I'm the fourth in a brood of four. My father was a son of a public school teacher and a municipal treasurer in Leyte. The didn't have much except for the drive to be educated. My mother comes from a family with vast lands, inherited from a geodetic engineer grandfather from Cavite who married a bagobo datu's daughter. My own grandfather was a farmer, pastor and police major rolled into one while my lola is a housewife running almost 30 hectares of land.
.
I was born in Davao City but grew up in Manila until my father was killed during a drug bust somewhere in Quezon City. I could still remember the days in Manila when my Lola from Davao sends one sack of rice for us in Manila. When papa died, life was not easy so me and my sister were sent back to Davao - this was the beginning of green and armed life.
.
Lolo had his farm planted with coconut trees. On Sundays (oh how I hated Sundays!), me and my sister are sent to the farm (we were living in the City because of the NPA) to plant coffee. When our coffee trees bore fruits, we were again sent every harvest. My mom helps when she's in Davao leaving her police work in Manila for a while. During our harvest, lolo was held at gunpoint by some NPAs and they took his gun. There was then another harvest that took us so late we cannot go back to the City anymore. My sister, lola and I had to sleep under the piano for fear the the NPA might notice there are people in the house and they might burn the house down.
.
Years passed and mama was transferred to Davao City and NPA was moved farther to the north away from our farm. We then stayed more and more at the farm. Night at the farm was always fun filled with aninipot - FIREFLIES!!! Lola said that when a tree is filled with fireflies, taw-an daw (not like ours live there). We had HUGE chicken called caber. We could eat all the eggs we want. And 20 or so cows run in the farm with 3 albino carabaos. When it's mango harvest, people hung on mango trees like monkeys! Mama said one time that there lived a white monkey in our farm. To avoid my dismay since I could not find a white monkey, mom asked our trabahante to get a mi-lo (wild cat) for me and my sister. My unforgetable day was when a til-as (I really don't know its name in english! it is a hairy insect that lives in a talisay tree) managed to creep into my shirt! I had red itchy rashes all over my body! I also got stung by a bee. A big santol fruit dropped on top of my head during another harvest. Lola runs with a pamalo after me when I opened most of the coconut fruits (supposedly for copras) looking for buwa. There was also this one time when I could not open my mouth because of the dagta from a star apple fruit! I was dirty, I was happy, I was with nature.
.
Now ten years later, my 6 year old cousin living in our farm does not even know what an aninipot is! She could not freely stroll in the farm because a 4 meter road was constructed somewhere in the middle of it. We lost our santol trees because my aunt decided to sell it as wood. Mama, the farmer in their brood, decided to keep two santol trees in her farm lot. We don't have a cow now. The talisay tree is cut - I somehow missed the til-as. My uncles decided to have their shares rented by rooster owners. So most of the 30 hectare land are now filled with rooster for sabong. The star apple trees were ALL cut by the rooster owners. They even cut down some of the coconut trees my lolo planted. The river running in the middle of the farm now overflows everytime it rains!
.
When I look back, I feel that nature would have been better off with NPA than with my uncles. I'm with the fourth generation who will manage a little share on the farm. The diversity of organisms in our farm has deteriorated within a short span of time between my lolo and me. White monkeys were lost. Aninipots were lost. The farm is now surrounded with subdivisions while inside it are sabungan. I fear that one day, I will not leave anything green for my children, just like what the 2010 biodiversity clip has shown -- maybe children will just look at plants and animals in a video. Lucky if it were to happen. I beleive, when the balance of nature is tilted as plants and animals species become extinct, humankind will soon follow. We will lose the source of our economy, the source of our basic needs, and the thing that gives us a liveable atmosphere.
Friday, March 4, 2011
Thursday, March 3, 2011
Energetics
Energetics is quite an amazing story about the path of energy from the sun going to how this energy supports life. No wonder why ancient people once thought of the Sun as God!
.
.
.
.
.
.
.
Ecosystems, Wikipedia says, exist and operate by virtue of a flow of energy through the components of the system and thermodynamics forms the very basis of the biosphere.
Biosphere is the part of the Earth that supports life. It is basically composed of all the waters in the world where we find aquatic plants, animals and protists; all the land masses of the world where terrestrial living organisms thrive; and the atmosphere that surround the earth where birds fly.
Going back to energy: All Earth’s energy comes from the large ball of fire which we were introduced to as the Sun. Here, I’m going to discuss two energies that come from the Sun which supports life on Earth. Our understanding of these concepts would make us appreciate the value of interrelationship among living and nonliving things.
Sun gives off LIGHT ENERGY. This light energy sets up the process called photosynthesis. In photosynthesis, inorganic compounds such as carbon dioxide and water are “processed” with the help of light energy into food. When we are hungry, we do not have energy to do work. Now, energy from the sun is stored as potential energy in the form of “food” - particularly in the chemical bonds of C6H12O6 – in plants. Herbivores harvest this energy from plants through eating… and there goes the chain of predators in the food chain where energy is passed from the first trophic level of plants to the next and the next trophic levels.
