- The exponential and logistic growth patterns are similar in that in both there is a general rise in population as time goes by. With time, the number of people or organisms in that ecosystem keeps increasing as a consequence. In the exponential case, growth is continuous, it continues to infinity. The curve is J-shaped reflecting that should more time be allowed for the experiment/process lengthened, the number of organisms would continue increasing because in this case, the only factor that affects growth is the rate of births. If it is high, the population will always be increasing up to infinity. The exponential growth pattern assumes that there is an unlimited supply of commodities necessary for life. Examples include food, water, air, space and land among others that are necessary to sustain life. For this reason, every generation has enough of these. Access to resources is not a limiting factor in the exponential case of growth of a population (Levy, Matthew, and Joshua Tasoff 545-583). On the other hand, the logistic pattern is S-shaped indicating that initially, there is a small change in population; organisms are reproducing at a slow rate. This is probably because they have not adapted to this ecosystem. After this phase, a steady rise in population is observed. This indicates a high birth rate and presence of abundant resources. But with time, there a stationary phase and a decline phase are observed because resources become scarce, for instance, the carrying capacity has been reached. In a logistic pattern, environmental factors crucial to population growth. At this point, environmental resources have been depleted leading to death of a portion of the existing organisms. Further additions to population past the carrying capacity will lead to a fall in the overall population because of a higher death rate (Mirman 2015).
- For a population to achieve an exponential growth pattern, there must be an unlimited supply of resources. These include space, oxygen, air, water among others. This leaves birth rate to be the only factor influencing population growth. The logistic pattern is more realistic in the nature because there is never an overly adequate supply of resources. There is always scarcity or just adequate for the living ones. At some point in time, the population will overwhelm available supplies impeding further growth. This has been ascribed to the idea of carrying capacity. A given environment has only enough resources to contain a certain number of organisms. Beyond this, excess pressure will be put on the surrounding leading to inadequacy. Some organism will die causing stagnation or even a decline in the population.
- As earlier mentioned, in the exponential case, there is an overwhelming resource supply. If the population is not controlled, it will keep increasing infinitely to a point that it will be undesirable or destructive. If population growth is not regulated in the logistic pattern, there will be a drop. Further rise in population will exert more pressure on the existing resources. The number of organisms will drop because of an increased death rate.
- Birth rate is a major determinant of population growth in any setting. In the exponential pattern, for there to be an increase in population, the birth rate must be more than 1. If the value is 1, it means that upon death, the organism is only replaced in the new generation; there is no change in total tally. If the value is 2 or above, there will be a rapid rise in the population. If this value is less than 1, for example, 0.2, a drop in the sum total will be recorded. If this trend of 0.5 birth rate is continued, the population will become extinct. In the logistic pattern, the same occurs. A high positive birth rate causes a steady increase while a negative one causes a decrease in the total number. A low birth rate is more desirable since it will achieve rise in population but at a slow rate. This is easily sustainable by the surrounding and the administrative authorities at large. A slowly increasing population allows adaptation or changes in the environment to sustain the next generation. Rapidly growing populations reach their maximum faster exerting pressure on available resources after which a decline will be recorded.
