Chapter 11: Terrestrial Flora and Fauna – p. 8 of 13
Chapter 11: Terrestrial Flora and Fauna
I. Ecosystems and Biomes
A. Ecosystem: A Concept for All Scales
1. ecosystem: an association of plants and animals along with the surrounding nonliving environment and all the interactions in which the organisms take part
2. ecosystem concept is built around the flow of energy
3. can be applied at various scales: global ecosystems; ecosystem of the underside of a rock; etc.
B. Biome: A Scale for All Biogeographers
1. biome: any large, recognizable assemblage of plants and animals in functional interaction with its environment
2. most appropriate scale for understanding world distribution patterns
3. biomes are usually identified and named on the basis of its dominant vegetation which normally makes up bulk of the biomass
4. 10 major terrestrial biomes:
a. tropical rainforest
b. tropical deciduous forest
c. tropical scrub
d. tropical savanna
e. desert
f. Mediterranean woodland and scrub
g. Midlatitude grassland
h. Midlatitude deciduous forest
i. boreal forest
j. tundra (Arctic and alpine)
5. biome includes other vegetation as well as diverse animal species
6. significant and predictable relationships exist between the biota of a biome and the associated climate and soil types
7. ecotone: the transition zone between biotic communities in which the typical species of one community intermingle or interdigitate with those of another
II. Terrestrial Flora
A. reasons geographers are interested in the natural vegetation:
1. over much of the planet, terrestrial flora is the most significant visual component of the landscape
2. vegetation is sensitive indicator of other environmental attributes
3. vegetation influences human settlement and activities
B. Characteristics of Plants
1. perennials: plants that endure seasonal climatic fluctuations from year to year
2. annuals: plants that perish during times of climatic stress (such as winter) but leave behind a reservoir of seeds to germinate during the next favorable period
C. Floristic Terminology
1. plants that reproduce through spores:
a. Bryophytes
1) true mosses, peat mosses and liverworts
2) have never been very important
b. Pteridophytes
1) ferns, horsetails, club mosses
2) more important in past
2. plants that reproduce through seeds
a. gymnosperms/conifers (naked seeds)
1) carry their seeds in cones
2) more important in past
3) only large survivors are cone-bearing trees such as pines
b. angiosperms (vessel seeds)
1) flowering plants
2) seed encased in some sort of protective body: fruit, nut or pod
3) have dominated vegetation for last 50-60 million years
3. stem or trunk composition
a. woody plants: stems composed of hard fibrous material
b. herbaceous plants: soft stems
4. leaf loss
a. evergreen tree: sheds its leaves on a sporadic or successive basis but always appears to be fully leaved
b. deciduous tree: experiences an annual period in which all leaves die and usually fall from the tree, due either to a cold season or a dry season
5. leaf shape
a. broadleaf trees:
1) leaves are flat and expansive in shape
2) almost all broadleaf trees are deciduous except in rainy tropics where everything is evergreen
b. needleleaf trees:
1) leaves are tough, leathery waxy needles
2) almost all needleleaf trees are evergreen
6. wood
a. hardwood: angiosperm trees that are usually broad leaved and deciduous; wood has a relatively complicated cellular structure
b. softwood: gymnosperm trees; nearly all needleleaf evergreens; wood has a simple cellular structure
D. Environmental Adaptations
1. intro
a. definite tolerance limits govern plant survival, distribution, and dispersal
b. plants have evolved protective mechanisms to enlarge their tolerance limits
2. Xerophytic Adaptations
a. xerophytes: plants that are structurally adapted to withstand protracted dry conditions
b. xerophytic adaptations:
1) roots are modified into shapes or sizes to enable them to seek widely for moisture
2) stems are modified into fleshy, spongy structures that can store moisture
a) plants with such fleshy stems are called succulents; ex. cacti
3) leaves are modified to decrease transpiration
a) surface is hard or waxy to inhibit water loss
b) surface is white and shiny to reflect insolation and reduce evaporation
c) plants have tiny leaves or no leaves at all
d) leaves are replaced by thorns from which there is virtually no transpiration
4) reproductive adaptation: plants lie dormant for years waiting for moisture then complete entire reproductive cycle in a few days
3. Hygrophytic Adaptations
a. hydrophytes: plants living more or less permanently immersed in water (water lily)
b. hygrophytes: moisture-loving plants that require frequent soakings with water (ferns, moss, rushes)
c. hygrophytic adaptations:
1) extensive root systems for anchoring to soft ground
