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Category: 2003

Integrity and Isolation of Costa Rica’s National Parks and Biological Reserves: examining the dynamics of land-cover change

G. Arturo Sanchez-Azofeifa, Gretchen C. Daily, Alexander Pfaff, Christopher Busch
Biological Conservation 109 (2003) 123–135

PDF link iconThe transformation and degradation of tropical forest is thought to be the primary driving force in the loss of biodiversity worldwide. Developing countries are trying to counter act this massive lost of biodiversity by implementing national parks and biological reserves. Costa Rica is no exception to this rule. National development strategies in Costa Rica, since the early 1970s, have involved the creation of several National Parks and Biological Reserves. This has led to monitoring the integrity of and interactions between these protected areas. Key questions include: ‘‘Are these areas’ boundaries respected?’’; ‘‘Do they create a functioning network?’’; and ‘‘Are they effective conservation tools?’’. This paper quantifies deforestation and secondary growth trends within and around protected areas between 1960 and 1997. We find that inside of national parks and biological reserves, deforestation rates were negligible. For areas outside of National Parks and Biological reserves we report that for 1-km buffer zones around such protected areas, there is a net forest gain for the 1987/1997 time period. Thus, it appears that to this point the boundaries of protected areas are respected. However, in the 10-km buffer zones we find significant forest loss for all study periods. This suggests that increasing isolation of protected areas may prevent them from functioning as an effective network.


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Carbon dynamics and land-use choices: building a regional-scale, multidisciplinary model

Suzi Kerr, Shuguang Liu, Alexander Pfaff, R. Flint Hughes
Journal of Environmental Management 69 (2003) 25–37

PDF link iconPolicy enabling tropical forests to approach their potential contribution to global-climate-change mitigation requires forecasts of land use and carbon storage on a large scale over long periods. In this paper, we present an integrated modeling methodology that addresses these needs. We model the dynamics of the human land-use system and of C pools contained in each ecosystem, as well as their interactions. The model is national scale, and is currently applied in a preliminary way to Costa Rica using data spanning a period of over 50 years. It combines an ecological process model, parameterized using field and other data, with an economic model, estimated using historical data to ensure a close link to actual behavior. These two models are linked so that ecological conditions affect land-use choices and vice versa. The integrated model predicts land use and its consequences for C storage for policy scenarios. These predictions can be used to create baselines, reward sequestration, and estimate the value in both environmental and economic terms of including C sequestration in tropical forests as part of the efforts to mitigate global climate change. The model can also be used to assess the benefits from costly activities to increase accuracy and thus reduce errors and their societal costs.


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Fuel-choice and indoor air quality: a household-level perspective on economic growth and the environment

Shubham Chaudhuri, Alexander Pfaff
Working paper, Columbia University SIPA

PDF link iconThe fuel-use decisions of households in developing economies, because they directly influence the level of indoor air quality that these households enjoy (with its attendant health effects), provide a natural arena for empirically assessing latent preferences towards the environment and how these evolve with increases in income. Such an assessment is critical for a better understanding of the likely effects of aggregate economic growth on the environment. Using household data from Pakistan we estimate Engel curves for traditional (dirty) and modern (clean) fuels. Our results provide empirical support for a household production framework in which non-monotonic environmental Engel curves can arise quite naturally. Under plausible assumptions about the emissions implied by fuel use, our estimates yield an inverted-U relationship between indoor air pollution and income, mirroring the environmental Kuznets curves that have been documented using aggregate data. We then demonstrate, through a simple voting model, that this household-choice framework can generate aggregate EKCs even in a multi-agent setting with heterogeneous households and purely external environmental effects.

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