Improving degraded pastures in Central America
A large collaborative research project aimed at improving the forage value of degraded pastures in Central America is now coming to an end. But the research continues, due to the project’s interesting findings and methodology.
Ida Søraunet Wangberg
A large part of Central America consists of silvopastoral landscape, a mosaic of pasture lands with various degrees of tree and forest cover. Commonly, the landscape derives from the clearing of seasonally dry forests, a type which is among the most endangered globally, since clearing and other human activities have impacted these forests much earlier than other tropical forests. The massive conversion of forests to pasture have not been followed by the sustainable management of pasture, leaving 50 - 80% of them degraded.
Wide collaboration network
Graciela Rusch, researcher at the Norwegian Institute for Nature Research (NINA) in Trondheim, is the coordinator of the multidisciplinary research project “Improvement of the forage value of degraded pastures in Central America: local knowledge, answers to grazing, and diversity of species and landscapes”. The research has been conducted in the central zones of Nicaragua and in El Petén in Guatemala, and the project is now in its finalizing stage.
- An important scientific aim of our project was to understand the composition of these grazing grounds with predominantly spontaneous vegetation that established after the clearing. We also wanted to look at how cattle uses the natural pastures, and finally what important factors are guiding the management decisions made by the farmers about these socio-ecological systems, explains Rusch, who holds a PhD in ecological botany from the University of Uppsala in Sweden.
The project she is coordinating is more often referred to as “Proyecto Pasturas de Centroamérica” (PACA). It started in 2003 as a collaborative initiative between NINA and the Centro de Agronómico Tropical de Investigación y Enseñanza (CATIE), a regional academic organization with support from the governments of most of the Central American and some South American countries. The Centre for Development and the Environment (SUM) at the University of Oslo joined in as a partner, and finally the project expanded rapidly to a wide collaborative network including the Norwegian University of Science and Technology (NTNU) and the Norwegian University of Life Sciences (UMB). The Norwegian Agency for Development Cooperation (Norad) provided substantial financial support.
Emphasizing diverse ecological systems
- The aim of the project was to strengthen the research capacity and increase the knowledge about the ecology of grazing in silvopastoral systems in Central America and to gain a better understanding about how they are managed. Pastures, trees and cattle interact through ecological functions such as feed production, shading, grazing selectivity and trampling, and the farmer makes choices that determine to a large extent how these components interact, says the researcher, whose own research has been focusing primarily on grassland vegetation and the effects diversity has on seasonal stability of pasture production.
-We hypothesized that more functionally diverse systems would have a more homogeneous production throughout the year and cope better with the droughts that occur during the dry season, compared to pastures with a predominance of a single species. A PhD student, Sonia Ospina, has worked on this, and she will complete her thesis in the Norwegian spring semester of 2010, says Rusch.
The project coordinator further emphasizes the valuable contributions of Norwegian and Central American PhD and MSc students, whose training has been part of the project.
- We studied which silvopastoral functions the farmers value and which factors underlie the adoption of certain silvopastoral practices, including the choice of tree species and the use of practices such as burning. Various MSc students studied how the cattle graze and which components of the pasture they select, comparing pastures in the highlands and lowlands, and preferences during the dry and the wet season. Another MSc study dealt with the effect of cattle on tree regeneration. This is an important question, because trampling and browsing (feeding on trees and bushes) directly affect the establishment of small tree plants. Also fires and clearing affect regeneration of trees. The trees that occur in the silvopastoral landscape are remnants of the forest that once covered the area, and regeneration is extremely important considering the fact that this type of forest is endangered.
- The methodology of emphasizing productivity is important, claims Rusch, explaining that it is a common mistake to confuse productivity, the accumulation of biomass during a certain period of time, with “standing bio mass”, meaning how much bio mass exists in a certain area. According to the ecologist, productivity is the only correct way of measuring how much feed there is actually available for the animals. Productivity in this sense means how much vegetation grows during a certain period of time.
- Collecting data on productivity is very time consuming, you have to do many cuttings and keep the livestock away using cages or fences. We did this in various investigations, and the results are soon to be published in a PhD dissertation and a MSc thesis, Rusch announces.
The research continues
Although this project is coming to an end with the two last PhD students defending their dissertations at the turn of this year, the collaboration continues, and with it the focus on the issue of silvopastoral systems in Central America. Now, the focus will be on Nicaragua in two ongoing projects which receive funding from the Research Council of Norway (RCN). Both projects build on the existing network of partners.
-The PACA project has clearly contributed to filling a knowledge gap concerning the management of the pastures of Central America, but the methodologies used in the project can also easily be adopted in studying similar landscapes in other regions. This will be done in a third project on silvopastoral systems, which receives financial support from the EU and was initiated in May 2009, says Rusch.
In addition to Nicaragua, this project looks at West African silvopastoral systems in Mali and Senegal. NINA is again the coordinating institution, and the other partners are CATIE, Centre de coopération internationale en recherche agronomique pour le développement (CIRAD, France), Consejo Superior de Investigaciones Científicas (CSIC, Spain), the University of Wageningen (the Netherlands), Institut Senegalais de Reserches Agricoles (ISRA) and Institut de Economie Rurale (IER) in Mali.
-Our interest is again how we can characterize silvopastoral systems with the functional aspects of the trees as a starting point. We want to test our hypotheses and see if systems with higher functional diversity can fill more ecological functions and be capable to deliver more services to the cattle farmers. On this basis we want to design multifunctional silvopastoral systems that function better than the existing ones, both when it comes to ecological aspects and production, concludes Rusch, who is coordinating all three projects.
Most of the results from the PACA project are published in a special issue of the journal “Agroforestería en las Américas”, which can be found here: