Effects of management practices on water yield in small headwater catchments at Cordillera de los Andes in southern Chile

In several parts of the world, drinking water is obtained from springs in natural and managed mountainous forests. Since forests regulate quality as well as quantity of water, the effects of forest-management activities on water yield are an important subject of study. The objective of this study was to evaluate the effects of forest management on water yield in managed and unmanaged temperate native rainforests in the Andean range of southern Chile. The study area is located in San Pablo, a forest reserve of 2,184 ha located at the Andean range of southern Chile (39º 35’ S, 72º 07’ W, 600-925 m a.s.l.). From April 2003 to October 2008, seven experimental small catchments were monitored for rainfall, throughfall, stemflow, soil water infiltration, soil water percolation and runoff. In 2002, one catchment with a secondary deciduous forest was managed, through thinning, causing a reduction in basal area by 35% whereas the other one remained unthinned as control. Both watersheds are adjacent and are located at 600 – 720 m of elevation on deep loam textured volcanic soils (100 - 120 cm). In November 2006, a watershed covered with evergreen old-growth forests was thinned extracting 40% of the total basal area whereas another adjacent catchment remained unthinned as control. Both watersheds are located at 725 – 910 m a.s.l. and have the same aspects. The effects of management of deciduous secondary forests showed that for the period April 2003-March 2007, the mean value of the increase in total annual streamflow was 12.7%, ranging from 10.9% to 14.6%. Thinning of the evergreen old-growth forest increased the streamflow for the period November 2006-October 2008 with 6.1%, ranging from 4.4% to 7.8%, with greater differences during summertime (15.7 to 206%)

An approach to the functioning of mountain streams in Northern Andean Patagonia

Los Andes patagónicos tienen como vegetación característica los bosques de Nothofagus, que seextienden desde los 37° a los 55° S. En particular, N. pumilio (lenga) es la especie más ampliamente distribuida tanto en la Argentina como en Chile, y por ser decidua representa un notable pulso estacional de materia orgánica a los arroyos de cabecera. Estos arroyos tienen su origen en las alturas de las montañas y drenan las laderas hacia aguas bajas. Hace más de una década que se realizan estudios en la cuenca del Challhuaco, ubicada en la zona norte y en el extremo este de los Andes patagónicos. Los estudios abarcaron tanto aspectos estructurales como funcionales de la ecología de arroyos e incluyen el análisis de nutrientes y materia orgánica a lo largo de la cuenca, y relaciones alimentarias entre los diferentes componentes de sus tramas tróficas, desde productores primarios, descomponedores de detrito vegetal e invertebrados bentónicos hasta consumidores superiores como la trucha arcoíris. El objetivo de esta revisión fue integrar los resultados obtenidos sobre el funcionamiento de los sistemas fluviales de cabecera andino-patagónicos y su respuesta a factores de cambio espaciales (a lo largo de una cuenca) y temporales (entre estaciones). Finalmente, se destacan los conflictos y las amenazas más importantes que enfrentan estos sistemas (modificaciones en la cobertura vegetal, introducción deganado, cambio climático) para señalar los aspectos que se deberían incorporar a las políticas de conservación, incluyendo un manejo sustentable de las actividades forestales y la cría de ganado.Patagonian Andes has Nothofagus forests as characteristic vegetation, which extends from 37° to 55° S. In particular, N. pumilio (lenga) is the most widely distributed species, both in Argentina and Chile, and as it is a deciduous species, it represent an important organic matter input to headwater streams. These streams are originated in high altitude mountains and drain the forest downstream. We have been studying the ecology of Challhuaco catchment, in the Northeast of Patagonian Andes, for more than a decade. These studies encompassed both structural and functional aspects of stream ecology, including nutrient and organic matter analysis along the catchment, and feeding relation between the different components of food webs, from primary producers, leaf litter decomposers and benthic macroinvertebrates to top consumers, as the rainbow trout. In this review we aimed to gather and relate results of a catchment that may be used as a model to extrapolate to other Andean Patagonian catchments. Finally, we indicated some conflicts and threats to which these systems are exposed, to point out the aspects that should be incorporated into conservation policies including a more sustainable management of forestry and cattle raising.Fil: Diaz Villanueva, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Limnología; ArgentinaFil: Albariño, Ricardo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Fotobiología; Argentin

