Lecture 10 - Modern Ecosystems Flashcards
biomes
biomes def
grouping of terrestrial ecosystems that share similar vegetation structure, environmental characteristics, and animal communities
biomes
mediterranean (chaparral) biome
- hot dry summers
- mild wet winters
- mostly short, sclerophyllic vegetation (hard leaves)
- occurs in coastal areas on 5 continents
biome
temperature & precipitation
avg percipitation and temp set boundary conditions for what vegetation will be like
- at any given place, biome characteristics and local climate/resources play into vegetation
biomes
characteristics of vegetation growth
- temp. & percipitation
- herbivory
- fire
- soil quality (drained vs water logged)
- invasive/competition from other plants
ecological succession
what is ecological succession
change in structure of community after disturbance or initial colonization of new area
ecological succession
process of eco succession
- pioneer species - take advantage of new environment, establish quickly, takes weeks (ex: mosses, ferns)
- grasses - don’t invest large amount of energy (annuals)
- shrubs - woody, takes a bit longer
- trees - takes really long time
fast growing plants slowly overtaken by longer growing
ecological succession
primary succession vs secondary
new habitat vs after disturbance
- secondary only if everythingis destroyed
- many ecosystems are adapted for all but most intensive fires
ecological succession
climax vegetation
final, stable stage of plant communities
- trees capture all energy and block sunlight from reaching ground, prevents terrestrial vegetation from growing
vegetation strucutre
importance of vegetation structure
impacts the type and abundance of different resources - grass, leaves, fruits, animal prey
impacts how organisms of different body sizes can move through the habitat
bond (2008) discussion questions
bottom up factors of limiting tree growth
- soil & nutrients (certain areas where soil is unfavorable for growth of extensive woodland species)
- general abiotic factors (water etc)
bond (2008) discussion questions
top down factors limiting tree growth
- herbivory (grasses meant to be eaten, can regenerate unlike shrubs which take longer to grow)
- fire (^)
- human controlled fire (set so prey can be easily hunted, now used to maintain ecosystems supporting herds of favored animals)
bond (2008) discussion questions
competitive role of grass
grass roots shallower but denser than tree roots = turf formation, roots intertwined, barrier to establishing tree seedlings
bond (2008) discussion questions
current trends in grasslands, why, impacts
woody encrouchment - invasion of grassland areas
why? public pressure to supress human controlled fires allowing encroachment
bond (2008) discussion questions
what is a savanna
not forest, not grassland
dominated by c4 grasses, some c3 vegetation
bond (2008) discussion questions
why does phenomenon of extensive savannas in Africa need explanation
there is enough percipitation to support growth of extensive woody species, but instead extensive savanna
