Impact of afforestation on earthworm populations in Iceland

Earthworms were collected from different vegetation types in East and West Iceland. The vegetation types in East Iceland were Siberian larch (Larix sibirica) forests, native mountain birch (Betula pubescens) woodlands and open heathlands. The study areas in West Iceland were Sitka spruce (Picea sitchensis), lodgepole pine (Pinus contorta) forests, mountain birch woodlands and open heathlands. Four earthworm species (Dendrobaena octaedra, Dendrodrilus rubidus, Aporrectodea caliginosa, Lumbricus rubellus) were identified at both study areas and two additional ones in the West Iceland (Aporrectodea rosea and Octolasion cyaneum). No significant differences were detected in average earthworm species number and biomass between treeless heathlands and forests in East or West Iceland. There were, however, significant differences between the native deciduous forests and the coniferous plantations in West, but not East Iceland. Time since afforestation was found to have a significant effect on both earthworm diversity and density and should always be included in future studies. All earthworm parameters were positively related to soil N and amount of monocots, but negatively related to soil C/N ratio, tree LAI and tree height. Soil pH had no significant influence on any of the earthworm parameters. The most noteworthy finding was that earthworms were generally found in similar biomass and species richness in the exotic coniferous plantations in Iceland compared to the treeless heathlands, even if earthworm species composition showed strong changes. The findings apply to the first 50 years after establishment of coniferous trees, but an unexpected, large increase in earthworm biomass and species richness in the oldest thinned Siberian larch forests in East Iceland make any generalisation about future trends uncertain. Further earthworm studies in the oldest coniferous forests in Iceland are therefore still needed.Áhrif skógræktar á tegundafjölda, þéttleika og lífmassa ánamaðka á Íslandi Ánamöðkum var safnað í mismunandi gróðurlendum á Austur- og Vesturlandi í verkefninu SkógVist. Á Austurlandi voru rannsakaðir rússalerki- og birkiskógar, auk beitts mólendis. Á Vesturlandi voru það sitkagreni-, stafafuru- og birkiskógar og beitt mólendi. Fjórar ánamaðkategundir fundust í báðum landshlutum (mosa-, grá-, garð- og svarðáni) og tvær til viðbótar á Vesturlandi (blá- og rauðáni). Ekki reyndist vera neinn marktækur munur á tegundafjölda, þéttleika eða lífmassa ánamaðka á milli skóglauss mólendis og ræktaðra barrskóga eða birkiskóga á Austur- og Vesturlandi. Á Vesturlandi var tegundafjöldi, þéttleiki og lífmassi ánamaðka marktækt lægri í greni- og furuskógunum miðað við birkiskógana, en á Austurlandi var lífmassi ánamaðka marktækt hærri í (gömlum) lerkiskógum. Ánamaðkar sýndu jákvætt samband með nitri í jarðvegi og magni einkímblöðunga í botngróðri, en neikvætt samband við kolefnis/nitur hlutfall í jarðvegi, laufflatarmálsstuðul og yfirhæð skóga. Sýrustig jarðvegs hafði engin markæk áhrif á ánamaðkasamfélagið. Það vekur athygli hversu hár tegundafjöldi og lífmassi ánamaðka var í íslenskum barrskógum, eða síst minni en í mólendi, þrátt fyrir að tegundasamsetning þeirra breyttist mikið. Niðurstöðurnar sýna hvað gerist fyrstu 50 árin eftir að barrskógar eru gróðursettir, en þær miklu breytingar sem komu fram á ánamaðkasamfélaginu í elstu lerkiskógunum gera allar spár erfiðar um hvað gerist í framhaldinu. Þörf er því á frekari ánamaðkarannsóknum í elstu barrskógum landsins

Áhrif snemmgrisjunar og áburðargjafar á jarðvegshita og jarðvegsöndun í asparskógi

