Unit 1: Ecology A: Human Impact and Conservation (Year 2)

examples of ecosystem

tropical rainforest and deserts like Kalahari Desert (60MYO)

components of ecosystem

are the living organisms, their physical environment, and the interactions between them. This includes abiotic factors like soil, water, and climate, as well as biotic factors such as plants, animals, and microorganisms.

• requires energy supply, nutrients recycling, genetic diversity, tolerable climate

tipping point

threshold when crossed leads to large irreversible change

tipping point example

amazon rainforest

20% deforested since 70s, becoming carbon source not sink

% change

100 x (final-initial)/initial

mesocosm

indoor experimental system

controlled environment

when is harvesting sustainable

harvest rate<replenishment rate

sustainable fishing examples

pacific cod: measured by capture-mark-release-recapture, echo sounders, fish catch analysis, quotas: limits on catch volumes, marine protected areas: designated zones to safeguard fish populations

sustainable harvesting example

silver top palm: only leaves harvested so can regrowwithout harming the plant.

max sustainable yield

largest catch of fish that can be sustained/time w/o stock drop

plastic

range of org synthetic materials that don’t degrade

micro vs macro plastic

micro: <1mm

macro: >1mm

plastic harm

ingestion: take space in stomach, damages

kills Laysan Albatross and sea turtles

rewilding

aims to restore degraded ecosystem to natural state

reintroduce keystone species (like wolves in Yellowstone)

reestablish connectivity of habitats thru wildlife corridors

manage ecosystem to reduce human impact

wildlife corridors

passageways that connect habitats, allowing wildlife to move freely between areas previously part of same habitat, thus enhancing genetic exchange and ecosystem resilience.

example for rewilding

hinewai reserve

new zealand

restored native vegetation

top four anthropogenic climate change causes

fossil fuels

agricultural practive

land use change

waste management

(methane/CO2)

ocean acidification coral effect

ocean acidification: more acidic bc more CO2 in air

CO2+H20=carbonic acid →dissociates to H+

H+CO3=hydrogen carbonate

reduced carbonate that is used for calcium carbonate exoskeleton coral building

coral bleaching

increased temp make coral expel zooxanthellae, lose color and food source

death → collapse of reef ecosystems

carbon sequestration

process of capturing/storing atmospheric CO2 to mitigate climate change

3 approaches of carbon sequestration

1. afforestation: establish forests in areas w no recent tree cover

2. reforestation: restoration of forests in previously forested areas

3. restoration of peat-forming wetlands: restoring of drained wetlands, peat forms when org matter isn’t fully decomposed bc of acidic/anaerobic conditions in waterlogged soils

positive feedback cycles effect

increase gw rate

positive feedback cycle: loss of ice and snow

white snow/ice reflects solar radiation

melting exposes darker surfaces that absorb more heat, leading to further warming and more ice melt.

positive feedback cycle: decomp of permafrost

As permafrost thaws, it releases greenhouse gases like carbon dioxide and methane, which further accelerate global warming and additional permafrost melting.

permafrost

soil that remains below freezing for >2 yrs storing C

positive feedback cycle: CO2 release from deep ocean

As ocean temperatures rise, the solubility of CO2 decreases, leading to the release of more carbon dioxide into the atmosphere, which enhances global warming and further warming of ocean waters.

positive feedback cycle: forest fires

As temperatures increase, forest fires become more frequent and intense, releasing stored carbon into the atmosphere, which contributes to further warming and more fires.

positive feedback cycle: boreal forest example

As the boreal forest warms due to climate change, it experiences increased tree mortality and insect outbreaks, which reduce forest cover and lead to more carbon release, further exacerbating warming.

stores CO2 undergroup bc low temp

at tipping point

rainfall and temp → droughts →decrease photosynthesis → more CO2

forest browning → increased wildfires releases stores carbon

landfast ice

forms on land from fresh water and snow

sea ice

forms from saltwater

emperor penguin

depend on sea ice to form breeding colonies and babies before they can swim

melt ice → die → risk of extinctiondue to climate change and loss of habitat. They are the only penguin species that breed during the harsh Antarctic winter.

ice floes

large pieces of floating sea ice that can break off from glaciers or ice shelves and drift in the ocean.

walruses dependency on ice floes

depend for food and resting

melting → move to beach → trampled young bc overcrowding and face increased competition for food.

nutrient upwelling

cold nutrient rich water rises from bottom to top of oceans

depends on ocean/wind current and stratification of H20 temp, changed bc of climate change

1. wind blows cross water surface

2. allows H20 below to rise up and nitrate/phosphate brought to phytoplankton on surface

3. phytoplankton growth

4. primary production → biodiversity

poleward shift

the movement of species and ecosystems towards the poles due to climate change, impacting biodiversity and ecological balance.

upslope shift example

birds in new guinea

migrating northward due to changing temperatures

less habitat

upslope shift

the movement of species and ecosystems to higher elevations as they adapt to warmer temperatures, often leading to habitat loss and changes in biodiversity.

example of poleward shift

N American trees

moving to higher elevations due to rising temperatures, resulting in altered ecosystems.

phenology

the study of the timing of seasonal events in nature, such as flowering, breeding, and migration, which are influenced by environmental changes.

variables that influence biological timing

photoperiods

temp patterns

photoperiod

length of time in day when org gets lights

biological events

flowering

migration

nesting

bud set (cessation of bud growth in deciduous plants)

bud burst (emergence of new leaves at beginning of growth season)

gw effect on reindeer and Arctic mourse-eared chickweed

northward reindeer migration synced w growth of chickweed

warming → earlier chickweed growth → less food for reindeer

gw effect on caterpillars and great tit

food source for birds during breeding season. Warming temperatures lead to earlier caterpillar emergence, potentially mismatching the timing for great tit chicks.

spruce bark beetles

insect pests that infest and kill spruce trees, leading to forest decline. Warmer temperatures can increase their population, exacerbating tree mortality.

tawny owl