final exam Flashcards
limits to plant distribution
(1) biogeographic
(2) physiological
(3) ecological limits
OR
historical –> does it arrive?
physiological –> can it germinate, grow, survive and reproduce?
biotic –> does it successfully compete and defend itself?
historical limits to plant distribution
is explained by millions of years of evolution in the context of factors such as climate change and continental drift
- explains coefficient of biotic similarity: “shared plant families” found between different regions
- floral kingdom
floral kingdom
a large geographic area with a relatively uniform composition of plant species
- floristic kingdoms: a high degree of family endemism
- floristic regions by a high degree of generic endemism
- floristic provinces by a high degree of species endemism
physiological limits to plant distribution
biomes show a strong latitudinal distribution
- reflects climate and soils/topography
- use climate to predict the vegetation zones/biomes (like in world veg)
1. Holdridge (triangle with potential evapotranspiration ratio, humidity provinces, and annual precipitation)
2. Whittaker (average temperature v annual precipitation)
Raunkier’s Classification
based on position of perennating (dormant) buds
(a) Phanerophytes: buds on exposed branch tips such as trees –> high in mild, moist environments
(b) Chamaeohytes: buds close to ground, protected by snow –> environments with snow cover
(c) Hemicryptophytes: buds at soil level, protected by dieback –> moist, temperate regions
(d) Cryptophytes: bulbs, rhizomes, corms, etc. protected by soil –> extreme cold or drought
(e) Therophytes: seeds –> deserts
biotic limits
competition (biotic limits) explains why species adapted to environmental extremes often occur only in stressful environments and not mesic environments , e.g., xerophytes occur only in deserts
plant communities
an assemblage of plant species that interact among themselves and with their environment within a space-time boundary
they have:
- a relatively consistent floristic composition
- uniform physiognomy
- a distribution that is characteristic of a particular habitat
california coastal prairie
characteristic species of this community include
- perennial bunch grasses
- danthonia
- festuca
- calamagrostis
- hordeum
- etc
organismic view
closed
- communities are clearly defined with sharp boundaries, indicator species, and distinct interactions
continuum concept
open
- ecotones tend to be “soft”, with overlap between communities across the ecotone
- distributions of plant species tend to be independent of one another
ecotones
- a transition area between two biological communities, where two communities meet and integrate
-are often caused by underlying environmental gradients
species interactions
can be random, positive, or negative
species interactions – positive
some clumping may be due to underlying pattern of resources, or it may reflect a positive association
- commensalism
- mutualism
plant growth simulation
- new plants develop while existing plants grow
- at some points, the plants have to fight for limited resources (water, light, soil)
- weak plants get dominated by strong ones and eventually die
- number of plants decreases with dominant plants growing
commensalism
an association between two organisms in which one benefits and the other derives neither benefit nor harm
-EPIPHYTES; occurs between small plants called epiphytes and the large tree branches on which they grow. depend on their hosts for structural support but do not derive nourishment from them or harm them in any way
- NURSE PLANT SYNDROME; takes place when plant species shelter seedlings, young and/or adult individuals of other species though their ontogeny
- HYDRAULIC REDISTRIBUTION (LIFT); the passive movement of water via roots from regions of wetter soil to regions of dryer soil, including the lifting of water from the deeper to shallower soil layers
mutualisms
-lichens
- mycorrhizae; fungi that have a symbiotic relationship with the roots of many plants, they enhance nutrient and water uptake of the host plant
- nitrogen-fixing bacteria
- pollination
- zoochory; the dispersal of plants (seeds) by animals , can be via getting stuck to fur or pooping it out lol
-myrmecophytes ; have structural adaptations to their rhizomes, leaves, and stems that provide ants with food and shelter, and in return ants assist them with nutrition, defense, and seed dispersal
species interactions - negative
- herbivory
- competition
herbivory
consumption of all or part of a plant by a consumer
- consumers: parasitic microbes or plants, grazing and browsing animals
considered negative because of biomass loss, however, may be positive when it involves pollination, dispersal, and germination
- 10 to 100% (seeds) lost to herbivory
- plants defenses against herbivory have an energetic cost
competition
results in mutually adverse effects to organisms that utilize a common resource in short supply
- ex. larrea and ambrosia in Mojave Desert
MECHANISM;
(1) resource based (passive) competition alters the availability of a limiting resource with greater or lesser effects on a given species –> Ambrosia affected more than Larrea
(2) non-resource based –> allelopathy –> the chemical inhibitor of one plant (or other organism) by another, due to the release into the environment of substances acting as germination or growth inhibitors
