Production and quality of spring sap from Alaskan birch (Betula neoalaskana sargent) in Interior Alaska

Abstract

Little is known about the specifics of spring sap production in Alaskan birch Betula neoalaskana Sargent. With an emerging industry in Alaska based on the harvest of birch sap, additional information is needed. This thesis is an exploratory study that investigates the production of sap during the 2002 and 2003 spring seasons in the Fairbanks region and characterizes the dissolved solid components of the sap harvested in 2003. April 2002 and 2003 had strongly contrasting weather patterns which affected sap yields. In general, trees yielded more sap in the wet, cool spring of 2002 than the dry, warm spring of 2003. Larger diameter trees yielded more sap in both years, and this correlation was stronger during the dry, warm spring. Stand location on the hillside and indicator species were also related to sap yield. Carbohydrate content of birch sap is mostly glucose (44%) and fructose (40.3-54.6%); sucrose and galactose are also present. The relative concentration of carbohydrates varied throughout the sap season. Macronutrients (Ca, K, and Mg) and micronutrients (Mn, Fe, Al, Na, Zn and Cu) are present in the sap; their concentrations increase throughout the season.