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Congruence between species richness and human population density: reconciliation or conflict?

Congruence between species richness and human population density: reconciliation or conflict?. Ole R VETAAS Unifob – Global, University of Bergen, 5015 Bergen, Norway, M. CHRISTENSEN University of Copenhagen, Forest and Landscape, Denmark.

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Congruence between species richness and human population density: reconciliation or conflict?

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  1. Congruence between species richness and human population density: reconciliation or conflict? Ole R VETAAS Unifob – Global, University of Bergen, 5015 Bergen, Norway, M. CHRISTENSEN University of Copenhagen, Forest and Landscape, Denmark

  2. Congruence between species richness and human population density • Human action is often claimed to be the main cause behind habitat loss and biodiversity reduction. CONTRADICTION to (?) • Large parts of the globe have enhanced biodiversity, and at the same time these areas have a high density of people

  3. AREA , ORGANISMS, and RESEARCH QUESTION • The present study analyses species richness along an elevational gradient IN THE NEPAL Himalayas • Seven taxonomic groups including: trees, ferns, cryptogams, and fungi • WHAT kind of organism has this correspondence, and why?

  4. INDIA TIBET

  5. Cause Effect ? High Biodiversity High human population Obscured Many Biological options for exploitation Human settlements Species rich cultural landscapes Human settlements

  6. Research question 1 Which organism has a correlation between human population density and species richness along the total elevation gradient

  7. high Ice & rock Alpine Tundra Elevation low TROPICAL FOREST Northern Coniferous Forest Arctic Tundra Interpolated species richness Elevation Gradient Montane BETULA Coniferous Forest&…… Evergreen OAK-RHODODENDRON-Forest Deciduous Warm temperate-subtropical Forest 1000 m a.s.l. TROPICAL FOREST

  8. INTERPOLATION : ASSUMING ALL SPECIES ARE PRESNET IN ALL 100M INTERVALS BETWEEN LOWER AND UPPER ELEVATION LIMIT This gives total number of specie in all different elevation bands from 100 m to 6000 m a.s.l.

  9. Research question 1 Which organism has a correlation between human population density and species richness along the total elevation gradient

  10. Scale and patterns • This large scale pattern may in part be ascribed to the fact that very few people live in very unproductive species-poor areas, such as deserts, sub-arctic-biomes, or high mountains. • The correspondence between species richness and human density may not be evident at shorter spatial extents such as along an human populated elevation gradient.

  11. Research Question 2: Which organism has correlation between richness and human population along the populated part of the gradient 200 - 3100 m a.s.l.

  12. Cause effect High biodiversity High human population AREA of elevation zones Species area relationships

  13. Area result outliers

  14. Pearson correlation between log (species richness) of different groups and log (area) in km 2

  15. Obscured Cause and Effect High human population High biodiversity Climate Environmental temperature

  16. Forest and people • Forest cover is influenced by human density • Forest cover may influence species richness

  17. humna densuty forest density in % M a.s.l.

  18. log-HUMAN-POPULATION DENSITY and log-FOREST-COVER

  19. Obscured Cause and Effect High human population High biodiversity reduced forest cover Related to Intermediate disturbance hypothesis

  20. More tree species at low forest cover !

  21. conclusion • Forest cover predicts tree specie richness • Forest cover is determined by climate at higher elevation and human density at lower elevation • Thus people may have a positive impact on tree diversity • Management implication: a moderate reduction of total forest cover may enhance richness rather than reduce it

  22. Thank you for your attention

  23. Biodiversity and disturbance species richness Increasing disturbance

  24. Theory Intermediate disturbance hypothesis • Hutchnison (1951), Grime (1973b), and Connell (1978), has suggested that there is higher chance for many species to coexist, when a community or landscape is moderately disturbed. • This tenet is well accepted, although disturbance is difficult to define and measure

  25. Disturbance definition • Many different definitions • Grime: disturbance = reduced or destructed biomass • Browsing, Grazing, Fire or other biomass outtake are regarded as disturbance

  26. Biodiversity; biomass and disturbance species richness increasing biomass increasing disturbance

  27. Exploit the dominant species • This may be done by: • Selective logging in a forest • Lopping or pollarding of canopy trees • Browsing by large mammals

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