Ambrosia v. Larrea
Ambrosia root systems appear capable of detecting and avoiding other Ambrosia root systems, whereas Larrea roots inhibit Larrea and Ambrosia: activated charcoal suggests Larrea effect mediate by release of a chemical compound, but Ambrosia infraspecific interaction resource based
changes in communities
- disturbance –> sudden stochastic events
- succession –> 1-500 years
- climate change –> 1000’s years
- evolution –> millions of years
disturbances
accidentally injuries that reduce biomass and competitive ability
- processes leading to bare ground (unseats the occupier)
- can fall into two categories
(1) adaptations that allow a plant to resist disturbance (and keep their site)
(2) attributes that enhance the probability of colonizing a new microsite
intermediate disturbance hypothesis
- can support both k and r selected species if disturbance is not too several or too little
k- selected= exhibit logistic growth, have longer life spans , does well with low disturbance
r-selected= short life spans, exponential growth, does well with high disturbance
succession
directional cumulative change in species that occupy a given area through time
-types: primary, secondary, autogenic, allogenic, progressive, retrogressive, directional, cyclic
primary succession
occurs on land not previously vegetated
- barren area
- initiated due to a biological or any other external factors
- no soil, while primary succession starts
- pioneer species come from outside environment
- it takes more time to complete
secondary succession
occurs in previously vegetated areas that have been disturbed
- starts due to external factors only
- it starts where soil covers is already present
- pioneer species develop from existing environment
- it takes comparatively less time to complete
autogenic succession
driven by the effect of the plants on their habitat
- biotic factors
- secondary succession starts with autogenic succession
allogenic succession
driven by major environmental change: changing external geophysical processes
- abiotic factors –> outside influence, not within the existing community itself
- primary succession starts with allogenic succession and proceeds to autogenic succession
progressive succession
increase community complexity, results in mesic habitats (a type of habitat with a well balanced or moderate supply of moisture throughout the growing season)
- example would be secondary succession
retrogressive succession
decreases community complexity, results in more extreme habitats
- example would be ecosystem retrogression
directional succession
cyclic succession
successional changes on a very local scale
transition matrices
-use column vectors to represent current stage
- use transition matrix for transition probabilities
- matrix multiplication predicts future population
CAUTIONARY NOTES
- Markoff Modelling– are such assumptions valid?
- if model too simple– ignores important life history differences
- best models reasonably complex and involve studies over time
chronosequence
a mosaic that reflects different stages of success following disturbance or successive exposure of new land
- describes a set of ecological sites that share similar attributes but represent different ages –> common assumption is that no other variable besides age has changed between sites of interest
toposequence
a mosaic that reflects topographic (the arrangement of the natural and artificial physical features of an area) differences. each community in a toposequence may be a climax community
- shows different in soils and vegetation along a slope
methods of evaluating vegetation changes over long periods of time
(1) dendrochronology
(2) analysis of pack rat middens
(3) pollen profiles
dendrochronology
trees are sensitive to local climate conditions, such as rain and temperature and can give scientists some info about that area’s local climate in the past. for example, tree rings usually grow wider in war, wet years and they are thinner in years when it is cold and dry
pack rat middens
collections of debris, such as plants, rocks, bones, and other artifacts that preserve key environmental information from as far back as 45,000 years ago –> lmaooooo mice pee on them the urine acts as a preservative hahahaha
ex so i can understand better, basically they found some midden somewhere and found juniper twigs but there were no junipers in the area. could date the juniper twigs and found that that many years ago, the climate was suitable for junipers but had changed
pollen profiles
by analyzing pollen from well-dated sediment cores, paloeclimatologists can obtain records of changes in vegetation going back hundreds of thousands, and even millions of years
- changes in vegetation can show us climate change as we can see what plants were well suited to that environment and when
southern californian vegetation
- cismontane (chaparral)
- transmontane (deserts)
-montane (forests) - other (vernal pools, islands)
southern californian threats to vegetation
invasive species
california climate and weather (come back to first slide deck of california)
- winter cold, summer heat
- fog, little rain
(a) west coast
(b) latitude
(c) mountains – rainshadows
serpentine soils
CHARACTERISTICS
- derived from metamorphic or igneous rocks exposed during Tertiary
