No description available.

Temperature is commonly suggested to be the most important regulating factor for the position of the treeline. But also other abiotic and biotic processes may influence. To understand treeline shifts, it is necessary to improve the knowledge about the treeline forming species and their establishment, growth and survival. What are the drivers behind the shifts? The abundance of other vegetation is previously reported to facilitate growth of seedlings above treeline and also warmer temperatures are commonly observed to improve growth.   This study observed growth of mountain birch seedlings during one growing season. The relative importance of environmental factors in relation to the amount of growth and abundance was investigated. The study was conducted in the area of Abisko, Northern Sweden, using 4 sites, where transects were established just above the treeline. The sites differed in the amount of mean precipitation and aspect of the slopes. The vegetation composition around the seedlings and at the average treeline was observed, soil temperatures measured and the aspect of the slope estimated   Seedling growth was observed at all sites, with the highest amount in the sites with most precipitation, Pålnoviken and Katterjåkk. The observed soil mean and maximum temperatures were consistently highest in the southern facing slopes of Jiebrenjåkk and Pålnoviken. The vegetation was mostly dominated by dwarf shrubs, herbaceous plant cover, mosses and bare ground, and did not differ between the seedlings and the average treeline. The best model for growth was found to be the combination of the factors site, herbaceous plant cover, litter and soil mean temperature. Herbaceous plant cover was observed to improve the amount of growth in the drier sites of Pålnoviken and Jiebrenjåkk.   The finding of mountain birch seedlings growing in all vegetation types along the treeline, indicates that they have no preference of vegetation type for establishment. However, the negative influence of bare ground on growth supports the theory that abundance of vegetation facilitates growth of seedlings. The highest amount of growth was found in the sites with most precipitation, suggesting this to be an important factor for growth. In contrast to the expectations, warmer soil temperatures and the south facing slopes did not affect growth positively. This could be explained by the extremely high temperatures of the summer that may have induced drought. Finally, the improved growth by herbaceous plant cover in the drier sites may be because of their preference of moisture and nutrient rich soils, that could also support the growth of mountain birch seedlings.

No description available.

Treelines in high-mountain regions are constrained by heat deficiency, although the working mechanisms are still not entirely understood. Observational and paleoecological studies on treeline performance may contribute to increased understanding of the treeline phenomenon in general. The present thesis addresses elevational shifts of alpine treelines in the Swedish Scandes. By various analytical tools, the studies embrace widely different temporal scales. The concept treeline refers to the elevation (m a.s.l.) at a specific site of the upper individual tree of a certain tree species, at least 2 m tall. All the principal tree species in the Scandes are concerned, i.e. mountain birch (Betula pubescens ssp. czerepanovii), Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). Paper I deals with regional treeline dynamics at more than 100 sites over the past 100 years. Concurrent with temperature rise by c. 1.4 °C over the same period, maximum treeline advances of all species amount to about 200 m. Thus, under ideal conditions, treelines respond in close equilibrium with air temperature evolution. However, over most parts of the landscape, treeline upshifts have been much smaller than 200 m, which relates to the combined action of geomorphology, wind, snow distribution and soil depth. After 1975, the birch has lost its role as the most rapidly advancing tree species, being superseded by pine and spruce. Paper II is a short-term (2005/2007-2010/2011) study of mountain birch treeline performance along a regional maritimity-continentality gradient. Upshift by 3.0 yr-1 in the maritime part of the gradient contrasts to retreat by 0.4 m yr-1 in the continental part. In the latter area, earlier and more complete melting of late-lying snow patches has seemingly progressed to a state when soil drought sets back the vigour of existing birches and precludes sexual regeneration and upslope advance of the treeline. In the maritime area, extensive and deep snow packs still exist above the treeline and constrain its position, although some release