scholarly journals An ecohydrological approach to predicting hillslope-scale vegetation patterns in dryland ecosystems

2012 ◽  
Vol 48 (1) ◽  
Author(s):  
Trenton E. Franz ◽  
Kelly K. Caylor ◽  
Elizabeth G. King ◽  
Jan M. Nordbotten ◽  
Michael A. Celia ◽  
...  
Keyword(s):  
Vegetation Patterns ◽  
Dryland Ecosystems ◽  
Hillslope Scale

scholarly journals A mechanistic description of the formation and evolution of vegetation patterns

2013 ◽  
Vol 17 (1) ◽  
pp. 63-84 ◽  
Author(s):  
R. Foti ◽  
J. A. Ramírez
Keyword(s):  
Soil Moisture ◽  
Pattern Formation ◽  
Vegetation Pattern ◽  
Climatic Conditions ◽  
Vegetation Patterns ◽  
Self Organized ◽  
Physically Based ◽  
Density Surface ◽  
Formation And Evolution ◽  
Hillslope Scale

Abstract. Vegetation patterns are a common and well-defined characteristic of many landscapes. In this paper we explore some of the physical mechanisms responsible for the establishment of self-organized, non-random vegetation patterns that arise at the hillslope scale in many areas of the world, especially in arid and semi-arid regions. In doing so, we provide a fundamental mechanistic understanding of the dynamics of vegetation pattern formation and development. Reciprocal effects of vegetation on the hillslope thermodynamics, runoff production and run-on infiltration, root density, surface albedo and soil moisture content are analyzed. In particular, we: (1) present a physically based mechanistic description of processes leading to vegetation pattern formation; (2) quantify the relative impact of each process on pattern formation; and (3) describe the relationships between vegetation patterns and the climatic, hydraulic and topographic characteristics of the system. We validate the model by comparing simulations with observed natural patterns in the areas of Niger near Niamey and Somalia near Garoowe. Our analyses suggest that the phenomenon of pattern formation is primarily driven by run-on infiltration and mechanisms of facilitation/inhibition among adjacent vegetation groups, mediated by vegetation effects on soil properties and controls on soil moisture and albedo. Nonetheless, even in presence of those mechanisms, patterns arise only when the climatic conditions, particularly annual precipitation and net radiation, are favorable.

scholarly journals Multistability of model and real dryland ecosystems through spatial self-organization

2018 ◽  
Vol 115 (44) ◽  
pp. 11256-11261 ◽  
Author(s):  
Robbin Bastiaansen ◽  
Olfa Jaïbi ◽  
Vincent Deblauwe ◽  
Maarten B. Eppinga ◽  
Koen Siteur ◽  
...  
Keyword(s):  
Early Warning Systems ◽  
Aerial Photographs ◽  
Self Organization ◽  
Optical Data ◽  
Small Scale ◽  
Vegetation Patterns ◽  
Total Biomass ◽  
Contrast Model ◽  
Model Predictions ◽  
Dryland Ecosystems

Spatial self-organization of dryland vegetation constitutes one of the most promising indicators for an ecosystem’s proximity to desertification. This insight is based on studies of reaction–diffusion models that reproduce visual characteristics of vegetation patterns observed on aerial photographs. However, until now, the development of reliable early warning systems has been hampered by the lack of more in-depth comparisons between model predictions and real ecosystem patterns. In this paper, we combined topographical data, (remotely sensed) optical data, and in situ biomass measurements from two sites in Somalia to generate a multilevel description of dryland vegetation patterns. We performed an in-depth comparison between these observed vegetation pattern characteristics and predictions made by the extended-Klausmeier model for dryland vegetation patterning. Consistent with model predictions, we found that for a given topography, there is multistability of ecosystem states with different pattern wavenumbers. Furthermore, observations corroborated model predictions regarding the relationships between pattern wavenumber, total biomass, and maximum biomass. In contrast, model predictions regarding the role of slope angles were not corroborated by the empirical data, suggesting that inclusion of small-scale topographical heterogeneity is a promising avenue for future model development. Our findings suggest that patterned dryland ecosystems may be more resilient to environmental change than previously anticipated, but this enhanced resilience crucially depends on the adaptive capacity of vegetation patterns.

scholarly journals Termite mounds can increase the robustness of dryland ecosystems to climatic change

Science ◽  
2015 ◽  
Vol 347 (6222) ◽  
pp. 651-655 ◽  
Author(s):  
Juan A. Bonachela ◽  
Robert M. Pringle ◽  
Efrat Sheffer ◽  
Tyler C. Coverdale ◽  
Jennifer A. Guyton ◽  
...  
Keyword(s):  
Arid Ecosystems ◽  
Coarse Grained ◽  
Vegetation Patterns ◽  
Characteristic Sequence ◽  
Termite Mounds ◽  
Sparse Vegetation ◽  
Self Organized ◽  
Dryland Ecosystems ◽  
Substrate Heterogeneity ◽  
Catastrophic Shifts

Self-organized spatial vegetation patterning is widespread and has been described using models of scale-dependent feedback between plants and water on homogeneous substrates. As rainfall decreases, these models yield a characteristic sequence of patterns with increasingly sparse vegetation, followed by sudden collapse to desert. Thus, the final, spot-like pattern may provide early warning for such catastrophic shifts. In many arid ecosystems, however, termite nests impart substrate heterogeneity by altering soil properties, thereby enhancing plant growth. We show that termite-induced heterogeneity interacts with scale-dependent feedbacks to produce vegetation patterns at different spatial grains. Although the coarse-grained patterning resembles that created by scale-dependent feedback alone, it does not indicate imminent desertification. Rather, mound-field landscapes are more robust to aridity, suggesting that termites may help stabilize ecosystems under global change.

