Exam 1 Flashcards
Ecology
The study of the reciprocal relationship between organisms and the environment.
Ecosystem
The sum of interactions of plants, animals, and the environment.
Carl Ludwig Willdenouw
Pioneer plant geographer who noted that similar climates produce similar vegetation (physiognomy).
Physiognomy
The physical characteristics of vegetation, such as life form and canopy characteristics
F.H.A. von Humboldt
Student of Willdenouw. Last of the renaissance men.
Correlated vegetation to climate.
“In the great chain of causes and effects, no one factor should be viewed in isolation.”
Clinton H. Merriam
Developed concept of Life Zones (vegetation is correlated to sum degrees of warmth, especially growing season warmth)
Silviculture
The science and art of controlling forest establishment and growth.
What are all of the biomes on Earth?
- Desert
- Arctic and Alpine Tundra
- Grasslands
- Woodlands
- Boreal
- Temperate broad-leaved deciduous
- Temperate broad-leaved evergreen
- Temperate needle-leaved deciduous
- Temperate needle-leaved evergreen
- Tropical broad-leaved deciduous
- Tropical broad-leaved evergreen
What factors influence the classification of biomes?
Environmental factors (ex: temperature and moisture) and physiognomy (physical characteristics of the vegetation)
Desert
High temperatures
Extremely low precipitation
Dominated by C4 and CAM plants
Tundra (Arctic and Alpine)
AKA Cold deserts.
Shortest growing season (
Permafrost in arctic tundra soil
Strong soil freeze-thaw process
ALPINE in high elevation
ARCTIC in high latitude
Grasslands
Very fertile ► agriculture/heavy human impact
black soil = RICH + FERTILE due to lots of root turnover
height/stature of grassland dictated by precipitation
Woodlands
Inconsistent definitions, mostly a transition from GRASSLANDS to FOREST
Can be deciduous or evergreen
Very fire prone
Boreal Forests
Latitude > 50
30-120 days > 10 C
SECOND LARGEST forest biome in the world
ground cover dominated by bryophytes
low canopy diversity
open canopy with individual conical crown
wildfire dominated
Temeperate Broadleaf Deciduous Forests
Mostly in N hemisphere
Nitrogen limited
very diverse
Ex: Riparian forests in S USA (pneumatophores in anaerobic soils)
Temperate Broadleaf Evergreen Forests
Two major subgroups: Schlerophylls (Mediterranean, Asia)
Rainforests (NZ, Chile, Australia)
Heavily logged
Temperate Needle-Leaf Evergreen Forests
Ex: CA Redwood
Very conical trees
Management issues: Logging, Fire, and Drainage
Tropical Broad-Leaf Deciduous Forests
Drier, has undergone greatest deforestation
Lower biodiversity than Tropical Broadleaf Evergreen
Deciduous to avoid drought (Ann. Prec. < 1500 mm)
Has complex symbioses
Tropical Broadleaf Evergreen Forests
LARGEST forest biome of the world
HIGH Biodiversity
Multi-storied
Undergoing greatest land use change
INFERTILE soils
Ann Prec. > 1500 mm
Deforestation from: Grazing, shifting agriculture, and charcoal
Primary Tree Growth
Vertical
Roots and Shoots
Secondary Tree Growth
Lateral Growth
Excurrent Tree Form
Terminal shoot exerts apical dominance over lateral shoots.
Leads to conical shaped trees
Decurrent Tree Form
Terminal shoot does NOT exert apical dominance
Leads to top-heavy/bushy trees
How does tree form indicate adaptations to an environment?
Excurrent is best at shedding snow/ice and absorbing low-angle/diffuse light
Decurrent absorbs more direct sunlight and hence is more adapted to relevant environments
Explain the structure of a tree stem: Cambium, Xylem (Sapwood and heartwood), Phloem, and Bark
What is the difference between sapwood and heartwood?
Sapwood: Alive, outer, conducts food and water
Heartwood: Dead, structural support
Explain the Pipe Theory Model
Higher leaf area is correlated with higher amts of sapwood.
Tracheids vs. Vessels
Tracheids slower at conduction, but vessels more susceptible to cavitation and damage
When do plants usually begin secondary growth?
After fine root production
What types of trees can we use ring-aging for?
Temperate trees.
Can NOT use it for tropical trees, esp when false rings are made due to wet and dry seasons
What are the differences between SUN leaves and SHADE leaves?
Sun leaves are smaller for less dessication at top of tree where they get more light.
Shade leaves are larger to get more sunlight, less deeply lobed, and thinner with less stomata
Coarse Roots
Function: TREE ANCHORING and some nutrient storage
Fine roots
2-5 mm and smaller
Function: WATER AND NUTRIENT ABSORPTION
most occur in the upper 30 cm of soil
Pneumatophores
Root projections above ground thought to aid in O2 exchange
Buttress Roots
Aboveground exposed roots that allow trees to adapt to high water levels.
What are the two types of mycorrhizae and how do they differ?
ENDOmycorrhizae (most common): hyphae penetrate cortical cells (Ex: Maple, Poplar)
ECTOmycorrhizae: less common, but many important timber species. Form a mantle around the roots. (Ex: Pine, Oak)
BOTH help plants uptake water/nutrients
What factors control Myborrhizae development?
Negatively related to nutrient and water availability
Positively related to photosynthate production
How much of the sun’s incident radiation is UV?
