Author(s): Christina L. Polzot
Published: 2004
Type: M.E.S. Papers/Theses
Climate change is one of the greatest environmental and economic threats facing the world today. Human activities, particularly the burning of fossil fuels and clearing of forests, have increased the level of greenhouse gases - the primary contributors to global warming in the atmosphere. This accumulation is changing the Earth's weather patterns, resulting in higher global temperatures, rising sea levels and a potential shift in the distribution of the world's ecosystems.
There is a growing need to develop strategies that will reduce current levels of greenhouse gases in the atmosphere and curtail future emissions. The Kyoto Protocol represents an international strategy: it establishes emission reduction targets for industrialized countries and incorporates a Clean Development Mechanism for trading carbon credits generated by projects implemented in developing countries.
Tree-based land-use systems, such as the shade-grown coffee agroecosystems of southern Costa Rica, sequester carbon dioxide from the atmosphere and store it in their biomass.
Simultaneously, these agroecosystems provide additional products and services to local residents and reduce pressure on existing forests. Therefore, increasing tree cover in coffee production is a viable option for mitigating climate change that also provides
social, economic and ecological benefits.
The objective of this study is to generate above-ground carbon-stock inventory data for five coffee production systems in southern Costa Rica, which employ various degrees of structural complexity in their shade layer. The sites include coffee grown with poró (Erythrina poeppigiana), guaba (Inga sp.), banana (Musa spp.), eucalyptus (Eucalyptus deglupta) and diversified shade (primarily Terminalia amazonia and Cedrela odorata).
An advanced secondary-forest site at the Los Cusingos Neotropical Bird Sanctuary is used as a control. The carbon-stock of shade trees, coffee bushes and leaf litter is calculated for each site, and the income that could be generated from a one-time payment
for the environmental service provided by shade trees (carbon storage) is estimated.
Results indicate the coffee production system that stores the most amount of carbon per hectare in its above-ground biomass is Diversified Shade (31.6 t C ha-1), employing a
variety of shade-tree species in three distinct layers. Conversely, the Inga sp. system' a shaded monoculture with low structural complexity in its shade layer - stores the least
carbon (11.0 t C ha-1). The carbon-stock of the other systems examined falls within this range and varies according to structural complexity, species composition and management practices.
This study recommends that the shade layer in coffee agroecosystems be made more complex for increased carbon storage and maintenance of biodiversity, as previous papers suggest. In the case of southern Costa Rica, a carbon sequestration project implemented
under the Clean Development Mechanism could provide farmers with an incentive to select management practices that favour higher carbon-stocks and biodiversity. Such an endeavour would have social, economic and environmental benefits and would provide
an example that could be replicated in other small watersheds of Central America.
RESUMEN
El cambio climático es uno de los desafíos más importantes para la comunidad internacional de hoy. Las actividades industriales y la deforestación y quema de los bosques han aumentado la concentración de los gases de invernadero en la atmósfera resultando en un calentamiento de la Tierra, un aumento en los niveles de las aguas
océanicas, y un cambio en la distribución de los ecosistemas.
Es importante formular estrategías que reducen las emisiones de los gases de invernadero y que también disminuyen sus concentraciónes en la atmósfera. Un ejemplo es el Mecanismo de Desarollo en Limpio del Kyoto Protocol, la cuál presenta oportunidades por los países en desarollo de participar en el comercio internacional de carbono.
Los sistemas agroforestales de café de Costa Rica sequestran dióxido de carbono desde la atmósfera y lo almacenan en su biomasa. Estos sistemas también proveen madera, frutas, y otros servicios ambientales a sus proprietarios, mientras que disminuyen la
deforestatición de los bosques. Esta investigación cuantifíca y valora el servicio ambiental almacenamiento de carbono en sistemas agroforestales de café con poró
(Erythrina poeppigiana), guaba (Inga sp.), Musa spp., eucalypto (Eucalyptus deglupta) y
Sombra Diversificada (más de dos especies de árboles de sobra) en el Corredór Biológico Las Nubes/Los Cusingos de Costa Rica. Un sitio de bosque secundario es incluido para comparacíon.
Los resultados indican que el sistema que almacena más carbono es lo de Sombra Diversificada (31.6 t C ha-1) y lo que almacena lo menos es café con guaba (Inga sp.) (11.0 t C ha-1). Se recomienda un aumento en la producción de café con sombra, y en el número y divesidad de árboles de sombra utilizados en los cafetales de la zona. A través del Mecanismo de Desarollo en Limpio, el pago por los servicios ambientales que los sistemas agroforestales proveen podría servir como incentivo para render la producción de café en dicho corredór más sostenible