1. Climate change in unpredictable terrestrial ecosystems: an integrative approach along an aridity gradient in Israel Marcelo Sternberg Department of Molecular Biology & Ecology of Plants Tel Aviv University, Israel

2. GLOWA – Jordan River GLOWA Global water cycle Water cycle: dominant cause of uncertainty in climate change projections Soil moisture Water vapor (dew & air humidity Evapo-transpiration & evaporation Climate changeLand use change + & - feedbacks

3. Green water: terrestrial ecosystems Precipitation–the basic water resource GW Falkenmark 2003

4. GLOWA – Jordan River Or…. Being a prophet in the “Land of Prophets”…… ……… a tough job What will happen to natural ecosystems and their “users”?

5. Alon Angert, Jose Gruenzweig, Jaime Kigel, Irit Konsens The Hebrew University of Jerusalem, Israel Research partners Katja Tielboerger Tuebingen University, Germany Yossi Steinberger Bar-Ilan University, Israel

6. Global Climate Change in the Middle East Current global climate change models predict changes in temperature and rainfall in the Mediterranean basin region.  Higher summer & autumn temperatures  Lower winter rainfall Black, 2009; Klafe & Bruins, 2009

7. The gradient: Mesic Mediterranean AridSemiaridMediterranean Study sites

8. Rainfall along the aridity gradient Rainfall (mm) Source: IMS

9. Rainfall CV (%) Rainfall predictability along the aridity gradient Source: IMS

10. Topography South-facing slopes with stony and shallow soil (Terra rossa to desert lithosol on hard limestone and chalk) Temperature Mean annual temperature 18 0 C-19 0 C Rainfall Mainly winter - 5 summer months with no rainfall Range North-South: 780 to 90 mm ~ 245 km Mesic Mediterranean - 780 mm – CV 22% Mediterranean - 540 mm – CV 30% Semiarid – 300 mm – CV 37% Arid – 90 mm – CV 51% Aridity gradient

11. Rainfall (mm) 0 100 200 300 400 500 600 700 800 Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Oct-07 Mesic Mediterranean Mediterranean Semiarid Arid 795 mm 609 mm 270 mm Rainfall along the gradient Date Differences in length of the growing season Talmor et al., 2010 GCB 100 mm

12. Experimentally testing the effects of climate change Sprinkler Irrigated Plots (25 x 10 m) – 30% increase Rainout Shelters (25 x 10 m) – 30% reduction

13. DroughtSupplemented rainfall Mediterranean 540 mm Semiarid 300 mm Arid 90 mm Mesic Mediterranean 780 mm N Experimental design

14. DroughtSupplemented rainfall MAT Mediterranean 540 mm LAH Semiarid 300 mm SDE Arid 90 mm EIN - Mesic Mediterranean 780 mm N Experimental design

15. Data collection – Gradient vs. manipulation data Rainfall manipulationsGradient Vegetation NPP Species richness Species diversity Soil seed banks Seedling mortality Ecosystem Soil respiration NO 3, NH 4 & PO 4 P (d 18 O p ) Plant litter decomposition Soil mesofauna Ground insects (beetles) Vegetation NPP Species richness Species diversity Soil seed banks Seedling mortality Ecosystem Soil respiration NO 3, NH 4 & PO 4 P (d 18 O p ) Soil microbial biomass Soil Fungi Plant root and litter decomposition Soil mesofauna Ground insect (beetles)

16. The gradient: Mesic Mediterranean AridSemiaridMediterranean Results

17. NO 3 - increased with increasing rainfall – P decreased at the most mesic site – seasonal changes Soil nutrients along the gradient MediterraneanAridMesic Med.Semiarid Time

18. N and OC increases with increasing rainfall – seasonal changes Soil nutrients along the gradient MediterraneanAridMesic Med.Semiarid Time % N

19. Linear relationship between annual rainfall and herbaceous biomass production until 450 mm Primary productivity along the gradient Kigel et al., unpublished MediterraneanAridMesic Med.Semiarid

