeral patches of Discelium that are overgrown in a few years time seem often to be colonized (II), while species on trees that last for tens to hundred years seem to strongly positively relate to connectivity (Snäll et al. 2004b; Löbel et al. 2006). The same could be said for bryophytes on calcareous boulders that have been available for colonization for thousands years, and still are structured by connectivity (Virtanen & Oksanen 2007). So even if time per se increase the

0:25 probability for successful colonization, there must also be other factors that could explain the differences in dispersal capacity among bryophyte species.

Another suggestion is that other substrate characteristics such as how easily it is colonized, could increase the probability of colonization after longer distances. It seems more likely that a diaspore comes to rest on a horizontal surface such as a mire or a clay surface compared to a vertical surface of a tree trunk or a boulder. Moreover, could the time the substrate is moist enough for colonization differ between an exposed elevated surface and a clay surface at ground level (cf. Hylander et al. 2005). Also the water-holding capacity of clay or peat compared to bark or stone differ.

Contrary to this, one could argue that species usually are adapted to the substrate they inhabit. Discelium seems certainly adapted to fast occupy a disturbed clay surface and reproduce and disperse to new patches. However, other species can be highly adapted to more harsh substrates but the environment may still limit how fast they can colonize it and grow.

Also in what kind of habitat the species grows could have an effect on dispersal capacity, and the degree of tree cover in the habitat is an important gradient for wind-dispersed organisms (Nathan et al. 2008b). All the studies in this thesis has been performed in open mires (I-IV), while some that have found clear dispersal limitation have been performed in more sheltered habitats (Snäll et al. 2004b; Löbel et al. 2006; Norros et al. 2012). Higher wind speed and wind variation could also trigger spore release under conditions that could favour long-distance dispersal (cf. III) and these are conditions that are more common in open habitats. However, this could to some extent be compensated for by the higher release height for epiphytes.

Not only abiotic factors, but also biotic factors, such as competition, could influence which species that you find in a community (Zobel 1997). Competition between shoots of similar-sized species may rare- ly lead to competitive exclusion (Mälson & Rydin 2009), and can even lead to facilitation under some conditions (Bu et al. 2013). How- ever, in the case of colonization, it might be different. A founder individual could monopolize the habitat and block further colonization (Waters, Fraser & Hewitt 2013). Both of the study systems in this thesis are disturbed habitats that should facilitate colonization (I–IV) and the results have demonstrated a good dispersal and colonization capacity across landscapes. This is in concordance with other studies of

0:26 colonization of bryophytes in disturbed or newly created habitats and substrates such as planted forests, peat pits, mortar and slag heaps (Bremer & Ott 1990; Soro, Sundberg & Rydin 1999; Miller & McDaniel 2004; Hutsemékers et al. 2008).

Transport of diaspores is easily underestimated when studying colonization patterns of a species which is heavily establishment limited. The fact that our study systems were disturbed may be one important explanation to that we managed to show such high colonization across landscapes (II, IV). Many species in other habitats might be confined to small windows of opportunities in space or time to be able to establish (Økland, Rydgren & Økland 2003; Löbel & Rydin 2010) even if they perhaps have dispersed there. If that is the case the spore source strength (how many spore that are available for dispersal) and not small differences in transport capacity of the spores becomes crucial (IV). For wood-inhabiting fungi this seems to be the case, where very large deposition densities could be needed for a successful colonization (Edman, Kruys & Jonsson 2004; Norros et al. 2012). This would imply that generalists, that not only manage to built up much larger source strength but also have a much larger target area of suitable substrates, would be less dispersal limited than specialists (Nordén et al. 2013).

Even if we found a positive relationship between colonization frequency and both capsule frequency and regional frequency (which both influences the source strength) we also found some rare species with small populations in the lowland, like Meesia uliginosa and Catoscopium nigritum, rather frequent in the limed mires (IV). This raises questions on what spatial and temporal scales and for what species connectivity matter. For Discelium, a rather rare species, habitat quality and availability seem to matter much more than connectivity on landscape scales (II).