Sun also gives off RADIANT ENERGY or energy of electromagnetic waves. This energy brings HEAT ENERGY which causes winds and current. Remember that the earth experiences differential heating because of its shape and its tilt. Winds and current cause brings KINETIC ENERGY – energy in motion. Also, because of heat, warming results in the evaporation of water. Therefore, hydrologic cycle is triggered. POTENTIAL ENERGY is possessed when water evaporates and begins to be stored in the clouds. As it falls back down to Earth, we have energy in the form of KINETIC.
If we put the key concepts of Food chains and energetics together, we could justify the importance of eating veggies! Veggies have more energy since they are in the first trophic level!
Monday, February 28, 2011
FOOD CHAINS AND FOOD WEB
FOOD CHAINS AND FOOD WEB
I learned food chains and food webs on my third grade in Davao City Special School. Basically, it is a representation of the relationship between organisms in complying with their need for nourishment. Now it is clearly established that it is a predator-prey relationship where one gets eaten. In high school, first year, I had a wrong answer to my teacher’s question as to which trophic level contains the most energy. I answered the eagle (the one on top) because it was bigger (hahaha!). My misconception was corrected by my Biology teacher, who also influenced me to take up Biology in College.
The idea of food chains and food webs, as well as conditions and resources, biotic and abiotic factors, habitat, and succession points out a clearer picture of ecology – that is INTER RELATIONSHIP. I’ve been saying that the study of ecology brings with it its complex nature. But ecology is unlike a circle, at some point in its complexity, one can begin at a certain point to try and understand it even with only 10% of our brains is utilized.
Early proponents thought that the Earth is the center of the universe. This misconstruction is also similar to man as the supreme creation by which all the rest of organisms should be of service to or should benefit humans. We may have been given higher form of intelligence, but it does not mean we can take away as much as what we can from nature (this includes all other organisms). Similarly, man should not live like how he lived in the stone ages. The point here is more on balance – SUSTAINABLE DEVELOPMENT. Wikipedia defines sustainable development as a pattern of resource use that aims to meet human needs while preserving the environment so that these needs can be met not only in the present, but also for generations to come.
Food chains and food webs can be used as key to sustainable development. These two could serve as a guide as to which resource could we take much from without tilting the balance of nature. Let’s begin at the bottom of the food chain/web/pyramid.
Those organisms at the bottom are called producers. These producers are all AUTOTROPHIC such that they can manufacture organic food from inorganic matter. Most producers are photosynthetic – they harvest energy from the light to be used for food conversion. There are also those that are chemosynthetic – they manage to manufacture food without sunlight. Since we follow organic substances in the form of food, we are likewise following carbon. Organic compounds are composed of carbon (bonded to hydrogen). But not all carbon containing compounds are organic, such as carbon dioxide. The key here is hydrocarbon bond – if there’s a hydrocarbon bond, then it’s organic (except urea).
Producers are fed upon by other organisms. Those who feed on producers are herbivores (or omnivores) and they occupy the second trophic level. After that follows the higher trophic levels with bigger organisms in it.
Given this chain, who gets to control the proliferation of the chain? Should it be the producers who are at the bottom, or should it be the higher consumers who are on top. Ecologists choose one of these two pints: bottom up control or top down control.
In the bottom up control, the organisms on the lower trophic level get to control the productivity of the bigger ones – sounds like David and goliath! Example, if the resources for plants to grow are limited, then the productivity of these producers are controlled. The herbivores feeding on plants has little influence on these producers. If nutrients abound, plant productivity becomes high thereby supporting larger numbers of herbivores.
In the top down control, (this I like!) the organisms on the higher trophic level controls the productivity of those lower to it. This concept is otherwise referred to as trophic cascade. Imagine yourself to be on the fourth energy level. Man eats the bigger fish. Bigger fish eats smaller fish. Smaller fish feeds on planktons. If man exerts more control by eating more bigger fish to the point that the latter’s population significantly decreases, this puts lesser pressure on smaller fish. The smaller fish in turn increases in population. Because of its increase in population, it will consume more of the planktons. An amazing relationship!
Conservation as well as consumption will be maintained at a less harmful level if man is able to identify the intricate relationships of organisms. After all, life is not just about money or comfort as these two things could be washed away by a single tsunami. Relationships are of more vital role to our biodiversity which in turn ensures our very own existence.
I learned food chains and food webs on my third grade in Davao City Special School. Basically, it is a representation of the relationship between organisms in complying with their need for nourishment. Now it is clearly established that it is a predator-prey relationship where one gets eaten. In high school, first year, I had a wrong answer to my teacher’s question as to which trophic level contains the most energy. I answered the eagle (the one on top) because it was bigger (hahaha!). My misconception was corrected by my Biology teacher, who also influenced me to take up Biology in College.
The idea of food chains and food webs, as well as conditions and resources, biotic and abiotic factors, habitat, and succession points out a clearer picture of ecology – that is INTER RELATIONSHIP. I’ve been saying that the study of ecology brings with it its complex nature. But ecology is unlike a circle, at some point in its complexity, one can begin at a certain point to try and understand it even with only 10% of our brains is utilized.
