Populations And Ecosystems (The structure of Ecosystem (trophic levels:…
Populations And Ecosystems
Plants in Relationship to Their Habitats
Abiotic components of habitat
: the survival of an organism on a certain region depends upon the the climatic conditions that the organism can resist.
: the nutrients that are present in the soil determines the plant's growth. the first plants that invade the new soil are called the pioneers.
layers of soil: after many years from the date of formation of a new soil, the soil divides into three layers:
B horizon: it is called the zone of deposition and consists of humus and clay. it is rich in nutrients.
C horizon: it is mostly composed of parent rock and rock fragments.
A Horizon: it is called zone of leaching and consists of litter and debris
latitude and altitude
at equator all days are 12 days long. therefore, no seasonal variation occurs.
at higher latitudes to either north or south, summer days be much longer, as do the winter nights. so variation can be seen on these regions.
Above arctic and antarctic circles, mid summers days are 24 hours long, so are the mid winter nights. so almost no plants can be see here.
disturbance: Disturbances are the phenomena such as fire,landslides, snow, avalanches and floods. they bring significant and radical change to the ecosystem.
biotic components of the habitat
The plant itself: the plant itself being in the habitat means the plant is modifying the habitat. Habitat modification might be beneficial,detrimental or neutral.
other plant species: when individuals of one species or other species come together then they react. the interaction can be mutualism or competition.
organism other than plants: animals, fungi and prokaryotes are important part of the plant's habitat. the various relation are commensalism, predation or pathogenic.
The structure of Population
Boundaries of the geographic range: the ability of a plant species to spread throughout a region depends on its adaptations with the biotic and abiotic factors of the enviroment. Limiting facors play a role in the growth and distribution of a plant.limiting factor resources are environmental conditions that limit the growth, abundance, or distribution of an organism or a population of organisms in an ecosystem.
local geographic distribution
ramdom distributuion: this term is used when there is no obvious, identifiable pattern to the position of the individuals.
clumped distribution: the distribution in which the spacing between plant is either small or large.
uniform distribution: distribution in which all the individuals are evenly spaced from their neighbors.
Age Distribution: Demography
analysis of age distribution in plants is hard to determine
generation time and intrinsic rate of natural increase affect population growth rate.
the manner in which population responds to various factors in its habitat is partly affected its age distribution
r- and k- selection
r-selected species are those that emphasize high growth rates, typically exploit less-crowded ecological niches, and produce many offspring, each of which has a relatively low probability of surviving to adulthood
a disturbance usually produces r selection
r selected species typically are annuals or small shrubby perennials.
they have few defense against predators
they reproduce quickly and population growth is extremely rapid
K-selected species, also called K-strategist, species whose populations fluctuate at or near the carrying capacity (K) of the environment in which they reside.
k selected species face intense competition from other plant species.
Douglas firs redwoods and bristle cone pines are good examples of k selected species
The structure of Ecosystem
physiognomic structure: the physical shape and size of the organisms and their distribution in relation to each other and to the physical environment constitute the physiognomic structure.
Temporal structure: the changes that an ecosystem undergoes with time constitutes its temporal structure; the time span can be short or very long.
Species composition: refers to the number and diversity of species that coexist in an ecosystem
trophic levels: feeding levels
producers L: plants that produce food
primary consumers: they feed on producers
secondary consumers: they feed on primary consumers
tertiary consumers: they feed on secondary consumers
decomposers: they decompose or breakdown the the remains of all types of organisms, even those of the other decomposers