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Assessing landscape structure and pattern fragmentation in semiarid ecosystems using patch-size distributions

Moreno-de las Heras, M.; Saco, P.M.; Willgoose, G.R.; Tongway, D.J.

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M. Moreno-de las Heras

P.M. Saco

G.R. Willgoose

D.J. Tongway


Spatial vegetation patterns are recognized as sources of valuable information that can be used to infer the state and functionality of semiarid ecosystems, particularly in the context of both climate and land use change. Recent studies have suggested that the patch‐size distribution of vegetation in drylands can be described using power‐law metrics, and that these scale‐free distributions deviate from power‐law linearity with characteristic scale lengths under the effects of increasing aridity or human disturbance, providing an early sign of desertification. These findings have been questioned by several modeling approaches, which have identified the presence of characteristic scale lengths on the patch‐size distribution of semiarid periodic landscapes. We analyze the relationship between fragmentation of vegetation patterns and their patch‐size distributions in semiarid landscapes showing different degree of periodicity (i.e., banding). Our assessment is based on the study of vegetation patterns derived from remote sensing in a series of semiarid Australian Mulga shrublands subjected to different disturbance levels. We use the patch‐size probability density and cumulative probability distribution functions from both nondirectional and downslope analyses of the vegetation patterns. Our results indicate that the shape of the patch‐size distribution of vegetation changes with the methodology of analysis applied and specific landscape traits, breaking the universal applicability of the power‐law metrics. Characteristic scale lengths are detected in (quasi) periodic banded ecosystems when the methodology of analysis accounts for critical landscape anisotropies, using downslope transects in the direction of flow paths. In addition, a common signal of fragmentation is observed: the largest vegetation patches become increasingly less abundant under the effects of disturbance. This effect also explains deviations from power‐law behavior in disturbed vegetation which originally showed scale‐free patterns. Overall, our results emphasize the complexity of structure assessment in dryland ecosystems, while recognizing the usefulness of the patch‐size distribution of vegetation for monitoring semiarid ecosystems, especially through the cumulative probability distributions, which showed high sensitivity to fragmentation of the vegetation patterns. We suggest that preserving large vegetation patches is a critical task for the maintenance of the ecosystem structure and functionality.


Moreno-de las Heras, M., Saco, P., Willgoose, G., & Tongway, D. (2011). Assessing landscape structure and pattern fragmentation in semiarid ecosystems using patch-size distributions. Ecological Applications, 21(7), 2793-2805.

Journal Article Type Article
Acceptance Date Mar 8, 2011
Online Publication Date Oct 1, 2011
Publication Date Oct 1, 2011
Deposit Date Nov 28, 2013
Publicly Available Date Jun 1, 2018
Journal Ecological applications
Print ISSN 1051-0761
Publisher Ecological Society of America
Peer Reviewed Peer Reviewed
Volume 21
Issue 7
Pages 2793-2805


Published Journal Article (2.7 Mb)

Copyright Statement
© 2011 by the Ecological Society of America

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