D4.2 Stability and Change

Sustainable ecosystem

supports itself without ouside influences

Example of a sustinable ecosystem

Amazon rainforest

• 14 million years ago a mrine lake

• has evolved into a rainforest with river

• developed trasnipartion, plants animals

Requiermnets of sustainability

• supply of energy → sun for photysyntehis which can then pass down trophic levels

• nutrient recycling → nitrogen or carbon cycle

• genetic diveristy → species need genetic diverity in case something happes so they wont all die

• climatic variables within tolerance limits → if not habitat loss, food loss and death

Tipping point of Amazon rainforest

Tipping point: a point at which the forest wont be able to sustain itself

• Last 60 years - massive deforestation

• 17% of land clered

• Amazon rainforest controls its tempratures and rainfall as trsnpiration allows for a lot of water vapour to be produced and with evaporation comes a cooling effect whcih influces airflow and rainfall

• SInce deforestation → lower rainfall and higehr trempatures

• We dont know when the tipping point will be reached

Mesocosm

creates a living enviroenment for organisms

• can use open task but preferedd loosely sealed or with plastic vessels so energy can enter and exit but matter cannot

Keystone specie

• organism important for biodiveristy of an ecosystem

• not the number but its role its important

• to estbalish a keystone specie a removal experiment can be performed to look at the ecosytem without the species

• removal can lead to trophic cascade and ecosystem collapse

Sustainable harvesting

rate of harvsting is lower than the rate of replacement

Sustainable havesting of Chilean Sea Bass

• gained popularit in 1990’s → consumer demand → overfishing

• Decline in population + a technique was used using hundreds of hooks on one line causing death of many marine birds

• Reguations came in 2000 inclduing: monitoring of population, regulation on how much fish can be caugh, at what age, whe. Limitations on sea birds, change in fishing season and an inspector from an organization needs to be on boardr when catching the fish to ensure its regulated

• Zero illegal fishiing now

Sustainable harbesting of black cherry trees

• Red wood - for furniture and cabinet

• Once clear cut for farming

• Now FSC implemented sleective logging → trees selected to be cut down creating light gaps where new seeds can be disperesd and grow into new trees

Sustainable agriculture

• Soil erosion - due to no crops to hold soil together whcih is exposed to rain and wind. Topsoil should be rich in nutrints. Cover crops can be implanted to keep the soil togetehr with roots

• Leaching of nutrients - irrigation + rain lead to leaching of nutiensts into water sources creating pollution. Can be solved by applying less ferilzier and iirgiation at optimal times

• Fertilizer supply - costly plus neergy expensive - leumes can be planyed which have nitoegn fixing bacteria in roots

• Pollution from agrochemicals: fertilzier run off causing pollution in water sources due to overuse

• Carbon footprint: amount of greensouse gases generated by an activity: machienry by petroleum, fertilizers which can contain petroleum, tarsnport of crops, land clerence

Eutrophication process

• Ferilizers (nitrogen and phosphours) are soluble in water for plant absorption but sometimes not all is absorbed and runoff water causes leaching of fertilziers into water sources

• The ferilizer will stimulate excessive growth of alage mostly on top of the water source as thats where sunlight is the greatest

• This will cause a continuous thick layer of algae to form which wont allow sunlight to penetrate thorugh the water and reach the other aquatic plants causing their death

• Aerobic bacteria will then strat deocmposing the dead algea but they hvae biochemical oxygen demand

• The dissolved oxygen will then become depleted causing also the death of aerobic bacteria, fish and other marirne organisms

Biomagnification

build up of toxins or damaging chemicals over trophic levels in food chain

Bioaccumulation

buildi up of a toxic chemical in a single organism

Biomaginification of mercury

• caused by burning of coal - relased into atmosphere and oceans

• microgorinaism convert it to methyl mercury which moves up the food chain

• humans are exposed to high mercury conetnt by eating fish which can cause neurological damage

Biomagnification of DDT

• synthetic insecticide

• was used against mosquitos as it was effective, cheap and long lasting

• It was massed spayed from aircrafts entering water sources

• It was absorbed by phytoplantkton

• moved up trophic levels and was accumulated in bald eagles

• affected tehir calcium metabolism

• they produced thin shelled eggs that could not withstand the mass of the parent during incubation

• very little young bald eagles

Plastic is

not biodegrdable

Microplastic

smaller than 5 mm

includes macropkastic thats been broken down or small partciles used in hand cleaners and beauty products

Macroplastic

• larger than 5 mm

• includes plastic bottles, cans, bags, containers

Risk of plastic in oceans

• sea turtles eat plastic bags thinking its jellyfish

• albatrosses feed plastcics to chicks

• many animals ingest microplastic accidnetally causing buidl up of plastic in intestines and stomach

• plastic fishing nets often lost by fihsers which is a death trap for many marine animals

Rewilding

restoring and protecting an area

Rewilding includes:

• reintorduction of apex preadtors (carnovores at top of food chain) and key stone species

• creating wildlife corridors to conect habitats

• minimal human intervention

Example of rewilding

Hinewai Reserve in New Zeland

• 109 hectares of farmland

• extended to 1250 hectares

• removal of invasive trees and species

• regenarte the wildlife

• still in progress

Succesion

change over time in species that live in an area due to abiotic or biotic factors

Why can succesion be triggered

• fire

• volcanic eruption

• disease

Primary succesion

• begins on new land with no life

• no soil

• low biomass

• lichen and moss begin to grown on volcanic rocks

Secondary succesion

• after a catstrophic event

• soil presnet

• seeds and roots present

• biomass higher

Primary succesion process

• pioneer species - moss or lcihen begin to grow creating soil

• increase in genetic biodveristy

• increase in size of plants

• increase in primary prdouction

• incraee in nutrint recycling

• formation of more complex food webs

→ climax community

Cyclical succesion

• cyclical pattern that emegres over a long period of time

Wood pasture

• open garssland where herbivores graze

• thorny thicket grows → grow as herbivores wont eat them

• tree begins to grow inside thorny tricket → protectetd from animals

• tree casts shade of thicket leading to its death

• dies of old age the tree

• open grassland again → cycle repeats

Climax community

most stable

can be interapted by humans → removing forest for livestock or drianing wetlands for developemntt