BLOG 10-Habitat Fragmentation

As defined, habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat). It is also the process by which isolated patches of habitat are created through land clearing and deforestation. In this mechanism, a type of habitat is lost often caused by road development, which confines wildlife populations to small, isolated patches of their original habitat.

Fig. 1. The Developed Memorial Garden

An example of habitat fragmentation is the development that happened near a neighbouring space at the back of our house. This area, about 5-8 hectares used to be a residential area with a diversity of plants around plus the growing of some poultry animals. Looking back, when we would go up to our room, we would peep through our windows and happily would observe the wide area. We used to see tall trees and other unfamiliar plants that abound the area not to mention the noise that we could hear from a variety of animals that made this place their niche. I remember, my family would comment that they could not sleep due to a lot of animal sounds that they hear vibrating around the area. But this was already five years ago. Now, this area became the Heaven’s Garden, a famous memorial park.

I remember, when the area was being developed, I observed some unusual things. For the many years we have been staying in our residence, it was the first time that about 2 – 3 snakes were found inside our house! Not only this, but we also saw a lot of rats in the four corners of the house. It was always a frightening experience for all of us when we would see the tail part of the snake hiding under one of our cabinets! How we wish we would be able to immediately kill them! Everybody was so afraid to go down or go to the kitchen because of this. Of course, the last resort is to kill the animal and there was always a feeling of relief when this happened. This happened at least 3 times in a month. It was so ridiculous that after we were able to kill all the snakes, the rats came next. These were really pests that we always wanted to get rid of them. At one point, I realized that the proliferation of snakes and rats in our place had something to do with the development of Heaven’s Garden. Truly, the transformation of the area caused the destruction of the animal and plant habitats that thrive there. Rats and snakes immediately transferred to our place as their new habitat. Since their original habitat was already destroyed, the animals found a newly-isolated space in our house so that a new population of their species may be formed again. But of course, this would not be possible since our place is not the habitat for these animals. I recall, when the bulldozer was being used to clear the area, there was also noise pollution that could somehow disturb and destruct the habitat of the diverse groups of organisms there. It was really a chaos in the area making the animals cross-over to land at our place!

Fig. 2. The Facade of Heaven's Garden Memorial Park

         Another habitat fragmentation I observe is the development of the road along Calamba connecting to Lipa City. For many years, the place was not being touched but due to the increasing population that causes heavy traffic along this area, this development was pushed through. I remember, when we drive from Manila I always see many plants in the area and even if I do not see the animals there, I know a lot really live there. However, now that the area has already been transformed, the animals on one side of the road might now be blocked from moving to areas on the other side. The developed road is the barrier that blocks the movement of the animals from one side to the other side. 

Blog 9 - Ecological Succession

Ecological Succession refers to the process of orderly changes in the composition (which may be biological, physical, and chemical) or species structure of an ecological community over time. It describes the development of an ecological community through a series of stages that are interdependent with each other; in addition, each stage prepares itself for the next. These stages are the pioneer, moss, grass/prairie, shrub, tree and climax stages. The several types of succession varies by disturbance/human interference, fluctuating species interactions/recurring events, soil changes caused by organisms, soil changes caused by external environmental influences, and many others. Such types of succession are primary, secondary, cyclic, autogenic and allogenic.

Ecological succession is understood as a fundamental concept in ecology and categorized as a habitat terminology. It shows the growth and development [and possibly destruction and re-establishment] of an ecosystem with recognition to the biotic components, i.e. lichens and mosses, that shape the abiotic components, i.e. rock surfaces, and elevate the ecological community to the next stage. It helps explain the abundance and distribution of biodiversity (which increases as much as a tenfold until climax stage) in the environment. Since ecological succession can also explain how some species can become less or more abundant in a community at a certain interval, it explains the distribution and abundance of organisms, which is one idea that ecologists seek to explain.

            Succession may initiate due to natural disaster/disturbance that destroy the existing community, i.e. forest fires and severe wind throws, or by the formation of an unoccupied habitat, i.e. a cooled lava flow and glacial tills. If the area develops initially without human interference, the first stage in ecological succession would be primary succession, which is the so-called Pioneer stage that is characterized by lichens, algae, and fungi that facilitate paedogenesis, or the formation of soil, which is vital to vegetation. This pioneer stage prepares the habitat for the moss stage, which prepares the forest area/rock surface with vegetation. Soon after, insects start to appear.

