Hydro-climatic impacts on soil carbon and nutrient cycling
Soil biogeochemical cycles are strongly dependent upon climatic variables. To study the climatic effects on organic matter decomposition, nutrient mineralization, and greenhouse gas emissions, we employ a mathematical model that tracks how C and N are transferred among chemically and functionally different compartments. The kinetic rates that control the fluxes depend on soil moisture and temperature, which in turn are driven by rainfall and solar radiation. Fluctuations in these external forcing variables propagate through the soil compartments, resulting in spectrum of responses at different time scales.
C and nutrient concentrations in plant, microbial, and animal biomass are inherently linked through a range of biological processes. As a result, carbon-to-nutrient ratios are relatively well conserved in microbes and animals, while they vary widely in plants. Decomposers have a lower C:N ratio than their food (i.e., dead organic matter derived from plant residues), leading to a strong elemental imbalance in their diet, which is compensated by taking up inorganic nutrients, or increasing respiration. Using a global litter decomposition database and a simple stoichiometric model of decomposition, we show how the fraction of respired C increases when litter is particularly nutrient-poor. This pattern is consistent across climates and holds in aquatic systems as well.
Vegetation growth is controlled in various ways by CO2 and water vapor exchanges with the atmosphere. These exchanges are jointly driven by atmospheric transport and the activity of stomata, which permits CO2 diffusion into the leaf while avoiding excessive transpiration. To quantify these exchanges, we are developing a canopy-scale model that couples leaf-level biochemistry, based on the principle of optimal leaf gas exchange, to the leaf energy balance and to atmospheric scalar transport equations. Using this model, we explore how leaf-level processes affect long-term vegetation growth and water use under altered rainfall patterns and CO2 conditions.
Stochastic modeling of ecosystem processes
In parallel to the development of complex soil and vegetation models, we are also developing minimalist eco-hydrological stochastic models that account analytically for climatic variability. In one application, we are investigating whether observed patterns of vegetation water use (transpiration) are consistent with the maximization of ecosystem productivity across climatic conditions. Within a similar, minimalist framework, we are also exploring how hydro-climatic fluctuations affect the mass balance of soil contaminants during phytoremediation.
List of Publications
Papers in peer-reviewed international journals (please email me to request a reprint)
Manzoni S., Vico G., A. Porporato, and G.G. Katul (2013). Biological constraints on water transport in the soil-plant-atmosphere system. Advances in Water Resources, 51, 1, 292-304, doi: 10.1016/j.advwatres.2012.03.016.
Manzoni S., Vico G., Katul G., Palmroth S., Jackson R.B., and A. Porporato (2013). Hydraulic limits on maximum plant transpiration and the origin of the safety-efficiency tradeoff. New Phytologist, doi: 10.1111/nph.12126.
Moyano F., Manzoni S., and C. Chenu (2013). Responses of soil heterotrophic respiration to moisture availability: An exploration of processes and models. Soil Biology and Biochemistry (in press).
Palmroth S., Katul G.G., Maier C.A., Ward E., Manzoni S., Vico G., and R. Oren (2013). On the complementary relationship between nitrogen and water use efficiencies among Pinus taeda L. leaves grown under ambient and enriched CO2 environments. Annals of Botany, doi: 10.1093/aob/mcs268.
Manzoni S., Taylor P., Richter A., Porporato A., and G. Ågren (2012). Environmental and stoichiometric controls on microbial carbon use efficiency in soils. New Phytologist 196, 79–9, doi: 10.1111/j.1469-8137.2012.04225.x.
Manzoni S., Schimel J.P., and A. Porporato (2012). Physical vs. physiological controls on water-stress response in soil microbial communities. Ecology 93(4), 930-938.
Manzoni S., Piñeiro G., Jobbágy E.G., Jackson R.B., and A. Porporato (2012), Analytical models of soil and litter decomposition: Solutions for mass loss and time-dependent decay rates. Soil Biology and Biochemistry 50, 66-76.
Katul G., Oren R., Manzoni S., Higgins C., and M. B. Parlange (2012), Evapotranspiration: a process driving mass transport and energy exchange in the soil-plant-atmosphere-climate system. Review of Geophysics doi:10.1029/2011RG000373.
Konings A. G., Feng X., Molini A., Manzoni S., Vico G., and A. Porporato (2012). Thermodynamics of an idealized hydrologic cycle. Water Resources Research 48, W05527.
Montosi E., Manzoni S., Porporato A., and A. Montanari (2012), An eco-hydrologic model of malaria outbreaks. Hydrology and Earth System Sciences 16, 2759-2769.
Vergütz L., Manzoni S., Porporato A., Novais R., and R.B. Jackson (2012). Global resorption efficiency of N, P, K, Ca, and Mg in plants world-wide. Ecological Monographs82(2), 205–220.
Manzoni S., Molini A., and A. Porporato (2011). Stochastic modeling of contaminated soil phytoremediation. Proceedings of the Royal Society of London A, 467(2135), 3188-3205.
Manzoni S., Vico G., Katul G.G., Fay P.A., Polley W., Palmroth, S., and A. Porporato (2011). Optimizing stomatal conductance for maximum carbon gain under water stress: A meta-analysis across plant functional types and climates, Functional Ecology, 25(3), 456-467.