20. No linear relationship between rainfall & spp. richness at the mesic sites Species richness along the gradient Kigel et al., unpublished 200320052002200620072008200920042010 MediterraneanAridMesic Med.Semiarid Year

21. Species richness and rainfall along the gradient Kigel et al., unpublished MediterraneanAridMesic Med.Semiarid

22. Species richness & APP correlation along the gradient Kigel et al., unpublished MediterraneanAridMesic Med.Semiarid

23. Soil seed bank

24. Changes in seed bank density along the aridity gradient Mediter. arid mesic Mediter. semiarid Important differences among sites & years Strong densities variation with rainfall at the mesic sites Mean No of seedlings (m -2 ) Station *** Year *** S x Y *** Year

25. Changes in community structure along the aridity gradient Species richness Species evenness (J’) Year Mediter. arid mesic Mediter. semiarid Important differences among sites. No linear relation between rainfall and spp. richness & diversity. Decreasing trend of spp. richness at the more mesic sites Station *** Year *** S x Y *** Station *** Year *** S x Y ** Species diversity (H’)

26. Experimentally testing the effects of climate change Sprinkler Irrigated Plots (25 x 10 m) – 30% increase Rainout Shelters (25 x 10 m) – 30% reduction

27. Climate treatment effects on primary productivity Rainfall manipulations had a significant effect on biomass production at the semiarid station only Year Kigel et al., unpublished Year *** Treatment NS T x Y NS Year *** Treatment ** T x Y NS

28. Climate treatment effects on primary productivity Effective rainfall manipulations had a significant effect on biomass production at the semiarid station only Kigel et al., unpublished

29. Effects of rainfall manipulations on seed bank density watering drought rainfall control Rainfall (mm) Year Treat. NS Year *** T x Y NS Semiarid Mediterranean Mean No of seedlings (m -2 ) Treat. NS Year *** T x Y NS

30. watering drought rainfall control Rainfall (mm) Year Treat. NS Year *** T x Y NS Semiarid Mediterranean Mean No of seedlings (m -2 ) Treat. NS Year *** T x Y NS No treatment effect on seed bank density

31. Effects of rainfall manipulations on community structure – Mediterranean site watering drought rainfall control Species richness Species diversity (H’) Treat. NS Year *** T x Y NS Rainfall (mm) Year

32. watering drought rainfall control Species richness Species diversity (H’) Treat. NS Year *** T x Y NS Rainfall (mm) Year No rainfall manipulations effects on community structure – Mediterranean site Similar results at the semiarid site

34. Effects of rainfall manipulations on insect density Shtirberg et al., unpublished

35. Effects of rainfall manipulations on insect density Shtirberg et al., unpublished 0 200 400 600 800 1000 1200 1400 DroughtControlWatering Treatment Mediterranean Semiarid Mean No of insects 0 200 400 600 800 1000 1200 1400 DroughtControlWatering Treatment ‘07‘06‘07‘06‘07‘06 ‘07‘06‘07‘06‘07‘06 Treat. NS Year *** T x Y NS

36. Jan-06Apr-06Jul-06Oct-06Jan-07Apr-07Jul-07Oct-07 Volumetric SWC (%) Rainfall (mm) R s ( µ mol CO 2 m -2 s -1 ) Rainfall, soil moisture & soil respiration Talmor et al., 2011 GCB

37. 0 200 400 600 800 1000 OpenShrubOpenShrub MediterraneanSemiarid Wet Control Dry p<0.05 A AB B R s ( g C m -2 y -1 ) Soil respiration & rainfall manipulations Talmor et al., 2010

38. Effects of rainfall manipulations on soil microbial biomass MediterraneanSemiarid Microbial biomass (µg C g soil -1 ) 2008 & ‘09 Seasons & Treatments Sherman et al., unpublished Season – significant changes No consistent pattern of treatment response 2008 2009 WinterSpringSummerAutumn

