Forest plant products

Forests cover the 30% of the world s land. Forest trees form an important part of human society. Forests not only stabilize the environment but also provide essential components as well as protect landscapes. Forest trees nourish wild Hfe, support industries, and aid raral economies. Forest plants provide a wide variety of products resulting in direct and indirect benefits to society. Leaves, bark, flowers, roots, seeds, and wood are used to manufacture various industrial products such as fibers, resins, medicines, construction and building material, food, fuel, pulp, and paper [72, 73]. 

Pines are coniferous trees native to the northern hemisphere and grow well in acidic soil. These are the most important tree species for timber and wood pulp throughout the world. In Chile, Brazil, South Africa, Australia, and New Zealand, pines are the sources of timber. Pinewood is widely used in furniture, flooring, roofing, and other interior decoration work. 

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Nitrogen Limitation on Boreal Forest Plant Productivity... 

R. Fogel, Root turnover and productivity of coniferous forests, Plant Soil 71 75 (1983). 

The average value of wood productivity (in m /ha per year) is a function of the soil characteristics, seed genetics, micro-climate, cycle of cutting, and other parameters. For the average Brazilian situation, eucalyptus industrial forests, planted in poor lands (cerrado, a type of savanna, for example) and cut every 7 years, have a production of 20 t/ha per year (50% moisture) which permits production of 5 to 7.7 tons of methanol/ha per year. 

As small as one might think it to be, insect frass plays an important role in nutrient cycling in plant communities with consequences on plant productivity even under moderate levels of herbivory (e.g. Frost and Hunter, 2004). In turn, feeding by herbivores is strongly regulated by plant seeondary metabolism in its chemical defense expression (e.g. Rhoades, 1979, 1983). Alterations of forest nutrient dynamics by insects... 

Volatile organic compounds are contributed to the atmosphere by many forms of plant life, by way of conifers such as cedar, pine, and eucalyptus, and aromatic plants such as lavender, mint and sage. The pine forests of New England and the eucalyptus forests of the Blue Mountains in Australia contribute large masses of terpenes to the air above them. Terpenes are plant products biosynthetically derived from isoprene and have a formula of the type (C5H8)n where n is based on the number of isoprene units in the compound (Eq. 2.1). 

Moist tropical forests account for a substantial amount of global plant productivity. And several lines of evidence suggest that they may be sequestering signiheant amounts of anthropogenically released carbon at the present time. But there are also indications that the productivity of many of these forests is limited by low phosphorus availability. This has led to suggestions that moist tropical forests may be constrained in their ability to increase their growth rates in response to increases in atmospheric carbon dioxide concentrations. This notion is examined in this chapter. 

The nature of P mineralization in soils is a second factor mediating towards phosphorus availability not constraining tropical forest [CO2] responses. This is because, unlike nitrogen, phosphorus is mineralized independent of carbon in most soils. Thus, it has less potential to be locked up in the larger soil carbon pool that should occur as a result of increased plant productivity at higher [CO2]. 

Fig. 15.4. Simulated plant production (a), soil carbon (0-50 cm depth) and soil respiration (b), and nitrogen and phosphorus soil mineralization (c) for Hawaii humid tropical forest systems during 4.1 million years of soil development. Observed data are plotted on the graphs, and observed net primary production is assumed to be equal to 0.7 times annual soil respiration.

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