A general discussion on the impact of lignocellulosic bioenergy systems on biodiversity and water balance is given below.
6.2.2.1 Impact on biodiversity
Biological diversity, normally referred to as biodiversity, is defined by the United Nations Convention Biological Diversity (UNCBD, 1973) and the Millennium Ecosystem Assessment Board (MEA, 2005) as: “the variability among living organisms from all sources including, inter alia, terrestrial, marine, and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems”. The term is used to cover all forms of life, but for practical purposes, it is often used in reference to specific taxa, e.g. biodiversity of plants, biodiversity of mammals, biodiversity of insects, and others. In its
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most common usage it refers to the disappearance or decrease in abundance of naturally occurring (endemic or indigenous) species that are implied when ‘loss of biodiversity’ is being discussed (Von Maltitz et al., 2010). When considering biodiversity, it is often convenient to subdivide the landscape into units of similar biodiversity, such as habitat types or ecosystems. The habitat type is typically defined by eco-regions, biomes or broad vegetation type such as lowland forest, dry deciduous forest, grassland, wetlands when working at a global or national level, but it could be a more detailed local classification when working at a plantation level (Von Maltitz et al., 2010). Biodiversity is important in all ecosystem services, directly or indirectly, although the relationship is often quite complex and subtle. There is firm evidence that diverse ecosystems, in general, are both more productive and more resilient to stress than less diverse ecosystems (MEA, 2005). Figure 48, below, shows the pathways and processes by which biodiversity influences ecosystem services, and ecosystem services influence human wellbeing. The value of supporting services, most of the value of regulating services, and most of the aspects of biodiversity are contained within the value of the directly used provisioning and cultural services. These underlying elements can influence the direct services through altering the mean magnitude of the service (μ) or its variability in time (σ) or its variability in space (γ) (Amezaga et al., 2010: 85).
The deliberate simplification of ecosystems, for instance, through mechanised monocultural cropping using high inputs of nutrients, water and pesticides has been the key mechanism for increased provisioning services such as food and fuel over the past century. This has generally been at the cost of other services – even of other provisioning services – such as water and biodiversity (MEA, 2005). Biofuel expansion, if not carefully regulated, has the potential to have very high impacts on biodiversity, especially as a consequence of habitat loss. It is counter-productive to fight one global environmental problem – climate change – and simultaneously exacerbate a second global environmental problem by increasing biodiversity loss. This is, however, a complex trade- off, since climate change is also predicted to have profound impacts on biodiversity (Thomas et al., 2004).
Changes in temperature and rainfall regimes will displace habitats. The predicted rise in temperatures will displace the zone of climate preference for most species polewards or to higher altitudes. It is likely that a significant fraction of species will lose their current habitats completely, and will thus ultimately become extinct unless steps are taken to intervene (Hannah et al., 2002; Thomas et al., 2004). Though biofuels can mitigate climate change impacts in part, this positive impact is likely to be very small compared with the high negative land transformation costs. The
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synergistic impact of both land transformation and climate change will be a double blow to biodiversity, with transformed habitats making it much harder for species to adapt to climate change (Von Maltitz et al., 2010).
Figure 48: Influence of biodiversity on ecosystem services
Source: Von Maltitz et al., 2010: 85)
Two aspects underpin the severity of biodiversity impacts. One is the importance of the habitat for biodiversity protection, and the other is the degree to which the proposed land is degraded or already transformed. A simple matrix (Von Maltitz et al., 2010) illustrates that it is untransformed areas of high biodiversity importance that are likely to have the greatest biodiversity conservation value (see Figure 49, below).
