Transcript Live across secession environments

Life across secession
environments
Succession
• Ecological succession" is the observed process of change in the
species structure of an ecological community over time. Within any
community some species may become less abundant over some time
interval, or they may even vanish from the ecosystem altogether.
Similarly, over some time interval, other species within the
community may become more abundant, or new species may even
invade into the community from adjacent ecosystems. This observed
change over time in what is living in a particular ecosystem is
"ecological succession".
• Every species has a set of environmental conditions under which it
will grow and reproduce most optimally. In a given ecosystem, and
under that ecosystem's set of environmental conditions, those
species that can grow the most efficiently and produce the most
viable offspring will become the most abundant organisms. As long as
the ecosystem's set of environmental conditions remains constant,
those species optimally adapted to those conditions will flourish.
• Ecological succession may occur when the conditions of an
environment suddenly and drastically change. A forest fires, wind
storms, and human activities like agriculture all greatly alter the
conditions of an environment. These massive forces may also destroy
species and thus alter the dynamics of the ecological community
triggering a scramble for dominance among the species still present.
Stages of succession
Primary succession
Secondary Succession
Climax community
• Pond A: Cattails, bulrishes, and water lilies grow in the pond. These plants have their
roots in the bottom of the pond, but they can reach above the surface of the water. This
pond is an ideal habitat for the animals that must climb to the surface for oxygen.
Aquatic insect larvae are abundant. They serve as food for larger insects, which in turn
are food for crafish, frogs, salamanders, and turtles.
• Pond B: Plankton growth is rich enough to support animals that entered when the pond
was connected to the lake. Fish make nests on the sandy bottom. Mussels crawl over the
bottom.
• Pond C: Decayed bodies of plants and animals form a layer of humus over the bottom of
the pond. Chara, a branching green algae, covers the humus. Fish that build nests on the
bare bottom have been replacedby those that lay their eggs on the Chara.
• Pond D: The pond is so filled with vegetation that there are no longer any large areas of
open water. Instead, the pond is filled with grasses. The water dries up during the
summer months
• http://www.biologycorner.com/worksheets/examining_stages_succession.html
• The climax community in the area of Michigan is a beech-maple
forest. After the ponds are filled in, the area will undergo another
series of stages of succession. This is illustrated below. Briefly explain
what is happening in the diagram below.
• Primary Succession
• Primary succession begins when organisms move into a landscape
previously devoid of all living things following a major disaster, such as the
eruption of a volcano that completely destroys the prior environment. This
succession involves a total rebuilding of the ecosystem. For example,
primary succession requires the regeneration of nutritive soil, which can
take centuries and which means the first generation of new plants will
mostly be small shrubs and grasses.
•
Pioneer Plants
• Dune building
• Pioneer plants
• Grasses with long roots
• Grey dunes The dunes by now have a more or less continuous plant
cover, effectively anchoring the dune sand in one place. Where a
series of dunes has formed at the back of the beach, this stage will be
on the dunes further inland.
• Dune shrubs The build-up of humus from all the decaying vegetation
of previous stages, means that the sand has by now developed into a
poor sandy soil, capable of supporting pasture grasses and bushes.
• Bushes will develop on the tops and in the hollows of the dunes.
These will include species such as
• Trees climax ecosystem
• The final stage in dune stabilization is often achieved by planting
conifers, such as Corsican Pine, which is very tolerant of salt.
• Even in the absence of tree planting, the dunes will eventually
develop into woodland.
• Secondary Succession
• Secondary succession also involves the influx of organisms, but in this
case they are entering an environment damaged but not devoid of
life. This would include, for example, an ecosystem harmed by wild
fire or aggressive logging. In this scenario, plants return more rapidly
and more robustly. For example, in addition to grasses and shrubs,
hardwood trees would begin to grow much earlier. As a result, a full
secondary succession progresses much more quickly.
•
The Major Points:
• The species living in a particular place gradually change over time as does
the physical and chemical environment within that area.
• Succession takes place because through the processes of living, growing
and reproducing, organisms interact with and affect the environment
within an area, gradually changing it.
• Each species is adapted to thrive and compete best against other species
under a very specific set of environmental conditions. If these conditions
change, then the existing species will be outcompeted by a different set of
species which are better adapted to the new conditions.
• The most often quoted examples of succession deal with plant succession.
It is worth remembering that as plant communities change, so will the
associated micro-organism, fungus and animal species. Succession involves
the whole community, not just the plants.
• Change in the plant species present in an area is one of the driving
forces behind changes in animal species. This is because each plant
species will have associated animal species which feed on it. The
presence of these herbivore species will then dictate which particular
carnivores are present.
• The structure or 'architecture' of the plant communities will also
influence the animal species which can live in the microhabitats
provided by the plants.
