FBS014 COPILATION

1. FOREST ECOLOGY
Compiled by: Edgar D. Castaňares, MiSDS
1. Basic Ecology Principles
2. Forest and Other Ecosystems
3. Hydrologic Cycle
3.1 Evapotranspiration
3.2 Precipitation
3.3 etc.
4. Ground Water
5. Discharge of rivers/streams
6. Forest influences (climate,soil,man,etc.)
Chapter 1
Basic Ecological Principles
The ecosystems is defined as a set of organisms or living-things that interact with their
environment. The set of organisms are recognized as members of their respective
populations. Note that the study of ecosystems is ecology. A population is defined as
an interbreeding group of individuals belonging to a species living together in a locality.
Hence, a group of individuals belonging to various population (i.e. of different species)
living together in a given locality is the biotic community or simply the community. An
ecosystem therefore alternatively may also be defined as a community (group of
organisms living in a locality) interacting with their surrounding environment. Since, the
area of the ecosystem is subjectively set apart by its beholder, the boundary of the
ecosystem as a concept is abstract, for example it can be as small as an aquarium, an
island, a continent or even as large as a thin layer of the earth’s crust that support life,
the biosphere or ecosphere, as also ecosystems. All ecosystems are composed of
biotic (living components) and abiotic (non-living components) that interact.
The biotic components or living components are classified according to the way they
acquire energy or food such as the following: (1) producers (autotroph from Greek auto
(self) and troph (feeding) is the jargon that include all organisms that are capable of
making their own food, thus the term phototrophs are autotrophic organisms (mainly
unicellular or multicellular green plants) capable of photosynthesis, the process of fixing
light energy to convert water and carbon dioxide into food, autotroph includes also all
chemotrophs mainly single-celled organisms that use salts to avail energy to produce
food through a process called chemosynthesis,(2) consumers (phagotroph is the
jargon for heterotroph or organisms that eat others by swallowing food through the
mouth then through the alimentary canal; also, animal parasites absorbing food in their
hosts’ intestines or liver are also here included, herbivore refers to plant eating

2. consumers, carnivore refers to meat-eating consumers, Omnivore refers to organism
that eat both animals and plant); and (3) decomposers (saprotroph is the jargon for
heterotroph that eat by biodegradation of dead animals and plants; because most of the
following are one-celled organisms, actinomycetes, bacteria, fungi, are referred to as
microdecomposer ; on the other hand, multicellular animals like earthworms, soil
insects, worms, etc. are referred to as macrodecomposers).
The abiotic components or non-living components are physical factors are variables
that impinge on the living components of the ecosystem and may be classified
accordingly as;
1. Inorganic substances (for example simple chemical compounds such as waters,
various inorganic salts like ammonium, nitrate, potassium nitrate, ammonia and various
inorganic acids like sulphuric acid);
2. Organic substances (for example complex carbon–compounds like cellulose,
humus, nucleic acid, enzymes amino acids, vitamins, etc.); and,
3. Climate (for example light (jargon is solar radiation), ambient temperature, humidity,
wind velocity, soil moisture, soil temperature, etc.).
Another term for non-living components that affect an organisms, a population and a
given community is the physical environment. The term environment is a much
broader term that encompasses the physical, biological and social environments
together and its use it relatively taken as to whether or not it impinges on an organisms,
a population or a community. It is important to note that the “community interacting with
its environment” is equivalent to the ecosystem concept.
There are properties common to all ecosystem like the following:
1. The use of energy to run functions such as production and decomposition,
2. The circular movement of nutrients or simply “nutrient cycling”,
3. The pattern of biodiversity which is the system’s attribute in terms of species habitat
and genetic diversities,
4. The capability to self-regulation in attaining system equilibrium, or simply
“homeostasis”,
5. The ability of the system to resist external stress or simply “stability”, and
6. The persistence of the system to functions through time or simply “sustainability”.
Finally as basic ecological principle, one should distinguish two diametrically
opposed kind of ecosystem, the natural (i.e. ecosystem as pure outcomes of evolution
and co-evolution) and the artificial (i.e. ecosystem that are outcomes of human doing,
or ecosystems that are cultural in its development and maintenance).

3. Principle I Natural and Artificial Ecosystem (WHAT ARE THEY AND WHAT ARE THEY
NOT!)
Natural ecosystem is any area in the planet earth that is relatively undisturbed by
human beings (=man, Homo sapiens), defined as a product of evolution and co-
evolution and therefore has a unique assemblage of indigenous and endemic biota that
are characteristics to the biogeography if of the surrounding region. Indigenous people
distinguish natural forest ecosystems from artificial ecosystems by using terms like
bakir (Ilokano), gubat (tagalog) lasang (Visayan) woods (English) wald (German), etc. to
represent natural entities dominated by trees.
This Natural ecosystem is mutually exclusive to the Artificial ecosystem concept,
the latter is defined as any area converted by man at the expense of the natural
ecosystem to pave way for man’s.
1. Settlements, e.g. village, town, city, etc.
2. Agroecosystem, e.g. agriculture of various kinds and these could be monoculture or
polyculture, annual crops, perennial crops, (e.g note that forester’s industrial tree
plantations are included here!), livestock/pastures, or a combination of the
aforementioned),
3. Built-up areas (e.g. airport roads, railroads, harbor/pier, science parks, etc.),
4. Mining areas, e.g. gaping post-miming excavations including their artificial re-
vegetation, and
5. Areas untouched by humans but destroyed through indirect impacts of man’s
activities, e.g. destruction of aquatic ecosystems due to poisoning from pollution, forest
fire set accidentally by cigarette butts, exotic plant species and are on the process of
pushing some of them to extinction.
If the natural ecosystem’s final outcome is defined by climate soil, topography,
indigenous/endemic biota (=native flora and fauna), evolution, coevolution, etc., the
artificial ecosystem’s final outcome is defined by man’s culture which in turn is a
function of many anthropocentric (man-centered) factors.
Let us assign natural ecosystem the symbol P and the artificial ecosystem the symbol Q
and they occupy a given finite landscape (numerically denoted as 1), or “the finite land”.
This relationship can be written as equation P + Q = 1. A Philippines without humans
was true earlier than 50,000 years before present and for all landscape in the
Philippines the value of Q is zero, or since Q=0, therefore P + 0 is P=1. When humans
first set foot in the Philippines, small farms appeared thus Q > 0. Hence, the P + Q = 1
is for the first time satisfied, the ratio P/Q ratio is therefore defined. Since Q increases
with human population increase, the ratio P/Q also corresponding declines. When
values of P and Q are equal, P/Q ratio = 1, for example in 1945 the natural forest
ecosystem of the ecosystem of the Philippines was about 15 million hectares while the

4. human dominated ecosystem were about the same area as the natural ecosystems. In
short, 15 million hectares natural forest over 15 million hectares man made ecosystems,
then in 1945 the P/Q=1. Now, the P/Q ratio is less than 1 (the GTZ National forest
Inventory showed the results in late 1980’s). The Industrial tree plantation although
it’s not wrong (from the point of view of economics and pragmatic solution to poverty!)
can irreversibly decrease the P/Q ratio because tree plantations are mainly composed
of exotic tree species (e.g. Moluccan sau, Hawaiian giant ipil-ipil, Eucalyptus spp,
Gmelina arborea, Teak, Mahogany, etc.).
A landscape ecosystem is natural when from coastal to the summit of mountain
there exist an uninterrupted continuum of natural ecosystem (e.g. coral reefs, sea grass
bed, river, Lake Pond, streams mangrove forest, beach forest, mixed dipterocarp forest,
molave forest, oak laurel-conifer forest, mossy forest, alphine forest). This natural
landscape may be also described mathematically as.
P = 1, P/Q is undefined under this situation because Q = 0
On the other hand, a landscape ecosystem which is partly converted by humans
into Q artificial ecosystem at the original P natural ecosystem, then this event
mathematically satisfies, P + Q = 1 and the ratio P/Q is defined or has mathematical
sense because Q is no longer zero!
Principle 2. Whether or not an ecosystem is natural, there are common laws that govern
them in order to function.
2.1. Principles pertaining to Energy
The first law of thermodynamics is “energy cannot be created nor destroyed, but can be
transformed from one form to another.” Applying this law on ecosystems requires some
definitions, Gross primary production (GPP) is the total photosynthate or food produced
by producers independent of producer respiration. Producer respiration refers to the
fraction of the total produced that is used by plants for maintenance independent of
plant biomass production. Because this energy is not used for biomass production, the
energy is simply pumped out from the plant to represent waste. Now, here is the
equation that applies the first law.
Gross Primary Production (GPP) = Net Primary Production (NPP) + Plant
Respiration
For example if GPP is 100, then the sum of NPP =80 and Plant Respiration =20 must
be 100, hence no energy was lost during transformation.
If the GPP is 100 percent of glucose produced by photosynthesis, no energy is lost
during its transformation and used because the sum of the Net primary production and
producer respiration totals 100 percent also. Because everything is accounted and no
energy lost, this law is also called the “law of conservation of energy and matter.”

5. The second law of thermodynamics states that in every transformation of energy there
is always waste, and another way of saying the same is that “there is no 100%
conversion of energy because of ever presence of waste.” By rearranging the formula
above, this law is demonstrated by
Net Primary Production = Gross Primary Production – Plant Respiration (Rs)
NPP (80) = GPP (100) – Rs (20)
Applying the second law of thermodynamics, the Output NPP is equal to the Input GPP
less the waste Rs. It is important to note that this law guarantees the fact that the Input
is always larger than the Output and the size of the Output depends upon the size of
Waste. Large Waste begets small Output and conversely Small Waste begets large
Output.
Systems vary as to the size of waste with respect to input and output. Efficient systems
have high output conversion from input because there is very little waste, the converse
is true for inefficient system. Ecosystem are sometime evaluated in terms of efficiency
by the formula
Since, the general formula for the system efficiency is
Output/Input x 100 = system efficiency
Therefore, its application to ecosystem evaluated is represented by the formula
NPP/GPP x 100 = Ecosystem Production Efficiency %
The Net Primary Production represents the energy that is available for transfer to
consumers via herbivory and to decomposers via litter/mortality.
Food chain is the eat and be eaten process involved in the transfer of energy in the
ecosystem. There are two kinds of food chain depending upon where the food transfer
originate. If its originates from standing plant biomass, the food chain is called grazing
food chain because energy transfer is initiated by herbivores, herbivores in turn are
eaten by carnivores and omnivores, and this eat-be-eaten process continues up to the
top consumer (also called terminal or nth consumer). If It is originates from deposited
litter composed dead animal and plant residues ( jargon of litter is detritus) and then
energy is first availed by micro consumers, in turn eaten by macro consumers up to top
consumer, the food chain called detritus food chain.
In reality, the food are energy transfer In most ecosystems is by no means linear eat-
and-be-eaten process but instead it is describe as a complex interlocking eat and be
eaten process known as food web.
An inventory of biomass of the living components of the ecosystem would normally
place the producers at the base because they have biggest share of community energy
in terms of biomass. The green plants earn the position as the first trophic level (trophic
is Greek meaning “nourishment”). Succeeding trophic levels decrease in size because
of the second law of thermodynamics. Feeding from the trophic level is not 100%
converted because of respiration. Therefore, biomass at the next trophic level is always
less than the previous trophic level. A complete accounting of biomass at various

6. trophic levels from the primary producer at the base to top consumer at the apex would
configure pyramid-like structure. This is called the ecological pyramid based on
biomass.
Related to the ecological concept is the principle of biological magnification of non-
biodegradable contaminants like DDT and toxic heavy metals. When this are
assimilated at the producer level (the base!), the succeeding trophic level such as
among herbivores will have greater concentration percent-wise of biomass than
concentrations in preceding trophic level (plant biomass). Following this trend, the top
consumer suffers the heaviest concentration of decontaminant at geometric rate.
