1. terrestrial systems Flashcards
what are the four mains aspects of ecology
- abundance
- distribution
- interactions
- patterns (phenology)
How to describe patterns
what and where questions
How to explain patterns
how and why questions
What are julian days and where are they used
Julian days are days of the year within the julian calendar (1-365 days) they are used in phenology graphs
what is phenology concerned with
cyclic, seasonal, periodic and time dependent patterns in nature (life cycles) related to environmental and climatic triggers and variations
what causes a phenology event
environmental trigger
what do phenology events cause
phenology events are growth stages, milestones
what is a shift in phenology
variations in climatic conditions eg higher temperatures early in the year
what is a biome
large biological community (all organisms) that has been shaped by its climate, they share common features due to the common climate.
How are biomes defined
by structure of the vegetation
10 major biomes
- Desert
- Grassland
- Island
- savanna
- Tropical Forest
- Temperate deciduous forest
- temperate evergreen forest
- tundra
- mountains
- wetlands
what are the major variables effecting biomes (7)
strongly determined by climate, temperature, precipitation, radiation and albedo, seasonality and soil and topography
what are the two variables that affect temperature
patterns with latitude and altidue this affects air temperature.
is there more change in longitude or altitude in air temperature
atilitide. 1 degree change for every 22m vertically vs 145km longitude
what is the relationship between precipitation and temperature with an example
this affects predominate vegetation structure therefore causing different biomes. example high p high t = evergreen forest. low p and high t = deserts
when looking at temperature (daily, monthly yearly) what three aspects must be considered that will effect the biome
mean, maxima and minima
what is seasonality and how does it affect biomes
seasonality is regular change that occurs in a calander year in relation to envrionmental variables eg precipitation dominance.
what is the effect of environmental change to a system
known as disturbance which can differ in scale and frequency, can change the composisiton of communities however systems usually return to orginal state after disturbance unless continous/ large
what are two methods of proxy climate change
- tree rings (width to record past climatic conditions)
2. ice cores (measure of gas bubbles co2 concentrations and other materials
what is the keeling curve
a station located in mauna loa (hawaii) that measures co2 concentrations since 1960s, showing rise in co2. sawtooth pattern reflects deciduous tree seasonality
4 main green house gas components
there are 43 gases CO2 N2O CH4 water vapour
in order of emissions list the 5 highest contributors of green house gases
- energy
- transport
- agriculture
- industry and products
- waste
how do we know the climate temp is increasing looking at temperatures
looking at anomiles divations from mean (since 1970s always been hotter)
how has rainfall anomalies changed since 1910
large events increasing causing higher risk of flooding
how does climate change relate to phenology
phenological shifts are early warning signs to climate change.
what are the 4 complex ecological changes occuring under climate change
- abundance change
- growing season change
- morphology shifts
- range shifts
what are GGD
growing degree days. quanity warmth above a baseline experienced over time by an organism, needed for development.
how is GGD calculated
average of daily max and min and compare to base temp or winter low
(Tmax + Tmin)/2 - Tbase
in the simplist of definitions, what is a plant community?
a distinct collection of plant species within a geographical unit that are distinguishable from other plant communities
simply; what is the debate surronding plant communities
are communties fundamental units that exist in nature or are humans imposing a sturcture onto nature that doesnt really exist?
who are the two key opinions in the plant communities debate and what are their views?
- clements (1937). communities are superogranisms, descrete and highly organised
- Gleason (1917,26)
vegetation is individualistic, chance and interactions shape distributions (no organisation)
what is the view currently held by ecologists about plant communities debate
boundaries are diffuse however communities exist and can be recognised in nature
describe the main vegetation patterns in australia
- rainforests in northern east coast (tropical hot)
- equcalypt forests on east coast (temperate wet)
- humic grasslands in arid centre (hot dry)
- acia shurbs edge of grasslands
- savannah north
describe main climate, geology and vegetation of sydney basin
geomorphology: cumberland plain surrounded by plateau to north and south and blue moutains to west.
climate: gradiant from east of west of wet to dry to wet again.
geology and soil: majority of the basin is wianamatta shale with hawsbury sandstone (low nutrient with woodlands and forests)
how has vegetation in the sydney basin changed since colonisation
widespread land clearing in the cumberland plain resulting in fragmented vegetation communities. while some national parks exists it is not representative of all communities exisiting pre 1788.