is taking place in the current warm climate. Paper III explores treeline change by phenotypic transformation of old-established stunted and prostrate spruce individuals (krummholz) growing high above the treeline and is based on analyses of radiocarbon-dated megafossils, preserved in the soil underneath clonal groups of spruce. Living spruce clones, which in some cases may date back to the early Holocene (9500 cal. yr BP), suggests that spruce immigrated from “cryptic” ice age refugia much closer to Scandinavia than conventionally thought. As the krummholz form presupposes open and windy habitats, it is inferred that permanently open spots prevailed in the high-mountain landscape even during periods when treelines in general were much higher than today. Paper IV reports radiocarbon dates of wood samples, retrieved from newly exposed glacier forefields at three main sites, located high above the modern treelines and embracing the entire Swedish Scandes. It appears that pine colonized early emerging nunataks already during the Late Glacial. Around 9600-9500 cal. yr BP a first massive wave of tree establishment, birch and pine, took place in “empty” glacier cirques. Both species grew 400-600 m above their present day treeline position and accordingly, the summer temperatures may have been 3.5 °C warmer than present (uncorrected for land uplift). During the entire interval 9600 to 4400 cal. yr BP, birch prospered 100-150 m above the uppermost pines. In response to Neoglacial cooling, treelines of both birch and pine descended until their final disappearance from the record 4400 and 5900 cal. yr BP, respectively. Thereafter, these habitats experienced increased snow accumulation and glacier inception. / Avhandlingen belyser förskjutningar i olika tidsskalor av den alpina trädgränsens läge i de svenska Skanderna. Trädgränsen definieras som den högsta nivån (m ö.h.) för minst 2 m höga individer av en viss art i en definierad del av en fjällsluttning. Avhandlingen består av fyra separata uppsatser, publicerade i olika välrenommerade vetenskapliga tidskrifter.  I Paper I analyseras förändringar av trädgränserna för fjällens vanligaste trädarter, fjällbjörk, gran och tall (Betula pubescens ssp. czerepanovii, Picea abies och Pinus sylvestris) mellan 1915 och 2007. Undersökningen omfattar ett 8000 km2 stort, naturgeografiskt heterogent område, med mer än 100 lokaler. De maximala trädgränsförskjutningarna för samtliga trädarter uppgår till omkring 200 m. Resultaten motsvarar de trädgränsförskjutningar som teoretiskt kan förutsägas utifrån den temperaturhöjning med cirka 1,4 °C som skett under samma tidsperiod, förutsatt ideala förhållanden. För större delen av området råder emellertid andra, icke-ideala förhållanden, varför trädgränsernas uppflyttning i allmänhet blivit avsevärt mindre än 200 m. Den främsta anledningen till detta är lokala topoklimatiska begränsningar, d.v.s. kombinerade effekter av geomorfologi, vind, snöfördelning, jorddjup, etc., som i stora delar av det starkt brutna fjällandskapet mer eller mindre effektivt hindrar träden från att nå sina potentiellt högst belägna växtplatser betingade av temperaturen. Efter 1975 har björken förlorat sin roll som arten med den snabbast expanderande trädgränsen. I stället har tall och gran avancerat med större hastighet. Det innebär att även om klimatets uppvärmning fortsätter, så kommer det subalpina björkbältet att expandera i avsevärt mindre omfattning än vad som ofta förebådats. Möjligtvis kommer det att ersättas av tall. Paper II behandlar björkens trädgränsdynamik under perioden 2005/2007-2010/2011 längs en regional klimatgradient med avseende på maritimitet/kontientalitet. Trädgränsen har under den aktuella perioden avancerat 3,0 m/år i den maritimt präglade delen av gradienten, vilket kontrasterar signifikant mot en sänkning med 0,4 m/år i området med mer kontinentalt klimat. Skillnaderna diskuteras i termer av klimatförändringens varierande effekter på snötäckets utbredning och varaktighet och dess inverkan på markfuktigheten. En allt tidigare total utsmältning av snölegorna i de kontinentala områdena har av allt att döma resulterat i vattenbrist under sommaren. Torka medför reducerad vitalitet för existerande björkar och förhindrar både sexuell förökning och uppflyttning av trädgränsen. I de maritima delarna kvarligger alltjämt mycket snö under en stor del av sommaren. Trädgränsens position har därför kunnat bibehållas eller flyttas upp. Vissa omständigheter tyder på att trädgränsens stigning i högre grad har varit baserad på fröföryngring efter 1975, jämfört med perioden 1915-1975. Utgångspunkten för Paper III är erfarenheter från Paper I, som visar att trädgränsens uppflyttning för gran och björk huvudsakligen är resultatet av ökad höjdtillväxt av äldre, i