The main goal of this study was to determine the short-term effects of forest management practices (precommercial thinning and fertilization) on soil CO2 efflux of a young black cottonwood (Populus trichocarpa) plantation in southern Iceland. Changes in leaf area index, tree growth, soil and air temperatures were also monitored during the first year following the management period. Traditional precommercial thinning (50%) had little effect on soil temperature, but heavy thinning (80%) led to higher soil temperatures in spring and summer. Thinning did not change foliage nutrient content or tree growth in the first treatment year. Effects on soil CO2 efflux were surprising; even if soil temperature was slightly higher and all organic material was left at site after precommercial thinning, soil CO2 efflux in the thinned stands was significantly lowered. Fertilization increased foliage nutrient content but did not significantly change tree growth during the first growing season following spring application. It did however significantly increase soil CO2 efflux rate in the first treatment year. These results are important when the effects of early forest management on carbon fluxes are modelled.Meginmarkmið rannsóknarinnar var að kanna skammtímaáhrif skógræktaraðgerða, nánar tiltekið grisjunar og áburðargjafar, á jarðvegsöndun í íslenskum asparskógi. Einnig var fylgst með trjávexti, laufflatarmáli og breytingum á loft- og jarðvegshita. Hefðbundin snemmgrisjun (50%) hafði lítil áhrif á jarðvegshita. Mikil grisjun (80%) jók jarðvegshita að vori og sumarlagi en hafði lítil áhrif yfir veturinn. Grisjun hafði engin áhrif á magn næringarefna í laufi eða trjávöxt fyrsta árið. Áhrif grisjunar á jarðvegsöndun voru nokkuð óvænt: hún minnkaði marktækt í kjölfar grisjunar, þrátt fyrir að hitastig hafi hækkað og allt lífrænt efni sem féll til við grisjun hafi verið skilið eftir á skógarbotni. Einu áhrif áburðargjafar á trjávöxt fyrsta árið komu fram í auknu magni næringarefna í laufi. Jarðvegsöndun jókst hins vegar marktækt í kjölfar áburðargjafar. Þessar niðurstöður geta komið að gagni við gerð hermilíkana af áhrifum skógræktaraðgerða á kolefnishringrás og kolefnisbindingu

Icelandic Agricultural Sciences: Alþjóðlegt tímarit á ensku fyrir vísindagreinar í lífvísindum

Hér er fjallað um alþjóðlega vísindaritið Icelandic Agricultural Sciences (IAS) sem gefið er út af Bændasamtökum Íslands, Hólaskóla – Háskólanum á Hólum, Landbúnaðarháskóla Íslands, Tilraunastöð Háskóla Íslands í meinafræði á Keldum, Rannsóknastöð skógræktar á Mógilsá, Landgræðslu ríkisins og Veiðimálastofnun. Megin áhersla er lögð á efnistök og birtingar í ritinu síðustu fimm árin (2003-2007) og grein gerð fyrir því hversu auðfundið efnið er í leitarvélum. IAS hefur sína eigin heimasíðu, www.ias.is þar sem hægt er að fá leiðbeiningar um birtingar í ritinu og nálgast rafræn afrit af öllum vísindagreinum sem birst hafa í því

Hversu sýnilegt er “Icelandic Agricultural Sciences” í alþjóðlegum vefsetrum?

Alþjóðlega vísindaritið Icelandic Agricultural Sciences (IAS) birtir greinar um hagnýt og fræðileg efni í náttúruvísindum. Tímaritið er í prentaðri útgáfu og í opnum rafrænum aðgangi. Greinar í IAS koma fram í ýmsum alþjóðlegum vefsetrum. Leit var framkvæmd í vefsetrum Web of Science og Scopus þann 21. nóvember 2014 til að kanna hversu sýnilegt IAS er. Alls voru 42 IAS greinar (2009-2013) í Thomson gagnagrunni og 36 (2010-2013) í Scopus gagnagrunni, sem eru allar greinar sem komu út í IAS á þessu árabili. Vitnað hefur verið í þessar 42 og 36 greinar 90 og 70 sinnum, að meðaltali 2,1 og 1,9 tilvitnanir í hverja grein. Matsstuðull (e. Impact Factor) er nú 0,071. SJR (SCImago Journal Rank) er 0,211 og SNIP (Source Normalized Impact per Paper) er 0,213. Hirsch-index mælist fimm. Sú grein sem oftast var vitnað í fjallar um öskufall og áfok. Web of Science vefsetrið flokkar greinarnar sem vitna í IAS í 33 svið og Scopus vefsetrið í 18 svið. Höfundar að greinunum sem vitna í IAS eru frá 128 stofnunum og háskólum víðs vegar í heiminum, í fimm heimsálfum og 33 löndum. Vefsetursgreiningin á IAS endurspeglar árangursríkt gæðastarf tímaritsins, fjölbreytt fræðasvið hagnýtra náttúrufræða og gefandi alþjóðlegt samstarf. Árangur útgáfustarfsins er góður og IAS er vel sýnilegt meðal vísindarita sem það er sett í flokk með