scholarly journals A morphometric analysis of vegetation patterns in dryland ecosystems

2017 ◽  
Vol 4 (2) ◽  
pp. 160443 ◽  
Author(s):  
Luke Mander ◽  
Stefan C. Dekker ◽  
Mao Li ◽  
Washington Mio ◽  
Surangi W. Punyasena ◽  
...  
Keyword(s):  
Spatial Patterns ◽  
Large Scale ◽  
Quantitative Methods ◽  
Pollen Grains ◽  
Vegetation Patterns ◽  
Bare Ground ◽  
Real World Data ◽  
Small Set ◽  
Dryland Ecosystems ◽  
Algorithmic Techniques

Vegetation in dryland ecosystems often forms remarkable spatial patterns. These range from regular bands of vegetation alternating with bare ground, to vegetated spots and labyrinths, to regular gaps of bare ground within an otherwise continuous expanse of vegetation. It has been suggested that spotted vegetation patterns could indicate that collapse into a bare ground state is imminent, and the morphology of spatial vegetation patterns, therefore, represents a potentially valuable source of information on the proximity of regime shifts in dryland ecosystems. In this paper, we have developed quantitative methods to characterize the morphology of spatial patterns in dryland vegetation. Our approach is based on algorithmic techniques that have been used to classify pollen grains on the basis of textural patterning, and involves constructing feature vectors to quantify the shapes formed by vegetation patterns. We have analysed images of patterned vegetation produced by a computational model and a small set of satellite images from South Kordofan (South Sudan), which illustrates that our methods are applicable to both simulated and real-world data. Our approach provides a means of quantifying patterns that are frequently described using qualitative terminology, and could be used to classify vegetation patterns in large-scale satellite surveys of dryland ecosystems.

scholarly journals Remotely-sensed slowing down in spatially patterned dryland ecosystems

2021 ◽  
Author(s):  
Michiel P Veldhuis ◽  
Ricardo Martinez-Garcia ◽  
Vincent Deblauwe ◽  
Vasilis Dakos
Keyword(s):  
Configuration Model ◽  
Vegetation Patterns ◽  
Rainfall Gradient ◽  
Slowing Down ◽  
In Situ Data ◽  
Critical Transitions ◽  
Non Linear ◽  
Dryland Ecosystems ◽  
Resilience Indicators ◽  
Future Work

Regular vegetation patterns have been predicted to indicate a system slowing down and possibly desertification of drylands. However, these predictions have not yet been observed in dryland vegetation due to the inherent logistic difficulty to gather longer-term in situ data. Here, we use recently developed methods using remote-sensing EVI time-series in combination with classified regular vegetation patterns along a rainfall gradient in Sudan to test these predictions. Overall, three temporal indicators (responsiveness, temporal autocorrelation, variance) show slowing down as vegetation patterns change from gaps to labyrinths to spots towards more arid conditions, confirming predictions. However, this transition exhibits non-linearities, specifically when patterns change configuration. Model simulations reveal that the transition between patterns temporarily slows down the system affecting the temporal indicators. These transient states when vegetation patterns reorganize thus affect the systems resilience indicators in a non-linear way. Our findings suggest that spatial self-organization of dryland vegetation is associated with critical slowing down, but this transition towards reduced resilience happens in a non-linear way. Future work should aim to better understand transient dynamics in regular vegetation patterns in dryland ecosystems, because long transients make regular vegetation patterns of limited use for management in anticipating critical transitions.

scholarly journals A mechanistic description of the formation and evolution of vegetation patterns

2012 ◽  
Vol 9 (7) ◽  
pp. 8737-8798
Author(s):  
R. Foti ◽  
J. A. Ramírez
Keyword(s):  
Soil Moisture ◽  
Pattern Formation ◽  
Vegetation Pattern ◽  
Climatic Conditions ◽  
Vegetation Patterns ◽  
Self Organized ◽  
Physically Based ◽  
Density Surface ◽  
Formation And Evolution ◽  
Hillslope Scale

Abstract. Vegetation patterns are a common and well-defined characteristic of many landscapes. In this paper we explore some of the physical mechanisms responsible for the establishment of self-organized, non-random vegetation patterns that arise at the hillslope scale in many areas of the world, especially in arid and semi-arid regions. In doing so, we provide a fundamental mechanistic understanding of the dynamics of vegetation pattern formation and development. Reciprocal effects of vegetation on the hillslope thermodynamics, runoff production and run-on infiltration, root density, surface albedo and soil moisture content are analyzed. In particular, we: (1) present a physically based mechanistic description of processes leading to vegetation pattern formation; (2) quantify the relative impact of each process on pattern formation; and (3) describe the relationships between vegetation patterns and the climatic, hydraulic and topographic characteristics of the system. We validate the model by comparing simulations with observed natural patterns in the areas of Niger near Niamey and Somalia near Garoowe. Our analyses suggest that the phenomenon of pattern formation is primarily driven by run-on infiltration and mechanisms of facilitation/inhibition among adjacent vegetation groups mediated by vegetation effects on soil properties and controls on soil moisture and albedo. Nonetheless, even in presence of those mechanisms, patterns arise only when the climatic conditions, particularly annual precipitation and net radiation, are favorable.

Spatial Distribution of Roots across Three Dryland Ecosystems and Plant Functional Types

2019 ◽  
Vol 79 (2) ◽  
pp. 159 ◽  
Author(s):  
Jessica G. Swindon ◽  
William K. Lauenroth ◽  
Daniel R. Schlaepfer ◽  
Ingrid C. Burke
Keyword(s):  
Spatial Distribution ◽  
Plant Functional Types ◽  
Functional Types ◽  
Dryland Ecosystems ◽  
Distribution Of Roots
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