Aboveground nutrient cycling in temperate forest ecosystems of southern Chile

Forest ecosystems have important ecological, economic, and social values, but are subject to varying ecosystem pressures, including enhanced atmospheric nitrogen deposition. This paper quantifies nutrient fluxes in varying forest types in southern Chile in order to evaluate external and internal nutrient cycling within ecosystems, with a focus on the aboveground compartment. The objectives were to establish baseline data for pristine forest ecosystems and to study differences between forest types. Measurements were performed in four stands in the lower Andean mountain range (San Pablo de Tregua), two stands in the Central Depression (Paillaco) and six catchments in the Coastal mountain range (40°S). External nutrient inputs and losses were assessed by analyzing precipitation, throughfall, stemflow, soil percolation, and streamflow. Internal aboveground nutrient cycling was quantified by means of a canopy budget model, litterfall collection, and a litterbag decomposition experiment. Although temperate forests in southern Chile still represent a unique opportunity to study pristine ecosystems, measurements of water and ion fluxes indicate that forests in the central depression are exposed to enhanced external nitrogen inputs

Forest hydrology in Chile: Past, present, and future

This paper reviews the current knowledge of hydrological processes in Chilean temperate forests which extend along western South America from latitude 29° S to 56 ° S. This geographic region includes a diverse range of natural and planted forests and a broad sweep of vegetation, edaphic, topographic, geologic, and climatic settings which create a unique natural laboratory. Many local communities, endangered freshwater ecosystems, and downstream economic activities in Chile rely on water flows from forested catchments. This review aims to (i) provide a comprehensive overview of Chilean forest hydrology, to (ii) review prior research in forest hydrology in Chile, and to (iii) identify knowledge gaps and provide a vision for future research on forest hydrology in Chile. We reviewed the relation between native forests, commercial plantations, and other land uses on water yield and water quality from the plot to the catchment scale. Much of the global understanding of forests and their relationship with the water cycle is in line with the findings of the studies reviewed here. Streamflow from forested catchments increases after timber harvesting, native forests appear to use less water than plantations, and streams draining native forest yield less sediment than streams draining plantations or grassland/shrublands. We identified 20 key knowledge gaps such as forest groundwater systems, soil–plant-atmosphere interactions, native forest hydrology, and the effect of forest management and restoration on hydrology. Also, we found a paucity of research in the northern geographic areas and forest types (35-36 ° S); most forest hydrology studies in Chile (56 %) have been conducted in the southern area (Los Rios Region around 39-40 ° S). There is limited knowledge of the geology and soils in many forested areas and how surface and groundwater are affected by changes in land cover. There is an opportunity to advance our understanding using process-based investigations linking field studies and modeling. Through the establishment of a forest hydrology science “society” to coordinate efforts, regional and national-scale land use planning might be supported. Our review ends with a vision to advance a cross-scale collaborative effort to use new nation-wide catchment-scale networks Long-term Ecosystem Research (LTER) sites, to promote common and complementary techniques in these studies, and to conduct transdisciplinary research to advance sound and integrated planning of forest lands in Chile

The impacts of biotic and abiotic factors on resource subsidy processes - leaf litter breakdown in freshwaters

Freshwaters are closely linked with adjacent terrestrial ecosystems through reciprocal resource subsidies, which are fluxes of nutrients, organisms, and materials between ecosystems. Terrestrial ecosystems provide many resource subsidies to freshwaters including leaf litter, one of the most prevalent terrestrial-derived subsidies. Inputs of leaf litter fuel detritivores food web, as food resources and refuges, and affect nutrients cycling in freshwaters. The decomposition of leaf litter is subjected to many biotic and abiotic factors, which makes it a good indicator of freshwater ecosystem functioning. Yet, this ecosystem process has been affected by anthropogenic disturbances that alter abiotic and biotic factors in the nature. Therefore, this thesis aimed to investigate some previously under-investigated or unclear but important factors that may affect the decomposition of leaf litter in streams. First, I reviewed the importance of resource subsidy fluxes between riparian zones and freshwaters and how these subsidies can influence recipient ecosystems. Then, I conducted a field experiment exploring the effects of anthropogenic carrion subsidy (chicken meat) and environmental-relevant concentration of glyphosate (the most widely applied herbicides worldwide) on leaf litter decomposition and invertebrate communities colonizing in the leaf-litter bags deploying in streams with different types of land use. Next, I conducted a mesocosm experiment nearby an urban stream to investigate the effects of water temperature (~ 8 oC above vs ambient), consumer - snails (presence vs absence), and leaf-litter quality (intact vs >40 % leaf area was consumed by terrestrial insects) on litter decomposition. Finally, I explored the global patterns of riparian leaf litter C, N, P, and their stoichiometric ratios to gradients of climatic (mean annual temperature and precipitation) and geographic (absolute latitude and altitude) factors, and the differences between biotic factors (phylogeny, leaf habit, N-fixing function, invasion status, and life form). The results of field experiment indicated that: in coarse mesh bags, glyphosate, carrion subsidy, and the addition of both decreased litter breakdown rates by 6.3 %, 22.6 %, and 24.3 % respectively; in fine mesh bags, glyphosate and the addition of both retarded litter breakdown rates by 8.3 % and 12.5 % respectively. Litter decomposition also differed among streams, with the highest breakdown rates in village streams and lowest in urban/suburban streams. Invertebrates were significantly different among streams, with biodiversity index and total taxon richness were highest in village streams and lowest in suburban stream. However, overall effects of carrion subsidy and glyphosate on macroinvertebrates were not significant. The results of mesocosm experiment indicated that warming and the presence of snails accelerated litter decomposition by 60.2 % and 34.9 % respectively, while litter breakdown rates of terrestrial insect damaged leaves were 5.1 % slower than intact leaves because of lower leaf litter quality. The results of meta-analysis study demonstrated that global riparian leaf litter had higher N and P, while lower C, C:N, and C:P ratios than terrestrial leaf litter in general. Riparian leaf litter quality changed with gradients of climatic and geographic predictors, and these patterns differed between leaf habits (evergreen or deciduous) and climate zones (tropical or non-tropical area). In general, my research provides important information on resource subsidy processes, which will benefit freshwater ecosystem management to support biodiversity and maintain ecosystem services