Icelandic Agricultural Sciences er nú viðurkennt ISI-vísindarit

Íslensk náttúra á margt sameiginlegt með náttúru annarra landa. Erlendar rannsóknaniðurstöður eru íslenskum vísindamönnum gagnlegar og þeim kynnast þeir í námi, í erlendum ritum, prentuðum eða rafrænum, og með alþjóðlegu samstarfi til dæmis á ráðstefnum. Á hinn bóginn er mikilsvert fyrir íslenska vísindamenn að koma sínum rannsóknaniðurstöðum til skila á erlendum vettvangi og þá helst í viðurkenndum miðlum en um leið þar sem mestar líkur eru á því að alþjóðasamfélagið finni íslenskar rannsóknaniðurstöður. Mikið er skrifað um okkar málaflokk á íslensku en umræða innan samfélagsins er á okkar máli og er þá ekki aðgengileg fyrir erlenda fræðimenn utan okkar málsvæðis. Icelandic Agricultural Sciences býður upp á að merkustu niðurstöður íslenskra rannsókna komist á framfæri á alþjóðavettvangi og opnar fyrir faglega umræðu og innlegg erlendis frá. Ritið styrkir íslenska menningu og vísindastarf með því að gera okkar fræðasvið sýnilegt á einum stað í frumskógi vísindarita

Lífmassaföll og dýptardreifing grófróta birkis á Suðurlandi

Root systems are an important pool of biomass and carbon in forest ecosystems. However, most allometric studies on forest trees focus only on the aboveground components. When estimated, root biomass has most often been calculated by using a fixed conversion factor from aboveground biomass. In order to study the size-related development of the root system of native mountain birch (Betula pubescens Ehrh. ssp. czerepanovii), we collected the coarse root system of 25 different aged birch trees (stem diameter at 50 cm length between 0.2 and 14.1 cm) and characterized them by penetration depth ( 5 mm and > 2 mm), root stock, total belowground biomass and aboveground biomass components were calculated by a nonlinear and a linear fitting approach. The study showed that coarse root biomass of mountain birch was almost exclusively (> 95 weight-%) located in the top 30 cm, even in a natural old-growth woodland. By using a cross-validation approach, we found that the nonlinear fitting procedure performed better than the linear approach with respect to predictive power. In addition, our results underscore that general assumptions of fixed conversion factors lead to an underestimation of the belowground biomass. Thus, our results provide allometric functions for a more accurate root biomass estimation to be utilized in inventory reports and ecological studies.Rótarkerfi trjáa innihalda umtalsverðan lífmassa og traust mat á honum skiptir máli til dæmis þegar kolefnisforði skóga er metinn. Langflestar rannsóknir á trjáa lífmassaföllum (spálíkön út frá bolþvermáli) hér og erlendis hafa hinsvegar einskorðast við ofanjarðarlífmassa þeirra. Þegar reynt hefur verið að áætla rótarlífmassa hefur hann yfirleitt verið metinn sem fast hlutfall af ofanjarðarlífmassa. Í þessari rannsókn voru 25 birkitré á mismunandi aldri (bolþvermál þeirra í 50 cm frá jörðu var 0,2 – 14,1 cm) uppskorin á Rangárvöllum. Allt rótarkerfi þeirra var grafið upp og þvermál róta og dýptardreifing ákvörðuð. Lífmassaföll voru síðan reiknuð fyrir magn grófróta (> 5 og 2 mm), rótarháls (stubb), heildarlífmassa rótarkerfis og ofanjarðarlífmassa með ólínulegu aðhvarfi. Niðurstöðurnar sýndu að nánast allan rótarlífmassa birkis (> 95%) var að finna í efstu 30 cm jarðvegs. Ólínulegu lífmassaföllin lýstu vel hvernig rótarlífmassi breyttist með aldri og ennfremur að það að meta hann sem fast hlutfall af ofanjarðarlífmassa leiðir til umtalsverðs vanmats á honum. Þessar niðurstöður geta því nýst vel þegar rótarlífmassi birkis er metinn fyrir kolefnisúttektir og aðrar vistfræðilegar rannsóknir

