Forest Ecology PDF Refresher Course 2024

Refresher Course for Forestry Graduates 2024 FOREST ECOLOGY By CRUSTY E. TINIO, Ph.D. LERMA SJ. MALDIA, Ph.D....

Refresher Course for Forestry Graduates 2024 FOREST ECOLOGY By CRUSTY E. TINIO, Ph.D. LERMA SJ. MALDIA, Ph.D. ALONA C. LINATOC, Ph.D. Associate Professor(s) College of Forestry and Natural Resources University of the Philippines Los Baños DEFINITION OF TERMS Abundance - the number of individuals in a given population. Acclimation - a reversible physical change in an adapting organism in response to environmental pressures. Acclimatization - adaptation to a different climate. Adaptation - how living things change what they do or what they are to survive in a particular environment. Albedo - the luminosity shining from a reflective surface. Algae (algal) bloom - explosion of a phytoplankton population, sometimes because of incoming pollutants that artificially enrich the waters with nutrients. Allelopathy - a type of chemical plant interaction where one plant exudes a chemical substance that inhibits growth and the development of another plant. Alien species – intentionally or unintentionally introduced organisms in an area; some reproduce, multiply, disperse and spread, competing for food, nutrients, and space as invasive alien species (IAS). Allopatric speciation - when isolation occurs through geographic separation of populations. Alluvium - sediment transported by water, usually river or stream water. Alpha diversity (Local diversity) - the variety of organisms in a given habitat or location. Amensalism – population B the host is unaffected by population A and the latter is inhibited or negatively affected. Anemophilous - seed plants pollinated by the wind. Atmospheric cycles - a large percentage of the nutrients is in the form of atmospheric gas i.e., nitrogen and carbon (mainly carbon dioxide). Autecology - is an approach in ecology that studies the organisms or a single species, population- centered approach. Autogenic - originating from within a system. Autotroph - an organism that produces its own food. Basal area - a forest's tree density expressed in square feet. Page | 1  Refresher Course for Forestry Graduates 2024 Benthic - organisms living on the sea floor. Beta diversity – variety of organisms occupying a number of different habitats over a region; regional diversity Biocoenosis – a term equivalent to the biotic component of an ecosystem. Biogeochemical cycles - the great looping and returns of life-giving substances through the environment. Biological magnification - process by which pesticides and other substances become more concentrated in each link of the food chain. Biomass – weight of living material, usually expressed as dry weight per unit area. Biome - the largest ecological regions distinguishable by characteristic plants and animals. Biotic community - a self-sustaining community of living things; an ecosystem. Biotic factor - the environmental influence exerted naturally by living organisms. Biotic potential - a population's maximum production rate given ideal surroundings and resources. Biotope - an environmentally uniform area; the physical aspect of an ecosystem. Bog - marshy land covered by shrugs and mosses. Carnivore – organisms that eat animals only Carrying capacity – ability of a locality to produce a certain level of possible community standing biomass; the maximum population an ecosystem can support of a given species. Chablis - the formation of gaps in a forest by the fall of a dominant or emergent tree. Chaparral - an evergreen shrub community adapted to dry seasons. Climate - state of atmospheric conditions (AC) on a year-to-year basis in a given location of the earth’s surface; long term pattern of weather Climax - the culminating stage of plant succession in a given ecosystem. Cline - a gradient of variations in a species that stretches across a geographical location. Closed system - one that exchanges energy, but not matter, between itself and its environment, e.g. Earth. Coevolution - interactions between species that impact how both evolve. Colluvium – mixed deposits of soil materials and rock fragments accumulated near the base of steep slopes through soil creep, landslides and local surface runoff. Commensalism – population A the commensal is benefited by living in population B the host, the latter is unaffected. Community – is a set of organisms of various populations living in a locality. Competition – population A and B scramble for common resources, both populations limited. Competitive exclusion - where one species competes another into extinction. Conspecific populations - populations of the same species (subspecies, forma, variety, race, ecotypes, hybrid, cline) Page | 2  Refresher Course for Forestry Graduates 2024 Consumers - are heterotrophs which usually pass food through a mouth, pass intestines, and undigested material is expelled through an anal opening as fecal material. Continental drift theory - the theory that continents are mobile rather than fixed. Continuum - subtle gradations in plant or animal communities within an ecosystem. Corridor – a narrow connection between two patches of suitable habitat. Cycling pool - is the small but rapidly moving portion of the biogeochemical cycle that is biologically active. Decomposers - organisms that utilize dead plant or animal material for food and that release the component elements to the environment, thus contributing to circulation of these elements in the ecosystem. Density - the number of individual plants, plant parts of