Effects of land cover change on mountain streams : a multi-level approach

Los cambios en la ocupación del suelo, en combinación con el cambio climático, son los impactos humanos más influyentes en los ecosistemas fluviales. Esta tesis analiza los efectos que los cambios en la ocupación del suelo tienen sobre las vías de flujo de energía, la composición y estructura de las redes tróficas y la multifuncionalidad del ecosistema (incluyendo la producción primaria y respiración del ecosistema, la descomposición de la materia orgánica y el crecimiento del biofilm) en ríos de montaña, a través de componentes fluviales físicos y químicos (p. ej. disponibilidad de luz, nutrientes, temperatura) y la alteración de los recursos tróficos basales (p. ej. hojarasca, algas, materia orgánica disuelta). Los resultados de este enfoque multinivel serán altamente valiosos para diseñar soluciones que permitan mitigar los efectos de los cambios en la ocupación del suelo y conservar el funcionamiento de los ríos de cabecera y los servicios que éstos proporcionan.Land use-land cover changes, in concert with climate change, are the most extensive and influential human impacts on fluvial ecosystems. This thesis addresses the effects of land cover change, on mountain stream energy flow pathways, food web size structure and composition and ecosystem multifunctionality (including primary production and ecosystem respiration, organic matter decomposition and biofilm growth) through the alteration of the basal food resources that constitute the sustenance of stream food webs (e.g. leaf litter, algae, dissolved organic matter) and physical and chemical fluvial components (e.g. light availability, nutrients, temperature). The results obtained from this multi-level approach will be highly valuable to design management solutions for mitigating the effects of land cover change and conserve headwater stream ecosystem functioning and service provision.Proyecto RIVERLANDS: Efectos del legado del uso del suelo en los procesos fluviales: implicaciones para la gestión integrada de cuenca del Ministerio de Economía y Competitividad (Ref: BIA2012-33572

Comunidades de Trichoptera en ríos patagónicos sometidos a diferentes usos de la tierra

Tesis presentada para optar al Grado de Doctor en Ciencias NaturalesFil: Brand, Cecilia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentin

Assessment of large wood budget in two different rivers located in Alpine and Andean environment

