Mapping climatic mechanisms likely to favour the emergence of novel communities implications for the emergence of novel communities

Transcription

1 SUPPLEMENTARY INFORMATION DOI:.38/NCLIMATE327 Mapping climatic mechanisms likely to favour the emergence of novel communities implications for the emergence of novel communities Alejandro Ordonez *, John W Williams 2,3, Jens-Christian Svenning Section of Ecoinformatics and Biodiversity, Department of Bioscience, Aarhus University, Ny Munkegade 4, DK-8 Aarhus C, Denmark, 2 Center for Climatic Research (CCR), University of Wisconsin, Madison, Wisconsin 5376, USA 3 Department of Geography, University of Wisconsin, Madison, Wisconsin 5376, Supporting Information Overview USA. This document provides supplementary information not provided in the main text of the article Climatic novelty, displacement, and divergence: implications for the emergence of novel communities. The file includes the summary of geometric means of climatic speeds and bearing for mean annual temperature and annual precipitation (Table a,b); an overview of how we estimate displacement and divergence (Figure ); assessment of the effect of spatial resolution on bearing angle and displacement of temperature and precipitation velocity vectors for 9-23 (Figure 2); assessment of variations in velocity and bearing for selected multidecadal subsets (Figure 3); and climate novelty of selected multi-decadal periods relative to a 9-92 baseline (Figure 4). NATURE CLIMATE CHANGE 26 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

2 SUPPLEMENTARY INFORMATION DOI:.38/NCLIMATE327 Supplementary Table a. Summary of geometric means of climatic velocities for mean annual temperature and annual precipitation. Velocity vectors estimated using 2.5-arcmin resolution data and ref. vector-based specification of ref. 2 climate velocity. Summaries represent geometric means of velocity estimates by WWF ecoregions 3 and globally. Annual precipitation velocity (km decade - ) Mean annual temperature velocity (km decade - ) Biomes Boreal Forests/Taiga Deserts & Xeric Shrublands Flooded Grasslands & Savannas Mangroves Mediterranean Forests, Woodlands & Scrub Montane Grasslands & Shrublands Temperate Broadleaf & Mixed Forests Temperate Conifer Forests Temperate Grasslands, Savannas & Shrublands Coniferous Forests Dry Broadleaf Forests Grasslands, Savannas & Shrublands Moist Broadleaf Forests Tundra Global mean NATURE CLIMATE CHANGE 26 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

3 DOI:.38/NCLIMATE327 SUPPLEMENTARY INFORMATION Biomes Supplementary table b. Summary of the mean bearing for mean annual temperature and precipitation. Velocity vectors estimated using 2.5-arcmin resolution data methods described in text. Summaries represent geometric means of velocity for WWF ecoregions and globally. 9 indicate a northward direction, 27 a southward direction, 8 a westward direction, and both and 8 indicate a eastward movement. Mean annual temperature bearing (degrees) Annual precipitation bearing (degrees) Boreal Forests/Taiga Deserts & Xeric Shrublands Flooded Grasslands & Savannas Mangroves Mediterranean Forests, Woodlands & Scrub Montane Grasslands & Shrublands Temperate Broadleaf & Mixed Forests Temperate Conifer Forests Temperate Grasslands, Savannas & Shrublands Coniferous Forests Dry Broadleaf Forests Grasslands, Savannas & Shrublands Moist Broadleaf Forests Tundra Global mean NATURE CLIMATE CHANGE Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