what are the three classification schemes
- beadle and costin
- specht
- leaf texture of trees
main differences between schemes
- beadle and costin: based on structural plant formations needing botany to understand
- specht: simple repetitive system based on attributes, woody species easist to classify however difficlut for non woody types
- Leaf texture:
not as complex, based on leaf type (hard or soft) and understory leaf type
what can make a map out of date
disturbance, clearance or new classifications of species
what is specific leaf area
a measure of leaf thickness (leaf area/mass)
what are the difference between mesomorphic and sclerophyllous leaves
mesomorphic leaves are thin soft horizonal found in humid tropical envrionments
sclerophyllous leaves are hard thick pendulous and small found in harsher abotic environments
difference between open and closed forest
closed light is blocked from canopy
open forests are seperated and light can penetrate into understory
what is Braun-Blanquet Scale
measure of cover and abundance (%) for species
mapping process (6 steps)
- field survey and plot samples of plant composition and structure
- classification of site to community type
- correlation to environmental variables
- spaital model of community distribution
- accuracy assessment
- aerial photographs
main patterns in forests australia
- ecualpty edge
- semi arid acacia
- inland mainly not forested (some woodlands)
global rainforest distribution
equitorial region
what is a rainforest
closed canopy forest of mesomorphic species
what makes gondwanan rainforests distinctive
high conservation value, more than 200 rare or threatended species
and many relic taxa.
There are more than 50 reserves of the forest, the rest has been cleared making this area very fragmented
when was the canopy discovered
exploration began in 1980s, new study dendronautics
temperate rainforests global distribuTIon
restircted, non equitorial usually in coastal regions
distinct Tarkine
largest single remaining temperate rainforest in AUS, provides habitat for over 60 rare and endagered specoes and has high diversity. while 80% protected from logging only 5% is protected by mining due to aus law therefore conservation debate
greater blue mountains heritage site
represents adaptability and evolution post gondawana isolation and protecting relic species eg wollemia
approx economic value of one single tree per year
~$50 000 by providing utility of co2 reduction, energy saving, air quaility imporve, increase property vlaue and strom water reduction
what is a sustainable harvest
harvest in surplus. need to know the carrying capacity of the envrionment and population ecology
wahat is MSY maximum sustainable yeild
max amount harvested that can be sustainable (assuming no flucation in envrionemnt) this is 1/2 carrying capacity or equilibium point where by after harvest populatiosn will return to carrying capacity
what is a resource collapse
where harvests exceed MSY and wild populations are depleted
what is Bioeconomic theory
harvest for maximal social and economic benefit
tradgey of commons
Using resources from the commons has benefits for the individual but the costs are shared communally.
short term profit there’s no incentive to conserve. finite resources are overexploited. therefore needs to regulate
pine tree invasion
most occur near plantation sites however these wildings produce progency. where the seed was dropped resulted in outcome (farmlands eated)
what is a bioregion
large geographically distinct area of land with common geolomorpholigical, climatic and ecological features
issue with national reserve systems
not all bioregions are represented meaning they are not all preserved in these areas of reserves.
where do eucalypt forests mainly occur in aus
allow the coasts in temperature areas
how is a woodland classified
by the height of the dominant vegetation ie eucalpyt forests
what is a eucalpyt open forest and where do they occur
usually in low rainfall areas, understorey of shurbs and grasses.
what are the great western woodlands
occur in WA, biome of temperature woodlands that is a global biodiversity hotspot with many endemic species
what is a basal area
measurement of a tree. measured at ‘breast height’ ~ 1.3 m above ground.
what is a stand basal area
area sum of basal areas of trees in a stand (an indentified mapped area of forest). m2
what can stand basal area be used for
to classify an open or closed woodland forest. (eg 2 m2/ha is open vs 30 m2/ha closed)
furthermore can be used to estimate tree biomass. the greater the basal area the greater the biomass. carbon storage is also calculated from this biomass.
how is climate change impacting fire ecology
climate change causes hotter and drier conditions resuilting in larger and more intense mega fires. these mega fires cannot be prevented with prescribed burning
why are australian trees suseptible to fire?
low nutrient soils, lower rainfall, higher heat -> sclerophyll trees -> lignin doesnt break down = more accumulation litter (fuel)
plus
areas of exposed wind =
high fire suseptilibilty
what is a fire interval
length of time between one fire and the previous
what is a fire period
the fire interval averaged over a number of fires eg 4 fires in 20 years = fire period of 5
what is a fire interval and fire period important
defines what vegetaion and organisms will live there. recovery and reproduction of a species.