Manzoni S. and A. Porporato. Common hydrologic and biogeochemical controls along the soil-stream continuum (2011). Hydrological Processes, 25(8), 1355-1360.
Manzoni S., Katul G.G., Fay P.A., Polley W., and A. Porporato (2011). Modeling the vegetation-atmosphere carbon dioxide and water vapor interactions along a controlled CO2 gradient. Ecological Modelling 222, 653-665.
Volpe V., Manzoni S., Marani M., and G. Katul (2011). Leaf conductance and carbon gain under salt stressed and elevated atmospheric CO2 conditions. Journal of Geophysical Research - Biogeosciences 116, G04035.
Vico G., Manzoni S., S. Palmroth, and G.G. Katul (2011). Effects of stomatal delays on the economics of leaf gas exchange under intermittent light regimes. New Phytologist 192: 640–652.
Manzoni S., Jackson R.B., Trofymow J.A., and A. Porporato (2010). Stoichiometric controls on carbon, nitrogen, and phosphorus dynamics in decomposing litter.Ecological Monographs 80, 89-106.
Katul G., Manzoni S., Palmroth S., and R. Oren (2010). A stomatal optimization theory to describe the effects of atmospheric CO2 on leaf photosynthesis and transpiration. Annals of Botany 105, 431-442.
Manzoni S., Katul G.G., and A. Porporato (2009). Analysis of soil carbon transit times and age distributions using network theories. Journal of Geophysical Research - Biogeosciences 114, G04025.
Manzoni S., and A. Porporato (2009). Soil carbon and nitrogen models: Mathematical structure and complexity across scales. Soil Biology and Biochemistry 41, 1355–1379.
Wang L., D’Odorico P., Manzoni S., Porporato A., and S. Macko (2009). Carbon and nitrogen dynamics in southern African savannas: the effect of vegetation-induced patch-scale heterogeneities and large scale rainfall gradients. Climatic Change, DOI: 10.1007/s10584-009-9548-8.
Manzoni S., Jackson R.B., Trofymow J.A., and A. Porporato (2008). The global stoichiometry of litter nitrogen mineralization, Science 321, 684-686.
Manzoni S., Porporato A., and J. P. Schimel (2008). Soil heterogeneity in lumped mineralization-immobilization models. Soil Biology and Biochemistry 40, 1137–1148.
Manzoni S., and A. Porporato (2007). A theoretical analysis of nonlinearities and feedbacks in soil carbon and nitrogen cycles. Soil Biology and Biochemistry 39, 1542–1556.
Manzoni S., Porporato A., D’Odorico P., Laio F., and I. Rodriguez-Iturbe (2004). Soil nutrient cycles as a nonlinear dynamical system. Nonlinear Processes in Geophysics11, 589-598.
Conference papers (most recent invited presentations)
Manzoni S. and A. Porporato (2012). Modeling biogeochemical interactions at multiple scales, The Role of Mountains, Climate, and Landscape in Generating Amazon/Andean Biodiversity, National Evolutionary Synthesis Center Catalysis Meeting, Durham, NC.
Manzoni S., Vico G, Katul G., PalmrothS., Jackson R.B., and A. Porporato (2012). Hydraulic limits on maximum plant transpiration, 29th New Phytologist Symposium, Manchester, UK.
Manzoni S., Schimel J. P., and A. Porporato (2011). Physical vs. physiological controls on water-stress in soil microbial communities, ESA Annual Meeting, Austin, TX, Abstract OOS 42-4.
Porporato A., Manzoni S., and G. Vico (2010). Integrating water, carbon, and nutrient cycling at the landscape scale (Invited). Eos Trans. AGU, Fall Meet. Suppl., Abstract B22E-03.
Porporato A., Manzoni S., Austin A., and J. Schimel (2010). A dynamical system view of rainfall-pulse propagation through biogeochemical cycles (Invited). Eos Trans. AGU, Fall Meet. Suppl., Abstract B24B-04.
Porporato A., Vico G., and S. Manzoni (2010). Sustainable use of water resources and nutrients under stochastic rainfall variability: Ecohydrology of managed ecosystems (Invited). Latsis Symposium 2010, EPFL, Lausanne, Switzerland.
Porporato A., Vico G., and S. Manzoni (2010). Exploring the continuum between rainfed and stress-avoidance irrigation in seasonally-dry regions (Invited). Eos Trans. AGU, Joint Meet. Suppl., Abstract H31A-04.
Manzoni S. and A. Porporato (2010). Stoichiometric vs. hydroclimatic controls on soil biogeochemical processes (Invited). European Geosciences Union General Assembly, Abstract EGU2010-6796.
Porporato A., Manzoni S., Molini A., Rigby J. R., and G. Vico (2010). Biologically-defined extremes: survival and ecosystem shifts under climate change (Invited). European Geosciences Union General Assembly, Abstract EGU2010-14226.
Manzoni S., Vico G., Katul G.G., Fay P.A., Polley W., Palmroth S., and A. Porporato (2009). Optimal leaf water use drives ecosystem water and carbon fluxes in a changing environment (Invited), Eos Trans. AGU, 90(52), Fall Meet. Suppl., Abstract H11I-02.
Manzoni S., and A. Porporato (2009). Hydrologic and biochemical controls on nitrogen cycling in soils (Invited). Grand Challenges in Environmental Engineering and Science: Research and Education, AEESP 2009 Conference, Iowa City, IA.