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Desert refugia under a changing climate : special and temporal patterns of botanical diversity in a hyper-arid mountain system


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Presented during the 17h Annual Sahelo-Saharan Interest Group Meeting organized by the NGO Sahara Conservation Fund in Senegal, from 4 to 6 May 2017. The Sahara Conservation Fund (SCF) gathers every year about a hundred people who are interested in the field of Sahelo-Saharan species conservation.

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Desert refugia under a changing climate : special and temporal patterns of botanical diversity in a hyper-arid mountain system

  1. 1. 17th Annual Sahelo-Saharan Interest Group Meeting 2 days of talks on biodiversity conservation in the Sahara and in the Sahel Desert refugia under a changing climate : spatial ad temporal patters of botanical diversity in a hyper-arid mountain system Peter COALS et al., Researcher – WildCRU, University of Oxford May 4 – 6, 2017
  2. 2. Desert refugia under a changing climate Spatial and temporal patterns of botanical diversity in a hyper-arid mountain system Peter Coals 1* Avi Shmida 2, Amiel Vasl 3, Nasr Mansour Duguny 4 & Francis Gilbert 1 1. School of Life Sciences, University of Nottingham, Nottingham NG7 2RD, UK 2. Dept. of Ecology, Evolution & Behavior, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel. 3. Leon Blaustein Ecology Lab, University of Haifa, Haifa 31905, Israel. 4. Abu Seila, St Katherine, South Sinai, Egypt.
  3. 3. Outline • Background • Global climate change • Biodiversity loss • Finger-prints of climate change; range contraction • Knowledge gaps and research needs • Research question • Study site • Data collection • Results • Conclusions • Conservation implications and future directions
  4. 4. Background • Global climate change: • Rapidly recent temperature increases • Predicted to continue Dufresne, J. L., Foujols, M. A., Denvil, S., Caubel, A., Marti, O., Aumont, O., ... & Bony, S. 2013. Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5. Climate Dynamics, 40(9-10), 2123-2165. Time evolution of the global mean surface air temperature anomaly (Dufresne et al. 2013)
  5. 5. Climate change & biodiversity loss Bellard, C., Bertelsmeier, C., Leadley, P., Thuiller, W. & Courchamp, F. 2012. Impacts of climate change on the future of biodiversity. Ecology Letters 15(4): 365-377. • Climate change is a significant driver of current and predicted biodiversity loss across taxa. Projections of biodiversity losses driven by climate change (Bellard et al. 2012)
  6. 6. Finger-prints of climate change • Shifting climatic zones reduce suitable habitat area, leading to isolation of populations and subsequent mountain-top extinctions • Range restricted species are especially vulnerable to range contraction, upslope movement, and mountain-top extinction. Parmesan, C. 2006. Ecological and evolutionary responses to recent climate change. Annual Review of Ecology, Evolution and Systematics 37: 637-669.
  7. 7. Knowledge gaps; range shifts • Plants; mostly studied in temperate regions, little from subtropical and arid regions. • Lower altitudinal range limits are under researched, and rarely considered together with upper limits. • We present the first such study from the Middle East. Research effort (publications, N) on climate-related range shifts since 1850s for terrestrial ecoregions (Lenoir & Svenning 2015). Lenoir, J. & Svenning, J.-C. 2015. Climate-related range shifts - a global multidimensional synthesis and new research directions. Ecography 38: 15-28.
  8. 8. Research questions • What are the altitudinal patterns of diversity in a desert mountain floral refuge? • Is there evidence of recent altitudinal range shifts in a hyper-arid Middle Eastern desert mountain flora? • How do directions of shift for upper and lower altitudinal range limits of plants vary?
  9. 9. Location • St Katherine Protectorate (SKP), South Sinai, Egypt 4350 km2 of the southern peninsula of Sinai Altitude to 2643m (Egypt’s tallest mountain)
  10. 10. SKP Flora • 19 of Egypt’s 33 endemic plant species. • One of the most important centres of plant diversity in the Middle East (IUCN, 1994). • Many species of plants exhibit disjunct distributions of Holarctic species found more commonly further north, suggesting that these species are relics of a more humid, colder past. IUCN. 1994. Centres for plant diversity: a guide and strategy for their conservation. IUCN, Cambridge, UK. Crataegus x sinaincus
  11. 11. Refugial pattern of diversity • Temperate flora remnant species remain only at higher altitudes. • Hill numbers diversity indices: • (a) 0D: Increasing species richness with altitude. • (b) 1D: Decreasing typical species with altitude. • (c) 2D: Increasing common species with altitude. • Communities become more uneven at higher altitudes with a few species showing increasing levels of dominance. • Thus increased species richness at high altitudes consists mainly of rare species.
  12. 12. Endemics • Endemics peak in density at high altitudes • (a) Plantago sinaica • (b) Polygala sinaica • (c) Silene schimperiana
  13. 13. Data collection • Field surveys: • October to mid-December 2014 • Surveys were carried out in mountainous areas predominantly within an igneous ring-dyke area over an altitude range of 1324 m to 2629 m. • Locations of transects was chosen to cover all major habitat types. • Quadrats of area 100 m2 every 50 m change in elevation. • 36 sites; 283 quadrats; 28300 m2. • Abundances of all species recorded.