4 SUPPLEMENTARY INFORMATION DOI:.38/NCLIMATE327 Spatial gradients South to North gradient (temperature) High Low High (precipitation) Temperature Precipitation Spatial angle a b c Opposite gradients warm-dry to cold-wet Concordant gradients warm-wet to cold-dry Temporal changes Local trends in temperature (warming) & precipitation (four zones, varying direction) d e f Temporal angle Concordant changes Opposite changes Concordant changes Opposite changes g h Velocity vectors Speed and & Bearing i Displacement Low j Divergence High High Low Medium High Supplementary Figure Diagram showing how displacement and divergence are affected by underlying spatial gradients in climate variables and the local temporal change for each grid cell. To illustrate possible combinations of temperature and precipitation gradients, the temperature gradient (a) is shown as a south-to-north trend of decreasing temperatures (red representing warm and blue representing cold), while the precipitation gradient (b) has a mid-zonal low (red representing dry) and increases both to the north and south (blue representing wet). This example establishes two regions (c): a northern region where the temperature and precipitation gradients are opposite (temperature decreasing northwards while precipitation increases) and a southern region where the temperature and precipitation gradients are concordant (both decreasing northwards from warm/wet to cold/dry). In panel c), arrows indicate the direction of the local temperature (black) and precipitation (grey) gradients for each grid cell, based on analysis of the grid cell and its neighbours within a 3 3 grid cell window. The colour shading for each cell indicates the spatial angle, defined as the angle between the local temperature and precipitation gradients. Panel (d) shows the temporal changes in temperature, which in this example are set to be rising everywhere (red to white colours, that represent positive changes), with the largest rises in the southern region. The temporal 4 NATURE CLIMATE CHANGE 26 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

5 DOI:.38/NCLIMATE327 SUPPLEMENTARY INFORMATION precipitation changes (e), however, are more complex, with the northern and southern regions each having a band of increasing (white to blue colours representing a wetting of the region) precipitation and one of decreasing precipitation (red to white colours representing a drying of the region). The temporal angle (f) shows whether these temperature and precipitation changes are temporally trending in the same direction, i.e. both towards higher values or both towards lower values ( ), or in opposite directions (8 ). The speed and bearing for individual climate variables, calculated using a vector-based specification of climate velocity, 2 (Methods), is shown in panels (g) and (h). Speed is the rate at which a species would need to move to keep pace with the change in a environmental factor, and is affected both by the magnitude of the temporal changes at each grid cell and the steepness of the local spatial gradients. Arrows in panels (g) and (h) indicate the direction of movement required to track shifting climate, and reflect the orientation of the spatial gradient and the direction of temporal change (black for increase and purple for decrease) for the evaluated climatic variable. Here, when precipitation decreases over time, the direction of the climate vector reverses (purple arrows), indicating that species would have to move up-gradient to stay within their current climatic zone. Conversely, when precipitation increases, species move downgradient (black arrows) to stay in their current climatic zone. The mean rate of displacement (average speed of temperature and precipitation vectors) across temperature and precipitation is shown in panel (i) and ranges from higher rates in the middle to lower rates in the north and south. Divergence is shown in panel (h) and is calculated as the difference between the spatial angle (c) and temporal angle (f). An equivalent solution is to calculate divergence as the angles between the temperature and precipitation vectors shown in panels (g) and (h). Divergence determines the direction of movement required to track shifting climatic conditions based on the spatial gradient of the environmental variable and the direction of the temporal changes. Values close to zero indicate low divergence, meaning that temperature and precipitation changes should pull climate-sensitive species in the same direction, either because temporal and precipitation changes are temporally concordant (e.g. warming & wetting) in a region with concordant spatial gradients, or because temporal and precipitation changes are locally opposite (e.g. warming and drying) in a region with locally opposite climatic gradients. Values close to 8 indicate high divergence, meaning that climate changes should pull climate-sensitive species in opposite directions, depending on their relative sensitivity to temperature and moisture changes. High divergence can occur either when temporal changes in temperature and precipitation are concordant in a region where local temperature and precipitation gradients are opposite or when temporal changes in temperature and precipitation are opposite in a region where local temperature and precipitation gradients are concordant. NATURE CLIMATE CHANGE Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

