Ecosystem forested

The interactions of air pollutants with forests at low-dose concentrations result in imperceptible effects on the natural biological cycles of these species. In some instances, these interactions may be beneficial to the forest ecosystem. Forests, as well as other natural systems, act as sinks for the removal of trace gases from the atmosphere. 

W. F. Harris, D. Santantonio, and D. McGinty. The dynamic below-ground ecosystem, Forests Fresh Perspectives from Ecosystem Analy.sis. (R. H. Waring, ed.), Oregon State University Press, Corvallis, 1980, p. 119. 

Houghton, R. A. (1996). Land-use change and terrestrial carbon The temporal record. In Forest Ecosystems, Forest Management and the Global Carbon Cycle" (M, J, Apps and D. T. Price, Ed.), pp. 117- 134. NATO ASI Series, Springer-Verlag, Berlin, Heidelberg. 

Tietema, A., Emmett, R B.A., Gundersen, Kjpnaas, O.J. and Koopmans, C.J. (1998). The fate of N-labelled nitrogen deposition in coniferous forest ecosystems. Forest Ecology and Management, 101, 19-27. 

Carbon sequestration is the capture and storage of carbon that would otherwise be emitted or remain in the atmosphere. Terrestrial ecosystems, which consist of vegetation and soils containing microbial and invertebrate communities, sequester CO2 directly from the atmosphere. The terrestrial ecosystem is essentially a huge natural biological scrubber for CO2 from all sources of fossil fuel emission, such as automobiles, power plants, and industrial facilities. Terrestrial ecosystems (forests, vegetation, soils, farm crops, pastures, tundras, and wetlands) have a net carbon accumulation of about one-fourth of the amount emitted to the atmosphere from fossil fuels. 

It is likely that natural ecosystems (forest, grassland) emit no or only small amounts of ammonia because normally there is a deficit of fixed nitrogen in landscapes. Reported emissions factors over forests span three orders of magnitude and are likely be influenced by re-emission of wet deposited ammonium. Older publications considerably overestimated emission by using simple models considering soil ammonium concentrations obtained from relative decomposition and nitrification rates, where Henry s law gives the equilibrium concentration of ammonia gas in the soil, and a simplified diffusion equation yields the flux to the atmosphere, for example, Dawson (1977) calculated it to be about 47 Tg N yr b... 

World Resources Institute (2010) Industrial roundwood. www.wri.org/publication/pilot-analysis-global-ecosystems-forest-ecosystems. 

Vol. 40 Forest Ecosystems, Forest Management and the Global Carbon Cycle. 

Receptors. The receptor can be a person, animal, plant, material, or ecosystem. The criteria and hazardous air pollutants were so designated because, at sufficient concentrations, they can cause adverse health effects to human receptors. Some of the criteria pollutants also cause damage to plant receptors. An Air QuaUty Criteria Document (12) exists for each criteria pollutant and these documents summarize the most current Hterature concerning the effects of criteria pollutants on human health, animals, vegetation, and materials. The receptors which have generated much concern regarding acid deposition are certain aquatic and forest ecosystems, and there is also some concern that acid deposition adversely affects some materials. 

Under low-dose conditions, forest ecosystems act as sinks for atmospheric pollutants and in some instances as sources. As indicated in Chapter 7, the atmosphere, lithosphere, and oceans are involved in cycling carbon, nitrogen, oxygen, sulfur, and other elements through each subsystem with different time scales. Under low-dose conditions, forest and other biomass systems have been utilizing chemical compounds present in the atmosphere and releasing others to the atmosphere for thousands of years. Industrialization has increased the concentrations of NO2, SO2, and CO2 in the "clean background" atmosphere, and certain types of interactions with forest systems can be defined. 

The second level of interaction, the intermediate-dose level, can result in measurable effects on forest ecosystems. These effects consist of a reduction in forest growth, change in forest species, and susceptibility to forest pests. Both laboratory investigations and field studies show SO2 to be an inhibitor of forest growth. When various saplings have been exposed to SO2 in the laboratory, they show reduction in growth compared with unexposed... 

The third category for interactions is high dose (III). The effects produced by this level of interaction can be seen by the casual observer. The result of high-dose exposure is destruction or severe injury of the forest system. High-dose conditions are almost always associated with point source emissions. The pollutants most often involved are SO2 and hydrogen fluoride. Historically, the most harmful sources of pollution for surrounding forest ecosystems have been smelters and aluminum reduction plants. 

Smith, W, H., "Air Pollution and Forests Interaction between Air Contaminants and Forest Ecosystems," 2nd ed. Springer-Verlag, New York, 1990. 

What types of trace gases are released to the atmosphere by forest ecosystems ... 

Consider a lake with a smaU watershed in a forest ecosystem. The forest and vegetation can be considered as an acid concentrator. SO2, NO2, and acid aerosol are deposited on vegetation surfaces during dry periods and rainfalls they are washed to the soil floor by low-pH rainwater. Much of the acidity is neutralized by dissolving and mobilizing minerals in the soil. Aluminum, calcium, magnesium, sodium, and potassium are leached from the soil into surface waters. The ability of soils to tolerate acidic deposition is very dependent on the alkalinity of the soil. The soil structure in the... 

The documentation of regional level terrestrial consequences of acid deposition is complicated. For example, forested ecosystems m eastern North America can he influenced by other factors such as high atmospheric ozone concentrations, drought, insect outbreaks and disease, sometimes from non-native sources. However there is a general consensus on some impacts of acidic depositon on both soils and forests m sensitive regions. 

In a temperate forest ecosystem on Isle Royale, Michigan, ecologists found that it takes 762 pounds (346 kg) of plant food to support every 59 pounds (27 kg) of moose, and that 59 pounds of moose are required to support every one pound (0.45 kg) of wolf. The basic point is that massive amounts of energy do not flow from one trophic level to the next energy is lost at each stage of the food chain, so there are more plants than herbivores and more herbivores than carnivores. 

A 1999 study by the Institute of Terrestrial Ecology predicts that tropical rain forests will be able to continue to absorb carbon dioxide at the current rate of 2 billion tons per year until global temperatures rise by 8°F (4.5°C). At this point, evaporation rates will be high enough to decrease rainfall for the forests, leading to the collapse of tropical ecosystems. This collapse will decrease the amount of carbon... 

Sensitive ecosystems that cannot neutralize the unnatural levels of acidity are adversely affected. Soil nutrient systems may be altered with a resulting direct or indirect damage to forest. Aquatic habitats have been chemically altered and many lakes and streams no longer support the traditional life forms. Fish have been lost from many lakes with a resulting affect on other food-web elements. 

Contemporary forest declines were initiated about 1950-1960, virtually simultaneously throughout the industrial world at the same time as damage to aquatic systems and structures became apparent. A broad array of natural and anthropogenic stresses have been identified as components of a complex web of primary causal factors that vary in time and space, interact among each other, affect various plant growth and development systems and may result in the death of trees in mountainous ecosystems. As these ecosystems decline, the alterations in forest ecology, independent of the initial causal complex, become themselves additional stress factor complexes leading to further alterations. 

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