A potential approach in determining the impact on biodiversity due to land-use change is the biodiversity intactness index (BII). The BII is a measure of the change in abundance across a wide range of well-known elements of biodiversity, relative to their levels in a chosen reference case. It is an indicator of the average abundance of a specified set of organisms (or functional groups of organisms) in a given geographical area. The BII is intended to provide a single, integrated measure of biodiversity, and the principles underlying the BII are discussed in Scholes and Biggs (2005) and
insurance value mostly negative feedbacks Provisioning:
food, fibre, water, wood medicines Cultural:
aesthetics tourism spiritualSociety
Individual human wellbeing
Freedom and choice
Security Material needs Health Social relations
market & nonmarket
values
Regulating:
Climate, floods pests & disease
Supporting:
Ecosystem processes, Habitat provision
Response Functional Landscape Diversity Types Diversity
Biodiversity
Non nature-based sources of goods and services actions to protect species and ecosystems ecosystem use decisions167
Biggs (2005). The application of the BII, however, would have gone beyond the scope of this study, and therefore, it has not been included.
Figure 49: Determining conservation importance as a function of both habitat quality and level of degradation of the natural habitat
Source: Von Maltitz et al. (2010: 92)
For this study, another approach aimed at minimising the impact on biodiversity has been applied. In a previous study (refer to Von Doderer, 2009: 9-28), suitable land for biomass production in the CWDM was identified by means GIS. Ecologically sensitive areas, such as protected areas (e.g. nature reserves, national parks), critical biodiversity areas, water catchment areas, waterbodies and wetlands and other sensitive areas from ecological and aesthetical points of view, as identified by an expert group, were amongst other unsuitable land use types excluded.
6.2.2.2 Water balance
Natural capital – air, land, habitats and water – is essential for the natural environment, which performs functions essential for human existence and life on earth (Costanza and Daly, 1992), such as providing biomass. The availability of fresh water is a prerequisite for the growth of biomass. Solar radiation is the principal driving force behind the evaporation of water (Gerbens-Leenes et al., 2009: 1055).
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Degraded or transformed land in high conservation value habitat Conservation value dependent on degree of degradation and possibilities of reclamationBiodiversity importance
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Good condition natural habitat of high
conservation importance Very high biodiversity conservation value
Totally transformed or badly degraded land of an original habitat type of low
conservation importance Very low biodiversity conservation value Good condition natural habitat of low conservation importance
Low overall conservation value – but large scale conversion could alter conservation state
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Various concepts and tools have been developed to determine the water requirements of crops, for instance, CROPWAT, a FAO-developed computer programme for farmers, for irrigation planning and management (FAO, 2011, Allen et al., 1998); or the water footprint (WF) concept introduced by Hoekstra and Hung (2002), who define the WF as the total volume of fresh water used to produce the goods and services related to certain consumption patterns. The WF of a product (commodity, good or service) is defined as the volume of fresh water used for the production of that product at the place where it was actually produced (Hoekstra and Chapagain, 2008). Most of the water used is not contained in the product itself. In general, the actual water content of products is negligible compared with their WF (Gerbens-Leenes et al., 2009).
An assessment has been done by Gerbens-Leenes et al. (2009) of the WF of energy from biomass, and the related consequences of an increasing share of bioenergy in the supply of energy. Various primary energy carriers derived from biomass are expressed as the amount of water consumed to produce a unit of energy (m3/GJ), showing considerable differences among the WFs for specific types of primary bioenergy carriers. The WF depends on the crop type, agricultural production system, and climate. The WF of biomass is 70 to 400 times larger than the WF of other primary energy carriers (excluding hydropower).
Water balance is a location-specific issue, but is likely to be a constraining factor, particularly in the future, when climate change will have a severe impact on agricultural and other activities.
However, although likely to be a constraining factor, the WFs of the bioenergy systems in this study have not been included, since WF is a location-specific issue. Areas not meeting the minimum water requirements were excluded a priori in the land availability assessment by applying the so- called aridity index (Von Doderer, 2009).
In some cases, the introduction of SRC plantations may have a positive effect on the water balance, e.g. when replacing intensive agriculture under irrigation or when establishing SRC plantations on land that is infested with so-called undesired alien invader plants (AIPs).