~10%
Affected by Ozone abundance
What wavelengths do plants use for photosynthesis?
PAR = 400-700 nm
Visible only
What is one way pilots can measure deforestation?
Measuring the RED : INFRARED ratio. More red = less plants, since plants absorb red, but not far-red.
What is LAI?
Leaf Area Index
AKA the proportion of leaf area per unit area of land
What are the components of the energy budget?
S=R+C+G+LE+Ps
S= Solar radiation
R= Reflected solar radiation
C= Convection
G= conduction
LE= latent heat of vaporization
Ps=photosynthesis
Albedo
Reflectivity of a material summed over all its wavelengths
Bowen Ratio
Convection (C): (LE) Latent heat of vap.
Ecologists use it to characterize enviro conditions
Beer-Lambert Law
Iz/Io = e^(-k * LAI)
or
ln(Iz/Io)=-(k)(LAI)
How does the sunlight efficiency of plants compare to that of solar panels?
Plants only convert about 1% of incident sunlight into biomass, whereas solar panals convert about 20% or as much as 40% in some cases.
Light Compensation Point
Amount of PAR where photosynthesis exactly counters respiration.
Net carbon balance = 0
Light Saturation Point
Amount of PAR above which Ps will not increase any more
How do plants sense day length?
Phytochrome far-red (Pfar-red) is activated from Pred upon incident red light. Pfar-red is the bio-active form.
Homeotherms vs. Poikilotherms
HOMEO: maintains constant body temperature independent of the environment
POIKILO: doesn’t regulate body temp, depends on environment
What factors influence variations in temperature?
Changes in Earth’s tilt and orbit
Latitude
Elevation - 4° for every 1000 m in elevation
Aspect
Proximity to water
Albedo
Raunkiaer Life History Classification Scheme
Classifies life history of plants based on location of bud(s) to protect them from extreme temperatures.
Phanerophytes
Buds higher than 25 cm
Chaemophytes
Buds lower than 25 cm
Hemi-Cryptophytes
Buds at soil surface
Geophytes
Buds below the soil surface
Therophytes
Complete their entire life cycle within the year
How do cold temperatures affect plant growth and how have plants adapted?
COLD: decreased root membrane permeability
Frost cracks and heaving
Dessication
ADAPTATIONS: dormancy
thick bark
germ bud below ground
remove free water from bud
How do hot temperatures affect plant growth and how have plants responded?
HOT: protein degradation
dehydration
excessive respiration
ADAPTATIONS: Deciduous leaf habit
Thick bark
small foliage
reflective leaf structures
leaf orientation
Components of the Hydrologic Cycle
W = P-(R+S+E+T)
W=Δ water storage
P= Precipitation
R= Runoff
S= Subsurface drainage
E= evaporation
T= transpiration
Orographic Precipitation
Pattern of Precipitation - Rain shadow effect on mountains
Windward side gets more precip than leeward
Frontal Precipitation
Warm fronts - low intensity
Cold fronts - high intensity
Convective Storms
THIRD pattern of precipitation
heating of air mass at earth’s surface.
Intense but brief
Can be part of a frontal system
Hydrophytes
Plants that are tolerant of large amounts of water
Mesophytes
Plants that tolerate moderate water
Xerophytes
Plants that tolerate extremely low soil moisture
What are the soil horizons and what do they consist of?
O = organic matter
A horizon = mineral soil, zone of ELuviation
E or AB = transition zone
B Horizon = zone of ILLuviation
Where does Mor Soil occur?
Coniferous forests
Where does Mull soil occur?
Hardwood forests
Gelisols
Tundra soils with PERMAFROST
Slow decomposition
Histisols
Organic soils -> Mucky and peat soils
Spodosols
Acids from vegetation mix with metal oxides
CONIFEROUS FORESTS
Andisols
High water-holding capacity
Fixes P -> not avail to plants
Entisols
RECENT origin -> sandy with little color
Inceptisols
Older than entisols, but still lacks features.
Occurs in Mountains
Alfisols
MOST FERTILE
lower base saturation than MOLLISOLS
Ultisols
Non-glaciated, hotter, wetter areas
ACIDIC and LEACHED
Oxisols
MOST WEATHERED
tropical areas ONLY
LEAST fertile
Vertisols
Clay-rich, swells a lot
Aridisols
Dry most of the year
Mollisols
Prairies and Grasslands
What are the three components of water availability?
- Field Capacity: gravitational water in MACROpores
- Available water: capillary water in MICROpores
- Permanent WIlting Point: Hygroscopic water that is unavailable and stuck to soil particles
What are natrual sources of soil acidity?
Organic Acids
Bicarbonate from root respiration and decomp
Nitrate from nitrification by chemoautotrophs
How does pH affect plant growth?
Alters nutrient availability
Affects root membrane permeability
Decreases microbial diversity
CEC
Cation Exchange Capacity: capacity of a soil to hold cations to the negative particle surface
CEC = equivalents per gram
Factors that influence CEC
% organic matter
soil texture
clay type
pH
Isomorphic substitution
the substitution of Al3+ for Si4+ in soil interlayers.
Governed by SIZE, not charge
Base saturation
percentage of CEC that is occupied by exchangeable bases (Ca2+, Mg2+, K+, Na+) relative to ALL bases (add H+ and Al3+)
correlated with higher pH and soil fertility