animals of one or more species of one area; the reciprocal of sample area density is termed mean area. Density dependent factor - factor whose intensity of action is governed by population density. Detritus - decomposing organic matter. Detritivore - an organism that eats detritus. Directional selection - allele frequencies underlying a range of variation tend to shift in a consistent direction in response to directional change in environment. Disclimax - a stable community other than the climate or edaphic climax, which is maintain due to the interference of man of his domestic animals. Disruptive selection - intermediate forms are selected against, extreme forms in the range of variation are favored Distribution - the area occupied by population of a species, i.e. the geographic distribution or range. Dominance – control within a community over environmental conditions influencing associated species by one or several species. Ecesis – denoting initial establishment and growth of vegetation in early succession. Ecocline - series of biotypes, which in a species that shows a genetic gradient correlated with gradual environment gradient. Ecological efficiency - the percentage of useful energy that passes from one trophic level in a food chain to another. Ecological equivalents - species that live far apart but in similar niches and ecosystems. Ecological pyramids - graphical representations of tropic structures in which the first or producer level forms the base and successive levels the tiers that make up the apex. Ecology – is the science and study of living organisms in relation to their environment. Ecosystem - any space conceived by the beholder that supports an interdependent community of organisms of different species that equitably share energy and nutrient resources; community sustainably interacting with environment Page | 3  Refresher Course for Forestry Graduates 2024 Ecotone - where two community types come together, such as a forest and field, species in the zone between them includes both forest and field species and some additional species that do not exist in either forest or field Ecotope (Biotope) - the smallest ecologically distinctive area within a landscape classification system. Ecotype - a genetically differentiated subpopulation evolved to remain within its habitat. Edge effect - the unique properties in an ecotone (plant variety, animal density, biological diversity), the zone where two communities meet. Eluviation - movement of humus, chemical substances, and mineral particles from the upper layers of a soil to lower layers by the downward movement of water through the soil profile. Emigration - movement of part of a population permanently out of an area. Endemic species - are organisms unique only to the area and found nowhere else. Entropy - disorder or unproductive energy in a given system. It tends to increase over time. Environment - is the sum of all factors that allows an organism, population and community to live, e.g., sunlight, water, nutrients, carbon dioxide, temperature, other living creatures including man (social factor). Equilibrium turnover rate – change in species composition per unit time when immigration equals extinction. Eutrophication - a gradual nutrient enrichment that increases organic matter production, as with a lake that absorbs waves of nutrient runoffs. Evenness – degree of equitability in the distribution of individuals among group of species. Evolution - simply means genetic change in a line of descent over the generations. Food chain - the path of food energy transfer from green plants (primary producers) to grazers (primary consumers), omnivores and carnivores (secondary consumers), and to their predators (top carnivores). Food web - the interconnection of all food chains in an ecosystem. Forest - a land area of more than 0.5 ha, with a tree canopy cover of more than 10%, which is not primarily under agricultural or other specific non-forest land use; a product of evolution and coevolution with unique flora and fauna Formation – includes major types of vegetation with peculiar physiognomy. (e.g., appearance) determined mainly by prevailing climate Frequency - an estimate of the change of finding individuals of species within a sample area of a particular size and shape. Fundamental niche - for a given species, the ideal range of suitable conditions without competition or predators. Gap – opening made in a forest canopy by some small disturbance that influences the development of vegetation beneath. Gene flow - the proliferation of alleles (different versions of the same gene) across populations. Page | 4  Refresher Course for Forestry Graduates 2024 Genetic diversity - genetic variability found in a population due to the genetic combinations of its individuals. Genetic drift - random fluctuation in allele frequencies over time due to chance occurrences alone Geographical range - geographical limits of the ecologist range; geographic extent of actual occurrences of a species. Gradient - a gradual of an environment factor in space. Gross production – energy fixed pert unit area by photosynthetic activity of plants before respiration. Habitat – is a place where an organism or species population or a community thrives (i.e., terrestrial habitats-forest, grasslands, deserts, etc.) Herbivore – organism that eats plants only. Heterotroph - an organism that cannot produce its own food and so must get it from other organisms. Holocoenotic principle - principle that an environment acts as a whole unit because of lack of barriers to the