Revealing turning points in ecosystem functioning over the Northern Eurasian agricultural frontier

The collapse of the Soviet Union in 1991 has been a turning point in the World history that left a unique footprint on the Northern Eurasian ecosystems. Conducting large scale mapping of environmental change and separating between naturogenic and anthropogenic drivers is a difficult endeavor in such highly complex systems. In this research a piece-wise linear regression method was used for breakpoint detection in Rain-Use Efficiency (RUE) time series and a classification of ecosystem response types was produced. Supported by earth observation data, field data, and expert knowledge, this study provides empirical evidence regarding the occurrence of drastic changes in RUE (assessment of the timing, the direction and the significance of these changes) in Northern Eurasian ecosystems between 1982 and 2011. About 36% of the study area (3.4 million km(2) ) showed significant (P < 0.05) trends and/or turning points in RUE during the observation period. A large proportion of detected turning points in RUE occurred around the fall of the Soviet Union in 1991 and in the following years which were attributed to widespread agricultural land abandonment. Our study also showed that recurrent droughts deeply affected vegetation productivity throughout the observation period, with a general worsening of the drought conditions in recent years. Moreover, recent human-induced turning points in ecosystem functioning were detected and attributed to ongoing recultivation and change in irrigation practices in the Volgograd region, and to increased salinization and increased grazing intensity around Lake Balkhash. The ecosystem-state assessment method introduced here proved to be a valuable support that highlighted hotspots of potentially altered ecosystems and allowed for disentangling human from climatic disturbances.

[1]  J. Ardö,et al.  Detecting changes in vegetation trends using time series segmentation , 2015 .

[2]  C. Tucker,et al.  Variations in northern vegetation activity inferred from satellite data of vegetation index during 1981 to 1999 , 2001 .

[3]  Achim Zeileis,et al.  Shifts in Global Vegetation Activity Trends , 2013, Remote. Sens..

[4]  Kurt Jax,et al.  Function and “functioning” in ecology: what does it mean? , 2005 .

[5]  Geoffrey M. Henebry,et al.  Dual scale trend analysis for evaluating climatic and anthropogenic effects on the vegetated land surface in Russia and Kazakhstan , 2009 .

[6]  G. Ioffe,et al.  Land Abandonment in Russia , 2012 .

[7]  E. Wood,et al.  Global Trends and Variability in Soil Moisture and Drought Characteristics, 1950–2000, from Observation-Driven Simulations of the Terrestrial Hydrologic Cycle , 2008 .

[8]  Yu Zhou,et al.  Climate Contributions to Vegetation Variations in Central Asian Drylands: Pre- and Post-USSR Collapse , 2015, Remote. Sens..

[9]  Patrick Hostert,et al.  Rapid land use change after socio-economic disturbances: the collapse of the Soviet Union versus Chernobyl , 2011 .

[10]  J. Janowiak,et al.  The Global Precipitation Climatology Project (GPCP) combined precipitation dataset , 1997 .

[11]  Tao Zhang,et al.  Was there a basis for anticipating the 2010 Russian heat wave? , 2011 .

[12]  B. Sohn,et al.  Recent trends in changes of vegetation over East Asia coupled with temperature and rainfall variations , 2010 .

[13]  Per Jönsson,et al.  TIMESAT - a program for analyzing time-series of satellite sensor data , 2004, Comput. Geosci..

[14]  C. Tucker,et al.  Climate-Driven Increases in Global Terrestrial Net Primary Production from 1982 to 1999 , 2003, Science.

[15]  J. Zak,et al.  Convergence across biomes to a common rain-use efficiency , 2004, Nature.

[16]  G. Henebry,et al.  Using multiple remote sensing perspectives to identify and attribute land surface dynamics in Central Asia 2001–2013 , 2015 .

[17]  G. Luo,et al.  Salinization dynamics in irrigated soils of the Svetloyarsk irrigation system, Volgograd oblast , 2009 .

