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FOREST ECOLOGY
Revisiting the Forest Cover of the Philippines Estimates place forest cover in 1900 at 21 million has. (210,000 km^2 ) or 70% of the total land area. Many areas were already heavily damaged by this time in the Central Cordilleras and Ilocos by local action, while the Spanish were responsible for the cutting of the much-valued molave of the Central Visayas and the conversion of the marsh lands of Pangasinan and Culion which was reportedly already bald. The Americans introduced logging for export. 1920’s - Forest still covered 18 million hectares (180,000 km^2 ) or 60% of the total land area but the forests were under pressure because of the great demand for tropical hardwood for export to the U.S. Between 1900 and 1920, Romblon Island was completely deforested; the Central Plains of Luzon were also cleared, while Northen Bukidnon and Cotabato were opened up. By 1950 estimates place forest cover at 15 million hectares (150,000 km^2 ) or 50% of the total land area. Since 56% of the Philippines is classified as upland, the threshold in sustainable management was crossed in the 1945-50 period. FAO, 1963 put forest cover at 12 million hectares (120,000 km^2 ) or 40% of the total land area. The late 1960s is considered the start of a logging boom period. Logging concession areas increased from 4.5 million hectares to 11.6 million hectares. Forest covered 34% of the total land area or 10.2 million hectares (102,000 km^2 ). From 1977 to 1980, deforestation reached an all time high- over 300,000 hectares a year. By the end of the 1970s, the following islands
Forest Ecology Prepared by J.
del Rosario
were either almost completely deforested or had less than 5% forest cover: Polillo, Burias, Palaui, Tablas, Batanes Islands, Lubang, Marinduque, Ticao, Guimaras, Masbate, Siquijor, Cebu, Bohol, Samal, Siargao, Tawi-Tawi, Jolo and Camiguin. The Philippine forest was rapidly disappearing. The Swedish Space Corporation (SPOT) study of 1987 place forest cover at 6.9 million hectares (69,000 km^2 ) or 23.7% of the total land area. There were 2.7 million (27,000 km^2 ) hectares or 8.9% of the total land area of primary forest and this included mossy and pine forest. The Philippine-German Forestry Resource Inventory Project places forest cover at the end of 1987 at 22.2% or 6.6 million hectares. Since 1987, deforestation is estimated to have continued at a rate of 100,000 hectares per year. This means that at the beginning of 1999 , the Philippines will have 5. million hectares (55,000 km^2 ) or 18.3% of forest cover. LESSON 1: OVERVIEW ON FOREST ECOLOGY Lesson objectives: At the end of the lesson, you should be able to:
- discuss ecology and the importance of forest ecology;
- identify the functions of ecosystem; and
- discuss the species composition of a forest. Introduction Human activities are affecting the global environment in myriad ways, with numerous direct and indirect effects on ecosystems. The climate and atmospheric composition of Earth are changing rapidly. Humans have directly modified half of the ice-free terrestrial surface and use 40% of terrestrial production. Our actions are causing the sixth major extinction event in the history of life on Earth and are radically modifying the interactions among forests, fields, streams, and oceans.
- Aquatic ecology – basically the opposite of terrestrial ecology, aquatic ecology deals with the study of ecosystems found in bodies of water, be it the marine, freshwater, or the estuarine.
- Aquatic ecology focuses on the interactions among living organisms in a particular aquatic habitat which can directly affect various factors in the ecosystem.
- Such factors include competition for food and predation, temperature, nutrient, concentration, and oxygen demand.
- Microbial ecology – focuses on the study of how communities of microorganism establish themselves on abiotic substrates and how such organizations enable them to interact with each other.
- System ecology – tackles various abiotic factors like energy budget allocation and physical processes such as carbon cycle and biogeochemical cycles.
- Taxonomic ecology – branch of ecology that helps in the classification and identification of organisms, whether each act accordingly or antagonistically with each other in the community.
- Population ecology – is the study of the dynamics, structure, and distribution of populations rather than looking at the individual behavioral patterns of living organisms.
- Population ecology studies the various factors that affect population size, density, dispersion modes, and growth rate and mortality rate.
- Evolutionary ecology – is linked closely to population ecology.
- focuses on the physical and genetic changes that occurred among organisms and how such modifications were affected by ecological factors.
- Basically, it also considers the effect of forces like competition, predation, parasitism, and mutualism in the evolution of individual species, in a population, or in the entire community.
- Behavioral ecology – integrates the study of the interaction between survival value to the behavior of organisms and their offspring.
- Interestingly, it somehow related to evolutionary as it examines how an organism changes its behavior to ensure survival and perpetuation.
- Conservation ecology – studies the management of biodiversity through conservation and restoration methods.
- Applied ecology – application of knowledge, findings, and technological advances to understand real world situations and to address practical human problems.
- This includes applications like management of wildlife ad natural resources, epidemiology, and even natural disaster risk reduction and management.
- Physiological Ecology (ecophysiology) - is the study of how environmental factors influence the physiology of organisms.
