MY SIRR: Minimalist agro-hydrological model for Sustainable IRRigation management—Soil moisture and crop dynamics

The paper introduces a minimalist water-driven crop model for sustainable irrigation management using an eco-hydrological approach. Such model, called MY SIRR, uses a relatively small number of parameters and attempts to balance simplicity, accuracy, and robustness. MY SIRR is a quantitative tool to assess water requirements and agricultural production across different climates, soil types, crops, and irrigation strategies. The MY SIRR source code is published under copyleft license. The FOSS approach could lower the financial barriers of smallholders, especially in developing countries, in the utilization of tools for better decision-making on the strategies for short- and long-term water resource management.

How to cite: Albano, R., S. Manfreda, G. Celano, MYSIRR: Minimalist agro-hYdrological model for Sustainable IRRigation management – soil moisture and crop dynamicsSoftwareX, 6, 107–117, (doi: 10.1016/j.softx.2017.04.00), 2017. [pdf]

An ecohydrological framework to explain shifts in vegetation organization across climatological gradients

Spatial patterns found in vegetated ecosystems exhibit different degrees of organization in stand density that can be interpreted as an indicator of ecosystem health. In semiarid environments, it is possible to observe transitions from over-dispersed individuals (e.g., an ordered lattice) to under-dispersed individuals (e.g., clumped points). These configurations correspond to different strategies of adaptation or optimization, whose understanding may help to predict some of the consequences of environmental changes for both ecosystem services and water resources. For this reason, we have developed a theoretical framework that characterizes the dispersion of individuals through a generalized double Poisson distribution and estimates the landscape-wide statistics using a soil moisture model accounting for tree canopies and root systems overlapping. Considering both the shading effect (light interception) of the canopies and the partitioning of water fluxes due to the presence of multiple individual root systems in one point, the optimum spacing between individuals at a given stand density is determined. This framework allows identifying the climatic boundaries for different landscape patterns in terms of optimal water use and stress. This simple scheme explains well the observed patterns of vegetation in arid and semiarid ecosystems.

How to cite: Manfreda, S., K. K. Caylor, S. Good, An Ecohydrological framework to explain shifts in vegetation organization across climatological gradientsEcohydrology, 10(3), 1-14, (doi: 10.1002/eco.1809), 2017. [pdf]

On the Vulnerability of Water Limited Ecosystems to Climate Change

Society is facing growing environmental problems that require new research efforts to understand the way ecosystems operate and survive, and their mutual relationships with the hydrologic cycle. In this respect, ecohydrology suggests a renewed interdisciplinary approach that aims to provide a better comprehension of the effects of climatic changes on terrestrial ecosystems. With this aim, a coupled hydrological/ecological model is adopted to describe simultaneously vegetation pattern evolution and hydrological water budget at the basin scale using as test site the Upper Rio Salado basin (Sevilleta, NM, USA). The hydrological analyses have been carried out using a recently formulated framework for the water balance at the daily level linked with a spatial model for the description of the spatial organization of vegetation. This enables quantitatively assessing the effects on soil water
availability on future climatic scenarios. Results highlighted that the relationship between climatic forcing (water availability) and vegetation patterns is strongly non-linear. This implies, under some specific conditions which depend on the ecosystem characteristics, small changes in climatic conditions may produce significant transformation of the vegetation patterns.

How to cite: Manfreda, S., K.K. Caylor, On The Vulnerability of Water Limited Ecosystems to Climate ChangeWater, 5(2), 819-833; (doi:10.3390/w5020819), 2013. [pdf]

Modelling Vegetation Patterns in Semiarid Environments

The aim of this work is to deepen our understanding on the mutual relationship between climate, vegetation and soil water budget within an ecohydrological framework. To this end a coupled hydrological/ecological model is adopted to describe simultaneously soil water budget and vegetation pattern evolution in a semiarid river basin in New Mexico (USA). This basin represents an ideal area to study the properties of water-controlled ecosystems. Analyses have been carried out using a recently formulated framework for the water balance at the daily level linked with a vegetation model for the description of the spatial organization of vegetation. Using this approach, we identified the dynamic water stress of vegetation during the growing season, taking into account effects of morphology on the spatial distribution of solar radiation and the initial soil moisture condition at the beginning of the growing season. Several different variants of the vegetation model have been tested with the aim to identify the main drivers for the spatial organization of the vegetation. Results clearly show that the observed vegetation patterns emerge from the minimization of water stress and the maximization of water use.

How to cite: Manfreda, S., T. Pizzolla, K.K. Caylor, Modeling Vegetation Patterns in Semiarid Environment, Procedia Environmental Science, 19, 168-177, (doi: 10.1016/j.proenv.2013.06.019) 2013. [pdf]

Preface Coupled ecological–hydrological processes

The papers in this issue represent a selection of the presentations made at the session entitled “Climate-soil and vegetation interactions in ecological–hydrological processes” of the European Geophysical Union General Assembly. The special issue “Coupled Ecological–Hydrological Processes” focuses on different aspects of Ecohydrology that can be summarized in the following topics: soil moisture dynamics, soil–plant interactions, vegetation modelling and effects of climate change on natural ecosystems.

How to cite: Salvatore Manfreda, Keith Smettem, Vito Iacobellis, Nicola Montaldo and Murugesu Sivapalan, Preface Coupled ecological –hydrological processes, ECOHYDROLOGY, 3, Pages 131–132 (doi: 10.1002/eco.131), 2010. [pdf]

On the importance of accurate depiction of infiltration processes on modelled soil moisture and vegetation water stress

The description of soil moisture dynamics is a challenging problem for the hydrological community, as it is governed by complex interactions between climate, soil and vegetation. Recent research has achieved significant advances in the description of temporal dynamics of soil water balance through the use of a stochastic differential equation proposed by Laio et al. (2001). The assumptions of the Laio et al. model simplify the mathematical form of the soil water loss functions and the infiltration process. In particular, runoff occurs only for saturation excess, the probability distribution function (PDF) of which is well represented by a simple expression, but the model does not consider the limited infiltration capacity of soil. In the present work, we extend the soil moisture model to include limitations on soil infiltration capacity with the aim of understanding the impact of varying infiltration processes on the soil water balance and vegetation stress. A comparison between the two models (the original version and the modified one) is carried out via numerical simulations. The limited infiltration capacity influences the soil moisture PDF by reducing its mean and variance. Major changes in the PDFs are found for climates characterized by storms of short duration and high rainfall intensity, as well as in humid climates and in cases where soils have moderate permeability (e.g. loam and clay soils). In the case of limited infiltration capacity, modifications to the dynamics of soil moisture generally lead to higher amounts of vegetation water stress. An investigation of the role of soil texture on vegetation water stress demonstrates that loam soil provides the most favorable condition for plant-growth under arid and semi-arid conditions, while vegetation may benefit from the presence of more permeable soils (e.g. loamy sand) in humid climates.

How to cite: Manfreda, S., T.M. Scanlon, K.K. Caylor, On the importance of accurate depiction of infiltration processes on modelled soil moisture and vegetation water stressEcohydrology, 3, 155-165, (doi: 10.1002/eco.79), 2010. [pdf]

Ecohydrology: A new Interdisciplinary Approach to Investigate on Climate – Soil – Vegetation Interactions

Society is facing growing environmental problems that require new research efforts to understand of the way that ecosystems operate and survive and their mutual relationships with the hydrologic cycle. This is fundamental to advance predictive models used by researchers, industry, and environmental managers. In this frame, Ecohydrology faces this task with the aim to provide improved forecasting and mitigation of flood and drought risk, better understanding of implications of land use changes on terrestrial ecosystems (such as deforestation or desertification), improved weather and climate predictions, better comprehension of climatic changes effects on terrestrial ecosystems. The scope of the present paper is to address the most challenging questions of ecohydrology providing a review of some of the most recent results in this emerging field.

How to cite: Salvatore Manfreda, Ecohydrology: A new Interdisciplinary Approach to Investigate on Climate – Soil – Vegetation Interactions, Annals of Arid Zone, Volume 48, Number 3 e 4, September and December, Pages 219-228, ISSN 0570-1791, 2009. 