39. 1)Soil nutrients, primary productivity, soil seed bank (SSB) density, species richness, species diversity varies strongly along the aridity gradient 2)No linear relationship between rainfall, NPP and species richness – P limitation at more mesic ecosystems? 3)Seed density correlates rainfall amounts (resource availability) along the aridity gradient, however differences among years are not necessarily reflected in higher number of seeds Conclusions

40. 4) The rainfall manipulations have not led to the hypothesized changes in soil properties, species density and community structure of the soil seed bank & insects. Plant communities proved to be resistant to this short- term climatic changes, particularly to drought. Increase of NPP at the semiarid indicates release of limiting factor. 5)We assume, that community resistance is mainly due to the vegetation “adaptation” to high temporal variability in rainfall, combined with high spatial heterogeneity. These characteristics buffers short-term changes. Conclusions

41. 7)Ecosystem level response (SR) to the rainfall manipulations indicates a different scale of response. Soil biota may respond faster to changes (i.e. higher generation turnover) 8)The detected short-term resistance does not necessarily imply resistance to long-term global climate change. More years are needed….. Conclusions

42. Conclusions Eastern Mediterranean ecosystems have evolved under high climatic variability conditions, high levels of stress and perturbations – Ecosystems characterized by high spatial & temporal variability Does this make them less vulnerable to climate change? In press GCB

43. Take home message Vulnerability to climate change decreases with increasing long-term climatic variability

44. Thanks!! Questions? MarceloS@tauex.tau.ac.il

45. species diversity – changes is composition similarity between stations and years species diversity – changes is composition similarity between stations and years Arid ‘02Semiarid ‘02Medit. ’02M. Med ‘02Arid ‘07Semiarid ‘07Med. ‘07M. Med ‘07 Arid ‘02 - Semiarid ‘02 0.57- Medit. ‘02 0.390.64- Mesic Med ‘02 0.430.550.64- Arid 2007 0.390.650.570.39- Semiarid ’07 0.390.740.620.570.70- Medit. ’07 0.320.550.670.560.520.67- M. Med ‘07 0.210.440.620.690.430.450.63- βsim (Simpson's based; reduces biases from imbalances in species richness between samples) Similarity in species composition between and among stations decreased with time at the arid sites

46. Soil fungi species richness along the gradient Steinberger et al., unpublished MediterraneanAridMesic Med.Semiarid

47. RII index (S-O/S+O) -0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 Mesic. Medit.Medit.SemiaridArid a ab bc c Shrub understory vs. open areas along the gradient Relative Interaction Intensity – Seedling density *** Sites along the gradient

48. Germination (%) Changes in germination strategies along the aridity gradient 2 nd germination year 3 rd germination year 1 st germination year 0 b bb a a abb b b b a 100 mesicMedit SemiaridArid b bb a a abb b b b a 80 b bb a a abb b b b a *** Site b bb a a abb b b b a 60 Higher germination fractions at the arid extreme of the gradient

49. Germination (%) Treatment 40% 60 80 100 DroughtControlIrrigation n.s 60 80 100 DroughtControlIrrigation n.s 0 0 Climate treatment effects on germination strategies Semiarid Mediterranean 2 nd germination year 3 rd germination year 1 st germination year

50. Germination (%) Treatment 40% 60 80 100 DroughtControlIrrigation n.s 60 80 100 DroughtControlIrrigation n.s 0 0 No treatment effect Semiarid Mediterranean 2 nd germination year 3 rd germination year 1 st germination year

51. Plant density & species richness Mediterranean station: Density: Strong temporal fluctuation. Wet (and dry) lower than control No treatment effect Richness: Weak temporal fluctuation, No change by treatment. Semiarid site similar pattern! Metz et al., 2010

52. Soil respiration & rainfall manipulations

53. Shrub understory vs. open areas along the gradient - Species richness shrub rainfall open Species richness mesic MediterraneanArid Habitat differential effect on species richness between arid vs. mesic Med. No direct relationship between rainfall and spp. richness Habitat * Year *** H x Y NS Habitat *** Year *** H x Y NS Year Rainfall (mm)