interaction of its component factors; applicable also to an ecosystem. Home range - an area that an animal regularly frequents. Homeostasis - the tendency for biological system to resist change and to remain in a state of equilibrium. Hydrological cycle - the ongoing transformation of water in the biosphere from ocean water evaporation to clouds, rain, groundwater and runoff, storage in organisms, etc. until its return to the oceans. Illuviation - accumulation of soil materials (clay, humus, iron, etc.) leached from one soil layer or horizon into another. Immobilization - the tendency withholding of energy or nutrient from the organic cycle; cf. mineralization and mobilization. Immigration - arrival of new individuals into a habitat or population. Importance value - sum of relative density, relative dominance, and relative frequency of a species in a community. Indigenous species - are organisms native to the area. A subset of indigenous species are endemic. Interference competition - occurs when an organism defends a resource, even if the resource is not in short supply Interspecific - between individuals of different species. Intraspecific - between individuals of same species. Island biogeography - study of distribution of organisms and community structure on islands. Lentic - still water (pond, lake, etc.); also, organisms living in it. Lotic - flowing water, as in a river or stream. Page | 5  Refresher Course for Forestry Graduates 2024 Macrodecomposer – animals that eat detritus or litter, like earthworms and termites (faunal decomposer). Microclimate - the climate of small locales. Microdecomposer – actinomycete, bacteria and fungi that break detritus or litter by means of enzymes to reduce them into small organic substances that could pass through cell wall (Osmotroph=to pass through; (Saprotrophs=dead remains); (Flora decomposer). Microevolution - refers to changes in the allele frequencies of a population over time. Migration - shifting of home range usually concerted and directional, and often over a considerable distance, in response to seasonal or other periodic changes in the environment. Moder - type of forest humus layer in which plant fragments and mineral particles form loose netlike structures held together by a chain of small arthropod droppings. Monotypic species - one population of one morphological type - i.e., Apitong Mor - type of forest humus layer of unincorporated organic matter usually matted, compacted, or both and distinct from mineral soil Mull - humus that contains appreciable amounts of mineral bases and forms a humus-rich layer of forested soil consisting of mixed organic and mineral matter. Mutation - a random change in one or more genes of an organism. Mutualism – population A and B benefits one another; the relationship is obligatory. Natural selection - change or stabilization of allele frequencies owing to differences in survival and reproduction among variant individuals of a population Neutralism - hypothesized situation in which two populations have no effect on each other at all. Net production - accumulation of total biomass over a given period of time after respiration is deducted from gross production in plants and from assimilated energy in consumer organisms. Niche – the functional role of the population as member of the ecosystem (or occupational trade/profession of the population in the community). Nutrient cycling - the cycling of nutrients through the environment and its inhabitants from soil to plants to animals and back to soil. Obligate - a species confined to a narrow range of conditions. Omnivore - an organism that eats both plants and animals. Organic cycle - the flow of energy or materials through the ecosystem that results from the activities it is useful to separate energy flow, nutrient cycle, water cycle and carbon cycle. Patch - a relatively homogenous area that differs from its surroundings. Parasitism – population A the parasite lives in population B the host, the latter is limited. Phagotroph - an organism that obtains nutrients through the ingestion of solid organic matter. Physiognomy - the external features of vegetation. Page | 6  Refresher Course for Forestry Graduates 2024 Polytypic species - > 1 populations, each population has unique morphological, ecological and geographic range peculiarities i.e., Almaciga, Guijo, white lauan & most species. Polymorphic species - a population in a species having individuals with heterogeneous in phenotypic appearances. Population - is a set of organisms of a species living in a locality at any given time; a subset of a species that exist in a particular locality within the geographic range of the species. Predation – population A the predator eats population B the prey, the latter is limited. Primary Production - producer’s production (plants); production of biomass by photosynthetic and chemosynthetic autotrophs. Producers - are organisms that produce their own food (ecological jargon is autotroph which is from Greek auto =self and trophe =nourishment), also primary producer is used. Productivity - the rate at which a group of organisms produces biomass. Protocooperation – population A and B benefits one another but the relationship is not obligatory. Pyramid of energy flow (Trophic pyramid) - a diagram showing the flow of energy through the trophic levels of a food chain or web. Pyramid of energy - diagrammatic representation of the flow of energy through different trophic level. Pyramid of numbers - diagrammatic representation of the number of individual organisms present at