Man’s activities- Vietnam war and effects on the landscape; effects on species diversity?

Chapt. 55: Conservation Biology

MAN EXTINCTION!!

Hawaii-- 4.5 billion yrs of evolution + 2,000 yrs of extinction = 39 bird species (7 geese, 9 flightless, eagle, hawk,

3 owls, 2 crows, honeyeater, 15 finches) nowextinct

New Zealand-- 1,000 yrs = 13 flightless birds extinct

N. Amer. And Australia-- large mammals, birds, reptiles extirpated in 20k yrs (13 of 15 genera)

Why Worry?? Do we really need all those species??

See “Hotspot” web site of Conservation International(http://eelink.net/EndSpp/)Where are the Hotspots?Approx. how many species are involved?What kinds of species are involved?

Benefits of Biodiversity-Human ecology- on top of the energy pyramid (food and

resource use); man within his ecosystem; life w/o other species??

e.g. Medicines (50% of all prescription), soil erosion, recycling, pest control, pollination, hydrology

Collapse of any ecosystem can result in harmful effects on humans! Man’s impact already causing discomfort and even death on a world scale. (examples?- introduced exotics in S. Africa, Fig. 55.5)

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Does diversity result if greater stability, resistance, or resiliency?Stability- constancy, no change (two forces involved)

Also: (1) Resistance- degree of resistance to perturbation(2) Resiliency after change- capability for returning

quickly to the original (pre-perturbed state);I.e. successional restoration

(3) Susceptibility- likelihood of perturbance

Conservation Biology-- the study of biological diversity and how to preserve it.

Ecosystems, communities, populations-- which have more or less of theabove? ( Read. Assign: “Case Histories”)

Threatened, Endangered, and Extinct!!

What are the causes??

EXTINCTION!!Small populations = increased Susceptibility, less Resistance

and Resilience (“islands” and fragmentation)Causes:

(1) Exploitation-- e.g hunting(2) Inroduced Species-- pests, competition, predation (vs. endemics!!)(3) Impacts on Mutualists-- coevolved species, e.g honey creepers and

Lobelia of Hawaii (Fig. 55.8)

(4) Habitat Destruction and Fragmentation— agriculture, forestry (clear cutting), agroforestry

e.g.Co-opted species-- favored for production and use byhumans (30% of all global terrestrial production)generated by loss of, and fragmentation of, natural habitats (see Table 55.1 and Fig. 55.10).

**How does the ratio of area-to-perimeter change with decreasing area of a patch (assume a circular patch)?

(1) Patch size may not be large enough to accommodate a species natural home range.

(2) Forced movement from patch-to-patch can have serious reper-cussion, e.g. predation, foraging inefficiency.

(3) Patch size, shape, and spacing also important (Reading Assn. “Case Histories: Landscape Structure)

Patch (island?) Size and Edge Effects-- what are the effects of reducing patch size on species diversity, extinction, etc.? (e.g. eastern Songbirds and destruction of tropical/subtropical habitats)

e.g.Edge effects (patch shape) = ratio of patch perimeter (P) to patch

area can be used to quantify and compare patch shape (S),e.g. for a circle,

S = P / 2Agreater values than 1 indicate more elongatepatches with greater perimeter(edge) per unit area.

The US Forest Service has changed clear-cut policy from long,rectangular strips to large, more rounded cuts, to much smaller cuts in tightly spaced clusters. Why??(See satellite photos below)

Why are the amounts of edge and area both important?

What effects might this have on different species?-Elk and deer-small mammals-songbirds-birds of prey-vegetation-livestock-insects

Spacing and patch (island) density effects-- ratio of time inside patch away from edge effects to time between patches.

Fractal geometry and measurement scale-- one species ruler is another’s yardstick, e.g. barnacles vs. eagles (Fig 18.7 Read. Assn.). What effect does measurement scale have on computation of P?

Metapopulations-- habitat fragmentation can result in many smallsubpopulations instead of one large population, e.g. small mammals in Kansas prairie. Remembergenetic drift, emigration, & bottleneck?

What are the expected effects of the above on standard parameters of population biology and island biogeography (species equilibrium;

immigration, emigration and extinction rates)??

Patch Size and Population Size-- Island Biogeography on another scale??

“Edge Effects” and fractals

Habitat (Forest) Decline-- European temperate deciduous forests,Patch size and edge effects

Habitat (Forest) Decline-- USA

Thus, other organisms are important for our own survival!!Recovery of Biodiversity-- How?? Threatened, endangered, and

extinct and species

Possiblities: (1) Exploitation-

commercial interests such as hunting for food and other products (pets, medicines, adornment, domestication

(2) Habitat destruction-commercial logging, air/soil pollution, development (wetlands), urbanization, desertfication

(3) Habitat isolation- metapopulations, fragmentation, dispersal, biotic effects(predator/prey, home range, food competition)

(4) Coevolution-removal of keystone species leads to another specie’sextinction

Costa Rica

Sumatra

“FRAGMENTATION”“Patch Size &“Edge Effects”

Methods of Recovery: -Preservation- design of natural preserves (size, fragmentation),

captivity (zoos and parks), e.g. Quanacaste, CR-Change in demographics- b, d, and r (e.g. bird nests of eastern

songbirds, Kirtland’s warbler and Jack Pine,Fig 55.15-16)

-Species introductions- hard lessons learned, matching micrositerequirements, genetic consequences (founder effects and drift) to new and parent popuation

-Protection of keystone(umbrella/nurse) species (African elephant)- concept of “relative community importance”, mutualisms (figs and palms of Peruvian forests)

-Captive propagation (peregrines and condors)- maintenance, cost, reintroduction!! (molecular preservation?) (Fig. 55.18)

Where should recovery be focused?? Endemism, species richness, Fig. 55.22 (four categories of priority). HOT SPOTS !!

Conservation Priorities- “Hot Spots”

CONSERVATIONHOT SPOTS!!

Restoration Ecology- can entire ecosystems be restored?e.g.Guanacaste National Park in Costa Rica Wetlands in San Diego

Great Difficulties!! Still experimental.

Economics of our Natural Resources ($$)- What is the commercial value of a lizard, bird, forest, pond, panoramic view, clean air, butterfly farms, cancer cures (yew tree), recreation?

$$$$$$$$$$$$$$$

Longrange value!!