  14. 14. • Comparison of field data with a 1970s dataset compiled by Arbel & Shmida (1979) within the St Katherine ring-dyke • Method replicated by 2014 surveys. • Lower resolution; quadrats placed every 200m change in altitude. • Raw data unavailable from 1970s only upper and lower altitudinal limits of species occurrences available. • Paired species 2014-1970s: • 81 species; upper altitudinal limits • 25 species; lower altitudinal limits • More than 10 individuals recorded during the 2014 field surveys: • 63 upper limits • 22 lower limits Arbel O. & Shmida A .1979. The vegetation of the high mountains of South Sinai. Society for the Protection of Nature. Tel Aviv. 67 pp. [in Hebrew].
  15. 15. Results • Is there evidence of recent altitudinal range shifts in a hyper-arid Middle Eastern desert mountain flora? • Predictions: • Upper altitudinal range limits shift upslope. • Lower altitudinal range limits shift upslope.
  16. 16. Results; upper limits • Predicted increase in mean upper altitudinal limit 1970s-2014: • Significant increase in mean upper altitudinal limits (mean 2014: 2228.6 ± 294.5 m, mean 1970 2125.2 ± 350.2 m: 1-tailed paired t = 3.37, df = 61, p<0.001).
  17. 17. Species limit shifts • Significantly greater numbers of species upper range limits moved upslope (resolution over 100 m): • Movement of over 100 m (26/40, binomial test p=0.04). • Movement of over 250 m (16/18, binomial test p<0.001).
  18. 18. Results; lower limits • Predicted increase in mean lower altitudinal limit 1970s to 2014: • Significantly reduced mean lower altitudinal limit (current mean 1568.0 ± 162.1 m, past mean 1668.2 ± 166.6 m; paired t = 3.02, df = 20, p=0.0064).
  19. 19. Species limit shifts • Significantly greater number of species decreased their individual lower altitudinal limits than did not (17/22, binomial test p=0.008) • Movement over 100 m (12/13, binomial test p=0.002).
  20. 20. Summary • Mean upper limits and majority of species showed upslope movement. • In line with predictions. • Mean lower limits and majority of species showed downslope movement. • Contrary to predictions. • Suggests that factors in addition to temperature are influencing lower limit shifts. • Scope of study limited by lack of historical data. • Check it isn’t annual variation…
  21. 21. Shrubs & Trees • Support full data for larger movements: • Higher mean upper limits (present mean 2219.1 ± 311.2 m, past mean 2139.5 ± 353.3 m: paired t = 2.30, df = 36, p=0.027). • Lower limits of shrubs and trees were also significantly lower in the present data (1585.7 ± 145.7 m) than in the 1970s (1725.0 ± 171.8 m: paired t = 5.27, df = 12, p=0.0002). Upper range limits Lower range limits All species No majority upslope (21/38, p=0.31) Majority downslope (14/16, p=0.006) Movement > 100 m No majority upslope (15/22, p=0.07) Majority downslope (9/9, p=0.006) Movement > 250 m Majority upslope (7/8, p=0.04) N.A.
  22. 22. Species’ paired limit movements Species Limit movement patterns Range size change Lower limit Upper limit Alkanna orientalis down stationary expanded Astragalus echinus down down no change Calipeltis cucullaris stationary up expanded Colchicum guessfeldtianum up down contracted Cotoneaster orbicularis stationary up expanded Crataegus x sinaica stationary stationary no change Globularia arabica down up expanded Nepeta septemcrenata stationary down contracted Origanum syriacum down stationary expanded Phlomis aurea down up expanded Polygala sinaica down stationary expanded Pterocephalus sanctus stationary stationary no change Pulicaria undulata stationary up expanded Rubus sanctus down stationary expanded Salvia multicaulis down down expanded Scariola orientalis down down expanded Silene leucophylla down up expanded Silene schimperiana stationary down contracted Stipa parviflora stationary up expanded Thymus decussatus down down expanded Verbascum decaisneanum stationary up expanded Verbascum sinaiticum down up expanded Endemics: Polygala sinaica gained ~200m lower range limit. Silene schimperiana lost ~100m altitudinal range at high range limit.
  23. 23. Conclusions • Simple predictions of upslope shifts are and contracting ranges are not met. • Wider climate change, including changes in water balance, area of bare soil surface and elevated atmospheric carbon dioxide levels may influence range shifts in plants. • Reliable climatic and environmental information is lacking in South Sinai. • Further research of drivers of range shifts in arid lands are required.
  24. 24. Conservation for desert mountain flora under changing climate • Many species show expansions of their altitudinal ranges. • Low present threat posed by range contraction. • However, the Sinai endemic Silene schimperiana has contracted in altitudinal range. • Risk must be considered on a case-by-case basis for Sinai’s endemic and rare species. • Further similar studies required across other desert regions. • Whilst we cannot conclusively state that observed point to environmental change that may pose ecological and conservation issues for the future. • Highlight the necessity of increasing the comprehensiveness and quality of the region’s environmental monitoring programmes. • Only through the collection and use of detailed fine-scale data can the underlying causes and conservation implications of observed range shifts be determined.
  25. 25. Our thanks to the Egyptian Environmental Affairs Agency for permission to carry out the 2014 work, and we are very grateful to Mr Mohamed Kotb and the rangers of the St Katherine Protected Area for their support for our work in this and other projects. We are hugely grateful to Ibrahim ElGamal whose botanical and terrain expertise significantly enhanced the quality of this work.