each trophic level in an ecosystem. Reservoir pool - is the large, slow-moving and biologically inert portion of the biogeochemical cycle. Resource competition - occurs when a number of organisms utilize a common resource that is scarce. Richness - the number of diverse species occupying a particular area. Saprotroph - organism which gets its energy from non-living organic matter. Scrub - small or low bushes or trees. Secondary production - consumer’s production (animals); production by the macroconsumer levels Sedimentary cycles - involve phosphorous and other solid nutrients move from land to the seafloor and return to dry land only by way of geological uplifting (takes M years). Speciation - formation of a new species. Species - any group of actually or potentially interbreeding populations that are genetically isolated from other such groups (Mayr, 1971). Species-area curve - species richness tends to increase in roomier areas. Stabilizing selection - mode of selection that tends to counter mutation, geneflow and genetic drift and it preserves the most common phenotypes. Page | 7  Refresher Course for Forestry Graduates 2024 Stochastic extinction - extinction caused by some random environmental event. Succession - the gradual replacement of one plant community by another. Symbiosis - a mutually beneficial relationship between two species. Sympatric speciation - the division of one species into two, but in the same geographical locale. Synecology - tries to link processes that bind ecosystem parts together into a whole system. Synusia - life forms of similar niches, which form the forest community. Territory - the area defended by an individual animal, pair, or family group against other members of the species (and sometimes against of other species), particularly during the breeding season. Trophic level – functional classification of organisms in an ecosystem according to feeding relationships from first-level autotrophs through succeeding levels of herbivores and carnivores. Trophic structure - refers to the way in which organisms utilize food resources and hence where energy transfer occurs within an ecosystem. Weather - atmospheric condition daily; short term troposphere changes (i.e., precipitation, temperature, sunlight/cloud cover, pressure, humidity, wind). Page | 8  Refresher Course for Forestry Graduates 2024 FOREST ECOLOGY The study and science of forest ecosystem. It deals with the interrelationships between various trees, plants, and other living organisms that make up the community and with the interrelationships between those organisms and the physical environment in which they exist. Organizations of life 1. Species - a group of organisms that can breed with each other. 2. Population - an interbreeding group of individuals belonging to a species living together in a locality. 3. Community - a group of individuals belonging to various populations (i.e., of different species) living together in a given locality. 4. Ecosystem - community of different species interacting with one another and with the chemical and physical factor making up its nonliving environment. Basic concepts of ecology 1. Everything is related to everything else. 2. There is a strength and quantity in the unity of differences. 3. Consumption must not exceed production. 4. Everything in nature has a purpose. 5. Nature is more concerned in improving quality than increasing quantity. 6. The tendency is towards an ecosystem more efficient and effective in its resources. I. APPROACHES IN STUDYING FOREST ECOLOGY A. Synecology/Community ecology - deals with ecological interrelationships among communities of organisms; tries to link processes that bind ecosystem parts together into a whole system. Example of the study: 1. Nutrient cycling pattern of a community 2. Productivity of the green plants as a whole in the community 3. Measuring the microclimate in the forest canopy B. Autecology/Population ecology - deals with the dynamics of populations and how these populations interact with the environment; how the population sizes of species groups change over time and space. Example of the study: 1. The life history and the response to its environment of a single individual or species 2. The abundance, distribution, productivity , and/or dynamics of a group of organisms of the same type (a single-species population) 3. The interaction of organism with other organism of different species Page | 9  Refresher Course for Forestry Graduates 2024 II. THE ECOSYSTEM CONCEPT What is an Ecosystem? A bounded ecological system consisting of all the organisms in an area and the physical environment with which they interact (Chapin et al. 2002). The sum of all the biological and non-biological parts of an area that interact to cause plants to grow and decay, soil or sediments to form, and the chemistry of water to change (Aber & Melillo 2001). It is a community sustainably interacting with the environment. It is composed of living and non-living components. Biotic – living, life-form occupying the ecosystem Abiotic – non-living, properties of environment Table 1. Components of the Ecosystem. Component Sub- Examples components Abiotic Inorganic these consist of simple chemical substances like all substances elements in the periodic table and their simple (non-living compounds like water (H2O), carbon dioxide (CO2), components) table salt (NaCl), nitrate (NO3), phosphate (PO4), sulphate (SO4), methane (CH4), etc. Except for methane, these do not burn. Organic consist of complex carbon-based hydrocarbon substances compounds like G glucose (C6H12O6), long-chain hydrocarbons G-G-..