Sinclair Macaulay Lecture 11112006

Slide1: 

Lessons for ecology, conservation and society from the Serengeti Anthony R.E. Sinclair Centre for Biodiversity Research University of British Columbia, Canada

Slide2: 

Dr. Simon Mduma Head of TAWIRI & the Serengeti Biodiversity Progam The Macaulay Institute Frankfurt Zoological Society NSERC, Canada National Geographic Society Wildlife Conservation Society THANK YOU

Slide3: 

THE TEAM Simon Mduma Stephen Makacha Ally Nkwabi John Mchetto Anne Sinclair John Fryxell Ray Hilborn Roy Turkington Kris Metzger and indirectly Markus Borner Simon Thirgood and many others

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Species are being lost at unprecedented rates. How much can we lose before the ecosystems in which we live become unsustainable? Species exist within a matrix of other species and are subject to the effects of their environment We must understand how the whole system behaves- lack of understanding could lead to surprise, inappropriate management, or even system collapse THE WORLD PROBLEM

Slide5: 

- therefore, one must understand important properties of ecosystems to apply - effective management - effective conservation THE NEED

Changes in Ecosystems can lead to unexpected outcomes: 

Changes in Ecosystems can lead to unexpected outcomes Flathead Lake, Montana Opossum shrimp added to provide extra food for Kokanee Salmon Bald eagles

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Flathead lake, Montana Spencer et al. 1991 BioScience

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Unexpected events occur because of complex interactions. Illustrated by events in Serengeti, Tanzania

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Rift valley Rift valley Isuria Scarp Ol Doinyo Lengai Meru 4565 Ketumbaine 2942 Gelai 2962 Olduvai gorge The Serengeti Ecosystem Salai plains Serengeti plains Loita plains From Grant Hopcraft KENYA TANZANIA

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SERENGETI IS COMPOSED OF TREELESS PLAINS

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..AND SAVANNA WOODLANDS

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Wildebeest is the dominant species

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Wildebeest migration patterns TANZANIA KENYA

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Kris Metzger The reason for dry season migration 1200 400

Serengeti Wildebeest Population outbreak – the event that changed everything – to understand it we must go back a century: 

Serengeti Wildebeest Population outbreak – the event that changed everything – to understand it we must go back a century 0 300 600 900 1200 1500 1800 1950 1960 1970 1980 1990 2000 Population Size (x 1000)

The Great Rinderpest: 

The Great Rinderpest The Epizootic of 1889 Ethiopia to Cape by 1896 Die-off of cattle and other ruminants 95% These include African buffalo Wildebeest yearling disease present up to 1963 THIS IS THE PERTURBATION THAT UNDERLIES OUR UNDERSTANDING OF THIS SYSTEM

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Complex events that followed the wildebeest increase - Grass fires: between 1920s and 1960s 80-90% of savanna was burnt each dry season

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Grass fires prevent tree regeneration below 2 m height

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Repeated burning prevents regeneration and produces a distorted age structure of old trees

% Acacia tree canopy cover drops rapidly in the 1960s: 

% Acacia tree canopy cover drops rapidly in the 1960s H.Dublin 1986

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Northern Serengeti, Mara triangle 1944 Photo Syd Downey

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1983

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Wildebeest grazing reduces grass fuel and area burnt

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SERENGETI AREA BURNT IN DRY SEASON

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Increase in wildebeest causes decrease in burning

Complex interactions of wildebeest and the environment: 

Complex interactions of wildebeest and the environment The extent of grass fires is determined by the degree of grazing imposed by wildebeest ….this had consequences on savanna trees

Slide29: 

1980 1986 2003 1991 Savanna

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Martin and Osa Johnson 1928

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Osa Johnson filming from plane 1933

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NYARABORO FROM EMAKAT 1928 1982 2003

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SERENGETI TREE DENSITY Instantaneous rate of change in tree density negative 1920s-1960s, then increases rapidly in 1980s, 1990s following wildebeest

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Serengeti woodland lion numbers increase in the 1990s Wildebeest x 1000 Lion data from C. Packer

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Decrease in most resident prey

Disturbance and multiple states: 

