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GLOBAL ALPINES

GLOBAL ALPINES. ALPINE GARDEN SOCIETY East Anglian Conference 23 April 2005. ALPINE PLANTS OF THE AMERICAS. John and Hilary Birks. The Americas. The Americas A confession! State of floristic knowledge Environmental features Vegetation zonation Tree-line in the Americas

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GLOBAL ALPINES

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  1. GLOBAL ALPINES ALPINE GARDEN SOCIETY East Anglian Conference 23 April 2005

  2. ALPINE PLANTS OF THE AMERICAS John and Hilary Birks

  3. The Americas The Americas A confession! State of floristic knowledge Environmental features Vegetation zonation Tree-line in the Americas Extent of the alpine-zone in the Americas Richness of alpines General comparisons of alpines in the Americas Alpine species richness patterns Species in common Genera in common Families in common Primarily North American families Primarily South American families Possible floristic history Threats to survival and conservation Final comments

  4. A Confession! 'The Americas' is a very misleading title Western North America - 10 visits Patagonia - 2 visits More correct title: 'Alpine Plants of Western North America and Patagonia' Alpine plants difficult to define here because in some areas it is too dry for trees to grow. Steppe zone merges into alpine zone. No clear distinction between an 'alpine' and a 'steppe' plant.

  5. State of Floristic Knowledge North America – mainly state floras of variable quality

  6. Flora of North America - Started in 19938 volumes of a projected 30 volumes ca. 17 000 species, 1 200 genera, 220 families

  7. Flora Patagonica 1969-1999 8 volumes ca. 2 400 species, 738 genera, 138 families

  8. We will use the only source of consistent nomenclature for North and South American alpines, namely Alpine Garden Society Encyclopaedia of Alpines edited by Kenneth Beckett

  9. Environmental Features • Low temperatures, long-lasting or permanent snow, glaciers • Steep rocky slopes. Screes, cliffs, exposed ridges, and summits • Temperature decreases, on average, 0.65ºC per 100 m altitude • High winds 'Roaring Forties' and 'Furious Fifties' in South America • "In few parts of the world is the climate of a region and its life so determined by a single meteorological element, as is the climate of Patagonia by the constancy and strength of the wind." • Coronato (1993) • Wind chill reduces mean annual temperature perception by 4.2ºC • Strong west to east gradients in annual rainfall over small distances (200-300 km) • 7 m to 200 mm from western Chile to Puerto Santa Cruz • 3 m to 200 mm from coastal Oregon to Steens Mountain

  10. Vegetation Zonation - (Hypothetical!) 1. Central Patagonia – 41ºS – latitude of Bariloche 2500 2000 1500 1000 500 0 permanent snow and ice NIVAL snowbeds SUB-NIVAL alpine grassland alpine semi-desert ALPINE SUB-ALPINE evergreen Nothofagus pumilo krummholz Araucaria woodland Altitude (m)  Temperature deciduous Nothofagus forest species-poor steppe species-poor temperate rainforest temperate forest open xeric woodland steppe temperate rainforest 3500 2500 1500 1000 500 Annual precipitation (mm) W E

  11. 2. Western North America – 41ºN – latitude of Salt Lake City permanent snow and ice NIVAL snowbeds SUB-NIVAL 4000 3500 3000 2500 2000 1500 1000 500 0 wet meadows dry grassland open fell-field ALPINE Populus tremuloides Abies lasiocarpa Picea engelmannii Pinus albicaulis Juniperus spp. Pinus longaeva SUB-ALPINE Picea-Abies-Pseudotsuga forest MONTANE FOOTHILLS mixed coniferous forest Tsuga-Thuja-Picea-Abies-Sequoia-Sequoiadendron Altitude (m)  Temperature Pinus woodland steppe PLAINS temperate forest (Quercus) open woodland /savannah temperate rainforest prairie desert 3000 2000 1500 1000 200 Annual precipitation (mm) W E

  12. Tree-Line in the Americas

  13. Alpine zone Extent of the Alpine Zone in the Americas N S • snow-line • tree-line Extent of alpine zone (tree-line to snow-line)

  14. Richness of Alpines Global 10 000 – 15 000 species (6% world's flora) Europe 2 500 species (20% Europe's flora) N America 1 200 – 1 500 species (9% N American flora) S America ? 1 000 species (?% S American flora)

  15. General Comparisons of Alpines in the Americas

  16. Alpine Species Richness Patterns

  17. Changes in Alpine Richness with Increasing Latitude and Altitude N America ~ 5 species decrease per 1º latitude increase S America ~ 3 species decrease per 1º latitude increase If we allow for differences in total richness, then percentage decrease in alpine richness with increasing latitude is about the same, 1.7% in North, 1.5% in South America. Number of endemics decreases with increasing latitude in N America but not in S America – ? differences in history. Also a decrease in species richness with increasing altitude N ~30 species decrease per 100 m altitude S ~18 species decrease per 100 m altitude

  18. SPECIES IN COMMON (15) Anemone multifida Gentiana prostrata Koenigia islandica Cerastium arvense Phleum alpinum + 4 other grasses 6 species of Carex

  19. GENERA IN COMMON (29)

  20. FAMILIES IN COMMON (16)

  21. PRIMARILY NORTH AMERICAN FAMILIES(10)

  22. PRIMARILY SOUTH AMERICAN FAMILIES (12)

  23. POSSIBLE FLORISTIC HISTORY • Little direct fossil evidence – very few studies • Higher frequency of endemics in South America • Species ranges and genetic diversity generally smaller in S America Beringia plants Ice-sheets in North Circum-arctic plants Andean plants Basin plants Steppe plants Ice-sheets in West and South Ice-free mountain areas Circum-antarctic plants

  24. THREATS TO SURVIVAL AND CONSERVATION Live in a period of rapid environmental change – climate, land-use, atmospheric nitrogen, plant introductions, mountain developments. Provide potential threats to the survival of alpines. ++ = high threat + = some threat - = no likely threat

  25. FINAL COMMENTS • Both continents have wonderful, attractive, interesting, and very different floras. • Striking differences between the two continents in terms of tree-line and extent of alpine zone, probably due to the major differences in wind severity. • Many areas remain to be explored and documented. Great amount to be discovered in both North and South America. • Much remains to be brought in cultivation. • American alpines, like alpines elsewhere, are threatened by impacts of 'global change', especially global warming, atmospheric nitrogen deposition, and loss of habitat.

  26. Acknowledgements Peter Erskine Phil & Gwen Phillips Marcela Ferreyra Loren Russell Martin & Anna Sheader Loraine Yeatts Cathy Jenks

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