Early proponents thought that the Earth is the center of the universe. This misconstruction is also similar to man as the supreme creation by which all the rest of organisms should be of service to or should benefit humans. We may have been given higher form of intelligence, but it does not mean we can take away as much as what we can from nature (this includes all other organisms). Similarly, man should not live like how he lived in the stone ages. The point here is more on balance – SUSTAINABLE DEVELOPMENT. Wikipedia defines sustainable development as a pattern of resource use that aims to meet human needs while preserving the environment so that these needs can be met not only in the present, but also for generations to come.
Food chains and food webs can be used as key to sustainable development. These two could serve as a guide as to which resource could we take much from without tilting the balance of nature. Let’s begin at the bottom of the food chain/web/pyramid.
Those organisms at the bottom are called producers. These producers are all AUTOTROPHIC such that they can manufacture organic food from inorganic matter. Most producers are photosynthetic – they harvest energy from the light to be used for food conversion. There are also those that are chemosynthetic – they manage to manufacture food without sunlight. Since we follow organic substances in the form of food, we are likewise following carbon. Organic compounds are composed of carbon (bonded to hydrogen). But not all carbon containing compounds are organic, such as carbon dioxide. The key here is hydrocarbon bond – if there’s a hydrocarbon bond, then it’s organic (except urea).
Producers are fed upon by other organisms. Those who feed on producers are herbivores (or omnivores) and they occupy the second trophic level. After that follows the higher trophic levels with bigger organisms in it.
Given this chain, who gets to control the proliferation of the chain? Should it be the producers who are at the bottom, or should it be the higher consumers who are on top. Ecologists choose one of these two pints: bottom up control or top down control.
In the bottom up control, the organisms on the lower trophic level get to control the productivity of the bigger ones – sounds like David and goliath! Example, if the resources for plants to grow are limited, then the productivity of these producers are controlled. The herbivores feeding on plants has little influence on these producers. If nutrients abound, plant productivity becomes high thereby supporting larger numbers of herbivores.
In the top down control, (this I like!) the organisms on the higher trophic level controls the productivity of those lower to it. This concept is otherwise referred to as trophic cascade. Imagine yourself to be on the fourth energy level. Man eats the bigger fish. Bigger fish eats smaller fish. Smaller fish feeds on planktons. If man exerts more control by eating more bigger fish to the point that the latter’s population significantly decreases, this puts lesser pressure on smaller fish. The smaller fish in turn increases in population. Because of its increase in population, it will consume more of the planktons. An amazing relationship!
Conservation as well as consumption will be maintained at a less harmful level if man is able to identify the intricate relationships of organisms. After all, life is not just about money or comfort as these two things could be washed away by a single tsunami. Relationships are of more vital role to our biodiversity which in turn ensures our very own existence.
Habitat Fragmentation
HABITAT FRAGMENTATION
The essence of habitat fragmentation lies on our genuine understanding of the value of BIODIVERSITY. Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet (Wikipedia). Biodiversity is a measure of the health of ecosystems. Biodiversity is measured in terms of species richness, population ab
undance and distribution, and genetic diversity. Our concern on biodiversity and our interest on habitat fragmentation meet on our CONSERAVATION goals. Given our conservation goals, we want to establish the effects of habitat fragmentation on biodiversity.
The essence of habitat fragmentation lies on our genuine understanding of the value of BIODIVERSITY. Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet (Wikipedia). Biodiversity is a measure of the health of ecosystems. Biodiversity is measured in terms of species richness, population ab
undance and distribution, and genetic diversity. Our concern on biodiversity and our interest on habitat fragmentation meet on our CONSERAVATION goals. Given our conservation goals, we want to establish the effects of habitat fragmentation on biodiversity.Biodiversity is indirectly measured by habitat loss. What is habitat? How do we determine that a habitat has been lost?
Habitat is more than the landscape or the area. It constitutes the resources and conditions present in an area that produce occupancy, including survival and reproduction, by a given organism (Krausman, nd). In a previous blog entry, we have exemplified the Monfort bat cave as the habitat of fruit bats. This habitat offers refuge for the bats to sleep, be protected and able to reproduce, including easy access to foraging sites.
A habitat is lost once an area is no longer able to provide the resources and conditions which enable organisms to thrive in it. It is determined quantitatively when population growth rate of species decrease, when trop
hic chain lengths are reduced, when species interactions are altered, as well as when breeding success, dispersal success, predation rate, foraging success rate are reduced. This, generally, is the concept of HABITAT LOSS. Habitat loss is erroneously equated with HABITAT FRAGMENTATION. Farig (2003) clarified that HABITAT LOSS occurs with fragmentation while fragmentation may occur with no habitat loss..
.
.
What then is HABITAT FRAGMENTATION? Several studies, specially those richly discussed by Farig, give different definitions of habitat fragmentation.
.
What then is HABITAT FRAGMENTATION? Several studies, specially those richly discussed by Farig, give different definitions of habitat fragmentation.
.
HABITAT FRAGMENTATION occurs when a large expanse of habitat is transformed into a number of smaller patches of smaller total area, isolated from each other by a matrix of habitats unlike the original (Fahrig, 2003). Imagine New York City, particularly its skyscrapers and the well-known Central Park. Suppose the island of New York, prior to the construction of skyscrapers, is composed of the flora and fauna found in central park. After sometime, because of advances in both technology and demands of human existence, Americans started to occupy lots in New York City by cutting down trees. This is habitat fragmentation in the landscape level. The habitat of the entire island has been reduced to patches, and the matrix would be composed of skyscrapers.