The Olive Tree: a Paradigm for Drought Tolerance in Mediterranean Climates

Olive trees (Olea europaea L.) are commonly grown in the Mediterranean basin where prolonged droughts may occur during the vegetative period. This species has developed a series of physiological mechanisms, that can be observed in several plants of the Mediterranean macchia, to tolerate drought stress and grow under adverse climatic conditions. These mechanisms have been investigated through an experimental campaign carried out over both irrigated and drought-stressed plants in order to comprehend the plant response under stressed conditions and its ability to recover. Experimental results show that olive plants subjected to water deficit lower the water content and water potentials of their tissues, establishing a particularly high potential gradient between leaves and roots, and stop canopy growth but not photosynthetic activity and transpiration. This allows the continuous production of assimilates as well as their accumulation in the various plant parts, so creating a higher root/leaf ratio if compared to well-watered plants. Active and passive osmotic adjustment due to the accumulation of carbohydrates (in particular mannitol and glucose), proline and other osmolytes have key roles in maintaining cell turgor and leaf activities. At severe drought-stress levels, the non-stomatal component of photosynthesis is inhibited and a light-dependent inactivation of the photosystem II occurs. Finally, the activities of some antioxidant enzymes involved in the scavenging of activated oxygen species and in other biochemical pathways increase during a period of drought. The present paper provides an overview of the driving mechanisms adopted by olive trees to face drought stress with the aim of better understanding plant-soil interactions.

How to cite: Sofo, A., S. Manfreda, B. Dichio, M. Fiorentino, C. Xiloyannis, The Olive Tree: a Paradigm for Drought Tolerance in Mediterranean Climates, Hydrology and Earth System Sciences, 12, 293-301, (doi:10.5194/hess-12-293-2008), 2008. [pdf]

Reply to comment by S. Nadarajah on ‘‘Space-time modeling of soil moisture: Stochastic rainfall forcing with heterogeneous vegetation’’

The comment by Nadarajah [2007] focuses on the spatial correlation function of the rainfall forcing adopted in the theoretical analysis of the soil water balance addressed by Isham et al. [2005] and Rodrıguez-Iturbe et al. [2006].

How to cite: Manfreda, S., D.R. Cox, V. Isham, A. Porporato, I. Rodríguez-Iturbe, Reply to the Comment by S. Nadarajah on “Space-time modeling of soil moisture: Stochastic rainfall forcing with heterogeneous vegetation”Water Resources Research, 43, W10602, (doi:10.1029/2007WR006378), 2007. [pdf]

The olive tree: a paradigm for drought tolerance in Mediterranean climates

Olive tree (Olea europaea L.) is commonly grown in the Mediterranean basin where prolonged droughts may occur during the vegetative period. This species has developed a series of physiological mechanisms to tolerate drought stress and grow under adverse climatic conditions that can be observed in numerous plants of the Mediterranean macchia. These mechanisms have been investigated through an experimental campaign carried out over both irrigated and drought-stressed plants in order to comprehend the plant response under stressed conditions and its ability to recover. Experimental results show that olive plants subjected to water deficit lower the water content and water potentials of their tissues, establishing a particularly high potential gradient between leaves and roots, and stop canopy growth but not photosynthetic activity and transpiration. This allows the continuous production of assimilates as well as their accumulation in the various plant parts, so creating a higher root/leaf ratio if compared to well-watered plants. Active and passive osmotic adjustment due to the accumulation of sugars (in particular mannitol and glucose), proline and other osmolytes has a key role in maintaining cell turgor and leaf activities. At severe drought-stress levels, the non-stomatal component of photosynthesis is inhibited and a light-dependent inactivation of the photosystem II occurs. Finally, the activities of some antioxidant enzymes involved in the scavenging of activated oxygen species and in other biochemical pathways, increase during a period of drought. The present paper provides an overview of the driving mechanisms adopted by olive trees to face drought stress with the aim of better understand plant-soil interactions.

How to cite: A. Sofo, S. Manfreda, B. Dichio, M. Fiorentino and C. Xiloyannis, The olive tree: a paradigm for drought tolerance in Mediterranean climates, Hydrology and Earth System Sciences Discussions, 4, Pages 2811–2835, 2007. [pdf]