Humans are considered at the top of the food chain, the same with other top carnivores
and so pollution of natural ecosystems is seriously considered by policy makers in
crafting decisions regarding natural resources management.
2,2. Principles Pertaining to Biogeochemical Cycles
Materials are two kinds, the non- essential and essential materials. The essential
materials are objects of interest in ecology because of the nutrients needed by living
organisms. These essential materials or nutrients are classified according to the
quantity they are taking in for metabolic and physiological processes. Macronutrients if
taken in large amount, micronutrients if in small or even trace quantities. The
macronutrients are Calcium, Carbon, Hydrogen, Iron, Magnesium, Oxygen, Nitrogen,
Phosphorous, Potassium, and Iron. Micronutrients are Boron, Cobalt, Zinc, Manganese,
Iodine, etc. Their sources and delivery systems to target living system are of importance
in Ecology.
Ecologists divide the Biogeographic Cycle (BC) into two, (1) the Reservoir Pool (2) the
cycling or Exchangeable Pool. The Reservoir Pool is that large slow-moving
biologically inert portion of the BC, while Cycling Pool is that small fast-moving and
biologically active portion of the BC.
The Reservoir pool is composed of two components, (1) the Gaseous Compartment,
the source gaseous macronutrients, (2) the Sedimentary Compartment, the source of
all nutrients derived from minerals bound in the earth’s crust and hence must first
mineralized to be freed into the hydro-logic cycle for delivery and distribution to living
components of ecosystems.
2.2.1. Gaseous Compartment Based Nutrient Cycles
Hydro-logic Cycle
There is reason why the hydrologic cycle should be first presented. Water is known as
the universal solvent, thanks for its property to dissociate into positive hydronium, H+
and negative hydroxyl, OH. Positive ions of nutrients are absorbed to the positively
hydronium hydroxyl, while negative ion of nutrients absorbed to the positively charged
hydronium water ion. This makes water is highly efficient solvent of both negatively and

7. positively charge materials and therefore are transported at certain segments of the
hydrologic cycle.
The sun is what drives water to be evaporated from surfaces and bodies of water. The
vapor rises and cools adiabatically to condense into clouds, Condensation ends up in
precipitation. Precipitation delivers water as rain hence drenching surfaces wet known
interception (crown of tress, stems and exposed rocks). At the water shed level, the
quantity interception constitutes delivered water on all surfaces that becomes wet after
a rain event and after this immediately evaporates back to the atmosphere. Fraction of
rain apart from interception would then slide down to surfaces of stems as stemflow.
Throughfall refers to rain unimpeded by canopy and therefore delivered directly to the
soil. Throughfall and stemflow combine to account the water that goes to surface runoff,
to soil water saturation and, by process such as infiltration, percolation and seepage, to
basal flow at groundwater. The converging of surface runoff and basal flow gives value
to streamflow output, sometimes colloquially known as drainage output in streams. The
various tributaries in a big watershed all channel to one exit point usually a big river that
delivers freshwater to meet salt water in estuaries and then to open sea. Evaporation
from the sea and all intercepted precipitation inland would complete the hydrologic cycle
are expected to be genotypically different from one another and this should explain their
varied appearances as expressed phenotypes. Sexually reproducing populations have
genetic variation and structural differentiation could be possible. However if the
population is asexually reproducing, for example members (sometimes referred to as
clones) emerge from agamospermy (bearing seeds without the usual preceding
exchange of gametes), then the members should be projecting the same phenotypic
expression from the same genotype all members share.
Whether animal, microbe or plant, all population should have their respective favorite
places, or habitats, where they are nourished, propagated, interact with other
organisms, disperse and recruited. They are also genetically predispose to play more
less specific functions in the community, or in other words each population has a niche
to play in their habitats. Alternatively, the habitat concept is likened to the address of the
organisms in the community while the niche concept is the profession or functional role
that the organism is genetically programmed to play.
