tailieunhanh - Báo cáo lâm nghiệp: "Morning, noon, or afternoon: does timing of direct radiation influence the growth of Picea abies seedlings in mountain forests?"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài:"Morning, noon, or afternoon: does timing of direct radiation influence the growth of Picea abies seedlings in mountain forests?" | Ann. For. Sci. 62 2005 697-705 INRA EDP Sciences 2005 DOI forest 2005058 697 Original article Morning noon or afternoon does timing of direct radiation influence the growth of Picea abies seedlings in mountain forests Peter BRANGa Stefanie VON FELTENa b Sven WAGNERc a WSL Swiss Federal Institute of Forest Snow and Landscape Research Zurcherstrasse 111 8903 Birmensdorf Switzerland b Current address Institute of Environmental Sciences University of Zurich Winterthurerstrasse 190 8057 Zurich Switzerland c Institut fur Waldbau und Forstschutz Technische Universităt Dresden Pienner Str. 8 01737 Tharandt Germany Received 5 July 2004 accepted 18 May 2005 Abstract - We studied the influence of the timing of direct sunlight on the growth of Picea abies seedlings in a field experiment on a northfacing slope in the subalpine zone of the Swiss Alps. Vertical walls were established to expose three-year-old P. abies seedlings to direct sunlight at different times of day morning noon afternoon and to diffuse light only during two growing seasons. The light treatments were chosen in order to simulate microsites in forest gaps with different orientations. While the light treatments resulted in different daily soil temperature curves they affected neither average growing season soil temperature nor the frequency of soil temperatures above 10 C which are assumed to be particularly beneficial for seedling growth. Final seedling biomass was unaffected by the timing of direct sunlight but lower for seedlings receiving diffuse light only. These findings suggest that the orientation of slit-shaped gaps in subalpine forests to promote P. abies seedling growth is unimportant. gap orientation seedling growth time of day of direct radiation Picea abies soil temperature Résumé - Le matin à midi ou l après-midi le moment du rayonnement direct influence-t-il la croissance des semis de Picea abies en forêt de montagne Nous avons étudié si le moment du rayonnement direct pendant la journee