The results from this thesis can certainly not be generalized to all species since dispersal and colonization can be highly species specific. In many cases it is probably not the transport but the colonization that is be the bottle-neck. However, this thesis highlights the good dispersal capacity in open habitats for many prolific species under relatively short to moderate time scales.

0:27 References

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0:32 Svensk sammanfattning

Att förstå hur och över vilka avstånd arter sprider sig är en viktig grundsten inom olika delar av biologin. Djur kan ofta själva bestämma när och vart de sprider sig, vilket brukar benämnas aktiv spridning. Andra organismgrupper som växter och svampar sprider sina pollen, frön eller sporer passivt med hjälv av t.ex. djur, vatten eller vind. Många arter förlitar sig på vinden för sin spridning, t.ex. svampar, lavar, mossor, ormbunkar, många träd, orkidéer och vissa andra blomväxter. Små lätta spridningsenheter underlättar transporten och många vindspridda pollen och sporer är mellan 5 och 60 mikrometer (ibland upp till 100–200) och orkidéfrön är någon millimeter långa. Större vindspridda frön har ofta t.ex. vingar eller andra strukturer som gör att de kan hålla sig luftburna längre.

Mossor är en samlingsbeteckning för följande gröna växter: bladmossor, levermossor och nålfruktsmossor. I Sverige har vi över 1000 arter av dessa grupper tillsammans och i världen finns det kanske 15 000 eller ännu fler. Mossor sprider sig med sporer men kan också sprida sig med vegetativa förökningskroppar såsom fragment eller groddkorn. De flesta av dessa är dock större än sporer och anses stå för framför allt spridning över kortare avstånd. Förutom en mossfamilj där sporerna sprids med flugor så är nog de flesta andra mossporer till största delen spridda med vinden.

Att sporer är så små gör att de kan vara svårt att studera deras spridning genom att följa deras luftfärd då de knappt syns för blotta ögat. Är man dessutom intresserad av spridning på lite längre avstånd är det ännu svårare. Dessutom är de flesta arters sporer svåra att bestämma ned till art. Jag har i denna avhandling därför istället noterat mosskott som uppkommer när sporerna gror.

I mina tre första studier använde jag flaggmossa Discelium nudum för att uppskatta spridningsavstånd för dess sporer. Den är mycket effektiv på att snabbt kolonisera bar sur lera. Jag grävde upp lera från några meters djup så att det inte skulle finnas några sporer i den från början. Sedan lade jag ut leran på myrar för att den skulle hålla sig fuktig och vara lämplig för kolonisering av flaggmossans sporer.

0:33 Arten sprider sig på våren och på hösten kunde jag avläsa försöken och räkna antalet koloniseringar. I två studier satte jag ut en lerfläck med flaggmossa i mitten av myren och sedan krukor med lera på avstånd upp till 600 m i fyra riktningar i den första studien och upp till 100 m i åtta riktningar i den andra studien för att uppskatta spridningen till olika avstånd. I den ena av dessa studier så bytte jag ut krukorna varannan dag för att kunna relatera spridningen till väderförhållandena som jag också mätte.

Kalkning av myrar sker för att kalk sakta gradvis ska läcka ut i omgivande sjöar och vattendrag för att höja pH där för att gynna fiskar och andra sötvattensdjur. Effekten på myren blir kraftig, vitmossor och andra arter anpassade för de ursprungliga sura förhållandena dör och andra, t.ex. vissa gräs och halvgräs, ökar. I min fjärde studie inventerades kärlväxter och mossor på 52 kalkade myrar 20–30 år efter det första kalkningstillfället. Jag var intresserad av att se vilka kalkgynnade arter som hade spritt sig dit och hur ofta det hade skett. Min frågeställning var om detta kunde påverkas av olika egenskaper hos arterna. Dessutom ville jag undersöka om artsammansättningen och antalet kalkgynnade arter på myren påverkades av antalet kända lokaler för kalkgynnade arter inom olika avstånd från myren.

