RESEARCH SUMMARY 



Stem analyses in singleleaf pinyon {P-Lnus monophylla) -Utah 

 juniper (Juniperus osteospevma) stands in Nevada and eastern Califor- 

 nia indicate that tree age does not directly affect either diameter 

 or height growth rates. Diameter growth rates are governed primarily 

 by competition, and height growth rates depend largely on genetic 

 characterictics and approach to a site-dependent maximum height. 

 Rates of stand basal area increment vary among stands, but tend to 

 be constant with time within closed stands. Because of its constancy 

 and direct relationship to productivity, stand basal area increment 

 may provide a good index of site quality in closed stands. Total 

 aboveground biomass accumulation rates tend to increase with time, 

 even in older stands. In the absence of perturbations, biomass in 

 pinyon- juniper stands would probably continue to accumulate at 

 nearly constant or slightly increasing rates for several centuries. 



CONTENTS 



Page 



INTRODUCTION 1 



METHODS 1 



RESULTS AND DISCUSSION 2 



Height Growth 4 



Diameter Growth ' 



Stand Basal Area ^ 



Total Aboveground Biomass .... 8 



CONCLUSIONS . 11 



APPENDIX A: EQUATIONS OF ESTIMATING BIOMASS 13 



APPENDIX B: PROCEDURE FOR CALCULATING PAST BIOMASS 14 



APPENDIX C: CROWN MAPS 15 



APPENDIX D: TREE DATA 18 



