Tomer Duman

University of New Mexico | UNM · Department of Biology

The eddy covariance method is widely used to investigate fluxes of energy, water, and carbon dioxide at landscape scales, providing important information on how ecological systems function. Flux measurements quantify ecosystem responses to environmental perturbations and management strategies, including nature‐based climate‐change mitigation measur...

Earth’s ecosystems are increasingly threatened by “hot drought,” which occurs when hot air temperatures coincide with precipitation deficits, intensifying the hydrological, physiological, and ecological effects of drought by enhancing evaporative losses of soil moisture and increasing plant stress due to higher vapor pressure deficit (VPD). Drought...

Large datasets of greenhouse gas and energy surface-atmosphere fluxes measured with the eddy-covariance technique (e.g., FLUXNET2015, AmeriFlux BASE) are widely used to benchmark models and remote-sensing products. This study addresses one of the major challenges facing model-data integration: To what spatial extent do flux measurements taken at in...

Exploration of the flow inside the roughness sublayer often suffers from sub-sampling of its complex three-dimensional and non-homogeneous flow fields. Based on detailed particle image velocimetry within a randomly-ordered canopy model, we analyze the potential differences between single-location flow statistics and their spatially-averaged values....

The increase in large-scale land cover change (LCC) in recent decades, particularly in response to climate-driven disturbances, has potential to impact local and regional changes in climate due to modification of carbon sources and sinks, albedo, surface roughness and energy fluxes. Using observational data, we predict the impact of two of the most...

Climate‐driven woody vegetation mortality is a defining feature of semiarid biomes that drives fundamental changes in ecosystem structure. However, the observed impacts of woody mortality on ecosystem‐scale energy and water budgets and the responses of surviving vegetation are highly variable among studies in water‐limited environments. A previous...

Modeling the carbon uptake process by plants provides the foundation for global vegetation models. We modified the Canopy Conductance Constrained Carbon Assimilation (4C-A) model, a multi-level assimilation model that utilizes sap-flux measurements, based on the stomatal optimization theory. A novel method of calculating optimal stomatal conductanc...

Carbon dioxide (CO2) exchange of tidal brackish wetlands and how they may be affected by restoration methods are largely unknown. The New Jersey Meadowlands, a tidal brackish estuary system, have had a long history of pollution, hydrological alterations, multiple restoration and mitigation treatments since the early 1970ies. To understand the effec...

Due to increased loss of wetland areas globally, restoration of wetlands has become common practice and is applied to increase wetland areas as well as improving ecological services of existing wetlands. Although the importance of wetlands in carbon sequestration has been recognized, the effects of restoration activities on CO2 release and uptake a...

The dispersal ability of plants is a major factor driving ecological responses to global change. In wind‐dispersed plant species, non‐random seed release in relation to wind speeds has been identified as a major determinant of dispersal distances. However, little information is available about the costs and benefits of non‐random abscission and the...

The transport of heavy particles in a medium that consists of fluid and solid phases such as stream gravel beds, cracked soils and wetlands is affected by processes such as attachment-detachment, gravity and drag, and by mixing processes that are induced by Taylor dispersion and mechanical dispersion. This paper addresses an additional dispersion m...

In addition to buffering plants from water stress during severe droughts, plant water storage (PWS) alters many features of the spatio‐temporal dynamics of water movement in the soil–plant system. How PWS impacts water dynamics and drought resilience is explored using a multi‐layer porous media model. The model numerically resolves soil–plant hydro...

The inadequacy of conventional gradient-diffusion in closure modeling of turbulent heat fluxes within the convective atmospheric boundary-layer is often alleviated by accounting for nonlocal transport effects, such as Deardorff's counter-gradient models, Wyngaard's transport asymmetry closures, or mass-flux parametrization. This concept of large-ed...

The inadequacy of conventional gradient-diffusion closure in modeling turbulent heat flux within the convective atmospheric boundary-layer is often alleviated by accounting for nonlocal transport. Such nonlocal effects are a manifestation of the inherent asymmetry in vertical transport in the convective boundary layer, which is in turn associated w...

The dispersion of heavy particles such as seeds within canopies is evaluated using Lagrangian stochastic trajectory models, laboratory, and field experiments. Inclusion of turbulent kinetic energy dissipation rate intermittency is shown to increase long-distance dispersal (LDD) by contributing to the intermittent ejection of particles to regions of...

The inadequacy of conventional gradient-diffusion in modeling scalar fluxes within the convective atmospheric boundary-layer is often alleviated by accounting for nonlocal transport effects, such as Deardorff’s counter-gradient hypothesis, Wyngaard’s transport asymmetry closures, or mass-flux parametrizations. Such nonlocal effects are a manifestat...

While few dispute the significance of within-canopy sources or sinks of reactive gaseous and particulate compounds, their estimation continues to be the subject of active research and debate. Reactive species undergo turbulent dispersion within an inhomogeneous flow field, and may be subjected to chemical, biological and/or physical deposition, emi...

Canopy flow models are often dedicated to ideal, infinite, homogenous systems. However, real canopy systems have physical boundaries, where the flow enters and leaves patches of vegetation, generating a complex pressure field and velocity variations.Here we focus our study on the canopy entry region by examining the terms involved in the double (sp...

A multi-layered flux footprint model is developed for a canopy situated within a protected environment such as a screenhouse. The model accounts for the vertically distributed sources and sinks within the canopy as well as modifications introduced by the screen on the flow field and micro-environment. The effect of the screen on fetch as a function...

In recent years, assessing the spatial representativeness of measured turbulent fluxes of carbon dioxide and water vapor within forests and crops (especially in protected environments) is drawing increased attention. This problem is analogous to deriving explicit relations between measured scalar turbulent fluxes and ecosystem sources or sinks. Suc...

An extended Lagrangian stochastic dispersion model that includes time variations of the turbulent kinetic energy dissipation rate is proposed. The instantaneous dissipation rate is described by a log-normal distribution to account for rare and intense bursts of dissipation occurring over short durations. This behaviour of the instantaneous dissipat...

Despite its importance, the problem of transfer phenomena at the interface between porous domains and homogeneous free flows found no complete general solution. In this study we contribute to the solution of the problem by studying the effect of a gradual geometrical change at the interface. Such a geometrical change is common to all cases, dependi...

A new approach for solving the laminar flow problem above a porous medium is presented here, using an apparent interface for which both superficial velocity and intrinsic shear stress are continuous. The derivation of this approach is based on a detailed investigation of the Ochoa-Tapia and Whitaker (Int. J. Heat Mass Transfer 38:2635–2646, 1995a)...