- high in magnesium, silicates, and heavy metals
- low in essential elements, e.g. N, Ca, K, and P
- little profile development
VEGETATION
- differs in physiognomy and species composition
CATEGORIES OF TAXONOMIC AND EVOLUTIONARY RESPONSES
- taxa endemic to serpentine
-local or regional indicators
- indifferent taxa
- serpentine avoiders
cismontane southern California
southwestern portion of CA, “this side of the mountains”
- dominant vegetation is chaparral; sclerophyllous, evergreen shrubs with small leaves
cismontane socal – climate
typical mediterranean: cool wet winters, hot dry summers
cismontane socal – other factors influencing vegetation
- slope and aspect
- coastal versus desert exposure
-elevation - substrate
- fire
cismontane socal – plant communities
- salt marshes
- coastal dune
- coastal scrub
- chaparral communities
- oak woodland communities
- valley grassland communities
- riparian woodlands and vernal pools
cismontane socal – toposequence
increasing elevation –>
COASTAL
salt marshes/dunes –> coastal shrub –> chaparral
INLAND
valley grasslands –> oak woodlands –> riparian woodlands and valleys
coastal wetlands
associated with estuaries, bays, inlets and shores protected from wave action
- have a mix of fresh and saline water
- distribution along the cali coast is: discontinuous, small in area, reflects low rainfall and a steep coastline
- ecologically very important
coastal wetlands – physical environment
physical environment is dominated by TIDAL ACTION that affects soil
- temperature
- O2 and CO2
-salinity
- water
- nutrients
frequency and duration of tidal flushing change with lunar cycle and elevation, resulting in gradients in the above environmental factors
estuaries and sedimentation
estuaries are also sites of sedimentation. differences in currents within the estuary result in zones of different textures soils within the wetlands –> high tide and low tides
vegetation of coastal wetlands
low species diversity (extreme environment)
ESTUARINE COMMUNITIES
- occurs in the channels
- very flexible plant body (e.g. eel grass)
SALT MARSH
- intertidal
- vegetation of socal is more closely similar to arid mediterranean floras of baja california than those of wetter canadian sites
- larger number of succulent and rhizomatous species
- plants are typically low-growing perennial halophytes with reduced leaves and succulent - flowers are highly reduced and wind pollination is common
vegetation usually shows ZONATION ; structure or arrangement in zones
adaptations in coastal wetlands
-rhizomes (anoxia)
- aerenchyma (anoxia)
- oxidation of rhizosphere (anoxia induced nutrient stress/toxicity)
- accumulation of solutes (water stress)
- succulence (salt dilution)
- foliar salt grands (salt excretion)
adaptations in coastal wetlands – anoxia
anoxia = an absence of oxygen, caused by too much water/ flooding, eliminates and replaces oxygen in the soil
- rhizomes; near surface, more chance of getting O2, stores starch to provide carbon which aids with the stress
- aerenchyma; open channels for oxygen in roots, also helps with ethanol leaving the plant
adaptations in coastal wetlands – accumulation of solutes
- water stress
- maintains transpiration
get more on this if can
adaptations in coastal wetlands – salinity
- salt exclusion at the root level
- succulence
- semi-deciduous habit
- salt excretion through glands
SUCCULENCE - dilution
- semi-deciduousness
SALT EXCRETION
-quantitatively reduces salt stress - reduces imbalance of some ions
dune (and beach) communities
these are the first terrestrial plant communities above the high tide line where sandy substrate occurs
- distribution is discontinuous, less than 23% of the CA coastline
- steep coastline
-dunes geologically young
-many older dunes washed away when sea levels rose post-glaciation
-impacted by coastal development
TOPOSEQUENCE
increasingly inland –>
pioneer dune communities (beach) –> dune scrub communities –> chaparral communities
dune (and beach) communities – physical environment
- mild climate (maritime – little temp fluctuation) but harsh environment
- high exposure to onshore wind, salt spray, sand blasting, shifting sand substrate
- very different vegetation occurs along the toposequence
- sandy soil with low water holding capacity, low fertility, low humus, soil salinity up to 1%
- little vegetation: rapid change/extreme temperatures in the soil, high reflection and heat loading in the plants
vegetation of beaches and dunes
low species diversity and low cover —> diversity and cover increase as one progresses inland
TYPICAL PIONEER DUNE SPECIES
- herbaceous
- evergreen
- perennials
- leaves entire for wind resistance
- prostrate (withstand burial)
DUNE SCRUB SPECIES
- larger shrubbier species (reduced by wind-pruning)
adaptations of beaches and dunes
- may be halophytic (salt tolerant plants)
- xerophytic (adaptations to survive in an environment with little liquid water) although internal dew formation
- hairs to reflect light
- thick cuticles for sand blasting
coastal sage scrub physical environment
-maritime climate
- precipitation low
- fog important
coastal sage scrub physiognomy
-soft stemmed shrubs
- suffrectescent (having a woody base that does not die down each year)
- drought deciduous or evergreen (a few winter deciduous)
north-south differentiation is observable in communities –> latitude (south softer and lower growing) and aspect
