Rates of deforestation

Human activity, particularly in the developing world, continues to make it more difficult to sustain the world s biomass growth areas. It has been estimated that tropical forests are disappearing at a rate of tens of thousands of hm per year. Satellite imaging and field surveys show that Brazil alone has a deforestation rate of approximately 8 x 10 hm /yr (5). At a mean net carbon yield for tropical rain forests of 9.90 t/hm yr (4) (4.42 short ton /acreyr), this rate of deforestation corresponds to a loss of 79.2 x 10 t/yr of net biomass carbon productivity. 

The Amazon humid forest plays an important role in the water cycle and water balance of much of South American. Several model studies and field experiments show that large part of the rainfall in the region originates as water recycled in the forest. However, under the current rate of deforestation of no more than 10% per year, rainfall and streamflow observations across the basin do not exhibit any significant trends yet. 

Wood 1992). In addition, the ensuing road network and infrastructure left in the wake of these recent activities increased access to primary forest, precipitating further deforestation. By 1996, about 52 million hectares, nearly the size of France, had been deforested in Brazilian Amazonia (INPE 1998). At the average rate of deforestation from 1992 to 1996 (1.9 million hectares per year), another area equivalent to this figure will be added by the year 2025, a time frame within the career of many reading this book. 

Globally, the net carbon loss from tropical forests into the atmosphere from tropical deforestation and changes to secondary forest, pasture and crops, has been estimated (Seiler and Crutzen, 1980 Dickinson, 1981) to be about 1.0 X 10 kg carbon, or equivalent to about 17% of that due to fossil fuel burning. This amount tends to support the view that the current increase in atmospheric CO2 is primarily due to increased fossil fuel combustion (Niehaus, 1979 Broecker et d., 1979). Nevertheless, there is sufficient uncertainty in the basic data, e.g. the rate of deforestation and the amount of biomass, to permit wide variation in the final estimates. Thus, other estimates have suggested that the release of carbon due to tropical deforestation is 3 X 10 kg carbon or even more, with overall releases from biota estimated to approach 6 X 10 kg carbon (Wood-well, 1978 Woodwell et d., 1978). This latter amount is more or less equivalent to that released by fossil fuels. 

The net change in forest area is not the rate of deforestation but, rather, the rate of deforestation minus the rate of afforestation. 

While production of most bioplastics results in reduced carbon dioxide emissions compared to traditional alternatives, there are some real concerns that the creation of a global bioeconomy could contribute to an accelerated rate of deforestation if not managed effectively. There are associated concerns over the impact on water supply and soil erosion and bioplastics represent a 42% reduction in carbon footprint. On the other hand, bioplastic can be made from agricultural byproducts and also from used plastic bottles and other containers using microorganisms. 

Proposals to implement a biorefinery approach for platform chemical production have ignited a debate on whether biorefinery feedstock production threatens food security and increases the rate of deforestation (Ravindranath et al., 2008). It s worrying because the feedstock suitable for biorefinery implementation is procured primarily from forests. Any activity such as feedstock production, which puts considerable pressure on the forest cover, endangers natural heritage and biodiversity (Achten et al., 2013). This chapter discusses various forest-based feedstocks for biorefinery. Moreover, it seeks to elaborate the industrial applications of this feedstock, their characteristics and land requirements (essentially the extent of theoretical deforestation), their production, and procurement. Clearly the influence of biorefinery on woodlands will rely on the nature of the feedstock being used. For example, Brazil utilizes deforested land for sugarcane cultivation and subsequent ethanol production. However, in the case of Indonesia, rain forests were cleared for palm oil production. All of the biorefinery processes require cellulose as the raw material, and since the major source of cellulose in nature is in the form of trees, large-scale deforestation seems to be a plausible end scenario (Gao et al., 2011). 

---