For me ecohydrology is the framework that would allow us to explore the comprehensive soil-plant-water relationship. The primary aim is to understand soil carbon sequestration capacity in relation to climate change and other anthropogenic perturbations.
What are your undergraduate and graduate degrees in?
I pursued my engineering studies from Bengal Engineering and Science University (BE) in India and my MS from University of Kentucky. However, I always wanted to pursue my studies in Environmental Science and my MS thesis explored acid drainage treatment using surface treatment technology. I was lucky to pursue my doctoral studies at State University of New York, Buffalo, under the guidance of Dr D.S. Mackay. Essentially, I identify myself as a carbon cycle and environmental data scientist.
How did you arrive at working in/thinking about ecohydrology?
My research in ecohydrology started with simulating eddycovariance-derived carbon and water flux across the cold semi-arid sagebrush ecosystem in Wyoming using the process-based ecosystem model TREES. The data was provided by Dr Elise Pendall and Dr Brent Ewers from University of Wyoming from their sagebrush-steppe ecosystem research site. While simulating carbon and water fluxes, I designed geostatistical and climate change manipulation experiment to explore different hypothesis about model failure in simulating both the fluxes. These experiments were conducted by me at Saratoga, Wyoming.
These studies set up the foundation for me explore the linkage between different exogeneous and endogenous drivers that simulate greenhouse gas emission (soil respiration, methane) across managed and natural coastal wetland ecosystem in North Carolina.
Overall, I would state that quantitative analysis of greenhouse gas emission has been a key theme of my research for the last 15 years. To that end, I have incorporated extensive field work along with ecosystem models and different statistical techniques (parametric and non-parametric) to analyze control of vegetation activity on greenhouse gas emission at different spatial (leaf, plant, landscape) and temporal (sub-daily, diurnal, diurnal, synoptic, monthly) resolution.
What do you see as an important emerging area of ecohydrology?
Identifying causality in complex ecohydrological processes. Simply put, nonlinear dynamics are ubiquitous across ecohydrological systems.
For example, soil respiration and wetland methane emission are important metrics of ecosystem metabolism. Both these processes are multivariate, multidimensional and non-linear. Ideally, ecosystem manipulation experiment can help us to explore causation. However, that may not always be the case.
My two recent papers (Mitra et al., 2019; Mitra et al., 2020), under the supervision of Dr Asko Noormets (Texas A & M University) and Dr John King (North Carolina State University) explored causality within a spectral modeling and information theory framework. The study explored how the different drivers of soil respiration and wetland methane emission are sometime positively and negatively coupled with different biotic and abiotic drivers at different temporal resolution across the coastal wetland ecosystem in North Carolina. Radically different control regimes for soil respiration and methane, depending on time and temporal scale (diurnal, synoptic etc) is characteristics of complex non-linear systems.
Variables which may be positively coupled can become decoupled during certain time periods. This definitely creates an issue while fitting functional relationship to observed data. One must also exercise caution in differentiating between correlation and causation as the former remains ingrained in our heuristic thoughts. Lack of correlation does not necessarily imply lack of causation.
Overall, causal analysis point highlights the need to develop “spectrally-truthful” ecosystem models that can potentially reduce the uncertainty with estimation of greenhouse emission across different ecosystems.
Do you have a favorite ecohydrology paper? Describe/explain.
While there are many, I would likely refer to Dr Gabriel Katul’s paper as highlighted below:
Katul, G., C.-T. Lai, K.V.R. Schäfer, B. Vidakovic, J.D. Albertson, D.S. Ellsworth and R. Oren. 2001. Multiscale analysis of vegetation surface fluxes: from seconds to years. Adv. Water Resour. 24: 1119-1132.
I consider this paper to be the fundamental reference for the application of wavelet techniques in ecosystem science. Subsequent 20 years of study by different researchers on control on eddy fluxes by different physical and biological processes is heavily inspired by this paper.
What do you do for fun (apart from ecohydrology)?
Simply chatting with my mother, my friends, going out for occasional swim, playing soccer and cricket, watching movies and reading fiction literatures. Jane Austen and Rabindranath Tagore are my favorite novelists and William Wordsworth remain my favorite poet.