.
According to Franklin (2002) HABITAT FRAGMENTATION is the disruption of once large continuous blocks of habitat into less continuous habitat. It is the breaking up of a large intact area of a single vegetation type into smaller intact units (called patches). A habitat is measured in terms of configuration (size, shape) and habitat amount (or lack of habitat). And when this habitat undergoes fragmentation, the degree of fragmentation is measured in terms of patch size (which researchers report as ambiguous), patch isolation and reduction in habitat (simply habitat amount).
.
.
The effect of habitat LOSS to biodiversity is crystal clear. When habitat is lost, biodiversity is also lost. However, the question on the effect of habitat fragmentation on biodiversity is not clearly established.
Habitat fragmentation has the following effects (not directly to biodiversity): (1) reduction in habitat amount, (2) increase in number of habitat patches, (3) decrease in sizes of habitat patches and (4) increase in isolation of patches.
.
The effect of habitat LOSS to biodiversity is crystal clear. When habitat is lost, biodiversity is also lost. However, the question on the effect of habitat fragmentation on biodiversity is not clearly established.
Habitat fragmentation has the following effects (not directly to biodiversity): (1) reduction in habitat amount, (2) increase in number of habitat patches, (3) decrease in sizes of habitat patches and (4) increase in isolation of patches.
.
.
Reduction of habitat is almost similar to loss of habitat. A 10 hectare land habitat when disturbed by human activities such as 2 hectare subdivision, habitat worth 20% of the previously established is lost.
.
Reduction of habitat is almost similar to loss of habitat. A 10 hectare land habitat when disturbed by human activities such as 2 hectare subdivision, habitat worth 20% of the previously established is lost.
.
.
The last three referring to patches actually have impact on the change in habitat configuration, although, careful analysis projects that these are also related to habitat reduction. One thing is for sure though, habitat loss and habitat fragmentation both result in smaller patches. PATCH ISOLATION is measured in terms its distance to the next nearest patch.
.
The last three referring to patches actually have impact on the change in habitat configuration, although, careful analysis projects that these are also related to habitat reduction. One thing is for sure though, habitat loss and habitat fragmentation both result in smaller patches. PATCH ISOLATION is measured in terms its distance to the next nearest patch.
.
.
Given these four effects of habitat fragmentation, we can establish the effects of habitat fragmentation on biodiversity. Habitat fragmentation is quantized by measuring a range of variables including abundance, density, distribution, reproduction, movement and species richness. Research findings show that birds had lower reproductive rates in small patches than in large patches. Also, fragmentation leads to a larger number of smaller patches. Smaller number of patches means more edges(this is analogous to surface area). Along the edges, there might be increased predation.
On the positive side, a research found a positive effect of fragmentation on butterfly species richness. Within this patches, preys may find isolation that would protect them from predators. This is a venue for them to increase their number. Coexistence of two competing species could also be extended by dividing the habitat (effect of fragmentation) into smaller patches.
Given these four effects of habitat fragmentation, we can establish the effects of habitat fragmentation on biodiversity. Habitat fragmentation is quantized by measuring a range of variables including abundance, density, distribution, reproduction, movement and species richness. Research findings show that birds had lower reproductive rates in small patches than in large patches. Also, fragmentation leads to a larger number of smaller patches. Smaller number of patches means more edges(this is analogous to surface area). Along the edges, there might be increased predation.
On the positive side, a research found a positive effect of fragmentation on butterfly species richness. Within this patches, preys may find isolation that would protect them from predators. This is a venue for them to increase their number. Coexistence of two competing species could also be extended by dividing the habitat (effect of fragmentation) into smaller patches.
What is more interesting also is that habitat fragmentation should be considered in terms of species. A 10 meter wide road constructed in the middle of a rainforest might be harmful or detrimental for insects in terms of their reproduction, survival and food sources but not necessarily for the Philippine eagle.
Our knowledge on the effect of habitat fragmentation will affect on how we design a sustainable working system that would balance with the natural demands of nature. We cannot expect man avoid constructing shelters in faithful consideration of habitat fragmentation. Fragmentation may be allowed considering its weighed advantages and disadvantages. Habitat fragmentation is an indicator for man to know when enough is enough.
Sunday, February 27, 2011
Biological Interactions
BIOLOGICAL INTERACTIONS
"no man is an island" ... I would say no organism is a hermit - ooops! But hermits are organisms too.
Interactions between species and individuals are classified on the basis of the EFFECTS and the MECHANISM of interaction. Here, we discuss some of the different forms of biological interactions and some of its ecological importance.
Living organisms need a supply of energy in order to perform life's vital characteristics such as surviving and reproduction. The most popular source of energy is the sun. However, since not all organisms are AUTOTROPHS, organisms capable of producing food from inorganic substances, others resort to consuming those autotrophs or other organisms. They also establish relationships such as living together and sharing resources.
INTIMATE relationships between species are called symbiosis. This is regardless of whether harm is caused or not.
There are three types of symbiotic relationships: mutualism, commensalism and parasitism.
