Claudia Rojas ● Profesora Asociada

Sistema Articulado de Investigación en Cambio Climático y Sustentabilidad de Zonas Costeras de Chile CUECH/RISUE RED21992

Sistema Articulado de Investigación en Cambio Climático y Sustentabilidad de Zonas Costeras de Chile CUECH/RISUE RED21992

Mining activities have discharged large amounts of wastes or mine tailings to the environment, which represent an important environmental issue. Mine tailings are mainly characterised by poor physicochemical properties that limit the plant establishment and development. The most negative property in these mine wastes is the high content of metals and metalloids [metal(loid)s], which are often highly toxic due to acid pH that increases metal(loid) bioavailability. This negatively affects living organisms and ecological functioning since soil microorganisms are pioneer colonisers that mediate the plant establishment. Also, mine tailings are usually deposited in abandoned locations of large land cover; from where, due to their physical characteristics, they can be transported by air and water, affecting communities and the environment in surrounding areas. There are several industrial strategies focused on the physical and chemical management of mine tailings, but these are highly expensive and occasionally not effective. These strategies have not been suitable techniques to reduce negative impacts of mine tailings on the environment. In this context, biological approaches, such as phytoremediation, have been proposed as more appropriate strategies due to low cost, easy applicability, and promising results. Nevertheless, most of the studies focused on phytoremediation of mine tailings, especially Chilean studies, have been performed in laboratory conditions. Although these studies show promising conclusions, in many cases unsuccessful results are obtained at field conditions, mainly due to laboratory experiments do not consider the dynamic field variability and potential ecological interactions. Based on the above, the proposed research aims to evaluate the effect of the initial addition of organic-mineral amendments and the bioaugmentation of microbial communities with “core microbiome” from the root-zone of native herbaceous on the growth and development of native plants and microbial communities at copper mine tailings. We hypothesise that the growth and development of native plants in mine tailings will be promoted by the improvement of physicochemical properties of modified mine tailings (incipient technosols) through the addition of organic-mineral amendments, and the bioaugmentation of microbial communities with “core microbiome” involved in plant fitness obtained from copper mine tailings and surrounding soils. To evaluate the mentioned hypothesis, this study will be executed in three phases: 1) Initial field characterisation: this will be done for mine tailings and soils under sclerophyllous forest; 2) Collection and recruitment of “core microbiome”: this will study the composition, function, and interactions of “core microbiome” obtained from the root-zone of native herbaceous established on mine tailings and soils under sclerophyllous forest, by which a laboratory-scale assay it is needed to produce inoculum of such ecological units (cores); 3) Restoration field experiment: this consists on the field establishment of native herbaceous species by bioaugmentation with “core microbiome” from root-zone mine tailings and root-zone soil on incipient technosols produced by the addition of organic-mineral amendments on mine tailings. These phases are designed to be performed in three years. This study can provide insights of the promotion of ecological process and natural resilience on microbial communities of mine tailings and surroundings, which can allow the initial plant establishment a development for later possible plant recruitment from the native sclerophyllous forest. This would also evaluate whether mine tailings can be in situ managed instead of been totally removed, which implies high costs and workflow to enterprises. Additionally, this study would represent the first approach of the evaluation of the biological functioning and composition of microbial communities from root-zone mine tailings in Chile, from its current state to the subsequent restoration process.

Fires have historically played an important role in the composition and distribution of terrestrial ecosystems. However, these events have also represented an important pressure that have induced land degradation worldwide; especially in regions with Mediterranean climates with dry summers and elevated temperatures. In forests, fires not only exert an individual effect on each of their components; including vegetation, animals and other natural resources such as soil and water, among others, but also on the relationship among these constituents, which in turns, compromise the functionally of the whole ecosystem. Forest fires directly affect aboveground biomass production and other ecosystem services (i.e. benefits society directly or indirectly obtain from ecosystems). Land burning can also compromise belowground conditions that are essential to support aboveground life. Though soil biological processes are recognized as main drivers of ecosystem recovery following fires, the consequences of land burning on soil microorganisms are less understood than those on soil physicochemical properties. The present research aims precisely to elucidate what are the effects of fires on a particular group of soil microorganisms, crucial for maintenance of proper soil ecosystem services and natural resilience. The microbial specialist studied in this project would be microorganisms capable of nitrogen fixation (diazotrophs), particularly those living in non-mutualistic associations in soil environments (within the soil rhizosphere or as free-living organisms in bulk soils). It is known that land burning can negatively impact soil microorganisms directly by compromising diversity and altering their composition; moreover, these pressures can also indirectly affect soil microbiota by altering soil physicochemical properties. Recently, advanced on molecular biology and analytical techniques have allowed to incorporate the study of microbial interactions and adaptations following soil disturbances. Microbial co-occurrences network studies have shed lights on particular microbial taxa relationships (negative and positive) and adaptations to changes in soil abiotic factors following disturbances. Thus, these analyses can contribute to better understand the ecological significance of environmental pressures on proper soil ecosystem functioning considering the previous background, the present study aims to assess through ecological molecular analyses how non-mutualistic diazotrophic microorganisms interact with other members of the bacterial community and adapt to changes in soil physicochemical conditions in Mediterranean forest following fires. In the present work, it is hypothesized that ecological networks will reveal shifts in non-mutualistic diazotrophic population structure in Mediterranean forest after fires, due to changes in their interactions with other microorganisms and responses to modified physicochemical properties. To test this hypothesis, classical soil physicochemical analyses and cutting-edge, molecular based, microbial ecology analyses will be implemented in burned and unburned soils of two Mediterranean native forest in the Region of O’Higgins in central Chile. The strategy used for this study will consist of two types of studies: 1) at the field scale, and 2) at a field-laboratory scale. The field scale study will include burned areas and unburned areas for comparison. The field-laboratory scale experiment will consist of soil samples taken in the field, burned in the laboratory, and incubated at their original site for different periods of time. By accomplishing the proposed project, it is expected to identify what are the main biotic conditions (e.g. taxa positively or negatively interacting with diazotrophs) and the main abiotic parameters correlating with these interactions in burned and unburned soils. This knowledge would allow to better design and implement soil restoration initiatives in Mediterranean native forest, which will in turn contribute to the reestablishment of proper functionally of the whole forest ecosystem, contributing to sustain their ecosystem services and their natural resilience towards future environmental pressures.