Supporting Information Holmstrup et al Appendix 2

Abundance of Collembola species, groups, and species richness. Community-weighted traits

New arthropod herbivores on trees and shrubs in Iceland and changes in pest dynamics: A review

This paper is a review of the history of the introduction of arthropod herbivore species to Iceland since the beginning of the 20th century. A total of 27 new arthropod herbivore species on trees and shrubs have become established in Iceland during this period. One of the introduced pest species, the pine woolly aphid, has been considered to be the major cause of the almost total eradication of the introduced Scots pine in Iceland. The rate of introduction was found to be highest during warm periods. Outbreaks of pests in birch woodlands were also found to be most severe during warm periods. Other pest species have shown changes in outbreak patterns since 1990. The consequences of these findings for isolated native forest ecosystems and a growing forest resource in Iceland are discussed.Nýjar tegundir liðfætlna á trjám og runnum á Íslandi Í þessari grein er rakin landnámssaga nýrra liðdýrategunda sem lifa á trjám og runnum á Íslandi. Frá byrjun tuttugustu aldar til ársins 2012 hafa alls 27 slíkar tegundir numið hér land. Ein þessara tegunda, furulús, er talin hafa verið meginorsakavaldur að dauða nær allrar skógarfuru hér á landi. Hraði landnáms reyndist vera mestur á hlýskeiðum og skordýrafaraldrar í birkiskógum reyndust einnig vera mestir á hlýskeiðum. Eftir 1990 hafa orðið verulegar breytingar á faraldsfræði annarra meindýra í skógum hér á landi. Í greininni er fjallað um hugsanleg áhrif nýrra meindýra og breytinga á faraldsfræði meindýra á innlend skógarvistkerfi og vaxandi skógarauðlindir landsins

Data from: Functional diversity of Collembola is reduced in soils subjected to short-term, but not long-term, geothermal warming

1. Human activities have caused global changes of atmospheric chemistry resulting in increased temperature especially in the colder regions of the northern hemisphere. Since warming of the environment can have drastic effects on terrestrial ecosystems it is important to experimentally evaluate the extent of such effects in long-term field-based experiments. In the present study we make use of both recent (short-term) and long-term geothermal warming of Icelandic soils to examine the responses of Collembola, an ecologically important group of soil invertebrates, to warming. 2. Based on metabolic scaling theory, we hypothesized that species of small size would be more successful in warmed soils than species of larger size. Further we expected that top-soil dwelling species would benefit more from warming than deep-soil dwelling species. In order to test these hypotheses we sampled Collembola along replicated gradients of increasing temperature in areas that had been heated for about six years and more than 50 years, respectively. Collembola were identified to species level, counted, and the community-weighted mean trait scores for six functional and ecological traits were calculated. 3. Results show that both short-term and long-term soil warming caused a shift towards a higher relative abundance of species with small body size. Further, abundance of top-soil dwelling Collembola tended to increase after short-term warming, but the opposite was observed after long-term warming. 4. Using trait-based diversity indices (Frich and RaoQ), we show that functional richness and diversity of Collembola communities was significantly reduced (almost halved) as a result of short-term soil warming to about 10 °C above normal, but this effect was not detected in plots equally warmed for more than 50 years. This indicates that the functional diversity of Collembola communities have high resilience towards soil warming in a long-term perspective