[18]  R. Fensholt,et al.  Evaluating temporal consistency of long-term global NDVI datasets for trend analysis , 2015 .

[19]  V. Radeloff,et al.  Effects of institutional changes on land use: agricultural land abandonment during the transition from state-command to market-driven economies in post-Soviet Eastern Europe , 2012 .

[20]  C. Tucker,et al.  Desertification in the Sahel: a reinterpretation of a reinterpretation , 2007 .

[21]  T. McMahon,et al.  Updated world map of the Köppen-Geiger climate classification , 2007 .

[22]  M. Hansen,et al.  Eastern Europe's forest cover dynamics from 1985 to 2012 quantified from the full Landsat archive , 2015 .

[23]  Michael E. Schaepman,et al.  Desertification in the Sahel: Towards better accounting for ecosystem dynamics in the interpretation of remote sensing images , 2011 .

[24]  J. Janowiak,et al.  The Version 2 Global Precipitation Climatology Project (GPCP) Monthly Precipitation Analysis (1979-Present) , 2003 .

[25]  G. Henebry,et al.  Land surface phenology, climatic variation, and institutional change: Analyzing agricultural land cover change in Kazakhstan , 2004 .

[26]  Rob J Hyndman,et al.  Detecting trend and seasonal changes in satellite image time series , 2010 .

[27]  P. Jones,et al.  Global warming and changes in drought , 2014 .

[28]  Le Houérou,et al.  Rain use efficiency: a unifying concept in arid-land ecology , 1984 .

[29]  Mark West,et al.  C4 grasses prosper as carbon dioxide eliminates desiccation in warmed semi-arid grassland , 2011, Nature.

[30]  K. D. de Beurs,et al.  Use of Landsat and MODIS data to remotely estimate Russia’s sown area , 2014 .

[31]  G. Henebry,et al.  Climate and environmental change in arid Central Asia: impacts, vulnerability, and adaptations. , 2009 .

[32]  E. Coppola,et al.  Uncertainties in daily rainfall over Africa: assessment of gridded observation products and evaluation of a regional climate model simulation , 2013 .

[33]  P. Hostert,et al.  Mapping farmland abandonment and recultivation across Europe using MODIS NDVI time series. , 2015 .

[34]  K. de Beurs,et al.  Land Abandonment in Russia: A Case Study of Two Regions , 2012 .

[35]  Ben Somers,et al.  How to measure ecosystem stability? An evaluation of the reliability of stability metrics based on remote sensing time series across the major global ecosystems , 2014, Global change biology.

[36]  V. Penteriani.  When similar ecological patterns in time emerge from different initial conditions: equifinality in the breeding performance of animal populations , 2008 .

[37]  V. Radeloff,et al.  Using the Landsat record to detect forest-cover changes during and after the collapse of the Soviet Union in the temperate zone of European Russia , 2012 .

[38]  M. Schaepman,et al.  Proxy global assessment of land degradation , 2008 .

[39]  P. Heilman,et al.  An ecological assessment of pasturelands in the Balkhash area of Kazakhstan with remote sensing and models , 2012 .

[40]  Hui Fang,et al.  Changes in the area of inland lakes in arid regions of central Asia during the past 30 years , 2011, Environmental monitoring and assessment.

[41]  J. Bell,et al.  Rain use efficiency as affected by climate warming and biofuel harvest: results from a 12‐year field experiment , 2014 .

[42]  Alexey Terekhov,et al.  Long-term agricultural land-cover change and potential for cropland expansion in the former Virgin Lands area of Kazakhstan , 2015 .

[43]  M. S. Moran,et al.  Ecosystem resilience despite large-scale altered hydroclimatic conditions , 2013, Nature.

[44]  Alfons Balmann,et al.  Post‐Soviet cropland abandonment and carbon sequestration in European Russia, Ukraine, and Belarus , 2013 .

[45]  A. Belward,et al.  GLC2000: a new approach to global land cover mapping from Earth observation data , 2005 .

