Environmental Engineering Reference
In-Depth Information
determine the net benefits of biofuel production in terms of carbon stocks and fluxes. However, there
is another important consideration that adds further complexity to the assessment of net effects on
climate change mitigation, which is ultimately the key concern. The net effects of biofuel production
also need to be assessed in relation to their effects on global warming, which is not solely dependent
on atmospheric concentrations of CO
2
and other climate change gases. A recent modeling study by
Bala et al. (2007) determined that the difference in albedo between different types of vegetation can
have a considerable effect on global warming. Particularly in temperate and boreal regions, forests
may reflect less radiation than nonforest land cover. This is because forests usually have a darker hue
than grasslands or bare ground and because there is less apparent snow cover in forests. However, this
“albedo effect” is much less relevant in subtropical and tropical regions (Bala et al. 2007). Although
there is still some uncertainty about the net effects of albedo versus carbon sequestration between
different land uses that may be considered for biofuel production or climate change mitigation, it is
clear that this is an important factor that needs to be taken into consideration.
6.5 toWard a dIverse BIoenerGy PortFolIo
Biofuels have the potential to provide win-win scenarios for energy production and the maintenance
and enhancement of biodiversity. However, as clearly indicated in this chapter, this relationship is
not a given and will require the thoughtful and deliberate selection of species and cropping systems.
Species and cropping systems will need to be tailored to site and landscape-specific limitations and
opportunities. From a practical production efficiency standpoint, there is a strong desire to identify
a narrow suite of easy to work generalist species as major feedstocks. However, a diverse portfolio
of dedicated bioenergy crops and residue streams would be more advantageous from a systems
ecology perspective. The more species used and the more closely bioenergy plantations resemble
natural ecosystems, the lower the risk of catastrophic crop losses due to new and emerging pests and
diseases and/or drought and environmental change.
As the emerging bioeconomy continues to gather momentum, second-generation biofuels will
likely have a distinctive advantage on the ecological balance sheet. These feedstocks, as currently
envisioned, may be less likely to lead to habitat loss because they use residues from contemporary
forestry and agricultural practices and in many cases have dedicated plantings that can be grown
on land that has already been cleared for agriculture but is marginal for that use. When based
on native species, conservation and production objectives may be achieved simultaneously (e.g.,
restoration of native grasslands as a source of cellulosic ethanol). In formerly forested regions,
reforestation/plantation establishment may be preferable and could provide additional habitat to
declining forest species.
reFerences
Allen RB, Buchanan PK, Clinton PW, Cone AJ (2000) Composition and diversity of fungi on decaying logs in
a New Zealand temperate beech (Nothofagus) forest.
Can J For Res
30:1025-1033
Amezaga I (1997) Forest characteristics affecting the rate of shoot pruning by the pine shoot beetle (
Tomicus
piniperda
L) in
Pinus radiata
D Don and
P. sylvestris
L plantations.
Forestry
70:129-137
Bala G, Caldiera K, Wickett M, Phillips TJ, Lobell DB, Delire C, Mirin A (2007) Combined climate and
carbon-cycle effects of large-scale deforestation.
Proc Natl Acad Sci USA
104:6550-6555
Barlow J, Gardner TA, Araujo IS, Ávila-Pires TC, Bonaldo AB, Costa JE, Esposito MC, Ferreira LV, Hawes
J, Hernandez MIM, et al. (2007) Quantifying the biodiversity value of tropical primary, secondary, and
plantation forests.
Proc Natl Acad Sci USA
104:18555-18560
Barney JN, Ditomaso JM (2008) Nonnative species and bioenergy: Are we cultivating the next invader?
Bioscience
58:64-70
Batjes NH (1998) Mitigation of atmospheric CO
2
concentrations by increasing carbon sequestration in the soil.
Biol Fertility Soil
27:230-235
Berndt LA, Brockerhoff EG, Jactel H (2008) Relevance of exotic pine plantations as a surrogate habitat for
ground beetles (Carabidae) where native forest is rare.
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