-G (e.g. carbohydrates, cellulose, etc.), small R hydrocarbons (pyruvate), amino acids (R-NH3), proteins, nucleic acids (DNA and RNA), etc. All of these decompose or burn giving off heat and the by-products CO2 and H2O. Climate regime used in different context, but in ecology, it refers to atmospheric variables like sunlight, rainfall (precipitation), temperature, humidity and wind velocity. Biotic Producers Green plants, photosynthetic bacteria, (mode of chemosynthetic bacteria nourishment) Macro- Herbivores, carnivores, omnivores, parasitic consumers animals Micro-consumers Fungi, bacteria, and actinomycetes Page | 10  Refresher Course for Forestry Graduates 2024 Living (biotic) components a. Producers (autotrophs) Photosynthetic organisms – green plants (unicellular or multicellular) make organic compounds by converting light energy to chemical energy (e.g. glucose) or in layman’s terms food. These organisms are also called photoautotrophs (light + nourishment) Chemosynthetic organisms – unicellular organisms (cousins of the bacteria) capable of breaking salts and capturing heat into food. These are referred to as chemoautotrophs (chemical + nourishment). b. Consumers (phagotrophs) heterotrophs which usually pass food through a mouth, pass intestines, and undigested material is expelled through an anal opening as fecal material. Herbivore – animals that eat only plants material Carnivore – eats animals only; secondary and higher order consumers Omnivore –consumer that eats both animal and plant materials. c. Decomposers (saprotrophs) are heterotrophs that team together in effecting biodegradation of dead animal, plant and microbe bodies which are divided into two groups: Macrodecomposer – animals that eat detritus or litter, like earthworms and termites (faunal Decomposer). Microdecomposer – actinomycetes, bacteria, and fungi that break detritus or litter by means of enzymes to reduce them into small organic substances that could pass through cell wall (Osmotroph=to pass through); (Saprotrophs=dead remains); (flora decomposer) Properties common to all ecosystems 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” 6. The persistence of the system to function through time or simply “sustainability” Kinds of ecosystems 1. Natural (i.e., ecosystems as pure outcomes of evolution and co-evolution) 2. Artificial (i.e., ecosystems that are outcomes of human doing, or ecosystems that are cultural in its development and maintenance). Page | 11  Refresher Course for Forestry Graduates 2024 Troubleshooting ecosystems concept: Philosophical perspectives Two Schools of Thoughts A. Holistic school of ecology: Clements et al., 1916, 1928 Ecosystem is a big organismic unit or superorganism Ecological succession: born, grow, mature, & die Ecotone (boundaries of Ecosystem that overlap) Entitation process precedes field sampling B. Individualistic school of ecology: Gleason et al., 1926 An accidental rendezvous of fit individuals in multidimensional gradient of factors No ecotone Field sampling observation precedes vegetation classification III. ECOSYSTEMS ENERGETICS 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 food 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 system to represent waste. Now, here is the equation that applies the first law Gross primary production (GPP) = Net primary production (NPP) + Plant respiration 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 the ever presence of waste.” By rearranging the formula above, this law is demonstrated by Net Primary Production = Gross primary production – Plant respiration (Rs) The Net primary production (NPP) in turn is converted to its components namely (1) primary producer biomass, (2) plant litter and mortality, and (3) herbivory. 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 process of eating and being eaten and is involved in the transfer of energy in the ecosystem. There are two kinds of food chain depending upon where the food transfer originates. If it 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-and-be-eaten process continues up to the top consumer (also called terminal or nth consumer). If it originates from deposited litter composed of dead animal and plant residues and then energy is first availed by Page | 12  Refresher Course for Forestry Graduates 2024 microconsumers, in turn eaten by macroconsumers up to top consumer, the food chain is called detritus food chain. The interlocking pattern formed by a series of interconnecting food chains is called food web. Concept of Ecosystem Efficiency THE FLOW OF ENERGY: PRIMARY PRODUCTION TO HIGHER TROPHIC LEVELS Food chain - transfer of food energy from one trophic level to the next until the food reaches the terminal or N-th consumer in a more or less linear manner. Food web - complex non-linear eaten and be eaten process; interlocking food transfer among trophic components of the community Ecological Pyramid – reflection of 2nd Law of Thermodynamics Pyramid of numbers represents the number of organisms in each trophic level Pyramid of biomass is a representation of the amount of energy contained in biomass, at different trophic levels for a given point in time. In general, the Page | 13  Refresher Course for Forestry Graduates 2024 higher trophic levels would have less total biomass than those below, because less energy is available to them. Pyramid of energy, which shows rates of production rather than standing crop. IV. BIOGEOCHEMICAL CYCLE This concept refers to the circular movement (natural