No abstract

ABSTRACT. Biodiversity conservation through land-use systems on private land is becoming a pressing environmental policy issue. Agroforestry, such as shade-coffee production, contributes to biodiversity conservation. However, falling coffee prices force many coffee growers to convert their sites into economically more attractive land uses. We performed an economic evaluation of coffee pollination by bees in two distinct tropical regions: an area of low human impact with forests neighboring agroforestry in Indonesia and an area of high human impact with little remaining forest in Ecuador. We evaluated bee pollination for different forest-destruction scenarios, where coffee yields depend on forests to provide nesting sites for bees. We used two novel approaches. First, we examined how coffee net revenues depend on the pollination services of adjacent forests by considering berry weight in addition to fruit set, thereby providing a comprehensive evaluation. Second, we determined the net welfare effects of land-use changes, including the fact that former forestland is normally used for alternative crops. In both regions, crop revenues exceeded coffee pollination values, generating incentives to convert forests, even if owners would be compensated for pollination services. The promotion of certified "biodiversity-friendly" coffee is a feasible option to maintain shade-coffee systems. This is of special importance in high-impact areas where only small forest fragments remain. We conclude that a comprehensive economic analysis is necessary to adequately evaluate rainforest preservation for the enhancement of ecosystem services, such as pollination.

Converting degraded grazing lands into exclosures is one option to restore soil nutrients and to sequester carbon from the atmosphere. We estimate the economic value of such a conversion and assess the perception of local communities concerning exclosures in the highlands of Tigray, Ethiopia. Our research combines a soil and vegetation study with a socio-economic survey, and a financial analysis. Over a period of 30 years, sequestered carbon dioxide was 246 Mg ha À1, total soil nitrogen increased by 7Á9 Mg ha À1 and additional available phosphorous stocks amounted to 40 kg ha À1. The Net Present Value of exclosure's ecosystem services under consideration was about 28 per cent (837 US $) higher than alternative wheat production. Carbon revenues alone added up to only about 44 per cent of the net revenues of wheat production. This indicates that (i) carbon market revenues only, would not generate sufficient incentives to establish additional exclosures, and (ii) if all benefits are taken into account and financially rewarded, exclosures are competitive to alternatives land uses. We also identified substantial opportunities to mobilize the local communities in efforts to establish exclosures, given that more than 75 per cent had a positive view on exclosures effectiveness to restore degraded soils and vegetation. We conclude that a comprehensive analysis is necessary to consider the ecological as well as economic and social impacts of exclosures. Our findings are important information for local decision makers and may provide incentives for the establishment of further exclosures in the Northern Highlands of Ethiopia, thereby contributing to a sustainable local development process.

No abstract

Conservation payments can be used to preserve forest and agroforest systems. To explain landowners' land-use decisions and determine appropriate conservation payments, it is necessary to focus on revenue risk. Marginal conditional stochastic dominance rules are used to derive conditions for determining the conservation payments required to guarantee that the environmentally preferred land use dominates. An empirical application to shaded coffee protection in the biologically important Chocó region of West Ecuador shows that conservation payments required for preserving shaded coffee areas are much higher than those calculated under risk-neutral assumptions. Further, the extant distribution of land has strong impacts on the required payments.

No abstract

Fruit set and quality of highland coffee (Coffea arabica) have been experimentally shown to be higher with bee-mediated or manual pollen supplementation than with autonomous self-pollination. Based on extrapolation from these small-scale experiments, very substantial monetary values for the pollination service have recently been suggested. However, previous research has not included direct measurement of coffee yield at a farm level in relation to pollinator activity, testing if pollinators are not only limiting fruit set and quality, but also coffee yield and farm profit. The extrapolations from smallscale experiments may be subject to error, because resource reallocation during fruit development, associated with enhanced pollination, was neglected, and many studies were restricted to a single coffee farm, limiting the validity of extrapolation. Here, we investigate the relationship between coffee yield and the community of coffee flower-visiting bees on 21 farms in Ecuador, where coffee is grown under tree shade. Our data show, for the first time on a farm-scale, that coffee yield was positively related to the density of non-managed, social flower-visiting bees per coffee shrub, but not to the number of inflorescences per shrub. Our data revealed that a fourfold increase in bee density was associated with an 80% increase in yield and an 800% increase in net revenues. Consequently, in our study higher yield associated with increased pollination generated higher revenues per hectare, so that farm profit was higher when bees were abundant.

No abstract