6.3.2 Populations and sustainability Flashcards
lag phase features
reproductive rate is slow
population size is small
takes time for dispersed individuals to find each other to mate
acclimatising to habitat
exponential phase (log) phase features
reproductive rate > death rate
pop. size increases rapidly
plenty of resources e.g. food (little competition)
little disease
few predators
no overcrowding
low environmental resistance (biotic and abiotic factors which limit population growth)
stationary phase features
reproductive rare = death rate (population size remains stable)
habitat cannot support larger population
reached carrying capacity (k)
carrying capacity definition
maximum number of individuals in a population supported by a particular habitat, determined by limiting factors
(k)
factors limiting population growth and effect
food water space light oxygen predation disease competition prevents populations from exceeding carrying capacity
r-strategists features
higher reproductive rate quicker development of population earlier reprodutive age shorter life span smaller body mass
k-strategists features
lower reproductive rate slower development later reproductive age longer life span large body mass
boom and busts method
some species exceed their carrying capacity due to rapid reproductive rate
once exceeded, insufficient resources to maintain the population and some die
death also caused by build up of waste products
predator-prey relationship
prey population increases when predator numbers are low and low environmental resistance with few limiting factors
more prey = more food for predators
population of predator increases after a long time
more prey eaten by predators = prey numbers decrease
less food for predators, fewer survive and predator numbers decrease
cycle repeats
prey population reach higher than predators
intraspecific competition features
within species
as environmental pressures increase (factors become limiting), competition increases
those best adapted survive, reproduce and pass on their genes (others die)
keeps stationary phase stable
interspecific competition features
between 2 or more different species
competitive exclusion (when differenr species populations grow together but one dies out due to competition)
or
species fill out slightly different niches (both persist populations grow much slower than when grown alone)
conservation definition
using nature in a sustainable manner
active management of ecosystem
preservation definition
protection of ecosystem from interference so that it remains in its original state
how increasing human populations threatened biodiversity
over-exploitation of wild populations for food
disrupting habitats with urbanisation and pollution
introduicng non-native spcies which competitively exclude native species
dynamic conservation definition
preservation of organisms and environments that are at risk from human activity
requires management and the creation of new habitats, which may need reclamation of land
ecosystem management strategies examples
reclaim ecosystem by reversing effects of human activity
raise carrying capacity by providing more food
introduce more individuals to enlarge populations
create corridors which connect fragmented habitats (allow species to move between them)
restrict dispersion of individuals by fencing
control predators and poachers
vaccinate individuals against disease
preservatipn of habitats by protecting against pollution or disruption or restrict succession (copping, grazing, etc.)
what is clear-felling and why it’s bad
clear-felling = completely cutting down all of the trees in an area
trees take up water from soil and stops soil erosion, which pollutes rivers
trees keep nutrient levels in balance in carbon and nitrogen cycle
clear-felling leads to opposite
sustainable production definition
harvesting in amounts which leave sufficient organisms to grow and replenish what has been harvested and can be carried on indefinitely
sustainable forestry features
woodland must be able to maintain its ecological function of biodiversity, climate, mineral and water cycles
local people should benefit from forest
balance is needed between making money, supplying plenty of wood and maintaining biodiversity
how to ensure each tree yields maximum amount of wood
control pests and pathogens
only plant tree species that grow well in an area
plant trees optimal distances apart to prevent too much competition for light, water and minerals
coppicing features
cuts tree trunk close to ground to encourage new, thinner stems to grow
thin wood can be used to furniture, firewood etc. but trees don’t die and no replanting needed