Jag kunde konstatera att depositionen av flaggmossans sporer avtog kraftigt fram till 50 m, men att depositionen sedan planade ut på en låg nivå ända upp till 600 m. I Umeåområdet, där flagmassan är rätt spridd ,kunde jag konstatera att sambandet mellan hur andel av leran som blivit koloniserad och lämpliga miljöer (lerjordar) i omgivningen ökade när jag räknade med ett större spridningsområde runt varje mätpunkt. Sambandet var starkast med mängden lerjordar i en radie av 20 km, vilket var den största skalan jag undersökte. Modellen som utifrån väderförhållandena förutsade spridning till olika avstånd upp till 100 m beskrev de uppmätta kolonisationerna av flagmossan ganska väl, särskilt när man tog hänsyn till vissa tröskelvärden för när sporerna sprids. Arten släpper troligen sina sporer när det är stor variation i vindhastigheten så att sporer kan skakas ut från kapseln och inte när det är hög luftfuktighet och kapseltänderna stänger till kapselmynningen.

Det var en mycket högre andel av mossorna än kärlväxterna som koloniserade myrarna (från listan på alla kalkgynnade arter i studieområdet). Det tyder på att mossor är bättre på att sprida sig än kärlväxter. En förklaring till detta skulle kunna vara att de har mindre spridningsenheter (sporer är mindre än frön). Mossor med olika sporstorlek spreds lika bra. Däremot bland kärlväxterna koloniserade

0:34 arter med små spridningsenheter fler myrar än de med stora. En förklaring till att arter med små frön ofta koloniserade (förutom att de lätt sprider sig) skulle kunna vara att en art kan bilda många fler spridningsenheter om de är små. Jag hittade ett sådant samband där vanliga mossor som ofta hade kapslar koloniserade fler myrar än arter som är mindre vanliga och hade färre kapslar. Ett liknande samband hittades för kärlväxter.

Antal kalkgynnade arter per myr visade inget samband med hur många förekomster som fanns i närheten av myren upp till 20 km. Däremot konstaterades att i den södra delen av undersökningsområdet var det färre arter än i de två nordligare, vilket skulle kunna bero på att det är de stora områden med högt pH runt t.ex. Storsjön som utgör källan till sporerna.

Mossor som växer i öppna miljöer och ofta bildar rikligt med sporer verkar således ha en god förmåga att sprida sig över avstånd över tiotals kilometrar. Särskilt gäller det vanliga arter. Ibland kan det dock vara mycket korta perioder som är lämpliga för en arts sporer att gro och etablera sig. Det gör att slutsatserna om betydelsen om hur väl en art sprider sig behöver kompleteras med annan informaton för att förstå hur en arts fortlevnadsförmåga skiljer sig från en annans.

0:35 Tack

Till de som tycker att Oscarsgalan har blivit lite torftigare sedan 2010...

Att doktorera kan liknas vid att odla en gröda och förädla skörden från det första utsädet (forskningsfrågeställning) till en färdig produkt på butikshyllan (en publicerad artikel). Först sår man och försöker sköta om plantorna på bästa sätt och till sist skörda. Sedan ska man mala skörden som inte drabbats av missväxt och sälja det som mjöl eller låta det jäsa och sälja surdegsbrödet till ett ännu högre pris. Inte minst vikigt är att paketera det i en attraktiv förpackning för att öka chansen att någon vill köpa varan. Det hela är dock en arbetsintensiv verksamhet och inte minst i det första skedet med många inblandade...

