毕业论文英文 Impacts Of Biofuel Expansion In Biodiversity Hotspots
X.3.1. Degraded lands
Clearly, the obvious solution is to avoid planting biofuel feedstocks on native natural habitats (IATP 2008). The replacement of biodiverse habitats with monoculture plantations is without a doubt the greatest threat to biodiversity in these hotspots. Moreover, as many of these hotspots contain high levels of endemic flora and fauna, the loss of these habitats would result in global extinctions of numerous species (Myers et al. 2000). The removal of critical ecosystems for biofuel production negates any benefits accrued from the use of biofuels over fossil fuels (Gibbs et al. 2008). Some researchers have argued for the use of �degraded lands� for biofuel cultivation. However, this proposal is not as straightforward as it seems. Should the definition of �degraded� be stretched to include secondary logged forests, then biodiversity losses will continue as such forests still preserve a significant portion of primary forest biodiversity (Dunn 2004; Barlow et al. 2007; Koh & Wilcove 2008). In some cases, degraded lands have been shown to be utilized by high conservation value species like the Sumatran tiger and the value of their biodiversity cannot be judged simply based on the vegetation structure and characteristic of the landscape (Maddox 2007). Significant amounts of fertilizers and weed control are also required to convert alang-alang grasslands into oil palm plantations (Fairhurst and McLaughlin 2009) and insecure land tenure regarding degraded lands pose big risks to any biofuel feedstock producing company investing in plantation development (Cotula et al. 2008). Degraded lands can also be open to other land uses such as restoration ecology, cattle ranching, settlements and urbanization, hence strategies to expand biofuel production into degraded lands must be approached with caution.
X.3.2. PES and REDD
Apart from their biodiversity values, it is imperative to recognize the ecosystem services natural habitats provide including genetic diversity, carbon sequestration, water cycling and purification, climate regulation and many other non-timber products which are not found elsewhere (Constanza et al. 1997). The establishment and enforcement of protected areas in biodiversity hotspots remains a top strategic priority for protecting biodiversity, but these legislative tools could be supplemented with innovative schemes, such as Payment for Ecosystem Services (PES) or Reducing Emissions from Deforestation and Degradation (REDD), which create financial incentives to divert agricultural expansion away from forests and onto pre-existing croplands or degraded lands. The question which follows then is whether such incentives are sufficient to counter strong market forces that favour natural habitat conversion. Recent REDD scheme partnerships between non-governmental organizations and private companies (Fisher 2009) are positive steps towards greater collaboration and engagement of various stakeholders towards conserving forests in biodiversity hotspots. However, few studies have compared the feasibility of such schemes against current market prices for biofuel feedstocks. Butler et al. (2009) compared the profitability of converting forests into oil palm plantations against conserving forests for an REDD scheme. Under current voluntary carbon markets, conversion of forest into oil palm (yielding net present values of US$3835-$9630) will be more profitable to landowners than preserving it for carbon credits (US$614-$994). However, should REDD become a legitimate emissions reduction activity under the second commitment period of the Kyoto Protocol (2013-17), carbon credits traded in Kyoto-compliance markets have a fighting chance to compete with oil palm agriculture or other similarly profitable human activity as an economically attractive land-use option. Similar economic evaluations of comparing the value of non-forest biodiverse habitats like the Cerrado to soybean and sugarcane production in Brazil can also be carried out to determine the competition of various land uses based on monetary values. A recent study by Igari et al. (2009) calculated an annual profitability of US$134/ha/year and US$149/ha/year for sugarcane and soybean crop respectively growing near the Cerrado region in Sao Paulo State, Brazil. Opportunity costs to set aside the Cerrado for preservation were much higher compared to PES values of US$27 and US$42 per ha paid to landowners in Mexico and Costa Rica respectively (Munoz-Pina et al. 2008; Barton et al. 2009) and only slightly comparable, US$111 per ha, with the average annual value paid by USDA Conservation Reserve Programme in the United States (USDA 2006; Baylis et al. 2008). Considerable amount of research is currently underway to use REDD as a tool against natural habitat conversion by other land uses (Mongabay 2010). However, for natural habitats which are already slated for land use conversion, complete avoidance is not a realistic option and strategies to mitigate biodiversity impacts will have to be formulated.
X.3.3. Improve management practices
To partially reconcile biofuel expansion with biodiversity conservation, a set of compromises regarding biodiversity loss and a great deal of collaboration with biofuel producers will be required. It will be imperative for conservation groups to engage with biofuel producers of various levels � from small farmers to large private companies, to help producers and growers recognize the value and importance of biodiversity in the unique habitats where they grow their biofuel crops. As soybean and sugarcane are annual crops, little can be done to preserve biodiversity within the agricultural landscape when great disturbances to the landscape occur during harvest seasons. Fewer disturbances occur in oil palm plantations which are perennial crops that last for a period of 25 to 30 years. In these artificial habitats, (Koh 2008a) demonstrated that various local vegetation characteristics such as percentage ground cover of weeds, epiphyte prevalence and presence of leguminous crops can help enhance native bird and butterfly species richness. On a landscape level, the percentage of natural forest cover was able to explain 1.2-12.9% of variation in butterfly species richness and 0.6-53.3% of variation in bird species richness. Adoption of such measures is not just important to make oil palm plantations more hospitable for native biodiversity. Bird-exclusion experiments in oil palm plantations have shown a significant increase in herbivory damage by herbivorous insects, providing an economic justification for conserving remnant natural habitats for this natural pest control service (Koh 2008b). Many oil palm plantations have also included integrated pest management systems which favour the use of non-chemical pest control methods such as the establishment of �beneficial plants� (e.g. Euphorbia heterophylla) to attract insect predators and parasitoids of oil palm pests (e.g. the wasp Dolichogenidea metesae [Basri et al. 1995; Corley & Tinker 2003]). Other means of mitigating the impacts on biodiversity loss within the oil palm plantation landscape include the formation of riparian buffer zones to reduce water pollution, preservation of high conservation value (HCV) forests, formation of wildlife buffer zones to �soften� the edge between plantations and natural forests and the creation of habitat corridors to link remnant forest patches together (Maddox 2007; Fitzherbert et al. 2008). Even with the employment of all these responsible management practices, oil palm and other biofuel plantations will still have a considerable residual impact on the environment. In such cases, biodiversity offsets which is the calculation of the residual impact and paying off by conserving another natural habitat, have been proposed to ensure full compensation to the environmental damage incurred by the plantation (Maddox 2007).
