Research
Interests
I’m interested in the interactions between soil, water and vegetation in drylands, in both natural and agricultural ecosystems. Our goal is to understand how the basic processes and feedbacks influence the ecosystem dynamics, and how this knowledge can be used to control those systems.
The common theme between my different research projects is land/ecosystem degradation caused by human activity.
Our research is based on “simple” mathematical models, that strive to capture the essential physical processes, while providing deep insight into the dynamics of the system. Some of the tools we use in the modeling of environmental questions come from dynamical systems, statistical physics and optimal control theory.
We are recruiting excellent students to our group! Here you can find some more detail on our current projects.
Projects
Soil salinization
Every week, the world loses an area greater than Manhattan to salt-related soil degradation. It is estimated that 20% of all irrigated lands are affected by salinity, with an even higher fraction of salt-degraded soils in arid and semiarid regions. Salt accumulation in the soil, usually induced by insufficient drainage and poor-quality irrigation water, imposes severe restrictions on food production.
Some of the questions we’d like to answer are: On what time scales the salinization process occurs, and what is the effect of a drier and more extreme climate on the salt buildup? What are the critical thresholds for (irreversible) soil degradation? How can we rehabilitate a degraded soil by making optimal use of the resources available? What role can treated wastewater have on dryland agriculture that is sustainable with respect to the ecosystem services?
Nutrient dynamics
Nitrogen management is of critical importance to food security and environmental sustainability. Because of artificial fertilizers, we have seen a sharp increase in agricultural production in the last century. However, the same nitrogen available to plant uptake, can polute the groundwater, streams and lakes, and be released as nitrous oxide, a potent greenhouse gas.
We would like to understand how the nonlinear dynamics of nitrogen and carbon cycling is influenced by the hydrological cycle. In particular, we would like to study the influence of random rainfall events and a changing climate in driving these cycles.
Tree water balance in a semiarid pine forest and rates of survival under global climate change
Longer droughts and temperature rise impose severe risks of widespread forest mortality. Drought-adapted trees in semiarid and arid ecosystems cope with water stress by regulating their transpiration rate, thus saving internal water content and avoiding runaway decline in water potential.
Our goal is to characterize how trees manage their water budget in order to increase survival probability under prolonged drought periods.
Our group will approach these objectives by modeling the soil-tree-atmosphere water transport to assess tree survival probability for current and future climate scenarios. A collaboration with an experimental group will provide us data from a research station in the Yatir forest, in the Negev desert (see map above).
Studying the fate of the Yatir forest gives us a window into the future, for it is expected that many ecosystems around the world will face increasing drought stress as a result of climate change.