4 research outputs found
Linddynans habitatpreferenser
Linddynan (Biscogniauxia cinereolilacina) Ă€r en sporsĂ€cksvamp som lever pĂ„ död lindved. Svampen Ă€r vĂ€rd Ă„t fyra av de nio rödlistade och vedlevande skalbaggsarter som ingĂ„r i Ă
tgÀrdsprogrammet för skalbaggar pÄ skogslind
(Ehnström, 2006). De fyra arterna: lindbarkbagge (Synchita separanda), lindmögelbagge (Enicmus brevicornis), lindplattbagge (Laemophloeus monilis)och enfÀrgad brandsvampbagge (Diplocoeolus fagi) nyttjar svampen
som föda. Det finns ingen egentlig kunskap kring linddynans habitatpreferenser,annat Àn att den lever pÄ död lindved. För att kunna utföra relevanta naturvÄrdsinsatser för de fyra linddynalevande skalbaggarna Àr det viktigt
att veta nÄgot om förutsÀttningarna som pÄverkar linddynans förekomst.
I denna studie inventerades drygt 200 lindar i park- respektive naturbestÄnd i Stockholms, Uppsala och VÀstmanlands lÀn. Resultaten visar att linddynan, liksom skalbaggarna, kan klara av att leva i skuggig miljö. Det Àr
dock viktigt att de skuggiga förhÄllandena inte skapar ett alltför fuktigt mikroklimat, med bl.a. mosstillvÀxt som följd. Denna har visat sig ha en negativ effekt pÄ förekomsten av linddyna. Eventuellt krÀver linddynan att det finns Àldre trÀd pÄ lokalen för att den ska klara av att etablera sig, men studien har visat att den kan nyttja död ved frÄn yngre trÀd som substrat.
Det Àr troligare att hitta linddyna pÄ grövre ved men det konstaterades att linddyna Àven lever pÄ ved som Àr mindre Àn 4 cm i diameter. Linddynan visade sig ocksÄ förekomma pÄ alla rötstadier hos veden, frÄnsett pÄ den helt nydöda. Vi har Àven funnit att linddynan inte enbart förekommer pÄ
lindlÄgor, nÄgot som man tidigare trott. Fynd gjordes pÄ lÄgor sÄvÀl som pÄ skadade eller döda delar av stammen hos stÄende trÀd.
Linden Àr ett trÀd som i princip alltid bör gynnas. SÄ mycket ved som möjligt, och av alla typer, bör sparas pÄ lokaler som hyser linddyna: oavsett dimension och rötstadium. Detta gynnar Àven skalbaggsarterna inom ÄtgÀrdsprogrammet.In the area around the Swedish lake MÀlaren, there are many records of the saproxylic fungus Biscogniauxia cinereolilacina, living on the dead wood of linden. This fungus is the host of four beetle species: Synchita separanda,Enicmus brevicornis, Laemophloeus monilis and Diplocoeolus fagi, which feed of the fungi. These beetles are part of the nine species included in an action plan from the Swedish Environmental Agency that treat saproxylic
beetles living on Tilia cordata (Ehnström, 2006). However, nothing is known about the habitat preferences of B. cinereolilacina, except that it uses dead wood of linden. To be able to apply adequate conservation actions for
the beetles, more knowledge about what affects the presence or absence of B. cinereolilacina would be useful.
Our study involves observations of over 200 linden in the counties of
Stockholm, Uppsala and VĂ€stmanland. The results show that B. cinereolilacina can live in a shaded environment, as can the beetles. However, too humid and shaded conditions are negative as the presence of the fungus is
negatively correlated to the presence of moss. It has been proposed that B. cinereolilacina requires old linden to be able to establish on a location. Yet, the fungus was found living also on the wood of young linden although in
low frequencies.
B. cinereolilacina was more likely to be found on coarse wood. Still, the fungus was found at lower frequencies on fine wood with a diameter of less than 4 cm. B. cinereolilacina was present on wood of all stages of decay,
except on the wood that died very recently. We also found that the fungus lives on damaged or dead parts of the stem of standing trees and not exclusively on the wood of dead laying trees, which until now has been the common view.
The linden should always be considered for conservation. Additionally, one ought to preserve as much of the dead wood as possible, regardless the size or the decay-level of the wood. This favours B. cinereolilacina as well as all the beetles of the action program
Factors explaining variation in the fecundity of female Baltic salmon (Salmo salar) : the influence of length, body condition and growth rate at sea
Understanding factors influencing variation in fecundity is crucial to manage Atlantic salmon (Salmo salar) populations in the Baltic Sea. Larger individuals usually have a higher size-specific reproductive investment than smaller individuals, thus leading to a higher fecundity. Still, fecundity varies a lot among equally sized individuals and there is little known about what is causing this variation. In this study, I consider the effects of body length, condition and growth rate at sea on fecundity in Atlantic salmon females in the Baltic Sea. I collected fecundity data and data on growth rate history at sea in salmon originating from river DalÀlven, which returned to spawn in mid-July to September 2004-2018, after spending two years at sea. I used scales to analyze marine growth patterns of the salmon. My results show that length is the factor that has the greatest influence on Atlantic salmon fecundity. Nevertheless, the relationship between fecundity, length and body condition varies among these years. In addition, there is a declining trend of how much of the variation in fecundity that can be explained by the interactive effect of length and body condition at the time of return to the river for spawning. Using circuli formation rate and inter-circuli distance as proxies for body growth, I show that growth rate during the first and second year at sea does not add to explain fecundity variation, after accounting for length and body condition. Still, being the factor determining body length, growth rate evidently has a great indirect effect on the fecundity of female Atlantic salmon. Individuals that grew poorly during their first year at sea did not compensate for their poor growth by
growing faster during their second year at sea. In addition, the two growth estimates proved not to be related, which indicates that they are in fact independent factors of marine growth rate.
Though it may be other factors than marine growth patterns that are causing variation in the fecundity of same-sized female Atlantic salmon in the Baltic Sea, limitations to my dataset on growth rate at sea means it is still relevant to contemplate this as an independent factor possibly affecting fecundity. Furthermore, I conclude that it is
important to include the rate at which circuli are formed in addition to the inter-circuli distance when using this method to similar or other studies in the future
Ursprung hos harr (Thymallus thymallus) i Bottenviken och Norra Kvarken : en studie av otolit- och fjaÌllkemi hos kustlekande harr i VaÌsterbottens och Norrbottens kustmiljö
FjĂ€llbacka, VĂ€sterhavet, 1989â2019; Torhamn, södra Egentliga Ăstersjön, 2002â2019; KvĂ€döfjĂ€rden, Egentliga Ăstersjön, 1981â2019; Holmöarna, Bottniska viken, 1989â2019
Inom den nationella miljöövervakningen av kust och hav bedrivs Ă„rligen sedan slutet av 1980-talet ett program för integrerad kustfiskövervakning i fyra nationella referensomrĂ„den, ett vardera i Bottniska viken, Egentliga Ăstersjön, södra Egentliga Ăstersjön och VĂ€sterhavet. Syftet med programmet Ă€r att kartlĂ€gga fiskbestĂ„ndens status samt fiskens hĂ€lsotillstĂ„nd och miljögiftsbelastning för att upptĂ€cka förĂ€ndringar som indikerar storskalig pĂ„verkan av miljöhot som eutrofiering, miljögifter, klimatförĂ€ndringar och andra miljöfaktorer. Detta faktablad sammanfattar resultaten frĂ„n den integrerade kustfiskövervakningen i alla fyra omrĂ„den under tidsperioden 1980â2019