2) widening, flaring trunk near ground to provide better support
3) weak, pliable stems that can stand the current’s ebb and flow
E. Competition and the Inevitability of Change
1. plants are as competitive as animals
2. compete for nutrients from same soil and energy from same sun
3. the floristic pattern of Earth is impermanent
a. general sequential trend is toward taller plants and greater stability in species composition
b. the longer plant succession continues, the more slowly change takes place because more advanced associations contain species that live longer
c. climax vegetation: a stable plant succession of relatively constant composition that develops at the end of a long, succession of changes
1) seral associations: stages leading up to climax vegetation
2) represent optimal floristic covering for that environmental context
3) an association in equilibrium with prevailing environmental conditions
F. Spatial Associations of Plants
1. identifying and mapping associations
a. boundaries on maps represent approximations
b. most world vegetation maps are maps of theoretical natural vegetation
1) ignore human interference
2) over extensive areas of Earth’s surface climax vegetation is the exception rather than the rule
2. The Major Floristic Associations
a. Forests
1) trees growing so closely their individual leaf canopies overlap
2) shade precludes development of much undergrowth
3) require considerable annual precipitation
4) survive in widely varying temperature zones
5) except where inadequate moisture or short growing season, forest are likely to become climax vegetation association in any area
b. Woodlands
1) tree-dominated plant association
2) trees spaced more widely apart
3) ground cover not inhibited by lack of sunlight
4) environment drier than forests
c. Shrublands
1) dominated by short woody plants: shrubs or bushes
2) wide latitudinal range
3) generally restricted to semiarid or arid locales
d. Grasslands
1) may contain scattered trees and shrubs, but dominated by grasses and forbs (broadleaf herbaceous plants)
2) savanna: low-latitude grasslands characterized by tall grasses
3) prairie: mid-latitude grasslands characterized by tall grasses
4) steppe: midlatitude grasslands characterized by short grasses and bunchgrass
5) associated with semiarid and subhumid climates
e. Deserts
1) widely scattered plants with much bare ground interspersed
2) climatic term
3) wide variety of plants: grasses, succulent herbs, shrubs, scraggly trees
4) some extensive desert areas devoid of all vegetation
f. Tundra
1) complex mix of very low plants, but no trees
2) perennially cold climates of high latitudes or high altitudes
g. Wetlands
1) limited geographic extent
2) swamps: trees are dominant plant forms
3) marshes: grasses and other herbaceous plants dominate
3. Vertical Zonation
a. significant elevation changes in short horizontal distances ® various plant associations in relatively narrow zones on mountain slopes
b. result of effects of elevation on temperature and precipitation
c. elevation changes are the counterpart to latitudinal changes
1) sea level to top of tall tropical peak is roughly equivalent to horizontal journey from equator to Arctic
2) Fig 11-12 graphs northern hemisphere treeline (elevation at which trees are unable to survive due to low summer temperatures and moisture availability) variation with latitude: at 40oN latitude in Colorado treeline is 10,000 feet
3) all vegetation zones are displaced downward with increasing distance from the equator
4) accounts for vegetation complexity in mountainous areas
4. Local Variations
a. Exposure to Sunlight
1) adret slope: a slope oriented so that the sun’s rays arrive at a relatively direct angle that is more effective in evaporating available moisture
a) hot and dry
b) impact on vegetation
(1) sparser and smaller
(2) different species composition
2) ubac slope: a slope oriented so that the sun’s rays arrive at a relatively low angle
a) cooler ® less evaporation
b) more luxuriant vegetation of a richer diversity
3) differences between adret and ubac slopes decreases with increasing latitude
b. Valley-bottom location
1) variation reflects difference in perennial availability of subsurface moisture
2) riparian vegetation: anomalous stream-side growth, particularly prominent in relatively dry regions, where stream courses may be lined with trees, although no other trees are to be found in the landscape
III. Terrestrial Fauna
A. intro
1. animals occur in much greater variety than plants over Earth
2. less important as objects of geographical study:
a. animals much less prominent than plants in the landscape
b. environmental interrelationships are much less clearly evidenced by animals
3. animals are sometimes more sensitive indicators than plants of ecosystem health
B. Characteristics of Animals