pathways) of essential nutrients of living matter in the biosphere. Elements flow in various forms from the non-living (abiotic- water, land, and air) components of the biosphere to the living (biotic - biosphere) components and back. Refers the biological, geological, and chemical aspects of each cycle (i.e., Hydrogen cycle, Carbon cycle, Nitrogen cycle, Phosphorous cycle, and Sulfur cycle) Systems according to Energy and Material Flow 1. Open system - allows both matter and energy exchange with its environment, i.e., biophysical systems (from cell to community levels) 2. Closed system - closed to material exchange but open to energy flow with the external environment 3. Isolated system - do not allow both matter and energy exchange with an environment; movement of matter and energy is confined within the system Two compartments of the Biogeochemical cycle 1. Reservoir (nutrient) pool - is the large, slow-moving and biologically inert portion of the biogeochemical cycle. a. Gaseous compartment (includes N, C, O à origin of H20, O2, CO2, N2) – reservoir is air or ocean (via evaporation) b. Sedimentary compartment (origin of Phosphorous, Potassium, Sulfur, Calcium, Magnesium, Zinc, and more earth-bound elements) 2. Cycling (exchange) pool - is the small but rapidly-moving portion of the biogeochemical cycle that is biologically active Page | 14  Refresher Course for Forestry Graduates 2024 Gaseous compartment-based nutrient cycles 1. Hydrologic/Water cycle The hydrologic cycle represents the processes and pathways involved in the cyclical movement of water from the land bodies of water, to the atmosphere and back to land. The cycle is illustrated as beginning with the evaporation of water from big bodies of water like oceans. The water vapor is then transported by masses of moving air. With favorable conditions, the water vapor is condensed to form clouds that may eventually result in the precipitation. Upon reaching the biosphere the precipitation is partitioned and dispersed in a number of ways. A large portion of it is retained as soil moisture which is ultimately returned to the returned to atmosphere through evaporation and transpiration. Some portion of the precipitation reaches the stream channels through overland flow. The remaining portion infiltrates the soil which either move laterally and the out to soil surface or move downward into the water table where it is temporarily stored before being released through springs and rivers at a later time. The water in the rivers generally flows to the lakes, the seas and the oceans while a portion of it is lost to evaporation. 2. Nitrogen cycle The process by which nitrogen enters living organisms (the nitrogen is absorbed into green plants in the form of nitrates, the plants are then eaten by animals, through the animal’s excreta or when an animal or a plant dies). 3. Carbon cycle The carbon atoms from carbon dioxide are incorporated into organic compounds in plants during photosynthesis. They are then oxidized into carbon dioxide again during respiration by the plants or by herbivores, which eat them and by carnivores, which eat the herbivores, thus releasing carbon to go round the cycle again. Sedimentary compartment-based nutrient cycle: 1. Phosphorus cycle The phosphorus cycle is a relatively simple cycle. This is because phosphorus does not have an atmospheric component; that is, phosphorus is not moved around by the wind or the rain. Phosphorus tends to cycle only locally over short time periods. Exact rates of movement of phosphorus between different components of ecosystem vary. Any long-distance transfers of phosphorus involve movement from land to sediments in the sea, and then back to land. The Earth’s crust is the main storehouse for this particular mineral. 2. Sulfur cycle The elemental Sulfur is common in hot springs and volcanic emissions. Aeration oxidizes sulfur into H2S (hydrogen sulfide), but further oxidation of H2S converts to SO4-. These transformations are mediated by various series of sulfur bacteria. SO4- is available for plant nutrition. However, combustion of organic matter including the burning of fossil fuels releases sulfur into the atmosphere. When this sulfur is Page | 15  Refresher Course for Forestry Graduates 2024 dissolved by precipitation, it becomes acidified as sulfuric acid, H2SO4. Rain containing sulfuric acid is called acid rain. Acid rain can inhibit the mineralization of phosphorous in the soil and this could spell serious phosphorous deficiency among plants including trees and hence threaten even vast tracts of forests. Sulfur is a nutrient that is very important components of certain amino acids, the building blocks of enzymes and proteins. V. POPULATION ECOLOGY Principles pertaining to limiting factors Response of population to environmental gradients or variables is believed to be controlled by so-called “principles of limiting factors.” The one proposed by Liebig is the law of the minimum and the one proposed by Shelford is the law of tolerance. Principles of limiting factors - too much or too little of any abiotic factor can limit or prevent growth of a population of a species in an ecosystem Law of the minimum (Liebig’s law) - Introduced by Carl Sprengel (1828) and later popularized by Justus von Liebig. It states that given all nutrients are adequate in supply, the one factor in short supply is the limiting factor. Law of tolerance (Shelford’s law) - Proposed by Victor Shelford in 1913. This is an extension of the Law of the Minimum. 