what is a fire tolerant interval
the time ebtween a species reaching reproductive maturity and senescence when reproduction stops. if a fire occurs before or after these stages it may prevent recovery of the cpmmunity. each species has a different fire tolerant interval
natural fire interval vary between biomes. which is the most frequent fire cycles vs the longest globally and in aus
globally:
tropical forests lowest frequency ~1000 yrs
grasslands highest ~1 yr.
aus: savanahsn in north highest ~ 1 yr. tasmania lowest ~ 10
but varies everywhere. higher frequency in north compared to south.
what incourgases the intensity of a fire
high winds, high temps, low humidity incourages high spread.
how can fire intensity be inferred post fire
2 methods:
- char height. the highest blackened levas attatched to ta tree
- leaf scorch height. where the leavs in the tree canpoy are killed.
with growing intensity = higher heights
what shape are fires usually
elliptical from point source. the maximum intensity is at the head while the flanks at the sides and edges are at lower intensity (variation)
intensity of a a fire equation
intensity = heat yeild of fuel * weigth of fuel * rate of forward spread
how does topograohy affect fire intensity
upslope more contact area = travles quciker. also wind speed will indensify fire.
fires can have positive effects for plants. list some and some reasons
increase productivity, flowering, germination, release of seed, estbalishment
(higher nurtients, decreased herbivory, removal of competation)
3 ways plants can regrow after a fire
- lignotuber (underground nodules on roots)
- coppicing (growth from the shoot)
- suckering (shoots from the root in various places)
what are the two types of plant responses to fire
- non sprouters AKA obligate seeders (die if scorched will release seeds)
- sprouters (will reshoot after scorched)
how do obligate seeders and sprouters differ in location
spouters occur in areas frequently burned while obligate occur in areas rarely burned
difference between woodlands and forests
woodlands = simple diversity, shorter and space. forests = taller, more diversity, higher rainfall
what are the types of grasses
all from the smae family poaceace
there are true grasses (cereals, bamboo, turf) and informa; grasses (sedges and rushes)
how are grass species idensitified
throught anatomy, differences in tiller (stem), leaf blade, spike etc
what is a spike
reproductive part of the grass.
what is the difference between c3 and c4 plants
difference in photosythetic pathway of the species. c4 is more efficenct in fixing carbon as it uses pepc while c3 just uses rubisco.
how is the difference for c3 and c4 grasses important for climate change
c4 are more efficenct with water use. they can occur in higher temps with lower quality feed and high light.
this means it may favour climate chnage comapred to c3 which usually reqauires cooler climates with high moisture
what is digestability in reference to grasses
measure of the quality of grass (energy content of feed) related to the amount of energy needed for an animal - usually livestock. it is a measure of the proportion of grass utilised by an animal. it influences the speed of digestion (higher quality = quciker)
what is a crude protien
related to digestability of grasses. as crude protein increases so do livestock performance.
how has grasses changed since colonisation
dominant grasses would have varied with alt and rainfall however favoured regular burning and light grazing pressure. -> change to more resiliant to grazing, livestock requirements
how does greater plant diversity effect productibity
greater primary productivity. more productive spieces present at higher diversity.
= more stability
results from global nurtient enrichment experiment
more nurtients = fwer species, less light but more biomass
why are long term studies of grasslands important
change is only observed after decades.
what are rangelands
in arid and semi arid areas west of WSB. native pasture grazing.
issues of cattle grazing for native species
- tampling desturction of habitat and soil compaction
- over grazing, loss of shelther and predation increase
- competetion for food and selective grazing impact reuges
impact of study removal cattle from regions
historic grazing has effected recovery. more rodents, more mammals, not affected reptiles
what is the tree boundary of an apline region
region where trees cannot grow due to climatic limit (high altitudes
how has the aus government justified hard hooved livestock and feral animals in the apline regions
they claim they reduce biomass therefore reduce thr risk fo fires however long term monitoring has shown there is no difference in grazed and ungrazed areas fire damage.
how does leaf colour shape and orientation effect temperature
horzontal and vertical = different soloar radiation. in hotter areas (ie arid) leaves will be pendulous or verticle and litter colour
