Ecological research networks functioning across climatic and edaphic gradients are critical for improving predictive understanding of biogeochemical cycles at local through global scales. One international network, the Detrital Input and Removal Treatment (DIRT) Project, was established to assess how rates and sources of plant litter inputs influence accumulations or losses of organic matter in forest soils. DIRT employs chronic additions and exclusions of aboveground litter inputs and exclusion of root ingrowth to permanent plots at eight forested and two shrub/grass sites to investigate how soil organic matter (SOM) dynamics are influenced by plant detrital inputs across ecosystem and soil types. Across the DIRT network described here, SOM pools responded only slightly, or not at all, to chronic doubling of aboveground litter inputs. Explanations for the slow or even negative response of SOM to litter additions include increased decomposition of new inputs and priming of old SOM. Evidence of priming includes increased soil respiration in litter addition plots, decreased dissolved organic carbon (DOC) output from increased microbial activity, and biochemical markers in soil indicating enhanced SOM degradation. SOM pools decreased in response to chronic exclusion of aboveground litter, which had a greater effect on soil C than did excluding roots, providing evidence that root-derived C is not more critical than aboveground litter C to soil C sequestration. Partitioning of belowground contributions to total soil respiration were predictable based on site-level soil C and N as estimates of site fertility; contributions to soil respiration from root respiration were negatively related to soil fertility and inversely, contributions from decomposing aboveground litter in soil were positively related to site fertility. The commonality of approaches and manipulations across the DIRT network has provided greater insights into soil C cycling than could have been revealed at a single site.
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http://dx.doi.org/10.1016/j.scitotenv.2018.05.388 | DOI Listing |
Young tropical secondary forests play an important role in the local and global carbon cycles because of their large area and rapid biomass accumulation rates. This study examines how environmental conditions and forest attributes shape biomass compartments and the productivity of young tropical secondary forests. We compared 36 young secondary forest stands that differed in the time since agricultural land abandonment (2.
View Article and Find Full Text PDFHuan Jing Ke Xue
November 2024
School of Environmental Science and Safety Engineering, Tianjin University of Technology, Tianjin 300384, China.
Different vegetation types may affect the accumulation and transformation of soil organic carbon (SOC), but it is unclear whether the organic carbon fixation is realized by litter input and/or root control of environmental factors and dissolved organic matter (DOM) of soils. In this study, the spatial distribution characteristics of easily oxidizable organic carbon (EOC), dissolved organic carbon (DOC), particulate organic carbon (POC), mineral-bound organic carbon (MAOC), and their seasonal variations in the surface soil (0-10 cm) were studied in different vegetation zones of the arbor forest (at the upper position), the mixed forest of arbor and shrub (at the middle position), and the waterfront vegetation (at the bottom position) in the ecological embankment of Duliujian River, Tianjin, China. The spatial distribution characteristics of soil DOM components and their seasonal changes were also analyzed by combining UV-visible spectroscopy and 3D fluorescence spectroscopy.
View Article and Find Full Text PDFMicroorganisms
November 2024
State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China.
Climate warming and high-intensity human activities threaten the stability of alpine meadow ecosystems. The stability of the soil microbial community is crucial for maintaining ecological service function. However, the effects of warming and litter removal on microbial interactions, community-building processes, and species coexistence strategies remain unclear.
View Article and Find Full Text PDFEcol Appl
December 2024
Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota, USA.
Planting diverse forests has been proposed as a means to increase long-term carbon (C) sequestration while providing many co-benefits. Positive tree diversity-productivity relationships are well established, suggesting more diverse forests will lead to greater aboveground C sequestration. However, the effects of tree diversity on belowground C storage have the potential to either complement or offset aboveground gains, especially during early stages of afforestation when potential exists for large losses in soil C due to soil decomposition.
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