Without canopy-opening fire disturbances, shade-tolerant, fire-sensitive species like red maple (Acer rubrum L.) proliferate in many historically oak-dominated forests of the eastern U.S. Here, we evaluate potential implications of increased red maple dominance in upland oak forests of Kentucky on rates of leaf litter decomposition and nitrogen (N) cycling. Over 5 years, we evaluated mass loss of leaf litter and changes in total N and carbon (C) within six leaf litter treatments comprised of scarlet oak, chestnut oak, and red maple, and three mixed treatments of increasing red maple contribution to the leaf litter pool (25, 50, and 75% red maple). Over a 1.5-year period, we conducted a plot-level leaf litter manipulation study using the same treatments plus a control and assessed changes in net nitrification, ammonification, and N mineralization within leaf litter and upper (0–5 cm depth) mineral soil horizons. Red maple leaf litter contained more “fast” decomposing material and initially lost mass faster than either oak species. All litter treatments immobilized N during initial stages of decomposition, but the degree of immobilization decreased with decreasing red maple contribution. The leaf litter plot-level experiment confirmed slower N mineralization rates for red maple only plots compared to chestnut oak plots. As red maple increases, initial leaf litter decomposition rates will increase, leading to lower fuel loads and more N immobilization from the surrounding environment. These changes may reduce forest flammability and resource availability and promote red maple expansion and thereby the “mesophication” of eastern forests of the U.S.
|Number of pages||13|
|State||Published - Dec 2014|
Bibliographical noteFunding Information:
This research was supported by the Joint Fire Science Program (01-3-3-14, 04-2-1-06) and would not have been possible without the field and laboratory help of Millie Hamilton, Jessi Lyons, Jamison Paul, Gretchen Carmean, Autumn Foushee, Michael Mahala, Stephen Bell, Amy Herberg, Adam Sovkoplas, Elizabeth Carlisle, and many others. We are also grateful to our collaborators at the U.S. Forest Service who assisted with field set-up and data collection, and to Megan Poulette, Matt Weand, and Ryan McEwan who provided insightful comments and suggestions throughout this study. This study (#14-09-011) is connected with a project of the Kentucky Agricultural Experiment Station.
© 2014, Springer Science+Business Media New York.
- fire suppression
- leaf litter
- red maple
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Environmental Chemistry