Nitrogen Can Limit Overstory Tree Growth Following Extreme Stand Density Increase in a Ponderosa Pine Forest
Affiliation
School of Natural Resources and the Environment, The University of ArizonaLaboratory of Tree-Ring Research, University of Arizona
Issue Date
2019-03-01Keywords
Jemez Mountainsdendroecology
tree-ring width
limiting factors
stable carbon isotopes
stand density
water stress
soil nitrogen
soil types
growth limitation
drought
climate
fire
recruitment
mechanisms
mortality
plants
Metadata
Show full item recordCitation
L.A. Marshall, Donald A. Falk, and Nate G. Mcdowell "NITROGEN CAN LIMIT OVERSTORY TREE GROWTH FOLLOWING EXTREME STAND DENSITY INCREASE IN A PONDEROSA PINE FOREST," Tree-Ring Research 75(1), 49-60, (1 March 2019). https://doi.org/10.3959/1536-1098-75.1.49Journal
Tree-Ring ResearchAdditional Links
https://www.treeringsociety.org/Abstract
Extreme stand density increases have occurred in ponderosa pine forests throughout the western U.S. since the early 20th Century, with adverse implications for growth, physiological functioning, and mortality risk. Identifying primary stressors on large, old overstory trees in dense forests can informmanagement decisions to promote resilience and survival. We tested the impact of stand density increase on overstory tree-ring growth, and the relative influence of water and nitrogen, in an old-growth ponderosa pine forest in northern New Mexico subject to variable density increase. We measured annual tree-ring growth and carbon discrimination in trees before stand density increased, in a climatically-similar period post-density increase, and in recent transition to drought. We expected density-driven water stress to drive reduced tree-ring growth in overstory trees in dense stands. We found reduced growth and higher mortality in dense stands, but nitrogen rather than water constrained growth, as determined by carbon isotope discrimination in tree rings, leaf nitrogen concentration, and soil nitrogen supply. In dense stands, less available nitrogen limited photosynthetic rate, leading to reduced assimilation of intracellular C-13 and higher discrimination with low tree-ring growth and a reduced relationship with climate. This unexpected result illustrates that a variety of limiting factors can influence forest dynamics, as density-driven nitrogen limitation interacts with water stress to influence tree growth and physiological functioning.Type
Articletext
Language
enISSN
1536-1098EISSN
2162-4585Sponsors
US Forest Service, Collaborative Forest Restoration Program (CFRP); US Forest Service, Rocky Mountain Research Station (United States Department of Agriculture (USDA) United States Forest Service); Joint Fire Science Program; New Mexico Forest and Woodlands Restoration Institute; US Department of Energy Global Change Education Program (United States Department of Energy (DOE)); Department of Energy-Office of Biological and Environmental Research (United States Department of Energy (DOE))ae974a485f413a2113503eed53cd6c53
10.3959/1536-1098-75.1.49