Populations are said to be regulated and prevented from reproducing too many
members. One kind of regulation is called density-dependent population regulation. It
portrays a population that is allowed to reproduce in a finite place until overcrowding
reaches a point when intraspecific competition presents extreme scarcity per capita and
thus effecting heavy mortality. The few that survives again grow to start another cycle.
Another kind of regulation is called density-independent population regulation. Mortality
of the population is affected as a result of random catastrophic events (like for example,
accidents, fires and lightning strikes).

8. The number of members in a population at any given time and place is function of four
variables, namely natality, mortality, immigration and emigration. Giving plus number
are natality (birth rate) and immigration (new arrivals from outside) but giving minus
effects is mortality (death rate) and emigration (members leave the habitat never to
return). If pluses are greater than minuses, then the population number N increase.
Conversely, the population number N declines if the reverse is true. The rate of
population decline or increase is determined by the population constant, r (also known
as the instantaneous rate of increase) which reflect the difference between pluses and
minuses, like for example
r (instantaneous rate of increase) = (death + immigration) – (mortality +
emigration)
If the value of r is positive, it predicts how much the present population size will grow at
some future time. If the value of r is negative, the reverse is true. If the value of r is 0,
then the population is constant through time. At any given time in reality, both
population regulations (density-dependent and density-independent) give their
respective influence in the outcome of population dynamics. Such combined population
regulations manifest the so-called rate of rarefaction, m and N𝒆 is the equilibrium
population size.
The equilibrium population size varies as functions of space, given that across a
landscape the set of space differ in terms of physical variables, such as light,
temperature, quality and quantity of nutrients, soil moisture, wind speed and
presence/absence of biotic factors like the presence of pollinators, dispersal agents,
predators and parasites.
Population ecology also discusses how different population interact with each other
through the following: protocooperation, mutualism, competition, predation, parasitism,
commensalism, ammensalism, and neutralism. Protocooperation is invoked when
population A and B mutually benefits each other but the relationship is not obligatory.
Mutualism is like protocooperation except that the relationship is obligatory. Competition
between population A and B happens because they have common resource that are
scarce in supply so that one negatively inhibits the other and vice versa. Predation
population A the predator and population B its prey and this relationship could endure
(without danger of extinction for each other side) if there is perfect density population
regulation on both populations. In parasitism, unlike in predation that kills its prey, the
parasite Population A inhibits its host Population B but the host is not killed.
2.4 Principles Pertaining to Limiting factors and the Niche Concept
Response of population to environmental gradients or variables is believed to be
controlled by so-called PRINCIPLES OF LIMITING FACTORS. The one that proposed
by Liebig is the Law of the Minimum and the one proposed by Shelford is the Law of
Tolerance.

9. The Law of the Minimum states that given all nutrients are adequate in supply, the one
factor in short supply is the limiting factor. The Law of Tolerance is considered more
complete because the limiting factor is not only the one with least supply but also those
factors that are abnormally in excessive supply. Between the maximum and minimum
threshold limits is the tolerance range of an organismto a factor. Thus, a species or its
population can be excluded if, in the area recruitment, there are factors there that are
outside the tolerance range of the members of population.
The genotypes of the population members control the tolerance ranges of member
organisms. This means such tolerance ranges are inherited and transmitted to
progenies. The multidimensional tolerance to all environmental factors combined
together dictates what Hutchinson calls as the set of n- dimentional factors of tolerance
ranges that defines theoritical living space of a population or, in short, the fundamental
niche of the population. However, this living space is seldom fully exploited by members
of the population because of interspecific interactions, like for example competition,
predation, parasitism, and pathogenesis. The magnitude of pressure by such
interspecific interaction causes the population to occupy and exploit only a fraction of
the theoretical fundamental niche. This actual portion of the fundamental niche realized
by the given population is what Lewins call the realized niche of the population. The
realize niche could expand or contract. If the environmental pressure relaxes, then the
realized niche would expand approaching fulfillment of the fundamental niche. The
reverse is true when environmental pressure further intensify. If the pressure continuous
to intensify beyond minimum and /or maximum limits, said population is being pushed to
the edge of imminent extirpation.
