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Highlights • Linear fragments are native dry forest with potential to provide ecosystem services. • Pollination to soybean was study near and far from linear forest fragments (LFFs). • The open pollination treatment increased pods, seeds and yields by more than 30%. • The proximity to LFFs was not directly related to a larger difference in production. Abstract The delivery of ecosystem services, such as biotic pollination is a benefit that nature provides us. Pollinators increase the quantity, quality and stability of crops for food production. Previous works show that proximity to natural habitats increases crop production through the delivery of pollination services. However, similar researches in subtropical regions is largely lacking. In this study we evaluated the role of linear forest fragments (LFFs) on the provision of biotic pollination service to soybean crops (Glycine max) and explored whether this service changes with increasing distance to LFFs in subtropical dry Chaco (Argentina). In three agricultural farms and testing two soybean varieties, we covered plots of 0.75 m2 with soybean plants and compared them with equally sized open plots. Plots were placed near (60 m) and far (600 m) from LFFs. We found that plants from the open treatment produced 32% more pods, 41% more seeds and had 42% higher yield (kg/ha) than plants from the covered plots. The difference between open and covered plots in seeds and yield did not change significantly with the distance to LFFs, but the number of pods, contrary to what we expected, was higher far from LFFs. Our findings highlight the possible impact of pollinators on soybean yield in both varieties tested here; but the proximity to LFFs was not directly related to a larger difference in production. Observed patterns are explained by edge effects and competition between soybean plants and trees near LFFs, combined with an underestimation of the distance from the natural hives to which honeybees can efficiently exploit the crops. In this subtropical region, soybean expansion is the most important driver of land cover change and this study represents a first step towards a better understanding of the functioning of these remnants of natural areas within the agricultural land in the region of dry Chaco forests. [ABSTRACT FROM AUTHOR]

Abstract: Invasions of exotic tree species can cause profound changes in community composition and structure, and may even cause legacy effect on nutrient cycling via litter production. In this study, we compared leaf litter decomposition of two invasive exotic trees (Ligustrum lucidum and Morus sp.) and two dominant native trees (Cinnamomum porphyria and Cupania vernalis) in native and invaded (Ligustrum-dominated) forest stands in NW Argentina. We measured leaf attributes and environmental characteristics in invaded and native stands to isolate the effects of litter quality and habitat characteristics. Species differed in their decomposition rates and, as predicted by the different species colonization status (pioneer vs. late successional), exotic species decayed more rapidly than native ones. Invasion by L. lucidum modified environmental attributes by reducing soil humidity. Decomposition constants (k) tended to be slightly lower (−5%) for all species in invaded stands. High SLA, low tensile strength, and low C:N of Morus sp. distinguish this species from the native ones and explain its higher decomposition rate. Contrary to our expectations, L. lucidum leaf attributes were similar to those of native species. Decomposition rates also differed between the two exotic species (35% higher in Morus sp.), presumably due to leaf attributes and colonization status. Given the high decomposition rate of L. lucidum litter (more than 6 times that of natives) we expect an acceleration of nutrient circulation at ecosystem level in Ligustrum-dominated stands. This may occur in spite of the modified environmental conditions that are associated with L. lucidum invasion. [Copyright &y& Elsevier]

Abstract: Grazing and fire have been the most common disturbances in many grasslands ecosystems for many centuries. However, some mountain regions are currently experiencing a decrease in land use, and therefore in frequency or intensity of these disturbances. In this study, we evaluated how fire and grazing affect vegetation structure in mountain grasslands of NW Argentina. We hypothesized that they would have differential effects on plant species richness, vegetation composition and aerial biomass dynamics, predicting that fire would have a stronger effect on these variables than grazing. We tested this hypothesis by performing a controlled field experiment in which we manipulated fire and compared grazed plots with ungrazed exclosures, simulating current (high frequent fires and low livestock load) and future (fire suppression and grazing exclosure) scenarios. We recorded total of 90 species with 40 shared among all treatments. Tussock grasses (Elionurus muticus), followed by three shrubs represented the main contribution to live biomass in all treatments. Species richness, equitativity and diversity were higher in burned plots. Multivariate ordination indicated that burning is more important than grazing in determining plot to plot similarity in species composition. Burning reduced total aerial biomass, standing dead biomass and litter, as well as live biomass, that was also reduced by grazing. Burning also reduced standing dead biomass and litter proportions, but increased live biomass contribution, showing a more evident effect within the grazed plots. Burning, seasonality and growing season had significant effects on the relative contribution of all biomass categories. Biomass consumption showed a strong seasonality, being significantly higher in January of both growing seasons, and it was not affected by burning. We conclude that under the current fire and grazing scenario, fire plays a more important role than grazing in shaping these grasslands dynamics. [Copyright &y& Elsevier]