6 SUPPLEMENTARY INFORMATION DOI:.38/NCLIMATE Arc-Minutes 5 Arc-Minutes a Bearing [degrees] 27 c Bearing [degrees] Mean annual temperature 3.4 log (Velocity) [km*decade ] b Bearing [degrees] d Bearing [degrees] Total annual precipitation 2.22 log (Velocity) [km*decade ] Arc-Minutes 3 Arc-Minutes e Bearing [degrees] 27 g Bearing [degrees] log (Velocity) [km*decade ] 5.94 log (Velocity) [km*decade ] 8.64 log (Velocity) [km*decade ] Supplementary Figure 2. Bi-variate frequency distribution of bearing angles (degrees) and displacement (km decade - ) of temperature and precipitation velocity vectors from 9 to 23 for different spatial resolutions. Kerneldensity plots indicate the frequency () of bearing angles (9-degrees indicate a northward direction and 27-degrees indicate a southward direction of velocity vectors) and displacement (speed of velocity vectors) across the globe. Estimates are based on four different climate data resolution: 3 arc-minutes (a-b); arc-minutes (c-d); 5 arc-minutes (e-f) and 2.5 arc-minutes (gh). Dashed line and value on the top of each panel shows the geometric mean for global displacement f Bearing [degrees] h Bearing [degrees] log (Velocity) [km*decade ] 3. log (Velocity) [km*decade ] 4.9 log (Velocity) [km*decade ] NATURE CLIMATE CHANGE 26 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

7 DOI:.38/NCLIMATE327 SUPPLEMENTARY INFORMATION 2.5 Arc-Minutes 5 Arc-Minutes Arc-Minutes 3 Arc-Minutes a 9 to 945 b 945 to 975 c 975 to *** log (Displacement) [km*decade d ] log (Displacement) [km*decade e ] f log g (Displacement) [km*decade ] log h (Displacement) [km*decade ] i log j (Displacement) [km*decade ] log k (Displacement) [km*decade ] l ***.9 ***.8 *** log (Displacement) [km*decade ] ***.3 ***.3 ***.3 *** Supplementary Figure 3. Bi-variate frequency distribution of divergence (degrees) and average displacement (km decade - ) for temperature and precipitation velocity vectors for three time intervals (9 945; ; ). Kernel-density plots indicate the combined frequency (number of cells per bivariate bin) of divergence and displacement values across the globe. Estimates are based on four spatial resolutions of climate data: 2.5 arc-minutes (a-c); 5 arcminutes (d-f); arc-minutes (g-i) and 3 arc-minutes (j-l). Dashed line and value on the top of each panel shows the geometric mean for global total climatic displacement. Values at the bottom-left corner of each panel show the Dutilleul s corrected Pearson s correlation coefficients significance (*** p<., ** p<., * p<.5, and N.S. p.5) between divergence and displacement log (Displacement) [km*decade ] ***.47 log (Displacement) [km*decade ].9 *** 4.69 log (Displacement) [km*decade ].2 *** 8.2 log (Displacement) [km*decade ].2 N.S log (Displacement) [km*decade ] NATURE CLIMATE CHANGE Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

8 Supporting Information Ordonez et al. Climatic novelty, displacement and divergence DOI:.38/NCLIMATE327 SUPPLEMENTARY INFORMATION Climate Novelty SEDmin Climate Novelty SEDmin Climate Novelty SEDmin Climate Novelty SEDmin Supplementary Figure 4. Climatic novelty for selected 2-year periods during the last years. Climate novelty of 2-year average climates was measured using minimum standardized Euclidean distance (SEDmin; methods) to 9-92 climates. The threshold value defining no-analog climate (SEDt; Methods) is marked as triangle in the color bar; so that that blue-to-cyan shows SEDmin<SEDt (Methods) and yellow-tored SEDmin>SEDt. NATURE CLIMATE CHANGE 26 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. 8

9 DOI:.38/NCLIMATE327 SUPPLEMENTARY INFORMATION References. Burrows MT, Schoeman DS, Buckley LB, Moore P, Poloczanska ES, Brander KM, et al. The pace of shifting climate in marine and terrestrial ecosystems. Science 2, 334(656): Loarie SR, Duffy PB, Hamilton H, Asner GP, Field CB, Ackerly DD. The velocity of climate change. Nature 29, 462(7276): Olson DM, Dinerstein E, Wikramanayake ED, Burgess ND, Powell GVN, Underwood EC, et al. Terrestrial ecoregions of the worlds: A new map of life on Earth. Bioscience 2, 5(): NATURE CLIMATE CHANGE Macmillan Publishers Limited, part of Springer Nature. All rights reserved.