1. animals are motile – capable of self-generated movement
2. animals cannot manufacture their own food
C. Kinds of Animals
1. Invertebrates
a. animals without backbones
b. more than 90% of all animal species
c. beetles are most numerous of animals: 40% of all insect species; more than ¼ of all known animals
2. Vertebrates: animals that have a backbone that protects the main nerve/spinal cord
a. fishes
b. amphibians
c. reptiles
d. birds
e. mammals
1) placental (great majority): young grow and develop in the mother’s body, nourished by the placenta
2) marsupial (135 species): mothers have pouches in which the very undeveloped young live for weeks or months after birth
3) monotremes (echidna and duckbill platypus): egg-laying mammals
D. Environmental Adaptations
1. Physiological Adaptations
a. majority of animal adaptation to environmental diversity has been anatomical and/or metabolic changes
b. examples: ear size, fur thickness, webbing, foot size, sweat glands
2. Behavioral Adaptations
a. advantage over plants: can move and therefore modify behavior to minimize stress
b. examples: shelter, travel, shift from diurnal to nocturnal, migration, hibernation, estivation (spending a dry-hot period in a torpid state)
3. Reproductive Adaptations
a. delay mating to postpone nest building
b. protracted egg, larval, or den stage
c. hastened estrus
E. People and the Environment: Changing Climate Affects Bird Population
1. bird populations can be especially sensitive to indicators of climate change
a. many species have specific requirements for feeding, nesting, and migration
b. because birds are quite mobile, they may respond fairly quickly to local environmental changes
c. in warmer years birds do not fly as far south for the winter as they do in cooler years and may spend their summers farther north
2. 2009 National Audubon Society Christmas Bird Count - 40 year study
a. 177 of 305 North American bird species are wintering an average of 35 miles farther north than 40 years ago
b. “center of abundance” for more than 60 bird species shifted 100 miles or more north
c. higher temperatures are most likely cause
3. other impacts
a. timing of bird migrations: several species are arriving in Michigan 2-3 weeks earlier in the spring
b. nesting time:
1) birds in some locations are nesting earlier because plants are blooming earlier which results in an earlier proliferation of insects
2) 20 of 65 species studied in Britain are laying eggs 9 days sooner today than they did 35 years ago
4. because habitats may respond to climate change in different ways, birds and other creatures may face a dislocated and altered habitat
F. Examples of Animal Adaptations to Desert Life
1. remain near a perpetual source of water (birds are more dependent on an open source of water than any other non-aquatic animal)
2. follow rain in nomadic fashion
3. spend a great deal of time underground
4. be nocturnal
5. kangaroo rats can exist from birth to death without ever taking a drink!! (surviving exclusively on moisture ingested with their food)
6. dromedary (one-humped camel)
a. anatomical adaptations
1) cleft lip designed to catch any moisture expelled from the nostrils
2) horizontal slits of nostrils can close tightly to keep out blowing sand
3) shaggy brows shade sun
4) double set of eyelids blocks blowing sand
b. physiological adaptations
1) body temperature range of 12oF reduces sweating
2) capable of rapid and complete rehydration in a short time period
7. delay reproductive processes during dry periods
G. Competition among Animals
1. between species: space and resources, plus direct antagonism of predation
2. within species: territory, mates, food
H. Cooperation among Animals
1. symbiosis: a mutually beneficial relationship between 2 dissimilar organisms
2. 3 forms:
a. Mutualism: mutually beneficial relationship between the 2 organisms, such as a tickbird and African ungulate
b. Commensalism: 2 dissimilar organisms living together with no injury to either, such as burrowing owls sharing prairie dog holes
c. Parasitism: one organism lives on or in another and obtains nourishment from the host, which is usually weakened or sometimes killed, such as mistletoe on forest trees
I. Zoogeographic Regions
1. distribution of animals over the world is more complex and irregular than plants because they are mobile
2. broad distribution of animals is reflective of the distribution of energy and food diversity:
a. richest faunal assemblages are in the permissive environment of the humid tropics
b. sparsest representations of both species and individuals are in the dry lands and cold lands
3. 9 zoogeographic regions:
a. Ethiopian Region: tropical or subtropical with rich and diverse fauna; primarily Sub-Saharan Africa
b. Oriental Region: similar faunal assemblage as Ethiopian Region but less diversity; southern Asia