Go to New Research Headlines

January 2008

The exotic grass, Saccharum spontaneum, has invaded abandoned agricultural lands in the Panama Canal Watershed for decades. The grass aggressively competes with regenerating seedlings of tree species preventing natural forest regeneration. A recent study tested the effects of shading on the growth of the grass using artificial shading conditions. The results showed that there were significant differences between full sunlight and light intensities of 5%, 15% and 25%. The biomass of S. spontaneum was significantly less in lower light conditions than in full sunlight. The study demonstrates that shading is an effective method for controlling S. spontaneum. The result can be applied to developing reforestation strategies for abandoned lands occupied by S. spontaneum.

For more information, contact Professor Florencia Montagnini: (203) 436 4221; florencia.montagnini@yale.edu

References:
Kim, T. J., F. Montagnini, D. Dent. 2008. Rehabilitating abandoned pastures in Panama: control of the invasive exotic grass, Saccharum spontaneum (L.), using artificial shade treatments. Journal of Sustainable Forestry 26(3): In Press.

Kim, T. J., F. Montagnini, N. Cedeño, D. Dent and E. Mariscal. 2006. Investigation of shading as a method for controlling wild sugarcane on abandoned lands (Panama). Ecological Restoration 24(3): 203-204.

January 2008

Pastures and agrosilvopastoral land represent 77% of the total agricultural land in the Neotropics, mostly on poor acid soils. Conversion of forests to crops and pastures has been the most important land–use change in the Neotropics during the second half of the 20th century. About 30% of these pastures are degraded as a result of stocking levels being higher than carrying capacity. Abandoned pastures can remain in a state of arrested succession due to a number of factors that delay or impede their recovery. However, there are strategies that can be used to increase sustainability and avoid degradation. When pastures have been abandoned due to low productivity, there are also strategies that can be used to restore the forest and its plant and animal diversity. Factors involved in pasture degradation, and experiences used to increase pasture sustainability and restore degraded pastures in the Neotropics are presented in a book chapter recently published by Professor Montagnini.

For more information, contact Professor Florencia Montagnini: (203) 436 4221; florencia.montagnini@yale.edu

References:
Montagnini, F. 2008. Management for sustainability and restoration of degraded pastures in the Neotropics. Pp. 265-295 In: Myster, R. Post-agricultural succession in the Neotropics. Springer, New York.

Montagnini, F. and Jordan, C. F. 2005. Tropical Forest Ecology. The Basis for Conservation and Management. Springer-Verlag, Berlin-New York. 295 pp.

September 2007

Lack of seed dispersal is an important obstacle to natural regeneration of degraded pastures. Research on seed rain and seed dispersal agents in pure and mixed plantations of native trees and abandoned pastures at La Selva Biological Station, Costa Rica, revealed that tree plantations can facilitate secondary forest succession by attracting seed dispersal agents from nearby forests. Plantations of Balizia elegans, Dipteyx panamensis, and Jacaranda copaia had the greatest seed abundance; while non-planted abandoned pasture controls had the least amounts of seeds. Plantations of J. copaia and Hyeronima alchorneoides had the greatest seed species richness, while the lowest was found in the controls. The control plots had more seeds dispersed by wind, while in the plantations the most important dispersal agents were birds and mammals. The study concluded that plantations of native trees are effective in attracting seed dispersal agents and thus facilitating regeneration of degraded pasturelands in the region. For more information, contact Professor Florencia Montagnini: (203) 436 4221; florencia.montagnini@yale.ed

References:
Orozco Zamora, C. and Montagnini, F. 2007. Seed rain and seed dispersal agents in pure and mixed plantations of native trees and abandoned pastures at La Selva Biological Station, Costa Rica. Restoration Ecology 15(3): 453-461.

Cusack, D. and F. Montagnini. 2004. The Role of Native Species Plantations in Recovery of Understory Diversity in Degraded Pasturelands of Costa Rica. Forest Ecology and Management 188: 1-15.

2006

The region of Mesoamerica is densely populated and suffers from poverty and malnutrition both in urban and rural areas. Homegardens provide the household with a basic food source as well as high value products to generate cash. Mesoamerican homegardens are quite diverse in their vertical and horizontal structure and species composition. Exotic and native plants are used, with emphasis on fruit trees. Many indigenous communities, descendants of the ancient Maya, still manage homegardens using techniques that include residue management and ash deposition, thus enhancing nutrient recycling and conservation. Carbon sequestration may be important due to the efficient capture of solar radiation in the multi-layered homegardens, although its global or regional importance is minimal due to their relatively small area.

References:
Montagnini, F. 2006 "Homegardens of Mesoamerica: Biodiversity, food security, and nutrient management." In: Tropical Homegardens: A Time-Tested Example of Sustainable Agroforestry. Advances in Agroforestry 3, B. M. Kumar and P. K. R. Nair (eds). Springer Science, Dordrecht, The Netherlands. Chapter 5, pp. 61-84.

Montagnini, F. and P. K. Nair. 2004. Carbon Sequestration: An under-exploited environmental benefit of agroforestry systems. Agroforestry Systems 61: 281-295.