Jag vill tacka de som hjälpte mig att lokalisera lämplig lera och inte minst de som så ekvilibristisk (som en annan använder en smörkniv) hanterade skopan på hjulgrävarna och stod ut med konstiga önskemål och krav. Sedan alla de som hjälpte mig i logistikkedjan från att skyffla leran, transportera den, lagra den, få den i krukor och bära ut den på myrar. Jag vill tacka er, ni stod ut med det hårda kroppsarbetet, leran som letade sig in lite överallt och den uttorkande effekt som lera har på händerna med en liten diktstrof ur Tage Danielssons ”De händer som byggde Göta kanal”:

Genom veckornas knog bar de träget sin börda.. Men så tvätta dom av sig det värsta på lörda

Markägare, personal på länsstyrelser och kommuner är jag också djupt tacksam mot då de genom att ge mig tillstånd att genomföra mina studier och kommit med tips om var jag kan leta lera har möjliggjort insamlingen av rådatat till denna avhandling.

Även ni som hjälpte mig att inventera de kalkade myrarna spridda över halva Sverige är jag djupt tacksam emot. Långa bilresor, regn, sena kvällar, mygg, knott, svidknott, bromsar och myrar som ibland är lite djupare än beräknat har ni utstått.

0:36 Tack alla ni som har gjort vistelsen på botan (vilken när jag började hette växtekologiska avdelningen på botaniska institutionen och när jag slutade institutionen för ekologi, miljö och botanik, Lilla Frescati) till en sådan trevlig tid: alla andra doktorander, seniora forskare och personal.

Tack till min huvudhandledare, biträdande handledare och medförfattare för att ni hjälp mig att lotsa manusen så här långt och så småningom kanske hjälper till att få dem ända in i mål.

Tack till alla er som möjliggjorde alla moment av kursdelen i avhandlingen: De som har arrangerat och deltagit i alla kurser och konferenser jag har deltagit i (t.ex. Ekenäs, Abisko, Lund, Uppsala). Ni som planerade och deltog i doktorandresan till Etiopien. Ni som deltog i bokdiskussioner och hjälpte till att förstå obegripliga figurer och hypoteser. Inte minst ni som anordnade och deltog i litteraturseminarierna. En stor del av de kurser jag har gått har utgjorts av statistik. Jag tror det var Justin Travis som använde det något dubbeltydiga "statistical wizardry". Ska jag hålla fast vid den liknelsen så kan jag konstatera att jag inte har blivit någon Harry Potter men åtminstone lärt mig en del enklare korttrick. De som introducerade mig till denna magiska värld är jag skyldig ett stort tack.

Så här när mer än fyra år har förflutit är det lätt att bli nostalgisk. Biblioteket är en inrättning som verkar ha blivit föråldrad i dagens digitala värld. Både biologibiblioteket och botaniska biblioteket har gått i graven under dessa fyra år och jag tackar för den tiden då det gick att förstrött bläddra i ett nyutkommet nummer av en tidskrift när man hade en stund över eller kopiera en inte ännu digitalt tillgänglig artikel och den benägna hjälp jag har fått av bibliotekarierna.

Tack till lunchgänget på ArtDatabanken.

Tack även till vänner och familj som har gjort att jag har haft ett annat liv än forskningen och för att stått ut med att jag har varit lite frånvarande, inte minst på slutet.

Dags att knyta ihop säcken innan jag börja sjunga Violetta Parra...

Således är det uppenbart att det man lätt kan inbilla sig i sin fåfänga, att en avhandling är en soloprestation är felaktigt (utan det är till stor del ett lagarbete med en person som tar åt sig hela äran). Tack för detta än en gång till alla har gjort denna avhandling möjlig.

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Här följer ett litet appendix i bokstavsordning på förnamnet. I preventivt syfte kan jag passa på att också tacka alla dem som jag har glömt i mitt något förvirrade tillstånd på sluttampen. Hör av dig så ska du få ett dedicerat examplar av avhandlingen med ett tack i versaler!

