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Lessons for ecology, conservation and society from the Serengeti Anthony R.E. Sinclair Centre for Biodiversity Research University of British Columbia, Canada THANK YOU Dr. Simon Mduma Head of TAWIRI & the Serengeti Biodiversity Progam The Macaulay Institute Frankfurt Zoological Society NSERC, Canada National Geographic Society Wildlife Conservation Society 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 THE WORLD PROBLEM 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 behaveslack of understanding could lead to surprise, inappropriate management, or even system collapse THE NEED - therefore, one must understand important properties of ecosystems to apply - effective management - effective conservation Changes in Ecosystems can lead to unexpected outcomes Flathead Lake, Montana Opossum shrimp added to provide extra food for Kokanee Salmon Bald eagles Flathead lake, Montana Bald Eagles x 7 160 Kokanee x 1000 140 Opossum shrimp Abundance Index 120 100 80 60 40 20 0 1978 1980 Spencer et al. 1991 BioScience 1982 1984 1986 1988 1990 Unexpected events occur because of complex interactions. Illustrated by events in Serengeti, Tanzania The Serengeti Ecosystem Loita plains Serengeti plains KENYA Gelai Salai 2962 plains Ol Doinyo Lengai Ketumbaine TANZANIA 2942 Meru 4565 From Grant Hopcraft SERENGETI IS COMPOSED OF TREELESS PLAINS ..AND SAVANNA WOODLANDS Wildebeest is the dominant species Wildebeest migration patterns TANZANIA KENYA The reason for dry season migration Mean Annual Precipitation 1200 Kris Metzger 400 SNP Boundary Mean Annual Precipitation (cm) 36 - 46 46 - 55 55 - 64 64 - 73 73 - 83 83 - 92 92 - 101 101 - 111 111 - 120 No Data 40 0 40 80 Kilometers Population Size (x 1000) Serengeti Wildebeest Population outbreak – the event that changed everything – to understand it we must go back a century 1800 1500 1200 900 600 300 0 1950 1960 1970 1980 1990 2000 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 % with Antibodies Incidence ofRinderpest Rinderpest in Serengeti 100 Wildebeest 80 60 40 Buffalo 20 0 1955 1960 1965 Years 1970 Complex events that followed the wildebeest increase - Grass fires: between 1920s and 1960s 80-90% of savanna was burnt each dry season Grass fires prevent tree regeneration below 2 m height Repeated burning prevents regeneration and produces a distorted age structure of old trees % Acacia Canopy % Acacia tree canopy cover drops rapidly in the 1960s H.Dublin 1986 30 25 20 15 10 5 0 1940 1960 1980 Year 2000 Northern Serengeti, Mara triangle 1944 Photo Syd Downey 1983 Wildebeest grazing reduces grass fuel and area burnt % Area Burnt SERENGETI AREA BURNT IN DRY SEASON 100 90 80 70 60 50 40 30 20 10 0 1960 1970 1980 1990 2000 Increase in wildebeest causes decrease in burning 100 % area burnt 80 60 40 20 0 0 500 1000 Wildebeest number (thousands) 1500 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 1980 1991 Savanna 1986 2003 Martin and Osa Johnson 1928 Osa Johnson filming from plane 1933 NYARABORO FROM EMAKAT 1982 1928 2003 SERENGETI TREE DENSITY rate of change in trees 0.6 Instantaneous rate of change in tree density negative 1920s-1960s, then increases rapidly in 1980s, 1990s following wildebeest 0.5 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Lions use thickets to capture prey - more thicket improves success Serengeti woodland lion numbers increase in the 1990s lion 350 1600 wildebeest 1400 300 1200 Lion number 250 1000 200 800 150 600 100 400 50 200 0 1955 0 1960 1965 1970 Lion data from C. Packer 1975 1980 1985 1990 1995 2000 2005 Decrease in most resident prey 50,000 12,000 impala topi 10,000 40,000 Topi number Impala number 8,000 30,000 6,000 20,000 4,000 10,000 2,000 0 1970 0 1975 1980 1985 1990 1995 2000 2005 Disturbance and multiple states Ecosystems are continually being disturbed weather events human harvesting invasions of species predation Disturbance can cause a change of state Disturbance changes ecosystems – which do not always return to the original state afterwards The role of elephants in Serengeti Elephants knock down mature trees and blamed for tree decline 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 Dublin observed elephants removing almost all seedlings - They hold the system in a grassland state Removal of elephants in Serengeti by ivory poachers in 1980s but not in Mara….. SERENGETI ELEPHANT POACHING 3500 3000 IVORY BAN Number 2500 2000 1500 1000 500 0 1950 1960 1970 1980 1990 2000 2010 ..resulting in much food for elephants in the 1990s and 2000s in Serengeti but not the Mara (wildebeest in both) SERENGETI - MARA 2005 -hence ecosystems can have more than one state under the same conditions TANZANIA KENYA Tibetan yak Tibetan grasslands near Naqu MONGOLIA – Brandt’s vole outbreaks 12 Number of outbreaks 10 8 6 4 2 0 0 2000 4000 6000 Livestock equivalents 8000 10000 CHANGE IN STATE: swans on Lake Ellesmere, New Zealand 80000 Number of swans 70000 Wahine Storm, 1968 60000 50000 40000 30000 20000 10000 0 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 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) Saline upwelling in Western Australia Biodiversity and stability • species diversity and community resilience e.g. Australian Eucalypt woodlands Original closed eucalypt woodland Degraded eucalypt woodland Loss of bird diversity in Australian woodland Noisy miners reduce or exclude….. …white-plumed honeyeaters and other species in degraded Eucalypt woodland Drawings Frank Knight Psyllid outbreaks in isolated trees of farmland Psyllid insect outbreaks cause dieback in exposed trees -disruption of intact forest causes biodiversity loss and ecosystem disfunction Eucalypt dieback – eastern Australia Long time scales - The effects of history 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 Buffalo long-term change 1890-2003 Poaching 80000 Observed Reported 70000 Number 60000 50000 40000 The Great Rinderpest epizootic removed 30000 20000 10000 0 1890 1910 Data from Sinclair & Mduma 1930 1950 1970 1990 2010 Acacia tree density 1880-1980 6 Log Frequency 5 4 The great rinderpest 3 2 1 0 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 Disturbance and history THE IVORY TRADE 1840s – 1890s TIPPU TIP The great slave trader of eastern Africa - 1860s to 1890s EAST AFRICAN IVORY EXPORTS Ivory from Zanzibar Ivory from Khartoum 350 250 300 kg x 1000 kg x 1000 200 150 100 250 200 150 100 50 0 1840 50 1860 1880 Data from C. Spinage 1973 1900 1920 0 1840 1850 1860 1870 1880 1890 1900 SERENGETI ELEPHANT Poaching 3500 3000 counts reports CITES Ivory ban 2500 Number The Ivory trade 2000 1500 1000 500 0 1850 1900 1950 2000 The effects of history 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 Disturbance and history Therefore, - ecosystems are always changing, - they do not return to the same state - long-term consequences - e.g. Scotland - e.g. New Zealand 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 Traditional Human migrations in the Sahel follow rain SAHEL Boreholes have been sunk in the Sahel since the 1960s to present. Sedentary life style has resulted in overgrazing .. and repeated famines. MALI FAMINE 1973 Photo A. de Vos 1975 MALI – The Green Polygon 1973 demonstrates overgrazing not drought The ranch boundary 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 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