6.6 Populations Flashcards
describe the lag phase
few individuals acclimatise to their habitat. rate of reproduction and growth in population is slow
describe the log phase
resources are plentiful and the conditions are good. pop size increases rapidly and reproduction rate exceeds mortality rate
describe the carrying capacity
this is when the habitat cannot support a larger population. reproduction and mortality rate is equal. limiting factors come into play
what are the two types of limiting factors
density dependant
density indépendant
describe density independent factors
act strongly regardless of pop size e.g low temp will kill same proportion of individuals regardless of pop size
describe density independent factors
factor influences pop more strongly as pop size increases e.g availability of food water and light, when pop size increases there are higher levels of parasitism and predation
describe k strategists and examples of them
pop size is determined by carrying capacity- limiting factors have significant effects
birds, larger mammals (humans, elephants, lions, larger plants)
define characteristics of k strategists
- low reproduction rate
-slow development
-late reproductive rate
-long lifespan
-large body mass
describe r strategists and examples of them
pop size exceeds carrying capacity before limiting factors have effect
after carrying capacity is exceeded there are not enough resources for survival and reproduction so build up of waste products may poison species “boom and bust”
mice, insects, spiders, weeds
define characteristics of r strategists
-high reproductive rate
-quick development
-young reproductive rate
-short life span
-small body mass
identify the differences between r and k strategists
r strategist species tend to have rapid reproduction rate and quick pop growth so they can colonise disturbed ground before k strategists
K are more likely to be members of a climax community because the r are likely to have reached carrying capacity and dispersed to other habitats
describe the predator and prey effect on pop size
1- predator pop gets bigger, more prey is eaten
2- prey pop gets smaller, less food for predators
3-less food so predator pop gets smaller
4-less predators, less prey eaten so pop increases
5- more prey, predator pop increases and cycle repeats
define interspecific competition
competition between individuals of different species
define infraspecific competition
competition between two individuals of the same species
define the competitive exclusion principle
more overlap between two species niches’ results in more intense competition. If 2 species have the same niche, one is outcompeted by the other and dies out or becomes extinct in that habitat
example of competitive exclusion principle
2 species of paramecium grown both separately and together
when together, competition for food and after 20 days one species died out and the other increased and was left as the only remaining species
define conservation
maintenance of biodiversity including diversity between species, genetic diversity within species and maintenance of a variety of habitats and ecosystems
define preservation
maintenance of habitats and ecosystems in their present condition minimising human impact
why is a conservation a dynamic process
needs constant adaptation to changes within the ecosystem
what does conservation involve
-maintaining genetic diversity
-maintainance of habitats
-managing areas of land
-taking steps to encourage new habitats
-removing animals to captivity
-growing plants in cultivation
-reclamation of damaged or destroyed ecosystems
what does preservation involve
-protecting ecosystems so they are kept exactly as they are
-nothing removed from a preserved area
-visitation is limited
describe reasons organisms become extinct
H-habitat destruction
I- invasive species
P-predation
P-pollution
O-overharvesting
why can human population threaten biodiversity
-overexploitation of wild populations for food
-habitat disruption and fragmentations as result of intensive agricultural practices/pollution/widespread building
-species introduced to an ecosystem by humans that outcompete other native species
describe conservation strategies
-raise carrying capacity by providing extra food
-more individuals to enlarge populations or encourage natural dispersion of individuals by developing dispersal corridors of appropriate habitat
-restrict dispersal of individuals by fencing
-control predators and poachers
-vaccinate individuals against disease
-preserve habitats by preventing pollution or disruption or intervene to restrict the process of succession
describe economic reasons for conservation
-natural ecosystems provide services such as regulation of atmosphere and climate, formation and fertilisation of soil, recycling nutrients, growing of timber, food and fuel
- natural environments are a valuable source of beneficial organisms (medicinal drugs)
-natural predators of pests can act as biological control agents
-ecotourism
describe ethical reasons for conservation
-species become extinct as a result of human action
-humans have responsibility to maintain species, ecosystems and habitats for future generations
-all organisms have a right to survive and live in the way which they have become adapted
describe social reasons for conservation
-people enjoy visiting wild places and observing wild life
-wellbeing: physical, intellectual and emotional health
how did the terai region make resource more sustainable
by creating forest corridors, counteracting poachers and illegal felling, introducing biogas plants and wood efficient stoves, constructing waterholes, monitoring endangered species and eradicating invasive species
how did the Maasai mara make resource more sustainable
by creating conservancies that allow limited grazing and tourism opportunities to co exist
similarities between terai region and Maasai mara
both strategies adopted acknowledged the importance of local people and work with them and both have conservation with development aspects
differences between the terai region and Maasai mara
Maasai are responsible for large areas of land, where as indigenous terai just work on land owned by government
what are the positive consequences of the Terai region
forests provide local people with a sustainable source of fuel, animal feed, food, building materials, agricultural and household tools, as well as medicines. Tiger population appears to be increasing.
