Journal Article

Ecosystem resilience despite large-scale altered hydroclimatic conditions

McClaran, Mitchel P., Gunter, Stacey A., Eamus, Derek, McNab, W. Henry, Bresloff, Cynthia, Morgan, Jack A., Huxman, Travis E., Zhang, Yongguang, Peters, Debra P. C., Bosch, David D., Ponce-Campos, Guillermo E., Scalley, Tamara Heartsill, Moran, M. Susan, Buda, Anthony R., Montoya, Diane S., Huete, Alfredo, Kitchen, Stanley G., Sadler, E. John, Seyfried, Mark S., Starks, Patrick J.

2013

Overview

The resilience of a global sample of ecosystems to an increase in drought conditions is assessed, comparing data from the early twenty-first with the late twentieth century; results indicate a cross-ecosystem capacity for tolerating low precipitation and responding to high precipitation during recent warm drought and yet suggest a threshold to resilience with prolonged warm drought. Ecosystem resilience to water shortage and surfeit The early twenty-first century has seen a global increase in drought conditions. These authors describe the response of plant communities in a global sample of ecosystems to drought stress as a measure of ecosystem resilience, comparing data from the early twenty-first century with the late twentieth century. They find a common range of water-use efficiency values across timescales and locations, with the increases in dry years this century not yet compromising the ability to lower water-use efficiency in response to wetter years. This work will help provide an understanding of how vegetation production will respond to the altered hydroclimatic conditions predicted with climate change, important when making decisions about food production and resource management. Climate change is predicted to increase both drought frequency and duration, and when coupled with substantial warming, will establish a new hydroclimatological model for many regions 1 . Large-scale, warm droughts have recently occurred in North America, Africa, Europe, Amazonia and Australia, resulting in major effects on terrestrial ecosystems, carbon balance and food security 2 , 3 . Here we compare the functional response of above-ground net primary production to contrasting hydroclimatic periods in the late twentieth century (1975–1998), and drier, warmer conditions in the early twenty-first century (2000–2009) in the Northern and Southern Hemispheres. We find a common ecosystem water-use efficiency (WUE e : above-ground net primary production/evapotranspiration) across biomes ranging from grassland to forest that indicates an intrinsic system sensitivity to water availability across rainfall regimes, regardless of hydroclimatic conditions. We found higher WUE e in drier years that increased significantly with drought to a maximum WUE e across all biomes; and a minimum native state in wetter years that was common across hydroclimatic periods. This indicates biome-scale resilience to the interannual variability associated with the early twenty-first century drought—that is, the capacity to tolerate low, annual precipitation and to respond to subsequent periods of favourable water balance. These findings provide a conceptual model of ecosystem properties at the decadal scale applicable to the widespread altered hydroclimatic conditions that are predicted for later this century. Understanding the hydroclimatic threshold that will break down ecosystem resilience and alter maximum WUE e may allow us to predict land-surface consequences as large regions become more arid, starting with water-limited, low-productivity grasslands.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 631/158/2445 / 704/106/694/2739 / 704/158/2445 / aboveground biomass / Africa / Amazonia / Animal and plant ecology / Animal, plant and microbial ecology / Australia / Biological and medical sciences / carbon / Climate change / Climate Change - history / Climate Change - statistics & numerical data / Climatology. Bioclimatology. Climate change / Drought / Droughts - history / Droughts - statistics & numerical data / Earth, ocean, space / Ecosystem / Ecosystem resilience / Ecosystems / Efficiency / Environmental aspects / Europe / Evapotranspiration / Exact sciences and technology / Experiments / External geophysics / food security / Fundamental and applied biological sciences. Psychology / Grasslands / herbaceous plants / History, 20th Century / History, 21st Century / Humanities and Social Sciences / letter / Meteorology / multidisciplinary / North America / Observations / plant response / Plants - metabolism / Poaceae - metabolism / Primary production / primary productivity / Rain / Science / Synecology / Terrestrial ecosystems / Trees - metabolism / United States / Vegetation / Water - metabolism / Water availability / Water balance / Water Cycle / Water use / woody plants