Evaluating climate signal recorded in tree-ring δ¹³C and δ¹⁸O values from bulk wood and α-cellulose for six species across four sites in the northeastern US - Guerrieri, Rossella (Centre de Recerca Ecològica i d'Aplicacions Forestals) ; Jennings, Katie (University of New Hampshire. Earth Systems Research Center) ; Belmecheri, Soumaya (University of Arizona. Laboratory of Tree Ring Research) ; Asbjornsen, Heidi (University of New Hampshire. Earth Systems Research Center) ; Ollinger, Scott (University of New Hampshire. Earth Systems Research Center)