Nitrogen cycle patterns during forest regrowth in an African Miombo woodland landscape
Melillo, Jerry M.
MetadataShow full item record
Tropical dry forests in eastern and southern Africa cover 2.5 × 106 km2, support wildlife habitat and livelihoods of more than 150 million people, and face threats from land use and climate change. To inform conservation, we need better understanding of ecosystem processes like nutrient cycling that regulate forest productivity and biomass accumulation. Here we report on patterns in nitrogen (N) cycling across a 100‐year forest regrowth chronosequence in the Tanzanian Miombo woodlands. Soil and vegetation indicators showed that low ecosystem N availability for trees persisted across young to mature forests. Ammonium dominated soil mineral N pools from 0‐ to 15‐cm depth. Laboratory‐measured soil N mineralization rates across 3‐ to 40‐year regrowth sites showed no significant trends and were lower than mature forest rates. Aboveground tree N pools increased at 6 to 7 kg N·ha−1·yr−1, accounting for the majority of ecosystem N accumulation. Foliar δ15N <0‰ in an N‐fixing canopy tree across all sites suggested that N fixation may contribute to ecosystem N cycle recovery. These results contrast N cycling in wetter tropical and Neotropical dry forests, where indicators of N scarcity diminish after several decades of regrowth. Our findings suggest that minimizing woody biomass removal, litter layer, and topsoil disturbance may be important to promote N cycle recovery and natural regeneration in Miombo woodlands. Higher rates of N mineralization in the wet season indicated a potential that climate change‐altered rainfall leading to extended dry periods may lower N availability through soil moisture‐dependent N mineralization pathways, particularly for mature forests.
Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Biogeosciences, 124(6), (2019): 1591-1603, doi:10.1029/2018JG004803.
The publisher requires that this item be embargoed until 2019-11-08. Please check back after 2019-11-08.
Suggested CitationArticle: Mayes, Marc, Melillo, Jerry M., Neill, Christopher, Palm, Cheryl, Mustard, Jack, Nyadzi, Gerson, "Nitrogen cycle patterns during forest regrowth in an African Miombo woodland landscape", DOI:10.1029/2018JG004803, https://hdl.handle.net/1912/24564
Showing items related by title, author, creator and subject.
Using indirect methods to constrain symbiotic nitrogen fixation rates : a case study from an Amazonian rain forest Cleveland, Cory C.; Houlton, Benjamin Z.; Neill, Christopher; Reed, Sasha C.; Townsend, Alan R.; Wang, Yingping (Springer, 2009-12-05)Human activities have profoundly altered the global nitrogen (N) cycle. Increases in anthropogenic N have had multiple effects on the atmosphere, on terrestrial, freshwater and marine ecosystems, and even on human health. ...
Fate of nitrogen in riparian forest soils and trees : an N-15 tracer study simulating salmon decay Drake, Deanne C.; Naiman, Robert J.; Bechtold, J. Scott (2005-05-23)We introduced a 15N-NH4+ tracer to the riparian forest of a salmon-bearing stream (Kennedy Creek, Washington, USA) to quantify the cycling and fate of a late-season pulse of salmon-N, and, ultimately, mechanisms regulating ...
Mycorrhizal fungi supply nitrogen to host plants in Arctic tundra and boreal forests : 15N is the key signal Hobbie, John E.; Hobbie, Erik A.; Drossman, Howard; Conte, Maureen H.; Weber, John C.; Shamhart, Julee; Weinrobe, Melissa (NRC Research Press, 2009-02-03)Symbiotic fungi’s role in providing nitrogen to host plants is well-studied in tundra at Toolik Lake, Alaska, but little-studied in the adjoining boreal forest ecosystem. Along a 570 km north–south transect from the Yukon ...