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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Invasive Species and Pollinator Health » Research » Publications at this Location » Publication #222522
Title: Contribution of root vs. leaf litter to dissolved organic carbon leaching through soil.

Author
item Uselman, Shauna
item QUALLS, ROBERT - UNIVERSITY OF NEVADA RENO
item LILIENFEIN, JULIANE - DESERT RESEARCH INST.-UNR

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2007
Publication Date: 8/9/2007
Citation: Uselman, S.M., Qualls, R.G., Lilienfein, J. 2007. Contribution of root vs. leaf litter to dissolved organic carbon leaching through soil. Soil Science Society of America Journal.7(5):1555-1563.

Interpretive Summary: Dissolved organic carbon (DOC) is an important component of carbon cycling in forest ecosystems, and leaching of leaf litter is thought to be the dominant source. The aim of this study was to investigate the importance of DOC originating from root litter relative to leaf litter. Results showed that DOC originating from leaf litter may contribute to organic matter accumulation in the surface soil, whereas DOC originating from root litter may help explain the existence of soil organic matter at greater depths. Thus, in addition to DOC originating from leaf litter, this study showed that DOC originating from root litter also plays a role in soil development by contributing to soil organic matter accumulation, and thus increased soil fertility.

Technical Abstract: Very little is known about dissolved organic matter (DOM) originating from fine roots in forest soils in comparison to DOM originating from leaf litter. To compare the fate of root- versus leaf-derived dissolved organic carbon (DOC), we added 14C-labeled root litter at depths of 10 cm, a “shallow root treatment,” and 40 cm, a “deep root treatment,” and leaf litter to 50 cm column soil microcosms. We analyzed solution leached from columns during a 47-day simulated snowmelt treatment, trapped respired 14CO2, and measured translocation of 14C within columns. In general, total % C losses were substantial and highest for the leaf treatment (8.2% as DOC leaching, 13.4% as translocation, and 14.8% as respiration), intermediate for the shallow root treatment (2.3%, 5.2%, and 3.9%) and lowest for the deep root treatment (2.4%, 1.9%, and 2.9%). However, the %C lost to DOC leaching was similar for the deep and shallow root treatments. As a percentage of total losses (i.e. the sum of DOC leaching, respiration, and translocation), 14C lost as DOC leaching was significantly higher in the deep root treatment compared to other treatments. These observations suggest that leaf-derived DOC may contribute to the formation of an A horizon and even to accumulation of soil organic carbon (SOC) in the B horizon during soil development, either by adsorption or microbial biomass incorporation. The 14C data further showed that root-derived DOC, especially from root litter at greater depths, may help explain both the presence of SOC at depth and a portion of the DOC draining from soil profiles.