1. Mutualism: In a mutualistic relationship, both species benefit from each other. An example of this relationship is that between a tagak and a kalabaw. The tagak or the cowbird benefits from the carabao by eating the mites and ticks that live on the latter's skin. Also, the carabao benefits from the cowbird since the cowbird gets rid of the parasitic mites and ticks off the carabao's back. Key: individuals live in close association WITH MUTUAL BENEFIT.
.
.
2. Commensalism: In commensalism, only one organis
m benefits while the other is not affected. A classic example for this kind of relationship is that between clown fish and the sea anemone. Since clown fish are immune from the stinging cells of sea anemone, clown fish can use sea anemone as its shelter. Despite this, sea anemone is not harmed nor befited by the clown fish's presence. Key: Individuals live in close association whereby ONE BENEFITS while the other is NOT AFFECTED.
3. Parasitism: This is a close relationship between two organisms where one benefits while the other is harmed. An example of this relationship is the one that exists between tapeworm and humans. Tapeworm, a parasite, lives inside its host, the human species. Tapeworms gets all the nourishment while depriving the human body of the same. Key: Individuals live in close association whereby ONE BENEFITS while the other is AFFECTED
An organism’s niche includes how it avoids being eaten and how it finds or captures its food. Predators are consumers that capture and eat other consumers. The prey is the organism that is captured by the predator. This relationship is referred to as Predation.
Competition is an interaction among individuals utilizing a limited resource. (Note: If resources are not limited, individuals will have nothing to compete for). Competition results to the reduced fitness of the comepting individuals. Interspecific competition occurs between species utilizing a shared resource but belonging to different taxa. Intraspecific competition exists among members of the same species.
Knowledge on these relationships makes conservation biology more responsive to the demands of biological diversity. What benefits can be obtained from our knowledge of these relationships?
For conservation biologists aiming to prevent extinction of one species, this may be enhanced if they could identify predators of their target species to prevent mortality cases. Also, knowledge on organisms with mutual relationships with their target species, would enhance survival of target species.
Man has also avoided diseases through medical advancement. These medical advancements are made possible by identifying organisms that would prey upon or have unfavorable relationship with those organisms harmful to man.
No organism lives in solitude. One way or another, it would rely on other organisms, be it plants or animals or fungi or protists or bacteria, to comply with its nourishing requirements.
anthropogenic actvities
I was reading HABITAT FRAGMENTATION and a paper on a similar topic but more on avian biology when I remembered my analysis on anthropogenic activities.
.
Let me outline my analysis on anthropogenic activities in the following order: (1) anthropogenic activities; (2) Effects of anthropogenic activities on amount of available resources; (3) effects on viability of resources; (4) effects on level of conditions; and (5) organisms’ response to these effects (changes in resources and conditions)
.
What are Anthropogenic Activities?
.
Republic Act 9729 enacted by the Philippine congress defines anthropogenic causes as causes resulting from human activities or produced by human beings. This was done in our government’s response to threats of climate change. This republic act recognizes the right of the people to a healthful ecology in accord with the rhythm and harmony of nature.
.
Generally, anthropogenic activities mean conversion of open spaces, landscapes, and natural environments by human action. This includes the conversion of forest areas to subdivisions, degradation of forest resources for supplying construction materials to build our homes, and use of terrestrial and aquatic resources to make sure the bellies of the human race will not be empty. .
With this established, one should look into the effects of these anthropogenic activities to nature, specifically (1) Amount of resources (2)Viability of Resources and (3) level of conditions and resources.
.
Let us try to bring anthropogenic activities closer to home to appreciate its impact. When we are born, we add to the population of the human race – hence, we contribute to (1) over population. To comply with our basic needs, we are dressed, fed and physically sheltered. Our clothes are obtained from plants (abaca, cotton), animals (animal skin) or they could be synthetic fibers. For clothes alone, our anthropogenic activities result to consumption of plants and animals. Our food and shelter demands also put these organisms in a losing end. To add to this, we need space to build our shelters and recreational infrastructures. These activities bring about (2) forest degradation, (3) animal extinction, and (4) land use. With our desire to build tough shelters, we use minerals. And we also patronize minerals to satisfy our mundane needs to have jewelry (impact of a stratified community). Hence, mankind has discovered (5) mining in response to his needs. This mining has also resulted to acid mine drainage and mountaintop removal. And with the rise of technology, walking has become out of fashion that we resort to driving our own cars which are ran by fuels– an activity which has brought (6) carbon dioxide emission to a logarithmic increase.
Effects on Amount of Resources
Man’s exploitation of natural resources has paved way to resource depletion.
In Davao City alone, our water, which was recognized as one of the best potable waters based on a study by the American Waterworks Association, was expected to be depleted when one well in Toril began to extract sand – a signal that underground water is no longer abound. Human activities such as taking a bath, drinking water, washing clothes, and responding to fire has depleted our sources of water. (Please note that Davao City Water District is not serving the entire Davao City. It only caters to two districts).
Unrestrained construction of subdivisions has put animals away with the destruction of their habitats. Animals which are natural consumers of insects and parasites are put at risk because of man’s land use. This is best exemplified when rat population increases and they attack rice fields – the rat population was not limited because snakes, rat’s natural predators, are forced deeper into the forests with the increased land use. Similarly, resources obtainable from plants and animals, because of the destruction brought by land use, are also depleted.
