The scientific community suffers today from a great loss. The world-recognized Dutch scientist, Emeritus Professor Leendert (Len) 't Mannetje, from Wageningen University and Research Centre (WUR), PhD in Grassland Science, died February 18, 2008, at the age of 74 in Wageningen, only a few weeks after the presentation of his latest book “Carbon Sequestration in Tropical Grassland Ecosystems” on January, 25, 2008 at an important Book Launching seminar organized by FAO in Rome.

Immediately after his MSc graduation at WUR in 1958, Len ‘t Mannetje left The Netherlands for Australia. He became a researcher and defended his PhD dissertation in Brisbane on the taxonomy of Stylosanthes (PhD Dissertation reference: Mannetje, L. 't. (1966). Taxonomic studies within the genus Stylosanthes Sw.(Fabaceae). PhD Thesis, University of Queensland). Subsequently, he accepted the position of Senior researcher in CSIRO, widened his scientific experience in, among others, Malaysia, and became a highly respected member of editorial boards of scientific journals, committees and directorates, mostly in the position of Chairman. In 1981, the family decided to return to the Netherlands, where he was appointed Professor and Director of the Department of Agricultural Plant Production and Grassland Science at WUR. After his retirement in 1995, Prof. 't Mannetje continued traveling around the world, guiding many PhD students, and giving seminars and lectures. In The Netherlands, he had a great influence in scientific boards and committees. Grasslands and rangelands --an important land use, and improved and sustainable exploitation-- were Prof. 't Mannetje's true passion. Due to his work, the use of legumes in grasslands has strongly increased worldwide. He is the author of over 100 refereed papers and book chapters, and the editor of four books.

During his highly productive life Professor 't Mannetje enhanced scientific knowledge of grasslands, both temperate and tropical, and conducted applied research aiming at offering feasible solutions for increased food supply and poverty reduction in tropical developing countries. His research, focused on the agronomy and implementation of productive, sustainable and well-managed grassland systems (grass-alone, grass-legume associations, silvo-pastoral and agroforestry systems) helped increase land productivity, farmer’s socio-economic benefit and sustainable development of pasturelands, particularly in Australia and tropical America. His last book “Carbon Sequestration in Tropical Grassland Ecosystems”, edited by L. ‘t Mannetje, M. C. Amézquita, P. Buurman and M. Ibrahim, published by Wageningen Academic Publishers (2008), summarizes research results of a 5-year, international and multi-institutional project studying the C sequestration capacity of pasture, agropastoral, and silvopastoral systems in ecosystems of tropical America vulnerable to Climate Change. From 2001 to 2007 he contributed as external Consultant to this project, whose scientific director, Dr. María Cristina Amézquita, is one of his former PhD students in WUR.

Past January 25, 2008, FAO in its main office in Rome, organised an important seminar to celebrate the official launching of the scientific publication entitled “Carbon Sequestration in Tropical Grassland Ecosystems”, edited by Leendert ‘tMannetje, Maria Cristina Amézquita, Peter Buurman and Muhammad Ibrahim, published by Wageningen Academic Publishers, The Netherlands. The publication reports on research into carbon (C) storage and sequestration in pasture and silvopastoral systems, with reference to native forest and degraded land, in four ecosystems in tropical America vulnerable to Climate Change: Andean Hillsides and Amazonian humid tropical forest, Colombia; and humid and sub-humid tropical forest, Costa Rica. Research was carried-out by the 5-year project (2001-2006) “Research Network for the Evaluation of Carbon Sequestration Capacity of Pasture, Agropastoral and Silvopastoral Systems in Ecosystems of Tropical America” financed by The Netherlands Cooperation and implemented by research teams of two Colombian institutions (CIPAV and University of Amazonia) and three international centers (CIAT, CATIE, and Wageningen University and Research Centre). The project responds to the UNFCCC and Kyoto Protocol. The most important conclusion is: sustainable, well-managed and productive pasture and silvopastoral systems have the capacity to sequester significant amounts of C in the soil comparable to those of native forest, and to increase production, income, and sources of labor at the same time when directed to recuperate already deforested, degraded pasturelands. Research results position these systems as environmentally and economically beneficial alternatives to recover degraded areas in ecosystems vulnerable to Climate Change.

The largest proportion of the accumulated C in all land use systems studied was in the soil (i.e., more than 96% in pastoral systems, around 90% in silvopastoral systems, and between 58 and 76% in native forests depending on years under non-intervention). Another very interesting finding of this research is the following: in terms of C accumulation in the soil, improved pastoral and silvopastoral systems showed levels similar --and sometimes higher-- to those from native forests. Among the land use types studied, improved pastures (whether in monoculture or in association with leguminous species) presented the highest potential to enhance C accumulation. Depending on climate and soil conditions, these systems, when long-established (10-20 years under commercial production) showed annual rates of soil C sequestration ranging between 2.6 and 2.8 ton/ha/year at 1m of soil depth. When newly-established on degraded soils, improved pastoral and silvopastoral systems showed soil C sequestration rates in a 4-year experimental period of 1.8 to 7.7 t/ha/year/1m depending on the ecosystem.

These findings clearly indicate that improved and well-managed pastoral and silvopastoral systems must be considered as a viable strategy for C sequestration in already deforested, degraded pasturelands of Tropical America.