            If the land had been previously modified by man, which means the soil has already been conditioned with higher nutrient content, or the land was an already established ecosystem reduced by natural events, secondary succession happens instead. Secondary succession occurs on preexisting soil, as opposed to primary succession. It needs not pioneer colonial species (lichens, algae, or fungi) and may still contain vegetative organs of plants to help start developing an area with vegetation; thus, it is faster than primary succession.

With regard to primary succession, the organic matter will gradually accumulate (in this stage) and support the growth of more complex plants that live in thin, mineral-based soil, with such plants being grasses and some shrubs. This stage is the grass/prairie stage. It brings about more animal types ranging from insects to organisms that eat insects such as bird insectivores. Then more complex plants like shrubs grow, this is the shrub stage. Some of these plants produce seeds that scatter around and more and more nutrients accumulate in the soil throughout time. Until more complex shrubs and trees grow, it still has yet to reach the Climax stage.

The climax stage or climax vegetation is characterized by type of vegetation best suited (soil type, precipitation levels, moisture, nutrient availability, or temperature.) At this stage, the ecological community should reach stability (which is measured by the Photosynthesis Respiration ratio or PR ratio, and it should be equal to one) and there should also be no more net accumulation of organic matter. Trees will grow and eventually limit the sunlight available to the species below it; eventually, the dark-tolerant plants will remain and there will be a reduction or increase in the abundance of other species in the climax forest, until the species that can grow most efficient and produce the most viable offspring will become the most abundant organisms.

Changes in microclimatic conditions (like wind patterns, shade, or evaporation from soil) and available resources can change the biotic structure by fluctuation or abundance.  Here we see how abiotic factors can affect biotic components. Trees, for example are known to frequently moderate the microclimate below them. The more there are trees that block sunlight, the less the chance of extreme temperature fluctuations, which is good for animals that tolerate less extreme temperature and moisture, i.e. insects living under a log. If this microclimatic condition is disturbed, it may result to the disappearance of the animal species it helps regulate. When these animal species disappear, it possibly causes a disturbance, this time, in the microclimatic conditions. The animal species that begin to disappear also disappears along with its contribution to the abiotic components/microclimatic conditions it controls.

MECHANISMS OF SUCCESSION

The general process of ecological succession starts with Nudation, which is the development of a bare site without any life form. The three types of causes of nudation are topographic, climatic, or biotic. It is topographic if it is due to soil erosion by gravity, wind or water, with examples of these being soil erosion, landslide, and earthquakes. The cause of nudation is climatic when dry periods, glaciers, storm and hail and the like destroy the previously existing community. It is biotic when human activity is involved and man is responsible for the destruction; also, epidemics caused by bacteria, etc destroy the whole population. Whatever the cause of nudation, soon after, a new surface in the area will be exposed.

            The mechanism that follows nudation is Invasion, the successful establishment of species in a bare area. Invasion usually happens in three steps, namely: migration, ecesis, and aggregation. Migration happens when various migration agents like water and wind make seeds, spores, and/or other propagules of species reach and disperse the bare site. Ecesis, the process of successful establishment of a plant or animal species in a habitat, is the following step after the propagules or seeds successfully adjust with the prevailing condition of the bare site. Colonization may also follow ecesis; it is also the initial growth of the vegetation, or when the seeds or propagules begin to grow a start to reproduce. In Aggregation, the established organisms in the bare area increase in number due to colonization by successive offspring and new migrants. Those plants first to colonize are called pioneers.

            The next mechanism is Competition and Coaction. As the aggregation of the number of individuals increases, competition arises as a result of natural resistance like the need for the acquisition of nutrition, light and the limited space. The said competition can either be interspecific or intraspecific. The two differ in terms of the species involved. Interspecific competition involves different species competing for the same source, while intraspecific competition involves organisms belonging to the same species competing for the same source. Coaction on the other hand is defined as ‘any of the reciprocal actions or effects, such as symbiosis, that can occur in a community’ or simply any interaction or relationship among organisms within a community. Examples of coaction in an ecological community are amensalism, commensalism, parasitism, mutualism, among others.

