tailieunhanh - Báo cáo lâm nghiệp:"Below-ground resources limit seedling growth in forest understories but do not alter biomass distribution"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài:"Below-ground resources limit seedling growth in forest understories but do not alter biomass distribution" | Ann. For. Sci. 60 2003 319-330 INRA EDP Sciences 2003 DOI forest 2003023 319 Original article Below-ground resources limit seedling growth in forest understories but do not alter biomass distribution José-Luis MACHADOa b Michael B. WALTERSa c and Peter B. REICHa a Department of Forest Resources University of Minnesota 1530 Cleveland Av. North St. Paul MN 55108 USA b Current address Department of Biology Swarthmore College Swarthmore PA 19081 USA c Current address Department of Forestry Michigan State University 126 Natural Resources Building East Lansing MI 48824 USA Received 20 August 2001 accepted 10 May 2002 Abstract - We examined the long-term growth morphology biomass distribution and survival response of seedlings of five conifer species varying widely in shade tolerance to an increase in soil resources in shaded forest understories in northern Wisconsin USA. In a 4-year experiment trenching treatment was used to increase soil resource supply to 1-year old seedlings planted across a range of low light microenvironments. Specifically we asked 1 does an increase in soil resources alter whole-plant growth biomass distribution patterns and survival in lowlight and 2 do species differ in their responses to increasing soil resources Increased soil resource availability increased height 11 on average and dry mass 23 on average of all species regardless of light availability. However there was no evidence that trenching affected biomass distribution for any species as has been previously reported. Survivorship after four years was positively related to the species reported shade tolerance ranking and was unaltered by trenching. We concluded that soil resource availability supply-demand can limit tree seedling growth in deeply shaded forest understories but that increased resource availability of the magnitude caused by trenching does not favor tolerant rather than intolerant species or vice-versa. long-term trenching northern Wisconsin conifer species .

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