rotational coppicing method
woodland divided up and different sections coppicing on different years
coppicing can be done continuously to provide continuous supply of wood
standards = trees left uncoppiced and cut to produce larger timber for planks (more value)
pollarding definition
cutting higher up the tree to prevent herbivory
aquaculture features
breeding, rearing and harvesting of plants and animals in all types of water environments
restricts impact on oceanic fish stocks
fisheries economic feature
high economic value (sales + jobs)
marine stewardship council principles for sustainable management
overfishing must be avoided to stop extinction of species (aim to maintain population at its carrying capacity and only harvest excess numbers)
no permanent damage to local habitats (maintains structure and function of ecosystems)
always comply with local, national and global regulations (be flexible with these)
adv of aquaculture over capture fisheries
restricts impact of fishing on oceanic fish stocks
cheap and plentiful protien source for increasing human population
disadv of aquaculture over capture fisheries
populations susceptible to pests and pathogens
possible cause of pollution
what is a fishery
area of water where fish are caught for recreational or commercial purposes
Terai region of Nepal ecosystem
made up of marshy grasslands, savannah and forests
densely populated and home to endangered species (Bengal tiger, one-horned rhinoceros)
how humans use forests in Terai region of Nepal
locals depend on forests for: fuel animal feed/food building materials agricultural and household tools medicine
how sustainable forestry is being used in Terai region to maintain biodiversity and meeting needs of locals
WWF worked with Nepalese government
introduced community forestry initiatives (gives locals rights to exploit forest and responsibility to look after it) that:
-built forest corridors between national parks (essential for dispersal and survival of tigers)
-counteracts poachers and illegal felling
-developed forestry work, diversified on/off-farm activity, stimulated small credit and marketing schemes
introduced biogas plants and wood-efficient stoves to reduce demand for firewood
constructed waterholes
monitored endangered species
eradicating invasive species
Masai Mara ecosystem
savannah divided by Mara river close to river = grasslands + woodland further from river = open plains contains large mammals e.g. buffalo, elephants, black rhinos
how sustainable agriculture is being used in Terai
improve irrigation facilities (enhances crop production)
multiple cropping (more than one crop grown on a piece of land each growing season)
growth of nitrogen-fixing plants (legumes/pulses) to enhance fertility of soil
improving fertilisation techniques to enhance crop yields e.g. use manure
how humans use lands of Masai Mara
grazing of livestock (semi-nomadic farming)
trees for fuel
cultivation of crop (leads to reliance on fertilisers for effective crop growth)
ecotourism (raises funds but tourist movements contribute to soil erosion and habitat changes)
conservation and research (helps understand animal behaviour and physiology and monitor their populations)
balance examples in Masai Mara
human land uses in Masai Marai is incompatible with wildlife survival and vice versa e.g.
- elephants threaten trampling so land may be fenced, which -ve affects natural migration
- legal hunting culls excess animals but animal populations need to be constantly monitored to maintain natural balance in ecosystem
- livestock and migratory wildlife compete against each other for grass
- more homes and land for agriculture for increasing human population = lowered wildlife density
case studies for conservation
Masai Mara (Kenya) Terai region (Nepal)
case studies for preservation
Galapagos Islands
Antarctic
Lake District
Snowdonia National Park
habitat disturbance in Galapagos Islands
human population size increased
increased demand for water, energy, oil, sanitation services -> more waste and pollution produced
building and conversion of land for agriculture causes destruction and fragmentation of habitats
over-exploitation of resources in Galapagos Islands
fur traders and whaling boats killed 200,000 tortoises in less than 50 years
depletion of sea cucumber populations has drastic effect on underwater ecology
international market for shark fins led to 150000 shark deaths each year
effects on introduced species on Galapagos Islands
alien species can out-compete local species, eat them. destroy their habitat and bring disease e.g.