In forested river basins, Large Wood (LW) is a key component responsible for the geomorphological and ecological aspect of fluvial systems but, at the same time, is a source of hazard for sensitive places. Given its dual role, the analysis and quantification of LW in rivers, as well as understanding its mobilization and deposition, are crucial steps in order to ensure an appropriate management of riverine areas. This study attempts to increase knowledge in the main LW-related processes, such as the lateral recruitment from bank erosion, fluvial transport and the presence of buried LW, assessing the LW budget in two rivers. The study was conducted in two different fluvial environments. A 3.7 km-long reach was selected along the middle course of the Italian Piave River, a human impacted gravel-bed river typified by wandering and island-braided morphologies. In addition, three 80 m-long reaches were selected along the lower course of the Chilean Blanco River, a natural river with a morphology that drastically changed because of a recent volcanic eruption. The three considered items of the budget were analyzed by field activities conducted during the three years of the PhD. The lateral recruitment of LW was analyzed only in the Piave River for an over-bankfull flood (RI~7yr) by measuring, positioning and tagging all standing trees (D≥ 0.1m) within a 20 m buffer wide along the floodplain banks and island perimeters. A similar methodology was used to investigate, in both rivers, the fluvial transport of LW by considering all woody elements (D≥0.1m and L≥1m) within the active channel. In this way, during post-event surveys it was possible to identify the input (deposition) and output (mobilization) elements. Because the sediments from the volcanic eruption caused the burial of several standing trees and LW, the presence of buried LW was explored only in the Blanco River by Ground Penetrating Radar (GPR) testing. In the Piave River, the LW budget was assessed for very low floods (RI<1yr), whereas in the Blanco River ordinary (RI~1yr) and not-ordinary floods (RI 10-25yr) were considered. The results highlighted that, in the Piave River, the recruitment from bank erosion is a common process for the supply of LW. Volumes of recruited LW were found to vary according to the extension of the eroded surface, type of eroded morphological unit and riparian vegetation characteristics. Larger volumes (25.1 m3∙km-1) are recruited from both the floodplain and fluvial islands during not-ordinary floods (RI~7yr), whereas for ordinary events (RI<1yr) small amounts of LW (0.21 m3∙km-1) are recruited just from the floodplain. Furthermore, flood magnitude was found to be an important factor controlling the temporal fluctuations of LW storage, resulting in decreases and increases of LW abundance during ordinary and not-ordinary events, respectively. The increase in wetted area results in a greater inundation of fluvial bars that allows, at the same time, the mobilization and deposition of LW. In addition to the role of flood magnitude, the local-scale morphology of the river appeared to be another factor influencing the changes in LW abundance, with greater variations in multi-thread than single-thread channels, where the larger and faster increase in the inundated area increases the amount of in-transport LW. In particular, the budget for the Piave River featured negligible variations in LW storage (-9.7%) and a very low mobility rate (1.43%) reflecting the low magnitude of occurred events. By contrast, a higher dynamicity of LW was found in the Blanco River also during ordinary events, with mobility rates ranging from 41 to 94% and LW storage increasing up to 179%, because of the considerable input volumes (highest input of 285.35 m3∙ha-1). The complexity of LW dynamics in the Blanco River is also due to the presence of buried LW (1.65 m3∙ha-1) that can be easily exhumed and, thus, increase the amount of in-transport LW. This volume was obtained as a first approach with the GPR that proved to be a valid and non-destructive method to bridge this gap. The results obtained in this study can be considered useful advances in understanding the three main LW-related processes (recruitment, mobilization, deposition), knowledge of which is essential in order to ensure the positive contributions of wood to river ecosystems, and minimize potential hazards adopting correct management plans

Biological invasions in brackish waters

Invasive non-native species (NNS) cause deleterious ecological, economic, social impacts worldwide. Brackish waters are transitional areas subject to invasion by taxa that may subsequently spread into adjacent freshwater and marine systems. The tendency for ports to be situated in brackish estuaries makes them particularly susceptible to ship-borne introductions of NNS. Despite being reported as heavily invaded ecosystems with a disproportionately high abundance of NNS, studies on biological invasion in brackish waters has received considerably less attention than truly freshwater and marine systems. In this thesis, I investigate the discovery, ecological impacts, and management of NNS in brackish waters. I begin by conducting a systematic review and meta-analysis comparing the ecological impacts of NNS in brackish, freshwater, and marine environments around the globe. I reveal that NNS have led to an overall decrease in the abundance and diversity of the resident communities in freshwater and marine environments, but not in brackish waters. NNS in brackish estuaries provide novel habitats, which can facilitate the establishment of other NNS, leading to an invasional meltdown. Next, I explore the first records of all freshwater, brackish and marine NNS in Great Britain and show that many NNS were first discovered in estuaries and often aggregated around the major shipping ports. This result provides support that many marine and freshwater NNS in Great Britain could have been introduced via international ships visiting brackish waters. I then focus on one NNS, the Gulf wedge clam, Rangia cuneata, which is a brackish water bivalve currently invading European waterways. I show that the growth and feeding rates of R. cuneata differed at the two extremes of salinity tolerated by this species, and consider how this intraspecific variation might drive context-specific ecological impacts. I go on to demonstrate the potential detrimental impacts of R. cuneata as a result of their much higher feeding rates and greater functional responses compared to a sympatric, native unionid mussels. I finish by investigating two methods to control invasive species in brackish waters. I show that using saline, but not freshwater, shock could effectively control R. cuneata. I then demonstrate the effectiveness of two new formulations of microencapsulated biocides in controlling R. cuneata. Taken together, these studies provide important insights into the discovery, impacts and management of NNS in brackish waters. My findings demonstrate the need for greater monitoring for NNS in brackish systems, and especially those subject to high ship traffic. The control methods proposed here have wide application in many brackish systems and for many species, thus providing much needed effective tools for the rapid response to the discovery of high risk invasive NNS in this important but overlooked transitional habitat.This study is funded by a Gulbenkian Yuval Cambridge Studentship at Churchill College and a Graduate Scholarship from Natural Sciences and Engineering Research Council of Canada