Actualización del inventario y situación técnico-legal de los derechos y operaciones mineras en la Cuenca Binacional del río Suches (Perú – Bolivia)

Ante la contaminación ambiental provocada por la actividad minera informal que ocurre en la cuenca del río Suches, y el permanente incremento de las operaciones desde el año 2006, se plantea la necesidad de implementar mecanismos necesarios y conducentes a la prevención y mitigación de esta contaminación; es así, que una vez tomado conocimiento de esta situación se conformaron comisiones técnicas de la República del Perú, por encargo del Ministerio de Energía y Minas, el Instituto Geológico Minero y Metalúrgico – INGEMMET en directa coordinación con la Dirección Regional de Energía y Minas de la región Puno – DREMP. Por el Estado Plurinacional de Bolivia, se ha conformado la comisión interinstitucional integrada por la Cancillería del Estado, Ministerio de Defensa, Ministerio de Minería y Metalurgia, Superintendencia de Minas, COMIBOL y SERGEOTECMIN, para realizar una inspección técnica al área de Suches en junio de 2009 y actualizada en septiembre de 2010. El objetivo de ambas comisiones, fue establecer la situación legal y la cantidad de las operaciones mineras existentes en la cuenca binacional del río Suches. Las comisiones de ambos países realizaron inventarios de las operaciones mineras, la situación legal de los derechos mineros (Perú) y peticiones y cuadrículas (Bolivia) y en la medida de lo posible realizar controles medio ambientales de acuerdo a la normatividad vigente en ambos países

Soil erosion control, plant diversity, and arthropod communities under heterogeneous cover crops in an olive orchard

A 3-year experiment compared in an olive orchard the effect of different cover crops’ composition on runoff, water erosion, diversity of annual plants, and arthropod communities which could provide an alternative to conventional management based on tillage (CT). The cover crops evaluated were a seeded homogeneous grass (GC), a seeded mix of ten different species (MC), and a non-seeded cover by vegetation naturally present at the farm after 20 years of mowing (MC). The results suggest that heterogeneous cover crops can provide a viable alternative to homogeneous ones in olives, providing similar benefits in reducing runoff and soil losses compared to management based on bare soil. The reduction in soil loss was particularly large: 46.7 in CT to 6.5 and 7.9 t ha year in GC and MC, respectively. The heterogeneous cover crops resulted in greater diversity of plant species and a modification of the arthropod communities with an increased number of predators for pests. The reduction of the cost of implanting heterogeneous cover crops, improvement of the seeding techniques, and selection of species included in the mixes require additional research to promote the use of this practice which can deliver enhanced environmental benefits.This study has been possible thanks to the support of Syngenta from 2002 to 2013, through projects ProTerra I, II and Biosuelo. Since 2009, some additional measurements and analysis have been possible to support by the projects P08-AGR-03643, P12-AGR-931, AGL2015-65036-C3-1, RESEL (Spanish Ministry for Environment and Rural and Marine Affairs), and FEDER funds. We also want to acknowledge the contribution of three anonymous reviewers who had helped greatly to improve the quality of the original manuscript.Peer Reviewe

Driving factors of forest growth: a reply to Ferry et al. (2012).

1. In a recent paper, we analysed the effects of climate, soil and logging disturbance on tree and forest growth (Toledo et al. 2011a). We took advantage of one of the largest data sets in the Neotropics, consisting of 165 1-ha plots and over 62 000 trees distributed over an area of c. 160 000 km2, across large environmental gradients in lowland Bolivia. The main findings were that climate was the strongest driver of spatial variation in tree growth, whereas soils had only a modest effect on growth and that the effect of logging disappeared after a few years. 2. Ferry (2012) suggest that we underestimated the disturbance effects on growth because of a supposedly wrong coding of Time After Logging (TAL) for unlogged plots. Although we have good biological reasons why we coded TAL like we did, we checked Ferry et al.s suggestions for recoding and found no differences in variables that significantly explained tree and forest growth. We agree, however, that for future research, it is important to go beyond simple descriptors such as time after logging and basal area logged, to better describe the variation in logging impact found in areas under forest management. 3. Ferry et al. claim that we did not define basal area growth properly. We believe this is a semantic issue, as we clearly defined basal area growth as the net change in basal area. This net basal area change in Bolivian forests is indeed relatively high compared to other studies, which may be attributed to the higher soil fertility and biogeographic differences in species composition and their traits. 4. Synthesis. Many apparent discrepancies in the ecological literature arise because tropical forest ecologists tend to see the world from the perspective of their own forest (despite clear biogeographic differences) and try to capture the same ecological processes using different variables and measurement protocols. To advance our understanding and go beyond single-case studies, we need to assemble large databases, quantify forest dynamics and disturbances in similar ways, be aware of differences among forests and analyse environmental doseresponse curves

Climate is a stronger driver of tree and forest growth rates than soil and disturbance

1. Essential resources such as water, nutrients and light vary over space and time and plant growth rates are expected to vary accordingly. We examined the effects of climate, soil and logging disturbances on diameter growth rates at the tree and stand level, using 165 1-ha permanent sample plots distributed across Bolivian tropical lowland forests. 2. We predicted that growth rates would be higher in humid than in dry forests, higher in nutrient-rich than nutrient-poor forests and higher in logged than non-logged forests. 3. Across the 165 plots we found positive basal area increases at the stand level, which agree with the generally reported biomass increases in tropical forests. 4. Multiple regression analysis demonstrated that climate variables, in particular water availability, were the strongest drivers of tree growth. More rainfall, a shorter and less intense dry period and higher temperatures led to higher tree growth rates. 5. Tree growth increased modestly with soil fertility and basal area growth was greatest at intermediate soil fertility. Surprisingly, tree growth showed little or no relationship with total soil nitrogen or plant available soil phosphorus. 6. Growth rates increased in logged plots just after logging, but this effect disappeared after 6 years. 7. Synthesis. Climate is the strongest driver of spatial variation in tree growth, and climate change may therefore have large consequences for forest productivity and carbon sequestration. The negative impact of decreased rainfall and increased rainfall seasonality on tree growth might be partly offset by the positive impact of increased temperature in these forests

Climate is a stronger driver of tree and forest growth rates than soil and disturbance

1. Essential resources such as water, nutrients and light vary over space and time and plant growth rates are expected to vary accordingly. We examined the effects of climate, soil and logging disturbances on diameter growth rates at the tree and stand level, using 165 1-ha permanent sample plots distributed across Bolivian tropical lowland forests. 2. We predicted that growth rates would be higher in humid than in dry forests, higher in nutrient-rich than nutrient-poor forests and higher in logged than non-logged forests. 3. Across the 165 plots we found positive basal area increases at the stand level, which agree with the generally reported biomass increases in tropical forests. 4. Multiple regression analysis demonstrated that climate variables, in particular water availability, were the strongest drivers of tree growth. More rainfall, a shorter and less intense dry period and higher temperatures led to higher tree growth rates. 5. Tree growth increased modestly with soil fertility and basal area growth was greatest at intermediate soil fertility. Surprisingly, tree growth showed little or no relationship with total soil nitrogen or plant available soil phosphorus. 6. Growth rates increased in logged plots just after logging, but this effect disappeared after 6 years. 7. Synthesis. Climate is the strongest driver of spatial variation in tree growth, and climate change may therefore have large consequences for forest productivity and carbon sequestration. The negative impact of decreased rainfall and increased rainfall seasonality on tree growth might be partly offset by the positive impact of increased temperature in these forests