- The lesser snow geese are a migratory. They migrate from the Arctic tundra to the warm winter belt and then back to their original destination. The arctic tundra involves regions in Greenland, Alaska, parts of Canada and parts of Siberia. This region contains highly saline soils with a robust vegetation consisting of grass and shrubs. The vegetation is mainly deep-rooted grass (Van der Kolk 6229). This forms the breeding site for the lesser snow geese during spring and at the start of the winter season. The birds burrow into the soil and build nests. They use the present vegetation, in most cases, to build nests. They lay eggs which hatch after about 25 days. After this, the young ones are fed by their parents. The birds will then migrate to the warmer regions in a bid to avert the adverse winter conditions. Areas favored mostly are British Columbia, parts of United States and Mexico. In these regions, their main source of food is leftover grain in fields. These include wheat and maize. At the start of spring, these birds migrate back to the Arctic tundra. These two ecosystems that are inhabited by the lesser snow geese are extremely abundant owing to their extensive vastness. Over the recent years, a staggering increase in their population has been recorded and this has posed concern to researchers, environmentalists and scientists at large. This is entirely a natural phenomenon. The large population of lesser snow geese has caused adversities on these ecosystems. In the Arctic tundra regions, vegetation has been cleared because the birds are digging more into the soil when they are building their nests and once the grass is uprooted, it takes long to reestablish owing to the existing hypersaline conditions that characterize this area; soils in this region contain high concentrations of salt. Initially, it was thought that depletion of vegetation in these regions would result in death of some birds causing a drop in their population. This was not the case since these birds colonized new areas such as marshy regions, rivers and fed on the vegetation present there. In the warm winter regions, birds have moved further inward on people’s farms destroying cultivated grain.
- The graph plotted indicates a general increase in the lesser snow goose population over the years. The curve shows most features of the normal logistic population pattern, for instance, lag phase, exponential phase and an overshoot phase that is unique to this population. The overshoot suggests a constant sharply rising population especially between the year 2012 and 2014. There was a population increase from 3250 to 5500. This translates to a positive population growth of +2250. This also translates to a growth rate of 750 lesser snow geese per year. This is a staggering figure for a population. This overshoot phase reflects characteristics of an exponential population growth pattern in which the only determinant of growth is the rate of birth. The geese lay abundant eggs which hatch in a period of about 25 days. They are fed by both parents, mature and develop into adults. Given the vast nature of the ecosystems that they inhabit, for instance, the Arctic tundra and areas that experience warmer winters, the goose population increases at a high rate. The environment provides an unlimited supply of resources. There have been attempts to reduce the geese population to a smaller figure. It is possible to achieve a population dieback/ crash if some of the measures proposed are put into place.
- The exploding lesser snow goose population poses a high risk to the arctic ecosystem. Destruction of vegetation and colonization of new areas such as marshes and rivers indicates a significant change in the environment. In an effort to mitigate this issue, hunting restrictions have been relaxed to allow hunters to kill some of these birds. Hunting restrictions were initially instituted to curb killing of these species whose population had sharply decreased to a point where the lesser snow goose was classified as an endangered species. Currently, killing of these birds may help reduce the high population (Lefebvre 262-274). Attempts have also been made to commercialize goose meat. This may serve as a boost to encourage hunters to kill more birds. Preparation of goose meat entails a lot of cleaning that is considered tedious by most people. Even so, goose meat is lean and may not meet a high market demand. Though this may not effectively reduce the population, since there is a limit to the number of birds that people can hunt, it is a good strategy. Other measures that have been proposed are poisoning of birds in their nesting regions, using electronic calls, baiting and concealment in the spring season. Though these measures raise crucial ethical concerns, they may contribute heavily to reduction of the goose population to that manageable by the available environmental resources. Another measure that can be undertaken is environmental conservation. This can go a long way in maintaining the arctic vegetation sparing it from further destruction. Climate change has also been considered an effective subject to consider in this situation. Climate change has led to reduction of the tundra vegetation. This has in a way contributed to the destruction of Arctic regions. Implementation of strategies aimed at averting climate change may help reestablish the Arctic vegetation preventing the destruction observed.
Lefebvre, Josee, et al. “The greater snow goose Anser caerulescens atlanticus: Managing an overabundant population.” Ambio 46.2 (2017): 262-274.
Levy, Matthew, and Joshua Tasoff. “Exponential-growth bias and lifecycle consumption.” Journal of the European Economic Association 14.3 (2016): 545-583.
Mirman, Daniel. Growth curve analysis and visualization using R. CRC Press, 2016
Van der Kolk, Henk-Jan et. al. “Potential Arctic tundra vegetation shifts in response to changing temperature, precipitation and permafrost thaw.” Biogeosciences 13.22 (2016): 6229