CARLOS ALBERTO RUIZ GARVIA, HOLM TIESSEN, MARTIN WORBES
Georg-August-Universität Göttingen, Institute of Agronomy in the Tropics and Subtropics, Germany
Forest fallow in large areas of Semiarid Americas plays a vital role in the maintenance of land quality and are also important for the community. The total benefits of ecosystem services provided by forest fallows and the potential for forest production have not been evaluated, largely because forest productivity under secondary land cover has rarely been measured with an eye to marketable products. We here explored options for improved landuse management in secondary forest in Northern Yucatan, Mexico. We measured nutrient budgets in soils and vegetation and use tree-ring analysis to predict tree productivity in fallow vegetation of different succession states. Cross dating techniques were used to identify correlation between tree growth and climatic patterns. Furthermore, trials were established to identify limiting factor in soils.
Overall fertility may be lower in young secondary forest. Unlike the other indices of fertility, K levels were significantly higher in young forest which may indicate translocation functions of plants when K becomes limiting factor. This result is consistent with more rapid turnover of organic matter or greater amounts of material cycling through the forest floor litter layer.
Tree species of young secondary forest showed the higher mean annual diameter increment than those from old secondary forest. Tree ring analysis for core-samples of Cordia dodecandra and Piscidia piscipula showed a positive relation with the annual rainfall and total precipitation in the rainy period. In Piscidia piscipula the mean ring-widths vary between 0.8 mm per year whereas in Cordia alliodora 0.6 mm per year. Tree species of young secondary forest show higher annual increment with 1.2 mm per year than old secondary forest.
Keywords: Landuse change, secondary forest, soil quality, tree ring analysis