Human impact on plant populations and ecosystems. VL Environmental Ecology SUREMA 2004

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1 Human impact on plant populations and ecosystems VL Environmental Ecology SUREMA 2004 Prof. Dr. Isabell Hensen,, MLU Institute of Geobotany and Botanical Garden

2 Introduction Human impact on plant populations and ecosystems Species extinction Habitat fragmentation The problems of small populations Genetic diversity and reproductive success Conservation biology In-situ and ex-situ conservation Restoration Ecology Global warming

going into a decline from the stresses imposed

3 Introduction Environmental sustainability:the ability of the environment to function without going into a decline from the stresses imposed by human society on natural systems Raven & Berg 2001

4 Introduction Environmental sustainability? We are using non-renewable resources as if they were present in unlimited supplies!

5 Introduction Environmental sustainability? We are using renewable resources faster than they can be replenished naturally

6 Introduction Environmental sustainability? We are polluting the environment with toxic materials as if the capacity of the environment to absorb them was limitless

7 Introduction The Earth`s central problem Our numbers continue to grow despite Earth`s inability to support all of us!

8 Introduction We urgently have to look for solutions to meet immediate human needs while protecting the environment for a long term.

9 Species extinction Human impact on ecosystems

10 Species exinction Earth`s species diversity Species numbers are unevenly distributed across taxonomic groups with insects providing so far the greatest numbers

11 Species extinction Modern extinction rates are up to 1000 times higher than historic ones!

12 Species extinction Why do we need organisms? We depend on them for our survival!

13 Species extinction Why do we need organisms? Medicinal value of Catharanthus roseus for cancer therapy Agricultural value of the highly nutritive Psophocarpus tetragonolobus

14 Species extinction Apple pie and species extinction

15 Species extinction Insects apply essential ecosystem functions!

16 Species extinction The living world functions like a complex machine!

17 Habitat fragmentation Habitat destruction

greater Any given point within the fragment is on average closer to the edge

18 Habitat fragmentation Consequences of habitat fragmentation The total area remaining is smaller The proportion of edge in relation to the total area is greater Any given point within the fragment is on average closer to the edge than before Each fragment is more isolated from other fragments than before (Pullin 2002)

19 Habitat fragmentation Habitat fragmentation in Costa Rica: : (Forest cover per total area decreased from 67% to 17%) McDonald 2003

20 Habitat fragmentation Aggressive lianas hamper succession of tropical forest fragments!

21 Habitat fragmentation Edges of semi-natural grasslands are often influenced by agricultural practices

22 Small populations The problems of small populations Demographic problems: : random variation in birth and death rates Genetic problems: : random loss of genetic variation and inbreeding Environmental problems: : random variation in normal weather patterns Natural catastrophes such as fires, floods, volcanic eruptions etc.

23 Samll populations Dictamnus albus and Pulsatilla vulgaris, two rare and endangered species of Central Germany

24 Small populations SUREMA 2004 (Hensen Genetic diversity increases with population size! Dictamnus albus Pulsatilla vulgaris Genetic diversity Genetic diversity Log population size Log population size (Hensen & Oberprieler subm.)

25 Small populations Genetic drift: random fluctuation in allele frequency Page & Holmes 1998

Small populations Inbreeding depression: the reason for reduced plant fitness in small populations of Dictamnus albus? Component r P or is it pollinator limitation?

26 Small populations Inbreeding depression: the reason for reduced plant fitness in small populations of Dictamnus albus? Component r P or is it pollinator limitation? Height of flowering stem Number of flowers Number of fruits Fruit/flower rate Number of seeds Seed/fruit rate Mean mass of seeds Germination rate????

27 Small populations Extinction vortex Environmental variation Demographic problems Habitat destruction

28 Habitat degradation Small fragments of holm oak forests (Quercus ilex) ) in Southeastern Spain

Habitat degradation Variation of plant diversity and regeneration of Mediterranean holm oak along a grazing intensity gradient Diversity

29 Habitat degradation Variation of plant diversity and regeneration of Mediterranean holm oak along a grazing intensity gradient Diversity and presence of epiphytic lichens decrease with higher grazing intensity % Number of faeces pellets per m²

30 Habitat degradation Effects of grazing on sexual reproduction

31 Habitat degradation Mean acorn length and mean acorn mass of Quercus ilex decrease with increasing grazing intensity! Acorn length (mm) ,2 0,4 0,6 0,8 Grazing intensity per ha Acorn mass (g) 0,3 0,25 0,2 0,15 0,1 0, ,2 0,4 0,6 0,8 Grazing intensity per ha Cierjacks & Hensen in press

32 Habitat degradation Acorn abortion of Quercus ilex increases with higher grazing intensity! Proportion of aborted acorns (%) r=0.925** 0 0,2 0,4 0,6 0,8 Grazing animals per ha

Habitat degradation Polylepis australis, Rosaceae (Sierra de Cordoba/Argentina Argentina,, 2500 m NN) 60 50 Tussock (%) = 41.1 East aspect (x slope) = -0.81 b) 60 50 Exposed rock = 7.

33 Habitat degradation Polylepis australis, Rosaceae (Sierra de Cordoba/Argentina Argentina,, 2500 m NN) Tussock (%) = 41.1 East aspect (x slope) = b) Exposed rock = 7.97 East aspect (x slope) = Viability (%) a) Seed viability (%) Exposed rock due erosión (%) Tussock grassland (%) Renison et al. subm.

34 Conservation Biology Conservation Biology: scientific study of the development of ways how to protect biodiversity

35 Conservation Biology In-situ conservation: protected areas

36 Conservation Biology Ex-situ conservation: conservation of biodiversity in human-controlled settings

37 Conservation Biology In-situ conservation: protected areas

38 Conservation Biology Restoration ecology

39 Conservation Biology Temperate grasslands: prairie and steppe

40 Conservation Biology Temperate grasslands: prairie and steppe

41 Introduction The dust bowl 1937, Great Plains USA

42 Conservation Biology Prairie restoration in Wisconsin

43 Conservation Biology Prairie restoration in Wisconsin

44 Conservation Biology Prairie restoration in Wisconsin

45 Global warming Global warming Increase in CO 2 in the atmosphere, 1958 to 1998 Mean annual global temperature, 1960 to 1998 Raven & Berg 2001

46 Global warming Greenhouse effect Raven & Berg 2001

47 Global warming Ice cream in the tundra?

48 Global warming Effect of climate warming on precipitation Raven & Berg 2001

49 Global warming Effects of climate warming on water reserves Flooded coastal areas Floods Melting permafrost Raven & Berg 2001

50 Global warming Current and predicted biome distribution Gurevitch et al. 2002

51 Global warming Effect of global warming: disturbed ecosystem functions!

52 Global warming Solutions???

53 Global warming Conservación y Reforestación de las Sierras Grandes de Córdoba, Argentina

54 Global warming Fertilize the oceans?

55 Grimma 2002

56 Literature Further reading Frankham et al Conservation Genetics.. Cambridge. Gurevitch, Scheiner,, Fox The Ecology of Plants. Sunderland,, USA. Herrera & Pellmyr Plant-Animal Interactions. Blackwell. Page & Holmes Molecular Evolution. Oxford. Pullin Conservation Biology.. Cambridge. Raven,, P.H. & Berg, L.R Environment.. Orlando, USA.

16 Biological Resources

16 Biological Resources Overview of Chapter 16 Biological Diversity Extinction and Species Endangerment Endangered and Threatened Species Where and why species are endangered Conservation Biology Conservation