some species are intermediate between coastal scrub and true chaparral
coastal sage scrub and fire
coastal sage is feral to chaparral in fire succession (A seral community is an intermediate stage found in ecological succession in an ecosystem advancing towards its climax community)
- fire in coastal sage: regenerate by reseeding and resprouting
chaparral
thicket of scrubby evergreen oaks
- does not have to include oaks but is sclerophyllous
- geographic distribution follows mountains; reflects occurrence on rocky slopes from 2000 to 4000 ft
chaparral – physical factors
mediterranean climate interacting with substrate to limit water availability
-elevation affecting temperature, quantity, and type of precipitation
- aspect (the compass direction that a terrain surface faces)
species composition depends on elevation + aspect
- species may be codominant in these communities
- sometimes a single species dominates
warmer/lower chaparral
-700 to 1300 m
- below snow line, but frost
- poor soils
cold/upper chaparral
- above 1300 m
- above the snowline
- deeper organic acidic soils
- fog important
chaparral – physiognomy
woody shrubs (phanerophytes)
- leaves sclerophyllous: broad to needle with increasing drought
- leaves vertically oriented/sun tracking
- plants deep rooted
chaparral – adaptations
- to drought (leaf shape, root depth, volatiles, sclerophyll, evergreen)
- to low nutrients (sclerophyll, mycorrhizae)
- to temperature extremes (snow tolerance, sun tracking)
chaparral – adaptations to fire
seeds produced at early age, resistant to fire, maintained on plant, germination triggered by fire
- increased potential to adapt to change
- fire followers (pyroendemics)
- resprouting: from lignotudes
- spouting not dependent on summer rain
-plants retain established position
- growth more rapid than seedlings
chaparral – effects of fire on community structure
- maintains ‘vigor’
- evidence that plants evolved with fire
- plant characteristics ‘encourage’ fire (high flammability)
- post fire many annuals (pyro endemics) at low elevations
- fire frequency changes species composition
oak woodlands
- covers approximately 10% of california
- occur in the foothills of southern CA mountains
- transitional between grasslands and montane vegetation
- more mesic conditions have higher density of trees
- deep root systems, little summer dormancy
- thick bark protects from fire
- fog drip and shade required for seed germination
transmontane california – deserts
- deserts which cover a greater area in southern California
-three california deserts (all rain shadows)
(1) Great Basin (Cold desert); winter precipitation, spring growth
(2) Mojave Desert (High desert); winter precipitation, winter and spring growth
(3) Sonoran Desert (Low desert); winter and summer precipitation, winter and summer growth
deserts – physical factors
areas that have less than 250 mm precipitation per annum
1. low unevenly distributed precipitation
2. temperature extremes
3. windy (increased evaporation rates)
4. high light intensity
5. nutrient-poor, alkaline soil
6. low rates of primary production
deserts – growth forms
deserts have many different growth forms. this reflects niche separation in response to temporal and spatial variation in water supply
- some trends: increasing diversity and size of succulents in warmer deserts, increasing proportion of therophytes with decreasing/variable rainfall
common growth forms in socal
- perennials
- phreatophytes
- halophytes
- drought tolerant evergreens
- drought deciduous plants
- succulents
- annuals
- drought-avoiding ephemerals
-phreatophytes
look through California 5
did you do it? ok cool :)
montane – montane meadows
- shallow continuously moist soil in upper montane areas
- treeless
- distinct array of perennial herbs: grasses, sedges, rushes, broad-leaved herbs
- can be successional from montane lake to coniferous forest
montane – alpine fell field
- above the timber line
- rock strewn alpine desert
- cushion like mats of plants
- phloxes, buckwheat
vernal pools
- shallow ephemeral bodies in grasslands and woodlands
- underlain by calcerous hardpan, bedrock, or claypan
- wet in winter and drying during summer drought
- may become saline or alkaline during evaporation of water
- species composition reflects: aquatic environment, salinity, island nature of vernal pools
- species predominantly herbaceous aquatic or semi-aquatics, mostly annuals and some perennials
- many vernal pool endemics, many endangered species
grasslands
warm valleys - inland + coastal marine terraces
- precipitation low and irregular (25 - 50 cm)
- warm (>30 C in summer)
- summer drought
- soil deep and fertile
- community a mixture of grasses and forbs
grasslands – growth forms
- many alien species in grasslands
- introduced grasses often dominate
- introduced forbs
grasslands – alien species
- introduction of domesticated animals by spanish resulted in overgrazing
- alien species brought in packaging, ballast, hay and livestock
- many alien species pre-adapted to a mediterranean environment and more tolerant of grazing
grasslands – disturbance
- undisturbed grasslands are rare, remain on serpentines
- many grasslands used for crop production
- fire has modified grasslands in the 12,000 years, increased the extent of grasslands and distribution of fire tolerant species