[46]  Alessandro Anav,et al.  Global Data Sets of Vegetation Leaf Area Index (LAI)3g and Fraction of Photosynthetically Active Radiation (FPAR)3g Derived from Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI3g) for the Period 1981 to 2011 , 2013, Remote. Sens..

[47]  Wolfgang Lucht,et al.  Tipping elements in the Earth's climate system , 2008, Proceedings of the National Academy of Sciences.

[48]  Rasmus Fensholt,et al.  Assessing Land Degradation/Recovery in the African Sahel from Long-Term Earth Observation Based Primary Productivity and Precipitation Relationships , 2013, Remote. Sens..

[49]  Edwin W. Pak,et al.  An extended AVHRR 8‐km NDVI dataset compatible with MODIS and SPOT vegetation NDVI data , 2005 .

[50]  Volker C. Radeloff,et al.  Determinants of agricultural land abandonment in post-Soviet European Russia , 2011 .

[51]  P. Ciais,et al.  Changes in satellite‐derived vegetation growth trend in temperate and boreal Eurasia from 1982 to 2006 , 2011 .

[52]  J. Evans,et al.  Discrimination between climate and human-induced dryland degradation. , 2004 .

[53]  Tim R. McVicar,et al.  Global evaluation of four AVHRR-NDVI data sets: Intercomparison and assessment against Landsat imagery , 2011 .

[54]  Anja Linstädter,et al.  Meta‐analysis of ANPP and rain‐use efficiency confirms indicative value for degradation and supports non‐linear response along precipitation gradients in drylands , 2012 .

[55]  U. Gessner,et al.  Regional land cover mapping and change detection in Central Asia using MODIS time-series , 2012 .

[56]  T. Lenton.  Early warning of climate tipping points , 2011 .

[57]  S. Bruin,et al.  Trend changes in global greening and browning: contribution of short‐term trends to longer‐term change , 2012 .

[58]  Jonathan M. Adams,et al.  Impacts of Climate and Land-cover Changes in Arid Lands of Central Asia , 2005 .

[59]  G. Henebry,et al.  Combined analysis of land cover change and NDVI trends in the Northern Eurasian grain belt , 2012, Frontiers of Earth Science.

[60]  M. Spoor.  Transition to Market Economies in Former Soviet Central Asia: Dependency, Cotton and Water , 1993 .

[61]  T. McVicar,et al.  Impact of CO2 fertilization on maximum foliage cover across the globe's warm, arid environments , 2013 .

[62]  Yi Y. Liu,et al.  Contribution of semi-arid ecosystems to interannual variability of the global carbon cycle , 2014, Nature.

[63]  Aaron Moody,et al.  Geographical distribution of global greening trends and their climatic correlates: 1982–1998 , 2005 .

[64]  S. Seneviratne,et al.  Global assessment of trends in wetting and drying over land , 2014 .

[65]  Rasmus Fensholt,et al.  Global-scale mapping of changes in ecosystem functioning from earth observation-based trends in total and recurrent vegetation , 2015 .

[66]  Guiling Wang.  Agricultural drought in a future climate: results from 15 global climate models participating in the IPCC 4th assessment , 2005 .

[67]  Reinhard Furrer,et al.  Spatial relationship between climatologies and changes in global vegetation activity , 2013, Global change biology.

[68]  V. Radeloff,et al.  Regional- and district-level drivers of timber harvesting in European Russia after the collapse of the Soviet Union , 2011 .

[69]  Anja Linstädter,et al.  Quantifying drylands' drought resistance and recovery: the importance of drought intensity, dominant life history and grazing regime , 2015, Global change biology.

[70]  Rasmus Fensholt,et al.  Greenness in semi-arid areas across the globe 1981–2007 — an Earth Observing Satellite based analysis of trends and drivers , 2012 .

[71]  Keith R. Briffa,et al.  A scPDSI‐based global data set of dry and wet spells for 1901–2009 , 2013 .