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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 Nepal Himalayas • Seven taxonomic groups including: trees, herbaceous plants, 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 Meadows and heath Elevation low TROPICAL FOREST Interpolated species richness Elevation Gradient Montane BETULA Coniferous Forest&…… Evergreen OAK-RHODODENDRON-Forest Deciduous Warm temperate-subtropical Forest 1000 m a.s.l.

  8. INTERPOLATION : ASSUMING ALL SPECIES ARE PRESNET IN ALL 100M INTERVALS BETWEEN LOWER AND UPPER ELEVATION LIMIT This gives total number of species 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. Elevation and Human population density: focus 200 - 3100 outlier

  12. 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.

  13. r= ns r= 0.81 r= 0.025 r= -0.55 r= -0.62 r= -0.62 r= -0.70 r= -0.58

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

  15. Area result outliers

  16. Correlations between log (species richness) and log (area) in km 2 for target taxa between 200-3100 m a.s.l.

  17. Cause Effect High human population High biodiversity Climate Temperature

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

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

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

  21. Cause Effect High human population High biodiversity reduced forest cover Related to Intermediate disturbance hypothesis

  22. More tree richness at low forest cover !

  23. 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

  24. Thank you for your attention Lopped oak forest rich in species

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

  26. Biodiversity and disturbance species richness Increasing disturbance

  27. 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

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

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

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