Effects on Viability (capable of living) of Resources
Viability is the ability of an organism (or of a particular resource) to maintain itself or recover its potentialities (Wikipedia). The ability of a forest or an aquatic system to recover its potentialities as a resource depends on the time it is given to bring back what was lost. Or, it could recover if the demand from it is not so logarithmic such that depletion could no longer be impeded.
Given the previous example, if our water use is put at parsimony, then ground water could still recover the amount mankind has taken from it. However, if we abuse water use, ground water areas may form into a crater – a form that is no longer recoverable as a water source.
Effects on Level of Conditions
Physical conditions include temperature, humidity, power of Hydrogen (pH), wind speed and water flow. If one would describe the relationship between anthropogenic activities and its effects, the word intricate would be most applicable. Over population, forest degradation, animal extinction, land use, and carbon dioxide emission contribute to the increasing world temperature. Over population implies an increased demand and use of natural resources. Forest degradation carries with it the consequence of losing plants that absorb carbon dioxide from the atmosphere. Animal extinction will bring about death of organisms that are vital in the complex food web that guarantees balance in nature. Land use for industrialization and housing decrease the number of plants per area since land use, still contributing to loss of autotrophic organisms. Carbon dioxide emissions brought by human activities such as burning of fossil fuel add to the injury. Power of Hydrogen (pH) in aquatic areas are lowered because of the toxic wastes released by industries.
Organisms’ response to effects of anthropogenic activities on conditions and resources
Survival, development, and reproduction are among an organism’s main goals. In order to survive, organisms can avoid, tolerate, or specialize in response to the effects on conditions and resources brought by anthropogenic activities.
.
Let me outline my analysis on anthropogenic activities in the following order: (1) anthropogenic activities; (2) Effects of anthropogenic activities on amount of available resources; (3) effects on viability of resources; (4) effects on level of conditions; and (5) organisms’ response to these effects (changes in resources and conditions)
.
What are Anthropogenic Activities?
.
Republic Act 9729 enacted by the Philippine congress defines anthropogenic causes as causes resulting from human activities or produced by human beings. This was done in our government’s response to threats of climate change. This republic act recognizes the right of the people to a healthful ecology in accord with the rhythm and harmony of nature.
.
Generally, anthropogenic activities mean conversion of open spaces, landscapes, and natural environments by human action. This includes the conversion of forest areas to subdivisions, degradation of forest resources for supplying construction materials to build our homes, and use of terrestrial and aquatic resources to make sure the bellies of the human race will not be empty. .
With this established, one should look into the effects of these anthropogenic activities to nature, specifically (1) Amount of resources (2)Viability of Resources and (3) level of conditions and resources.
.
Let us try to bring anthropogenic activities closer to home to appreciate its impact. When we are born, we add to the population of the human race – hence, we contribute to (1) over population. To comply with our basic needs, we are dressed, fed and physically sheltered. Our clothes are obtained from plants (abaca, cotton), animals (animal skin) or they could be synthetic fibers. For clothes alone, our anthropogenic activities result to consumption of plants and animals. Our food and shelter demands also put these organisms in a losing end. To add to this, we need space to build our shelters and recreational infrastructures. These activities bring about (2) forest degradation, (3) animal extinction, and (4) land use. With our desire to build tough shelters, we use minerals. And we also patronize minerals to satisfy our mundane needs to have jewelry (impact of a stratified community). Hence, mankind has discovered (5) mining in response to his needs. This mining has also resulted to acid mine drainage and mountaintop removal. And with the rise of technology, walking has become out of fashion that we resort to driving our own cars which are ran by fuels– an activity which has brought (6) carbon dioxide emission to a logarithmic increase.
Effects on Amount of Resources
Man’s exploitation of natural resources has paved way to resource depletion.
In Davao City alone, our water, which was recognized as one of the best potable waters based on a study by the American Waterworks Association, was expected to be depleted when one well in Toril began to extract sand – a signal that underground water is no longer abound. Human activities such as taking a bath, drinking water, washing clothes, and responding to fire has depleted our sources of water. (Please note that Davao City Water District is not serving the entire Davao City. It only caters to two districts).
Unrestrained construction of subdivisions has put animals away with the destruction of their habitats. Animals which are natural consumers of insects and parasites are put at risk because of man’s land use. This is best exemplified when rat population increases and they attack rice fields – the rat population was not limited because snakes, rat’s natural predators, are forced deeper into the forests with the increased land use. Similarly, resources obtainable from plants and animals, because of the destruction brought by land use, are also depleted.
Effects on Viability (capable of living) of Resources
Viability is the ability of an organism (or of a particular resource) to maintain itself or recover its potentialities (Wikipedia). The ability of a forest or an aquatic system to recover its potentialities as a resource depends on the time it is given to bring back what was lost. Or, it could recover if the demand from it is not so logarithmic such that depletion could no longer be impeded.
Given the previous example, if our water use is put at parsimony, then ground water could still recover the amount mankind has taken from it. However, if we abuse water use, ground water areas may form into a crater – a form that is no longer recoverable as a water source.