Populations are not easily brought to extirpation nor its species pushed to utter
extinction. This is because populations have the power to disperse and move to places
so that they could occupy places that match their fundamental richness. There is also
another way out to escape extirpation or extinction. This way out is basic in ecology and
known as factor compensation.
Factor compensation is defined as the development of structures by the population in
order to circumvent the adverse impact of limiting factors. If the pressure of limiting
factor is very gradual, then the organism in its lifetime can acclimatize and develop
defense against limiting factors. This ability to develop defense with gradual exposure to
limiting factors is Climate is determined across latitudes by solar angle and path length,
hence the tropics is warm around the equator, then at higher latitudes next to the tropical as the
temperate zone, then finally the very cold arctic. Seasonal variation in all latitudes is due to the
change of the earth’s axis at it orbit the sun
Atmosphere circulation is caused by the solar radiation that creates air pressure gradients that
is very low in the equatorial region causing the so-called intertropical convergent zone (ITCZ).
Hence, one convection cell is associated with the ITCZ for north and south of equator. The
converging winds are called monsoons. They bring high rainfall when they pass big bodies of
water (oceanic or maritime monsoon). And little rainfall when they pass large masses of land
(continental monsoon). Also, if in the presence of high mountain ranges that trends north-

10. south, seaward slopes would receive higher precipitation due to the so-called orographic effect
(also rain shadow effect). The leeward zone of the same mountain range receives little rain
and has corresponding very seasonal climate regimes.
Thus, globally the tropical areas that enjoy evenly distributed rainfall (perhumid climate) develop
tropical rainforests. This kind of forest exhibits complex tiering with five recognized strata such
as emergent layer, understory layer, shrub layer, and herbaceous ground layer. It is very high in
specific diversity.
In higher latitudes next to perhumid climate are areas with humid but very seasonal climates.
Forest type here is the tropical deciduous forest usually in areas with rugged mountains and
rainshadow effects and also at latitudes approximately 20 degree north or south. Stratification is
similar to TRF but during the dry season tree shed their lives. Above this latitude would be area
with very long dry season and grassland become dominant while trees are few and scattered.
This biome is called savanna and is famous in Africa for great herds of elephant, buffaloes,
impala, giraffe, big cats like lion, leopards and cheetah, hyaena, and wild dogs. Between the
savanna and desert at 30 degrees N to S latitude in is a tropical grassland that merges
gradually with the desert. Then again 40degree N and S latitude in continental areas that
receive low rainfall, the natural grassland occur and known with several names like prairie in
north America and steppe in central Asia. However, in the same latitude in maritime areas such
as seacost, the temperate deciduous forest dominate the landscape. Higher latitudes then the
temperate coniferous forest replace gradually the broadleaved temperate deciduous forest.
Finally at sixty degree and higher across the tree line, is a treeless biomes known as tundra
where reindeer and polar bear live.
The gradient from lowland to mountain summit resembles vegetation transitions that roughly
reflect latitudinal gradient in all tropics at coastal areas particularly in the estuary (meeting of
fresh water and marine) at tidal mudflats develop the mangrove. The forest is inundated by
brackish water during high tide and exposes its muddy forest floor during low tide. At the back of
the upper tidal line is the strand vegetation known as beach forest. Here, characteristics stands
tree like barringtonia asiatica and Casuarina equisetifolia are dominant and abruptly merge
seaward with mangroves like Rhizophara trees, avincennia spp. And sonneratia spp. From the
beach forest to about 1000m asl., the lowland mixed dipterocarp forest predominate. Above this
zone is a forest dominated by oaks, laurels and conifers. In the cordillera, Zambales and
mountains of Mindoro, fire prone highlands are covered with pine forest represented by pinus
kesiya and P. merkusii a 200m asl, the health forest replaces the montane oak-laurel-conifer
forest and the trunks of trees are covered with moss. This gnarled open canopied dwarf
community of trees is the mossy forest and may be composed by species of the family
Ericaceae e.g. rhododendron and vaccinium spp.