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The nitrogen economy of mountain birch seedlings: implications for winter survival
Author(s) -
Weih Martin,
Karlsson P. Staffan
Publication year - 1999
Publication title -
journal of ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.452
H-Index - 181
eISSN - 1365-2745
pISSN - 0022-0477
DOI - 10.1046/j.1365-2745.1999.00340.x
Subject(s) - shading , seedling , growing season , betula pubescens , human fertilization , relative growth rate , agronomy , biology , nutrient , fertilizer , horticulture , botany , growth rate , ecology , art , geometry , mathematics , visual arts
1 Seedlings of mountain birch Betula pubescens ssp. czerepanovii were grown outdoors, under different environmental conditions, during their first growing season at Abisko, northern Sweden. Winter survival of seedlings was studied in relation to their growth and nitrogen (N) acquisition rate during the previous growing season. 2 Effects of fertilization and soil temperature on seedling growth and N acquisition were analysed in a factorial experiment including seven fertilizer levels and two temperature treatments. Effects of shading and neighbours ( B. p. ssp. czerepanovii and Empetrum hermaphroditum ) on seedling growth and N economy were evaluated in another experiment including five different neighbour interaction treatments. 3 An increase in either soil temperature or fertilization rate caused the birch seedlings to take up more N and grow faster. The relative growth rate and rate of N accumulation during the 12‐week growing season were closely related to winter survival: at a relative growth rate of 2.0% and 3.8% day −1 , the winter survival of mountain birch seedlings was estimated to be 5% and 95%, respectively. This range corresponded to a relative N accumulation rate between 2.4% and 4.3% day −1 . 4 The relative N accumulation rate was clearly reduced by shading and by the plant–plant interactions studied. The effects of shading and birch neighbours but not of Empetrum on the rate of N accumulation could be explained by lower soil temperature. 5 Nutrient supply, soil temperature, vegetation shade and, presumably, allelopathy affect the N acquisition of first‐year mountain birch seedlings, and thus also influence their winter survival. Soil temperature might be the major influence on the survival rate, due to its strong influence on the root N uptake rate.