Aaron Gove: Thank you for the book "A perfect mess - the hidden benefits of dis- order" where I learned that the most unexpected connection could be detected if you avoid too much order on your desk. Ahmed Mohafer: Tack för att du har stått ut med ovannämnda oordning och positiva attityd Alma Strandmark: Tack för ditt upphöljda lugn som sätter perspektiv på tillvaron Anastasia Eklund: Tack för hjälp med sporräkning och hjälp med groningsförsök Andreas Karlsson Tiselius: Tack för att du engagerade hela släkten i att husera substraten och mig i Norrbotten. För lergrävande. För en oförglömlig sommar i Norrbotten där jag fick beundra den bravur du löser logistiska utmaningar under svåra förhållanden. Anita D'Agostino: Tack för snabba svar om semester och annat Anna Herrström: Tack för sällskap på labbet och insikter om klockgentiana Bengt Gunnar Jonsson: Tack för din klurighet och att du betonade att man ska tro på sina resultat Bernard Goffinet: Thank you for effort with the genome of Discelium. Bryndis Marteinsdottir: Takk! Tack för intressanta inblickar i isländska sedvänjor och att du visat var målet för ens effektivitet ska vara Caroline Essenberg: Tack för hjälp med pH-mätningar och information om spindlar. Claes Bergqvist: Tack för att du gått före och visat hur man klarar sig genom den sista tiden. För dina avdelningsöverskridande luncher och uppdateringar om hur Gnesta utvecklas och frodas. Debissa Lemessa: Galatoomi! Thank you for a most entertaining time in room 538 where we have shared . Interesting discussions covering everything from statistical problems to existential questions (or is that the same thing?). The Kafka-like adven- ture of getting a visa to Costa Rica has put my own hardships in perspective. Didrik Vanhoenacker: Tack för ditt artfokus och underfundiga betraktelser. Ingen har jag mött förr eller senare som med sådan entusiasm och pedagogisk finess har förklarat statistik. En drömstart! Ellen Schagerström: Tack för ständiga nya humoristiska vinklar på tillvaron och anordnandet av arbetsledningskursen även om jag inte hade möjlighet att gå den. Emil Johansson: Tack för ditt glada humör och aldrig sinande energi under leriga, tröstlösa förhållanden Eric Meineri: Merci! Thank you for your help with R. The Access connection was invaluable. Erik Häggbom: Tack för all hjälp och inte minst för att du försökt tillgodose mitt omättliga behov av kopieringskartonger. Frida Sjösten: Tack för hjälp med inventering av kärlväxterna på de kalkade myrarna och att du skötte logistiken däromkring på ett excellent sätt Georg Florian Tschan: Tack för diskussioner under litteraturseminarierna och att du har satt en hög ribba för hur tjock en avhandling ska vara.

