Carlos Ovalle

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Growth rate, resource partitioning, and several biological traits related to biological N2 fixation for six native or non-native tree species were compared using 15N isotope dilution techniques. The trees were field grown for six years in a semiarid mediterranean-climate region with five to six months a year of absolute drought. Trees were tested as(More)
Burr medic (Medicago polymorpha) is distributed in a wide range of bioclimatic and edaphic conditions throughout the mediterranean-climate region of Chile. Previous studies on populations of M. polymorpha collected along this gradient revealed a remarkable ecotypic differentiation in many adaptive traits. Random amplified polymorphic DNA (RAPD) was used to(More)
Cover cropping is increasingly being used as a form of sustainable soil management in grapevine (Vitis vinifera L.) production. The objective of the current study was to determine the effect of a legume cover crop on a set of growth and production variables of a vineyard, and to quantify the relative importance of legume nitrogen (N) as a source of N for(More)
Burr Medic (Medicago polymorpha) is awidespread, polymorphic annual legume of Mediterranean origin, and as aself-reseeding, highly effective nitrogen fixer it has important value invarious dryland farming systems. In central Chile, it is naturalized along a1000 km long environmental gradient, from an arid zone(29°–31° S) to a perhumid one(37°–38°24' S).(More)
In this second article of a series analysing ecotypic differentiation ofthe Burr Medic (Medicago polymorpha L.),occurring along a 1000 km natural aridity gradient in centralChile, we report variations in growth potential at low temperature in relationto phenology and latitude of collecting site. In two experiments conducted inoutdoor nursey trials at(More)
Our system used Apache’s Lucene library [1] for its core indexing and retrieval functions. We also relied on language modeling extensions to Lucene provided by the Informatics Institute at the University of Amsterdam [2]. However, We altered these libraries to enable our IR approach. In particular, our results rely on a variant of the Kullback-Leibler (KL)(More)
An approach to derive relationships for defining land degradation and desertification risk and developing appropriate tools for assessing the effectiveness of the various land management practices using indicators is presented in the present paper. In order to investigate which indicators are most effective in assessing the level of desertification risk, a(More)
The Central Valley of Chile is largely occupied by a pseudo-savanna called ‘espinal’ consisting of a single dominant tree species, Acacia caven (Mol.) Mol. (Leguminosae), and some 215 annuals, most of which were inadvertently introduced from the Mediterranean Basin. The probable origin and current distribution of the ‘espino’ (Acacia caven) and the(More)
Indicator-based approaches are often used to monitor land degradation and desertification from the global to the very local scale. However, there is still little agreement on which indicators may best reflect both status and trends of these phenomena. In this study, various processes of land degradation and desertification have been analyzed in 17 study(More)