            Following competition and coaction is the mechanism of Reaction. This significant stage involves the modification of the environment by the influence of the living organisms in the existing community. The modification discussed are changes that take place in abiotic factors such as soil, water, light conditions, temperature, etc. As the environment changes, it becomes unsuitable for the existing community and so sooner or later it will be replaced by another community, or seral community. Here one might be able to observe the existence of seral stages or developmental stages, which involve seres, a sequence of communities which replaces one another in the given area. These seres are made up of different seral communities.

            The last mechanism in succession is Stabilization. This is the climax community or final terminal community. Coming from the name itself, the community becomes stabilized and sustains itself in equilibrium with the climate of the area. The climax community becomes established for a longer period of time and can maintain itself in harmony with the climatic conditions. The stage is called Climax stage.

Ecological succession has never appeared to me completely (with myself being able to witness all the stages and mechanisms in one area), but only gradually and by stage. I used to observe ecological succession in abandoned plots or farming areas nearby my parents’ ancestral house in La Union. The area being highly urbanized, it would be quite rare to still see land allotted for farming. In our area, there are lands that have been left uncultivated and some previously cultivated. I also noticed the abandoned land areas that only had soil with little vegetation. Here I observed the grass stage developing into the shrub stage. Only a few trees were able to grow in the meadow-like field across our old house, which was, observably, in the shrub stage. My observations follow a time span of around 15 years. The lands had observable yet few changes every year.

As we moved to Los Banos, I am finally able to observe a climax stage and a climax forest. I noticed the sudden abundance and diversity of plants and animals (especially insects) when I went hiking once to Peak 3 at Mt. Makiling, UPLB. I also noticed the plant diversity on the different hills as we drove along PCCARD road. Different populations (such as coconut trees) aggregate in one area and become observable to the naked eye even from afar.

I also observed the climax stage in my trip to Palawan last May 2010. I could easily compare the great diversity in flora and fauna along the mountains near Cleopatra’s Needle (the highest mountain there) and near St. Peter’s mountain (in which the underground river is found) to the agriculturally-developed mountains found in Bay. The mountains near here in Bay were probably in the “young forest” stage or somewhere still near shrub stage. The areas on the mountain are still not fully occupied, unlike the forest area on Cleopatra’s needle where every square meter of the land was occupied by vegetation or forest area. Knowing this, there was interspecific competition between the different plant species for sunlight and animal species for food.

Fig. 1. Mouth of the Cave

I was able to characterize most of the stages I have seen with the amount of vegetation I observed and animal species that are likely to be present.

BLOG 8 - ENERGETICS AND MATERIAL FLOW

Energetics is the study of the transformation of energy. It encompasses thermodynamics, chemistry, biological energetics, biochemistry and ecological energetics. It also describes the useful and non-useful tendencies of energy flows and storages under transformation.

The origin of Energetics still remains unknown today, with different theories:

·         found in the work of the ancient Greeks

·         mathematical formalization began with the work of Leibniz 

·     Rankine formulated the Science of Energetics in his paper Outlines of the Science of Energetics published in the Proceedings of the Philosophical Society of Glasgow in 1855

·        atomic view of the atom forwarded by Boltzmann's  gas theory

·        Lotka proposed that the selective principle of evolution was one which favoured the maximum useful energy flow transformation, which influenced the development of ecological energy

Liet.-Col. Richard de Villamil (1928) said that W. Ostwald and E. Mach subsequently developed the study and in the late 1800s energetics was understood to be incompatible with the. Proof of the atom settled the dispute but not without significant damage. In the 1920s Lotka then attempted to build on.This view subsequently influenced the further development of ecological energetics, especially the work of Howard T. Odum. 

De Villamil contrived a system that divides mechanics into two branches: energetics (the science of energy) and "pure", "abstract" or "rigid" dynamics (the science of momentum ). The dimensions for dynamics are space, time and mass, and for energetics, length, time and mass.

Thermodynamics is the movement of energy. It is defined by laws which serve as the basis for many biological concepts. These laws dictate how energy can be transported, which of course can be applied to ecology because energy transfer is what drives metabolism and, on a larger scale, food chains and food webs.

The principles of energetics are as follows:

• Zeroth principle of energetics

If systems A and B are in thermal balance, and B and C are also in thermal balance, then A and C are in thermal equilibrium balance.

• First principle of energetics

increase in the internal energy = energy added to system by heating- amount lost in form of work

• Second principle of energetics

Any isolated thermodynamic system tends to increase the total entropy over time, reaching a maximum value.

• Third principle of energetics

all processes cease and the entropy of the system approaches a minimum value if the system reaches absolute zero of temperature

• Fourth principle of energetics

Two opinions:

• Onsager reciprocal relations - as the fourth law of thermodynamics, it would constitute the fourth principle of energetics.
• H.T. Odum’s Maximum power- Odum proposed the Maximum empower  principle as a corollary of the maximum power principle.
• Fifth principle of energetics

Hierarchically increasing is the energy quality factor. Hierarchical webs develop flows of energy and maximize the power of the system

• Sixth principle of energetics

The energy/mass ratio measures the material cycles that has hierarchical patterns and determines its zone and pulse frequency in the energy hierarchy

Energy is applied to ecology through its entry and release in the ecosystem. Some energy is lost as heat re-enters the system to maximize the energy use. Plants (producers), animals (consumers), detritivores and other organisms depend on the energy transferred or transformed from one trophic level to another. Energy transfer is what drives metabolism and, sometimes food chains and food webs.

Energy enters the ecosystem through photosynthesis, which transforms solar energy into chemical energy transformed and stored by plants (primary production). The energy is then transferred to herbivores (secondary production). The activities and processes done by the consumer consume the energy and others are lost in the form of heat. The next trophic levels stay the same, until the decomposers feed on the energy left. The heat energy that is lost then re-enters the ecosystem.

An Ecological Pyramid (or Trophic pyramid) is a graphical representation designed to show the relationship between energy and trophic levels of a given ecosystem. Most commonly, this relationship is demonstrated through the number of individuals at a given trophic level, the amount of biomass at a given trophic level, or the amount of energy at a given trophic level. It is worth noting that all Ecological Pyramids begin with producers on the bottom and proceed through the various trophic levels, the highest of which is on top. (Above is an image of an Ecological Pyramid).

There are two types of Ecological Pyramids that exist:

­   Pyramid of Biomass shows the relationship between energy and trophic level by quantifying the amount of biomass  present at each trophic level (dry mass per trophic level).

­   Pyramid of Energy shows the direct relationship between energy and trophic level. It measures the number of calories per trophic level. As with the other, this graph begins with producers and ends with a higher trophic level.

A Biogeochemical cycle is an organic cycle is a circulating or repeatable pathway by which either a chemical element or a molecule moves through both biotic (“bio-”) or abiotic ("geo-") compartments of an ecosystem. In effect, an element is chemically recycled, although in some cycles there may be places (called "sinks") where the element accumulates and is held for a long period of time. Important  biogeochemical cycles are Hydrologic cycle (Water Cycle), Carbon cycle, Nitrogen cycle and Phosphorus cycle 

­  

Specific applications of the concepts mentioned above are as follows:

a.     Energetics

- Computations of Calorie Transfer

- Utilization of Plants as Food

b.     Thermodynamics

- Calculations of Energy Transfer in Food Chains/Webs

- Improvement of the Stability of a Community in an Ecosystem

c.     Ecological Pyramids

- Measurement of Biomass in each Trophic Level

d.     Biogeochemical Cycles

- Regulation of the Amount of Needed Chemicals Present in the Environment

WHAT HAVE WE DONE SO FAR?

Exit your house and walk on the road for a bit. Eventually a car will pass by emitting gray gas. This gas is one of the factors that disrupts  the carbon cycle. Accumulations of gases such as these cause one of the world’s biggest problems today, Global Warming.

Think of a filter, with sand passing through it. A small quantity of sand takes only a small time in passing through the filter, while a large quantity, in opposite, takes a long time to pass. Sooner or later the sand would accumulate and the time it takes to filter all the sand will become longer. This is what’s happening to the carbon cycle today, with the atmosphere as the filter and carbon as the sand. When the carbon piles up in the atmosphere, the cycle is disrupted and phenomena like global warming (piling up of gases in the atmosphere causing holes in the ozone which provides way for too much sunlight and heat) results.