• Succession is directional. Different stages in a particular habitat
succession can usually be accurately predicted.
• These stages, characterised by the presence of different communities,
are known as 'seres'
• Communities change gradually from one sere to another. The seres
are not totally distinct from each other and one will tend to merge
gradually into another, finally ending up with a 'climax' community.
• Succession will not go any further than the climax community. This is
the final stage.
This does not however, imply that there will be no further
change. When large organisms in the climax community, such as
trees, die and fall down, then new openings are created in which
secondary succession will occur.
• Many thousands of different species might be involved in the
community changes taking place over the course of a succession. For
example, in the succession from freshwater to climax woodland.
• The actual species involved in a succession in a particular area are
controlled by such factors as the geology and history of the area, the
climate, microclimate, weather, soil type and other environmental
factors.
For example, the species involved in a succession from open
freshwater to climax woodland in Central Africa, would be quite
different to those which have been quoted in these pages as
occurring in Britain. However, the processes involved would be the
same.
• Succession occurs on many different timescales, ranging from a few
days to hundreds of years.
It may take hundreds of years for a climax woodland to develop, while
the succession of invertebrates and fungi within a single cow pat (cow
dung), may be over within as little as 3 months.
By this time, the dung has been transformed into humus and
nutrients and has been recycled back into the soil. The holes clearly
visible in the cow pat (right) have been made by the animals which
have colonized it.
• http://www.countrysideinfo.co.uk/successn/summary.htm
Climax communities
• Characteristics
• The vegetation is tolerant of environmental conditions.
• It has a wide diversity of species, a well-drained spatial structure, and
complex food chains.
• The climax ecosystem is balanced. There is equilibrium between gross
primary production and total respiration, between energy used from
sunlight and energy released by decomposition, between uptake of
nutrients from the soil and the return of nutrient by litter fall to the soil.
• Individuals in the climax stage are replaced by others of the same kind.
Thus the species composition maintains equilibrium.
• It is an index of the climate of the area. The life or growth forms indicate
the climatic type.
• https://www.marietta.edu/~biol/biomes/succession.htm
• http://www.tarleton.edu/Departments/range/Woodlands%20and%2
0Forest/Pacific%20Northwest%20Forests/PacificNorthwestForests.ht
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• Animal life also exhibit changes with changing communities. In lichen
stage the fauna is sparse. It comprises few mites, ants and spiders
living in the cracks and crevices. The fauna undergoes a qualitative
increase during herb grass stage. The animals found during this stage
include nematodes, insects larvae, ants, spiders, mites, etc. The
animal population increases and diversifies with the development of
forest climax community. The fauna consists of invertebrates like
slugs, snails, worms, millipedes, centipedes, ants, bugs; and
vertebrates such as squirrels, foxes, mice, moles, snakes, various
birds, salamanders and frogs.
What Animals Live in the Redwood Forest?
• There are numerous large animals that live in the redwood forest,
some of which hikers must watch for as they can be dangerous. There
are mountain lions, bobcats, black-tailed deer, elk, black bear and
coyotes to name a few. Bobcats may be seen in the forest or open
areas, and are active day and night. They have a bobbed tail, pointy
ears with tufts and are gray to reddish in color. Mountain lions are a
larger cat than bobcats and are tan in color with a long tail. Black bear
are also active in the forest and open areas. If you see a black bear do
not run, but stop and slowly back away while making noise. Most of
these animals have no intention of hunting down humans, but can
react harmfully if frightened or when threatened
• Midsize animals are not as much of a worry to your safety as they are
to your belongings. Leave your lunch out or your pack unattended
and you may find that an animal--a raccoon for example--has claimed
some of your goods as his own. There are gray foxes--one of the only
canines that can climb trees--Coho Salmon, northern spotted owls,
turkey vultures, river otters and beavers in the redwood forest. Some
are specific to water, such as salmon otters and beavers, while others
can be seen roaming all sorts of areas. Owls of course are mostly
nocturnal but if you keep a watch during dusk you may be lucky
enough to spot one. The northern spotted owl is an endangered
species
• A few of the many small animals that live in the redwood forest are
the pacific giant salamander (which feed on banana slugs and are not
much bigger than a quarter), Sonoma chipmunks, dusky-footed
woodrat, western gray squirrels, Steller's jays and banana slugs, which
are bright banana yellow. Water striders, also called water skaters, are
just one of hundreds of insects inhabiting the forest and can be seen
gliding atop water. Water striders eat other smaller insects and are
themselves food for many others, such as the pacific giant
salamanders. Many of the smaller animals feed on things such as
nuts, seeds, fruit, buds and mushrooms as they are near the bottom
of the food chain.
• https://www.trails.com/list_3254_what-animals-live-redwoodforest.html