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 the minimum threshold limits is the tolerance range of an organism to a factor (physical environment). Optimum, zone of stress, limits of tolerance a. Optimum - the point that supports the maximum growth. b. Optimal range - the maximum range growth usually occurs over a range of several degrees. c. Range of tolerance - the entire span that allows any growth at all. d. Limits of tolerance - the points at the high and low ends of the range of tolerance. e. Zones of tolerance - between the optimum range and the high or low limit of tolerance. Population Growth and Carrying Capacity Population growth 1. Exponential growth The growth produced when the base population increases by a given percentage (as opposed to a given amount) each year. It is by doubling again and again, each doubling occurring in the same period of time. It produces a J-shaped curve. Page | 16  Refresher Course for Forestry Graduates 2024 Biotic potential - is the capacity of a population for increase. It is often represented by the symbol r (also called intrinsic rate of natural increase). 2. Logistic growth The population increase exponentially up to a point, and then suddenly level off as resources become scarce (sigmoid growth curve). Carrying Capacity a. An ecosystem can support only a given number of individuals at a given time. When the capacity level exceeded, an imbalance in the ecosystem occurs. b. Carrying capacity is the size of the population of users a resource is able to keep in good condition. Or a number of factors in the environment, such as food, oxygen, diseases, predators and space, determine the number of organisms that can survive in a given area. Organizations in population Three basic mating systems in a population: 1) Monogamy - persistent pair bond is formed between one male and one female. 2) Polygamy - unions involve a bond between a single member of one sex and several of the other sex. 3) Promiscuity - the individuals meet for copulation but no continuing relationship is established. Habitat vs. Niche The habitat of a population is its favorite place in a locality (or its address!), i.e. repeated places where members are nourished, grow, mature, reproduce and safely concealed from natural enemies, thus, its persistence in the ecosystem The functional role of the population as member of the ecosystem is its niche (or the occupational trade/profession of the population in the community). Hutchinson’s Fundamental Niche Concept Niche is a set of multidimensional tolerance ranges in the environment that permits a population to persist in a given time and space Fundamental niche is a set of points in an abstract n-dimensional space -- environmental parameters-- within which the population is permitted to exist indefinitely Page | 17  Refresher Course for Forestry Graduates 2024 Ecological Compression and Release Ecological compression is true when the realized niche shrinks à due to an increasing environmental pressure(s) that limits the living space towards threshold limits. Ecological release is true when the said environmental pressures relax and the realized niche expands and approaches the population’s fundamental niche. ECOLOGICAL INTERACTIONS/ SYMBIOTIC RELATIONSHIP 1. Protocooperation 2. Mutualism 3. Competition 4. Predation 5. Parasitism 6. Commensalism 7. Amensalism 8. Neutralism COMPETITION THEORY Competitive Exclusion Principle (Gause’s law) In a physical space, which corresponds to a point in the niche space belonging to the fundamental niche of two populations (different species), only one of the populations will persist/can be present in a physical space corresponding to a point in the niche space, but if this point is in the fundamental niche of any other population, then the theory has no way of predicting which species will be present.) No two populations (or species) occupy the same niches! - Georgii Frantsevich Gause Resource partitioning - species coexist within communities by reducing the size of their niche to prevent overlap. Page | 18  Refresher Course for Forestry Graduates 2024 LIFE TABLES, SURVIVORSHIP CURVES, AND POPULATION GROWTH Life table is a record of survival and reproductive rates in a population, broken out by age, size, or developmental stage (e.g., egg, hatchling, juvenile, adult). Applications: Predicting the growth and decline of populations In species conservation efforts Information obtained from a life table Population age structure No. of young individuals? Old individuals? Reproductive age individuals? Population growth rate How fast is the population size growing/shrinking? Population survivorship patterns What age group does most mortality occur? in the very young/old age group? VI. EVOLUTION AND ADAPTATION Evolution - genetic change in a line of descent over generations Macroevolution: Large scale evolution of groups of species (Speciation) Microevolution: changes in allele frequencies of a population over time (genetic variation) Evolution 1. Mutation - it is a transmissible change in structure of a gene or chromosome. It provides new alleles, which are the raw material for evolutionary change. 2. Gene flow - also called gene migration. It is the exchange of genetic material between populations or the movement of alleles among populations by migration of breeding individuals. 3. Nonrandom mating - involves inbreeding (results in increased frequency of homozygotes at all loci) and assortative mating (results in increased frequency of homozygotes at only certain loci). 4. Genetic drift - refers to changes in allele frequencies of a gene pool due to chance. 