URLanized spatial patterns of vegetation are frequent in water-limited regions and have been suggested as important ecosystem health indicators . However, the mechanisms underlying their formation remain unclear. It has been hypothesized that patterns could emerge from a water-mediated scale-dependent feedback (SDF), whereby interactions favoring plant growth dominate at short distances while growth-inhibitory interactions dominate in the long-range. As precipitation declines, this framework predicts a sequential change from gapped to labyrinthine to spotted spatial patterns. However, we know little about how net plant-to-plant interactions may shift from positive to negative as a function of inter-individual distance, and in the absence of strong empirical support, the relevance of  SDF for vegetation pattern formation remains disputed. Alternative theories show that the same sequence of patterns could emerge when interactions between plants are always inhibitory if their intensity decays sharply enough with inter-individual distance . Although these alternative hypotheses lead to visually indistinguishable spatial distributions of plants, they predict different ecosystem-level consequences for the patterns, thus limiting their potential use as ecosystem-state indicators . Therefore, to make reliable ecological predictions , models need to accurately capture the mechanisms at play in the systems of interest. Here, we review existing theories for vegetation URLanization and their conflicting ecosystem-level predictions . We discuss ways to reconcile these predictions . We focus on the mechanistic differences among models, which can provide valuable information to help researchers decide which model to use for a particular system and /or whether it requires modification .
URLanized spatial patterns of vegetation are frequent in water-limited regions and have been suggested as important indicators of ecosystem health . However, the mechanisms underlying their emergence remain unclear. Some theories hypothesize that patterns could result from a scale-dependent feedback (SDF), whereby interactions favoring plant growth dominate at short distances and growth-inhibitory interactions dominate in the long range. However, we know little about how net plant-to-plant interactions may change sign with inter-individual distance, and in the absence of strong empirical support, the relevance of this SDF for vegetation pattern formation remains disputed. These theories predict a sequential change in pattern shape from gapped to labyrinthine to spotted spatial patterns as precipitation declines. Nonetheless, alternative theories show that the same sequence of patterns could emerge even if net interactions between plants were always inhibitory (purely competitive feedbacks, PCF) . Although these alternative hypotheses lead to visually indistinguishable patterns they predict very different desertification dynamics following the spotted pattern. Moreover, vegetation interaction with other ecosystem components can introduce additional spatio-temporal scales that reshape both the patterns and the desertification dynamics . Therefore, to make reliable ecological predictions for a focal ecosystem, it is crucial that models accurately capture the mechanisms at play in the system of interest. Here, we review existing theories for vegetation URLanization and their conflicting predictions about desertification dynamics. We further discuss possible ways for reconciling these predictions and potential empirical tests via manipulative experiments to improve our understanding of how vegetation URLanizes and better predict the fate of the ecosystems where they form .
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ecosystem health indicators
indicators of ecosystem health
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formation
emergence
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It has been hypothesized
Some theories hypothesize
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emerge from a water-mediated
result from a
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while
and
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long-range. As precipitation declines, this framework predicts a sequential change from gapped to labyrinthine to spotted spatial patterns.
long range.
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shift from positive to negative as a function of
change sign with
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this
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Alternative theories
These theories predict a sequential change in pattern shape from gapped to labyrinthine to spotted spatial patterns as precipitation declines. Nonetheless, alternative theories
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when
even if net
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are always inhibitory if their intensity decays sharply enough with inter-individual distance
were always inhibitory (purely competitive feedbacks, PCF)
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spatial distributions of plants, they predict different ecosystem-level consequences for the patterns, thus limiting their potential use as ecosystem-state indicators
patterns they predict very different desertification dynamics following the spotted pattern. Moreover, vegetation interaction with other ecosystem components can introduce additional spatio-temporal scales that reshape both the patterns and the desertification dynamics
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, models need to
for a focal ecosystem, it is crucial that models
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systems
system
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ecosystem-level predictions . We discuss ways to reconcile these predictions . We focus on the mechanistic differences among models, which can provide valuable information to help researchers decide which model to use for a particular system and /or whether it requires modification
predictions about desertification dynamics. We further discuss possible ways for reconciling these predictions and potential empirical tests via manipulative experiments to improve our understanding of how vegetation URLanizes and better predict the fate of the ecosystems where they form