James B. Grace 2017 <div class="pl20 mq875-pl0 serif"><p>Society has an increasing awareness that there are finite limits to what we can expect the planet to absorb and still provide goods and services at current rates^{<a id="ref-link-section-1" title="Millennium Ecosystem Assessment Ecosystems and Human Well-being: Desertification Synthesis (World Resources Institute, 2005)." href="http://www.nature.com/articles/s41559-016-0047#ref1" data-track="click" data-track-source="reference-anchor" data-track-dest="link:1" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref1">1</a>}. Both historical reconstructions and contemporary events continue to remind us that ecological regime changes are often abrupt rather than gradual. This reality motivates researchers who seek to discover leading indicators for impending ecosystem change. Berdugo <i>et al</i>.^{<a id="ref-link-section-2" title="Berdugo, M., Kéfi, S., Soliveres, S. &amp; Maestre, F. T. Nat. Ecol. Evol. 1, 0003 (2017)." href="http://www.nature.com/articles/s41559-016-0047#ref2" data-track="click" data-track-source="reference-anchor" data-track-dest="link:2" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref2">2</a>} report an important advance in our ability to anticipate the conversion of arid lands from self-organized, self-maintaining and productive ecosystems, to a state characterized by disorganization and low functionality. Such conversions have important implications for our understanding of ‘desertification’ — which is a shift from arid to desert-like conditions.</p></div><div class="pl20 mq875-pl0 serif"><p>Theoretical studies have suggested that patterns in the patchiness of vegetation might indicate how close a system is to making an abrupt change to desert-like conditions^{<a id="ref-link-section-3" title="Rietkerk, M., Dekker, S. C., de Ruiter, P. C. &amp; van de Koppel, J. Science 305, 1926–1929 (2004)." href="http://www.nature.com/articles/s41559-016-0047#ref3" data-track="click" data-track-source="reference-anchor" data-track-dest="link:3" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref3">3</a>,<a id="ref-link-section-4" title="Kéfi, S. et al. Nature 449, 213–217 (2007)." href="http://www.nature.com/articles/s41559-016-0047#ref4" data-track="click" data-track-source="reference-anchor" data-track-dest="link:4" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref4">4</a>,<a id="ref-link-section-5" title="Kéfi, S. et al. Ecol. Lett. 14, 29–35 (2011)." href="http://www.nature.com/articles/s41559-016-0047#ref5" data-track="click" data-track-source="reference-anchor" data-track-dest="link:5" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref5">5</a>}. Empirical studies, however, have tended to show instead that simply the total cover of vegetation, rather than its arrangement, often foretells the state of the system^{<a id="ref-link-section-6" title="Kéfi, S. et al. Nature 449, 213–217 (2007)." href="http://www.nature.com/articles/s41559-016-0047#ref4" data-track="click" data-track-source="reference-anchor" data-track-dest="link:4" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref4">4</a>,<a id="ref-link-section-7" title="Kéfi, S. et al. Ecol. Lett. 14, 29–35 (2011)." href="http://www.nature.com/articles/s41559-016-0047#ref5" data-track="click" data-track-source="reference-anchor" data-track-dest="link:5" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref5">5</a>,<a id="ref-link-section-8" title="Maestre, F. T., Escudero, A. Ecology 90, 1729–1735 (2009)." href="http://www.nature.com/articles/s41559-016-0047#ref6" data-track="click" data-track-source="reference-anchor" data-track-dest="link:6" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref6">6</a>,<a id="ref-link-section-9" title="Bestelmeyer, B. T., Duniway, M. C., James, D. K., Burkett, L. M. &amp; Havstad, K. M. Ecol. Lett. 16, 339–345 (2013)." href="http://www.nature.com/articles/s41559-016-0047#ref7" data-track="click" data-track-source="reference-anchor" data-track-dest="link:7" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref7">7</a>,<a id="ref-link-section-10" title="Moreno-de las Heras, M., Saco, P. M., Willgoose, G. R. &amp; Tongway, D. J. Ecol. Appl. 21, 2793–2805 (2011)." href="http://www.nature.com/articles/s41559-016-0047#ref8" data-track="click" data-track-source="reference-anchor" data-track-dest="link:8" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref8">8</a>,<a id="ref-link-section-11" title="Lin, Y., Han, G., Zhao, M. &amp; Chang, S. X. Landscape Ecol. 25, 1519–1527 (2010)." href="http://www.nature.com/articles/s41559-016-0047#ref9" data-track="click" data-track-source="reference-anchor" data-track-dest="link:9" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref9">9</a>}. Berdugo <i>et al</i>.^{<a id="ref-link-section-12" title="Berdugo, M., Kéfi, S., Soliveres, S. &amp; Maestre, F. T. Nat. Ecol. Evol. 1, 0003 (2017)." href="http://www.nature.com/articles/s41559-016-0047#ref2" data-track="click" data-track-source="reference-anchor" data-track-dest="link:2" data-mce-href="http://www.nature.com/articles/s41559-016-0047#ref2">2</a>} combine these competing ideas into one integrated perspective. They show how major environmental drivers, such as aridity, influence both vegetation cover and patchiness, as well as where self-organizing, stabilizing forces in the vegetation are likely to be found.</p></div> application/pdf 10.1038/s41559-016-0047 en Nature Signals of impending change article