Effects on Level of Conditions
Physical conditions include temperature, humidity, power of Hydrogen (pH), wind speed and water flow. If one would describe the relationship between anthropogenic activities and its effects, the word intricate would be most applicable. Over population, forest degradation, animal extinction, land use, and carbon dioxide emission contribute to the increasing world temperature. Over population implies an increased demand and use of natural resources. Forest degradation carries with it the consequence of losing plants that absorb carbon dioxide from the atmosphere. Animal extinction will bring about death of organisms that are vital in the complex food web that guarantees balance in nature. Land use for industrialization and housing decrease the number of plants per area since land use, still contributing to loss of autotrophic organisms. Carbon dioxide emissions brought by human activities such as burning of fossil fuel add to the injury. Power of Hydrogen (pH) in aquatic areas are lowered because of the toxic wastes released by industries.
Organisms’ response to effects of anthropogenic activities on conditions and resources
Survival, development, and reproduction are among an organism’s main goals. In order to survive, organisms can avoid, tolerate, or specialize in response to the effects on conditions and resources brought by anthropogenic activities.
.
With conditions, organisms that are not sedentary (most animals) can move from place to place to avoid changes in temperature (MIGRATION). Animals could also try to tolerate conditions they are not used to. They may also employ some specializations in response to these anthropogenic activities. Among these responses, avoiding may be done immediately should the condition become “harsh” for the species. Tolerance and specialization may need some time and survival of an individual species is put at risk. If one could not tolerate or specialize, then it is by the will of natural selection that an organism is declared “unfit”. Other than these three, conditions may set off a changed response to extreme conditions. This is acclimatization – the ability of an organism to adjust to a new range of environmental temperature over a period of days or weeks. An example for this one is bullhead catfish which, during the summer, could survive up to 36o Celsius but temperature higher than 28oC is lethal during winter. Sedentary organisms, on the other hand, are left with the option to modify their morphological and physiological characteristics parallel to the changes in condition.
With conditions, organisms that are not sedentary (most animals) can move from place to place to avoid changes in temperature (MIGRATION). Animals could also try to tolerate conditions they are not used to. They may also employ some specializations in response to these anthropogenic activities. Among these responses, avoiding may be done immediately should the condition become “harsh” for the species. Tolerance and specialization may need some time and survival of an individual species is put at risk. If one could not tolerate or specialize, then it is by the will of natural selection that an organism is declared “unfit”. Other than these three, conditions may set off a changed response to extreme conditions. This is acclimatization – the ability of an organism to adjust to a new range of environmental temperature over a period of days or weeks. An example for this one is bullhead catfish which, during the summer, could survive up to 36o Celsius but temperature higher than 28oC is lethal during winter. Sedentary organisms, on the other hand, are left with the option to modify their morphological and physiological characteristics parallel to the changes in condition.
.
We should, however, not forget that conditions do not act only on one species. It also acts on the competitors, prey, parasites and predators of a particular species. Therefore, conditions may affect the availability of resources. It could also trigger the spread of diseases and parasites.
On resources alone, its number is depleting because of man’s exploitation of natural resources. Should there be a decrease in the availability of water (precipitation), plants specialize in the form of avoiders or tolerators. Avoiders have short lifespan such that when water is not abundant, they remain dormant as seeds or they shed photosynthetic tissues. Tolerators have developed long-lived leaves which transpire slowly. Plants may also increase the efficiency of water use through C4 pathway (high affinity for CO2 therefore absorb more CO2 per H2O lost) and CAM (crassulacean acid metabolism) where stomata is opened at night cutting the loss of water as against to the rapid H2O evaporation during daytime. Animals on the other hand, when resources are depleting, will have an increased competition depending on the needs of the organism. I have the opinion that polyphagous species will have better chances of survival than monophagous species.
We should, however, not forget that conditions do not act only on one species. It also acts on the competitors, prey, parasites and predators of a particular species. Therefore, conditions may affect the availability of resources. It could also trigger the spread of diseases and parasites.
On resources alone, its number is depleting because of man’s exploitation of natural resources. Should there be a decrease in the availability of water (precipitation), plants specialize in the form of avoiders or tolerators. Avoiders have short lifespan such that when water is not abundant, they remain dormant as seeds or they shed photosynthetic tissues. Tolerators have developed long-lived leaves which transpire slowly. Plants may also increase the efficiency of water use through C4 pathway (high affinity for CO2 therefore absorb more CO2 per H2O lost) and CAM (crassulacean acid metabolism) where stomata is opened at night cutting the loss of water as against to the rapid H2O evaporation during daytime. Animals on the other hand, when resources are depleting, will have an increased competition depending on the needs of the organism. I have the opinion that polyphagous species will have better chances of survival than monophagous species.
Monday, February 21, 2011
Succession
Let's begin our definiton of SUCCESSION based on a more common issue. Succession is generally a series of change - any change that one can think of. Queen Elizabeth II (the reigning queen of United Kingdom), will be succeeded by her son Prince Charles. Prince Charles will be succeeded by his son with Lady Diana, Prince William. This is a POLITICAL SUCCESSION. The ruling/sitting monarchs are CHANGED or REPLACED by succeeding generation - this can be brought about by death or abdication.