Global warming is worsening each day and we can largely feel its effects on us and on the environment. Our climate has changed from stable to unpredictable during the last years. I remember this one conversation I had with my late father when we were taking a stroll in the campus of UPLB (this was the time when I was still a college student in UPLB) I was complaining about how hot the weather was, and that if I did not get into a shade soon I would get sunburns all over my arms and face. To this he replied in a did you know that tone that when he was young, no matter how many hours he stayed outside to play or take a walk he did not feel uncomfortable in any way with the heat. He told me how lucky he was that he been born in his time and not in the recent years where Global warming is coming to extremes. I was amused as to how the world can change so immensely in such a short time period.

I still remember when this experience with my son when he was still studying at Maquiling School Inc. We were coming home from school via a service jeepney one rainy day. Soon the vehicle came to a stop and we realized that we were already in front of our house. With an umbrella ready in hand, my son came out into the rain and walked towards our gate. While opening the gate a drop of rain fell onto his hand and he told me  it felt strangely different against his  skin. He let a few drops fall onto his hands again and decided that something was wrong with the rain, so coming in, he asked me about it.  Being familiar with this phenomenon, I explained to him that what he had felt was acid rain and it was becoming common nowadays. I added that acid rain is the precipitation of a mixture of gases (air pollution) with clouds in the air.

Recently, my son has found out that the principal causes of acid rain are sulfur and nitrogen compounds from human sources, such as electricity generation , factories, and motor vehicles. Through these human sources, the normal amount of nitrogen in the air has doubled, causing a disruption in the nitrogen cycle. The disruption of the nitrogen cycle has contributed to acid rain among the other consequences that come.

He  experienced acid rain again after a few days and after that he didn’t feel or let alone notice it anymore. May be my son had just gotten used to the acid rain or it really had stopped.

I realize also that many anthropogenic activities can affect the operation of the different biogeochemical cycles.  Some of these are the following:

• ·         Trees and Plant Degradation- the simple plant destruction anybody does add up to a big change. Every plant that is not replaced in any way counts. If ever more trees are present, the carbon dioxide present in atmosphere will be minimized
• ·         Burning Fuels- even though this process has temporary benefits to man, it breaks down the nitrogen molecules present in the atmosphere, sustainably breaking the nitrogen cycle within a place.
• ·         Land-use change- This technique used in vegetation may be harmful. This adds up to the carbon dioxide in the atmosphere.
• ·         Fertilizers/ Vegetation plus Soils- This mechanism takes up more carbon needed in the atmosphere. In return, less is given back by this.

BLOG 7 – FOOD WEBS AND FOOD CHAINS

Food web vs. food chain

A food web is a graphical description of feeding relationships among species in an ecological community, that is, of who eats whom. It is also a means of showing how energy and materials flow through a community of species as a result of these feeding relationships. On The other hand, food chain is a succession of organisms in an ecological community that constitutes a continuation of food energy from one organism to another as each consumes a lower member and in turn is preyed upon by a higher member.

                                                           Fig. 1 A Food Web

The trophic-dynamic model of ecosystem structure

In ecology, trophic dynamics is the system of trophic levels, which describes the position that an organism occupies in a food chain: what an organism eats, and what eats the organism, for every level there is an increase in trophic level but a decrease in energy because of the absorption of biomass, thermodynamics and the law of conservation of energy in every trophic level. All trophic systems start with an autotroph that can be either photoautotroph or litoautotroph. All trophic-dynamic systems have four main parts: the abiotic environment, producers, consumers, and decomposers.

                                                  Fig. 2 An Ecological Pyramid

Top-down vs. bottom-up control of trophic levels

Both are theories of control of ecosystems but they have different functions.
Bottom-up control states that an ecosystem’s function is ultimately controlled by the nutrient supply to the primary producers and if the nutrient supply is increased, the resulting increase in production of autotrophs is propagated through the food web and all of the other trophic levels will respond to the increased availability of food (energy and materials will enter the cycle faster). 

Top-down control states that an ecosystem’s function is ultimately controlled by predation and grazing by higher trophic levels on lower trophic levels and if there is an increase in predators, that increase will result in fewer grazers, and that decrease in grazers will result in turn in more primary producers because fewer of them are being eaten by the grazers. Thus the control of population numbers and overall productivity "cascades" from the top levels of the food chain down to the bottom trophic levels.