cats hunt lava lizard and young iguanas
goats trample and disrupt giant tortoise food supplies nesting sites
red quinine spreads rapidly due to wind-dispersed seeds and outcompete native trees, and shrubs so Galapagos petrel lost its nesting sites
managing effects of human activity on Galapagos Islands
search arriving boats and tourists for foreign species
introduction of natural predators of invasive species to eradicate them e.g. ladybird wiped out a scale insect that damaged plant communities
at least 36% of coastal zones designated “No-Take” areas, no extraction of resources allowed
Galapagos marine reserve provides model of how local stakeholders can work together for sustainable management of resources
how Antarctic is governed
countries with research stations there under Antarctic treaty actively protect the ecosystem and its biodiversity
krill in Antarctic
food for whales, seals, penguins
used for nutritional supplements and animal feed
new technology means large amounts of krill can be harvested very quickly and easily
natural predators cannot adapt/migrate to find krill elsewhere
krill fisheries should fish evenly across all areas
protected areas in Antarctic
Southern Ocean Whale Sanctuary covers summer feeding grounds for 80-90% of all whales
also International Whaling Commission moratorium
it is illegal to hunt and kill whales in these areas
whaling activity also monitored
albatrosses and petrels in Antarctic
threatened by pollution, hunting and poaching for eggs, habitat destruction and introduction of non-native predators, long-line fishing (long fishing line trailed behind fishing boats)
to reduce bird catches, boats use:
-bird-scaring lines and streamers
-weighted lines that sink quickly out of reach of birds
-lines at night to avoid bird feeding, breeding and nesting times
Lake District ecosystem and how it’s maintained
rich diversity of species and habitats (native woodland, wetland, chalk downland, hay meadows)
maintained by grazing causing deflected succession to prevent climax community of oak woodland
also financial incentives for farmers to reduce chemical use, safeguard hedges and take care of habitats
spruce and pine in conifer plantations in Lake District
support limited biodiversity
recent initiatives generated more varied planting and felling patterns
causing mosaic of smaller stands of different aged trees
invasive species escaped from gardens into Lake District
spread into woodland and outcompeting native species as dense canopy reduces light reaching woodland floor
roots produce toxic chemicals, stopping other plants growing
they are physically removed by conservation workers
limestone pavement in Lake District
solid blocks with fissures between them (unique habitat for rare ferns to grow and butterflies to thrive in)
legally protected through Limestone Pavement Orders
hay meadows in Lake District
occur in neutral grassland and support rich diversity of flowers and grasses
under threat due to preference of silage production
farmers paid to maintain hay meadows
silage production feature
use of artificial fertiliser and earlier cut
heathland in Lake District
could be under threat by overgrazing
financial incentives provided to farmers to prevent overgrazing
mire in Lake District
internationally scarce
under threat from burning, grazing and drainage
managed more sympathetically
some rewetted with artificially controlled water levels
grazing controlled
cliff, rock and scree communities in Lake District
easily damaged by climbers and walkers
seasonal restrictions on walking when birds nesting
walkers more educated to be more aware
paths well maintained to prevent people walking off paths
Snowdonia ecosystem
habitats: moorland, bogs, mountain
provide nesting sites for rare birds and home to rare butterflies
why and how paths are maintained in Snowdonia
so rare plants dont get trodden on
gutters take water from paths but get blocked by rubbish dropped by walkers
workers clear rubbish
why sheep and goat grazing reduced
sheep graze very low to ground so leaves landscape barren
National Park and farmers work together
gives rare plants better chance of survival
farmers digging open drainage ditches in Snowdonia
dries land but causes poor water quality in rivers and rain flows quickly through habitat, increasing flood risk
drainage ditches blocked by hay bales to reduce this
conifers planted in Snowdonia
cash crops but dries out moorland as trees absorb water
roads have to be built to carry wood away, compacting land
when trees cut down, branches used to block drainage ditched to slow water flow and keep land moist
old heathers in Snowdonia
burn easily and accidental fires at high risk
burning controlled fires before heathers gets too old and dry prevents such damage
why preservation of habitats is not viable sometimes
preservation leaves ecosystems untouched without human interference
sometimes not viable as area is damaged already and requires management and restoration
conserving lowland bogs
peat and vegetation of bog surface is wet as possible (less trees, block ditches)
control grazing (maintain biodiversity of peatland)
no/less burning (could lead to death of organisms from rare species)
measures in preventing permanent damage to oceans
fishing quotas mesh size species restriction days at sea penalties and sanctions monitoring and surveillance public education
difficulties in preventing permanent damage to oceans
area too large expense of monitoring monitoring hampered by weather false reporting of catches death of fish caught but not kept