Objetivo general Evaluar el efecto de técnicas silviculturales sobre el establecimiento de especies del bosque esclerófilo (Kageneckia oblonga, Lithraea caustica, Quillaja saponaria y Schinus polygamus) en sitios degradados y de baja disponibilidad hídrica. Objetivos específicos Como hipótesis de investigación se plantea que (1) En la fase de establecimiento, plantas producidas en contenedores más largos y con poda lateral debieran presentar mayor volumen radicular y con ello mayor sobrevivencia en campo. Casillas con componentes retenedores de humedad tales como materia orgánica e hidrogel debieran presentar mayor contenido de humedad de suelo en el periodo estival y así mayor sobrevivencia de planta. (2) La aplicación de riego debiera generar mayor sobrevivencia solamente en plantas provenientes de contenedores más pequeños plantadas en casillas sin aplicación de componentes que retengan humedad. La metodología contempla la selección de un conjunto de especies endémicas pertenecientes al tipo forestal esclerófilo de interés para la restauración del bosque esclerófilo. En una primera fase en vivero, se analizarán los atributos de calidad de planta y los cambios morfológicos del sistema radical, generados a partir del cultivo en diferentes tipos de contenedor (tamaño 15x15 cm y 13x20cm) en todas las especies durante una temporada de crecimiento. La segunda fase de campo, contemplará una plantación experimental que se localizará en una zona rural de la Región Metropolitana cuyas características son representativas de ambientes con severas limitaciones abióticas para el establecimiento de plantaciones. Se establecerán parcelas de 3200 m2 para cada especie por separado. El estudio será un diseño factorial en bloques completos al azar con 16 tratamientos (n=50). Los tratamientos consisten en una combinación de 2 niveles de tamaño de contenedor (plantas provenientes de vivero), 4 niveles de casilla de plantación y 2 niveles de frecuencia de riego. En total se establecerán 3200 plantas de las 4 especies. Específicamente, se probará el uso de casillas de plantación profundas (40x80 cm), las cuales variarán en el tipo de combinación de materiales de relleno (control con suelo; mezcla suelo y rocas 3:1; mezcla suelo y materia orgánica 3:1; mezcla suelo e hidrogel 3:1). Adicionalmente, se aplicarán dos frecuencias de riego (riego de subsistencia cada 30 días y riego normal cada 7) en primavera y verano por dos temporadas de crecimiento. Se medirán los cambios en la humedad de suelo y la tasa de colonización de raíces en la casilla de plantación. Durante la estación seca estival (octubre a abril) se medirán la tasa de sobrevivencia y crecimiento de todas las especies, así como el estado hídrico de las plantas sometidas a diferentes frecuencias de riego. Resultados De los resultados de esta investigación se espera generar importante información acerca de alternativas de manejo de plantas en contenedor, así como validar la importancia del manejo de la casilla de plantación mediante el uso de una combinación de materiales que favorecen la capacidad de retención de agua y la infiltración en el suelo para promover el crecimiento de raíces en profundidad. Esta información es relevante en el área de la restauración ecológica, específicamente para la identificación de criterios de calidad de planta en vivero, selección de especies para ambientes semiáridos, diseño y planificación de plantaciones con énfasis en técnicas de conservación de la humedad en la casilla de plantación a largo plazo y con mínimo aporte de riego y la valorización de las prácticas potencialmente bonificables por la ley 20.283, que favorezcan la sobrevivencia de las especies en estudio.

Objetivo General: Evaluar la presencia de pesticidas en tejidos vegetales y su potencial transferencia por ingesta de alimentos a jóvenes que habitan en la región de O'Higgins