what are the negative consequences of the terai region
increasing tiger populations might tempt back poachers
what are the positive consequences in the Maasai region
positive partnerships between conservancies and tourism organisations. sustainable farming and tourism opportunities for locals
what are the negative consequences in the Maasai region
land owners are forced to move their livestock out of the conservancies during the tourist season and can be forced to resettle elsewhere
what are the main threats to native species on the Galapagos islands
habitat disturbance, over exploitation of resource, effects of introduced species
how do goats pose a problem to conservation on the Galapagos islands
goats feed on Galapagos rock-purslane, a species unique to the islands, trample and feed upon giant tortoises food supply and disrupt their nesting sites. On northern Isabella island, the goat has also transformed the forest into grassland, leading to soil erosion.
how does the management of the marine reserve around the Galapagos islands provide a model for effective conservation
it shows how local stakeholders can work together to sustainably manage a resource
how is protection of krill important to the antarctic ecosystem
because they are a key component of a large number of food chains and a number of their predators are unable to adapt to find krill elsewhere if their numbers are low
describe factors which work against conservation
-human population growth
-climate change
-pollution
-growth in ecotourism
-continued exploitation of natural resources
describe strategies which help in conservation
-limit size of local population
-control local industry
-pollution levels and exploitation of natural resources
-control number of tourists and where they can go in ecosystem
describe conflict in the Lake District
-spruce and pine in conifer plantations support limited biodiversity
-invasive species escaped from gardens and spread into woodland out competing native species
-rare ferns grow well in the fissures of limestone pavement and rare butterflies thrive in this habitat
describe solutions to conflict in the Lake District
-recent initiatives have generated more varied planting and felling patterns, giving a mosaic of smaller strands of different aged trees
-physically removed by conservation workers
-the pavement is legally protected through the limestone pavement orders
describe conflict in snowdonia
-farmers dig open drainage ditches to dry the land- rain flows quickly through habitat- increases flood risk
-conifers are planted as cash crops- this dries out the moorland as the trees absorb water, roads have to be built to carry wood away, compacting the land
-old heather burns easily and so accidental fires can be a high risk
describe solution to conflict in snowdonia
-drainage ditches can be blocked by hay bales
-when trees are cut down, branches are used to block drainage ditches to slow water flow and keep the land moist
-burning controlled fired before heather gets too old and dry to prevent damage to habitat
describe main threats to woodlands
-easily converted to agricultural land
-development (housing)
-logging
-pollution- acid rain from coal burning
-global warming- may change rainfall patterns
describe uses of timber
-building construction
-fencing
-fuel
-paper
-furniture
describe small scale production
pollarding- cut trees high up
coppacing- cut lower almost at stump
describe large scale production
clear felling- destroys habitat, causes erosion of soil and nutrient loss
selective felling- cuts out largest, most valuable trees and replant them so habitat is broadly unaffected
describe the process of coppicing
-trunk cut close to ground level
-several new shoots grow from cut surface
-protect young shoots from grazers
-process repeated after certain time
-broadleaved species
-rotational species
-can be repeated indefinitely
describe benefits of coppicing
-new stems grow more rapidly than saplings
-lifespan of tree extended
-provides variety of light levels
-fewer large trees means more light for smaller plants
-provides variety of habitats
-roots prevent soil erosion
what do fisheries need to do to manage fish stock sustainably
-maintain fish populations at their carrying capacity
-fishing quotas
-minimum catch size net sizes
what are the pros of aquaculture
-stable supply of fish
-relief for wild aquatic animals
-protection of habitats
-mitigation of the endangered species problem
-local income source
-employment opportunities
-feed growing world population
what are the cons of aquaculture
-use of antibiotics
-use of growth hormones
-genetic manipulation
-water pollution
-problems if farm fish escape and breed with wild fish
-regarded to as unnatural
-conditions in fish farms are poor
-ecosystems are altered