In a more local nature, succession can be brought by removal. Political SUCCESSION in the Philippines is very dramatic such as the succession of power from Marcos to Cory Aquino and that from Erap Estrada to Gloria Arroyo. Upon lawful election, political succession peacefully paved way to the succession of Noynoy Aquino.
Bearing in mind that succession is a change which may be brought naturally (such as death) or harsh (such as removal), one can define ECOLOGICAL SUCCESSION as change in ECOLOGICAL COMMUNITY.
Succession generally follows two stages: Primary Succession and Secondary Succession.
.
Primary succession are those in the form of lava flows caused by volcanic erruptions, substrate exposed by the retreat of glaciers and freshly formed san dunes (Townsend, Begon and Harper). The key determinant for a primary succession is that the area is never occupied by a community - "sterile"area.
.
On the other hand, Secondary Succession are those communities/areas previously occupied by well-developed communities. Examples of these communities which are considered secondary succession are those areas which were damaged by fire.
.
.
Ecologists have different opinions on the nature of ecological succession. Frederic Clements believe that ecological succession is a directional and orderly change. His concept on ecological succession is commonly referred to as CLASSICAL ECOLOGICAL THEORY. He enumerated the process of ecological succession in several phases:
.
.
.
1. Nudation. Nudation is the development of an area without any life form. Lava flow is one example of nudation. Another example is the exposure of a surface brought about by glacier retreat. Nudation may be caused by topography (lanslide, volcanic actvity), climate (glacier retreat) and biotic factors (anthropogenic activities).
.
.
2. Invasion. Invasion is the successful establishment of species in the bare, nude area. Hence, invasion includes migration (seeds brought by birds or winds), ecesis (seeds grow while adjusting to the prvailing conditions in the area), and aggregation (colonization of the successful offspring and/or new migrants)
.
.
3. Competition. Because species become established and that they begin to grow and reproduce, competition for space, light and nutrients take place. Competition could be intraspecific (between same species) and interspecific (between different species).
.
.
4. Reaction. Reaction basically refers to the reaction of the biotic and abiotic factors with each other. Because living organisms now inhabit the area, soil, water, light conditions and temperature will change. The environment becomes modified such that the existing community not suited to such changes may be replaced by another community (seral community = intermediate stage in ecological succession advancing towards climax community)
.
.
5. Stabilization. The stabilization point refers to the final community or the climax community.
.
.
What is a CLIMAX community?
A climax community is a community which possesses the following characteristics:
a. the vegetation found in the area is TOLERANT of environmental conditions.
b. the area holds a wide variety of species and a complex food chain.
c. the ecosystem is balanced in terms of:
gross primary production = total respiration
used energy from sunlight = released energy by decomposition
uptake of nutrients from soil = return of nutrient to soil by litterfall
.
d. indivduals are replaced by others of the SAME kind.
.
.
Other ecologists follow the theory that ecological succession is disorderly and unpredictable. This could be referred to as Gleasonian framework. This theory is also followed by Cowles.
.
.
With these contrasting beliefs, let us summarize the different theories explainign ecological succession.
1. Monoclimax or climatic climax theory. This theory is the one developed by Clements. This theory assumes that climax communities are determined by only one (mono) factor, that is CLIMATE.
.
2. Polyclimax theory. This theory was proposed by Tans;ey. It assumes that climax vegetation is influenced not by climate alone but also by soil moisture, soil nutrients, topography, slope exposure, fire and animal activity.
.
3. Climax Pattern theory. While polyclimax theory recognizes other abioitc factors, this climax pattern theory recognizes biotic and abiotic factors to be influential to the climax community.
.
If you are a little bit confused about these contrasting or differing theories, just think of it as "these ecologists are trying to know/establish what will become of a community. All of them believe in the so-called climax community - a relatively STABLE community". But how do we get there? These ecologists explain factors that would define what communities will become in its stable stage.
.
Why does succession happen? Or why do species replace each other?
Three hypotheses are offered in response to this query.
1. Facilitation hypothesis. Later species depends on the conditions created by earlier colonists. The earlier colonists modify the area in such a way that it becomes more favorable to the later species. This modification increases the competetive ability of the later species. The later species can now displace the earlier species. (They may not know they are doing this!)
2. Tolerance hypothesis. Only those species which can tolerate the existing environmental condition can survive. If the later species could tolerate the environemnt better than the earlier species, succession happens.
3. Inhibition hypothesis. This could be opposite of facilitation hypothesis. In inhibition, earlier species may make the are more unsuitable for occupation of later species. (Well, earlier species would always want to resist invasion).
.
.
All these hypotheses/models of succession do not occur solely. We return again to the concepts of conditions and resources and the intricate nature of nature.
.
.
The "story" of succession puts into picture the relationship between biotic and abiotic factors. Abiotic factors define what organisms could thrive in a particular habitat. After some time, these organisms (biotic factors), alter the abiotic factors (temperature, amount of nutrients available, humidity, water). With the altered abiotic factors, other species (later species) may find this new set of abiotic factors favorable... and then because of their existence in the area, may also alter AGAIN the abiotic factors resulting to inhabitation of other species. [Generally: environemnt affects species; species affects the environment]
.
.
.
:)
Subscribe to:
Posts (Atom)