vissa fall flertusenåriga, mer eller mindre buskformiga individer (krummholz), som vuxit på nivåer långt ovanför trädgränsen. Som ett svar på de senaste hundra årens varmare klimat har dessa antagit trädform, varigenom trädgränsen höjts. För en fördjupad förståelse av den här mekanismen har megafossil, d.v.s. grova vedrester bevarade i marken under gamla grankloner i trädgränsekotonen, 14C-daterats. Resultaten tyder på att granar i exponerad fjällmiljö kan uppnå i det närmaste ”evigt” liv genom sin förmåga till vegetativ förökning och möjligheten att växla mellan busk- och trädform i takt med klimatets växlingar. Vissa nu levande kloner existerade av allt att döma redan för 9500 år sedan. Den nu dokumenterat tidiga förekomsten av gran, bekräftar den på senare tid allt tydligare bilden av granen som en tidig invandrare till fjällkedjan. Möjligtvis har granen ”övervintrat” den senaste istiden närmare Skandinavien än vad som till helt nyligen varit den gängse uppfattningen. Paper IV behandlar en för Skandinavien ny metod för historisk trädgränsrekonstruktion. I uppsatsen analyseras 14C-dateringar av totalt 78 större veddelar (megafossil) som nyligen exponerats i anslutning till smältande glaciäris och ”perenna” snölegor i tre huvudområden, Helags-Sylarna, Tärna och Abisko, högt ovanför dagens trädgräns. Det framkommer att tall (Pinus sylvestris) koloniserade tidigt framsmälta nunatakker redan under senglacial tid. För omkring 9600-9500 år sedan inträffade en första massiv våg av björk- och talletablering i isfria glaciärnischer. Båda arterna växte 400-600 m ovanför sina nuvarande trädgränspositioner, i ett klimat som kan ha varit 3,5 °C varmare än idag. Under intervallet 9600 till 4400 BP uppträdde björken i ett 100-150 m brett bälte ovanför de översta tallarna. Som ett svar på klimatets successiva avkylning under senare delen av Holocen sänktes både björkens och tallens trädgränser i de aktuella miljöerna, till dess de för 4400 respektive 5900 år sedan helt försvann från lokaler där glaciärer och perenna snöfält började bildas. De analyserade trädresterna, som länge bevarats av glaciäris och perenn snö representerar en period med ett klimat långt varmare än under det senaste århundradet. Med denna analogi från det förflutna kan det därför antas att i en framtid där sommartemperaturerna rent hypotetiskt är 3,5 °C högre än i nutiden, skulle trädgränserna lokalt kunna flyttas upp med ungefär 600 m.

In response to the furniture industry’s growing demand for raw material, large volumes of juvenile silver birch and downy birch stems available from pre-commercial thinning operations in Sweden’s forests could offer solutions. However, such stems are not currently used on an industrial scale, and most research conducted on birch stems in general has neither focussed on young trees nor the potential use of the central stem part around the tree pith. The resulting lack of knowledge about the juvenile part of birch wood thus requires additional information about the material properties of birch, which could encourage its use for various purposes in the furniture and other industries. The initial literature review performed for this thesis has highlighted some properties of juvenile birch required for its use as a furniture material, as well as identified topics concerning the physical characteristics of juvenile birch about which knowledge is currently limited. Consequently, the objectives of this thesis were to explore some characteristics of juvenile birch—bark thickness, wood-to-bark bonding ratio after drying, variations in the density and width of growth rings, and anatomical growth response to fertilisation—in order to increase the knowledge. The material studied came from mixed birch and Norway spruce stands at two sites in southern Sweden, namely Asa and Toftaholm. The birch stems were naturally regenerated silver birch and downy birch, with breast height diameters between 30 and 83 mm. Fertilised and unfertilised silver birch trees were sampled at Toftaholm, whereas unfertilised stems of silver birch and downy birch were sampled at Asa. The characteristics of stems from the pith to bark (radial direction) and along the stem (longitudinal direction) were measured. The wood-to-bark bonding ratio on downy birch after drying was calculated as the percentage of the stem circumference with full contact between the wood and bark, while oven-dry density and basic wood density for silver birch were determined by using the water displacement method. The impact of ring width on wood density was statistically analysed, and an image analysis of the wood anatomy was conducted to elucidate their relationship. Amongst the results, bark thickness along the stem had the highest deviation in the section closest to the stump. Moreover, the