Population Growth

Population Growth
 
A. Understanding Population
The population is an individual group of the same species and occupies in a small enough habitat to allow interbreding among members of all groups.
Some populations are not interlinked but do self-pollination or sexually reproduce. The occupied area allows the potential for gene exchange through self-pollination or neighbors.
Determination or classification of species in the population can be done in two ways:
1. Taxonomically, the species is determined by the relationship of kinship both evolution, as well as the history of its ancestors.
2. Based on the role or function, namely the determination of species is based on the similarity of its role in the environment.

Based on the unique nature and the nature of each individual, the population has the following characteristics:
1. Density or density or density
Density is the size of the population in units of space or volume, which in general the size of the population is represented by individual counts, or biomass of population per unit of space or volume.
2. Birth rate (natalitas)
Natality is the reproduction of new individuals in the population through birth, germination / division.
3. Mortality (mortality)
Mortality is the number of individuals in the population who die for a certain period of time.
4. Genetic
5. Age structure
Is an important population trait affecting both natality and mortality. Motalitas usually vary by age and very dry breeding abilities are limited to certain age groups.
6. Biotic potential
Biotic potential is the potential of the number of populations in a region / ecosystem that is influenced by a living factor, encompassing all living things on earth, both plants and animals.
7. Form of growth
Dissemination / displacement of the population ie the movement of individuals or cultures into or out of a population or population area, also influence the form of growth and the density of the population concerned together with the natalitas and mortality. There are three distribution / displacement of population that is (1) emigration that is movement out, (immigration) movement into and which (3) migration that is go (exit) and return (enter periodically).

B. Population growth
Population growth is a central process in ecology. Since there is no population that grows continuously then we know the existence of population settings. The interaction of species such as predators, competition, herbivory and diseases impacting pop growth and population growth leads to changes in the structure of communities therefore it is important to know how a population grows.
A population released in an appropriate environment will continue to increase in number
In the living circle of the organism there is a phase of birth, growth, adulthood, old and then dead. In the ecology of Boden Heimer (1938) divides animal life in three periods, namely the preductive phase, where animals experience rapid growth but have not been able to produce, reproductive phases, in which animals are able to reproduce, post-reproductive phase, where animals are no longer able to reproduce ie at age old.

Population Growth Model
1. Continuous Time Model is a model used to determine the number of plants that exist in some future time. In this model the individual develops are not limited by the environment such as competition and the limitations of the food supply. The rate of population change can be calculated if the number of births, deaths and migrations is known. The prediction that population numbers will grow continuously was first initiated by Malthus (1798). Population dynamics can be approximated by this model only for short periods of time only.
Continuous models can be accumulated using the equation:

Nt + Dt = Nt + B + I-D-E

Nt: the number of plant populations present in time t.
B: the number of births per unit of time
I: number of arrivals per unit of time
D: the number of deaths unity of time
E: the number of outgoing populations per unit of time.
Nt + Dt: population at time t + Dt.

2. Matrix model
One of the most commonly used growth models by demographers is Leslie's matrix model, developed in the 1940s. This model explains reproduction growth in plant populations. In this model the reproduction of plants is divided into classes or mathematically,
Thus if we know the initial distribution of x (0) and Leslie (L) matrix, then we can determine the distribution of the reproductive age of the plant at any time in the future.

3. Stadia Versus Age
Classical demographic theories use age as the basis for estimates of fertility and survivorship, but age can not be an indicator of reproductive status in plants. There are 2 main points for this, namely:
A. Size does not need to be age correlated
B. Many plants will bloom when they reach a certain size regardless of age.

4. Live Table
There are two kinds of live tables depending on the length of life of individuals in the population:
1. A dynamic table. It is used by observers to follow the growth of germination at certain times until all individuals die
2. Static live tables. A table that measures the age structure of a population to estimate survival patterns of various age groups in a population.

5. Survivorship Curve
That is the number of survivors at each age interval of time will result in a survivorship curve.
There are 3 types of survivorship curves that present extreme population responses:
Type 1: Survivorship curves are characteristic of organisms with low mortality in young stadia and rapid mortality in old age.
Type 2: straight line, where the probability of death is substantially the same at any age.

Type 3: a typical organism that has a high mortality rate is high, followed by mortality of seeds due to the eating of fruits and seed eaters.

6. Fecundity
Fecundity in general means the ability to reproduce. In biology, fecundity is the actual rate of reproduction of an organism or population measured by the number of gametes, seeds, or asexual propagules. In the field of demography, fecundity is the potential reproductive capacity of an individual or population. Fecundity is under genetic and environmental control and is the primary measure of a species's biological fitness. It is also called the specific age of individual birth rate or natality as measured by counting the total number of seeds produced during each age interval and divided by the number of living individuals.

7. Supporting Capacity
Given the existing restrictions, we can estimate that the environment has a carrying capacity, ie the number of individual species that the environment can support. Carrying capacity can be determined not only by the number of individuals in the population, but also by the size and rate of individual growth in the population.

8. Population Rules Dependent Density.
Dependent density is the number of individuals per area of ​​a particular area whose existence is affected by the circumstances affecting it.

9. Dependent Population 

Dependent dependent populations are an ever-increasing population size as predicted by most population growth models, this population is dependent on dependent densities that change in survival or production rates as the population becomes larger. We know that the constant law of Yield in which the plant considers to the gloss not only by density but also to the individual. It is more accurate to say that the plant population is more dependent than the dependent density.