- Community Ecology - is the study of interactions among individuals and populations of different species.
- Ecosystem Ecology (e.g. forest, river, ponds…) - is to a great extent about mass balances of elements and their interactions. The fluxes of elements are strongly coupled to each other, and often one limiting element regulates the fluxes of the others. This chapter gives an introduction to the most important elements and to some key concepts or cornerstones:
mass balance, limiting nutrients, optimality and steady state. At the ecosystem level we are interested in structural and functional attributes of the system as a whole: The reciprocal influences between patterns and processes, where patterns span scales from stands (e.g., the number of canopy layers) to landscapes (e.g., the distribution of community types or age classes across the landscape) to regions and the entire globe, and processes include all things that involve movement, change, or flux. Productivity - the conversion of solar energy and nonliving chemicals to plant chemical energy and mass through photosynthesis (primary productivity), and conversion of the energy and mass in plants to energy and mass in animals and microbes (secondary productivity). Food webs - the way in which energy is distributed among the organisms of the system. Cycling of matter. Stability or the processes that allow the system to adapt to uncertain and often catastrophic change in the environment. Interactions between land, air, and water.
- Landscape Ecology - study these reciprocal interactions between spatial patterns and ecological processes (Turner et al. 2003). Though the term landscape is often used to denote our intuitive sense of what the word means - roughly an area humans can see when standing on a high point - for ecologists landscapes occur at a variety of scales; an eagle has one landscape, a ground squirrel another, a beetle yet another. Whatever the scale, the scientific focus is on linkages between spatial pattern and process.
- Theoretical production ecology - tries to quantitatively study the growth of crops. The plant is treated as a kind of biological factory, which processes light, carbon dioxide, water and nutrients into harvestable parts. Main parameters kept into consideration are temperature, sunlight, standing crop biomass, plant production distribution, nutrient and water supply.
Ecosystem is a community of species interacting among themselves and with the physical
environment
Components of Ecosystems
• Abiotic substances - are the inorganic and organic substances not momentarily
present in living organisms.
• Producer organisms - are bacteria and plants which synthesize organic compounds.
They are autotrophic or self-productive.
• Consumer organisms - are animals which utilize the organic materials directly or
indirectly manufactured by plants.
• Decomposer organisms - are bacteria and fungi which degrade organic compounds.
Plant communities are broadly distributed into biomes based on the form of the dominant plant species. For example, grasslands are dominated by grasses, while forests are dominated by trees. Biomes are determined by regional climates, mostly temperature and precipitation, and follow general latitudinal trends. Within biomes, there may be many ecological communities, which are impacted not only by climate and a variety of smaller-scale features, including soils, hydrology, and disturbance regime. Biomes also change with elevation, high elevations often resembling those found at higher latitudes. Figure 5. Biomes of the world. Biomes are regions of similar climate and dominant plant types (Forseth, 2012). Source: http://bouchillonlifescience2.wikispaces.com/Coniferous+Forest+Key+Facts The Man and the Forest Soil and forest development During the last ice age the most of the middle and northern part of Europe was covered by sediments that were formed by physical weathering of rocks: argillaceous shale, marl slate, sandy shales, debris shales. Alluvial sands, eolian sediments as loess covered more or less big bed of the rest of older gests and soils formed in the periglacial space. Ice age sediments and covered older beds were without humus as it documents present carbon analysis. Humus reserves from older periods of soil formation ion were at the beginning of the ice age mineralized (fungus decomposition): decline of KAK and saturation by base could be linked according to the ion balance. It is possible to come out of: at the beginning of Holocene the possible acid bottom layers that were if the form of alder liquid soils or rock geests (compare Fiedle and Hofmanu 1991), so these materials were over layered more or less thick covers of inacid ice age sediments.
The present plant and animal state in our country is the result of the fluctuation of the climate at the end or tertiary period and at the beginning of quaternary period. In the ice age (mainly third and fourth icing) reached our country northern glacier and in the mountains there were local glaciers, it was tundra (birches, osier, sporadically pines) on the rest of the territory. In interglacials the climate was similar to present northern Yugoslavia or Bulgaria. The man did not influence the nature in the beginnings: in the older and middle stone age man lived on gathering and hunting. Firstly 25 thousands years ago he started with group hunting of bigger animals. The man was as a hunter, also as a hunting object of big beasts and he did not have more important influence on the number of animals. 10 or 8 thousand years ago it started warming (2 or 3 degrees more that today). The forests expanded, they encountered to the first agriculture which advanced firstly in e.g. Praha-Louny and Příbram regions. The direct alteration of forests is in the beginning of 18th century. Development of forestry and forest management Forests were originally free goods for a long time which use was restricted only by the territorial demands of settlers. While the farmed lands became relatively individual property, distant Lands, pastures and forests were for a long time common property (allmends). In the middle ages the ownership of lands - and forests was secured by the estate law guaranteed by the sovereign. While in the 12th century forests were in contracts of donation (e.g. 1169 kingVladislav) bound by word, in the 13th century the land was measured. In 1369 forests were measured in Rožumberk domain. The later data about the forest area in the region of the present Czech Republic date from the statistic inquiry (published in 1924). In the period till WWII. the lands were adapted by balance. From 1950 the data are the result of detailed inventory of all forests conducted by state organization (today The Department for Management Adaptation Brandýs nad Labem), from the beginning of 60s annually first as The Permanent Forest Inventory and from 1979 as The Collective Forest Management Plan (SLITP). In both cases the base was the data sum of valid forest maintenance plans. Species composition In the period of older atlantica (5500 - 4000 BC) pines and other trees give from the boreal period and expand to mixed oakwood, spruce and beech tree. In the period of younger atlantica (4000 - 2500 BC) spruce trees expand and there ascend beech tree and fir. The colonizaíion starts with uprooting, pasture and thin forests. In the subboreal period between 2500 - 500 BC spruce trees and mixed oakwood fall back and beech trees and firs ascend. The spruce tree overweighs in Šumava, in Jizerské hory with the altitude 750 m spruce trees form one third of substituted wood. In younger subatlantica (500 BC - 1300 AD) the mixed forests formed of beech trees and firs are in uplands, however in higher places the spruce trees outweigh. Total species composition of wood was influenced in the 1411 century by the settlement of suitable regions, that is of oakwood, pine trees, alders, lime trees and birch trees. In the first half of the 16th century the experiments of alien trees took place (sawn chestnut). It is spoken in the 20th century about the preference of some trees spoken during the 19th
b.1. Soil physical properties b.2. Soil chemical properties b.3. Soil fertility and soil productivity b.4. Land-use potential b.5. Soil temperature level b.6. Soil moisture b.7. Beneficial microorganism c. Climate c.1. Rainfall distribution c.2. Relative humidity c.3. Temperature c.4. Wind d. Topography d.1. Altitude/elevation d.2. Exposure from the sunlight d.3. Adverse climate e. Land-use System e.1. Land uses of surrounding areas e.2. Potential alternative uses of land e.3. Land value e.4. Accessibility
- Socio-economic Environment a. Exogenous factors (factors outside the forest ecology) a.1. Policies a.2. Needs FOREST ECOSYSTEM SERVICES Provisioning services – the production of food, fiber, water and medicines Regulating services – the control of climate and diseases Supporting services – nutrient cycling and crop pollination Cultural services – such as spiritual and recreational benefits. Protective and Ameliorative Roles
- Minimize soil erosion and surface run-off - has the potentials to contribute to the conservation/amelioration of soil, water, and microclimate. Trees minimize soil erosion and surface run-off in several ways: a. The tree canopies reduce the erosive capacity of rainfall through crown interception; b. The trees serve as windbreaks thus reducing velocities that cause soil erosion; c. The stems and roots as barriers against soil erosion. The trees can minimize surface run-off through: a. The canopies that intercepts the rainfall and the organic matters that accumulates on the surface soil serve as cover against rainfall impact thus minimizing soil compaction and increasing infiltration; b. The organic matter serves as cementing agent which promotes soil aggregation and therefore enhancing soil porosity and infiltration; c. The organic matter also serves as a “sponge” which increase the water holding capacity; d. The pores created by dead roots and by the penetrating root system increase water infiltration and absorb much of the water that percolates via the stem flow; and
e. The favorable soil and microclimate conditions under the tree canopies favor the activities of burrowing soil organisms such as earthworms thereby increasing porosity and infiltration. Note: The trees or woody perennial components could either minimize or enhance soil erosion. The effect depends on the height of the tree crown of the leaves, density of the crown and absence of soil cover.
- Minimize nutrient loss Forest vegetations and other organisms can reduce nutrient loss.
- Minimize landslide
- Trees can minimize landslides in step slopes when their roots anchor on the soil mass (Baconguis 1985).
- Tree roots also anchor deeper into the stable subsoil or unto the fractures or bedrocks and provide interlocking long fibrous binder within a weak soil mass (Zeimer 1981 as cited by Baconguis 1985).
- Hydrologically, trees intercept and transpire water, reducing water in the soil.
- Mechanically, tree roots anchor the soil (a factor of rooting depth ) and bind it (a factor of root density ).
- Tree roots do play a real role in providing mechanical coherence of the soil profile.
- Minimize pest and diseases
- The presence of different species in a Forest ecosystem makes it less susceptible to pest and disease attack.
- These diverse species influence each other through feeding interrelationships, thereby providing a mechanism for check and balance of each population.
- Forest Ecology can help reduce pesticide drift, and thus partially mitigate potential drift and negative impacts to pollinators, predators, and parasitoids in annual and perennial cropping systems.
- Amelioration of soil fertility Although litter fall is the major pathway of nutrient flow standing biomass to the soil, considerable amount of Nitrogen, Phosphorus, Calcium and Magnesium are leached from the tree canopy and returned to the soil, (Prichett 1979).
- Amelioration of soil properties (soil structure and texture) The tree roots loosen the topsoil and improve the subsoil porosity/ infiltration capacity when deep roots decompose.
