tailieunhanh - Báo cáo lâm nghiệp: "Carbon and nitrogen allocation in trees"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài:Carbon and nitrogen allocation in trees. | 631s Ann. Sci. For. 1989 46 suppl. 631s-647s Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA Carbon and nitrogen allocation in trees . Dickson USDA-Forest Service NCFES Rhinelander Wl . Introduction Growth of trees and all plants depends upon maintaining a positive carbon balance despite continually changing environmental stresses. Under natural conditions growth is commonly limited by several environmental stresses operating at the same time. Thus growth is the summation of a plant s response to multiple environmental stresses Chapin et al. 1987 Osmond et al. 1987 . Light carbon water and nitrogen are fundamental factors most likely to limit growth. On a world-wide basis water availability is probably the major factor limiting plant growth Schulze eta . 1987 . However in many temperate and tropical forests nitrogen availability is the most critical limiting factor Agren 1985a . Thus information provided by studies of carbon and nitrogen metabolism and their interactions is necessary to understand plant growth. There has been an enormous amount of research on carbon and nitrogen interactions and plant growth primarily with agricultural plants and primarily directed towards harvestable plant parts. However compared to agronomic crops we have only limited knowledge of carbon and nitrogen interactions and growth for any species in natural ecosystems. Although there have been many studies on component biomass nutrient content and net primary production the results are difficult to interpret and generally do not provide information on changes over time in varying environments. The primary reason for interpretation problems is the lack of standard carbon allocation data sets developed for trees grown under optimum conditions to compare with carbon allocation patterns found in stress situations. A major objective of tree research should be to develop such standard data sets on a few key or indicator species. Then carbon and nitrogen allocation patterns

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