0:38 Gundula Kolb: Tack för att du visat vilken ambitionsgrad man ska sträva mot och motionsinspiration Hans Lind: Tack för hjälp med klimatkamrar, vindtunnlar och kopieringskartonger. Helena Forslund: Tack för motionsinspiration och tips om cykeltillbehör och annat Henrik Weibull: Tack för all mossinspiration och hjälp med kapselfrekvensbedömning. Håkan Rydin: Tack för att du var opponent på mitt halvtidsseminarium och håller mossflaggan högt inom en annars alltför kärlväxtdominerad värld Ingela Lundwall: Tack för all hjälp med autoklaver och i växthuset Jan Edelsjö: Tack för utdrag ur obsdatabasen och trevliga luncher och expeditioner Jean Baptiste Jouffray: Merci! Thank you for your help e.g. with putting out clay in snow and under the moon. For information on the very long French bird names. Jessica Oremus: Tack för tips och trevliga diskussioner om skidåkning, löpning och annat. Joakim Hansen: Tack för positiva pratstunder om Natura 2000 och annat, ordinationstips och inte minst linserna!! Johan Dahlberg: Tack för trevliga diskussioner om mossor och inte minst hjälp med att hämta hem lerkrukor från Jordbärsmuren med hjälp av skidor och pulka i en begynnande snöstorm. Johan Dahlgren: Tack för hjälp med R och annat. Johan Ehrlén: Tack för uppmuntran och tips och hejarop längs vägen inte minst nu på slutet Johan Klint: Tack för att med otroligt lugn lyssna på alla beklaganden om "hein med data och automata". Juha Loenberg: Tack för att du med ett stoiskt lugn och metodiskhet antog utmaningarna med lerlogistiken Jörgen Rudolphi: Tack för trevliga diskussioner på skrivrum 538 och tips om det ena och andra och emfasering av djur som spridningsvektorer Karin Kjellström: Tack för sällskap på statistikkursen och sedan trevliga samtal på botan Karin Lönnberg: Tack och en av de trevligaste disputationerna jag har varit på Karin Wiklund: Tack för mossinspiration och hjälp med kapselfrekvensbedömning. Jag lyckades dock inte upprepa din bragd att skriva kappan på en helg. Kjell Bolmgren: Tack för exemplaret av Hampus Wilhelm Arnells löfmossornas kalendarium och intressant diskussioner om gamla källor och fenologi. Kristian Hassel: Tack för en trevlig mosskurs med fjäll och kust. Kristoffer Andersson: Tack för att du klarade det hårda tidsschemat med att byta lera på Ryggmossen var och varannan dag Kristoffer Hylander: Som min huvudhandledare har din obotliga optimism oavsett förhållandena och din kreativitet att hitta utvägar ur de mest prekära situationer varit ovärderlig. För att få ett batteri att fungera är det ju en god idé att sätta ihop katoden med anoden. För att du på något underligt sätt alltid hittar tid även när det inte finns någon. Känslan av att spela bordtennis med en kinesisk mästare är påtaglig (bollen (läs manuset) stannar alltid på min sida). Att i skrivarbetet emfasera flytet, pregnansen och läsbarheten under devisen det dunkelt skrivna är det dunkelt tänkta. I vilka sammanhang som något är tillräckligt bra och att man bör tillåta sig att ta ut svängarna och spekulera är några andra lärdomar du givit mig. Tack för allt.

0:39 Lars Hedenäs: Tack för hjälp med bestämning, kapselfrekvensbedömning och litteratur. För mossinspiration och att jag alltid är välkommen på riksmuseet. Leila Ahonen: Tack att du exekverar ladokutdrag, semester och annat alltid med ett leende och glimten i ögat Lena Kautsky: Tack för tips om alger och annat. Lenn Jerling: Tack för att du betonat undervisningens betydelse. Lisa Fors: Tack för ditt engagemang för det kollektiva i form av fester, pubar, IS i en miljö där individualistisk framgång betonas och dina dystopiska betraktelser över sakernas tillstånd. Malie Lessard-Therrien: Merci. Thank you for your stay in 538 and the discussions of Svalbard and other things. Malin König: Tack för att du har följt mig under hela doktorandtiden. Vi startade med en månads mellanrum och avslutar med samma avstånd. Tack för statistiktips, uppmuntran till motion och att ta lunch. Maria Enskog: Tack för hjälp med lerpreparering Marit Persson: Tack för utdrag av rikkärrsarter Martin Schmalholz: Tack för att du gick före och visade vägen, trevlig samvaro och diskussioner och hjälp med krukor vid Krapelåsen Mats Dynesius: Tack för att du upplåtit ditt garage som lagerlokal för lera och logistiknav för lertransporter över Västerbotten och övriga delar av landet. För att du grävde lera och har skickat Discelium. Maya Edlund: Tack för inventering av de kalkade myrarna och en oförglömlig sommar med intressanta diskussioner och sällskap under ibland rätt svåra förhållanden. Jag säger bara Växjö: Störtregn-allting dyblött- din Mossberg blir dubbelt så tjock - missar samtalet från vandrarhemmet – hamnar på ett svindyrt vandrarhem som underlät att säga att det pågick en konsert till kl. 3 på natten alldeles intill. Har man överlevt det så överlever man nog det mesta. För ditt tips att slå flugorna i huvudet Niklas Paulsson: Tack för att du ställde upp med kort varsel och inventerade kalkade myrar Nils Cronberg: Tack för hjälp med kapselfrekvensuppskattning och att har upprättat ett fäste för mossekologi i Skåne. Nils Erik Ericson: Tack för all hjälp med i Umeå med att gräva lera och leta flagmossa, att du har agerat flagmossekurir och att du inventerade kalkade myrar på mossor. Nurun Nahar: Tack för att du ryckte ut och hjälpte mig på Ryggmossen Ola Svensson: Tack för din oförtrutliga hjälp under svåra förhållanden med leran. Du är en av de få som har gjort det under flera säsonger vilket tyder på en enorm karaktärsstyrka och dödsföraktande inställning till livet. Otso Ovaiskainen: Kitos. Thank you for all help and hospitality during my stay in Helsinki and your always quick replies on every question and razor-sharp analyses Ove Eriksson: Tack för tips om frölitteratur och inte minst de litteraturseminarier du anordnade som var intressanta och lärorika. En av höjdpunkterna under doktorandtiden helt klart! Patrick Gullström: Tack för hjälp med leran. Peter Hambäck: Tack för en positiv ledning av institutionen och att din dörr alltid står öppen Peter Litfors: Tack för att du stått ut med all lera och silt i kvantiteter som skulle få vem som helst att blekna och tips och trix i arbetet i växthuset.

