Populations and Sustainability

Draw a graph to show population growth of a species and describe each phase

A. Lag phase - only a few individuals, acclimatising to habitat, rate of reproduction, and thus growth, is low

B. Log phase - resources are plentiful, good conditions, reproduction happens quickly and it exceeds mortality rate, rapid population rise

C. Stationary phase - carrying capacity of habitat reached - habitat can’t support a larger population, rates of reproduction and mortality equal, population size stable or slight fluctuation with the seasons

What are limiting factors? Give some examples

F

What are the two types of strategists?

k-Strategists: population determined by carrying capacity of habitat, and limiting factors affect growth, e.g. mammals

• low reproductive rate

• slow development

• late reproductive age

• long lifespan

• large body mass

r-Strategist: population so fast carrying capacity exceeded before limiting factors have an effect, once succeeded, lack of resources means a stop to reproduction and even death, e.g. insects

• high reproductive rate

• quick development

• young reproductive age

• short lifespan

• small body mass

Draw a graph to show population growth in r-strategist species

Much like the modern economic cycle of the West…

Draw and describe the population between predators and prey

What are examples of general conservation strategies?

• Protected areas like National Parks

• Legal protection to endangered species

• Conservation ex situ in zoos or botanic gardens

What are specific management strategies?

• Raise carrying capacity by providing extra food

• Restrict dispersal of individuals using fences

• Vaccination against disease

• Control predators and poachers

• Preserve habitats by preventing pollution or disruption

• More individuals to enlarge populations

• Encourage natural dispersion of individuals between fragmented habitats using dispersal corridors

Why should habitats conserved?

• Ethical responsibility

• Provide a value food sources

• May be beneficial to medicine

• Predators/pests can act as natural control agents

• Insects pollinate crops

• Ecotourism and recreation

How can small-scale timber production be managed?

• Coppicing: stem of a deciduous tree is cut close to the ground, new shoots grow and narrow into mature stems, after cutting them off, new shoots grow, and so on

• Pollarding: cutting the stem higher up to prevent deer eating them

• Rotational coppicing: wood divided into section and only one section cut each year, good for biodiversity as stops succession where growth of trees blocks light, reducing species below

How can large-scale timber production be managed?

• Harvested trees replaced with new ones

• Selective cutting: only largest, most valuable trees removed

• Only plant particular species where they will grown well

• Control of pests

• Position trees at optimal position apart, reducing competition

How are fish stocks managed?

• Fishing quotas - avoids overfishing

• Bigger holes in nets - immature fish can escape, grow and reproduce

• Restrict time of year when fishing can happen - protect breeding season

• Fish farming - maintains supply and protects wild species (fisheries or aquaculture which involves cultivation of fish under controlled conditions)

Examples of successful conservation

Terai Region, Nepal:

• Forests in the region have struggled with agriculture expansion, modern crop-varieties, farm animal grazing and over-exploitation

• WWF and Nepalese govt have started a scheme to balance conservation and the stakes of the local community

• Community forest initiatives where locals can exploit the forest but must also look after it

• Forest corridors between parks, allowing dispersal of animals like tigers

• Crackdown on poaching and illegal felling

• Waterholes constructed

• Endangered species monitored

• Invasive species eradicated

Maasai Mara, Kenya:

• 2005: conservancies formed to generate tourist income, payment for wildlife conservation schemes, tourism operators pay conservancies an income proportional to conserved land, positive social and conservational outcomes

Give four examples of environmentally sensitive ecosystems affected by human activity

Galapagos Islands: many native species, but increased demand for marine products and tourism has caused habitat disturbances and introduction of species (e.g. cats) has led to local species being outcompeted, Charles Darwin Research Station set up a marine reserve, areas undisturbed, introduced species culled

Antarctic: protected areas, fishing evenly distributed to prevent overfishing of krill, albatrosses and petrels threatened by long line fishing, done at night/weighted lines reduce risk

Lake District: conservation workers remove invasive species, more varied planting and felling patterns, limestone pavements legally protected, seasonal restrictions along cliffs on walking when birds are nesting, farmers paid to maintain hay meadows

Snowdonia National Park: drainage ditches caused by farming blocked by hay bales, conifers planted as cash crops dry out moorland so branches laid to block drainage ditches, slowing water flow and keeping land moist