title: Waterlogging in late dormancy and the early growth phase affected root and leaf morphology in Betula pendula and Betula pubescens seedlings.
abstract: The warmer winters of the future will increase snow-melt frequency and rainfall, thereby increasing the risk of soil waterlogging and its effects on trees in winter and spring at northern latitudes. We studied the morphology of roots and leaves of 1-year-old silver birch (Betula pendula Roth) and pubescent birch (Betula pubescens Ehrh.) seedlings exposed to waterlogging during dormancy or at the beginning of the growing season in a growth-chamber experiment. The experiment included 4-week dormancy (Weeks 1-4), a 4-week early growing season (Weeks 5-8) and a 4-week late growing season (Weeks 9-12). The treatments were: (i) no waterlogging, throughout the experiment ('NW'); (ii) 4-week waterlogging during dormancy (dormancy waterlogging 'DW'); (iii) 4-week waterlogging during the early growing season (growth waterlogging 'GW'); and (iv) 4-week DW followed by 4-week GW during the early growing season ('DWGW'). Dormancy waterlogging affected the roots of silver birch and GW the roots and leaf characteristics of both species. Leaf area was reduced in both species by GW and DWGW. In pubescent birch, temporarily increased formation of thin roots was seen in root systems of GW seedlings, which suggests an adaptive mechanism with respect to excess soil water. Additionally, the high density of non-glandular trichomes and their increase in DWGW leaves were considered possible morphological adaptations to excess water in the soil, as was the constant density of stem lenticels during stem-diameter growth. The higher density in glandular trichomes of DWGW silver birch suggests morphological acclimation in that species. The naturally low density of non-glandular trichomes, low density of stem lenticels in waterlogged seedlings and decrease in root growth seen in DWGW and DW silver birch seedlings explain, at least partly, why silver birch grows more poorly relative to pubescent birch in wet soils.
authors.affiliation: Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, PO Box 68, FI-80101 Joensuu, Finland School of Forest Sciences, University of Eastern Finland, PO Box 111, FI-80101 Joensuu, Finland aifang.wang@luke.fi.
authors.forename: Ai-Fang
authors.initials: AF
authors.lastname: Wang
authors.affiliation: Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, PO Box 68, FI-80101 Joensuu, Finland.
authors.forename: Marja
authors.initials: M
authors.lastname: Roitto
authors.affiliation: Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, PO Box 68, FI-80101 Joensuu, Finland.
authors.forename: Sirkka
authors.initials: S
authors.lastname: Sutinen
authors.affiliation: School of Forest Sciences, University of Eastern Finland, PO Box 111, FI-80101 Joensuu, Finland.
authors.forename: Tarja
authors.initials: T
authors.lastname: Lehto
authors.affiliation: Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, PO Box 68, FI-80101 Joensuu, Finland.
authors.forename: Jaakko
authors.initials: J
authors.lastname: Heinonen
authors.affiliation: College of Horticulture, Agricultural University of Hebei, 071001 Baoding, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Natural Resources Institute Finland (Luke), Natural Resources and Bioproduction, PO Box 68, FI-80101 Joensuu, Finland.
authors.forename: Tapani
authors.initials: T
authors.lastname: Repo
mesh_terms: D029662:Betula / Q000033:anatomy & histology* / Q000254:growth & development; D057445:Plant Dormancy; D018515:Plant Leaves / Q000033:anatomy & histology / Q000254:growth & development; D036226:Seedlings / Q000033:anatomy & histology / Q000254:growth & development; D014197:Trees / Q000033:anatomy & histology* / Q000254:growth & development; D014867:Water
chemical_list: D014867:Water
keywords: hydraulic conductivity; hypoxia; root characteristics; stem lenticel; stomata; trichome