Observing the Ecosystem in the Everglades: Longleaf Pine
Abstract:
Florida is known for its unique landscape and species of animals. Many of the natural parks and preserves are managed and maintained by people. In this sense, the natural parks were actually developed through the planting of West Indian hardwood trees and over 200 species of introduced exotic plants (Webb 1990.). One of the major parks, which is also a heavily studied ecosystem, is called the Everglades. The Everglades is a huge park and natural restoration project which spans over most of South Florida. The Everglades provides a habitat for 45 species of butterflies, 95 species of birds, 20 species of reptiles and common mammals (Dixon and others 2011). For the sake of space and time, the ecosystem of choice will be focused on a tree in a small local park with similarities to the wilderness of the Everglades. First will be discussed the food webs which live on and off the Longleaf Pine tree. Next will be discussed the important organisms. These will be the dominant organisms in the ecosystems food web, mainly the tertiary consumers of the area. After that, energy and ecological efficiency is explained by analyzing the trophic levels. Lastly, an inference of residence time will be described using the in-text reference guide as well as other sources for estimation.
Webs in a Tree:
The Everglades is a huge freshwater marsh which has been impacted by flooding and natural phenomena (Dixon and others 2011). However, human influence has also highly effected the parks and recreational areas. The altered ecosystem has the same food web as an undisturbed ecosystem, but a lot less species to cover. To begin with, trees are the main source of food for the ecosystem. Dozens of fungi live in the roots of the trees. For example, the lichen lives in a very fragile mutualistic relationship with a tree (Hawkes and Menges 2003). Trees support the life of many insects and house animals such as raccoons and squirrels. On one tree, such as the Longleaf Pine, their lives over 100 different insects (Dixon and others 2011). Caterpillars such as the pine devil moth and inch worm eat the pine needles of the tree. The pine webworm hides inside a nest made of caterpillar droppings and needles then pulls them in to eat. Other insects feed on the sap and needles of the tree. The carpenter and harvest ants forage on the tree and collect groups of aphids. The aphids suck up fluids from the tree and then the ants drain the aphids. The larger creatures such as banana spiders and small wood peckers, live in or around the tree to feed off the grub.
Important Organisms:
Insects make up most of the organisms in this ecosystem. Insects and other invertebrates are primary consumers which eat the leaves of the tree, lay eggs under the barks and along the leaves and feed on the pollen (Lindeman 1942). Thanks to them, insect eaters can thrive. Spiders, such as the banana spider, are secondary consumers which make their webs high up in the trees, collecting dozens of insects to feast upon. More dominant creatures such as sapsuckers, woodpeckers, nuthatches, bluebirds, kestrels, wood ducks, squirrels, frogs, salamanders, lizards, snakes, skunks, moles, shrews, foxes and possums are secondary consumers which benefit from the immense insect population in this area (Webb 1990). These insect eaters are key to protecting the trees from being eaten completely. However, other animals (tertiary consumers) prey on the insect eaters in this ecosystem as well. In the Everglades, the raccoons, hawks, shrikes, owls, snakes, foxes bobcats and weasels contribute to the food chain. In particular, the main predators which are dominant in this area are raccoons, hawks, snakes, and foxes. However, with human influence, most of the dominant predators are only seen at night if at all. I have personally seen raccoons and hawks in this area. The raccoons are tertiary consumers which would eat anything including the remains of other animals or attack smaller ones like frogs, and lizards. Hawks are tertiary consumers which eat snakes, rodents, lizards, frogs and other secondary consumers. (Feldman 2016)
Energy and Ecological Efficiency:
Energy comes from one major primary source on Earth and that is the Sun (Smith and Smith 2012). The path of light which travels to the trees, through photosynthesis, creates glucose from water and carbon dioxide. Carbon is one way to track the cycle of energy through the ecosystem. The exchange of carbon dioxide is also a function of autotrophic and heterotrophic respiration. The carbon dioxide is absorbed through the trees stomata and released in respiration as oxygen. The carbon dioxide can come from animal feces, or decaying matter, as well as man-made machines (Gholz , Moncrieff, Loescher1999). It is then released into the atmosphere and back to the earth as it gets reabsorbed and released in a cycle. Through the pine ecosystem, the decaying matter creates nutritional biomass in the soil which then breeds healthy trees (Gibson and Smith 2008). Tree height is determined by absorption of sunlight and a balance of carbon to restore itself. Lichens are another organism which need balance, sunlight and water is its key to its survival. A lichen is an organism which a fungus (decomposer) and algae (producer) cooperate together. The algae captures the suns energy, making sugars for the fungus to survive. The fungus dissolves mineral nutrients from the substrate into fluid so that the algae can take up and prevent dehydration (Gibson and Smith 2008).
The tree (producer) acts as a habitat for the lichens as well as food for other animals. The tree allows primary consumers (ants, caterpillars, beetles) to eat its leaves, produce energy and carbon dioxide. Ten percent of their energy of the Sun goes to the birds, lizards and frogs (secondary consumers). The tertiary consumer has ten percent of that energy left by consuming the secondary consumer (Smith and Smith 2012). However, there are not that many tertiary consumers, only raccoons and hawks in the area which do not seem to find their source of food in secondary consumers. Eventually the tertiary consumer decays and is consumed by decomposers, breaking the rest of that energy into the soil for nourishing the tree. Ecological efficiency is based on the balance and connection in the trophic levels of the food web. Since the tertiary consumers are limited to only two species, the secondary consumers are over run. This is very evident as there are more lizards then raccoons or hawks seen in the area. Instead of being consumed by the hawks and raccoons, the lizards are thriving and multiplying each day. This may be due to the human impact of modern day restaurants and garbage nearby.
Residence Time:
The residence time in this ecosystem refers to the efficiency of energy that reaches each trophic level within the natural structure. The energy transit time from the absorption of carbon through animals and trees varies according to the trophic levels. The residence time is calculated in litter accumulation over the rate of litter fall a year (Smith and Smith 2012). However if there is an abundance of carbon dioxide in the air from too many animals in one level may make the residence time to transfer the carbon dioxide into oxygen at a longer rate (Gholz , Moncrieff, Loescher1999). As we move up the trophic levels, the secondary consumers are over abundant. The secondary consumers, lizards, are plentiful and consume the primary consumers at a high rate. They would eat the insects which would reduce the destruction to trees and increase lichen growth (Hawkes and Menges 2003) . However the heterotrophs such as the hawks and raccoons seem to get their nourishment from human sources and proliferate the consumption of insects, leaving little food left for spiders and other birds. Considering the climate and accumulation of biomass, the residence time can change at any rate. According to figure 10-4, the swamp and marshland residence time is six years (Smith and Smith 2012). This is a rough estimate because it only includes plant biomass and not dead organic matter. There are times when the ecosystem experience too much sunlight and too much rainfall. This effects the balance in the ecosystem by not providing enough food at times for plants and primary consumers. This can affect the productivity in the trophic levels and cause too much carbon from decaying matter. In turn it may increase the residence time when there is little rainfall, from six years to ten years. Although the ecosystem has a six year residence time, it is still thriving with plenty of small creatures which are protecting and nourishing the trees.
References
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