Disturbance and multiple states Ecosystems are continually being disturbed weather events human harvesting invasions of species predation Disturbance can cause a change of state

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Disturbance changes ecosystems – which do not always return to the original state afterwards The role of elephants in Serengeti

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Elephants knock down mature trees and blamed for tree decline

Trees and elephant predation: 

Trees and elephant predation 1970s – fire rather than elephant shown to be the cause of decline (Norton-Griffiths work in 1970s) Elephant play another role by feeding on seedlings

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Dublin observed elephants removing almost all seedlings - They hold the system in a grassland state

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Removal of elephants in Serengeti by ivory poachers in 1980s but not in Mara…..

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SERENGETI ELEPHANT POACHING IVORY BAN

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..resulting in much food for elephants in the 1990s and 2000s in Serengeti but not the Mara (wildebeest in both)

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KENYA TANZANIA SERENGETI - MARA 2005 -hence ecosystems can have more than one state under the same conditions

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Tibetan yak

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Tibetan grasslands near Naqu

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MONGOLIA – Brandt’s vole outbreaks

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CHANGE IN STATE: swans on Lake Ellesmere, New Zealand

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Disturbance and Ecosystem Processes What goes wrong if we ignore ecosystems? Their processes for ecosystem functioning For example Hydrology, flux and storage Biodiversity and Stability (resilience)

Slide52: 

Saline upwelling in Western Australia

Biodiversity and stability: 

Biodiversity and stability species diversity and community resilience e.g. Australian Eucalypt woodlands

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Original closed eucalypt woodland

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Degraded eucalypt woodland

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Drawings Frank Knight Noisy miners reduce or exclude….. …white-plumed honeyeaters and other species in degraded Eucalypt woodland Loss of bird diversity in Australian woodland

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Psyllid outbreaks in isolated trees of farmland

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Eucalypt dieback – eastern Australia Psyllid insect outbreaks cause dieback in exposed trees disruption of intact forest causes biodiversity loss and ecosystem disfunction

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Disturbance events take a long time To understand ecosystems we must understand the long-term events. History is important Rinderpest – the ecological event in 1889 that changed the course of human history in Africa. It decimated human populations and allowed the colonization of Africa The ecological effects are still seen in Serengeti today

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The Great Rinderpest epizootic removed Buffalo long-term change 1890-2003 Poaching Data from Sinclair & Mduma

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Acacia tree density 1880-1980 The great rinderpest

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Disturbance and history THE IVORY TRADE 1840s – 1890s

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TIPPU TIP The great slave trader of eastern Africa - 1860s to 1890s

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EAST AFRICAN IVORY EXPORTS Data from C. Spinage 1973

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The Ivory trade Poaching SERENGETI ELEPHANT CITES Ivory ban

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Ivory hunting – affected the vegetation in Protected areas such as Tsavo (Kenya) and Chobe (Botswana), and altered the long-term course of conservation in Africa. It also decimated human populations and prevented human advancement

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Therefore, - ecosystems are always changing, they do not return to the same state long-term consequences e.g. Scotland - e.g. New Zealand

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LESSONS FOR SOCIETY: THE FUNCTION OF MIGRATION Migration allows use of ephemeral resources on the plains and so larger populations than if they were resident. This rule applies to all migrations

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SAHEL Traditional Human migrations in the Sahel follow rain

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Boreholes have been sunk in the Sahel since the 1960s to present. Sedentary life style has resulted in overgrazing

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Photo A. de Vos 1975 .. and repeated famines. MALI FAMINE 1973

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MALI – The Green Polygon 1973 demonstrates overgrazing not drought

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The ranch boundary

The role of Protected Areas: 

The role of Protected Areas The Green Polygon illustrates the need for baselines Protected Areas act as such ecological baselines to provide insight for human ecosystems BUT Ecosystems are continually evolving and do not return to where they began - Protected areas will not stay as they are currently

Take home message: 

Take home message Conservation has to focus on ecosystems - they are complex, have long time scales and multiple states - they are subject to disturbance which can change state - human disturbance can be monitored by reference to Protected Areas - ecosystems are continually changing Current protection strategy is not addressing this issue - we need to find a new way to accommodate change