wood-to-bark bonding ratio after drying measured for juvenile downy birch seemed to depend more on the stem’s diameter than the sampling height along the stem. Such results are relevant for processors seeking to estimate the volume of wood under the bark. The wood-to-bark bonding ratio was highest for diameters between 30 and 39 mm, and neither did that relationship correlate with the sampling height along the stem. Variation in wood density in the radial and longitudinal directions in juvenile silver birch suggested that such density negatively correlated with growth rate (ring width). That relationship held true for stems at each site and between the sites, irrespective of management or growing conditions. As expected, mean wood density was lower in fertilised trees than in unfertilised ones, and towards the bark, radial density increased more in trees that grew more slowly. At the same time, variation in longitudinal density in young silver birch trees was low. Quantitative wood anatomy studies confirmed that the fertilised juvenile birch had younger cambia, thinner cell walls, and fewer vessels per mm2 than unfertilised trees in the same diameter class. Overall, the knowledge generated in the study may facilitate the industrial use of juvenile birch stems and wood in interior and furniture applications. The role of wood anatomy in determining the mechanical performance of juvenile birch stems should be further examined, however, to possibly reveal new opportunities for the use of juvenile birch. / Det finns ett växande behov av råvaror till möbelindustrin. Stammar av juvenil vårtbjörk och glasbjörk finns tillgängliga i stora volymer från röjning i svenska skogar. För närvarande finns det inget storskaligt industriellt nyttjande av det virket. Bättre kunskap om dess virkesegenskaper kan öppna upp möjligheterna till olika användningsområden. Dock har en majoritet av den befintliga björkforskningen ofta exkluderat studier av innersta veden närmast kärnan, vilket resulterat i en låg kunskapsnivå om det juvenila virket. I den inledande litteraturstudien i denna uppsats belyses vilka krav som ställs på materialegenskaperna i möbelvirke. Vidare identifieras befintliga kunskapsluckor i fysiska och mekaniska egenskaper för juvenil björk. Målet med denna uppsats är därför att utforska några egenskaper, såsom barktjocklek, barkvidhäftning efter torkning, densitet och årsringsbreddsvariation samt hur gödsling kan påverka vedanatomin. Materialet kom från blandskogsbestånd med gran och björk i Asa och Toftaholm i Götaland. Björkarna var självföryngrad vårtbjörk och glasbjörk och stammarna hade en brösthöjdsdiameter mellan 30 och 83 mm. I Toftaholm var en del av beståndet gödslad respektive ogödslad vårtbjörk. Från Asa togs stammar av både vårtbjörk och glasbjörk. Virkesegenskaper och dess variationer i stammens radiella och longitudinella riktning studerades. Vidhäftningen av barken till veden efter torkning bedömdes procentuellt på omkretsen av ändträet. Relativ torrdensitet och rådensitet mättes. Påverkan av årsringsbredd på veddensitet analyserades statistiskt och vedanatomin studerades med mikroskop och bildanalys för en vidare förståelse av dess samband med gödsling. Resultaten gällande barktjocklekens variation visade att den nedre delen av stammen hade störst medelavvikelse. Dessa resultat kan vara relevant information för vidareförädling efter avbarkning. Barkens vidhäftning till veden efter torkning mättes på juvenil glasbjörk. Det visade ett visst samband med stamdiameter där den högsta vidhäftningen fanns på stammarna med en diameter mellan 30 och 39 mm. Sambandet var däremot inte korrelerat till stamhöjden där provet togs. Densitetsvariation i radiell och longitudinell riktning studerades för juvenil vårtbjörk. Densiteten hade en svag negativt korrelation till årsringsbredd. Detta samband sågs både inom bestånd och mellan bestånd med olika tillväxtförhållande samt skötsel. Medeldensiteten för virket var, som förväntat, lägre i de gödslade träden jämfört med de ogödslade. I den radiella riktningen  hade det senvuxna virket en högre faktor på densitetsökningen. Den longitudinella densitetsvariationen i unga vårtbjörkar var låg. Kvantitativa vedanatomistudier bekräftade att ungdomsveden i gödslad vårtbjörk hade en lägre kambiumålder, tunnare cellväggstjocklek och färre kärl jämfört med ogödslade träd med samma diameter, resultat som tidigare påvisats för mogen björk. Sammanfattningsvis kan resultaten från den här uppsatsen förbättra kunskapen och därmed underlätta för en industriell användning av juvenila björkstammar inom inredning och möbler. Dock bör vedanatomins påverkan på de mekaniska egenskaperna för juvenila björkstammar studeras vidare. Det kan möjliggöra nya användningsområden för juvenil björk.