Carbon and water balance of an afforested shallow drained peatland in Iceland

Funding Information: This research was supported by the Energy Research fund of Landsvirkjun, the National Power Company of Iceland, with an additional support from the Iceland State Electricity. It also contributes to the Nordic CAR-ES project ( C entre of A dvanced R esearch on E nvironmental S ervices from Nordic Forest Ecosystems) and to the SNS 120 program (Nordic Forest Research on Anthropogenic greenhouse gas emissions from organic forest soils: improved inventories and implications for sustainable management). Publisher Copyright: © 2020 The Author(s)Drainage of peatlands increases the depth of the oxic peat layer and can turn them into a carbon (C) source to the atmosphere. Afforestation of drained peatlands could help to reverse this process since the trees may enhance C sequestration. We followed the C and water dynamics of an afforested drained peatland in S-Iceland during a 2 year period, during which the Black Cottonwood (Populus balsamifera ssp. trichocarpa) plantation was 23–25 year old. Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured with the eddy covariance method and C pools of trees and ground vegetation were measured using the stock change method. Lateral losses of dissolved and particulated organic C (DOC, POC) were estimated from weekly water-runoff samples. Unexpectedly, the afforested drained peatland was a strong sink of carbon during the two years, with an average NEE value of 714 g C m−2 yr−1. Only 0.5% of the total NEE was lost through lateral DOC and POC transport, leaving 710 g C m−2 yr−1 as the total net ecosystem production (NEP). Ca. 91% of the observed NEP could be explained by the annual biomass increment of the Black Cottonwood trees and 1.3% by the ground vegetation. This means that the remaining 7.5% of the total NEP most likely accumulated in peat soil and litter, contributing to the soil C stocks. The dormant-season CO2 emissions were unexpectedly low, which was explained by a high groundwater level at this drained site outside the ca. 5 months of the active growing season. On average, 66% of the annual measured precipitation was estimated to have evaporated back to the atmosphere. This left 416 mm for potential runoff, which was somewhat lower value than the measured runoff (662 mm). These results indicate that during the age span of ca. 20–25 years, afforestation was a valid method to reverse the expected negative C-balance of this drained grassland pasture in Iceland. Although the site is currently a soil C sink, simulation studies with process models are needed to test whether such sites could remain C sinks when managed for forestry over several tree-stand rotations.Drainage of peatlands increases the depth of the oxic peat layer and can turn them into a carbon (C) source to the atmosphere. Afforestation of drained peatlands could help to reverse this process since the trees may enhance C sequestration. We followed the C and water dynamics of an afforested drained peatland in S-Iceland during a 2 year period, during which the Black Cottonwood (Populus balsamifera ssp. trichocarpa) plantation was 23–25 year old. Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured with the eddy covariance method and C pools of trees and ground vegetation were measured using the stock change method. Lateral losses of dissolved and particulated organic C (DOC, POC) were estimated from weekly water-runoff samples. Unexpectedly, the afforested drained peatland was a strong sink of carbon during the two years, with an average NEE value of 714 g C m−2 yr−1. Only 0.5% of the total NEE was lost through lateral DOC and POC transport, leaving 710 g C m−2 yr−1 as the total net ecosystem production (NEP). Ca. 91% of the observed NEP could be explained by the annual biomass increment of the Black Cottonwood trees and 1.3% by the ground vegetation. This means that the remaining 7.5% of the total NEP most likely accumulated in peat soil and litter, contributing to the soil C stocks. The dormant-season CO2 emissions were unexpectedly low, which was explained by a high groundwater level at this drained site outside the ca. 5 months of the active growing season. On average, 66% of the annual measured precipitation was estimated to have evaporated back to the atmosphere. This left 416 mm for potential runoff, which was somewhat lower value than the measured runoff (662 mm). These results indicate that during the age span of ca. 20–25 years, afforestation was a valid method to reverse the expected negative C-balance of this drained grassland pasture in Iceland. Although the site is currently a soil C sink, simulation studies with process models are needed to test whether such sites could remain C sinks when managed for forestry over several tree-stand rotations.Peer reviewe