Relationship between food web/food chains and biogeochemical cycles

            The movement or circulation of biogenetic nutrients through the living and non-living components of the biosphere or of any ecosystem is called biogeochemical cycling. Thus, it involves both biotic and abiotic components of organisms. There are two types of biogeochemical cycles, also called nutrient cycles, first is the closed system wherein nutrients such as oxygen is recycled instead of being lost and replenished constantly and is the complete opposite of the second type, the open system, where all energy comes finitely but within a long-lasting source like the sun but always lost. These two types are important in an ecosystem because they help producers and consumers live. Therefore, are needed for a productive food web/chain.

                                                                Fig. 3 Water Cycle

Applications of food web-food chain concepts

Absorption of Solar Radiation: autotrophs primarily absorb solar radiation.

Energy Transfer: By each trophic level consuming another, energy from the consumed level is transferred to the next. However, energy transfer is not efficient. In fact, only about 10 percent of the energy available at one level is actually passed onto the next. That means a massive level of life is needed at the base in order to sustain the life forms at the highest point. For example, if 100,000 calories are produced by a group of certain plants, only 1,000 calories will be transferred to the consumers that eat them. This is partly because not all plants or animals are consumed at every trophic level, nor are all the parts, such as beaks, shells, certain roots, leaves and poisonous fruits.

Interdependence: This interdependence of the populations within a food chain helps to maintain the balance of plant and animal populations within a community. For example, when there are too many carabaos; there will be insufficient grasses for all of them to eat. Many carabaos will starve and die. Fewer carabaos mean more time for grass and shrubs to grow to maturity and multiply. Fewer carabaos  also mean less food is available for the cow to eat and some carabaos will starve to death. When there are fewer cow, the carabao population will increase.

For example, many shark populations have been heavily overfished by people, further decreasing their predatory effects on otters. 

          In many places still without otters, commercial divers intensively harvest sea urchins for international seafood markets (see slide). Though the harvesting patterns and therefore the community effects of humans and otters may be quite different, to some extent, human harvests may simulate the controlling effect of otters. 

How have humans affected the food chain? 

    When we spray pesticides, we put the food chain in danger.  By breaking one link on the chain means all of the organisms above that link are in threat of extinction (like the domino effect).  By hunting animals nearly to extinction, everything above the animal in the food chain is put in danger.  A 'chain reaction' in the food chain can be perilous!  Since the food chain provides energy that all living things must have in order to survive, it is imperative that we protect it.

 IRRI is an autonomous international institute based in Los Banos, Laguna.  The Philippines is one of the foundation institutions of the CGIAR (Consultative Group on International Agricultural Research), and is dedicated to improving the lives and livelihoods of resource poor rice producers and consumers worldwide. It is a nonprofit organization doing research and training on agriculture.

IRRI has been at the forefront of rice research for almost thirty years (has been in the Philippines since 1960), delivering new rice varieties and practices to rice farmers throughout Asia and the developing world. Together, farmers and consumers find solutions to world hunger.

Through research, IRRI has been able to help almost half of the people all over the world who eat rice. It is doing research to help farmers grow MORE rice by using FEWER resources (less land; less water; less work and less chemicals. When there is more rice, there will be enough food for the 3 billion people who eat rice in the world!

Since 1960, IRRI has been able to grow rice plants and grains that grow faster; grow in different kinds of places; need for fewer chemicals; fight against harmful insects and are strong against plant diseases.

However, the use of pesticides can lead to extinction of some important species. Before learning to drive at the Jamboree route, during traffic, I take the Maahas road in going to UPLB. I remember there was a time when my daughter and I were covering our nose and breathing through our mouth when we passed the area near the railroad crossing. The foul smell? It was because of the smell coming from the pesticide that was previously applied by the IRRI people. Our respiratory system was affected since we would cough and sneeze due to the smell. Even if we did not see the species that have been killed, I knew that they were really affected. I knew that the participants in the food chain, for example, insects, and aquatic organisms (since the area is near a creek) were killed due to the pesticide. And this effect might put the food chain in chaos! If I could only have the authority to stop this application of pesticide, I know the extinction can be prevented. Perhaps, the least that I can do is to write a complaint to the Mayor so that the problem may be addressed properly.