Population Ecology (Chapter 52)

Population Ecology Campbell and Reece, Chapter 53Principles of Biology I (Biology 113) Notes, 2014Ours is a singular case; no other population of large animals has likely ever sustained so much growth for so long. Reece et al. p. 1268 http://www.worldometers.info/world-population/As the human population reaches 9-10 billion in the mid twenty-first century, which probably exceeds carrying capacity, and will be followed by a downsizing (Barrett and Odum, 2000; Lutz, Sanderson, and Scherboy, 2001), it is imperative that future generations understand Goodlands (1995) definition of sustainability as maintaining natural capital

quote from Odum and Barrett (2004) in Clements, D.R. and Shrestha, A. (eds.). 2004. New Dimensions in Agroecology. The Haworth Press, Binghamton, NY. 553 pp.

Are population biology or science & technology sufficient?

Does a Christian worldview offer greater depth and breadth?

Distinctives of a Christian Environmental Ethic (after Bouma-Prediger and Stephenson in Living the Good Life on Gods Good Earth)

1. God is a community of love (a Trinity) who takes on human flesh to redeem our world (John 1:14, John 3:16)

THE WORLD: ONLY HOPE FOR SAVING THE WORLD IS OURSELVES2. God creates all things and makes a covenant with creation (Gen. 1, Gen. 6-9)

THE WORLD: WE AND THE OTHER CREATURES ARE COSMIC ORPHANS3. God is distinct from creation but also intimately sustains it (Ps. 104)

THE WORLD: THE ENVIRONMENT IS SUSTAINED BY NATURAL PROCESSES4. All creation worships God (Ps. 148)

THE WORLD: CREATION HAS NO HIGHER PURPOSE, IT EXISTS FOR ITSELF5. Humans are to rule the earth according to Gods justice (Gen. 1:26-28)

THE WORLD: HUMANS HAVE NO PARTICULAR ROLE OTHER THAN TRYING TO FIX UP THE MESS6. As earthly creatures we are called to serve the earth (Gen. 2:15)

THE WORLD: WILLING TO SERVE THE EARTH ONLY AS LONG AS IT SERVES USThe Blaauw Eco ForestGenerous family donates funds for TWU to purchase portion of Glen Valley foresthttp://www.twu.ca/news/2013/042-land-donation.htmlA Rocha Canada Christians in Conservation

If my people, who are called by my name, will humble themselves and pray and seek my face and turn from their wicked ways, then will I hear from heaven and will forgive their sin and will heal their land.

2 Chronicles 7:14 (NIV)

http://

HYPERLINK "http://vimeo.com/72450691" vimeo.com/72450691

Excerpts from Kingfishers Fire by Peter Harris, founder of A Rocha International:

Markku Kostamo knew that visibility was poor on December mornings in rural British Columbia, but even so he was sure that last night he had left only seven cattle in his pasture. As he rubbed his eyes against the early gloom, he could see that there were at least forty there now, and they were a far more mixed bunch than his beloved Scottish Highlands. Heavy with the early dew on their hides, they were chewing philosophically and didnt seem in any hurry to go anywhere. Even so, Markku saw he had no alternative but to stumble out of the farmhouse and make a new plan for the

morning. One quick look at the animals and a couple of phone calls

later, he had his explanation.

Markku and his wife Leah run the farm in Canada as an A Rocha centre and among their neighbours is a cattle feed-lot. It was their entire stock that had made a break for freedom, quite wisely heading for the good organic pasture of the A Rocha meadows.

As an A Rocha experience, it was only too familiar and disorientating. When the story of the first field study centre was told in the pages of Under the Bright Wings fifteen years ago, there was only one project to show for ten years of local involvement in the Algarve one cow in the meadow as it were. At the time of writing, work is going on in seventeen countries, and as just one indicator of what that means I was recently told that over fifty thousand children were involved last year. Another seven national groups have joined in during the two years it has taken to write this book and more seem to be arriving all the time. It seems that God has opened the gates of our own particular meadow, and at times it causes us to rub our eyes in amazement.

Population dynamics

Population changes can be tracked by observing births, deaths ,immigration

and emigration Also need to be able to measure the population size

For mobile organisms, the mark and recapture method is often used (e.g.,for Hectors dolphins)

Formula: N = MC/R

N = population

M = marked animals in 1st sample C = total captured in 2nd sampleR = number recapturedCharacteristics of populations Dispersion (Fig. 52.4): clumped, uniform or random What causes these? Which would you expect to be most common?

Demographics: Age structure, sex ratio, mortality rates etc. Some organisms can regulate sex ratio e.g. two spotted spider mites Age structure: can indicate population growth or decline

Life history strategies How an organism allocates limited resources to survival, reproduction, migration and other life history characteristics

semelparous (Fig. 53.12): salmon life history iteroparous: cedar tree strategies must account for the cost reproductionWhy do populations of snowshoe hares cycle in the Yukon? Hypothesis I: food shortage hypothesis Hypothesis II: predation hypothesis Feeding experiment cycle continued even with abundant food Predation causes cycling, but complexworking together with food shortage shortage reduced reproduction Often there is a trade-off between number and size of offspring (cannot have both large and many) e.g., weedy plants vs long-lived plants (Fig. 53.14) Different types of organisms exhibit different different survivorship curves (Fig. 52.6)

Type I: most mortality late in life organisms with most mortality late in life organisms with good care of offspring e.g. humans Type II: constant mortality e.g. rodents, annual plants Type III: many offspring, but little or no parental care e.g. many invertebrates Population growth models exponential: dN/dt = rmaxN (rate of change in population N, with intrinsic rate of increase rmax )

e.g., human population growth Is there a human carrying capacity? population growth with a carrying capacity = logistic model

logistic (Fig. 53.9): dN/dt = rmaxN((K-N)/K) (K = carrying capacity) some real populations exhibit logistic growth, but must be careful in applying a theoretical model to real situation e.g. fisheriesPopulation density and population growth populations strongly influenced by density tend to stay near K_ e.g., territorial nesting birds, plants at high densities populations with density independent influences tend to fluctuate, and seldom reach K e.g. crabs, insects Global carrying capacity

No ecological question is more important than the future size of the human

population Reece et al. p. 1271 Footprint = aggregate land and water area appropriated by

a given nation to produce the resources it consumes and absorb the waste it generates (or calculated for other units e.g., individuals)

Global human footprint too big for the earth

See: http://www.footprintnetwork.org/gfn_sub.php?con

HYPERLINK "http://www.footprintnetwork.org/gfn_sub.php?content=global_footprint" \t "_parent" tent=global_footprintNumerous websites where you can calculate your own ecological footprint, e.g.,http://www.myfootprint.org/http://www.mec.ca/Main/content_text.jsp?page=ecofootprint&FOLDER%3C%3Efolder_id=2534374302883396PAGE 1