Lic.-avh (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 3 uppsatser.

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv., 2003. / Härtill 6 uppsatser.

Against the background of past, recent and future climate change, the present thesis addresses elevational shifts of alpine treelines in the Swedish Scandes. By definition, treeline refers to the elevation (m a.s.l.) at a specific site of the upper trees of a specific tree species, at least 2 m tall. Based on historical records, the first part of the thesis reports and analyzes the magnitude of treeline displacements for the main trees species (Betula pubescens ssp. czerepanovii, Picea abies and Pinus sylvestris) since the early 20th century. The study covered a large and heterogeneous region and more than 100 sites. Concurrent with temperature rise by c. 1.4 °C over the past century, maximum treeline advances of all species amount to about 200 m. That is virtually what should be predicted from the recorded temperature change over the same period of time. Thus, it appears that under ideal conditions, treelines respond in close equilibrium with air temperature evolution. However, over most parts of the landscape, conditions are not that ideal and treeline upshifts have therefore been much smaller. The main reason for that discrepancy was found to be topoclimatic constraints, i.e. the combined action of geomorphology, wind, snow distribution, soil depth, etc., which over large parts of the alpine landscape preclude treelines to reach their potential thermal limit. Recorded treeline advance by maximum 200 m or so over the past century emerges as a truly anomalous event in late Holocene vegetation history. The second part of the thesis is focused more on long-term changes of treelines and one specific and prevalent mechanism of treeline change. The first part of the thesis revealed that for Picea and Betula, treeline shift was accomplished largely by phenotypic transformation of old-established stunted and prostrate individuals (krummholz) growing high above the treeline. In obvious response to climate warming over the past century, such individuals have transformed into erect tree form, whereby the treeline (as defined here) has risen. As a means for deeper understanding of this mode of positional treeline change, extant clonal spruces, growing around the treeline, were radiocarbon dated from megafossil remains preserved in the soil underneath their canopies. It turned out that Picea abies in particular may attain almost eternal life due to its capability for vegetative reproduction and phenotypic plasticity. Some living clones were in fact inferred to have existed already 9500 years ago, and have thus persisted at the same spot throughout almost the entire Holocene. This contrasts with other tree species, which have left no living relicts from the early Holocene, when they actually grew equally high as the spruce. Thereafter they retracted by more than 300 m in elevation supporting that also on that temporal scale, treelines are highly responsive to climate change. The early appearance of Picea in the Scandes, suggests that Picea “hibernated” the last glacial phase much closer to Scandinavia than earlier thought. It has also immigrated to northern Sweden much earlier than the old-established wisdom. The experiences gained in this thesis should constitute essential components of any model striving to the project landscape ecological consequences of possible future climate shifts.

There is much evidence that herbivory is a key innovation for the tremendous success of insect. In this thesis I have investigated different aspects of host plant utilization and phenotypic plasticity using the polyphagous comma butterfly, Polygonia c-album. Even though external conditions affect a phenotypic plastic response, the outcome is often influenced by a genetic background which may differ among populations. In Paper I we suspected the genetic background to seasonal polymorphism to be X-linked. However, results from interspecific hybridization between two populations suggested that diapause response is instead inherited in a mainly autosomally additive fashion, with a possible influence of sexual antagonism on males. In Paper II we showed that female oviposition preference is not a plastic response influenced by larval experience, but has a genetic background coupled to host plant suitability. Further, there is a strong individual correlation between larval host plant acceptance and female host plant specificity (Paper III). We believe this to be a larval feed-back genetically linked to female host specificity: offspring to ‘choosy’ specialist mothers benefit by remaining on the original host while offspring to less discriminating generalist mothers should risk inspecting the surroundings, thus compensating for potential poor female choice. In the larval mid-gut, genes are differentially expressed depending on host plant diet (Paper IV). Therefore, we expected to find fitness consequences of host plant switch. However, although growth rate was affected in a few treatments, larvae were generally surprisingly good at adjusting to new diets (Paper V). To conclude, host plant choice in both female and larval life stage is connected to performance. Combined with increased understanding about the plastic response to diet intake and seasonal polymorphism we have gained further insights into the processes of local adaptations and speciation in the Lepidoptera. