Sensitivity of global terrestrial ecosystems to climate variability

• Published in: Nature (London) Vol. 531; no. 7593; pp. 229 - 232
• Main Authors: Seddon, Alistair W. R., Macias-Fauria, Marc, Long, Peter R., Benz, David, Willis, Kathy J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10-03-2016; Nature Publishing Group
• Subjects: 704/158/2165; 704/158/2445; 704/158/852; Acclimatization; Air temperature; Alpine regions; Americas; Anthropogenic factors; Arctic Regions; Asia; Australia; Boreal forests; Climate Change; Climate variability; Climatic changes; Cloud cover; Deciduous forests; Ecology; Ecosystem; Ecosystem resilience; Ecosystem services; Environmental aspects; Environmental impact analysis; Environmental Monitoring; Forests; Geographic Mapping; Human Activities; Humanities and Social Sciences; letter; Methods; Models, Theoretical; multidisciplinary; Plant Physiological Phenomena; Prairies; Precipitation; Rainforest; Rainforests; Science; Steppes; Studies; Taiga & tundra; Temperature; Terrestrial ecosystems; Time Factors; Trees; Tundra; Variables; Vegetation; Water - analysis; Water availability; Americas; Australia; Arctic Regions; Asia; United States
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature16986

Using satellite data and a novel analytical approach, a new index of the sensitivity of vegetation to climate variability is developed, revealing areas of high sensitivity that include tundra, boreal forest, tropical forest and temperate grasslands.
Climate-sensitive ecosystems identified
A key question in climate change research is how to identify the ecosystems most sensitive to climate variation. This study uses MODIS satellite data collected between February 2000 and December 2013 to develop a new metric, the 'vegetation sensitivity index', which measures ecosystem response to external forcing of three key climate variables — air temperature, water availability and cloud cover. The index can be used to identify the resilience status of ecosystems at high spatial resolution on a global scale. Areas of amplified sensitivity to climate variability are evident in Arctic tundra, boreal and tropical rainforest, alpine regions, steppe and prairie regions of central Asia and North and South America, the Caatinga deciduous forest in eastern South America, and eastern areas of Australia.
The identification of properties that contribute to the persistence and resilience of ecosystems despite climate change constitutes a research priority of global relevance
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. Here we present a novel, empirical approach to assess the relative sensitivity of ecosystems to climate variability, one property of resilience that builds on theoretical modelling work recognizing that systems closer to critical thresholds respond more sensitively to external perturbations
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. We develop a new metric, the vegetation sensitivity index, that identifies areas sensitive to climate variability over the past 14 years. The metric uses time series data derived from the moderate-resolution imaging spectroradiometer (MODIS) enhanced vegetation index
3
, and three climatic variables that drive vegetation productivity
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(air temperature, water availability and cloud cover). Underlying the analysis is an autoregressive modelling approach used to identify climate drivers of vegetation productivity on monthly timescales, in addition to regions with memory effects and reduced response rates to external forcing
5
. We find ecologically sensitive regions with amplified responses to climate variability in the Arctic tundra, parts of the boreal forest belt, the tropical rainforest, alpine regions worldwide, steppe and prairie regions of central Asia and North and South America, the Caatinga deciduous forest in eastern South America, and eastern areas of Australia. Our study provides a quantitative methodology for assessing the relative response rate of ecosystems—be they natural or with a strong anthropogenic signature—to environmental variability, which is the first step towards addressing why some regions appear to be more sensitive than others, and what impact this has on the resilience of ecosystem service provision and human well-being.