0:40 Petter Andersson: Tack för många trevliga diskussioner om dvärghannar, fåglar, skalbaggar, fjärilar och mycket annat. För hjälp med könsbestämning av rikkärrsmossor och planering av doktorandresan. Rasmus Erlandsson: Tack för att du ryckte ut när det behövdes. Sebastian Sundberg: Tack för din noggrannhet där ingen detalj är oväsentlig, kluriga lösningar och idéer och att du tar dig tid och sänder tillbaka manusen klockan tre på natten. Sofi Lundbäck: Tack för dina smarta lösningar och hjälp att hitta mossor i Norrbotten. Sonja Råberg: Tack för trevliga diskussioner på skrivrum 538 om Natura 2000 och mycket annat. Susanne Lindwall: Tack för hjälp med ergonomiska hjälpmedel och annat Svante Holm: Tack för introduktion till genetiken och hjälp med våra försök att få några genetiska uppskattningar av spridningavstånden hos Discelium. Tenna Toftegaard: Tack för lärdomen att om man tycker något är svårt så är det bara att öva mer och utmana sig själv Thomas Verschut: Dank u. Thanks for engaging yourself in the common good and showing me the interesting camera device. Tiina Vinter: Tack för litteraturseminarier, doktorandresa och inte minst lagning av min stråhatt. Tomas Hallingbäck: Tack för hjälp med artbestämning, kapselfrekvensbedömning , illustrationer och litteratur. För mossinspiration och ständigt nya reseförslag. Tove von Euler-Chelpin: Tack för intressanta bokdiskussioner och att du alltid behåller ditt lugn och är en god lyssnare Ulla Rasmussen: Tack för att du hjälpte oss med våra fruktlösa försök att avtvinga Discelium någon genetisk information på individbasis. Ulrika Samnegård: Tack för sällskap på statistikkurser, intressanta biinsikter, en positiv attityd och mycket annat. Urban Gunnarsson: Tack för mossinspiration och hjälp med kapselfrekvensbedömning Veera Norros: Kitos. Thank you for setting a high standard for spore dispersal studies. For all your help, performing the analyses in paper III and hospitality during my stay in Helsinki. Finally I fully agree: dispersal rules!. Veronika Johansson: Tack för tips om Öland, mykorrhiza och fröer, curlingsejouren och planeringen av doktorandresan, arbetet med Plant & Ecology. Att jag fick låna maskinen att smälta ihop sporpåsar med. Victor Johansson: Tack för en skön inställning, trevliga stunder med vindtunnel och fuktkammare och tips och diskussioner om R, statistik, kärlväxter och idiomatiska uttryck. Üllar Rannik: Tänan. Thank you for explaining about the meteorological nomen- clature and performing the simulations in paper III.

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