干旱区生态环境知识资源中心(Arid): Whole System Carbon Exchange of Small Stands of Pinus Ponderosa Growing at Different CO{sub 2} concentrations in open top chambers

Arid

DOI	10.2172/762792
报告编号	N/A
来源ID	OSTI_ID: 762792
	Whole System Carbon Exchange of Small Stands of Pinus Ponderosa Growing at Different CO{sub 2} concentrations in open top chambers
	Ball, J. Timothy; Ross, Peter D.; Picone, John B.; Eichelmann, Hillar Y.; Ross, Gregory N.
英文摘要	Functional understanding of the carbon cycle from the molecular to the global level is a high scientific priority requiring explanation of the relationship between fluxes at different spatial and temporal scales. We describe methods used to convert an open top chamber into both closed and open flow gas exchange systems utilized to measure such fluxes. The systems described consist of temporary modifications to an open top chamber, and are put in place for several days on one or several open top chambers. In the closed system approach, a chamber is quickly sealed for a short, predetermined time interval, the change in gas concentrations is measured, then the chamber is unsealed and ventilated. In the open flow system approach, airflow into the open top chamber is measured by trace gas injection, and the air stream concentration of CO{sub 2} and water vapor is measured before and after injection into the chamber. The closed chamber approach can resolve smaller fluxes, but causes transient increases in chamber air temperature, and has a high labor requirement. The open flow approach reduces the deviation of measuring conditions from ambient, may be semi-automated (requiring less labor), allows a more frequent sampling interval, but cannot resolve low fluxes well. Data demonstrating the capabilities of these systems show that, in open canopies of ponderosa pine, scaling fluxes from leaves to whole canopies is well approximated from summation of leaf P{sub s} rates. Flux measurements obtained from these systems can be a valuable contribution to our understanding whole system material fluxes, and challenge our understanding of ecosystem carbon budgets.
出版年	1996
报告类型	Technical Report
语种	英语
国家	美国
来源学科分类	54 ENVIRONMENTAL SCIENCES ; CANOPIES ; CARBON CYCLE ; GAS INJECTION ; SAMPLING ; WATER VAPOR ; PINES ; CARBON DIOXIDE ; ECOLOGICAL CONCENTRATION
URL	http://www.osti.gov/scitech/servlets/purl/762792
资源类型	科技报告
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/266813
推荐引用方式 GB/T 7714	Ball, J. Timothy,Ross, Peter D.,Picone, John B.,et al. Whole System Carbon Exchange of Small Stands of Pinus Ponderosa Growing at Different CO{sub 2} concentrations in open top chambers,1996.