5. Natural selection - the differential reproduction and survival of individuals that results in elimination of maladaptive traits from a population. Survival of the fittest - the concept that individuals best adapted to cope w/ both biotic and abiotic factors in their environment are the fittest and most likely to survive and reproduce. R and K selection R selection - rapid growth and occupation through early reproduction, short life spans, low biomass, and lots of offspring. K selection - species in stable environments tend to live longer and produce fewer, and sometimes larger, offspring. Three types of natural selection 1. Directional selection - selection favoring individuals at one extreme of the phenotype in the population. 2. Stabilizing selection - occurs when an intermediate phenotype is favored. 3. Disruptive selection - two or more extreme phenotypes are favored over any intermediate phenotype. Page | 19  Refresher Course for Forestry Graduates 2024 Species Biological Concept - any group of actually or potentially interbreeding populations that are reproductively isolated from other such groups (Mayr, 1971); monotypic, polytypic, polymorphic Species Concepts Typological/Morphological Evolutionary Genealogical/Phylogenetic Ecological Cohesive Biological Population - is a set of organisms of a species living in a locality at any given time; (pioneer, climax, sympatric, allopatric population) Conspecific populations: populations of the same species (ecotypes, cline, hybrid, subspecies, forma, variety, race) Adaptation Any inheritable characteristic that increases an organism’s ability to survive and reproduce is called an adaptation = natural selection Adaptations can involve: 1. body parts or structures; 2. colors, like those that make camouflage or mimicry possible; 3. physiological functions, like the way a plant carries out photosynthesis Types of Evolution based on Adaptation Convergent evolution - the independent development of similar adaptations in two species with similar niche e.g., Cactus (Cactaceae) vs Euphorbia (Euphorbiaceae) Divergent evolution - evolution leading to modification of the basic pattern to serve different functions (homologous structures), enabling descendants to fill a wide variety of ecological niches Co-evolution - species that interact closely may become adapted to one another through a process called co-evolution; can occur as a result of feeding relationships e.g., The hawk moth Xanthopan morganii praedicta uses its long, specially adapted proboscis to pollinate the Madagascar star orchid (Angraecum sesquipedale). VII. ECOLOGICAL SUCCESSION The change in species composition of an ecosystem. It is a series of progressive changes in the species that make up a community over time Plant succession: is a directional, cumulative change in the species that occupy a given area; time involved: 1-500 years Page | 20  Refresher Course for Forestry Graduates 2024 Primary succession – process of creating life in an area where no life previously existed Types of Primary Succession (based on substrate) If it starts on a wet substrate: hydrarch If it starts on dry surface like an exposed rock: xerarch Secondary succession process of re-stabilization that follows a disturbance in an area where life has previously existed area/gap disturbed (by fire, typhoon, flood, and other natural or human disturbances) and previously vegetated Succession Process 1. Nudation, the exposure of a new surface in a primary succession or the clearing away of previous vegetation in secondary succession. 2. Migration of seeds, spores, or vegetative propagules from adjacent areas, though in secondary succession many of these are already present in the soil. 3. Ecesis, the germination, early growth, and establishment of plants. 4. Competition, among the established plants. 5. Reaction, the autogenic effects of plants on the habitat. 6. Stabilization, the climax. VIII. PHYSICAL ENVIRONMENT AS DETERMINANT TO TERRESTRIAL ECOSYSTEMS/BIOMES Biome A geographical area that has a particular climate and sustains a specific community of plants and animals (i.e. a type of ecosystem) The main factors affecting the distribution of biomes are temperature and rainfall These factors vary according to latitude and longitude, elevation, and proximity to the sea How does rainfall and temperature affect the distribution of biomes? Temperature is influential because it affects the rate of metabolism – the phases in the life cycles of many organisms are temperature dependent The availability of fresh water (both in the soil and in rivers and lakes) is critical to the growth and nutrition of organisms Rainfall and warmer temperatures are more common near the equator and less common at the poles Page | 21  Refresher Course for Forestry Graduates 2024 Major formation or biomes of the biosphere 1. Tundra - areas in arctic and alpine (high mountains) regions characterized by bare ground, absence of mosses, lichens, sedges, forbs and low shrubs. 2. Boreal forest - coniferous forests of the cold temperate latitudes. 3. Steppes and prairies - natural grasslands of the temperate zone 4. Savannah - tropical grassland, usually with scattered trees or shrubs. 5. Temperate deciduous forest - Oak Forest of the mild temperate zone. 6. Desert – an area within which the rate of evaporation exceeds the rate of precipitation most of the time. 7. Tropical deciduous forest of dry monsoon seasonal tropics 8. Tropical rainforests Reference: Odum, E.P. 1971. Fundamentals of Ecology. New York: John Wiley and Sons, Inc. Page | 22