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted Manuscript; Paper 5: Manuscript

Abstract Disturbance may shift microbial communities from one state to another. However, species differ in their ecological characteristics and their abilities to withstand disturbance. No single species or individuals of a species exist alone, but they are parts of complex interaction networks including species above- and belowground. In boreal and subarctic forests, almost all plants and a high number of fungi form mycorrhizas at the plant roots. In mycorrhiza, the fungal partner harvests nutrients for the host plant and, in return, gains carbon from the plant. In general, these common associations benefit both partners, but as heterotrophs, fungi are dependent on carbon photosynthesized by plants, whereas plants can survive alone as autotrophs. In addition to mycorrhizal fungi, also other fungi, such as endophytes, saprotrophs and pathogens, live in and on plant roots. This thesis concerns the impacts of disturbance on fungi living in plant roots and in soil near the roots. I hypothesized that i) root-associated fungal (RAF) and soil fungal communities and colonization types change after disturbance, that ii) the observed shifts relate to disturbance intensity and that iii) they co-occur with changes in soil conditions and vegetation. Changes in RAF were studied as changes in root fungal colonization, or in fungal community composition. The latter were detected with next-generation sequencing methods. The responses of RAF to disturbance seemed to be context dependent and related to sources of fungal communities (e.g. soil, RAF networks), environmental conditions (e.g. soil pH and nutrients) and host performance. It seems that abundances of those RAF species, which are present in the roots first (priority effect), may be increased by disturbance. Research produced new information related to ecological roles of the genera Phialocephala and Meliniomyces. Altogether, the results indicate connections between both abiotic and biotic environments and RAF, and host species viability and RAF. / Tiivistelmä Häiriöt voivat siirtää eliöyhteisön tilasta toiseen. Lajien ominaisuudet ja häiriönsietokyvyt eroavat toisistaan. Mikään laji tai yksilö ei elä yksin, vaan lajit ovat osa maan ylä- ja alapuolelle ulottuvia monimutkaisia vuorovaikutusverkostoja. Boreaalisissa ja subarktisissa metsissä lähes kaikki kasvit ja useat sienet muodostavat sienijuuren eli mykorritsan. Mykorritsassa sieniosakas hankkii isäntäkasville ravinteita ja saa vastavuoroisesti kasvilta hiiltä. Tavallisesti nämä vuorovaikutussuhteet hyödyttävät molempia sienijuuren osakkaita, mutta toisenvaraisina (heterotrofeina) sienet ovat riippuvaisia kasvien yhteyttämästä hiilestä, kun taas tuottajina (autotrofeina) kasvit voivat elää itsenäisesti. Mykorritsasienten lisäksi kasvien juurissa elää yleisesti myös muita sieniä kuten endofyyttejä, saprotrofeja ja patogeeneja. Tämä väitöskirja käsittelee häiriön vaikutuksia sieniin, jotka elävät kasvien juurissa ja juuria ympäröivässä maassa. Hypoteesieni mukaan i) juurissa ja maassa elävien sienten yhteisöt ja kolonisaatiotyypit muuttuvat häiriön jälkeen, ii) muutokset liittyvät häiriön voimakkuuteen ja iii) muutokset tapahtuvat samanaikaisesti maan olosuhteiden ja kasvillisuuden muutoksien kanssa. Juurissa elävien sienten esiintymisen muutokset tutkittiin sienten kolonisaation tai yhteisörakenteen muutoksina. Sieniyhteisöt selvitettiin NGS-menetelmien avulla. Juurissa elävien sienten vasteet häiriöön vaikuttavat olevan tilannesidonnaisia ja liittyvän sienilajien lähteisiin (esim. maa, juurisieniverkostot), ympäristömuuttujiin (esim. maan pH, ravinteet) ja isäntäkasvin menestymiseen. Häiriö voi vahvistaa juurissa ensimmäisenä läsnä olevien sienilajien menestymistä (prioriteettivaikutus). Uutta tietoa tuotettiin Phialocephala ja Meliniomyces –sienisukujen ekologiasta, jota tunnetaan huonosti. Kaiken kaikkiaan, tulokset osoittavat yhteydet sekä elottoman ja elollisen ympäristön ja juurten sieniyhteisön että isäntäkasvin elinkyvyn ja juurten sieniyhteisön välillä.